S. cerevisiae

Mol Gen Genet, 1981, 182(2), 196 - 205
Repair of interstrand cross-links in DNA of Saccharomyces cerevisiae requires two systems for DNA repair: the RAD3 system and the RAD51 system; Jachymczyk WJ et al.; We have studied the role of the excision-repair system and the recombination-repair system in the removal of cross-links and monoadducts caused by furocoumarins plus 360 nm radiation in yeast DNA by neutral and alkaline sucrose gradients and by a fluorometric procedure which detects cross-linked DNA molecules . We found that the excision-repair system, represented by the rad3 mutations, is required both for the removal of monoadducts, causing single-strand break formation, and for the removal of cross-links, causing double-strand break formation . The recombination-repair system, represented by the rad51 mutation, is necessary for double-strand break repair following cross-link removal, but it has no role in the repair of monoadducts . It can be concluded, that at least some of the same enzymes are used in yeast for both the excision of pyrimidine dimers and the excision of cross-links or monoadducts caused by furocoumarins plus light . The RAD3 and RAD51 repair systems, which act independently in the repair of UV-induced lesions, are part of a single system for the repair of cross-links.

Antonie Van Leeuwenhoek, 1981, 47(3), 193 - 207
Extracellular protein release and its response to pH level in Saccharomyces cerevisiae; Weller J et al.; Saccharomyces cerevisiae grown in batch culture at pH 5.5 releases 0.1 to 0.2 pg protein per cell to the external medium over a period of four to five days, final concentration 20-40 micrograms/ml . Cells grown at pH 3.0 release 10-fold this quantity (1-2 pg/cell, final concentration 100-200 micrograms/ml) . A kinetic model based on published behavior of periplasmic protein gave a good fit to the observed kinetics of exoprotein yield . The electrophoretic pattern of exoprotein differed from that of cell lysate protein, and exoprotein synthesis was apparently limited to early stages of the life cycle . These results are consistent with the identification of exoprotein as periplasmic protein released to the external medium through the cell wall . Analysis of the observed kinetics of exoprotein yield, utilizing the kinetic model suggests that the greater exoprotein production of cells grown at pH 3.0 was due entirely to greater synthesis of periplasmic proteins while the fraction of periplasmic protein released per unit time was greater for cells grown at pH 5.5 . The latter conclusion is supported by thicker cell walls of cells grown at pH 3.0 as observed by electron microscopy . At an applied level the apparent limitation of exoprotein synthesis to the first few hours of cell life, the slow leakage of exoprotein through the cell wall, and the dilute nature of a yeast suspension do not favor the utilization of yeast cells for direct conversion of substrate into protein released to the external medium.

Mol Gen Genet, 1981, 182(1), 1 - 6
Sporulation of products of protoplast fusion without regeneration in Saccharomyces cerevisiae; Tsuboi M; In Saccharomyces cerevisiae, diploid strains which are respiratory deficient (e.g., rho-) or are homozygous for the mating-type locus (i.e., either a/a or alpha/alpha) are unable to sporulate . In order to induce sporulation in these nonsporulating strains, the technique of protoplast fusion mediated by polyethylene glycol was adopted . In this study, the products of protoplast fusion were induced to sporulate without reversion to normal cells . Protoplasts from a respiratory-deficient diploid strain were mixed with those from a respiratory-competent haploid one carrying mitochondrial drug resistance markers, treated with 30% polyethylene glycol-4000 and 25 mM CaCl2, and incubated in 0.1 M potassium acetate containing 0.8 M sorbitol as an osmotic stabilizer . After two days' incubation, asci with three to eight spores were formed at a frequency of 1 x 10(-3) to 2 x 10(-4) . Sporulation was also observed in products of fusion between an a/a diploid and alpha haploid strains and between an alpha/alpha diploid and a haploid strains . The analysis of the genotypes of spores revealed that when fusion products were cultured under conditions for sporulation, karyogamy did not take place, diploid nuclei underwent meiosis, and both diploid and haploid nuclei were able to develop into spores.

Genetics, 1981 Jan, 97(1), 45 - 64
Protein degradation, meiosis and sporulation in proteinase-deficient mutants of Saccharomyces cerevisiae; Zubenko GS et al.; During the process of sporulation, a/alpha diploids degrade about 50% of their vegetative proteins . This degradation is not sporulation specific, for asporogenous diploids of a/a mating type degrade their vegetative proteins in a fashion similar to that of their a/alpha counterparts . Diploids lacking carboxypeptidase Y activity, prc1/prc1, show about 80% of wild-type levels of protein degradation, but are unimpaired in the production of normal asci . Diploids lacking proteinase B activity, prb1/prb1, show about 50% of wild-type levels of protein degradation . The effect on degradation of the proteinase B deficiency is epistatic to the degradation deficit attributable to the carboxypeptidase Y deficiency . The prb1 homozygotes undergo meiosis and produce spores, but the asci and, possibly, the spores are abnormal . Diploids homozygous for the pleiotropic pep4-3 mutation show only 30% of the wild-type levels of degradation when exposed to a sporulation regimen, and do not undergo meiosis or sporulation . Neither proteinase B nor carboxypeptidase Y is necessary for germination of spores . Approximately half of the colonies arising from a/a or alpha/alpha diploids exposed to the sporulation regimen that express an initially heterozygous drug-resistance marker (can1) appear to arise from mating-type switches followed by meiosis and sporulation.

Antonie Van Leeuwenhoek, 1981, 47(2), 121 - 31
induction and derepression of arginase and ornithine transaminase in different strains of Saccharomyces cerevisiae; Middelhoven WJ et al.; The syntheses of arginase and ornithine transaminase were studied in two strains of Saccharomyces cerevisiae, viz . strain B and strain alpha-sigma 1278b . Derepression of both enzymes during nitrogen starvation was shown only by strain B, non-specific induction of arginase only by strain alpha-sigma 1278b . This different response of both strains studied reveals substantial differences in the regulation of enzyme synthesis among yeast strains of one and the same species . The specific enzyme activities observed in chemostat cultures with arginine as the nitrogen source and different sugars, at variable carbon to nitrogen ratios, did not indicate the involvement of carbon catabolite repression in the regulation of arginase and ornithine transaminase syntheses . Specific arginase activities observed in the continuous cultures varied widely and did not show a correlation with the intracellular arginine concentration . Extracellular steady-state arginine concentrations higher than about 1.0 mM, in addition to abundant energy supply, were found to be required for high production of arginase . It is suggested that, besides intracellular arginine, extracellular arginine may provide an induction signal necessary for full-scale induction of arginase synthesis . A possible intermediary role of arginine permeases or of other membrane proteins is discussed.

Genetika, 1981, 17(6), 1000 - 8
{Genetic effects of the breakdown of tritium incorporated into Saccharomyces cerevisiae yeast cells . IV . The lethal and mutagenic effects and the nature of the mutations induced by tritium breakdown in the 5th position of cytosine}; Ivanov EL et al.; We have studied in lethal and mutagenic effects and the nature of mutations induced by 3H decays in the 5-th position of cytosine (5-3H-C) . The lethal efficiency was determined as alpha 1 = (10.3 +/- 6.7) x 10(-3) decay-1 or alpha 1 = (12.9 +/- 9.4) x 10(-5) rad-1 and the mutagen efficiency for ade1, ade2 genes -- as alpha m = (4.3 +/- 2.3) x 10(-7) decay-1 or alpha m = (5.4 +/- 2.9) x 10(-9) rad-1 . For ade2 gene the spectrum of mutations induced by 5-3H-C was as follows: 1% of frameshifts and 99% of base pair substitutions -- 9% of transversions, 3% of AT leads to GC transitions and 87% of GC leads to AT transitions . Our results establish the 5-3H-C as one of the most effective and specific mutagens reported so far for yeast . According to the scheme of Krasin with coworkers, the final product of 3H decay in the 5-th position of cytosine is uracil . Our calculations show that more than 90% of uracil residues are removed from the yeast genome by cell repair systems.

Genetika, 1981, 17(5), 822 - 31
{Mechanism of mutant induction in the ade2 gene of diploid Saccharomyces cerevisiae yeasts by ultraviolet rays}; Gordenin DA et al.; Ultraviolet light (UV) at 3000 ergs/mm-2 induces ade2 mutants with a frequency about 10(-4) in wild-type haploid strains of yeast and about 10(-5) in diploid wild-type strains . UV irradiation effectively induced mitotic segregation of ade2 in the heterozygous diploid (the frequency of segregation is 6%) . Interallelic complementation and localization spectra are similar for mutations induced both in haploids and diploids . The occurrence of ade2 mutants in diploids correlated with mitotic segregation of the marker his8 which is situated in the same arm of XY chromosome as ade2 is, distal to the centromere . Our data about the frequency of ade2 mutants in diploids and haploids, the frequency of ade2 mitotic segregation, mitotic segregation of other markers and genetic characteristics of ade2 mutations confirm the suggestion that the major mechanism of diploid ade2 mutants appearance is mutation in one of the two ADE2 alleles and consequent mitotic homozygotisation of mutation as a result of mitotic crossingover between ade2 and the centromere.

Genetika, 1981, 17(3), 405 - 10
{Genetic effects of N-nitroso-N-methylurea on Saccharomyces cerevisiae . II . Effect of radiosensitivity mutations on lethal and mutagenic effects}; Iadgarov KhT; Study of the lethal effect of NMU on radiosensitive strains rad2, rad54 and xrs2 of Saccharomyces cerevisiae has demonstrated that the mutations rad2 and rad54 increase the sensitivity of these strains to low doses of the mutagen . Mutations rad2, rad54 and xrs2 decreases the mutagenic effect of NMU . The study of nature of mutations induced by NMU in ade2 locus has shown that they are mainly the base substitutions . Mutations of radiosensitivity do not influence the nature of NMU-induced mutations in ade2 locus.

Proc Natl Acad Sci U S A, 1981 Jan, 78(1), 435 - 9
Mutant defective in processing of an enzyme located in the lysosome-like vacuole of Saccharomyces cerevisiae; Hemmings BA et al.; Carboxypeptidase Y, a vacuolar enzyme in Saccharomyces cerevisiae, is synthesized as a larger precursor whose apparent molecular mass is approximately 67,000 daltons . We have characterized a recessive mutation, pep4-3, that prevents maturation of this precursor . The accumulated precursor does not possess enzymatic activity . We have shown that the precursor accumulating in the pep4-3 mutant is not produced in a doubly mutant strain that also bears a mutation in the carboxypeptidase Y structural gene that eliminates production of carboxypeptidase Y . We have also shown that a nonsense fragment of carboxypeptidase Y is processed . Although there is evidence that proteinase B can catalyze the conversion of the precursor to a mature form in vitro, nonsense mutations in the structural gene for proteinase B, PRB1, do not affect the levels of carboxypeptidase Y activity, and strains bearing these mutations produce a carboxypeptidase Y of apparently normal size . Hence, proteinase B is not essential for the maturation of carboxypeptidase Y precursor in vivo . The pep4-3 mutation affects at least five vacuolar enzymes . This suggests that there is a processing event common to all of these enzymes.

Can J Genet Cytol, 1981, 23(1), 73 - 9
Pure and mosaic clones--a reflection of differences in mechanisms of mutagenesis by different agents in Saccharomyces cerevisiae; Nasim A et al.; The induction of pure and mosaic clones has been studied in haploid G1 cells of Saccharomyces cerevisiae . Following treatments with ultraviolet light, methyl methanesulfonate, ethyl methanesulfonate, nitrous acid, and N-methyl-N'-nitro-N-nitrosoguanidine, the relative proportions of pure mutant clones varied from 25 to 100% at comparable survival levels . Ultraviolet light and methyl methanesulfonate produced mainly pure mutant clones, whereas ethyl methanesulfonate and nitrous acid produced mainly mosaics at 59 to 100% survival levels . The ratio of pure to mosaic clones induced by nitrosoguanidine fell between these two classes . These results are consistent with a classification of mutagens on the basis of repair and replication-dependent mechanisms of mutagenesis in other organisms . Agents having actions similar to ultraviolet light may produce mainly pure clones through a pre-replicative process involving an error-prone DNA repair process . Others may produce mainly mosaic mutants due to the different nature of DNA lesions which may require a replication-dependent process for fixation of mutations . Preliminary data from combined treatments of mutagens belonging to two different classes (i.e . ultraviolet light and nitrous acid) suggest the possibility of an interaction between these agents, resulting in a higher proportion of pure clones, possibly due to an inducible process . Studies of induced frequencies of pure and mosaic clones may be useful in the characterization of mutagens with functional differences.

Z Allg Mikrobiol, 1981, 21(1), 53 - 5
Effects of chloramphenicol on the thermal profile of Saccharomyces cerevisiae; Madeira-Lopes A et al.; Chloramphenicol decreased the maximum temperature for growth of a petite mutant of Saccharomyces cerevisiae, shifted the ARRHENIUS plot of thermal death to lower temperatures and shortened correspondingly, the ARRHENIUS plot of growth, while an associative thermal profile was maintained . At saturating concentrations (about 5 mg per ml) of chloramphenicol in liquid mineral medium with vitamins and glucose the final maximum temperature for growth was depressed from about 40 degrees C to about 37 degrees C . The results suggested that chloramphenicol acted in the mutant on targets other than mitochondrial ribosomes and that these targets are identical or associated with the death and Tmax sites of the yeast.

Mutat Res, 1981 Jan, 80(1), 91 - 7
Induction of petite "mutants" in an ethidium-resistant strain of Saccharomyces cerevisiae by photoaffinity labeling . Distinction between early and late steps; Fukunaga M et al.; A strain of Saccharomyces cerevisiae (MH41-7B/011) was resistant to petite induction by ethidium bromide at 30 degrees, but was sensitive to induction by photolabeling with ethidium monoazide . These results suggested a defect in the mutant in metabolic activation of ethidium to account for its resistance . Synchronized cultures of both the mutant and the normal parent strains showed a substantial reduction in petite response to photolabeling in stationary phase cells which could not be accounted for by changes in cell penetration of the drug . The use of photolabeling with normal and mutant cells suggested that petite induction can be divided into early and late steps.

Eur J Biochem, 1981 Jan, 113(2), 327 - 31
Synthesis of Saccharomyces cerevisiae catalase A in vitro; Ammerer G et al.; mRNA isolated from cells of the yeast Saccharomyces cerevisiae was translated in the cell-free protein synthesis system from wheat germ . Catalase proteins synthesized were isolated from incubation mixtures by immunoadsorption followed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate . On dodecyl sulfate gels catalase A synthesized by the wheat germ system migrates like catalase A protein synthesized in vivo . Evidence is presented that yeast catalase T and A synthesized in vivo are no glycoproteins . Synthesis of the two catalase proteins in the wheat germ system and dissimilarity of proteolytic fingerprints of the two proteins demonstrate conclusively that catalase T and A are biogenetically unrelated.

J Bacteriol, 1981 Jan, 145(1), 221 - 32
Structure and function of the PHO82-pho4 locus controlling the synthesis of repressible acid phosphatase of Saccharomyces cerevisiae; Toh-e A et al.; pho4 mutants of Saccharomyces cerevisiae, although rare among phosphatase-negative mutants isolated from wild-type strains, were isolated efficiently from pho80, pho85, or pho80 pho85 strains . The distribution of these pho4 mutants over the pho4 locus was determined by analyzing random spores of two- and three-factor crosses . The pho4-4 mutation confers temperature-sensitive synthesis of repressible acid phosphatase . An intragenic suppressor for the pho4-12 allele results in the temperature-sensitive synthesis of repressible acid phosphatase . Recombination between these sites occurs at 1.0 to 3.0%, the highest for any pair of sites within the pho4 locus . All these results strongly indicate that the information of the pho4 locus is translated into a protein . The PHO82 site was mapped inside the pho4 locus by random spore analysis . The order met10-pho4-1PHO82-1-pho4-9 on the right arm of chromosome VI was confirmed by tetrad analysis . Doubly heterozygous diploids, pho3 PHO82c PHO4+/pho3 pho82+ pho4, produce variable amounts of repressible acid phosphatase under repressive conditions depending on the combination of PHO82c and pho4 alleles . This phenomenon may reflect the constitutive production of the pho82+-pho4 product in the repressed condition, which interferes with the function of the PHO82c-PHO4+ product . The earlier model for the function of the PHO82-pho4 cluster, in which the PHO82 site acts as an operator of the pho4 gene, has been revised to a model in which the PHO82 site codes for the part of the pho4 protein that has affinity for the regulatory protein encoded by the pho80 and pho85 genes.

Mol Cell Biol, 1981 Jan, 1(1), 9 - 12
Temperature-sensitive glucosamine auxotroph of Saccharomyces cerevisiae; Ballou L et al.; Temperature-sensitive revertants were isolated from Saccharomyces cerevisiae D-glucosamine auxotrophs previously obtained in this laboratory (W . L . Whelan and C . E . Ballou, J . Bacteriol . 124:1545-1557, 1975) . The auxotrophs lack the enzyme 2-amino-2-deoxy-D-glucose-6-phosphate ketol-isomerase (EC 5.3.1.19), and the revertants appear to be temperature sensitive in the formation of enzyme activity . The enzyme they produce under permissive conditions decays in activity at a rate comparable to that of the wild-type enzyme, and it has similar kinetic properties . The homozygous diploid mutant fails to sporulate at the nonpermissive temperature . Temperature shift experiments were carried out in an effort to determine what effect glucosamine deficiency had on mannoprotein secretion as reflected in the formation of external asparaginase . Although the results were complicated by the slow decay of the residual ketol-isomerase activity, they did show that mannoprotein synthesis or secretion was altered when the internal pool of D-glucosamine was depleted.

Mol Cell Biol, 1981 Jan, 1(1), 51 - 7
Characterization of a 40S ribosomal subunit complex in polyribosomes of Saccharomyces cerevisiae treated with cycloheximide; Helser TL et al.; Under specific conditions cycloheximide treatment of Saccharomyces cerevisiae caused the accumulation of a type of polyribosome called "halfmer." Limited ribonuclease digestion of halfmers released particles from the polyribosomes identified as 40S ribosomal subunits . The data demonstrated that halfmers are polyribosomes containing an additional 40S ribosomal subunit attached to the messenger ribonucleic acid . Protein gel electrophoretic analysis of halfmers revealed numerous nonribosomal proteins . Two of these proteins comigrate with subunits of yeast initiation factor eIF2.

Cancer Detect Prev, 1981, 4(1-4), 53 - 7
Recombinogenic activity of fresh cigarette smoke in Saccharomyces cerevisiae; Gairola CC et al.; A procedure for determining the effect of fresh cigarette smoke on gene conversion in yeast . Saccharomyces cerevisiae D7, is described . Cigarette smoke, generated by a 2-sec, 40-ml puff, once per minute, was puffed into an open-end tube . The smoke was drawn through an exposure vessel containing a continuously stirred, stationary-phase yeast cell suspension, 1-58 sec after generation . Frequency of gene conversion was estimated in samples taken at intervals after the start of exposure . Under these conditions, a five-fold increase in mitotic gene conversion in yeast strain D7 was obtained from exposure to 20 puffs of fresh whole smoke from University of Kentucky Reference Cigarettes (2R1), to 75 puffs from the gas phase of these cigarettes, and to 45 puffs from an acetate filter version (2R1F) . Selective removal of genetically active components by acetate filters is suggested since the reduction in recombinogenic activity (55%) is greater than the reduction in total particulate matter yield (25%) of the cigarette . The results indicate that 1) the procedure provides a practical bioassay for determining the effects of fresh smoke on gene conversion in yeast, without external metabolic activation; 2) the gas phase of smoke has recombinogenic activity; and 3) standard acetate filters may selectively remove genetically active components of cigarette smoke.

C R Seances Soc Biol Fil, 1981, 175(6), 835 - 9
{Possible transfer between sarcomatous mouse cells (BP8) and yeasts (Saccharomyces cerevisiae, whole bodies and protoplasts)}; Miegeville M et al.; From our observation in vitro, we can suggest that : a direct contact between sarcomatous cells and physiologically active yeasts appears to be necessary for the transfer of the radioactive labelling; the presence of a filter with pores of 1.2 micrometer diameter prevents passage of fragments of DNA or RNA between the cells; this transfer is a very small fact, but implies about the third of the yeasts.

J Mol Appl Genet, 1981, 1(3), 239 - 44
The nucleotide sequences of the actin genes from Saccharomyces carlsbergensis and Saccharomyces cerevisiae are identical except for their introns; Nellen W et al.; The actin gene from yeast Saccharomyces carlsbergensis was cloned in Escherichia coli and its complete nucleotide structure was determined . A comparison of its DNA sequence with that of the related yeast species Saccharomyces cerevisiae revealed that the coding as well as the 5'- and 3'-untranslated regions are identical . The intron, although at the same location in the two genes, differs in three positions . There is one deletion (or insertion), one transition, and one transversion . These are clustered within and around an oligo(dA) stretch of 14 (or 13) residues . Our observations identify the intron as the fastest evolving segment of this eukaryotic gene.

Mol Gen Genet, 1981, 182(3), 456 - 61
Construction of hybrid plasmids containing the lysA gene of Escherichia coli: studies of expression in Escherichia coli and Saccharomyces cerevisiae; Chenais J et al.; The lysA gene of Escherichia coli has been cloned from a lambda transducing phage on various plasmids, present in different copy numbers in bacterial cells . Synthesis of the product of this gene, diaminopimelate (DAP)-decarboxylase, and its regulation have been studied . Expression does not follow a simple gene dosage effect, maximal expression already being obtained with a six-copy plasmid . This result suggests that either a positive or an autogenous regulatory mechanism is involved . We also used one of the hybrid plasmids to look for expression of the bacterial lysA gene in Saccharomyces cerevisiae . The results indicate that the product of the E . coli gene is not actively translated in yeast.

Mol Gen Genet, 1981, 182(1), 159 - 63
Analysis of mutations affecting Ty-mediated gene expression in Saccharomyces cerevisiae; Ciriacy M et al.; Yeast translocatable, Ty, elements can cause constitutive synthesis of the glucose-repressible alcohol dehydrogenase (ADHII) when inserted upstream from the 5' end of the structural gene, ADR2 . These insertion mutations, ADR3c, are unstable and give rise to secondary ADHII- mutations . The majority of such mutants, adr3, can be attributed to excision of the insertion sequence, leaving behind a single copy of the delta-sequence which occurs as a direct repeat at the ends of the Ty elements . A few adr3 mutants appear to be generated by DNA-rearrangements in the vicinity of the Ty insertion . The occurrence of recessive mutants, tye, which are unlinked to ADR2 indicates that the constitutive expression of ADR2 caused by the Ty insertions requires the function of trans-acting genes . These results support the idea that regulation of Ty-linked ADR2 is actively mediated by the insertion sequence and is probably not due to a mere disruption of the wild-type controlling site.

Acta Microbiol Pol, 1981, 30(2), 111 - 21
Isolation and properties of elongation factor 1 from Saccharomyces cerevisiae; Palen E et al.; Polypeptide elongation factor 1 was isolated from yeast postribosomal supernatant . The highly purified factor was resolved on Ultrogel AcA-44 into two complementary fractions . One of these fractions contained two different polypeptide chains corresponding to a Ts-like elongation factor EF-1 beta gamma . The other fraction represented the light form of the factor, designated EF-1 alpha, with a molecular weight of approximately 50,000 . The obtained results indicate that EF-1 from lower eukaryotes is also composed of three distinct polypeptides.

J Biol Chem, 1980 Dec 25, 255(24), 11892 - 5
Effect of glucosylation of lipid intermediates on oligosaccharide transfer in solubilized microsomes from Saccharomyces cerevisiae; Trimble RB et al.; Glc3Man9GlcNAc2-P-P-dolichol and Man9GlcNAc2-P-P-dolichol isolated from Saccharomyces cerevisiae are substrates for the N-glycosylation of endogenous proteins in Triton X-100-solubilized yeast microsomes . The solubilized oligosaccharide transferase requires Mn2+ for activity; neither Mg2+ nor Ca2+ is an effective substitute . The pH optimum of the transfer reaction is between 6.5 and 7.5 . Unlike animal systems, which utilize glucosylated oligosaccharide-lipid to a much greater extent than the unglucosylated species as a donor in the transferase rection, yeast extracts transfer more than 70% of Glc3Man9GlcNAc2 and Man9GlcNAc2 from their respective oligosaccharide-lipids to proteins . However, the rate of N-glycosylation in vitro is approximately 25-fold faster with Glc3Man9GlcNAc2-P-P-dolichol than with Man9GlcNAc2-P-P-dolichol . The apparent Km value for the glucosylated species is 75 nM, while that for the unglucosylated glycolipid is 55 nM.

J Biol Chem, 1980 Dec 25, 255(24), 11704 - 9
RNA-dependent ATPase from Saccharomyces cerevisiae; Belhadj O et al.; A new RNA-dependent ATPase has been isolated from yeast chromatin extracts and partially characterized . The protein has a sedimentation coefficient of about 7 S . The enzyme hydrolyzes specifically ATP (or dATP) to ADP (or dADP) and Pi in the presence of Mg2+ or Mn2+ ions and requires a single-stranded polynucleotide as cofactor . The order of efficiency of synthetic polymers is poly(rU) > poly(rI) greater than or equal to poly(dU) > poly(rA) greater than or equal to poly(rC) . Among natural polymers, single-stranded DNA and poly(rA)-containing mRNA from yeast are also active but less so than poly(rU) . The enzyme exhibits a pH optimum of 8 and is fully inhibited by 0.25 M NaCl . The Km for ATP is0.2 mM . The resemblance between this ATPase and DNA-dependent ATPases from other sources, as well as the termination factor rho, is discussed.

Nucleic Acids Res, 1980 Dec 11, 8(23), 5779 - 94
The structure of the yeast ribosomal RNA genes . I . The complete nucleotide sequence of the 18S ribosomal RNA gene from Saccharomyces cerevisiae; Rubtsov PM et al.; The cloned 18 S ribosomal RNA gene from Saccharomyces cerevisiae have been sequenced, using the Maxam-Gilbert procedure . From this data the complete sequence of 1789 nucleotides of the 18 S RNA was deduced . Extensive homology with many eucaryotic as well as E . coli ribosomal small subunit rRNA (S-rRNA) has been observed in the 3'-end region of the rRNA molecule . Comparison of the yeast 18 S rRNA sequences with partial sequence data, available for rRNAs of the other eucaryotes provides strong evidence that a substantial portion of the 18 S RNA sequence has been conserved in evolution.

Biochim Biophys Acta, 1980 Dec 4, 616(2), 271 - 82
Asparaginase II of Saccharomyces cerevisiae: inactivation during the transition to stationary phase; Pauling KD et al.; Asparaginase II (L-asparagine amidohydrolase, EC 3.5.1.1) activity of cells from stationary phase cultures of Saccharomyces cerevisiae is very low . When these cells are inoculated into minimal medium, asparaginase II specific activity rises rapidly and reaches a maximum after 9-10 h . During the next 2.5-3 h, a rapid decrease in asparaginase II specific activity occurs . The enzyme does not appear to be secreted into the medium or to be reabsorbed into the cell . Addition of protease inhibitors at the time of maximum activity partially or totally prevents the loss of asparaginase II . L-1-Tosylamide-2-phenylethyl chloromethyl ketone decreases the rate of loss . The sulfhydryl reagents p-hydroxymercuribenzoate and iodoacetamide inhibit the loss of asparaginase II . However, addition of EDTA causes a further increase in activity . This increase is due to de novo protein synthesis . The effect of EDTA can be reversed by the addition of Zn2+ . The most likely explanation for the rapid loss of asparaginase II is proteolytic degradation by a Zn2+-dependent, thiol protease or peptidase.

Genetics, 1980 Dec, 96(4), 859 - 76
Diploid spore formation and other meiotic effects of two cell-division-cycle mutations of Saccharomyces cerevisiae; Schild D et al.; The meiotic effects of two cell-division-cycle mutations of Saccharomyces cerevisiae (cdc5 and cdc14) have been examined . These mutations were isolated by L.H . HARTWELL and his colleagues and characterized as defective in mitosis, causing a temperature-sensitive arrest in late nuclear division . When subjected to the restrictive temperature in meiosis, diploid cells homozygous for either of these mutations generally proceeded through premeiotic DNA synthesis and commitment to meiotic levels of recombination, but then arrested at a stage following spindle pole body (SPB) duplication and separation . The two SPBs lacked the interconnection by spindle microtubules typical of the complete meiosis I spindle . Challenge of these homozygotes by a semi-restrictive temperature often caused the production of asci containing two diploid spores . Genetic analysis of the viable pairs of spores revealed that each spore had become homozygous for centromere-linked markers significantly more frequently than for distal markers, indicating that the two spores each contained pairs of sister centromeres that had co-segregated in the reductional division of meiosis I . Ultrastructural analysis of the cdc5 homozygote demonstrated that these cells had completed meiosis I and formed two meiosis II spindles, but that the latter remained unusually short . This resulted in the encapsulation of both poles of each spindle within a single spore wall . These mutations therefore are defective in both meiotic divisions, as well as in the mitotic division described originally.

Genetics, 1980 Dec, 96(4), 819 - 39
The origin of spontaneous mutation in Saccharomyces cerevisiae; Quah SK et al.; Characterization of two antimutator loci in yeast shows that both are members of the same mutagenic repair system known to be responsible for almost all induced mutation (LAWRENCE and CHRISTENSEN 1976, 1979a,b; PRAKASH 1976) . One of the these newly isolated antimutator mutations is an allele of rev3 (LEMONTT 1971b) . Two other alleles of rev3 were tested and were also found to be antimutators . Double mutants carrying rev3 and mutator mutations of rad3, rad51 or rad18 are like rev3 single mutants with respect to spontaneous mutation rate, supporting the hypothesis (HASTINGS, QUAH and VON BORSTEL, 1976) that many mutators in yeast act by channelling spontaneous lesions from accurate to mutagenic repair . However, the enhanced mutation rate seen in a radiation-resistant mutator mutant mut1 is not dependent on REV3, but is dependent on another gene designated ANT1 . An additive effect on the reduction in spontaneous mutation, seen in the ant1 rev3 double-mutant strain, leads to the conclusion that at least 90% of spontaneous mutations seen in the wild type are caused by mutagenic repair of spontaneous lesions.

Antimicrob Agents Chemother, 1980 Dec, 18(6), 863 - 7
Binding of cycloheximide to ribosomes from wild-type and mutant strains of Saccharomyces cerevisiae; Stocklein W et al.; Cycloheximide bound to cytoplasmic (80S) ribosomes of the yeast Saccharomyces cerevisiae with an association constant (Ka) of 2.0 (+/- 0.5) x 10(7) M-1 . The number of binding sites found per ribosome was between 0.4 and 0.6; it was reduced by high-salt treatment of ribosomes 60S particles prepared in the presence of high salt had a lower affinity (Ka: 5.5 {+/- 0.5} x 10(6) M-1) than did 80S ribosomes, but a greater proportion of particles (0.8) were able to bind . No specific binding to 40S subunits was observed . The addition of supernatant fractions (S100, high-salt wash fraction) increased the number of binding sites found per 80S ribosome up to 0.8, leaving the association constant unchanged . In contrast, the affinity of 60S subunits was enhanced to a Ka value of 3.5 x 10(-7) M-1 by the addition of supernatant fractions, whereas the number of binding sites stayed constant . A model to explain these facts is proposed . 80S ribosomes, as well as 60S subunits of strain cy32, which is highly resistant to cycloheximide and altered in ribosomal protein L29 (18), showed a drastically reduced affinity for the drug (Ka values of 2.0 x 10(6) M-1).

J Cell Sci, 1980 Dec, 46, 341 - 52
The influence of the microtubule inhibitor, methyl benzimidazol-2-yl-carbamate (MBC) on nuclear division and the cell cycle in Saccharomyces cerevisiae; Quinlan RA et al.; Methyl benzimidazol-2-yl-carbamate (MBC), at a concentration of 100 microM, has a pronounced effect on the growth of Saccharomyces cerevisiae, resulting in the accumulation of cells as large doublets . We have determined a specific execution point for the effect of MBC on the yeast cell cycle, and have shown that this execution point is between the cycle events of spindle pole body duplication and spindle pole body separation . An ultrastructural examination of the MBC-treated cells revealed the absence of cytoplasmic and spindle microtubules . MBC treatment also produced an altered spindle pole body morphology, causing the disappearance of the outer component . Nuclear size was also markedly increased in the MBC-induced doublet cells, although the septa were completely absent from these doublet cells . It is proposed that MBC inhibits microtubule polymerization, rather than causing the depolymerization of stable microtubules.

Gene, 1980 Dec, 12(1-2), 1 - 10
Expression of the HIS3 gene of Saccharomyces cerevisiae in polynucleotide phosphorylase-deficient strains of Escherichia coli K-12; Kasunic DA et al.; The PstI and BamHI fragments, containing the HIS3 (imidazoleglycerol phosphate dehydratase) gene of yeast obtained from pYehis2, and the ColE1-derived plasmid pBR322 were ligated in vitro and used to transform hisB463 strains of Escherichia coli K-12 . Expression of the cloned HIS3 gene from yeast was markedly enhanced (3--5-fold) in polynucleotide phosphorylase (pnp)-deficient strains of E . coli . The levels of both HIS3 and plasmid-encoded mRNAs were increased in pnp- strains carrying the chimeric plasmids, whereas there was little difference in the levels of pBR322-specific mRNAs in pnp+ and pnp- strains . This increase in HIS3 mRNA appeared to be related to specific stabilization of the eukaryotic message due to its unique structural features, since the half-life of the HIS3 mRNA increased from 1.5 to 18.7 min, whereas no increase in the half-lives of pBR322 vehicle mRNAs was observed . A physical map of the plasmid pYehis2 was constructed using restriction endonuclease and molecular cloning techniques.

J Bacteriol, 1980 Dec, 144(3), 1143 - 51
Identification of an actin-like protein and of its messenger ribonucleic acid in Saccharomyces cerevisiae; Water RD et al.; We have identified a yeast protein that resembles actins from other eucaryotes in its tight binding to pancreatic deoxyribonuclease I, its copolymerizaton with purified muscle actin, its one-dimensional peptide map, and its apparent polymerization into 7-nm filaments . The yeast actin-like protein yielded a single spot on two-dimensional polyacrylamide gel electrophoresis, suggesting that a single protein species was present . On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the actin-like protein had an apparent molecular weight of 45,000 compared with 42,000 for muscle actin . In an attempt to identify the messenger ribonucleic acid coding for the actin-like protein, yeast polyadenylic acid-rich ribonucleic acid was translated in wheat germ and reticulocyte cell-free protein-synthesizing systems . The actin-like protein was identified among the translation products of the reticulocyte system by its tight binding to deoxyribonuclease I, its comigration with the in vivo-synthesized actin-like protein during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, an the similarity of its peptide map to that of the in vivo-synthesized protein . A yeast protein synthesized in the wheat-germ system was also found to bind to deoxyribonuclease I and to copolymerize with muscle actin . However, its apparent molecular weight was about 35,000, suggesting that it was a product either of incomplete translation or of proteolytic cleavage of the actin-like protein.

J Bacteriol, 1980 Dec, 144(3), 1113 - 8
Isolation and characterization of temperature-sensitive mak mutants of Saccharomyces cerevisiae; Guerry-Kopecko P et al.; The K1 killer plasmid of Saccharomyces cerevisiae is a 1.5-megadalton linear double-stranded ribonucleic acid molecule . Using simplified screening and complementation procedures, we have isolated mutants in three chromosomal genes that are temperature sensitive for killer plasmid maintenance or replication . One of these genes, mak28-1, was located on chromosome X . Two of the temperature-sensitive mutants rapidly lost the wild-type killer plasmid of A364A during spore germination and outgrowth at nonpermissive temperatures, but during vegetative growth, they only lowered the plasmid copy number . These two mutants did not lose two other wild-type K1 killer plasmids, indicating a heterogeneity of the killer plasmids in laboratory yeast strains.

Gene, 1980 Dec, 12(1-2), 41 - 9
3 micron DNA - an extrachromosomal ribosomal DNA in the yeast Saccharomyces cerevisiae; Larionov VL et al.; A new class of extrachromosomal DNA which consists predominantly of covalently closed molecules with lengths around 3 micron, has been detected in Saccharomyces cerevisiae strain 6-1G-P188 from the Peterhof collection . Restriction analysis of the 3 micron DNA as well as of recombinant plasmids carrying HindIII fragments of the 3 micron DNA permitted construction of a physical map of the new extrachromosomal DNA species, and detection of two types differing by one EcoRI restriction site . Molecular hybridization, as well as comparison of the restriction maps, revealed the complete structural identity of the 3 micron DNA with a chromosomal repetitive unit of rDNA containing the genes for 25 S, 18 S, 5.8 S and 5 S rRNAs.

Biochem J, 1980 Nov 15, 192(2), 659 - 64
Membrane proteins associated with amino acid transport by yeast (Saccharomyces cerevisiae); Woodward JR et al.; Cells of the wild-type yeast (Saccharomyces cerevisiae) strain Y185, grown under conditions that de-repress the formation of a general amino acid permease ('Gap') system, bind delta-N-chloroacetyl{1-(14)C}ornithine; L- and D-amino acid substrates of the general amino acid permease system protect against this binding . The protein responsible is released from the cells by homogenization or by preparation of protoplasts; it is not released by osmotic shock . This protein is virtually absent from the wild-type strain when it is grown under conditions that repress the general amino acid permease system, and is also absent from a Gap- mutant Y185-His3, selected by its resistance to D-amino acids . This mutant and repressed wild-type cells also fail to form a number of membrane proteins elaborated by de-repressed wild-type cells . It is possible that all these proteins are components of the general amino acid permease system.

Biochemistry, 1980 Nov 11, 19(23), 5456 - 62
Melting of Saccharomyces cerevisiae 5S ribonucleic acid: ultraviolet absorption, circular dichroism, and 360-MHz proton nuclear magnetic resonance spectroscopy; Luoma GA et al.; The heat-induced melting of yeast 5S RNA and tRNAPhe has been monitored by UV, CD, and 360-MHz 1H NMR spectroscopy in order to determine the extent of base stacking and base pairing in the native and denatured structures . In the presence of Mg2+, the optical data indicate less than or equal to 40 base pairs in native yeast 5S RNA, a 60:40 ratio of GC to AU base pairs, with more single-stranded stacking and a slightly less stable structure (half-melted at 67 degrees C) than for tRNAPhe (half-melted at 71 degrees C) . In the absence of Mg2+, the NMR results identify a minimum of approximately 32 base pairs at 25 degrees C (increasing to a minimum of approximately 35 base pairs in the presence of Mg2+), of which more than half are still intact at 48 degrees C . The native structure (25 degrees C) shows only minor dependence upon Mg2+ concentration, and no denatured forms could be detected . Finally, the present results support a previously proposed cloverleaf secondary structure for eukaryotic 5S RNA.

J Biol Chem, 1980 Nov 10, 255(21), 10232 - 8
Characterization of large oligosaccharide-lipids synthesized in vitro by microsomes from Saccharomyces cerevisiae; Trimble RB et al.; Conditions are described for optimizing the synthesis of large oligosaccharide-lipids in microsomal preparations from Saccharomyces cerevisiae . On incubating microsomes, with GDP-{14C}Man, the major product obtained was Man9GlcNAc2-P-P-dolichol, but when both GDP-{14C}Man and UDP-{3H}Glc were present in the incubation mixture about half of the Man9GlcNAc2 was elongated to Glc3Man9GlcNAc2-P-P-dolichol . Unlike particulate fractions from mammalian systems, little glucosylation of the yeast microsomal oligosaccharide-lipid was obtained when the concentration of UDP-Glc was less than 10 microM, but the synthesis of this product could be maximized by raising the concentration of UDP-Glc to 50 microM . Analysis of the yeast Man9GlcNAc2 species confirmed that 8 of the 9 mannose residues could be released with alpha-mannosidase, while the remaining mannosyl residue was in the core trisaccharide, Manbeta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc . Treatment of Glc3Man9GlcNAc2 with alpha-mannosidase released 5 of 9 mannose residues and yielded Glc3Man4GlcNAc2 . This product appeared to be identical with that obtained in parallel experiments with double labeled oligosaccharide-lipid synthesized in oviduct microsomes . Streptomyces plicatus endo-beta-N-acetylglucosaminidase H (Endo-H) treatment of yeast microsomal glycoproteins that were labeled with sugar nucleotides established that 15% of the label was associated with N-linked oligosaccharides . The remaining labeled sugars were released with alkali, indicating that they were linked to serine or threonine . Based on the size and distribution of {3H}glucose and {14C}mannose in the Endo-H-released oligosaccharides, it was concluded that Glc3Man9GlcNAc2 was the primary species transferred to proteins in the yeast system.

Mutat Res, 1980 Nov, 73(1), 69 - 79
Differential effect of UV irradiation on induction of intragenic and intergenic recombination during commitment to meiosis in Saccharomyces cerevisiae; Machida I et al.; A comparison was made between the induction of intragenic and intergenic recombinations during meiosis in a wild-type diploid of Saccharomyces cerevisiae . Under non-irradiated normal conditions, production of both intragenic and intergenic recombinants greatly increased in the cells with commitment to meiosis . The susceptibility of cells to the induction of both the spontaneous intra- and intergenic recombinations in meiotic cells was similar . However, under condition of UV irradiation, there were striking differences between intra- and intergenic recombinations . Susceptibility to induction of intragenic recombination by UV irradiation was not enhanced at meiosis compared with mitosis, and was not altered through commitment to meiotic processes . In contrast, however, susceptibility to the induction of intergenic recombination by UV irradiation was enhanced markedly during commitment to meiosis compared with mitosis . Genetic analysis suggested that the enhanced susceptibility to recombination during meiosis is specifically concerned with reciprocal-type recombination (crossing-over) but not non-reciprocal-type recombination (gene conversion) . Hence it is concluded that the meiotic process appears to be intimately concerned with the mechanism(s) of induction of recombination, especially reciprocal-type recombination.

Mutat Res, 1980 Nov, 73(1), 59 - 68
Induction of spontaneous and UV-induced mutations during commitment to meiosis in Saccharomyces cerevisiae; Machida I et al.; Inductions of reversions of nonsense, missense and frameshift-type mutations were investigated in a diploid cell population of Saccharomyces cerevisiae during commitment to meiosis, by using the medium-transfer technique from sporulation medium to vegetative medium . The yields of spontaneous reverse mutations obtained from the cells that were committed to different stages during meiosis were rather constant irrespective of the alleles tested, although the yields of both intergenic and intragenic recombinations markedly increased . The susceptibilities to UV-induced reverse mutations examined during commitment to meiosis were not changed appreciably . It is concluded that induction of base-change-type mutations in meiosis is not essentially different from that in mitosis.

J Biochem (Tokyo), 1980 Nov, 88(5), 1419 - 23
Occurrence of low molecular weight O-acetylserine sulfhydrylase in the yeast Saccharomyces cerevisiae; Yamagata S; Studies with crude preparations obtained from a cysteine auxotroph of Saccharomyces cerevisiae showed that O-acetylserine sulfhydrylase could be separated from O-acetylhomoserine sulfhydrylase by chromatography on a DEAE-cellulose column and centrifugation in a sucrose density gradient . On the basis of sedimentation distance, the molecular weights of these enzymes were calculated to be about 99,000 and 182,000, respectively . The former did not react with the amino acid substrate of the latter, and vice versa . The wild-type strain was also demonstrated to possess O-acetylserine sulfhydrylase (molecular weight: about 96,000), in addition to a large amount of O-acetylserine-O-acetylhomoserine sulfhydrylase (Yamagata et al . (1974) J . Biochem . 75, 1221).

Proc Natl Acad Sci U S A, 1980 Nov, 77(11), 6329 - 33
Autonomously replicating sequences in Saccharomyces cerevisiae; Chan CS et al.; A method is presented for isolating DNA segments capable of autonomous replication from Saccharomyces cerevisiae chromosomal DNA based on the differential transforming ability of autonomously replicating plasmids and nonreplicating plasmids . DNA plasmids that are capable of self-replication in yeast transform yeast spheroplasts at about 1000-fold higher frequency than nonreplicating plasmids . We have cloned from total yeast DNA a number of DNA segments that permit the pBR322 plasmid carrying the yeast LEU2 gene to replicate autonomously . These plasmid clones are characterized by their ability to transform Leu- spheroplasts to Leu+ at a high frequency and their ability to replicate autonomously . Analysis of the insert DNAs carried in some of these self-replicating plasmids divides them into two categories: those that are unique in the yeast genome and those that are repetitive.

J Bacteriol, 1980 Nov, 144(2), 852 - 5
Transposed LEU2 gene of Saccharomyces cerevisiae is regulated normally; Kohlhaw GB et al.; The repression of beta-isopropylmalate dehydrogenase, the LEU2 gene product, by leucine and leucine plus threonine was unaffected by the transposition of LEU2 from its original locus on chromosome III to a new locus within the ribosomal deoxyribonucleic acid gene cluster on chromosome XII . Since the expression of the LEU2 gene is probably controlled at a pretranslational level, we conclude that the recombinant plasmid used for transformation carries regulatory information in addition to LEU2 structural information.

J Bacteriol, 1980 Nov, 144(2), 826 - 9
Photorepair of ultraviolet-induced petite mutational damage in Saccharomyces cerevisiae requires the product of the PHR1 gene; Green G et al.; A wild-type (phr+) diploid yeast strain showed photorepair of petite mutational damage, whereas a photoreactivation-deficient (phr1/phr1) diploid strain did not, indicating that the PHR1 gene product was required for mitochondrial photorepair.

J Antibiot (Tokyo), 1980 Nov, 33(11), 1369 - 75
Isolation and partial characterization of mutants of Saccharomyces cerevisiae altered in sensitivities to lethal effects of bleomycins; Moore CW; Two of eight mutants (bmr) isolated in Saccharomyces cerevisiae on the basis of their increased resistance to lethal effects of antitumor bleomycins (BM), and about two-thirds of 180 yeast mutants (bms) isolated on the basis of their increased sensitivities to cell-killing by phleomycins (PM) or BM were sensitive to one or more of the agents UV, X-rays or hydrogen peroxide, Thus these mutants are likely to be altered in processes acting directly or indirectly on DNA damage . The remaining six bmr mutants and approximately 60 bms mutants appear as resistant as the parent strain to cell-killing by UV or X-rays, and are likely therefore, to be altered in cell wall or membrane function . A genetic basis for the phenotypes of some of the bmr and bms mutants has been established.

J Biol Chem, 1980 Oct 25, 255(20), 9821 - 7
Assembly of the mitochondrial membrane system . Complete restriction map of the cytochrome b region of mitochondrial DNA in Saccharomyces cerevisiae D273-10B; Nobrega FG et al.; The cytoplasmic petite (rho-) mutant DS400/A12 has been obtained from the wild type strain of Saccharomyces cerevisiae D273-10B/A21 . The DS400/A12 clone has a mitochondrial genome with a 7.6-kilobase pair, tandemly repeated segment of DNA . Genetic tests indicate that DS400/A12 contains all the cob1 and cob2 markers of the cytochrome b gene . The gene has been further dissected by mutagenesis of DS400/A12 and selection of secondary rho- clones with simpler genotypes . Restriction analysis of the mtDNAs of the rho- clones was used to construct the complete restriction map of the cytochrome b region and to map the mutations within narrowly defined physical limits . The cytochrome b mutants scatter over a maximal distance of 3.3 kilobase pairs . All the mutations assigned previously to the cob2 locus are found between 71.6 and 73.2 units . The cob1 mutations are located between 74.6 and 76.3 units . The estimated distance between the two loci is at least 1 kilobase pair.

Biochim Biophys Acta, 1980 Oct 16, 602(1), 201 - 6
Mitochondrial control of cell surface characteristics in Saccharomyces cerevisiae; Evans IH et al.; Defects in the inner mitochondrial membrane of petite mutants of yeast resulted not only in respiratory deficiency, but also in changes in cell surface characteristics . These were (1) concanavalin A agglutinability, (2) cell movement in a biphasic polymer system, (3) cell adhesion . Genetic analysis indicated that the control exerted by the mitochondria was on nuclear genes or on the products of these genes which were presumably specifying cell surface components . These findings ascribe a new role to mitochondria but also have implications for neoplastic transformation.

Eur J Biochem, 1980 Oct, 111(2), 357 - 67
Spontaneous dissociation of a cytochrome core and a biglobular flavoprotein after mild trypsinolysis of the bifunctional Saccharomyces cerevisiae flavocytochrome b2; Gervais M et al.; Saccharomyces cerevisiae flavocytochrome b2 is known as a bifunctional enzyme which behaves as the association of an FMN flavodehydrogenase with its specific acceptor, a b5-like cytochrome . Mild trypsinolysis gives rise to three complementary fragments (n, X, beta'), both prosthetic groups being still bound . After such proteolysis the separation of a biglobular flavoprotein domain (carrying FMN) from a cytochrome domain (with the heme) is obtained by molecular sieving under non-denaturing conditions . The marked lack of affinity between the tetrameric flavoprotein (X, beta')4 and the monomeric cytochrome core (n) leads to the hypothesis that the two domains are not tightly associated in the native molecule and might more relative to each other . Their respective mobility is possibly required for the catalytic mechanism . The comparison with previous trypsinolysis studies on the flavocytochrome b2 from Hansenula anomala suggests the presence of two common zones of hypersensitivity to proteases, along the protomeric polypeptide chain, and strongly supports the validity of the triglobular model for both flavocytochromes.

Eur J Biochem, 1980 Oct, 111(1), 161 - 9
Cytochrome b-565 in Saccharomyces cerevisiae: use of mutants in the cob- box region of the mitochondrial DNA to study the functional role of this spectral species of cytochrome b . 2 . Relationship between energetic data and cytochrome b-565 content; Chevillotte-Brivet P et al.; A wild-type strain of Saccharomyces cerevisiae and temperature-dependent revertants of isonuclear box mutants partially or completely devoid of cytocheomr b-565, were used to study the role of this cytochrome in oxidative phosphorylation . At the mitochondrial level, the phosphorylating data and the succinate oxidase activity at three different temperatures (16 degrees C, 28 degrees C and 36 degrees C) were measured in these strains showing various cytochrome b-565 contents . It is concluded that this cytochrome b-565 is not in the main pathway of the electron transfer chain . At the optimum growth temperature (28 degrees C), the measurements of the P/O ratio for the wild phenotype strains, with ethanol as substrate, led to the conclusions that two phosphorylation sites of the respiratory chain are functional in these strains . The growth yields for wild phenotype strains and revertants grown in vivo in complex media, with ethanol or galactose as the energy source (at 16 degrees C, 28 degress C and 36 degrees C), were compared with the cytochrome b-565 content . The growth yields showed small variations if compared to the reference strain, when the cytochrome b-565 content was greatly diminished or absent . Thus the ATP production at side II is independent of the cytochrome b-565 content . Cytochrome b-565 does not play an essential role in oxidative phosphorylation.

Eur J Biochem, 1980 Oct, 111(1), 151 - 9
Cytochrome b-565 in Saccharomyces cerevisiae: use of mutants in the cob-box region of the mitochondrial DNA to study the functional role of this spectral species of cytochrome b . 1 . Measurements of cytochromes b-562 and b-565 and selection of revertants devoid of cytochrome b-565; Meunier-Lemesle D et al.; In order to study the functional role of the spectral species of cytochrome b-565 observed in mitochondria, genetically manipulated strains of Saccharomyces cerevisiae have been used . Strains have been found which are devoid of cytochrome b-565 under certain conditions and which nevertheless are able to grow on a respirable substrate . Two different methods have been used to determine the cytochrome b-565 content: anaerobic titrations and antimycin-A-induced reduction of cytochrome b-565 . Both yield the same results.

J Bacteriol, 1980 Oct, 144(1), 74 - 81
Fluctuation in polyadenylate size and content in exponential- and stationary-phase cells of Saccharomyces cerevisiae; Sogin SJ et al.; Stationary-phase cells of Saccharomyces cerevisiae were found to have a reduced polyadenylate {poly(A)} content as compared with exponential-phase cells . A sizing procedure for poly(A) was devised to distinguish between alternative hypotheses to explain this reduction . Two major size classes of poly(A) were found . The decreased representation of the larger of the two classes accounted for the majority of the poly(A) loss . The remainder of the loss was accounted for by fewer poly(A)-containing sequences . The smaller of the two poly(A) classes was apparently not of mitochondrial origin and may be added transcriptionally.

Genetics, 1980 Oct, 96(2), 315 - 20
Precise mapping of the homothallism genes HML and HMR in Saccharomyces cerevisiae; Klar AJ et al.; The HML and HMR loci carry unexpressed copies of MATa and MAT alpha information, and a replica of that information is transposed to MAT during mating-type interchange in Saccharomyces yeasts . A negative control mechanism keeps silent the information located at the HML and HMR loci . We mapped these loci by constructing strains in which these loci are expressed . In these strains, the mating type of the segregants is dependent upon the allele at HML and HMR . This novel approach is independent of their switching function . HML is located on the left arm of chromosome III distal to his4 by about 26.8 centimorgans (cM) . HMR maps on the right arm of the same chromosome distal to thr4 by about 39.8 cM and proximal to MAL2 by about 1.0 cM . The results allow the exact placement of these loci and are in accord with the observations made by Harashima and Oshima (1976).

J Bacteriol, 1980 Oct, 144(1), 92 - 6
Immunochemical studies of the mannans of Saccharomyces cerevisiae X2180-1A-5 and Saccharomyces cerevisiae 4484-24D-1 mutant strains, with special reference to their phosphate content; Okubo Y et al.; The mannans from Saccharomyces cerevisiae mutant strains X2180-1A-5 and 4484-24D-1, both of which were shown to contain small amounts of phosphate (less than 0.2%), were fractionated on a column of diethylaminoethyl-Sephadex into five subfractions designated as fractions I to V . These subfractions contain different amounts of phosphate, ranging from 0.03 to 0.09 (strain X2180-1A-5) and from 0.01 to 0.17% (strain 4484-24D-1) . Fractions I to IV from strain X2180-1A-5 showed nearly identical precipitin activities against the homologous anti-whole cell serum, whereas fraction V, containing the largest amount of phosphate and protein among this mannan subfraction series, showed unexpectedly weaker precipitin activity than those of the other fractions . A synthetic mannan consisting or consecutive alpha-1 leads to 6-linked D-mannopyranosyl residues was found to be cross-reactive with all the mannan subfractions of strain X2180-1A-5 against anti-X2180-1A-5 serum . On the other hand, antibody-precipitating activities of the mannan subfractions of the latter strain were proportional to their phosphate content, although the increments of precipitated antibody nitrogen among the subfractions were quite small . However, fraction V of this mannan subfraction series, containing the largest amounts of phosphate and protein, showed lower precipitin activity than did the other four fractions . These findings indicate that mannans containing no phosphate or relatively small amounts of phosphate, such as those investigated in the present study, are less heterogeneous in the densities of the branching moieties than are highly phosphorylated mannans . These findings suggest that the transfer step of mannosyl-1-phosphate into the precursor(s) of the wild-type strain mannans during the biosynthetic process corresponds to the key reaction responsible for the anionic heterogeneity due to the density heterogeneity of the antigenic determinants.

Nucleic Acids Res, 1980 Sep 11, 8(17), 3841 - 9
Post-transcriptional modification of the poly(A) length of galactose-1-phosphate uridyl transferase mRNA in Saccharomyces cerevisiae; Saunders CA et al.; Thermal elution poly(U)-Sepharose chromatography was utilized to fractionate yeast mRNA based on poly(A) size . Analysis of the in vitro translation products of the fractionated RNAs in a wheat-embryo cell-free protein synthesis system shows a heterogeneous but equal distribution of these abundant translatable mRNAs in the different poly(A) size classes . By comparing the translational activity of inducible galactose-1-phosphate uridyl transferase mRNA, which can be monitored as a function of age, to contitutive mRNAs, we demonstrate that initially galactose-1-phosphate uridyl transferase mRNA has a uniformly large poly(A) tail which becomes heterogeneous and shorter with age in the cytoplasm . These observations are consistent with the previously observed cytoplasmic poly(A) catabolism in yeast and with cytoplasmic post-transcriptional modification of the poly(A) length of galactose-1-phosphate uridyl transferase mRNA.

J Biol Chem, 1980 Sep 10, 255(17), 8019 - 22
The effect of delta-aminolevulinate on catalase T-messenger RNA levels in delta-aminolevulinate synthase-defective mutants of Saccharomyces cerevisiae; Richter K et al.; Total RNA was isolated from mutants of Saccharomyces cerevisiae that lack active delta-aminolevulinate synthase and are therefore defective in heme biosynthesis . The RNAs were translated in the cell-free protein synthesis system from wheat germ, and the catalase T synthesized was isolated by immunoadsorption and polyacrylamide gel electrophoresis in the presence of dodecyl sulfate . Little or no catalase T product was detected with RNA from mutant cells grown in the absence of a heme precursor . As judged from in vitro translational capacity, RNA fractions from mutant cells grown in the presence of delta-aminolevulinate contained at least 10 times more catalase T mRNA than RNA from unsupplemented cells.

Genetics, 1980 Sep, 96(1), 137 - 46
Mapping of the proteinase b structural gene PRB1, in Saccharomyces cerevisiae and identification of nonsense alleles within the locus; Zubenko GS et al.; We report the mapping of the structural gene for proteinase B, PRB1 . It is located 1.1 cM proximal to CAN1 on the left arm of chromosome V of Saccharomyces cerevisiae . We have identified 34 amber and 12 ochre mutations among the 126 prb1 mutations in our collection.

J Bacteriol, 1980 Sep, 143(3), 1527 - 9
Isolation and properties of an antisuppressor in Saccharomyces cerevisiae specific for an omnipotent suppressor; Liebman SW et al.; A new Mendelian antisuppressor, ASU10, was isolated and shown to reduce the efficiency of the omnipotent yeast suppressor, sup35 . ASU10 had no effect on the other omnipotent suppressor, sup45, or on several amber suppressors.

J Bacteriol, 1980 Sep, 143(3), 1403 - 10
Proline: an essential intermediate in arginine degradation in Saccharomyces cerevisiae; Brandriss MC et al.; Results of studies on proline-nonutilizing (Put-) mutants of the yeast Saccharomyces cerevisiae indicate that proline is an essential intermediate in the degradation of arginine . Put- mutants excreted proline when grown on arginine or ornithine as the sole nitrogen source . Yeast cells contained a single enzyme, delta 1-pyrroline-5-carboxylate (P5C) dehydrogenase, which is essential for the complete degradation of both proline and arginine . The sole inducer of this enzyme was found to be proline . P5C dehydrogenase converted P5C to glutamate, but only when the P5C was derived directly from proline . When the P5C was derived from ornithine, it was first converted to proline by the enzyme P5C reductase . Proline was then converted back to P5C and finally to glutamate by the Put enzymes proline oxidase and P5C dehydrogenase.

J Bacteriol, 1980 Sep, 143(3), 1384 - 94
Reserve carbohydrate metabolism in Saccharomyces cerevisiae: responses to nutrient limitation; Lillie SH et al.; The amounts of glycogen and trehalose have been measured in cells of a prototrophic diploid yeast strain subjected to a variety of nutrient limitations . Both glycogen and trehalose were accumulated in cells deprived specifically of nirogen, sulfur, or phosphorus, suggesting that reserve carbohydrate accumulation is a general response to nutrient limitation . The patterns of accumulation and utilization of glycogen and trehalose were not identical under these conditions, suggesting that the two carbohydrates may play distinct physiological roles . Glycogen and trehalose were also accumulated by cells undergoing carbon and energy limitation, both during diauxic growth in a relatively poor medium and during the approach to stationary phase in a rich medium . Growth in the rich medium was shown to be carbon or energy limited or both, although the interaction between carbon source limitation and oxygen limitation was complex . In both media, the pattern of glycogen accumulation and utilization was compatible with its serving as a source of energy both during respiratory adaptation and during a subsequent starvation . In contrast, the pattern of trehalose accumulation and utilization seemed compatible only with the latter role . In cultures that were depleting their supplies of exogenous glucose, the accumulation of glycogen began at glucose concentrations well above those sufficient to suppress glycogen accumulation in cultures growing with a constant concentration of exogenous glucose . The mechanism of this effect is not clear, but may involve a response to the rapid rate of change in the glucose concentration.

J Bacteriol, 1980 Sep, 143(3), 1179 - 86
Genetic analysis of Saccharomyces cerevisiae transformed by plasmid containing a supressor transfer ribonucleic acid gene; Thomas DY et al.; The behavior in Saccharomyces cerevisiae of plasmid pYTE1, which contains yeast tyrosine-inserting ochre suppressor SUP4.o, a 4-kilobase EcoRI fragment of yeast 2muDNA, and the bacterial plasmid pBR322, has been studied . Selection of yeast transformants was by suppression of multiple ochre mutations . About 10(3) to 10(4) transformants per microgram of pYTE1 dfeoxyribonucleic acid were obtained . The majority of transformants contained both an integrated copy of the SUP4.o gene plus pBR322 deoxyribonucleic acid sequences and autonomously replicating forms of the plasmid . The integrated copy was extremely stable mitotically and meiotically, but the associated nonintegrated copies were lost at meiosis . The chromosomally integrated pBR322 sequences were linked to the SUP4.o gene . The integration site was at the SUP4+ locus . In transformants with only nonintegrated copies of pYTE1, the expression of suppression was reduced, and the plasmid was unstable in mitosis . Plasmid deoxyribonucleic acid preparations from both types of transformant could be used to retransform yeast cells . Plasmid pYTE1 has restriction enzyme sites useful for the high frequency and stable transformation of other genes into yeasts . The potential uses of this plasmid for transformation of other organisms is discussed.

J Bacteriol, 1980 Sep, 143(3), 1530 - 3
Cloning of the URA1 gene of Saccharomyces cerevisiae; Guerry-Kopecko P et al.; A 5.7-kilobase segment of Saccharomyces cerevisiae deoxyribonucleic acid which complements both the yeast ura1 and Escherichia coli pyrD mutations in dihydroorotate dehydrogenase has been cloned in plasmid YRp7.

Carbohydr Res, 1980 Aug 15, 83(2), 363 - 70
Growth-inhibitory activity of the D-mannan of Saccharomyces cerevisiae X2180-1A-5 mutant strain against mouse-implanted sarcoma 180 and Ehrlich-carcinoma solid tumor; Matsumoto T et al.; The D-mannan of Saccharomyces cerevisiae X2180-1A-5 mutant strain, which possesses a main chain composed of alpha-(1 yields 6) linked D-mannopyranosyl residues and a small proportion of branches composed of alpha-(1 yields 2)- and alpha-(1 yields 3)-linked D-mannopyranosyl residues, showed strong growth-inhibitory activity against mouse-implanted Sarcoma 180 and Ehrlich-carcinoma solid tumor . The observation that the level of this activity was nearly identical with that of the D-mannan of a wild-type strain of bakers' yeast, which possesses a high proportion of branches composed of alpha-(1 yields 2)-and alpha-(1 yields 3)-linked D-mannopyranosyl residues, suggests that the branches are not essential for antitumor activity . The partial acid-degradation products of both D-mannans, the molecular weight of which was one-third of that of each parent D-mannan, had only one half of the antitumor activity of the parent D-mannans . This suggests that molecular size is the most important factor for the differences in acitvity of the polysaccharides of wild and mutant strains.

J Bacteriol, 1980 Aug, 143(2), 958 - 65
Properties of polyadenylate-associated ribonucleic acid from Saccharomyces cerevisiae ascospores; Harper JF et al.; Bulk ribonucleic acid (RNA) was isolated from mechanically disrupted ascospores of Saccharomyces cerevisiae . After two passes over an oligo (dT10) cellulose column, the portion which bound, called poly(A)(+), was characterized . It is heterodisperse in size with a mean molecular weight of approximately 4 X 10(5), but contains some species as large as 7 X 10(5) . The base composition is similar to vegetative poly(A)(+) RNA . The polyadenylate segment is also heterogenous in size, ranging from 90 to 20 bases in length, with a peak at approximately 60 nucleotides in length . Pulse-labeling of asci with {3H-methyl}methionine yields two "caps," 7-methyl guanosine-5'-triphosphoryl-5'-adenosine (or guanosine) identical to that found in vegetative poly(A)(+) RNA . The poly(A)(+) RNA in spores is found in polyribosomes which are, on the average, smaller than vegetative ones . Long-term labeling studies indicate that the fraction of poly(A)(+) RNA in spores is similar to that in vegetative cells.

J Bacteriol, 1980 Aug, 143(2), 710 - 4
Levels of acid-soluble polyphosphate in growing cultures of Saccharomyces cerevisiae; Solimene R et al.; Short-chain acid-soluble polyphosphates were extracted from growing cultures of Saccharomyces cerevisiae, and the changes in the levels of these compounds were determined . The production of acid-soluble polyphosphates correlated with the mitochondrial activities since it occurred in two bursts in respiration-competent yeast cells and in only one burst in respiration-deficient yeast cells . The possible role of these compounds is discussed.

J Bacteriol, 1980 Aug, 143(2), 603 - 12
Alterations in translatable ribonucleic acid after heat shock of Saccharomyces cerevisiae; McAlister L et al.; Changes in populations of translatable messenger ribonucleic acids (mRNA's) after heat shock of Saccharomyces cerevisiae were examined and found to correlate very closely with transient alterations in patterns of in vivo protein synthesis . Initial changes included an increase in translatable species coding for polypeptides synthesized during heat shock; this increase was found to be dependent on transcription but did not require ongoing protein synthesis . A decrease was observed in the level of translatable mRNA's coding for polypeptides whose synthesis was repressed after heat shock . This decrease was much more rapid than can be explained solely by termination of transcription . Requirements for this rapid loss of RNA from the translatable pool included both transcription and an active rna1 gene product but not protein synthesis . After the initial changes in translatable RNA induced by heat shock, the patterns of both in vivo and in vitro translation products began to revert to the preshock levels . This recovery period, unlike the earlier changes, was dependent upon a requisite period of protein synthesis.

Genetics, 1980 Aug, 95(4), 855 - 79
Frameshift suppression in Saccharomyces cerevisiae . III . Isolation and genetic properties of group III suppressors; Cummins CM et al.; Suppressors of ICR-induced mutations that exhibit behavior similar to bacterial frameshift suppressors have been identified in the yeast Saccharomyces cerevisiae . The yeast suppressors have been divided into two groups . Previous evidence indicated that suppressors of one group (Group II: SUF1, SUF3, SUF4, SUF5 and SUF6) represent mutations in the structural genes for glycyl-tRNA's . Suppressors of the other group (Group III: SUF2 and SUF7) were less well characterized . Although they suppressed some ICR-revertible mutations, they failed to suppress Group II frameshift mutations . This communication provides a more thorough characterization of the Group III suppressors and describes the isolation and properties of four new suppressors in that group (SUF8, SUF9, SUF10 and suf11).--In our original study, Group III suppressors were isolated as revertants of the Group III mutations his4-712 and his4-713 . All suppressors obtained as ICR-induced revertants of these mutations mapped at the SUF2 locus near the centromere of chromosome III . Suppressors mapping at other loci were obtained in this study by analyzing spontaneous and UV-induced revertants of the Group III mutations . SUF2 and SUF10 suppress both Group III his4 mutations, whereas SUF7, SUF8, SUF9 and suf11 suppress his4-713, but not his4-712 . All of the suppressors except suf11 are dominant in diploids homozygous for his4-713 . The suppressors fail to suppress representative UAA, UAG and UGA nonsense mutations.--SUF9 is linked to the centromere of chromosome VI, and SUF10 is linked to the centromere of chromosome XIV . A triploid mapping procedure was used to determine the chromosome locations of SUF7 and SUF8 . Subsequent standard crosses revealed linkage of SUF7 to cdc5 on chromosome Xiii and linkage of SUF8 to cdc12 and pet3 on chromosome VIII.

Genetics, 1980 Aug, 95(4), 833 - 53
Frameshift suppression Saccharomyces cerevisiae . II . Genetic properties of group II suppressors; Culbertson MR et al.; Suppressors of ICR-induced mutations that exhibit behavior similar to bacterial frameshift suppressors have been identified in the yeast Saccharomyces cerevisiae . The yeast suppressors have been divided into two groups . One of these groups (Group II: SUF1, SUF3, SUF4, SUF5 and SUF6) appears to include a set of informational suppressors in which the vehicle of suppression is glycyl-tRNA . Some of the genetic properties of Group II suppressors are described in this communication.--Corevertants of the Group II frameshift mutations his4-519 and leu2-3 have been characterized to determine the spectrum of reversion events induced by the frameshift mutagen ICR-170 . Seventy-three ICR-induced corevertants were analyzed . With the exception of one cerevertant, which carried an allele of SUF1, all carried alleles of SUF3 or SUF5 . SUF1, SUF3, SUF4 and SUF6 were represented among spontaneous and UV-induced corevertants . In the course of these experiments one of the suppressors was mapped . SUF5, the probable structural gene for tRNAGLY1, is located between ade2 and ade9 on chromosome XV.--SUF1, SUF4 and SUF6 have novel properties and comprise a distinct subset of suppressors . Although these suppressors show no genetic linkage to each other, they share several common features including lethality in haploid pairwise combinations, reduced tRNAGLY3 isoacceptor activity and increased efficiency of suppression in strains carrying the cytoplasmically inherited {PSI} element . In addition, strains carrying SUF1, SUF4 or SUF6 are phenotypically unstable and give rise to mitotic Suf+ segments at high frequency . These segregants invariably contain a linked, second-site mutation that maps in or adjacent to the suppressor gene itself . Strains carrying any of these suppressors also give rise to mitotic segregants that exhibit enhanced efficiency of suppression; mutations responsible for this phenotype map at two loci, upf1 and upf2 . These genes show no genetic linkage to any of the group II suppressors.--Methods that permit positive selection have been devised in order to examine large numbers of variants . The importance of these interacting mutants is underscored by their potential utility in studying suppressor function at the molecular level.

Mutat Res, 1980 Aug, 72(3), 397 - 404
Hycanthone as a specific frameshift mutagen in Saccharomyces cerevisiae; Lucchini G et al.; Reversion of mutations of different molecular nature was studied after treatment with hycanthone in mild conditions (0.05--0.4 mM, 4 h in the dark, pH 7.2) . The mutagen had a very low reversion activity on 3 missense and 4 nonsense mutations (2 UAA and 2 UAG), although it was very active on 3 frameshift mutations . Our data on intragenic reversion and frameshift suppressors indicate that hycanthone can induce both insertions and deletions.

Biochem J, 1980 Jul 15, 190(1), 145 - 56
Regulation of mitochondrial biogenesis . Occurrence of non-functioning components of the mitochondrial respiratory chain in Saccharomyces cerevisiae grown in the presence of proteinase inhibitors: evidence for proteolytic control over assembly of the respiratory chain; Galkin AV et al.; Yeast was grown in glucose- or galactose-containing media without or with proteinase inhibitors, phenylmethanesulphonyl fluoride and pepstatin . Culture growth was practically not affected by these compounds . Yeast growth on glucose in the presence of either phenylmethanesulphonyl fluoride or pepstatin entails accumulation of cytochromes c, c1, b and aa3 to a 25--30% excess above the control by the stationary phase, while cell respiration is unaffected . During growth on galactose the maximal cytochrome content (per unit weight of biomass) is reached in the mid-exponential phase and then decreases by 30--40% towards the stationary phase, while cell respiration remains constant . Addition of phenylmethanesulphonyl fluoride or pepstatin in the mid-exponential phase blocks the decrease in cytochrome levels and has no effect on cell respiration . Mitochondrial populations isolated from stationary-phase control and phenylmethanesulphonyl fluoride-grown cells glucose cultures display identical succinate oxidase and partial-respiratory-chain activities, despite the differences in cytochrome contents . However, the activities of individual respiratory complexes measured after maximal activation are nearly proportional to the amounts of corresponding components . The same situation holds true for mitochondrial populations from mid-exponential-phase, stationary-phase control and stationary-phase inhibitor-grown cells of galactose cultures . The findings suggest that the 'surplus' respiratory-chain components do not participate in electron flow because of the lack of interaction with adjacent carriers.

Prikl Biokhim Mikrobiol, 1980 Jul-Aug, 16(4), 528 - 37
{Purification and characterization of beta-fructofuranosidase from yeast Saccharomyces cerevisiae}; Matulaitite EIu et al.; Intracellular invertase was isolated from the yeast Saccharomyces cerevisiae, race XI, and purified by ion-exchange chromatography on DEAE-cellulose and gel-filtration on Sephadex G-200 . The effect of pH, temperature, metal ions, thiolic agents, and EDTA on the enzyme activity and stability was investigated . The enzyme was estimated to have a molecular weight of 270 000 and a carbohydrate content of 20--30% . By disc-electrophoresis and isoelectric focusing the highly purified enzyme was found to be heterogenous . Its molecular forms had isoelectric points at 3.0, 4.0, 4.5, and 4.9.

Genetics, 1980 Jul, 95(3), 611 - 30
Ultraviolet mutagenesis studies of {psi}, a cytoplasmic determinant of Saccharomyces cerevisiae; Tuite MF et al.; UV mutagenesis was used to probe the molecular nature of {psi}, a nonmitochondrial cytoplasmic determinant of Saccharomyces cerevisiae involved in the control of nonsense suppression . The UV-induced mutation from {psi+} to {psi-} showed characteristics of forward nuclear gene mutation in terms of frequency, induction kinetics, occurrence of whole and sectored mutant clones and the effect of the stage in the growth cycle on mutation frequency . The involvement of pyrimidine dimers in the premutational lesion giving the {psi-} mutation was demonstrated by photoreactivation . UV-induced damage to the {psi} genetic determinant was shown to be repaired by nuclear-coded repair enzymes that are responsible for the repair of nuclear DNA damage . UV-induced damage to mitochondrial DNA appeared to be, at least partly, under the control of different repair processes . The evidence obtained suggests that the {psi} determinant is DNA.

Proc Natl Acad Sci U S A, 1980 Jul, 77(7), 3912 - 6
Isolation and sequence of the gene for actin in Saccharomyces cerevisiae; Ng R et al.; The yeast Saccharomyces cerevisiae is known to contain the highly conserved and unbiquitous protein actin . We have used cloned actin sequences from Dictyostelium discoideum to identify and clone the actin gene in yeast . Hybridization to genomic fragments of yeast DNA suggest that there is a single actin gene in yeast . We have determined the nucleotide sequence of that gene and its flanking regions . The sequence of the gene reveals an intervening sequence of 309 base pairs in the coding sequences at the 5' end of the gene . The existence and location of the intervening sequence was verified by using the dideoxy chain termination technique to determine the sequence at the 5' terminus of the actin mRNA . The similarity of the splice junction sequences in this gene to those found in higher eukaryotes suggests that yeast must possess a similar splicing enzyme.

Mutat Res, 1980 Jul, 78(3), 243 - 52
Induction of mitotic recombination by certain hair-dye chemicals in Saccharomyces cerevisiae; Mayer VW et al.; A number of procedures were used to test for the potential of 5 hair-dye chemicals, 4-nitro-o-phenylenediamine, 2-nitro-p-phenylenediamine, m-phenylenediamine 2,4-diaminoanisole sulfate and 2,5-diaminoanisole sulfate, to induce genetic damage in yeast strains D3 and D4 of Saccharomyces cerevisiae . Various plate-test procedures, short-term suspension assays in phosphate buffer and suspension assays with liver enzyme activation all proved to be ineffective for demonstrating genetic effects of these chemicals . Only suspension assays in which the yeast cells were treated with the test chemical under growing conditions for up to 72 h were effective in demonstrating the genetic activity of 4-nitro-o-phenylenediamine and 2,4-diaminoanisole sulfate . The implications of these results for testing of mutagens in yeast systems are discussed along with other supportive evidence from the literature.

Eur J Biochem, 1980 Jul, 108(2), 439 - 47
Regulation of compartmentation of amino acid pools in Saccharomyces cerevisiae and its effects on metabolic control; Messenguy F et al.; Compartmentation of intracellular amino acid pools has been studied under various growth conditions in wild-type strains as well as in mutants . Aspartate, glutamate, leucine and isoleucine pools are present in high concentrations in the cytoplasm, while all the other amino acids are more vacuolar . The nature of the nitrogen source for growth, the effectiveness of nitrogen assimilation, the rate of protein synthesis and the presence of high internal basic amino acid pools are important factors in the repartition of amino acid pools between the cytoplasm and the vacuole.

J Bacteriol, 1980 Jul, 143(1), 422 - 6
Nitrogen catabolite repression of asparaginase II in Saccharomyces cerevisiae; Dunlop PC et al.; The biosynthesis of asparaginase II in Saccharomyces cerevisiae is subject to strong catabolite repression by a variety of nitrogen compounds . In the present study, asparaginase II synthesis was examined in a wild-type yeast strain and in strains carrying gdhA, gdhCR, or gdhCS mutations . The following effects were observed: (i) In the wild-type strain, the biosynthesis of asparaginase II was strongly repressed when either 10 mM ammonium sulfate or various amino acids (10 mM) served as the source of nitrogen . (ii) In a yeast strain carrying the gdhA mutation, asparaginase II was synthesized at fully derepressed levels when 10 mM ammonium sulfate was the source of nitrogen . When amino acids (10 mM) served as the nitrogen source, asparaginase II synthesis was strongly repressed . (iii) In a strain carrying the gdhCR mutation, the synthesis of asparaginase II was partially (30 to 40%) derepressed when either 10 mM ammonium sulfate or amino acids were present in the medium . (iv) In a yeast strain containing both gdhA and gdhCR mutations, asparaginase II synthesis was fully derepressed when 10 mM ammonium sulfate was the nitrogen source and partially derepressed when 10 mM amino acids were present . (v) Yeast strains carrying the gdhCS mutation were indistinguishable from the wild-type strain with respect to asparaginase II synthesis.

Mutat Res, 1980 Jul, 71(2), 193 - 9
Induction of rho- mutations in yeast Saccharomyces cerevisiae by ethanol; Bandas EL et al.; The kinetics of the killing effect of ethanol was studied at 6-30% concentrations . Ploidy of cells, deficiency of the excision-repair system or holding under no-growth conditions did not influence survival . Ethanol at 24% increased, in the wild strain, the number of respiration-deficient cells from a spontaneous level of 0.4% up to nearly half of all survivors . Genetic analysis showed the mitochondrial nature of induced respiration-deficient mutants (or rho-) . The influence of yeast resistance to some antibiotics was studied on rho- mutagenesis, both spontaneous and induced by ethanol . Neomycin-resistant strains were characterized by a significantly lower level of these mutations than were neomycin-sensitive strains.

Cancer Res, 1980 Jul, 40(7), 2323 - 9
Effect of tumor promoters on ultraviolet light-induced mutation and mitotic recombination in Saccharomyces cerevisiae; Kunz BA et al.; Recently, it has been suggested that mitotic recombination is involved in tumor promotion . On this basis, one might expect tumor promoters to be recombinagenic . D7 is a diploid strain of yeast in which both mutation and mitotic recombination can be measured . We have used this strain to assay the known tumor promoters, iodoacetate, anthralin, and 12-O-tetradecanoylphorbol-13-acetate, and the cocarcinogen, catechol, for mutagenicity, recombinagenicity, and the ability to enhance ultraviolet light (UV)-induced genetic events . In the absence of preirradiation with UV, iodoacetate was found to be recombinagenic whereas catechol was mutagenic; however, in both cases, the effects were small . Iodoacetate, anthralin, and catechol potentiated UV-induced mitotic crossing-over, aberrant colony formation, and mutation, while catechol also increased UV-induced gene conversion . We were unable to detect any mutagenic or recombinagenic effect of 12-O-tetradecanoyl-phorbol-13-acetate in either whole cells or spheroplasts . Our results do not indicate any consistent correlation between tumor-promoting activity and the ability of an agent to induce mitotic recombination in yeast . However, the ability to potentiate UV-induced mutation and mitotic recombination may reflect the cocarcinogenic activity of certain promoters.

Eur J Biochem, 1980 Jul, 108(2), 373 - 7
Two asparagine synthetases in Saccharomyces cerevisiae; Ramos F et al.; In Saccharomyces cerevisiae L-asparagine auxotrophy, resulting from a lack of L-asparagine synthesis, needs simultaneous defects in two genes . This unusual situation is shown to result from the occurrence of two L-asparagine synthetases . The meaning of this duplication remains obscure . The properties of the two enzymes are remarkably similar: both have a molecular weight of 150,000 and they exhibit a slight repression and a similar inhibition by asparagine . Neither one is located in mitochondria and both are probably cytosolic . Their identification so far lies only in their behaviour on ion-exchange chromatography and in the encoding genes.

Nucleic Acids Res, 1980 Jun 25, 8(12), 2679 - 89
The 5' terminus of the precursor ribosomal RNA of Saccharomyces cerevisiae; Klemenz R et al.; The 5' terminus of Saccharomyces cereviasiae 35S pre rRNA was mapped on the rDNA using two methods: 1) Suitable restriction endonuclease fragments were hybridized to total high molecular weight RNA and extended with reverse transcriptase to the 5' end of the RNA template . 2) Other restriction fragments spanning the 5' terminus of 35S pre rRNA and radioactively labeled at their ends were hybridized to high molecular weight RNA and the non hybridized nucleic acids were digested with S1 nuclease . On the basis of these experiments, the 5' terminus of 35S pre rRNA was placed approximately 670 nucleotides upstream from the 17S rRNA coding region . The exact position was determined by reverse transcription as above, but in the presence of dideoxyribonucleoside triphosphates, which served as a way of sequencing the 5' terminal region . 35S pre rRNA synthesis is initiated at a site in EcoRI restriction fragment B which is 48 nucleotides upstream from the EcoRI cleavage site in the coding strand.

Nucleic Acids Res, 1980 Jun 11, 8(11), 2349 - 63
Virion DNA-independent RNA polymerase from Saccharomyces cerevisiae; Welsh JD et al.; The "killer" plasmid and a larger double-stranded RNA plasmid of yeast exist in intracellular virion particles . Purification of these particles from a diploid killer strain of yeast (grown into stationary growth on ethanol) resulted in co-purification of a DNA-independent RNA polymerase activity . This activity incorporates and requires all four ribonucleoside triphosphates and will not act on deoxyribonucleoside triphosphates . The reaction requires magnesium, is inhibited by sulfhydryl-oxidizing reagents and high concentrations of monovalent cation, but is insensitive to DNase, alpha-amanitin, and actinomycin D . Pyrophosphate inhibits the reaction as does ethidium bromide . Exogenous nucleic acids have no effect on the reaction . The product is mostly single-stranded RNA, some of which is released from the enzymatically active virions.

Genetics, 1980 Jun, 95(2), 273 - 88
Isolation and characterization of pso mutants sensitive to photo-addition of psoralen derivatives in Saccharomyces cerevisiae; Henriques JA et al.; We have isolated mutants sensitive to photo-addition of bi-functional and mono-functional derivatives of psoralen in Saccharomyces cerevisiae . Three of these pso mutants were analyzed in detail . They segregate in meiosis like Mendelian genes and complement each other, as well as existing radiation-sensitive (rad and rev) mutants . The study of heterozygous diploid strains (PSO+/pso) indicates that the three pso genes are recessive . The mutant pso1--1 demonstrates a cross-sensitivity to UV and gamma-rays, whereas mutants pso2--1 and pso3--1 are specifically sensitive to photo-addition of psoralen derivatives . The comparison of exponentially growing cells to stationary-phase cells demonstrates that for the three mutants the defect in repair capacity of DNA cross-links and monoadducts concerns G1 and early S-phase cells . The pso2--1 mutant is, however, also defective in G2 repair and loses diploid resistance when it is in the homozygous state.--The block in repair capacity in these novel mutants is discussed in relation to the three other repair pathways known to be involved in the repair of furocoumarins photo-induced lesions in yeast DNA.

Mutat Res, 1980 Jun, 78(2), 151 - 7
Petite induction in Saccharomyces cerevisiae by ethidium analogs: distinction between resting and growing cells; Fukunaga M et al.; The importance of specific substituents, especially amino azide groups, for ethidium induction of petites was evaluated in resting and dividing cells of Saccharomyces cerevisiae through the study of a series of ethidium analogs . The structural requirements in resting and growing cells were found to be different, suggesting that at least two mechanisms are responsible for induction . The significance of particular substituents in the induction processes were recognized by: (1) a dependence upon the ethyl substituent at the ring nitrogen in both actively growing and in resting cells; and (2) the implication that amino substituents are important for the effect in dividing cells and especially in resting cells . Photolytic enhancement of petite induction (via a nitrene which forms a covalent linkage to a biological site) was observed for 3 of the azide analogs, which emphasizes the likelihood that metabolic activation of ethidium to a covalent complex is responsible for its effectiveness . Furthermore, these studies indicate that these monoazide analogs should be ideal probes for examining the mitochondrial mutagenic processes.

J Cell Biol, 1980 Jun, 85(3), 811 - 22
Mutants of Saccharomyces cerevisiae unresponsive to cell division control by polypeptide mating hormone; Hartwell LH; Temperature-sensitive mutations that produce insensitivity to division arrest by alpha-factor, a mating pheromone, were isolated in an MATa strain of Saccharomyces cerevisiae and shown by complementation studies to difine eight genes . All of these mutations (designated ste) produce sterility at the restrictive temperature in MATa cells, and mutations in seven of the genes produce sterility in MAT alpha cells . In no case was the sterility associated with these mutations coorectible by including wild-type cells of the same mating type in the mating test nor did nay of the mutants inhibit mating of the wild-type cells; the defect appears to be intrinsic to the cell for mutations in each of the genes . Apparently, none of the mutants is defective exclusively in division arrest by alpha-factor, as the sterility of none is suppressed by a temperature-sensitive cdc 28 mutation (the latter imposes division arrest at the correct cell cycle stage for mating) . The mutants were examined for features that are inducible in MATa cells by alpha-factor (agglutinin synthesis as well as division arrest) and for the characteristics that constitutively distinguish MATa from MAT alpha cells (a-factor production, alpha-factor destruction) . ste2 Mutants are defective specifically in the two inducible properties, whereas ste4, 5, 7, 8, 9, 11, and 12 mutants are defective, to varying degrees, in constitutive as well as inducible aspects . Mutations in ste8 and 9 assume a polar budding pattern unlike either MATa or MAT alpha cells but characteristic of MATa/alpha cells . This study defines seven genes that function in two cell types (MATa and alpha) to control the differentiation of cell type and one gene, ste2, that functions exclusively in MATa cells to mediate responsiveness to polypeptide hormone.

J Bacteriol, 1980 Jun, 142(3), 808 - 18
Asymmetrical division of Saccharomyces cerevisiae; Lord PG et al.; The unequal division model proposed for budding yeast (L . H . Hartwell and M . W . Unger, J . Cell Biol . 75:422-435, 1977) was tested by bud scar analyses of steady-state exponential batch cultures of Saccharomyces cerevisiae growing at 30 degrees C at 19 different rates, which were obtained by altering the carbon source . The analyses involved counting the number of bud scars, determining the presence or absence of buds on at least 1,000 cells, and independently measuring the doubling times (gamma) by cell number increase . A number of assumptions in the model were tested and found to be in good agreement with the model . Maximum likelihood estimates of daughter cycle time (D), parent cycle time (P), and the budded phase (B) were obtained, and we concluded that asymmetrical division occurred at all growth rates tested (gamma, 75 to 250 min) . D, P, and B are all linearly related to gamma, and D, P, and gamma converge to equality (symmetrical division) at gamma = 65 min . Expressions for the genealogical age distribution for asymmetrically dividing yeast cells were derived . The fraction of daughter cells in steady-state populations is e-alpha P, and the fraction of parent cells of age n (where n is the number of buds that a cell has produced) is (e-alpha P)n-1(1-e-alpha P)2, where alpha = IN2/gamma; thus, the distribution changes with growth rate . The frequency of cells with different numbers of bud scars (i.e., different genealogical ages) was determined for all growth rates, and the observed distribution changed with the growth rate in the manner predicted . In this haploid strain new buds formed adjacent to the previous buds in a regular pattern, but at slower growth rates the pattern was more irregular . The median volume of the cells and the volume at start in the cell cycle both increased at faster growth rates . The implications of these findings for the control of the cell cycle are discussed.

J Bacteriol, 1980 Jun, 142(3), 791 - 9
Regulatory mutations affecting ornithine decarboxylase activity in Saccharomyces cerevisiae; Cohn MS et al.; We isolated several strains of Saccharomyces cerevisiae containing mutations mapping at a single chromosomal gene (spe10); these strains are defective in the decarboxylation of L-ornithine to form putrescine and consequently do not synthesize spermidine and spermine . The growth of one of these mutants was completely eliminated in a polyamine-deficient medium; the growth rate was restored to normal if putrescine, spermidine, or spermine was added . spe10 is not linked to spe2 (adenosylmethionine decarboxylase) or spe3 (putrescine aminopropyltransferase {spermidine synthease}) . spe 10 is probably a regulatory gene rather than the structural gene for ornithine decarboxylase, since we isolated two different mutations which bypassed spe10 mutants; these were spe4, an unliked recessive mutation, and spe40, a dominant mutation linked to spe10 . Both spe4 and spe40 mutants exhibited a deficiency of spermidine aminopropyltransferase (spermine synthase), but not of putrescine aminopropyltransferase . This suggests that ornithine decarboxylase activity is negatively controlled by the presence of spermidine aminopropyltransferase.

J Bacteriol, 1980 Jun, 142(3), 747 - 54
Biosynthesis of phosphoinositol-containing sphingolipids from phosphatidylinositol by a membrane preparation from Saccharomyces cerevisiae; Becker GW et al.; Incubation of membranes prepared from Saccharomyces cerevisiae with {32P}phosphatidyl{3H}inositol resulted in the transfer of both labels to two products which were characterized as two species of inositolphosphoceramide, differing in the ceramide portion of the molecule . The products were characterized on the basis of stability in mild alkali, mobility on silica gel-impregnated paper, chromatography on silicic acid columns, and release of inositol phosphate upon base hydrolysis . The reaction did not require the addition of metals, nor was it inhibited by ethylenediaminetetraacetic acid . The detergents Triton X-100 and Tween 20 provided little, if any, stimulation . At relatively high concentrations of phosphatidylinositol (1 to 4 mM), the in vitro rate was about 20% of the in vivo rate . Although ceramide was a logical substrate, the reaction could not be greatly stimulated by the addition of ceramides containing mono- and dihydroxy fatty acids . In addition, incubation of yeast membranes with {32P}phosphatidylinositol gave rise to a product that was chromatographically indistinguishable from the major yeast phosphosphingolipid, mannose-(inositol-P)2 ceramide.

J Bacteriol, 1980 Jun, 142(3), 852 - 8
Inhibition and activation of mannan synthesis in Saccharomyces cerevisiae spheroplast lysates; Harrington CR et al.; Mannan synthetase activity in spheroplast lysates prepared from Saccharomyces cerevisiae was measured by following the incorporation of {14C}mannose from guanosine 5'-diphosphate-{14C}mannose into material precipitable with cold 0.3 M perchloric acid . When enzyme activity was assayed at high concentrations of spheroplast lysate protein (10 mg/ml) in the presence of 7.5 mM MnCl2, a severe inhibition was observed . This inhibition could be relieved by preincubation of the spheroplast lysate at 4 degrees C for 16 to 32 h before assay, by repeated freezing and thawing of the spheroplast lysate, or by the omission of MnCl2 from assay mixtures . The addition of ethylenediaminetetraacetic acid or monovalent cations removed inhibition in the presence of Mn2+ . No similar inhibition was observed when a washed membrane fraction was substituted for spheroplast lysate as the source of mannan synthetase . The supernatant fluid obtained by centrifuging spheroplast lysate at 100,000 x g, when added to assay mixtures containing either spheroplast lysate preincubated at 4 degrees C or washed membrane fraction, also caused inhibition of enzyme activity . This inhibition required 7.5 mM MnCl2 and was destroyed by heating the supernatant fluid at 60 degrees C for 10 min, or by trypsin treatment at 30 degrees C . These results indicate the existence of a protein inhibitor of mannan synthesis whose inhibitory activity in spheroplast lysates may be modulated by preincubation at low temperature or by varying the available Mn2+ concentration.

Biochem J, 1980 Jun 1, 187(3), 843 - 9
Mechanistic studies of carboxypeptidase Y from Saccharomyces cerevisiae . pH and pD profiles and inactivation at low pH (pD) values; Chang WT et al.; Steady-state kinetics of carboxypeptidase Y, a proteinase from yeast, were studied by using the reaction of 4-nitrophenyl trimethylacetate as a probe . The pH profile of kcat . is sigmoidal in H2O-based buffers for the carboxypeptidase Y-catalysed hydrolysis of this ester (kcat . referring to the rate of deacylation of trimethylacetyl-carboxypeptidase Y) . The corresponding pD profile in 2H2O is doubly sigmoidal, with inflexions at pD approximately 3.8 and approximately 6.8 . The ionization of pKDapp . approximately 3.8 is caused by a rapid inactivation in 2H2O media by a process that is only slowly reversed on transfer to pH 7.00 phosphate buffer in H2O . The corresponding inactivation in H2O-based buffers of low pH is considerably slower (approximately 30-fold), follows a first-order rate-dependence and is very strongly pH-dependent, indicating some form of co-operative change in enzyme tertiary structure.

Biochim Biophys Acta, 1980 May 22, 629(3), 445 - 54
Metabolic relationship between invertase and acid phosphatase isoenzymes in Saccharomyces cerevisiae; Rodriguez L et al.; Repressed cells of Saccharomyces cerevisiae, subjected to inhibition of both RNA and protein synthesis, showed a pattern of membrane-bound and cytosol acid phosphatase to the external enzyme which seemed to be linked through a precursor-product relationship . Gel exclusion chromatography did not indicate clear differences between the isoenzymes . Moreover, centrifugation experiments in CsCl and precipitation with concanavalin A suggested that there were no acid phosphatase molecules devoid of carbohydrate . Membrane-bound invertase displayed a molecular weight and a carbohydrate to protein ratio smaller than those of the exocellular enzyme . The values of molecular weight and buoyant density of the membrane-bound enzyme were closer to those found for the cytosol invertase . The stability of the level of the soluble invertase detected in the cytoplasm under derepression conditions, or after RNA or protein synthesis inhibition was found to be only apparent and represented the result of an equilibrium between synthesis and degradation.

Biochemistry, 1980 May 13, 19(10), 2236 - 40
High mobility group proteins of Saccharomyces cerevisiae; Weber S et al.; The yeast Saccharomyces cerevisiae contains four proteins having amino acid compositions typical of the high mobility group (HMG) proteins . Three of these are eluted from chromatin by 0.35 M NaCl; one is not, but it is eluted by 0.25 N HCl . It follows that HMGs cannot, in general, be defined by extractability criteria . Gel mobilities and amino acid compositions indicate that yeast and animal HMGs have diverged markedly.

Proc Natl Acad Sci U S A, 1980 May, 77(5), 2546 - 50
Structure of a split yeast gene: complete nucleotide sequence of the actin gene in Saccharomyces cerevisiae; Gallwitz D et al.; The complete nucleotide sequence of the actin gene from Saccharomyces cerevisiae has been determined . The coding region is interrupted by a 304-base-pair intervening sequence that is located within the triplet coding for amino acid 4 . DNA sequences of the intron-exon junctions are similar to those found in higher eukaryotes and can be aligned such that the intron starts with the dinucleotide 5'-G-T-3' and ends with 5'-A-G-3' . Regions fo homology within the sequences upstream from the initiation codon and those following the termination codon have been detected between the yeast iso-1-cytochrome c gene and the actin gene . As deduced from the nucleotide sequence, yeast actin has 374 amino acid residues . Its primary structure, especially the NH2-terminal third of the protein, is highly conserved during evolution.

Eur J Biochem, 1980 May, 106(2), 661 - 5
Binding and inhibitory effect of 2-heptyl-4-hydroxyquinoline-N-oxide in the presence of ubiquinone-3 in Saccharomyces cerevisiae; Burger G; 1 . 2-Heptyl-4-hydroxyquinoline-N-oxide (HpHOQnO) binds to oxidized mitochondria of Saccharomyces cerevisiae with a dissociation constant of 5 x 10(-8) M and with a ratio of 1 mol per mol cytochrome b . 2 . After addition of 171 micro M ubiquinone-3 to oxidized mitochondria, 0.3 mol HpHOQnO bind to 1 mol cytochrome b . The binding strength of the inhibitor is not essentially affected . 3 . Reduction of mitochondria with succinate results in a strong decrease of the HpHOQnO binding . The dissociation constant could not be calculated on the basis of the applied method . 4 . On the basis of the inhibitory effect of HpHOQnO on reduced mitochondria, a dissociation constant of 5 x 10(-6) M is calculated . 5 . The respiratory electron flow to oxygen is about 100 times as sensitive to HpHOQnO as the electron flow to cytochrome c . 6 . Ubiquinone-3 reverses the inhibition by HpHOQnO and stimulates the electron flow . 7 . The different influence of ubiquinone-3 in binding and in inhibition experiments is discussed as a result of redox conditions.

Cell, 1980 May, 20(1), 199 - 206
Mosaic organization of a mitochondrial gene: evidence from double mutants in the cytochrome b region of Saccharomyces cerevisiae; Alexander NJ et al.; The region coding for apocytochrome b in the mitochondrial genome of Saccharomyces cerevisiae is believed to exhibit a mosaic organization, consisting in certain strains of five exons and four introns . This model can be tested by the use of double mutants, each containing two physically, genetically and phenotypically defined mit- lesions in cis, (that is, in the same mitochondrial chromosome) . Such mutants have been constructed, and the phenotypes of several examples of each of the four possible classes--exon-exon, exon-intron (downstream), intron (upstream)-exon and intron-intron--have been examined . Our results have shown that upstream mutations are always epistatic to downstream ones for polypeptide products, and that regulation of expression of cytochrome oxidase subunit I by introns is epistatic regardless of position . These findings have provided an independent verification of the mosaic model, and also suggest that at least the majority of novel polypeptides accumulating in intron mutants are hybrid products that contain sequences of the wild-type polypeptide.

Experientia, 1980 Apr 15, 36(4), 385 - 6
Active transport of dimethialium in Saccharomyces cerevisiae; Iwashima A et al.; Dimethialium, a derivative of thiamine which has a methyl group in place of hydroxyethyl group at the t-position of the thiazole moiety, was found to be accumulated in nonproliferating cells of Saccharomyces cerevisiae by the same transport mechanism for thiamine . The results strongly support the supposition that thiamine as well as dimethialium can be transported and accumulated without obligatory phosphorylation in yeast cells, since dimethialium is not phosphorylated by yeast thiamine pyrophosphokinase.

J Biol Chem, 1980 Apr 10, 255(7), 3080 - 5
Purification and characterization of a Saccharomyces cerevisiae exoribonuclease which yields 5'-mononucleotides by a 5' leads to 3' mode of hydrolysis; Stevens A; An exoribonuclease producing 5'-mononucleotides has been purified from ribosomes of Saccharomyces cerevisiae . The enzyme has a broad pH optimum around 8.0, requires divalent cation, and is stimulated by monovalent cation with the cation and degree of stimulation being dependent on the substrate used . With either poly(A) or rRNA as substrate, the enzyme has a processive mode of hydrolysis . The oligonucleotides, (pA)3-5, are hydrolyzed by the enzyme, and the hydrolysis is dependent on a 5'-phosphate end group . Phosphorylation of the 3' end has little effect on the rate of hydrolysis . With {3H}poly(A) or {3H}rRNA, labeled differentially at the 5' termini, a more rapid release of 5'-terminal label can be shown, providing evidence that the enzyme hydrolyzes in a 5' leads to 3' direction . Further evidence for a 5' leads to 3' mode of hydrolysis is provided by a study of the products of the hydrolysis of {3H}(pA)5 labeled at the 5' termini with 32P . No 32P label is found in (pA)2 which accumulates as an intermediate.

Nature, 1980 Apr 3, 284(5755), 426 - 30
Unequal crossing over in the ribosomal DNA of Saccharomyces cerevisiae; Szostak JW et al.; Unequal sister chromatid exchanges occur at the ribosomal DNA locus of yeast during mitotic growth . The frequency of unequal crossing over, as measured by the deletion or duplication of an inserted genetic marker (LEU2), is sufficient to maintain the sequence homogeneity of the rDNA repeat units.

Mol Gen Genet, 1980 Apr, 178(1), 69 - 76
The metabolic properties of acid soluble polyphosphates in Saccharomyces cerevisiae; Lusby EW Jr et al.; Tripolyphosphate was found to be the predominant species of soluble polyphosphate in yeast . Evidence is presented which shows that under normal growth conditions tripolyphosphate had little or no turnover . The amounts of the various polyphosphates decreased as the chain length increased . Tetrapolyphosphate was shown to be synthesized more rapidly than tripolyphosphate . These observations suggest that short chain polyphosphates arise by degradation of longer chain length polyphosphates with tripolyphosphate the ultimate degradation product . During nitrogen starvation, the normal accumulation of tripolyphosphate rapidly ceased even though the cells continued normal growth for at least two hours . After the addition of L-amino acids or (NH4)2SO4 to nitrogen starved cells, there was a dramatic increase in the accumulation of tripolyphosphate and tetrapolyphosphate which occurred at the same time as the increase in growth rate . Implications of this result are discussed in terms of possible functions of polyphosphate.

J Bacteriol, 1980 Apr, 142(1), 79 - 89
Effects of inositol starvation on phospholipid and glycan syntheses in Saccharomyces cerevisiae; Hanson BA et al.; The early biochemical consequences of inositol starvation in an inositol auxotroph of Saccharomyces cerevisiae were examined as a means of determining the cellular role of inositol . Upon withdrawal of inositol, the rate of incorporation of 32P-labeled inorganic phosphate into phosphatidylinositol and into the phosphoinositol-containing sphingolipids immediately dropped by 80 and 50%, respectively; however, synthesis of the other major phospholipids continued for 2 to 3 h at control rates . The incorporation of {U-14C}glucose into cell wall glycans began to decline immediately poststarvation and decreased to 50% of the initial rate by 80 min for mannan and by 140 min for alkali- and acid-insoluble glucan . These changes in the rates of synthesis of cell wall glycan and phosphatidylinositol were the earliest effects of inositol starvation, preceding inhibition of the synthesis of protein and ribonucleic acid as measured by incorporation of radioactive precursors into trichloroacetic acid-insoluble cell material . These results suggest that phosphatidylinositol may play a direct role in the synthesis or secretion of yeast glycans.

J Cell Biol, 1980 Apr, 85(1), 96 - 107
Cell cycle phase expansion in nitrogen-limited cultures of Saccharomyces cerevisiae; Rivin CJ et al.; The time and coordination of cell cycle events were examined in the budding yeast Saccharomyces cerevisiae . Whole-cell autoradiographic techniques and time-lapse photography were used to measure the duration of the S, G1, and G2 phases, and the cell cycle positions of "start" and bud emergence, in cells whose growth rates were determined by the source of nitrogen . It was observed that the G1, S, and G2 phases underwent a proportional expansion with increasing cell cycle length, with the S phase occupying the middle half of the cell cycle . In each growth condition, start appeared to correspond to the G1 phase/S phase boundary . Bud emergence did not occur until mid S phase . These results show that the rate of transit through all phases of the cell cycle can vary considerably when cell cycle length changes . When cells growing at different rates were arrested in G1, the following synchronous S phase were of the duration expected from the length of S in each asynchronous population . Cells transferred from a poor nitrogen source to a good one after arrest in G1 went through the subsequent S phase at a rate characteristic of the better medium, indicating that cells are not committed in G1 to an S phase of a particular duration.

J Cell Biol, 1980 Apr, 85(1), 108 - 15
Replication fork rate and origin activation during the S phase of Saccharomyces cerevisiae; Rivin CJ et al.; When the growth rate of the yeast Saccharomyces cerevisiae is limited with various nitrogen sources, the duration of the S phase is proportional to cell cycle length over a fourfold range of growth rates (C.J . Rivin and W . L . Fangman, 1980, J . Cell Biol . 85:96-107) . Molecular parameters of the S phases of these cells were examined by DNA fiber autoradiography . Changes in replication fork rate account completely for the changes in S-phase duration . No changes in origin-to-origin distances were detected . In addition, it was found that while most adjacent replication origins are activated within a few minutes of each other, new activations occur throughout the S phase.

Genetics, 1980 Apr, 94(4), 859 - 70
Duplicated genes producing transposable controlling elements for the mating-type differentiation in Saccharomyces cerevisiae; Oshima T et al.; Mutation of the two homothallic genes, HML alpha/HMLa and HMRa/HMR alpha, in homothallic strains of Saccharomyces cerevisiae was studied . Of 11 mutants of the HML alpha gene, eight were due to a phenotypic mutation from HML alpha to HMLa, i.e., a mutation causing a change in function of the original HML allele to that of the other HML allele (functional mutation), and three were due to a defective mutation at the HML alpha gene, i.e., a mutation causing a nonfunctional allele (nonfunctional mutation) . All 14 mutants of the HMRa gene, on the other hand, were due to a phenotypic mutation from HMRa to HMR alpha i.e., a functional mutation . Phenotypic reverse mutations, i.e., HMLa to HML alpha and HMR alpha to HMRa, were also observed in the cultivation of EMS (ethyl methanesulfonate) treated spores having the HO HMR alpha HMLa genotype . Mutation from heterothallic cells to homothallism was observed in a nonfunctional mutant of the HML alpha gene, by mutagenesis with EMS, but not in the functional mutants of the HML alpha and HMRa genes or in the authentic strains having the alpha HO HMR alpha HML alpha (alpha Hp) and a HO HMRa HMLa (a Hq) genotypes . These observations suggest that the functional mutation is not caused by the direct mutation from a homothallic allele to the opposite, but by replacement of a transposable genic element produced from a homothallic locus with a region of a different homothallic locus . These observations also support the controlling-element model and the cassette model, which have been proposed to explain the mating-type differentiation by the homothallic genes.

J Bacteriol, 1980 Apr, 142(1), 322 - 4
Ultraviolet-endonuclease activity in cell extracts of Saccharomyces cerevisiae mutants defective in excision of pyrimidine dimers; Bekker ML et al.; Cell-free extracts of ultraviolet-sensitive mutants of Saccharomyces cerevisiae defective in excision of pyrimidine dimers, rad1, rad2, rad3, rad4, rad10, and rad16, as well as the extracts of the wild-type strain RAD+, display ultraviolet-endonuclease activity.

Proc Natl Acad Sci U S A, 1980 Apr, 77(4), 1814 - 7
Fatty acid-requiring mutant of Saccharomyces cerevisiae defective in acetyl-CoA carboxylase; Roggenkamp R et al.; The isolation and biochemical properties of a Saccharomyces cerevisiae mutant (acc1-167) defective in acetyl-CoA carboxylase {acetyl-CoA:carbon-dioxide ligase (ADP forming), EC 6.4.1.2} activity are described . The mutant is deficient in de novo biosynthesis of long-chain fatty acids and specifically requires a saturated fatty acid of chain length 14-16 C atoms for growth . Fatty acid synthetase levels were normal, but the acetyl-CoA carboxylase specific activity of the purified enzyme was reduced to approximately 5% compared to wild-type yeast . Upon sodium dodecyl sulfate/polyacrylamide gel electrophoresis the purified mutant enzyme migrated as a single band and was essentially indistinguishable from the wild-type enzyme . The study of acetyl-CoA carboxylase partial activities revealed that the biotin incorporation capacity and the transcarboxylase partial activity were unaffected whereas the biotin carboxylase component enzyme exhibited less than 10% of wild-type specific activity . This biotin carboxylase mutational deficiency could be ascribed to a more than 90% reduction of Vmax and to a comparable increase in the Km value for ATP, which was accompanied by an increased requirement for Mg2+ . It is concluded that acc1-167 contains a structural gene mutation in the biotin carboxylase domain of acetyl-CoA carboxylase.

Mol Cell Biochem, 1980 Mar 20, 30(1), 7 - 26
Coenzyme A-synthesizing protein complex of Saccharomyces cerevisiae; Bucovaz ET et al.; The coenzyme A-synthesizing protein complex (CoA-SPC) is a multienzyme complex of Saccharomyces cerevisiae (Bakers' yeast), which has a molecular weight in excess of 200,000 as determined by Sephadex G-200 column chromatography . This multienzyme complex, which is insoluble in the crude yeast cell lysate, has been purified 229-fold . A cellular component of the yeast cell lysate, referred to as t-Factor, with a molecular weight of 400-1000 and chloride ion are involved in the solubilization of CoA-SPC . The CoA-SPC requires L-cysteine, D-pantothenic acid and ATP as substrates . The terminal CoA-SPC-bound intermediate is dephospho-CoA, which is subsequently phosphorylated and released from the complex as CoA . The sequence of reactions for the synthesis of CoA by the CoA-SPC differs significantly from those previously proposed for other systems . It could be that the reaction sequence is unique for the yeast cell.

Arch Microbiol, 1980 Mar, 125(1-2), 89 - 95
The effect of sulfite on the yeast Saccharomyces cerevisiae; Schimz KL; After a short period of tolerance, living cells of Saccharomyces cerevisiae were irreversibly damaged by low concentrations of sulfite . The length of the period of tolerance and the rate of the damaging effect depended on the concentration on sulfite, pH-value, temperature, the physiological state of the cells, and incubation time . Inhibitors of protein synthesis and mitochondrial ATP synthesis did not alter the deleterious effect of sulfite on living cells . Furthermore, cell damage leading to inhibition of colony formation occured under aerobic as well as under anaerobic conditions . Prior to cell inactivation sulfite induced the formation of respiratory deficient cells . The active agent was shown to be SO2.

J Bacteriol, 1980 Mar, 141(3), 1170 - 7
Altered immunochemical reactivity of Saccharomyces cerevisiae a-cells after alpha-factor-induced morphogenesis; Lipke PN et al.; Antibodies were raised against Saccharomyces cerevisiae a-cells that had been exposed to the sex pheromone, alpha-factor . After adsorption of the antiserum with diploid cells, antibodies remained that reacted specifically with the mannan from haploid cells . The characteristic determinant was observed in mannan from pheromone-treated a-cells, in mannan from untreated alpha-cells, and at a much lower concentration, in mannan from control a-cells . The antigens from these three mannans appeared to be identical . The determinant was destroyed by mild-acid hydrolysis or periodate oxidation, but not by proteolysis or digestion with exo-alpha-mannanase . Mutants with altered mannan were unable to express the antigen . Complete acid hydrolysates mannan from alpha-factor-treated a-cells contained mannose, glucose, and N-acetylglucosamine . Partial acid hydrolysis, under conditions that destroyed the antigenic determinant, released only mannose and mannobiose . The mannose fraction was labeled to high specific activity during response of a-cells to alpha-factor if radioactive glucose was the carbon source . Neither alpha- not beta-D-mannopyranosyl phosphate was a hapten . The results are consistent with the presence of a haploid-specific antigen containing an acid-labile mannose determinant and show that the amount of this antigen in a-cell mannan is increased in response to alpha-factor.

J Bacteriol, 1980 Mar, 141(3), 1041 - 6
Ornithine decarboxylase activity and cell cycle regulation in Saccharomyces cerevisiae; Kay DG et al.; In the yeast Saccharomyces cerevisiae, the specific activity of the enzyme ornithine decarboxylase (ODC) was correlated with overall growth status . The activity of ODC was highest in actively growing cells, whereas the specific activity was lower in slow-growing cultures limited for nitrogen or inhibited by low concentrations of cycloheximide . Specific activities of ODC were also low in cultures arrested in the stationary phase (in the G1 portion of the cell cycle) by starvation for required nutrients . Although correlated with overall growth, ODC activity was not required for growth or cell cycle regulation . Cells continued to grow in the presence of the polyamine spermidine or spermine, which markedly reduced ODC specific activities . Thus, high levels of ODC activity were not necessary for growth, nor were decreased ODC specific activities sufficient to cause cells to arrest in G1 . Conversely, one agent (o-phenanthroline) which causes growing cells to arrest in G1 did so with no effect on ODC specific activity . Therefore, ODC specific activity changes are not necessary for cell cycle regulation but simply reflect the normal growth status of cells.

J Lipid Res, 1980 Mar, 21(3), 309 - 15
The extraction of inositol-containing phospholipids and phosphatidylcholine from Saccharomyces cerevisiae and Neurospora crassa; Hanson BA et al.; By use of fungi grown in the presence of {3H}-inositol and {14C}choline, we have explored methods for the quantitative extraction of inositol-containing phospholipids and phosphatidylcholine . Slightly alkaline mixtures of both ethanol-water and ethanol-diethylether-water at elevated temperatures were shown to effectively extract these lipids from intact Saccharomyces cerevisiae and Neurospora crassa . Some previously published procedures fail to completely extract to very polar phosphoinositol-containing sphingolipids of these organisms . Trichloroacetic acid can be used with caution in killing cells prior to extraction; lipid destruction can occur at elevated concentrations and temperatures . Complete extraction of these very polar lipids with polar solvents also results in an extract containing significant amounts of non-lipids.

J Bacteriol, 1980 Mar, 141(3), 1086 - 97
Assembly of the mitochondrial membrane system: isolation of mitochondrial transfer ribonucleic acid mutants and characterization of transfer ribonucleic acid genes of Saccharomyces cerevisiae; Berlani RE et al.; A method is described for isolating cytoplasmic mutants of Saccharomyces cerevisiae with lesions in mitochondrial transfer ribonucleic acids (tRNA's) . The mutants were selected for slow growth on glycerol and for restoration of wild-type growth by cytoplasmic "petite" testers that contain regions of mitochondrial deoxyribonucleic acid (DNA) with tRNA genes . The aminoacylated mitochondrial tRNA's of several presumptive tRNA mutants were analyzed by reverse-phase chromatography on RPC-5 . Two mutant strains, G76-26 and G76-35, were determined to carry mutations in the cysteine and histidine tRNA genes, respectively . The cysteine tRNA mutant was used to isolate cytoplasmic petite mutants whose retained segments of mitochondrial DNA contain the cysteine tRNA gene . The segment of one such mutant (DS504) was sequenced and shown to have the cysteine, histidine, and threonine tRNA genes . The structures of the three mitochondrial tRNA's were deduced from the DNA sequence.

Nature, 1980 Feb 28, 283(5750), 835 - 40
Abnormal expression of chromosomal rabbit beta-globin gene in Saccharomyces cerevisiae; Beggs JD et al.; A 5.1 kilobase-pair segment of rabbit chromosomal beta-globin DNA was joined to pJDB219, a plasmid consisting of pMB9, the 2-mu yeast plasmid and the yeast leu-2 gene . Saccharomyces cerevisiae transformed with the globin DNA-containing hybrid produced beta-globin-specific RNA . As compared to mature beta-globin mRNA, these transcripts lacked 20-40 nucleotides from the 5' end, contained all of the small intron and extended to about the middle of the large intron . Thus, no splicing of the primary beta-globin transcript could be detected in the yeast cells.

J Biol Chem, 1980 Feb 25, 255(4), 1542 - 6
Reactions of asparaginase II of Saccharomyces cerevisiae . A mechanistic analysis of hydrolysis and hydroxylaminolysis; Dunlop PC et al.; Detailed kinetic analysis was performed on asparaginase II, a cell wall glycoprotein from Saccharomyces cerevisiae . The enzyme was highly active in the hydrolysis and hydroxylaminolysis reactions with D- and L-asparagine and with a variety of N-substituted analogues . The data from studies involving pH dependencey, substrate saturation, and product inhibition support the hypotheses that (a) the yeast asparaginase mechanism proceeds via an acyl enzyme intermediate; (b) an ionizable group on the enzyme, pK approximately 6.0, is involved in the acylation and deacylation reactions; and (c) yeast asparaginase II is a peptidoasparaginase.

J Biol Chem, 1980 Feb 25, 255(4), 1526 - 35
The stringent and relaxed phenomena in Saccharomyces cerevisiae; Kelker HC et al.; We present here a detailed analysis of the effect of amino acid starvation and the addition of cycloheximide on RNA metabolism of yeast cells and spheroplasts . These effects have been studied at the level of uridine phosphorylation, methylation of rRNA, and biosynthesis of 35 S, 4 S, and 5 S RNA species . Amino acid starvation inhibits the phosphorylation of uridine assigned for RNA synthesis more than that for other metabolic processes . This implies that a salvage pathway for the synthesis of UMP and CMP is regulated by the rate of transcription and perhaps is localized in the nucleus . The rate of rRNA methylation is not coupled with the rate of transcription; therefore, quantitation of 35 S RNA synthesis (yeast rRNA primary transcript by {methyl-3H}methionine labeling is unreliable . Biosynthesis of 35 S RNA ceases immediately after the cells are transferred to an amino-acid-deficient medium; at a later time 4 S and 5 S RNAs are also inhibited . Therefore, coordination and noncoordination in the stringent response of these RNA species depend upon the time of starvation . Although addition of a small dose (less than 1.0 microgram/ml) of cycloheximide to starved yeast spheroplasts does not alter the rate of uridine phosphorylation, it increases the rate of entrance of uridine into total RNA . This effect is of greater magnitude in 4 S and 5 S than in 35 S RNA . Since the drug does not alter the rate of decay of 35 S RNA that takes place in starvation, it has a selective effect on transcription . A similar small dose, however, produces inhibition of transcription of all these RNA species in nonstarved conditions . This opposite effect of the drug appears to be a characteristic feature of RNA metabolism in eukaryotes.

Mutat Res, 1980 Feb, 77(2), 143 - 8
Mutagenicity of N-nitrosopiperazine derivatives in Saccharomyces cerevisiae; Larimer FW et al.; The mutagenic properties of 8 N-nitrosopiperazines were examined in Saccharomyces cerevisiae . Forward mutations to canavanine resistance and reversions of his1-7 were induced by N'-methyl-N-nitrosopiperazine, dinitrosopiperazine, 2-methyldinitrosopiperazine, 2,5-dimethyldinitrosopiperazine, and 2,6-dimethyldinitrosopiperazine, in the presence of rat-liver homogenate . N-nitrosopiperazine, 2,3,5,6-tetramethyldinitrosopiperazine, and 4-benzoyl-3,5-dimethyldinitrosopiperazine were non-mutagenic.

Mol Gen Genet, 1980 Feb, 177(3), 541 - 4
A new mutant of the yeast Saccharomyces cerevisiae defective in excision of UV-damaged sites in DNA; Bekker ML et al.; An UV-sensitive yeast mutant, uvs12, with almost unchanged sensitivity to gamma-irradiation and methylmethane sulphonate was obtained . uvs12, non allelic to any of the known UV-sensitive mutants from radI to rad21 is defective in early steps of excision repair . This inference is based on the fact that after 4-5 h post-irradiation incubation unexcised pyrimidine dimers are retained in nuclear DNA, which follows from two independent tests: the retention of UV-endonuclease-sensitive sites and enhanced survival after photoreactivation.

Arch Microbiol, 1980 Feb, 124(2-3), 243 - 7
Ribonuclease activity during G1 arrest of the yeast Saccharomyces cerevisiae; McFarlane ES; When cells of the yeast, Saccharomyces cerevisiae, were deprived of nitrogen, a condition leading to G1 arrest, there was an immediate increase in the levels of total ribonuclease (RNase) activity within these cells . During starvation, only the cells arrested in G1 showed increased RNase activity . Although the RNase activities of extracts of starved and actively growing cells were similarly influenced by pH, the activities of starved cells were less stable on both storage and heating . Differences were also noted in substrate specificity . The results of this study suggest that arrest within G1 may increase RNase activity . However, all RNases did not appear to be influenced equally, since the total pool of RNase activity from log phase and G1 arrested cells showed differences in stability and substrate specificity.

J Bacteriol, 1980 Feb, 141(2), 999 - 1002
Caffeine resistance of Saccharomyces cerevisiae; Bard M et al.; Four caffeine-resistant haploid isolates, two resistant to 50 mM caffeine and two resistant to 100 mM caffeine, were genetically analyzed . Complementation and tetrad analysis indicated that all four mutations are alleles of the same locus . All four isolates demonstrated incomplete dominance when hybridized to the wild-type strain and dominance of high to low resistance when hybridized to one another . Differences in caffeine resistance were found between wild-type grande cells and its petite derivative.

J Bacteriol, 1980 Feb, 141(2), 508 - 27
Function of positive regulatory gene gal4 in the synthesis of galactose pathway enzymes in Saccharomyces cerevisiae: evidence that the GAL81 region codes for part of the gal4 protein; Matsumoto K et al.; A meiotic fine structure map of the gal4 locus was constructed, which extended over 0.44 units on the chromosome (units in percent frequency of supposed recombination) . Several nonsense gal4 mutations (four UAA and two supposed UGA {gal4-62 and gal4-69}) were placed at various sites on the map . In reversion experiments with 20 independently isolated gal4 mutants, only the gal4-62 and gal4-69 alleles, which are located at the same site on the map, could revert to overcome the superrepression of gal80s-1 spontaneously with a frequency of approximately 4 x 10(-7) . Secondary mutations in the revertants occurred in the region of gal4-62 or were due to unlinked suppressors . A total of 15 GAL81 mutations in 19 isolates were found to be located in the same region as gal4-62 by three-point crosses with the aid of gal4 mutants; the other four could not be analyzed . The reverted gal4 gene and GAL81 mutations were semidominant over the wild-type GAL4+ allele and fully dominant over a nonsense gal4 mutation . Four suppressors (one dominant and three recessive) effective against gal4-62 and gal4-69 were isolated . The dominant suppressor was also effective against three independent, authentic auxotrophic UGA nonsense mutations, and one of the three recessive suppressors were effective against the authentic auxotrophic UAA and UAG mutations . These results strongly support the idea that the gal4 locus is expressed constitutively and codes for a regulatory protein . The GAL81 site mapped inside the locus codes for a part of the gal4 protein but does not work as an operator.

Proc Natl Acad Sci U S A, 1980 Feb, 77(2), 785 - 9
N,N'-dicyclohexylcarbodiimide binds specifically to a single glutamyl residue of the proteolipid subunit of the mitochondrial adenosinetriphosphatases from Neurospora crassa and Saccharomyces cerevisiae; Sebald W et al.; The N,N'-dicyclohexylcarbodiimide-binding proteolipid subunit of the mitochondrial adenosinetriphosphatases (ATP phosphohydrolase, EC 3.6.1.3) of Neurospora crassa and Saccharomyces cerevisiae were purified from mitochondria incubated with the radioactively labeled inhibitor . The specifically labeled subunit was cleaved with cyanogen bromide and N-bromosuccinimide, and the resultant fragments were separated by gel chromatography in the presence of 80% (vol/vol) formic acid . The N,N'-dicyclohexylcarbodiimide label was recovered in each organism exclusively in a 17-residue fragment . Further analysis by automated solid-phase Edman degradation revealed that the bound label was present at only one position, corresponding to a glutamyl residue . The N,N'-dicyclohexylcarbodiimide-modified glutamyl residue is the only identical acidic position in both proteins and occurs in the middle of a hydrophobic sequence of about 25 residues.

Eur J Biochem, 1980 Feb, 104(1), 119 - 23
Glutathione metabolism in relation to the amino-acid permeation systems of the yeast Saccharomyces cerevisiae . Occurrence of gamma-glutamyltranspeptidase: its regulation and the effects of permeation mutations on the enzyme cellular level; Penninckx M et al.; A careful enzyme specificity analysis has revealed the presence of a typical gamma-glutamyltranspeptidase in the yeast Saccharomyces cerevisiae . The enzyme cellular level is low in the presence of NH4+ as a sole nitrogen source and rises when individual amino acids are used as nitrogen sources . The gamma-glutamyltranspeptidase appears to be repressed by NH+4 and escapes to the regulatory circuits under the control of glutamine and the glutamate-dehydrogenase . NH+4 complex . The transpeptidase cellular level is unaffected in mutants which have lost the general amino acid permease and specific systems for L-arginine and L-lysine . In contrast, a low enzyme level is observed when growing an apf mutant on urea; this mutant is most probably affected in a common element shared by all the amino acid permeation systems . Urea appears to be a nitrogen source which promotes a high transpeptidase level in the wild-type strain . The reported data are discussed in the light of the current theories about the intervention of glutathione metabolism in the translocation of amino acids.

Antonie Van Leeuwenhoek, 1980, 46(6), 565 - 76
The growth of Saccharomyces cerevisiae CBS 426 on mixtures of glucose and ethanol: a model; Bonnet JA et al.; Saccharomyces cerevisiae CBS 426 was grown in continuous culture in a defined medium with a mixture of glucose and ethanol as carbon source . Growth on ethanol as the sole carbon source was only possible after the addition of a small amount of glutamic acid . The flows of glucose, ethanol, oxygen, carbon dioxide and biomass to and from the system were measured and a model for the growth of the yeast on the carbon sources constructed . The model is shown to allow independent estimation of YATP and P/O . YATP is not independent of the substrate used, but the amount of ATP used in the production of biomass from the monomers is approximately the same for growth on ethanol and on glucose.

Biokhimiia, 1980 Jan, 45(1), 11 - 9
{Physico-chemical and functional properties fo intramitochondrial polyribosomes of the yeast Saccharomyces cerevisiae}; Babich SG et al.; Different methods of separation of mitochondrial polyribosomes of the yeast Saccharomyces cerevisiae from the admixtures of cytoplasmic polyribosomes firmly bound to the outer mitochondrial membrane has been carried out . It has been shown that treatment of mitochondria with 0.5 M KCl -- 1 mM puromycin alone allows to obtain a highly purified fraction of mitochondrial polyribosomes (Sw, 20 = 100--200S), consisting of 2--3 monomers . Gel-filtration under denaturing conditions of nascent polypeptides bound to mitochondrial polyribosomes has revealed a predominance of polypeptides with molecular weights of 10000--11000 . Isoelectrofocusing of labelled polypeptides in the presence of ampholines (pH 3--10) has demonstrated that they are predominantly focussed in the pH region around 9.0 and, consequently, possess basic properties.

Cytobios, 1980, 29(113), 29 - 36
Effect of cryo-protective agents on the growth and ultrastructure of Saccharomyces cerevisiae; Srivastava KC et al.; When suspended in a glucose medium supplemented with varying amounts of DMSO, ethylene glycol, glycerol, lactose and sodium chloride at its optimum temperature of 30 degrees C, a diploid strain of Saccharomyces cerevisiae gave a mean generation time inversely proportional to the increased concentrations of these anti-freeze compounds . No growth was attained at 0 degrees C and -5 degrees C, and mixtures of the compounds did not support any growth even at 30 degrees C . At 0 degrees C and -5 degrees C with increasing percentages of the individual compounds, and at 30 degrees C, 0 degrees C and -5 degrees C, with mixtures of the compounds, a significant decrease in survival was obtained . As compared to cells grown in the absence of antifreeze compounds, electron microscopy of the cells which grew at 30 degrees C in the presence of antifreeze compounds showed thicker cell walls, highly convoluted plasmalemma, vacuoles filled with electron-dense fibrous material, spherosomes, poorly developed mitochondria and many vesicles.

Mol Gen Genet, 1980, 180(3), 591 - 6
UV-induced mitotic recombination and its dependence on photoreactivation and liquid holding in the rad6-1 mutant of Saccharomyces cerevisiae; Haladus E et al.; Spontaneous and UV-induced mitotic recombination was compared in diploids homozygous for rad6-1 mutation and in the wild-type strain carrying heterozygous markers for detecting gene conversion (hom2-1, hom2-2) and crossing over (ade1, ade2) . Diploids homozygous for rad6-1 mutation were characterised by an elevated level of spontaneous and UV-induced mitotic recombination, particularly the intergenic events . Exposure of UV-irradiated strains to visible light resulted in an increased survival and decreased level of mitotic recombination . Liquid holding (LH) differentially affected frequency of mitotic intergenic and intragenic recombination in mutant and wild-type strains, being without any significant effect on cell survival . In a mutant strain intragenic recombination is significantly increased, intergenic only slightly . In the wild-type strain intragenic recombination is slightly decreased but intergenic is not changed by LH . Visible light applied after LH had no effect on survival and mitotic recombination in the wild type, while in the mutant strain photoreactivability of survival was fully preserved and accompanied by a decrease in the frequency of intragenic and intergenic recombination . The results suggest that metabolic pathways responsible for restoring cell survival are independent of or only partly overlapping with those concerning recombination events.

Genetika, 1980, 16(11), 2058 - 60
{Effect of Saccharomyces cerevisiae RAD54 mutation on gamma ray-induced reciprocal mitotic recombination}; Kasinova GV; The effect of gamma-irradiation on mitotic segregation and intergenic reciprocal mitotic recombination between the centromere and the ade2 locus of rad sensitive Saccharomyces mutant has been studied in comparison with the wild type RAD . These strains homozygous for either RAD or rad54 gene, showed gamma-rays induced mitotic segregation and reciprocal mitotic recombination . Within a dose range resulting in an equal survival, fraction induced mitotic segregation and intergenic reciprocal recombination was greater for the RAD strain . Rad54 mutation increased the spontaneous mitotic segregation and mitotic reciprocal recombination in comparison with the rad strain.

Chromosoma, 1980, 81(3), 379 - 91
Folded chromosomes of Saccharomyces cerevisiae: comparison of response to sporulation medium, arrest at start, and G0 arrest; Pinon R et al.; Folded chromosome phenotypes have been examined and compared in four cell-division-cycle (cdc) mutants during transitions between cycling and non-cycling states . The two start mutants, cdc 28 and cdc 25, can undergo G0 arrest at the restrictive temperature . Arrest at start, defined by the cdc 28 and cdc 25 block points, is distinguishable from G0 arrest . Arrest at the cdc 28 and cdc 25 block points can also be distinguished from each other: folded chromosomes appear to be destabilized at the cdc 25 block, but are stable at the cdc 28 arrest point . On the other hand, folded chromosomes from cdc 28 in sporulation medium at the restrictive temperature appear unstable, while chromosomes from cdc 25 are stable . The G1 arrest mutants, cdc 4 and cdc 7, can undergo G0 arrest at the restrictive temperature . In sporulation medium no meiotic replication form is detected at the restrictive temperature, although incorporation of labeled precursors into nuclear DNA does take place . A schematic model incorporating these various findings is presented.

Mol Gen Genet, 1980, 179(3), 703 - 5
The RAD52 gene is not required for the function of the DEL1 mutator gene in Saccharomyces cerevisiae; Liebman SW et al.; The DEL1 mutator inb Saccharomyces cerevisiae leads to the formation of deletions adjacent to itself (Liebman et al . 1979) . Here we show that the frequency of these DEL1-promoted deletions is not altered by the presence of the recombination-deficient mutation, rad52-l . This indicates that generalized recombination is not required for the formation of deletions in DEL1 yeast strains.

Genetika, 1980, 16(5), 787 - 91
{Study of induction of mitochondrial mutations in Saccharomyces cerevisiae yeasts following exposure to ethyl alcohol}; Bandas EL et al.; The kinetics of the killing and petite-inducing effects of ethanol has been studied at 6-30% concentrations . The results obtained indicate that the ploidy of cells or holding them under no-growth conditions do not influence on their survival . Ethanol increased the number of respiration-deficient cells from spontaneous level (0.46%) up to nearly half of all survivors at 24% and 30% ethanol concentrations . The genetic analysis has shown the mitochondrial nature of induced respiration deficiency.

Z Allg Mikrobiol, 1980, 20(5), 315 - 24
Effects of the antimicrotubular cancerostatic drug nocodazole on the yeast Saccharomyces cerevisiae; Kunkel W; Nocodazole completely inhibited cell division of Saccharomyces cerevisiae, contrary to methyl-benzimidazole-2-ylcarbamate, estimated by cell counting . Growth as measured by turbidity and dry weight estimations, however, was not influenced . Treatment for two hours with nocodazole interrupts the budding cycle of the yeast within a period when bud and mother cells have reached equal sizes . Dependent on duration of nocodazole treatment stretched or dumb-bell shaped nuclei are localized between bud and mother cell or two daughter nuclei are present . It has been shown by electron microscopy that nocodazole neither destroyed karyo- nor ground-plasmic microtubules . The spindle pole bodies (spb), however, reached double the normal size approximately.

Z Naturforsch {C}, 1980 Jan-Feb, 35(1-2), 168 - 70
The induction of a ribosomal ribonuclease in Saccharomyces cerevisiae; Schulz-Harder B et al.; The ribosomal ribonuclease of yeast is induced after a withdrawal of glucose . Cycloheximide inhibits the synthesis of the enzyme under conditions of induction but antimycin shows no effect . Hence, the increase of the ribonuclease activity during growth of yeast is due to newly synthesized enzyme, and the induction does not depend on respiration.

Genetika, 1980, 16(3), 408 - 17
{Genetico-biochemical study of the acid phosphatases of Saccharomyces cerevisiae yeasts . X . Analysis of mutations arising in gene acp3}; Kozhin SA et al.; Mutations leading to decrease or absence of orthophosphate-repressible acid phosphatase activity have been studied . It is shown that these mutations can arise in three genes: acp1, acp2 and acp3, which are not linked . Genes acp1 and acp2 have been studied previously; the existence of the gene acp3 is demonstrated in this paper . It is established that all mutations in the acp3 gene are recessive, are leaky and epistatic to the constitutive mutations in all known regulatory genes for acid phosphatase II synthesis - acp4, acp80, acp81, acp82, acp83, and acp84 . The gene acp3 is not linked with these regulatory genes, but it is closely linked with the structural gene for constitutive acid phosphatase - pho1 (D=0.33+/-0.20 cM) . The pho1 gene has been recently located on the right arm of chromosome II on the left of the gene lys2 . Mutations lacking activity of constitutive and repressible acid phosphatases simultaneously have been found . It is shown that these mutations are allelic to mutations in the gene acp3 and pho1 simultaneously . Two hypotheses are proposed about the role of the gene acp3: the gene controls the positive factor for the repressible acid phosphatase synthesis or the structure of the enzyme.

Mol Gen Genet, 1980, 178(3), 713 - 6
An enrichment method for heme-less mutants of Saccharomyces cerevisiae based on photodynamic properties of Zn-protoporphyrin; Grimal D et al.; A new and widely applicable technique has been elaborated for enrichment of mutants of Saccharomyces cerevisiae deficient in porphyrin and heme synthesis . The method is based on selective photooxidative killing of the wild-type cells, sensitited by Zn-protoporphyrin synthesized and accumulated in wild-type cells under defined conditions . Using a single cycle of selection, heme-deficient mutants have been obtained with a frequency of 2-2.3%.

Mol Gen Genet, 1980, 178(2), 357 - 60
Ribosomal precursor RNA metabolism and cell division in the yeast Saccharomyces cerevisiae; Johnston GC et al.; When shifted from 23 degrees C to 36 degrees C, cells of a non-temperature-sensitive strain of yeast arrest transiently in G1 before continuation of the cell division cycle . When shifted to 36 degrees C, cells harboring a temperature-sensitive rna mutation behave similarly . Others have shown that temperature shift transiently decreases the rates of production and processing of ribosomal precursor RNA (rpreRNA) . Production of rpreRNA is soon restored to normal levels in these strains, but normal processing of these repreRNA transcripts is restored only in non-temperature-sensitive strains . Therefore these experiments serve to eliminate from cell cycle considerations the involvement of processing of rpreRNA, while maintaining the established correlation between cell cycle behavior and rpreRNA production.

Mol Gen Genet, 1980, 177(4), 675 - 80
Recessive nonsense-suppression in yeast Saccharomyces cerevisiae: the study of 80 S ribosomes accumulated in suppressor strain under non-permissive conditions; Surguchov AP et al.; The shift of recessive suppressor mutant of yeast Saccharomyces cerevisiae from permissive to restrictive conditions is accompanied by polysome decay and accumulation of 80 S ribosomes (Smirnov et al., 1976) . In this paper some properties of 80 S ribosomes are studied . It is demonstrated that polysome decay under non-permissive conditions is not the consequence of the impairment of RNA synthesis . More than 70% of 80 S ribosomes accumulated under non-permissive conditions contain bound peptidyl-tRNAs localized in P-ribosomal site . tRNA moiety of bound peptidyl-tRNA is able to accept all 20 natural amino acids after chemical deacylation . Therefore it is not a specific isoacceptor species but rather total tRNA that is bound to ribosomes . The polypeptide residues of these peptidyl-tRNAs are heterogeneous in size . Their molecular weights are comparable with the molecular weights of the completed polypeptides . Some of the 80 S ribosomes accumulated under non-permissive conditions contain poly-A+ RNA . In conclusion, possible mechanism of the impairment of translation under non-permissive conditions in recessive suppressor strain is discussed.

Mol Gen Genet, 1980, 177(4), 577 - 80
Recombinagenic and mutagenic effects of sunlamp (UV-B) irradiation in Saccharomyces cerevisiae; Hannan MA et al.; Genetic effects of pyrex-filtered sunlamp irradiation (primarily UV-B, lambda approximately 280-320 nm which is present in natural sunlight) were studied in diploid and haploid yeast strains designed to monitor the incidence of mitotic crossing over, mitotic gene conversion and mutations . Exposure to UV-B was found to be very effective in inducing all three types of genetic endpoints . These effects could be observed even after UV-B treatments resulting in no cellular inactivation . Comparative studies using filtered sunlamp radiation and germicidal UV radiation (lambda approximately 254 nm) indicated that, at an equivalent survival level (including exposures causing little or no cell death), UV-B induced more gene convertants and that the kinetics of mutations induced by the two lights are demonstrably different.

Biochim Biophys Acta, 1980, 613(1), 52 - 61
Benzo(a)pyrene hydroxylase from Saccharomyces cerevisiae . Substrate binding, spectral and kinetic data; Woods LF et al.; Saccharomyces cerevisiae, brewer's yeast, produces a microsomal benzo(a)pyrene hydroxylase when grown at high glucose concentrations of which the haemoprotein, cytochrome P-450 (RH, reduced-flavoprotein:oxygen oxidoreductase (RH-hydroxylating) EC 1.14.14.1) is a component . We report here kinetic data derived from Lineweaver-Burk plots of benzo(a)pyrene hydroxylation . The Michaelis constant was decreased by growth of the yeast in the presence of benzo(a)pyrene showing the induction of a form of the enzyme more specific for this compound . NADPH or cumene hydroperoxide could be used as cofactors by this enzyme, although with different Km and V values for benzo(a)pyrene . A solubilised and a solubilised, immobilised enzyme preparation were capable of benzo(a)pyrene hydroxylation, using cumene hydroperoxide but not NADPH as the cofactor . Benzo(a)pyrene was found to produce a modified type I spectral change with yeast and rat liver microsomes . The interaction of benzo(a)pyrene with cytochrome P-450 was investigated further by means of an equilibrium gel filtration technique . There appeared to be 20 binding sites per mol ofcytochrome P-450 for benz(a)pyrene, in both yeast and rat liver microsomes.

Histochem J, 1980 Jan, 12(1), 57 - 69
Glucose repression and autolysis of Saccharomyces cerevisiae cells: alterations in the cytochemical localization of acid phosphatase; Rainina EI et al.; Alterations in the localization of acid phosphatase in Saccharomyces cerevisiae during glucose repression and during autolysis have been studied . Cell morphology becomes distinctly changed after only 2 h in the presence of high glucose concentration while after 3 h of glucose repression the majority of the mitochondrial structures resemble promitochondria . Yeast cells repressed for 6 h contain almost completely degraded mitochondrial structures and numerous lipid droplets in the central vacuole and cytoplasm . Destruction of mitochondria is accompanied by the accumulation of acid phosphatase in these organelles and in the cytoplasm, whereas its activity in the central vacuole is lowered, most probably because of the leakage of the enzyme into the cytoplasm . No preferential breakdown of mitochondria is observed during autolysis . On the contrary, mitochondria are apparently the last to be degraded . Digestion of cytoplasmic regions and membranous elements occurs intravacuolarly after sequestration by protrusions of the central vacuole which are formed at the initial stages of autolysis . Acid phosphatase is not released from the central vacuole, suggesting indirectly that vacuole enzymes do not migrate into the cytoplasm during autolysis.

Mol Gen Genet, 1980 Jan, 177(2), 199 - 205
Denaturation mapping of the ribosomal DNA of Saccharomyces cerevisiae; Cramer JH et al.; The thermal melting profile of purified Saccharomyces cerevisiae ribosomal DNA (rDNA) is biphasic indicating considerable intramolecular heterogeneity in base composition . The first phase of the transition, about 20% of the total hyperchromic shift, has a Tm of 80.6 degrees C and the second phase has a Tm of 87.3 degrees C, corresponding to GC contents of 28 and 44%, respectively . The Tm of the nonribosomal nuclear DNA, called alpha DNA, is 85.7 degrees C . This heterogeneity in GC distribution in the rDNA is also reflected in its denaturation map . A denaturation map of the 5.6 X 10(6) dalton rDNA SmaI restruction fragment, which represents monomer units of the rDNA, shows that specific regions of the repeating unit denature more readily than the remainder and apparently have a significantly higher AT content . By aligning the rDNA denaturation map with the restriction endonuclease map, we have been able to determine that the AT-rich segments are localized in the transcribed and nontranscribed spacer regions of the rDNA repeating unit . Buoyant density determinations of individual rDNA restriction fragments corroborate the locations of AT-rich regions . A denaturation map of the tandem repeating units in higher molecular weight rDNA has also been constructed and compared with the map of the SmaI fragment . The results show that the repeating units are uniform in size, that they are not separated by large heterogeneous regions, and that they are arranged in head-to-tail array.

Proc Natl Acad Sci U S A, 1980 Jan, 77(1), 527 - 30
"Superkiller" mutations suppress chromosomal mutations affecting double-stranded RNA killer plasmid replication in saccharomyces cerevisiae; Toh-E A et al.; Saccharomyces cerevisiae strains carrying a 1.5 x 10(6)-dalton double-stranded RNA genome in virus-like particles (killer plasmid) secrete a protein toxin that kills strains not carrying this plasmid . At least 28 chromosomal genes (mak genes) are required to maintain or replicate this plasmid . Recessive mutations in any of four other chromosomal genes (ski for superkiller) result in enhanced toxin production . We report that many ski- mak- double mutants are able to maintain the killer plasmid, indicating that the SKI products have an effect on plasmid replication . The ski1-1 mutation suppresses (bypasses) all mak mutations tested except mak16-1 . A variant killer plasmid is described that confers the superkiller phenotype and, like chromosomal ski mutations, makes several mak genes dispensable for plasmid replication.

Mech Ageing Dev, 1980 Jan, 12(1), 47 - 52
Calendar life span versus budding life span of Saccharomyces cerevisiae; Muller I et al.; This investigation is concerned with the internal factors governing the life span of individual yeast cells . The life span may be limited either by the number of buds a cell can produce or by internal measurement of metabolic time . The natural relationship between the number of cells a single cell can produce and the passage of time was modified by three different kinds of treatment: (1) by cooling the cells for several hours each day; (2) by preculturing the cells in media which inhibit cell division before allowing logarithmic growth; and (3) by culturing the cells in a medium which reduces the rate of budding . All these methods led to a prolongation of chronological life span, but the life span measured by the number of buddings remained remarkably constant . We therefore conclude that there is some kind of factor involved in the budding process which determines life span.

J Bacteriol, 1980 Jan, 141(1), 342 - 9
Lipid-mediated glycosylation of endogenous proteins in isolated plasma membrane of Saccharomyces cerevisiae; Welten-Verstegen GW et al.; A highly purified plasma membrane fraction from Saccharomyces cerevisiae was obtained by centrifugation on discontinuous sucrose and Urografin gradients . This plasma membrane fraction was capable of glycosylating endogenous proteins . It is shown that glycolipids play an intermediate role in these glycosylation reactions; with uridine 5'-diphosphate-N-acetylglucosamine as sugar donor the intermediate lipids possessed stability towards alkali and chromatographic mobilities similar to polyprenyl diphosphate N-acetylglucosamine and polyprenyl diphosphate di-N-acetylchitobiose.

J Bacteriol, 1980 Jan, 141(1), 270 - 4
Genetic mapping of arg1 and arg8 in Saccharomyces cerevisiae by trisomic analysis combined with interallelic complementation; Hilger F et al.; Through use of multiply disomic strains, the genes arg1 and arg8 were excluded from all of chromosomes I to XVII except (i) XV and (ii) IX and XV, respectively . Further aneuploid analyses showed that these two genes were on the same chromosome . By tetrad analysis, arg1 was shown to be linked to SUP3 on the left arm of chromosome XV (parental ditype:nonparental ditype:tetratype = 74; 6:139) and arg8 was shown to be loosely linked to arg1 (parental ditype:nonparental ditype:tetratype 72:17:220) on the same arm . The sequence of the genes on this chromosome arm is centromere-SUP3-arg8 . Because arg1 had previously been used to define an 18th chromosome, these results reestablished the minimum chromosome number in Saccharomyces cerevisiae as 17.

J Bacteriol, 1980 Jan, 141(1), 100 - 5
Transient cell cycle arrest of Saccharomyces cerevisiae by amino acid analog beta-2-DL-thienylalanine; Bedard DP et al.; When treated with the amino acid analog beta-2-DL-thienylalanine, cells of the yeast Saccharomyces cerevisiae accumulated in the G1 portion of the cell cycle at the "start" event . This G1 arrest was accompanied by a rapid decrease in the rate of labeling of ribonucleic acid (RNA) with little effect on the rate of labeling of protein . When we examined which aspect of RNA metabolism was most affected by beta-2-DL-thienylalanine treatment, we found a dramatic decrease in the production of ribosomal precursor RNA . These results are consistent with previous findings which show a correlation between G1 arrest and reduced ribosomal precursor RNA production . The G1 arrest brought about be beta-2-DL-thienylalanine was transient; cells remain arrested in G1 only for several hours . Release from G1 arrest appeared to be accompanied either by metabolism or sequestration of the analog.

Biochim Biophys Acta, 1980, 606(1), 76 - 82
P5/P5' the acidic ribosomal phosphoproteins from Saccharomyces cerevisiae; Zinker S; P5/P5', the most acidic and exchangeable phosphoproteins from the large ribosomal subunit in the yeast Saccharomyces cerevisiae, were purified from the rest of the ribosomal proteins by means of polyacrylamide gel electrophoresis . Antibodies against the pure P5/P5' proteins cross-reacted with polypeptides from the cytoplasm suggesting that a cytoplasmic pool of P5/P5' exist . The cytoplasmic polypeptides immunologically related to P5/P5' are not phosphorylated.

Biochim Biophys Acta, 1980, 595(1), 109 - 20
Amino acid uptake by Saccharomyces cerevisiae plasma membrane vesicles; Merkel GJ et al.; A procedure is described which allows for the efficient separation of Saccharomyces cerevisiae plasma membranes from other cellular membranes by discontinuous sucrose density gradient centrifugation . After vesiculization in an osmotic stabilization buffer the plasma membrane vesicles retain the ability to transport amino acids . Amino acid uptake was affected by the proton gradient dissipator m-chlorocarbonylcyanide phenylhydrazone and was dependent, in some cases, on the presence of sodium ion.

Mutat Res, 1980 Jan, 77(1), 55 - 63
Cytochrome P-450 mediated genetic activity and cytotoxicity of seven halogenated aliphatic hydrocarbons in Saccharomyces cerevisiae; Callen DF et al.; Cells of Saccharomyces cerevisiae, harvested from log-phase cultures, contain cytochrome P-450 and are capable of metabolizing promutagens to genetically active products . The activities of 7 halogenated aliphatic hydrocarbons in the yeast system have been investigated . All of the compounds tested (methylene chloride, halothane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene and s-tetrachloroethane) induced mitotic gene convertants and recombinants and, to a lesser extent, gene revertants when incubated with log-phase cells of the yeast strain D7 . An examination of the difference spectra observed upon the addition of carbon tetrachloride, halothane and trichloroethylene to whole-cell or microsomal suspensions of yeast suggested that cytochrome P-450 mediated the metabolism of the hydrocarbons tested to cytotoxic and genetically active compounds.

Proc Natl Acad Sci U S A, 1980 Jan, 77(1), 541 - 5
Isolation and sequence of the gene for iso-2-cytochrome c in Saccharomyces cerevisiae; Montgomery DL et al.; The two apocytochrome c proteins of yeast are coded for by separate genes . Iso-2-cytochrome c differs from the iso-1 protein at 17 positions within a homologous sequence of 108 amino acids . The previously cloned iso-1-cytochrome c coding sequence has been used to identify lambda-yeast recombinant phage containing the gene for iso-2-cytochrome c . The latter protein contains the dipeptide Ala-Ala which is coded for by the nucleic acid sequence G-C-N-G-C-N . The recognition specificity of restriction endonuclease Fnu4HI for G-C-N-G-C provided a rapid means of locating the region of the cloned fragment which codes for iso-2-cytochrome c . The DNA sequence of this gene has been determined and compared with that of the iso-1-cytochrome c locus . There is no intervening sequence within the gene for iso-2-cytochrome c . At 45 of the 91 positions for which iso-1- and iso-2-cytochrome c have the same amino acid, the codons differ . Such third position variation does not occur within the region coding for amino acids 70-80, the protein sequence that is also most conserved among all eukaryotic cytochromes c.

Hoppe Seylers Z Physiol Chem, 1980 Jan, 361(1), 17 - 24
Galactosamine is an inducer of Gal genes in Saccharomyces cerevisiae; Venkov PV et al.; In yeast cells galactosamine in concentrations of 0.1 1M partially inhibits the synthesis of RNA but has little effect on the protein synthesis . In vivo and in vitro studies show that galactosamine is metabolized in yeast to UDP-N-acetylhexosamines but at a reduced rate, compared to the metabolism of galactose . The addition of galactosamine to growing yeast cells leads to the induction of the galactose pathway enzymes . Studies using different mutants in the galactose genes provide evidence that galactosamine is an inducer of the galactose structural genes in yeast . The same degree of induction of galactokinase and galactotransferase, found when galactose or galactosamine were used as inducers, supports the model of coordinated regulation in the expression of the structural genes for the galactose pathway enzymes in yeast.

Acta Microbiol Pol, 1980, 29(1), 57 - 63
N, N' (p-Xylylidene)-bis-aminoguanidine (2HCI) resistant mutants in Saccharomyces cerevisiae and their relation to the amino acid transport system; Witkowska R et al.; N,N'-(p-Xylylidene)-bis-aminoguanidine 2HCl proved to be an efficient inducer of non-chromosomal petite mutation in Saccharomyces cerevisiae in either growing or non-growing conditions . A mutant Agr-7 resistant to this compound was obtained . Resistance proved to dominate over its XBAG-sensitive allele in the diploid formed in cross . Mutant Agr-7 is characterized by slow growth rate on YEPG or minimal medium and small colony size . Studies on uptake of amino acids and sugars indicate that the phenomenon of resistance is involved in alteration of the general amino acid permease activity.

Acta Microbiol Pol, 1980, 29(1), 5 - 19
Energy requirement for liquid holding recovery from UV- and DEB-induced damage in rad mutants of Saccharomyces cerevisiae; Zaborowska D et al.; Respiratory deficient (rho o) strains respond to liquid holding in buffer alone with a sharp decrease of cell survival . In buffer with 0.02% glucose rho o strains behave similarly as rho+ strains . After UV or DEB inactivation rho o strains derived from rho+ rad mutants capable of LHR in buffer alone, manifest this capacity in glucose buffer . In some respiratory proficient rad mutants LHR is enhanced or induced by holding in glucose buffer, e.g . DEB inactivated rad3, rad6 and rad14 . In such mutants the number of mitochondrial profiles was found to be 3 to 4 times lower than in the wild-type RAD or in rad mutants with LHR insensitive to glucose . This suggests that mutants with glucose-enhanced LHR are defective in energy metabolism and require exogenous energy supply for initiation of liquid holding repair capacity . In UV-irradiated JG-1 (rad1-1), rad3 and rad11 as well as in DEB-inactivated rad7, rad11, rad19 and rad20 the inability of LHR is a constitutive phenomenon and cannot be overcome by exogenous energy supply.

Biochim Biophys Acta, 1979 Dec 4, 558(2), 221 - 32
Studies on purine transport and on purine content in vacuoles isolated from Saccharomyces cerevisiae; Nagy M; The transport of purine derivatives into vacuoles isolated from Saccharomyces cerevisiae was studied . Vacuoles which conserved their ability to take up purine compounds were prepared by a modification of the method of polybase-induced lysis of spheroplasts . Guanosine greater than inosine = hypoxanthine greater than adenosine were taken up with decreasing initial velocities, respectively; adenine was not transported . Guanosine and adenosine transporting systems were saturable, with apparent Km values 0.63 mM and 0.15 mM respectively, while uptake rates of inosine and of hypoxanthine were linear functions of their concentrations . Adenosine transport in vacuoles appeared strongly dependent on the growth phase of the cell culture . The system transporting adenosine was further characterized by its pH dependency optimum of 7.1 and its sensitivity to inhibition by S-adenosyl-L-methionine . In the absence of adenosine in the external medium, {14C}adenosine did not flow out from preloaded vacuoles . However, in the presence of external adenosine, a very rapid efflux of radioactivity was observed, indicating an exchange mechanism for the observed adenosine transport in the vacuoles . In isolated vacuoles the only purine derivative accumulated was found to be S-adenosyl-L-homocysteine.

J Bacteriol, 1979 Dec, 140(3), 888 - 92
Binding of yeast killer toxin to a cell wall receptor on sensitive Saccharomyces cerevisiae; Bussey H et al.; 35S-labeled killer toxin protein bound to cells of sensitive Saccharomyces cerevisiae S14a . Strains that were resistant to toxin through mutation in the nuclear genes kre1 kre2 bound toxin only weakly . Non-radioactive toxin competed effectively with 35S-labeled toxin for binding to S14a, but did not compete significantly in the binding to mutant kre1-1 . This implied that binding to kre1-1 was nonspecific . A Scatchard analysis of the specific binding to S14a gave a linear plot, with an association constant of 2.9 x 10(6) M-1 and a receptor number of 1.1 x 10(7) per cell . Killer toxin receptors were solubilized from the cell wall by zymolyase digestion . Soluble, non-dialyzable cell wall digest from S14a competed with sensitive yeast cells for 35S-labeled toxin binding and reduced toxin-dependent killing of a sensitive strain . Wall digest from kre1-1 competed only weakly for toxin binding with sensitive cells and caused little reduction of toxin-dependent killing . Although the abundant (1.1 x 10(7) per cell) receptor appeared necessary for toxin action, as few as 2.8 x 10(4) toxin molecules were necessary to kill a sensitive cell of S14a . The kinetics killing of S14a suggested that some component was saturated with toxin at a concentration 50-fold lower than that needed to saturate the wall receptor.

J Bacteriol, 1979 Dec, 140(3), 874 - 80
Regulation of activity and synthesis of N-acetylglutamate synthase from Saccharomyces cerevisiae; Wipe B et al.; Feedback inhibition of N-acetylgutamate synthase in a particulate fraction from Saccharomyces cerevisiae by L-arginine was synergistically enhanced by N-actylglutamate, whereas coenzyme A let to an additive enhancement of arginine inhibition . N-acetylglutamate synthase was not inhibited by polyamines, nor was the enzyme inactivated by incubation in the presence of coenzyme A and zinc ions . Evidence was obtained for the involvement of at least three different regulatory mechanisms in the expression of N-acetylglutamate synthase: arginine-specific repression, glucose repression and general amino acid control . The combined action of these control mechanisms led to a 90-fold variation in the specific activity of the enzyme.

Cell, 1979 Dec, 18(4), 1247 - 59
Isolation of cloned DNA sequences containing ribosomal protein genes from Saccharomyces cerevisiae; Woolford JL Jr et al.; Yeast mRNA enriched for ribosomal protein mRNA was obtained by isolating poly(A)+ small mRNA from small polysomes . A comparison of cell-free translation of this small mRNA and total mRNA, and electrophoresis of the products on two-dimensional gels which resolve most yeast ribosomal proteins, demonstrated that a 5-10 fold enrichment for ribosomal protein mRNA was obtained . One hundred different recombinant DNA molecules possibly containing ribosomal protein genes were selected by differential colony hybridization of this enriched mRNA and unfractionated mRNA to a bank of yeast pMB9 hybrid plasmids . After screening twenty-five of these candidates, five different clones were found which contain yeast ribosomal protein gene sequences . The yeast mRNAs complementary to these five plasmids code for 35S-methionine-labeled polypeptides which co-migrate on two-dimensional gels with yeast ribosomal proteins . Consistent with previous studies on ribosomal protein mRNAs, the amounts of mRNA complementary to three of these cloned genes are controlled by the RNA2 locus . Although two of the five clones contain more than one yeast gene, none contain more than one identifiable ribosomal protein gene . Thus there is no evidence for "tight" linkage of yeast ribosomal protein genes . Two of the cloned ribosomal protein genes are single-copy genes, whereas two other cloned sequences contain two different copies of the same ribosomal protein gene . The fifth plasmid contains sequences which are repeated in the yeast genome, but it is not known whether any or all of the ribosomal protein gene on this clone contains repetitive DNA.

J Bacteriol, 1979 Dec, 140(3), 971 - 9
Allantoate transport in Saccharomyces cerevisiae; Turoscy V et al.; Allantoate uptake appears to be mediated by an energy-dependent active transport system with an apparent Michaelis constant of about 50 microM . Cells were able to accumulate allantoate to greater than 3,000 times the extracellular concentration . The rate of accumulation was maximum at pH 5.7 to 5.8 . The energy source for allantoate uptake is probably different from that for uptake of the other allantoin pathway intermediates . The latter systems are inhibited by arsenate, fluoride, dinitrophenol, and carboxyl cyanide-m-chlorophenyl hydrazone, whereas allantoate accumulation was sensitive to only dinitrophenol and carboxyl cyanide-m-chlorophenyl hydrazone . Efflux of preloaded allanotate did not occur at detectable levels . However, exchange of intra- and extracellular allantoate was found to occur very slowly . The latter two characteristics are shared with the allantoin uptake system and may result from the sequestering of intracellular allantoate within the cell vacuole . During the course of these studies, we found that, contrary to earlier reports, the reaction catalyzed by allantoinase is freely reversible.

Nature, 1979 Nov 29, 282(5738), 478 - 3
Transposable mating type genes in Saccharomyces cerevisiae; Hicks J et al.; A functional copy of the alpha mating type gene of Saccharomyces cerevisiae has been cloned by transformation in yeast . Using the Southern Blotting procedure it has been shown that three distinct genetic loci implicated in mating type interconversion (HML, HMR and MAT) contain sequences homologous to the clone fragment . The restriction fragment associated with each locus exhibits a characteristic size which can be correlated with the mating type allele present at that locus . The characteristic size difference between the a and alpha genetic elements made it possible to demonstrate that the homothallic interconversion of mating types in this yeast occurs by DNA rearrangement as proposed in the 'cassette hypothesis'.

Biochim Biophys Acta, 1979 Nov 21, 575(2), 204 - 14
Triaglycerol metabolism in Saccharomyces cerevisiae . Relation to phospholipid synthesis; Taylor FR et al.; The acylglycerol content of Saccharomyces cerevisiae has been examined during cellular growth . The cells maintained a constant amount of phospholipid and diacylglycerol throughout growth . Triacylglycerol content fell in the early exponential phase of growth and then increased sharply upon entry of the culture into the stationary growth phase . Pulse-chase experiments with {1-14C}oleic acid and {2-3H}- and {1-14C}glycerol indicated that the triacylglycerol molecule was utilized for phospholipid synthesis in early exponential phase probably through a diacylglycerol intermediate . A substantial turnover of phospholipid during growth was also apparent . No role for the triacylglycerol could be found in regulating the fatty acid species of the phospholipid nor in the storage of fatty acid for energy metabolism.

C R Seances Acad Sci D, 1979 Nov 5, 289(11), 773 - 5
{Expression of a bacterial gene, cloned in the yeast, Saccharomyces cerevisiae}; Panthier JC et al.; Vectors allowing cloning of foreign D.N.A . in the yeast Saccharomyces cerevisiae have been recently described . We have introduced in this yeast the lac Z gene of the bacteria Escherichia coli . An active beta-galactosidase, which is absent in the recipient strain, has been detected in transformed yeast . We thus conclude that the bacterial lac Z gene is expressed in yeast . We further showed that the enzyme found in the transformed yeast is identical to the bacterial enzyme with respect to size and immunological criteria.

Pol J Pharmacol Pharm, 1979 Nov-Dec, 31(6), 683 - 7
The influence of the composition of the selective medium on convertogenic activity of ethyl methanesulfonate in Saccharomyces cerevisiae D4; Jaszczuk E et al.; The frequency of prototrophic recombinants produced by mitotic gene conversion at the trp5 and ade2 loci were observed using the plate test . The yeast cells were exposed in the concentration gradient of ethyl methanesulphonate--EMS (10 microliter/plate) . Selective media with addition of a small amount of tryptophan (for the selection of the convertants trp+) or adenine (for the selection of the convertants ade+) were used . The use of medium with addition of tryptophan or adenine considerably increased the sensitivity of the plate method as compared with the use of the medium deficient in either tryptophan or adenine . The above results suggest possible usefulness of testing for mutagenic activity various chemical using growing cells of yeast.

Mol Gen Genet, 1979 Nov, 176(3), 427 - 31
Isolation and characterization of further cis- and trans-acting regulatory elements involved in the synthesis of glucose-repressible alcohol dehydrogenase (ADHII) in Saccharomyces cerevisiae; Ciriacy M; Starting with yeast cells lacking the constitutive alcohol dehydrogenase activity (ADHI), mutants with partially glucose-insensitive formation of ADHII were isolated . Genetic analysis showed that four mutants (designated ADR3c) were linked to the ADHII-structural gene, ADR2, and were cis-dominant . On derepression, two of them produced elevated ADHII-levels, indicating a promotor function of the altered controlling site . The other ADR3c-mutant alleles affected the ADHII-subunit association in diploids carrying two electrophoretically distinct alleles of the structural gene ADR2 . Twelve semidominant constitutive mutants could be attributed to gene ADR1 (ADR1c-alleles) previously identified by recessive mutants with blocked derepression . This suggested a positive regulatory role of the ADR1 gene product on the expression of the ADHII-structural gene . A pleiotropic mutation ccr1 (Ciriacy, 1977) was epistatic over glucose-resistant ADHII-formation caused by ADR1c-alleles . From this it was concluded that CCR1 specifies for a product co-activating the structural gene or modifying the ADR1-gene product . A further regulatory element (gene designation ADR4) not linked to the structural gene could be identified upon isolation of recessive constitutive mutants adr4 from a ccr1 ADR1c-double mutant.

Mol Gen Genet, 1979 Nov, 176(3), 411 - 5
Sporulation of mitochondrial respiratory deficient mit- mutants of Saccharomyces cerevisiae; Pratje E et al.; The role of mitochondrial protein synthesis, electron transport, and four specific mitochondrial gene products on sporulation were studied in respiratory deficient mit- mutants . These mutants were isolated in an op 1 strain and localized on the mitochondrial genome by petite deletion mapping . All 153 mutations studied could be assigned to the four mitochondrial regions OXI1, OXI2, OXI3 and COB, known to affect cytochrome c oxidase and cytochrome b . The specific loss of one mitochondrially translated polypeptide was found in some mutants of each locus: OXI1--cytochrome c oxidase subunit 2, OXI2--subunit 3, OXI3--subunit 1, and COB--cytochrome b . The ability of diploid mit- mutants to sporulate was systematically investigated . About one third of the mutants, representing three loci, were incapable of forming spores . All other cultures produced either respiratory competent mit+ tetrads, both mit+ and mit- tetrads, or only mit- tetrads . Mutants forming mit- tetrads mapped in all four loci . These results demonstrate that in contrast to petite mutants some mit- mutants have retained the ability to perform meiosis and sporulation.

Genetika, 1979 Nov, 15(11), 1944 - 52
{Genetic effects of N-nitroso-N-methylurea on Saccharomyces cerevisiae yeasts . I . The influence of radiosensitivity mutations on lethal and recombinogenic effects}; Iadgarov KhT et al.; Effect of mutations rad2 and rad54 in homozygous state on survival, mitotic segregation and crossing-over induced by NMU in yeast was studied . Mutation rad2 did not influence on these effects of NMU . The mutation rad54 increased sensitivity to the lethal effect, the frequencies of NMU-induced segregation and crossing-over were decreased in the strain rad54 rad54 . The recombinogenic effect of NMU on yeast was lower than under the action of UV and gamma rays.

J Bacteriol, 1979 Nov, 140(2), 504 - 7
Genetics and physiology of proline utilization in Saccharomyces cerevisiae: mutation causing constitutive enzyme expression; Brandriss MC et al.; A mutation resulting in inducer-independent expression of the proline-degradative enzymes was isolated in the yeast Saccharomyces cerevisiae . Strains carrying the mutation, put3, are partially constitutive for proline oxidase and delta 1-pyrroline-5-carboxylate dehydrogenase when grown on a medium lacking proline and are hyperinducible for both enzyme activities when grown on a proline-containing medium . put3 segregates as a single nuclear gene, is not linked to either of the presumed structural genes for proline oxidase and delta 1-pyrroline-5-carboxylate dehydrogenase, and does not affect proline transport . When heterozygous in diploid strains, put3 behaves neither fully dominant nor fully recessive . Endogenous induction by proline has been eliminated as a cause of the inducer-independent enzyme expression in the put3 mutant and the mutation is believed to be in a regulatory component of the proline-degradative pathway.

J Bacteriol, 1979 Nov, 140(2), 498 - 503
Genetics and physiology of proline utilization in Saccharomyces cerevisiae: enzyme induction by proline; Brandriss MC et al.; Proline is converted to glutamate in the yeast Saccharomyces cerevisiae by the sequential action of two enzymes, proline oxidase and delta 1-pyrroline-5-carboxylate (P5C) dehydrogenase . The levels of these enzymes appear to be controlled by the amount of proline in the cell . The capacity to transport proline is greatest when the cell is grown on poor nitrogen sources, such as proline or urea . Mutants have been isolated which can no longer utilize proline as the sole source of nitrogen . Mutants in put1 are deficient in proline oxidase, and those in put2 lack P5C dehydrogenase . The put1 and put2 mutations are recessive, segregate 2:2 in tetrads, and appear to be unlinked to one another . Proline induces both proline oxidase and P5C dehydrogenase . The arginine-degradative pathway intersects the proline-degradative pathway at P5C . The P5C formed from the breakdown of arginine or ornithine can induce both proline-degradative enzymes by virtue of its conversion to proline.

Biotechnol Bioeng, 1979 Nov, 21(11), 1929 - 61
Alternate method of calculating the free-energy change accompanying the growth of saccharomyces cerevisiae (Hansen) on three substrates; Battley EH; A method is described for determining the free energy of formation of the cells of Saccharomyces cerevisiae (Hansen) that are formed as the result of anaerobic growth on glucose, and aerobic growth on glucose and ethanol . The method is based on the direct relationship that exists between the enthalpy changes and the free-energy changes that accompany the oxidation of 1 g cellular material formed during these growth reactions and the degree of reduction of the same material . When the results of these calculations are used together with the free energies of formation of the reactants and of other products of a given growth reaction, it becomes possible to calculate the free-energy change accompanying this reaction . These free-energy changes are in excellent agreement with those calculated by another method based on the hypothesis that the free-energy change accompanying the conversion of the substrate plus other reactants into cellular material plus other products is equal to zero.

Eur J Biochem, 1979 Nov, 101(2), 455 - 60
Inactivation of gluconeogenic enzymes in glycolytic mutants of Saccharomyces cerevisiae; Gancedo JM et al.; Yeast mutants blocked at different steps of the glycolytic pathways have been used to study the inactivation of several gluconeogenic enzymes upon addition of sugars . While phosphorylation of the sugars appears a requisite for the inactivation of fructose 1,6-bisphosphatase and phosphoenol-pyruvate carboxykinase, malate dehydrogenase is inactivated by fructose in mutants lacking hexokinase . The normal inactivation elicited by glucose in a mutant lacking phosphofructokinase indicates that the process does not require metabolism of the sugar beyond hexose monophosphates . A possible role for ATP in the inactivation process is suggested.

Biochim Biophys Acta, 1979 Oct 26, 575(1), 148 - 55
Characterization of sterol-ester synthetase in Saccharomyces cerevisiae; Taketani S et al.; Cell-free extracts of Saccharomyces cerevisiae grown under aerobic as well as semi-anaerobic conditions were found to catalyze the synthesis of fatty acid ester of sterol from cholesterol, fatty acid, ATP and CoA, or from cholesterol and fatty acyl-CoA . This result indicates that the enzyme involved in the formation of the ester is acyl-CoA:sterol O-acyltransferase (EC 2.3.1.26) . The enzyme had a broad substrate specificity for sterols and acyl-CoAs . The enzyme levels in the cells grown under aerobic and semi-anaerobic conditions were almost equal . The enzyme was located in the microsomal fraction of the aerobically grown cells.

Biochemistry, 1979 Oct 16, 18(21), 4487 - 99
Phosphorus-31 nuclear magnetic resonance studies of wild-type and glycolytic pathway mutants of Saccharomyces cerevisiae; Navon G et al.; High-resolution phosphorus-31 nuclear magnetic resonance (31P NMR) spectra of wild-type and mutant strains of Saccharomyces cerevisiae were observed at a frequency of 145.7 MHz . Levels of various phosphorus metabolites were investigated upon addition of glucose under both aerobic and anaerobic conditions . Three mutant strains were isolated and their biochemical defects characterized: pfk lacked phosphofructokinase activity; pgi lacked phosphoglucose isomerase activity; and cif had no glucose catabolite repression of the fructose bisphosphatase activity . Each mutant strain was found to accumulate characteristic sugar phosphates when glucose was added to the cell suspension . In the case of the phosphofructokinase deficient mutant, the appearance of a pentose shunt metabolite was observed . 31P NMR peak assignments were made by a pH titration of the acid extract of the cells . Separate signals for terminal, penultimate, and central phosphorus atoms in intracellular polyphosphates allowed the estimation of their average molecular weight . Signals for glycero(3)phosphochline, glycero(3)phosphoserine, and glycero(3) phosphoethanolamine as well as three types of nucleotide diphosphate sugars could be observed . The intracellular pH in resting and anaerobic cells was in the range 6.5--6.8 and the level of adenosine 5'-triphosphate (ATP) low . Upon introduction of oxygen, the ATP level increased considerably and the intracellular pH reached a value of pH 7.2--7.3, irrespective of the external medium pH, indicating active proton transport in these cells . A new peak representing the inorganic phosphate of one of the cellular organelles, whose pH differed from the cytoplasmic pH, could be detected under appropriate conditions.

J Biol Chem, 1979 Oct 10, 254(19), 9839 - 45
The primary structure of a glyceraldehyde-3-phosphate dehydrogenase gene from Saccharomyces cerevisiae; Holland JP et al.; The complete nucleotide sequence of the coding, as well as the flanking noncoding regions, of a yeast glyceraldehyde-3-phosphate dehydrogenase gene was determined . Both the 5' and 3' noncoding sequences are extremely AT-rich and regions of partial dyad symmetry are present immediately adjacent to the 5' and 3' ends of the translated portion of the gene . The sequence AAUAAA is present in the 3' noncoding region of this gene and is a part of an extensive region of dyad symmetry which is structurally related to the 3'-terminal portion of both procaryotic mRNAs, as well as some eukaryotic mRNAs . The coding region of this gene does not contain intervening sequences . Establishment of the primary structure of this glyceraldehyde-3-phosphate dehydrogenase gene provides a basis for further studies involving in vitro mutation of the gene and subsequent analysis of gene expression in vivo.

Mol Gen Genet, 1979 Oct 2, 176(1), 37 - 9
Nalidixic acid causes a transient G1 arrest in the yeast Saccharomyces cerevisiae; Singer RA et al.; The addition of nalidixic acid to growing cells of the yeast Saccharomyces cerevisiae resulted in a transient depression in the rate of ribosomal precursor RNA production and a transient arrest of cells in G1 . Protein synthesis rates were less affected . Lower concentrations of nalidixic acid also affected RNA synthesis and progression through G1 but had no effect on protein synthesis rates . We suggest that nalidixic acid has a primary effect on RNA synthesis leading to a G1 arrest.

Appl Environ Microbiol, 1979 Oct, 38(4), 751 - 3
Phosphate uptake in Saccharomyces cerevisiae Hansen wild type and phenotypes exposed to space flight irradiation; Berry D et al.; Rates of phosphate uptake were approximately twice as great for Saccharomyces cerevisiae single-cell phenotypic isolates exposed to space parameters as for the wild-type ground control . Quantitative determination of 32P was performed by liquid scintillation spectrometry utilizing Cerenkov radiation counting techniques.

Can J Microbiol, 1979 Oct, 25(10), 1139 - 44
The effect of pantothenate on sulfate metabolism and sulfur isotope fractionation by Saccharomyces cerevisiae; McCready RG et al.; Growth of Saccharomyces cerevisiae in minimal salts-glucose-SO4(2-) medium with varying concentrations of pantothenate (0-1000 microgram/L) produced changes in the cellular lipid content and in the ratio of saturated to unsaturated fatty acids . Substantial differences in SO4(2-) diffusion were also observed with changes in pantothenate concentration . During sulfate reduction, the delta 34S value of the evolved sulfide varied with the pantothenate concentration ranging from -31% in the absence of pantothenate to 0% at 400-1000 microgram/L pantothenate . The isotope selectivity is related to the effect of pantothenate concentration on cellular metabolism.

Mol Gen Genet, 1979 Oct 1, 175(3), 313 - 23
A cold-sensitive mutant of Saccharomyces cerevisiae defective in ribosome processing; Ursic D et al.; Cold-sensitive mutants of Saccharomyces cerevisiae isolated by tritium suicide were screened for defects in ribosome biosynthesis . The biochemical defects of mutant dip-1 (defective in processing) were characterized; it is defective in ribosome biosynthesis at the level of production of the primary 35S transcript . At restrictive conditions mutant dip-1 accumulates abnormal rRNA in addition to wild-type rRNA . In the mutant the first observable transcription product was a 14SRNA species which had sequence homologies to 18S rDNA and was the major rRNA component of the 40S ribosomal subunit . In addition, the ribonucleoprotein particles of dip-1 harbored RNA molecules with homologies to yeast rDNA which comprises the spacer region between 18S and 25S rDNA cistrons . Possible causes for the defective production of rRNA and its assembly into subunits are discussed.

Mutat Res, 1979 Oct, 68(2), 133 - 48
Genetic effect of 3-carbethoxypsoralen, angelicin, psoralen and 8-methoxypsoralen plus 365-nm irradiation in Saccharomyces cerevisiae: induction of reversions, mitotic crossing-over, gene conversion and cytoplasmic "petite" mutations; Averbeck D et al.; The genetic effects of two mono-functional photosensitizing furocoumarins, 3-carbethoxypsoralen (3-CPs) and angelicin, were compared with those of two bi-functional furocoumarins, 8-methoxypsoralen and psoralen in Saccharomyces cerevisiae . A drug concentration of 5 X 10(-5) M plus various doses of 365-nm irradiation at a dose rate of 1.2 kJ m-2 min-1 were used . Per dose of 365-nm irradiation, the frequency of induced nuclear events such as gene mutation and mitotic recombination (conversion and crossing-over) is higher for the bi-functional than for the mono-functional compounds . The higher efficiency of the bi-functional furocoumarins is also evident when the frequency of mutants is expressed as a function of survival . However, the photo-addition of the 4 furocoumarins studied leads to the same response for the induction of recombinational events per viable cell . Amongst genetically altered colonies induced in the diploid strains D5 and D7, the colonies corresponding to the induction of crossing-over are effectively produced by bi-functional furocoumarins, but are rare (D7) or even absent (D5) after treatment with monofunctional furocoumarins . This suggests a certain specificity of genetic alterations produced by the bi-functional agents . 3-CPs is the most effective inducer on the cytoplasmic "petite" mutation in stationary phase cells per unit irradiation dose or per viable cell.

Gene, 1979 Oct, 7(2), 141 - 52
Replication in Saccharomyces cerevisiae of plasmid pBR313 carrying DNA from the yeast trpl region; Kingsman AJ et al.; Plasmid pBR313 carrying a 1.4 kb EcoRI fragment from the yeast TRP1 region (designated pLC544) is capable of transforming yeast trp1 mutants to Trp+ at high frequency (10(3)--10(4) transformants/micrograms DNA) . Transformation can be achieved either by using purified plasmid DNA or by fusion of yeast spheroplasts with partially lysed Escherichia coli {pLC544} protoplast preparations . The Trp+ yeast transformants are highly unstable, segregating Trp- cells at frequencies of 0.18 per cell per generation (haploids) and 0.056 per cell per generation (diploids) in media containing tryptophan . Plasmid pLC544 replicates autonomously in the nucleus of yeast cells and segregation of Trp-cells is associated with the complete loss of plasmid sequences . In genetic crosses, pLC544 is randomly assorted during meiosis and is carried unchanged through the mating process into haploid recombinants.

Proc Natl Acad Sci U S A, 1979 Oct, 76(10), 5222 - 5
A response of protein synthesis to temperature shift in the yeast Saccharomyces cerevisiae; Miller MJ et al.; When Saccharomyces cerevisiae are subjected to a sudden increase in temperature (22 degrees C to 37 degrees C) they undergo extensive and, in some cases, extreme alterations in their rates of synthesizing individual polypeptides . These changes were monitored by pulse-labeling cells with {35S}methionine and separating the total soluble proteins by two-dimensional gel electrophoresis . Incorporation of 35S into individual proteins was measured by a computer-coupled autoradiogram-scanning method . The rates of synthesis of most proteins are transiently changed; 10-fold or greater induction or respression is common . This temperature response has also been studied in a mutant strain that is temperature sensitive for the nucleus-to-cytoplasm transport of RNA . In this mutant, not only the induction, but also a part of the repression in response to temperature upshift is largely inhibited . Conceivable mechanisms are discussed.

J Bacteriol, 1979 Oct, 140(1), 289 - 93
Scanning electron microscope study of Saccharomyces cerevisiae spheroplast formation; Pringle AT et al.; A suspension of Saccharomyces cerevisiae NCY366 in buffered 1.2 M sorbitol containing Zymolyase-5000 (a beta-glucanase-containing preparation/showed maximum osmotic sensitivity after 30 min of incubation at 30 degrees C . A scanning electron microscope study of spheroplast formation, using a very high resolution (4-nm) machine, revealed several new morphological features . The surface of the plug in bud scars on intact cells appeared warty . The wall, which assumed a beady appearance as digestion proceded, ultimately sloughed off to reveal the furrowed surface of the plasma membrane . Bud scars were resistant to digestion and . as incubation proceeded, they became surrounded by an outer annulus, which may be the seconary septum . Wall material was completely removed from the majority of cells only after 60 min of digestion . The surface of spheroplasts was studded with particles, about 25 to 30 nm in diameter . Many spheroplasts had a single large indentation, which may be in that part of the plasma membrane originally underlying the birth scar.

Genetics, 1979 Sep, 93(1), 81 - 103
The fate of mitochondrial loci in rho minus mutants induced by ultraviolet irradiation of Saccharomyces cerevisiae: effects of different post-irradiation treatments; Heude M et al.; Three main features regarding the loss of mitochondrial genetic markers among rho- mutants induced by ultraviolet irradiation are reported: (a) the frequency of loss of six loci examined increases with UV dose; (b) preferential loss of one region of the mitochondrial genome observed in spontaneous rho- mutants is enhanced by UV; and (c) the loss of each marker results from large deletions . Marker loss in rho- mutants was also investigated under conditions that modulate rho- induction . Liquid holding of irradiated exponential or stationary phase cells, as well as a split-dose regime applied to stationary phase cells, results in rho- mutants in which the loss of markers is correlated with rho- induction: the more sensitive the cells are to rho- induction, the more frequent are the marker losses among rho- clones derived from these cells . This correlation is not found in exponential-phase cells submitted to a split-dose treatment, suggesting that a different mechanism is involved in the latter case . It is known that UV-induced pyrimidine dimers are not excised in a controlled manner in mitochondrial DNA . However, our studies indicate that an accurate repair mechanism (of the recombinational type ?) can lead to the restoration of mitochondrial genetic information in growing cells.

Appl Environ Microbiol, 1979 Sep, 38(3), 461 - 5
Respiration and viability of thermally injured Saccharomyces cerevisiae; Graumlich TR et al.; Resting cells of Saccharomyces cerevisiae Y25 were heated at 56 degrees C for 0 to 2 min . Respiratory activity of the cells reflected the severity of the heat stress . The endogenous respiration was approximately 50 microliter of O2/mg per h for cells heated for 2 min at 56 degrees C as compared with 2 microliter of O2/mg per h for nonheated cells . There was a distinct decrease in respiration after 1 to 3 h, and after 20 h the respiration rate of heated cells was less than that of nonheated cells . Along with increased rates of endogenous respiration, respiratory quotients of cells were altered after heat stress . Addition of 2,4-dinitrophenol stimulated O2 (uptake) in nonheated cells but decreased O2 (uptake) of heated cells . Due to the high rate of endogenous respiration, addition of glucose resulted in no substantial change in the rate of respiration of heated cells . However, addition of glucose prolonged the presence of the high rates of respiration observed in heated cells.

Proc Natl Acad Sci U S A, 1979 Sep, 76(9), 4589 - 92
Enhanced mitotic recombination in a ligase-defective mutant of the yeast Saccharomyces cerevisiae; Game JC et al.; The temperature-sensitive Saccharomyces cerevisiae cell cycle mutant cdc9 is defective in DNA ligase, and the DNA synthesized at the restrictive temperature contains many single-strand breaks . We find that holding a diploid homozygous for cdc9 at the restrictive temperature and then plating cells at the permissive temperature gives rise to increased intragenic and intergenic recombination . In the latter case, recombinants signaled by the ade2 locus rise to about 4% of the survivors after 6 hr of incubation at the restrictive temperature . We propose that the single-strand breaks left in DNA synthesized at the restrictive temperature may lead to recombination.

Proc Natl Acad Sci U S A, 1979 Sep, 76(9), 4539 - 43
Activation of mating type genes by transposition in Saccharomyces cerevisiae; Klar AJ et al.; Yeast Saccharomyces cerevisiae may express an a or alpha mating type . These cells types may be interconverted as a consequence of heritable genetic alteractions at the mating type locus (MAT) . According to the more general controlling element model {Oshima, U . & Takano, I . (1971) Genetics 67, 327--335} and the specific cassette model {Hicks, J., Strathern, J . & Herskowitz, I . (1977) in DNA Insertion Elements, Plasmids and Episomes, eds . Bukhari, A . I., Shapiro, J.A . & Adhya, S . L.(Cold Spring Harbor Laboratory, Cold Spring Harbor, NY), pp . 457--462}, the regulatory information required for switching the MAT locus exists at two other loosely linked loci, HMa and HMalpha . Specifically, the HMa and HMalpha loci are proposed to carry silent alpha and silent a genes, respectively . According to these models, switching occurs when a replica of a silent gene replaces the resident information at the mating type locus and is thereby expressed . These models predict that mutations at the silent ("storage") loci would generate defective MAT loci subsequent to the switching process . Therefore, the behavior of HMalpha mutants during the mating type interconversion was investigated . The results demonstrate that defective MATa alleles are generated by switching the MATalpha locus in HMalpha mutants . Thus, the genetic information from HMalpha is transposed to the mating type locus . These results provide genetic evidence in support of these models.

J Bacteriol, 1979 Sep, 139(3), 917 - 23
Oxalurate transport in Saccharomyces cerevisiae; Cooper TG et al.; Oxalurate, the gratuitous inducer of the allantoin degradative enzymes, was taken into the cell by an energy-dependent active transport system with an apparent Km of 1.2 mM . Efflux of previously accumulated oxalurate was rapid, with a half-life of about 2 min . The oxalurate uptake system appears to be both constitutively produced and insensitive to nitrogen catabolite repression . The latter observations suggest that failure of oxalurate to bring about induction of allophanate hydrolase in cultures growing under repressive conditions does not result from inducer exclusion, but rather from repression of dur1,2 gene expression.

J Bacteriol, 1979 Sep, 139(3), 866 - 76
Metabolic suppressors of trimethoprim and ultraviolet light sensitivities of Saccharomyces cerevisiae rad6 mutants; Lawrence CW et al.; Dominant mutations at two newly identified loci, designated SRS1 and SRS2, that metabolically suppress the trimethoprim sensitivity of rad6 and rad18 strains, have been isolated from trimethoprim-resistant mutants arising spontaneously in rad6-1 rad18-2 strains of the yeast Saccharomyces cerevisiae . The SRS2 mutations also efficiently suppress the ultraviolet light sensitivity of the parent strains . They do not, however, suppress their sensitivity to ionizing radiation or their deficiency with respect to induced mutagenesis and sporulation . Such observations support the hypothesis that RAD6-dependent activities can be separated into two functionally distinct groups: a group of error-free repair activities that are responsible for a large amount of the radiation resistance of wild-type strains and also for their resistance to trimethoprim, and a group of error-prone activities that are responsible for induced mutagenesis and are also important in sporulation, but which account at best for only a very small amount of wild-type recovery.

Orig Life, 1979 Sep, 9(4), 329 - 34
Oxygen as a factor in eukaryote evolution: some effects of low levels of oxygen on Saccharomyces cerevisiae; Jahnke L et al.; A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03% (v/v) oxygen . Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth, was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth, was maximally active at much higher oxygen levels (greater than 1%) . Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.

Biochim Biophys Acta, 1979 Aug 22, 586(2), 258 - 65
Catabolite inactivation of phosphoenolpyruvate carboxykinase in spheroplasts from Saccharomyces cerevisiae; Matern H; Catabolite inactivation of phosphoenolpyruvate carboxykinase was studied in yeast spheroplasts using 0.9 M mannitol or 0.6 M potassium chloride as the osmotic support . In the presence of potassium chloride the rate of catabolite inactivation was nearly the same as that occurring in intact yeast cells under different conditions of incubation . However, in the presence of mannitol, catabolite inactivation in spheroplasts was prevented . The mannitol inhibition of catabolite inactivation was released by addition of ammonium or phosphate ions . At a concentration of 0.3 M ammonium or 0.06 M phosphate ions, the maximum rate of catabolite inactivation in spheroplasts suspended in mannitol was achieved and was comparable with that observed in spheroplasts incubated in 0.6 M potassium chloride as the osmotic stabilizer . Sodium sulfate (0.04 and 0.4 M) or potassium chloride (0.06 and 0.6 M) did not release the mannitol inhibition of catabolite inactivation in spheroplasts . In intact yeast cells, 0.9 M mannitol, 0.08 M ammonium or 0.1 M phosphate ions did not influence the rate of catabolite inactivation . The nature of the effect of mannitol, ammonium and phosphate ions on catabolite inactivation in yeast spheroplasts is discussed.

J Biol Chem, 1979 Aug 10, 254(15), 7427 - 33
The product of the his4 gene cluster in Saccharomyces cerevisiae . A trifunctional polypeptide; Keesey JK Jr et al.; The his4 region of yeast encodes the information for the third (phosphoribosyl-AMP cyclohydrolase), second (phosphoribosyl-ATP pyrophosphohydrolase), and tenth (histidinol dehydrogenase) steps in the histidine biosynthetic pathway . These three activities co-purify with a single protein which has a subunit molecular weight of 95,000 (95,000 protein), as determined by electrophoresis on polyacrylamide gels in the presence of sodium dodecyl sulfate . Extracts of yeast strains which carry nonsense or deletion mutations in various portions of the his4 region, purified in parallel by affinity chromatography on AMP-agarose columns, were examined on sodium dodecyl sulfate-polyacrylamide gel electrophoresis slabs . All such mutant extracts examined were found to lack the 95,000 protein found in a strain carrying a wild type his4 allele . The presence of a protease inhibitor, phenylmethylsulfonyl fluoride, during the purification of the trifunctional enzyme prevented the degradation of the 95,000 protein to polypeptides of lower molecular weight . Monospecific antibody prepared against the 95,000 protein removed all three of the activities specified by his4 from solution; active 95,000 protein was recovered in the resuspended immunoprecipitates . All this evidence shows that the product of the his4 region is a trifunctional, 95,000-dalton protein . Preliminary evidence from two-dimensional gel electrophoresis, NH2-terminal analysis, and gel filtration column chromatography indicates that the native trifunctional enzyme is a dimer of identical 95,000-dalton subunits.

Lipids, 1979 Aug, 14(8), 741 - 7
The effects of the hypocholesteremic compound 3 beta-(beta-dimethylaminoethoxy)-androst-5-en-17-one on the sterol and steryl ester composition of Saccharomyces cerevisiae; Field RB et al.; When yeast was grown in the presence of 10(-4) M 3 beta-(beta-dimethylaminoethoxy)-androst-5-en-17-one (DMAE-DHA), the compound 2,3;22,23-dioxidosqualene (DOS) accumulated . Total free sterol was reduced by about 30%, whereas almost no steryl esters were found . The same drug at lower concentration (3 x 10(-6) M) caused a slight increase in steryl ester production, and a 24% reduction in free sterol content . The marked accumulation of ergostra-5,7,22,24(28)-tetraen-3 beta-ol with 3 x 10(-6) M DMAE-DHA indicated that the C24-28 reductase is especially sensitive to the action of the drug.

Can J Microbiol, 1979 Aug, 25(8), 888 - 95
Changes in electrophoretic mobility and lytic enzyme activity associated with development of flocculating ability in Saccharomyces cerevisiae; Beavan MJ et al.; Cells from stationary-phase cultures of two strains of Saccharomyces cerevisiae (3 and 20) failed to flocculate when grown in a complex or a chemically defined medium, while those of two other strains (11 and 13) flocculated when grown in either medium . Strain 30 flocculated when grown in complex but not defined medium and harvested from stationary-phase cultures . pH-electrophoretic mobility measurements on all five strains showed that mobility attributable to carboxyl groups usually increased as cultures progressed from the exponential to the stationary phase, while that caused by phosphate groups tended to decline . Acquisition of flocculating ability was accompanied in strains 11 and 30 by a slight increase in amidase activity, and greater increases compared with nonflocculent populations in activities of leucine aminopeptidase . alpha-mannosidase, and proteinase C . Activities of proteinases A and B showed no correlation with acquisition of flocculating ability.

Mol Gen Genet, 1979 Aug, 175(1), 45 - 52
Inheritance of multiple drug resistance in Saccharomyces cerevisiae: linkage to leu1 and analyses of 2 micron DNA in partial revertants; Saunders GW et al.; The inheritance and phenotype of multiple drug resistance in independent multiple drug resistant mutants, two isolated in this laboratory (GR359 and 2-20), and two (DRI 9/T7 and DRI 9/T8) reported by Guerineau et al . (Biochem . Biophys . Res . Commun . 61,462), was investigated . Comparison of resistance to 12 selected drugs showed that the resistance phenotypes of all mutants were similar, although some differences in levels of resistance of each mutant was observed with certain drugs . Mapping of the resistance loci in GR359 and 2-20 revealed tight linkage of both resistance genes to the centromere linked gene leul . 2 micron DNA was analysed by hybridization of 2 micron RNA to EcoRI fragments of a total DNA extract . Eight partial revertants of 2-20, which had been chosen as having a phenotype similar to the 2 micron DNA deficient {cir degrees} isolate DRI 9/T7, revealed the presence of 2 micron DNA . The lack of detectable 2 micron DNA in DRI 9/T7 was confirmed.

Mol Gen Genet, 1979 Aug, 175(1), 111 - 2
Low ribonuclease activity in cellular lysates of osmotic sensitive Saccharomyces cerevisiae mutants; Venkov PV; Cellular lysates with very low total ribonuclease activities are obtained by lysis of Saccharomyces cerevisiae VY1160 osmotic sensitive mutant cells in 1% sorbitol solution . These lysates could be used for isolation of intact polysomes and messenger RNA molecules, or for studying of specific ribonucleases.

Environ Health Perspect, 1979 Aug, 31, 97 - 111
Detection of mitotic and meiotic aneuploidy in the yeast Saccharomyces cerevisiae; Parry JM et al.; A number of genetic systems are described which involve the use of the yeast Saccharomyces cerevisiae . The systems may be used to detect the production of aneuploid cells produced during both mitotic and meiotic cell division in the presence of genetically active chemicals . During mitotic cell division, monosomic colonies (2n - 1) may be detected by plating upon selective medium . Increases in such monosomic colonies are produced by exposure of cells to a number of chemical mutagens such as ethyl methane-sulfonate and mitomycin C . More importantly, monosomic colonies are also induced by nonmutagens such as sulfacetamide and saccharin, which suggests that such chemicals are capable of inducing aneuploidy (aneugenic) in the absence of mutagenic activity . Genetic analysis of aneuploid colonies produced on nonselective medium indicate that at least a proportion of the monosomic colonies were the result of mitotic nondisjunction . During meiotic cell division, disomic cells (n + 1) produced by chromosome nondisjunction may be detected by plating on selective media . The frequency of disomic cells has been shown to increase after exposure to p-fluorophenylalanine.

Mutat Res, 1979 Aug, 62(1), 27 - 33
Effect of X-irradiation on frameshift and missense mutations in Saccharomyces cerevisiae; Panzeri L et al.; In cell populations of Saccharomyces cerevisiae homogeneous for sensitivity to X-irradiation, induction of base insertions/deletions and base substitutions was quantitatively analyzed in a reversion system . The repair mechanisms phenotypically unexpressed in the sensitive cell fraction and fully operating in resistant cells did not affect point mutations of either type.

J Bacteriol, 1979 Aug, 139(2), 460 - 7
Spontaneous and induced rho mutants of Saccharomyces cerevisiae: patterns of loss of mitochondrial genetic markers; Heude M et al.; The deletion which leads to spontaneous rho mutants occurs preferentially at a unique region covering genes oxi3, pho1/OII, and mit175 . The frequency of loss of genetic markers in this region was significantly higher than in other regions as determined with a 15- marker system . When various mutagenic treatments were applied, this specific pattern of deletion was also observed, but it was dramatically amplified . This suggests that the basic mechanism of rho production is the same in yeast mitochondrial genomes in both spontaneous and induced mutants.

J Bacteriol, 1979 Aug, 139(2), 333 - 8
Saccharomyces cerevisiae mutant defective in exo-1,3-beta-glucanase production; Santos T et al.; Saccharomyces cerevisiae S288C produced two laminarinases (1,3-beta-glucanases) which were separated by diethylaminoethyl-Sephadex column chromatography; one was an endo-1,3-beta-glucanase, and the other was an exo-1,3-beta-glucanase active not only on laminarin but also on pustulan (1,6-beta-glucan) and on p-nitrophenyl-beta-D-glucoside . A mutant defective in the production of this last enzyme was isolated, and the mutation was named exb1-1 . The selection procedure was based on the capacity of exo-1,3-beta-glucanase to hydrolyze synthetic glucosides . The level of endo-1,3-beta-glucanase in cell extracts of the mutant was normal, but the exo-1,3-beta-glucanase could not be detected by column chromatographic analysis of these extracts . The mutant phenotype, recessive in heterozygous diploids, was stable through successive meioses and showed a Mendelian segregation, indicating that the mutation affected a single gene, which was named EXB1 . The lack of production of exo-1,3-beta-glucanase persisted through all the phases of growth, but growth itself was not impaired by the enzyme deficiency.

J Bacteriol, 1979 Aug, 139(2), 566 - 72
Localization of dolichyl phosphate- and pyrophosphate-dependent glycosyl transfer reactions in Saccharomyces cerevisiae; Marriott M et al.; Membranes from Saccharomyces cerevisiae protoplasts were fractionated on a continuous sucrose gradient . Six bands were obtained, which contained altogether about 15% of the total cell protein . From their densitites, their behavior in the presence and absence of Mg2+ ions, and the distribution of marker enzymes, it was possible to identify fractions enriched in rough and smooth endoplasmic reticulum and in mitochondria . All glycosyl transfer reactions investigated where dolichyl phosphates served as glycosyl acceptors or where dolichyl phosphate- and pyrophosphate-activated sugars served as glycosyl donors showed the highest specific activity and up to 75% of the total activity in the endoplasmic reticulum . This was the case for the reactions involved in the formation of O-glycosidic as well as N-glycosidic linkages in yeast glycoprotein biosynthesis . Membrane fractions enriched in plasmalemma contained less than 3% of the corresponding activities.

J Bacteriol, 1979 Aug, 139(2), 686 - 9
Regulation of Saccharomyces cerevisiae nicotinamide adenine dinucleotide phosphate-dependent glutamate dehydrogenase by proteolysis during carbon starvation; Mazon MJ et al.; Inactivation of the nicotinamide adenine dinucleotide phosphate-dependent glutamate dehydrogenase from Saccharomyces cerevisiae during carbon starvation occurs with a simultaneous loss of enzyme protein and enzyme activity.

Mol Gen Genet, 1979 Jul 13, 174(2), 163 - 71
Dual regulation of the synthesis of the arginine pathway carbamoylphosphate synthase of Saccharomyces cerevisiae by specific and general controls of amino acid biosynthesis; Pierard A et al.; The synthesis of the arginine pathway carbamoylphosphate synthase (CPSase A) of Saccharomyces cerevisiae is subject to two control mechanisms . One mechanism is specific for CPSase A and is exerted by arginine; it probably involves a repressor-operator type of interaction . This "specific" mechanism regulates the expression of gene cpaI coding for the small "glutaminase" subunit of CPSase A but has little influence on the production of the large subunit of the enzyme, a product of gene cpaII . This large component, which alone has no biological significance, accumulates freely under conditions of arginine repression . The second mechanism is general: it controls enzyme synthesis in a number of amino acid biosynthetic pathways in addition to the arginine sequence . Two types of evidence that this "general" mechanism participates in the control of CPSase A synthesis are presented: (1) Derepression upon starvation for any amino acid of which the synthesis is subject to this general control; and (2) repression during growth in amino acid-rich medium . In contrast to the specific mechanism, the "general" mechanism regulates the expression of both the cpaI and cpaII genes.

Biochim Biophys Acta, 1979 Jul 4, 585(3), 383 - 8
Stimulation of dehydrogenase synthesis by cadmium in a cadmium-resistant strain of Saccharomyces cerevisiae; Joho M et al.; The activity of dehydrogenase in Saccharomyces cerevisiae was estimated by reduction of 2,3,5-triphenyltetrazolium chloride . By the adaptation of yeast to cadmium, the high activity of dehydrogenase was observed . Furthermore, the activity of dehydrogenase in Cd-resistant cells was increased by growing in medium containing CdSO4 . However, the activity of dehydrogenase was inhibited by the addition of CdSO4 to the reaction mixture . The activity of dehydrogenase in Cd-sensitive cells was increased slightly by incubation with low concentrations of CdSO4 . High activity of dehydrogenase in Cd-resistant cells was completely negated by the addition of cycloheximide to the incubation medium . The increase of dehydrogenase activity is due partly to de novo synthesis of protein.

Genetics, 1979 Jul, 92(3), 777 - 82
Gene conversion of the mating-type locus in Saccharomyces cerevisiae; Klar AJ et al.; Tetrad analysis of MATa/MAT alpha diploids of Saccharomyces cerevisiae generally yields 2 MATa:2MAT alpha meiotic products . About 1 to 1.8% of the tetrads yield aberrant segregations for this marker . Described here are experiments that determine whether the aberrant meiotic segregations at the mating-type locus are ascribable to gene conversions or to MAT switches, that is, to mating-type interconversions . Diploid strains incapable of switching MATa to MAT alpha, or the converse, nevertheless display changes of MATa to MAT alpha, or the reverse . These events must be attributed to gene conversion . Further, we suggest that MATa and MAT alpha alleles may represent nonhomologous sequences of DNA since they fail to display postmeiotic segregations.

Genetics, 1979 Jul, 92(3), 759 - 76
Switching of a mating-type a mutant allele in budding yeast Saccharomyces cerevisiae; Klar AJ et al.; Aimed at investigating the recovery of a specific mutant allele of the mating type locus (MAT) by switching a defective MAT allele, these experiments provide information bearing on several models proposed for MAT interconversion in bakers yeast, Saccharomyces cerevisiae . Hybrids between heterothallic (ho) cells carrying a mutant MAT a allele, designated mata-2, and MAT alpha ho strains show a high capacity for mating with MATa strains . The MAT alpha/mata-2 diploids do not sporulate . However, zygotic clones obtained by mating MAT alpha homothallic (HO) cells with mata-2 ho cells are unable to mate and can sporulate . Tetrad analysis of such clones revealed two diploid (MAT alpha/MATa):two haploid segregants . Therefore, MAT switches occur in MAT alpha/mata-2 HO/ho cells to produce MAT alpha/Mata cells capable of sporulation . In heterothallic strains, the mata-2 allele can be switched to a functional MAT alpha and subsequently to a functional MATa . Among 32 MAT alpha to MATa switches tested, where the MAT alpha was previously derived from the mata-2 mutant, only one mata-2 like isolate was observed . However, the recovered allele, unlike the parental allele, complements the matalpha ste1-5 mutant, suggesting that these alleles are not identical and that the recovered allele presumably arose as a mutation of the Mat alpha locus . No mata-2 was recovered by HO-mediated switching of MAT alpha (previously obtained from mata-2 by HO) in 217 switches analyzed . We conclude that in homothallic and heterothallic strains, the mata-2 allele can be readily switched to a functional MAT alpha and subsequently to a functional MATa locus . Overall, the results are in accord with the cassette model (HICKS, STRATHERN and HERSKOWITZ )977b) proposed to explain MAT interconversions.

Genetics, 1979 Jul, 92(3), 749 - 58
Mating-type effect on cis mutations leading to constitutivity of ornithine transaminase in diploid cells of Saccharomyces cerevisiae; Deschamps J et al.; Cis-acting regulatory mutations have been isolated that affect L-ornithine transaminase (OTAse), an enzyme catalyzing the second step of arginine breakdown in yeast . These mutations lead to constitutive synthesis of OTAse at various levels . Two different types of mutations have been recovered, both of which are tightly linked to the structural gene (cargB) for this enzyme . One type behaves as a classical operator-constitutive mutation similar to the cargB+O---1 mutation previously described (DUBOIS et al . 1978) . The second type is peculiar in two respects: the higher level of constitutive OTAse synthesis and the expression of constitutivity in diploid cells . These mutations are designated cargB+Oh . They behave as usual operator-constitutive mutations in diploid strains homozygous for mating type (a/a or alpha/alpha), but the constitutivity is strongly reduced in a/alpha diploid cells.

Arch Microbiol, 1979 Jul, 122(1), 49 - 55
Inhibitory effect of ethanol on growth and solute accumulation by Saccharomyces cerevisiae as affected by plasma-membrane lipid composition; Thomas DS et al.; Incorporation of ethanol (1.0 or 1.25 M) into exponential-phase cultures of Saccharomyces cerevisiae NCYC 366 growing anaerobically in a medium supplemented with ergosterol and an unsaturated fatty acid caused a retardation in growth rat, which was greater when the medium contained oleic rather than linoleic acid . Ethanol incorporation led to an immediate drop in growth rate, and ethanol-containing cultures grew at the slower rate for at least 10 h . Incorporation of ethanol (0.5 M) into buffered (pH 4.5) cell suspensions containing D-{6-3H} glucose, D-{1-14C} glucosamine, L-{U-14C} lysine or arginine, or KH232PO4 lowered the rate of solute accumulation by cells . Rates of accumulation of glucose, lysine and arginine were retarded to a greater extent when cells had been grown in the presence of oleic rather than linoleic acid . This difference was not observed with accumulation of phosphate . Ethanol was extracted from exponential-phase cells by four different methods . Cells grown in the presence of linoleic acid contained a slightly, but consistently, lower concentration of ethanol than cells grown in oleic acid-containing medium . The ethanol concentration in cells was 5-7 times greater than that in the cell-free medium.

Mutat Res, 1979 Jul, 67(3), 215 - 9
Recombinogenicity and mutagenicity of saccharin in Saccharomyces cerevisiae; Moore CW et al.; Diploid yeast grown in the presence of a commercial lot of saccharin exhibited reproducible, dose-dependent increases in intergenic and intragenic recombination, and mutation . Cells grew to nearly the same titer in media without saccharin and containing 2 or 20 mg saccharin/ml, although cell viability was somewhat reduced in saccharin-containing media . At the high test dose of 100 mg/ml, titers and cell viability were more markedly lowered . Differences between this study and previous (negative) tests of saccharin in yeast are described.

Mutat Res, 1979 Jul, 61(2), 197 - 205
Mutagenesis of Saccharomyces cerevisiae by sodium azide activated in barley; Veleminsky J et al.; Concentrated dialysate of the extract prepared from barley seeds treated with sodium azide increased up to 100--200 times the frequency of forward mutations to cycloheximide resistance in the excision-deficient UV-sensitive heploid strain rad2-5 of Saccharomyces cerevisiae, when applied to growing cells in complete medium at pH 4.2 . Only a slight increase of mutation frequency (less than 4 times) was found in the haploid RAD+ strain treated in the same way as well as in haploid RAD+ and rad2-5 strains treated directly by sodium azide . In contrast with the barley-activated sodium azide, UV irradiation was more effective in the induction of cycloheximide resistance in the RAD+ strain than in the RAD2-5 mutant . The dialysate from azide-treated barley seeds, applied at both pH 4.2 and pH 9, also significantly increased the frequency of locus-specific suppressor mutations to isoleucine independence and -- to a lesser extent -- reversions and/or gene conversions in the trp5 locus in growing cells of the diploid strain D7 . The dialysate was also mutagenic in resting cells of strains D7 and rad2-5 but with lower effectiveness.

J Bacteriol, 1979 Jul, 139(1), 220 - 4
Peptidase activities in Saccharomyces cerevisiae; Rose B et al.; At least four distinct aminopeptidase activities and a single dipeptidase activity were found in cell extracts of a leucine-lysine auxotroph of Saccharomyces cerevisiae . The assay for peptidase activity involved polyacrylamide gel electrophoresis followed by an enzyme-coupled activity staining procedure . The aminopeptidases had largely overlapping specificities but could be distinguished from one another by their electrophoretic mobilities and activities toward different peptide substrates . Substrates tested included both free and blocked di- and tripeptides and amino acid derivatives.

J Biol Chem, 1979 Jun 25, 254(12), 5466 - 74
Isolation and characterization of a gene coding for glyceraldehyde-3-phosphate dehydrogenase from Saccharomyces cerevisiae; Holland MJ et al.; A yeast glyceraldehyde-3-phosphate dehydrogenase gene has been isolated from a collection of Escherichia coli transformants containing randomly sheared segments of yeast genomic DNA . Complementary DNA, synthesized from partially purified glyceraldehyde-3-phosphate dehydrogenase messenger RNA, was used as a hybridization probe for cloning this gene . The isolated hybrid plasmid DNA has been mapped with restriction endonucleases and the location of the glyceraldehyde-3-phosphate dehydrogenase gene within the cloned segment of yeast DNA has been established . There are approximately 4.5 kilobase pairs of DNA sequence flanking either side of the glyceraldehyde-3-phosphate dehydrogenase gene in the cloned segment of yeast DNA . The isolated hybrid plasmid DNA has been used to selectively hybridize glyceraldehyde-3-phosphate dehydrogenase messenger RNA from unfractionated yeast poly(adenylic acid)-containing messenger RNA . The nucleotide sequence of a portion of the isolated hybrid plasmid DNA has been determined . This nucleotide sequence encodes 29 amino acids which are at the COOH terminus of the known amino acid sequence of yeast glyceraldehyde-3-phosphate dehydrogenase.

J Biol Chem, 1979 Jun 10, 254(11), 4617 - 23
Assembly of the mitochondrial membrane system . The DNA sequence of a mitochondrial ATPase gene in Saccharomyces cerevisiae; Macino G et al.; The mitochondrial DNA of a cytoplasmic "petite" mutant (DS400/A3) of Saccharomyces cerevisiae has been characterized by restriction endonuclease analysis and by DNA sequencing . The DNA has a repeat length of 1,800 base pairs and contains the oli 1 and pho 2 loci, two known markers of the ATPase proteolipid subunit . The nucleotide sequence has helped to establish the presence in the DS400/A3 DNA of the proteolipid gene flanked by two long stretches of DNA rich in A + T . The sequence of the structural gene is in excellent agreement with the previously reported primary structure of the proteolipid . The DNA sequence also indicates that the mitochondrial codons of yeast are highly nondegenerate . The proteolipid gene has been precisely localized on the restriction map of the wild type genome . In addition, it has been possible to orient the gene with respect to other genetic markers and to determine the direction of its transcription.

Mol Gen Genet, 1979 Jun 7, 173(2), 203 - 10
Saccharomyces cerevisiae mutants defective in the maturation of ribosomal RNA; Venkov PV et al.; Slow-growing mutants were isolated after mutagenesis of the osmotic-sensitive strain Saccharomyces cerevisiae VY1160 . The isolated mutants in rich media have generation times from 300 to 400 min at 30 degrees C . Studies on the biosynthesis of rRNAX have shown, that the processing of 37S pre-rRNA in 6 of the slow-growing mutants occurs 3 to 4 times slower than in the parental strain . These mutants with decreased rate of rRNA maturation are of two different types . In some of them the processing of both 37S and 27S pre-rRNA is slowed down, while the mutants from the second group are acharacterized by a specific inhibition of the step 27S pre-rRNA leads to 25S rRNA . Experiments in which the synthesis of macromolecules was studied, have shown that in the mutants and in the parental strain, RNA and proteins are synthesized at comparable rates . Preliminary results suggest that the decreased rate of rRNA processing in three of the isolated mutants might be due to an insufficient function of the enzymes involved in the maturation of rRNA.

Mol Gen Genet, 1979 Jun 7, 173(2), 145 - 51
Isolation and characterisation of a strain of Saccharomyces cerevisiae deficient in in vitro RNA polymerase B(II) activity; Winsor B et al.; Two hundred strains of Saccharomyces cerevisiae temperature sensitive for RNA synthesis were selected and screened in crude extracts for DNA-dependent RNA polymerase activities . One strain was isolated which had only residual in vitro RNA polymerase B activity . In normal growth conditions total RNA, poly A+ RNA and protein synthesis were indistinguishable from those of the wild type strain at 23 degrees C and after shift to 37 degrees C . A temperature sensitive phenotype was detected only when rpoB containing strains were grown in adverse conditions . The mutant character showed mendelian segregation and was coexpressed with the wild type character in heterozygous diploids . Residual enzyme activity was characterised in crude extracts using synthetic polymers and natural templates in different ionic conditions.

Mol Gen Genet, 1979 Jun 7, 173(2), 211 - 2
Pieiotropic effect of two cell wall mutants on the activity of some cell wall enzymes in the yeast Saccharomyces cerevisiae; Lange P; The two mutants (abs) and (wal) affecting the cell morphology of yeast lead also to higher in vivo activities of the cell wall enzymes acid phosphatase, invertase and melibiase.

Genetics, 1979 Jun, 92(2), 383 - 96
A cluster of three genes responsible for allantoin degradation in Saccharomyces cerevisiae; Cooper TG et al.; Mutant strains of Saccharomyces cerevisiae unable to utilize allantoin as sole nitrogen source were isolated and divided into three groups on the basis of their biochemical and genetic characteristics . The three loci associated with these mutant classes were designated dal1 (allantoinase minus), dal2 (allantoicase minus) and dal4 (allantoin transport minus) . All three loci are located in a cluster that is proximal to the lys1 locus on the right arm of chromosome IX . The gene order and intergenic distances were estimated to be: dal1--2.5 cM--dal4--1.9cM--dal2--4.6cM-lys1.

Can J Biochem, 1979 Jun, 57(6), 932 - 7
A novel assay for endonucleases acting at apurinic sites and its use in measuring AP endonuclease activity in repair-deficient mutants of Saccharomyces cerevisiae; Futcher AB et al.; A quick and convenient assay for depurination and AP endonuclease activities has been developed . (The term 'AP endonuclease' refers to a nuclease that acts on apurinic and probably apyrimidinic sites on DNA.) It is based on the observation that different topological forms of DNA, such as open circular DNA and covalently closed circular DNA, bind different amounts of the fluorescent intercalator ethidium bromide, and can therefore be distinguished by their fluorescence . This assay has been used to measure AP endonuclease activity in 22 repair-deficient mutants of Saccharomyces cerevisiae . All 22 had normal or nearly normal AP endonuclease activity . The AP endonuclease activity was partially characterized.

Mutat Res, 1979 Jun, 61(1), 37 - 55
Radiation-induced mitotic and meiotic aneuploidy in the yeast Saccharomyces cerevisiae; Parry JM et al.; A number of genetic systems are described which in yeast may be used to monitor the induction of chromosome aneuploidy during both mitotic and meiotic cell division . Using these systems we have been able to demonstrate the induction of both monosomic and trisomic cells in mitotically dividing cells and disomic spores in meiotically dividing cells after both UV light and X-ray exposure . The frequency of UV-light-induced monosomic colonies were reduced by post-treatment with photoreactivity light and both UV-light- and X-ray-induced monosomic colonies were reduced by liquid holding post-treatment under non-nutrient conditions . Both responses indicate an involvement of DNA-repair mechanisms in the removal of lesions which may lead to monosomy in yeast . This was further confirmed by the response of an excision-defective yeast strain which showed considerably increased sensitivity to the induction of monosomic colonies by UV-light treatment at low doses . Yeast cultures irradiated at different stages of growth showed variation in their responses to both UV-light and X-rays, cells at the exponential phase of growth show maximum sensitivity to the induction of monosomic colonies at low doses whereas stationary phase cultures showed maximum induction of monosomic colonies at high does . The frequencies of X-ray-induced chromosome aneuploidy during meiosis leading to the production of disomic spores was shown to be dependent upon the stage of meiosis at which the yeast cells were exposed to radiation . Cells which had proceeded beyond the DNA synthetic stage of meiosis were shown to produce disomic spores at considerably lower radiation doses than those cells which had only recently been inoculated into sporulation medium . The results obtained suggest that the yeast sustem may be suitable for the study of sensitivities of the various stages of meiotic cell division to the induction of chromosome aneuploidy after radiation exposure.

Genetika, 1979 Jun, 15(6), 1024 - 32
{Genetic effects of sulfur-35 decay in Saccharomyces cerevisiae cells . V . Comparative study of the lethal and mutagenic effectiveness of the decay of 35S and 32P incorporated into cells of the radiosensitive mutant xrs2}; Korolev VG et al.; The lethal effect of 35S and 32P decays on cells of yeast radiation-sensitive mutant xrs2 was studied . The mutant is 7 times more sensitive than the wild type to transmutation of both isotopes . The survival curve for xrs2 was exponential . In spite of the lethal effect, mutant cells are not more mutable than the wild type under decays of both isotopes (the number of mutations in ade1 and ade2 genes was counted), xrs2 and wild type strains differ in kinds of mutations induced by the decay of incorporated 35S in ade2 locus . Namely, there are 82% of base substitutions and 18% of other types mutations induced in xrs2 strain despite 97% and 3% respectively for the wild type strain . Also it was shown that complete and mosaic mutants, induced by the the 35S decay in xrs2 strain, differ in a pattern of interallelic complementation.

J Bacteriol, 1979 Jun, 138(3), 816 - 22
Isolation and preliminary characterization of Saccharomyces cerevisiae proline auxotrophs; Brandriss MC; Proline-requiring mutants of Saccharomyces cerevisiae were isolated . Each mutation is recessive and is inherited as expected for a single nuclear gene . Three complementation groups cold be defined which are believed to correspond to mutations in the three genes (pro1, pro2, and pro3) coding for the three enzymes of the pathway . Mutants defective in the pro1 and pro2 genes can be satisfied by arginine or ornithine as well as proline . This suggests that the blocks are in steps leading to glutamate semialdehyde, either in glutamyl kinase or glutamyl phosphate reductase . A pro3 mutant has been shown by enzyme assay to be deficient in delta 1-pyrroline-5-carboxylate reductase which converts pyrroline-5-carboxylate to proline . A unique feature of yeast proline auxotrophs is their failure to grown on the rich medium, yeast extract-peptone-glucose . This failure is not understood at present, although it accounts for the absence of proline auxotrophs in previous screening for amino acid auxotrophy.

Arch Microbiol, 1979 Jun, 121(3), 225 - 9
Rapid decrease of ATP content in intact cells of Saccharomyces cerevisiae after incubation with low concentrations of sulfite; Schimz KL et al.; Sulfite, at concentrations above 1 mM and at a pH below 4, caused cell death in Saccharomyces cerevisiae X2180 as measured by the colony-forming capacity . A rapid decrease in the ATP content was observed prior to cellular death . The depletion of ATP was reversible and the lethal effect could be prevented if the cells were exposed to sulfite for periods of less than 1 h . Extent and rate of ATP depletion were dependent on time, pH value, temperature and sulfite concentrations.

J Biol Chem, 1979 May 10, 254(9), 3326 - 32
Characterization of the plasma membrane Mg2+-ATPase from the yeast, Saccharomyces cerevisiae; Willsky GR; The plasma membrane of Saccharomyces cerevisiae has a Mg2+-dependent ATPase which is distinct from the mitochondrial Mg2+-ATPase and at the pH optimum of 5.5 has a Km for ATP of 1.7 mM and a Vmax of 0.42 mumol of ATP hydrolyzed/mg/min . At least three protein components of the crude membrane (Mr = 210,000, 160,000 and 115,000) are labeled with {gamma"32P}ATP at pH 5.5 . These phosphoproteins form rapidly in the presence of Mg2+, rapidly turn over the bound phosphate when unlabeled ATP is added, and dephosphorylate after incubation in the presence of hydroxylamine . Vanadate, an inhibitor of the Mg2+-ATPase activity, blocks the phosphorylation of the 210,000- and 115,000-dalton proteins . At pH 7.0, only the 210,000- and 160,000-dalton proteins are phosphorylated . While these three phosphorylated intermediates have not been unambiguously identified as components of the Mg2+-ATPase, the finding of such phosphorylated components in association with that activity implies that this enzyme differs in mechanism from the mitochondrial proton pump and that it is similar in mechanism to the metal ion pumps ((Na+-K+)-ATPase and Ca2+-ATPase) of the mammalian plasma membrane.

Ann Microbiol (Paris), 1979 May-Jun, 130 A(4), 419 - 33
{Release of "Saccharomyces cerevisiae" protoplasts: scanning electron microscope study (author's transl)}; Bastide M et al.; In a previous study we described the minimal methodology used to obtain protoplasts from ascomycetous yeasts . Using a reducing agent associated with 1,3-beta-glucanase at 26 degrees C, protoplasts were invariably obtained . In the present study we localized the disruption spots of the cell wall using the two same reagents . The observations were made with the scanning electron microscope . The disruption site was always in the subterminal region, and this very simple structure (proteins with disulphide bridges and 1,3-beta-glucans) was opposite the birth-scar . The dissociation of the two reagents showed that a small part of the yeast population was able to release protoplasts with only glucanase . We believe these very sensitive yeasts (2 to 10% population) to be very young cells . These disruption sites seemed very different from budding-sites . They might be identical with elongation-sites, or with the opening in the ascus-wall during germinating ascospore release.

Biochem J, 1979 May 1, 179(2), 315 - 25
Thiamin biosynthesis in Saccharomyces cerevisiae . Origin of carbon-2 of the thiazole moiety; White RL et al.; Radioactivity from {2-14C}glycine enters C-2 of the thiazole moiety of thiamin and no other site, in Saccharomyces cerevisiae (strains A.T.C.C . 24903 and 39916, H.J . Bunker) . Radioactivity from L-{Me-14C}methionine or from DL-{2-14C}tyrosine does not enter thiamin.

J Bacteriol, 1979 May, 138(2), 638 - 41
Suppressor of deoxythmidine monophosphate uptake in Saccharomyces cerevisiae; Remer S et al.; Although yeast cannot normally incorporate exogenous deoxythymidine 5'-monophosphate (dTMP) into deoxyribonucleic acid, mutants able to do so have been isolated . We have characterized a recessive suppressor of dTMP uptake (sot1) that prevents strains carrying either tup1, tup2, or tup4 from growing on selective medium . The sot1 mutation maps between rad1 and the centromere of chromosome XVI, and is unlinked to any of the tup mutations . The sot1 mutation does not suppress the other pleiotropic effects of the tup1 mutant, notably the lack of mating of tup1 MATalpha strains . The sot1 mutation specifically blocks the uptake of dTMP into tup strains . After growing a sot1 strain in medium containing {3H}dTMP, we showed that the medium still contained more than 90% of the original {3H}dTMP and that this medium could support the incorporation of {3H}dTMP by a tup2 strain . Therefore, sot1 strains do not degrade dTMP in the medium . The sot1 mutation had no effect on the uptake of other nutrients essential for growth, including several amino acids, adenine, and uracil.

J Bacteriol, 1979 May, 138(2), 542 - 51
Structure of polyadenylic acid in the ribonucleic acid of Saccharomyces cerevisiae; Phillips SL et al.; Investigations of the structure of polyadenylic acid {poly(A)} in yeast have shown that there are two classes of poly(A) distinguished by size and kinetics of synthesis . Each class is found directly on the 3' end of messenger RNA . One class contains poly(A) molecules ranging from 60 to less than 20 nucleotides long . The longest molecules in this poly(A) class are the first to become labeled when cells are exposed to {3H}adenine . Label then appears in progressively smaller molecules . The second class of poly(A) is about 20 nucleotides long . The length homogeneity of this class and the presence in nuclear DNA of many copies of a polythymidylate sequence which is the same length suggests that this poly(A) is synthesized by transcription from DNA.

Histochem J, 1979 May, 11(3), 299 - 310
A cytochemical study of the localization of acid phosphatase in Saccharomyces cerevisiae at different growth phases; Rainina EI et al.; The localization of acid phosphatase in the yeast Saccharomyces cerevisiae at different growth phases had been studied . It was shown to be crucial for authentic location of acid phosphatase that the cytochemical reaction be performed on whole cells . Dimethylsulphoxide was used to alleviate the effects of fixation of the yeast cells with glutaraldehyde; the sulphoxide did not affect the distribution of acid phosphatase in the cells . It has been established that in exponentially-growing cells acid phosphatase is localized mostly in small vacuolar compartments . In mature cells, the bulk of acid phosphatase is found in the central vacuole, although a significant amount of the enzyme is detectable in the plasma membrane and the adjacent vesicles.

Mutat Res, 1979 Apr, 60(2), 163 - 71
The mutagenic potential of unexcised pyrimidine dimers in Saccharomyces cerevisiae, rad1-1: evidence from photoreactivation and pedigree analysis; Kilbey BJ et al.; Photoreactivation and pedigree analysis have been combined to show that unexcised pyrimidine dimers in the DNA of rad1-1 yeast can initiate mutagenesis after passing through several DNA replications . Monomerisation of dimers immediately before the second replication to follow UV has no effect on mutants appearing after the first post-UV cell division but reduces second-generation mutants to one third of their frequency in the dark and has a similar through slightly less marked effect on mutants appearing in the third or subsequent generations . The bearing of these findings on the mechanism of UV mutagenesis is dicussed.

Proc Natl Acad Sci U S A, 1979 Apr, 76(4), 1858 - 62
Secretion and cell-surface growth are blocked in a temperature-sensitive mutant of Saccharomyces cerevisiae; Novick P et al.; Saccharomyces cerevisiae cells contain a small internal pool of the secretory enzymes invertase and acid phosphatase . This pool increases up to 8-fold at 37 degrees C in a temperature-sensitive, secretion-defective mutant strain (sec 1-1) . Cell division and incorporation of a sulfate permease activity stop abruptly at the restrictive temperature, while protein synthesis continues for several hours . Electron microscopy of mutant cells incubated at 37 degrees C reveals a large increase in the number of intracellular membrane-bound vesicles, which are shown by histochemical staining to contain the accumulated acid phosphatase . The vesicles are removed and the accumulated enzymes are secreted when cells are returned to a permissive temperature in the presence or absence of cycloheximide . These results are consistent with a vesicle intermediate in the yeast secretory pathway and suggest that exocytosis may contribute to cell-surface growth.

Eur J Biochem, 1979 Apr, 95(3), 469 - 75
Purification and partial characterization of a factor, a mating hormone produced by mating-type-a cells from Saccharomyces cerevisiae; Betz R et al.; Cells of Saccharomyces cerevisiae exhibiting the a mating type secrete into the culture medium a mating-type-specific hormone activity (a factor), which specifically causes a transient arrest of DNA replication and cell division in cells of the opposite mating type, alpha . Three compounds exhibiting a factor activity have been found in culture filtrates from a cells . The most active compound has been purified more than 10(5)-fold and appears to be homogeneous on the basis of thin-layer chromatography and thin-layer electrophoresis in different systems . We propose that this compound, which exhibits in alpha cells the biological activities that have been attributed to a factor, represents pure a factor . a factor has been characterized as a very hydrophobic undecapeptide with the following amino acid composition: H2N-Tyr (Asx1, Gly1, Ala1, Val1, Ile2, Phe1, Lys1, Trp1, Pro1) . Although in their respective target cells the biological effects of a factor and of alpha factor, the corresponding mating hormone of mating-type-alpha cells, are remarkably similar, the primary structures of both hormones appear to be quite different.

J Bacteriol, 1979 Apr, 138(1), 92 - 8
Dependency of size of Saccharomyces cerevisiae cells on growth rate; Tyson CB et al.; The mean size and percentage of budded cells of a wild-type haploid strain of Saccharomyces cerevisiae grown in batch culture over a wide range of doubling times (tau) have been measured using microscopic measurements and a particle size analyzer . Mean size increased over a 2.5-fold range with increasing growth rate (from tau = 450 min to tau = 75 min) . Mean size is principally a function of growth rate and not of a particular carbon source . The duration of the budded phase increased at slow growth rates according to the empirical equation, budded phase = 0.5 tau + 27 (all in minutes) . Using a recent model of the cell cycle in which division is thought to be asymmetric, equations have been derived for mean cell age and mean cell volume . The data are consistent with the notion that initiation of the cell cycle occurs at "start" after attainment of a critical cell size, and this size is dependent on growth rate, being, at slow growth rates, 63% of the volume of fast growth rates . Previous reports are reanalyzed in the light of the unequal division model and associated population equations.

J Bacteriol, 1979 Apr, 138(1), 60 - 9
Two-dimensional protein patterns during growth and sporulation in Saccharomyces cerevisiae; Trew BJ et al.; Proteins synthesized by Saccharomyces cerevisiae in presporulation and sporulation media were compared by using sporulating (a/alpha) and nonsporulating (a/a and alpha/alpha) yeast strains . Total cellular proteins were labeled with {35S}methionine and analyzed by two-dimensional polyacrylamide gel electrophoresis . Autoradiograms and/or fluorograms showed some 700 spots per gel . Nine proteins were synthesized by a/alpha cells which were specific to vegetative, log-phase conditions . During incubation in sporulation medium, sporulating (a/alpha) cells synthesized 11 proteins not present in vegetatively growing cell . These same 11 proteins, however, were synthesized by nonsporulating (a/a and alpha/alpha) cells on sporulation medium as well . Nonsporulating diploids (a/a and alpha/alpha) were also examined with the electron microscope at various times during their incubation in sporulation medium . Certain cellular responses found to be unique to meiotic yeast cells in previous studies were exhibited by the nonsporulating controls . The degree to which all cell types (a/alpha, a/a, and alpha/alpha) were committed to sporulation was also determined by shifting cells from sporulation medium to vegetative medium . Some commitment to the meiotic pathway was observed in both the a/alpha and the a/a, alpha/alpha cells.

J Bacteriol, 1979 Apr, 138(1), 162 - 70
Regulation of protein synthesis during early limitation of Saccharomyces cerevisiae; Swedes JS et al.; Arsenate, a competitive inhibitor with phosphate in phosphorylation reactions, has been used to lower adenine and guanine nucleotide levels in Saccharomyces cerevisiae to study nucleotide effects on protein synthesis . By measuring polysome levels, we have shown that initiation of protein synthesis is much more sensitive than elongation or termination to inhibition when the ATP/ADP, GTP/GDP ratios are low . When the arsenate-phosphate molar ratio was 0.27, protein synthesis was inhibited by about 85% and the kinetics of polysome decay was similar to that observed with the initiation inhibitor, verrucarin-76, or with the protein synthesis initiation mutant, ts187, at the restrictive temperature . With this level of arsenate, the adenylate energy charge dropped from 0.9 to 0.7 and the ATP/ADP and GTP/GDP ratios dropped from 6 to 2 . The observed correlations between nucleotide ratio changes and inhibition of protein synthesis suggest that the former may be a control signal for the latter . The significance of these in vivo correlations will have to be tested with an in vitro protein synthesizing system . Higher arsenate levels resulted in even lower ATP/ADP, GTP/GDP ratios and in a slower decay of polysomes, implying that, eventually, elongation (in addition to initiation) was being inhibited.

Biotechnol Bioeng, 1979 Apr, 21(4), 659 - 70
Process characteristics of cell lysis mutants of Saccharomyces cerevisiae; Boudrant J et al.; Several temperature-sensitive lysis mutants of Saccharomyces cerevisiae were selected according to their ability to release alkaline phosphatase when incubated at a nonpermissive temperature . For two mutants, cell lysis and release of alkaline phosphatase reached a maximum when cells in the logarithmic growth phase were shifted to the nonpermissive temperature . Morphological changes, as well as changes in macromolecular composition of the cells, were observed . Growth is necessary and oxygen is important for the expression of cell lysis at the nonpermissive temperature.

Biotechnol Bioeng, 1979 Apr, 21(4), 609 - 26
Investigation of the significance of a carbon and redox balance to the measurement of gaseous metabolism of Saccharomyces cerevisiae; Barford JP et al.; A complete carbon and redox balance for Saccharomyces cerevisiae grown in batch culture with ethanol as the limiting carbon and energy source is reported . A novel method, which allowed the determination of carbon dioxide contained in the culture medium and biomass, is described and revealed amounts considerably in excess of what was expected from equilibrium data . Furthermore, elemental composition of the biomass was used to calculate the amount of oxygen required for biosynthetic reactions . When these corrections are applied to experimentally measured gas metabolism data, apparently anomalous results are shown to be consistent with the overall metabolism of bakers' yeast . These findings have wide implications to the quantitative study of the metabolism and energetics of facultative aerobes.

Mol Gen Genet, 1979 Mar 27, 171(3), 335 - 41
Comparison of amino acid compositions of mitochondrial and cytoplasmic ribosomal proteins of Saccharomyces cerevisiae; Faye G et al.; The amino-acid compositions of the mitochondrial ribosomal subunits of Saccharomyces cerevisiae have been determined and compared to those of cytoplasmic ribosomal subunits . For the large subunits, the mitochondrial and cytoplasmic ribosomes showed major differences in the proportions of arginine, alanine and methionine . For the small subunits, arginine, aspartic acid, alanine, valine and methionine showed marked differences . We have compared these amino-acid compositions with those already published of bacterial and eukaryotic ribosomes by a statistical method of data analysis . It appeared clearly that the yeast mitoribosomes are more distant from bacterial ribosomes than from eukaryotic cytoribosomes.

Biochim Biophys Acta, 1979 Mar 27, 577(1), 217 - 20
Isolation of a thiamine-binding protein from Saccharomyces cerevisiae; Iwashima A et al.; Thiamine-binding protein was isolated from Saccharomyces cerevisiae by successive procedures of cold osmotic shock treatment, DEAE-cellulose chromatography and ultrafiltration . The purified thiamine-binding protein was an electrophoretically homogeneous molecule which appeared to be a glycoprotein with a molecular weight of 140 000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis . No thiamine-binding protein was observed by disc gel electrophoresis in the shock fluid released from yeast cells grown in the presence of 1 muM thiamine, indicating that the formation of this protein is regulated by exogenous thiamine as previously suggested.

Biochem J, 1979 Mar 15, 178(3), 521 - 7
Interaction of cations with phosphate uptake by Saccharomyces cerevisiae . Effects of surface potential; Roomans GM et al.; The effect of bivalent cations on phosphate uptake by Saccharomyces cerevisiae was investigated . Phosphate uptake via the Na+-dependent transport system at pH 7.2 is stimulated by bivalent cations . The apparent affinity of phosphate for the transport mechanism is increased, but the apparent affinity for Na+ is decreased . Uptake of phosphate via the Na+-independent transport system is accompanied by a net proton influx of 2H+ and an efflux of 1 K+ for each phosphate ion taken up . At pH 4.5 phosphate uptake via the Na+-independent system is stimulated by bivalent cations, whereas at pH 7.2 uptake is inhibited . The effect of bivalent cations on phosphate uptake can be ascribed to a decrease in the surface potential.

Mol Gen Genet, 1979 Mar 5, 170(3), 351 - 4
Genetic analysis of an osmotic sensitive Saccharomyces cerevisiae mutant; Kozhina T et al.; The genetic analysis of VY1160 sorbitol dependent, osmotic sensitive yeast mutant led to the identification of three different nuclear recessive mutations . Two of them, designated sorb- and ts1 are closely linked to one another . The mutation sorb- determines the lysis, while the mutation ts1 increases the ability for lysis of the sorbitol dependent cells . The third mutation ts2 segregates independently from the other two and confers the sensitivity of VY1160 mutant cells towards rifampicin.

Cell Biol Int Rep, 1979 Mar, 3(2), 129 - 34
Size of poly (A) +-mRNA in Saccharomyces cerevisiae polysomes; Mateeva ZE et al.; The size of poly (A) +-mRNA in different classes of yeast polysomes is estimated . The average molecular weight of long-term labelled polysomal poly (A) +-mRNA is about 0,65 x 10(6) daltons . Approximately 60% of the poly (A) +-mRNA polynucleotide chains located at the 5' end, are unprotected by ribosomes and degraded by nucleases upon incubation of cell lysates, to yield a population of poly (A) +-mRNA with an average molecular weight of 0,25 x 10(6) daltons.

J Bacteriol, 1979 Mar, 137(3), 1447 - 8
Addition of basic amino acids prevents G-1 arrest of nitrogen-starved cultures of Saccharomyces cerevisiae; Cooper TG et al.; Arginase-minus mutants of Saccharomyces cerevisiae were arrested in growth and accumulated at the unbudded G-1 stage of the cell cycle when starved for nitrogen . If, however, arginine was added to the culture medium at the time of starvation, growth ceased but the cells did not collect at the unbudded G-1 stage . We suggest that arginine addition prevented the cells from collecting at the G-1 stage by starving them for histidine and lysine, thereby inhibiting synthesis of proteins needed to complete the cell cycle.

Int J Pept Protein Res, 1979 Mar, 13(3), 253 - 9
Protease B from Saccharomyces cerevisiae . Purification and characterization; Looze Y et al.; Protease B has been isolated from Saccharomyces cerevisiae and purified in six steps as follows: autolysis of the yeast cells, ammonium sulfate fractionation, activation of the proteolytic enzymes, chromatography on DEAE-cellulose, chromatography on CM-cellulose and finally, a second chromatography on DEAE-cellulose . The preparation was shown to be homogeneous on polyacrylamide gels in the absence as well as in the presence of sodium dodecylsulfate . Furthermore, the molecular weight (43,000 daltons) and the isoelectric point (5.45) were in good agreement with earlier published values . The amino acid composition is reported . The absence of disulfide bonds in protease B has to be outlined . The amino acid residues of the protein have been found to be folded nearly quantitatively (at least 80%) in a beta-conformation as deduced from a circular dichroism study . Finally, the tryptophan residues (5 mol/mol protein) are largely buried in the hydrophobic core of the enzyme.

Can J Microbiol, 1979 Mar, 25(3), 380 - 9
Isolation and characterisation of guanine auxotrophs in Saccharomyces cerevisiae; Gardner WJ et al.; Mutants of yeast which are auxotrophic for guanine have been isolated from two prototrophic haploid strains, one of which carried the suppressor of purine excretion, su-pur, and the other carried the alternative allele, su-pur+ . The mutants were allocated to three genes, gual, gua2, and gua3, between which no close linkage was demonstrable . Mutants of all three genes were recessive and showed normal Mendelian segregation in crosses . The gene gual was shown by an in vivo enzyme assay procedure to specify guanosine 5'-phosphate (GMP) synthetase, the second enzyme involved in the biosynthesis of GMP from inosine 5'-phosphate (IMP) . Mutants of this gene excrete large amounts of purine derivatives, predominantly xanthosine, into guanine-free, but not into guanine-supplemented, medium . The gene gau2 is probably involved in the biosynthesis of riboflavin from guanine nucleotides; the phenotype of these mutants suggests a possible interaction between aromatic amino acid metabolism and riboflavin biosynthesis . No role for gua3 can be assigned on the evidence so far available, but it is not involved in the specification of IMP dehydrogenase, the first enzyme involved in the synthesis of GMP and IMP.

Eur J Biochem, 1979 Mar, 94(2), 409 - 17
Synthesis and activation of asparagine in asparagine auxotrophs of Saccharomyces cerevisiae; Ramos F et al.; L-Asparagine synthesis in Saccharomyces cerevisiae is performed by a glutamine-dependent asparagine synthetase of the type found in higher organisms . Auxotrophy for asparagine has been obtained in two classes of mutants . In class I, asparagine synthetase activity is cancelled . These mutants combine two mutations, asnA- and asnB- . Neither asnA- nor asnB- mutation alone leads to total auxotrophy . Partial auxotrophy as well as a strong decrease in enzyme activity result from asnA- mutation . No change is detectable in cells with the asnB- mutationalone . This, and Jones' report {J . Bacteriol . 134, 200-207 (1978)} of auxotrophy resulting from the combination of two mutations, are strong supports for asparagine synthesis being an unusual biosynthetic operation . In class II, auxotrophy results from a single mutation which leads to a modification of the efficiency of the asparaginyl-tRNA synthetase (asnRS- mutation) . This auxotrophy is cancelled if asparaginase I activity (the only one present in sigma 1278b wild type) is cancelled by casnI- mutation . This latter mutation allows an increase in the asparagine pool which is able to compensate for the asparaginyl-tRNA synthetase partial defect of the asnRS- mutant.

Mol Gen Genet, 1979 Feb 26, 170(2), 137 - 44
The half-life of mRNA in Saccharomyces cerevisiae; Chia LL et al.; The decay kinetics of mRNA was studied in a yeast temperature-sensitive mutant, ts136, which is defective in cytoplasmic RNA production at 37 degree C . The disappearance of the synthetic capacity of mRNA was determined by withdrawing equal volumes of ts136 cell culture and pulse-labelling with {35S}methionine at various time intervals after the shift to 37 degrees C from 23 degrees C . The synthesized proteins were separated on a two-dimensional gel electrophoretic system and then quantitatively analyzed for theri incorporated radioactivities by scintillation counting . Our results show that yeast mRNAs have divergent functional half-lives ranging from 4.5 to 41 min, with an average value of 22 min . Each mRNA exhibits a simple exponential decay with its own characteristic dacay pattern . Of the approximately 500 major polypeptides made by yeast cells, which are detectable on autoradiograms of the gels, 80 were arbitrarily selected and the mRNAs coding for those polypeptides were examined for their decay kinetics.

Mol Gen Genet, 1979 Feb 26, 170(2), 129 - 35
Individual messenger RNA half lives in Saccharomyces cerevisiae; Koch H et al.; We have measured the decay half-life of functional messenger RNA (mRNA) for some thirty different proteins in the yeast Saccharomyces cerevisiae . Production of newly synthesized mRNA was halted by raising the temperature of a culture of a temperature-sensitive mutant, ts 136 . Aliquots of this culture were pulsed-labelled with {35S}-methionine at various times after the temperature shift and the radioactive proteins separated on the two-dimensional gel electrophoresis system of O'Farrell . We find a range in the decay half lives of individual mRNA species which varies from 3.5 min to greater than 70 min . We find three general classes of decay curves, (a) simple exponential (first order); some of these showed a shoulder before onset of exponential decay; (b) bi-component or multi-component concave upward; (c) initial stimulation of rate of mRNA synthesis, followed by virtually undetectable decay.

Mol Gen Genet, 1979 Feb 16, 170(1), 89 - 92
The DNA repair capability of cdc9, the Saccharomyces cerevisiae mutant defective in DNA ligase; Johnston LH; The cell cycle mutant, cdc9, in the yeast Saccharomyces cerevisiae is defective in DNA ligase be deficient in the repair of DNA damaged by methyl methane sulphonate . On the other hand survival of cdc9 after irradiation by gamma-rays is little different from that of the wild-type, even after a period of stress at the restrictive temperature . The mutant cdc9 is not allelic with any known rad or mms mutants.

J Biol Chem, 1979 Feb 10, 254(3), 796 - 803
Metabolism of alpha-factor by a mating type cells of Saccharomyces cerevisiae; Finkelstein DB et al.; When a mating type cells of Saccharomyces cerevisiae are exposed to the mating pheromone alpha-factor in liquid cultures, there is a time-dependent loss of alpha-factor activity from the culture fluid . This loss of biological activity can be directly correlated with the proteolysis of the pheromone by a mating type cells . The metabolism of alpha-factor by a mating type cells may be measured by using either in vitro 125I-labeled or in vivo 35S-labeled pheromone . Addition of chloroquine to growing cultures of a mating type cells at concentrations which cause no detectable alterations in cell growth produces a potentiation of alpha-factor mediated cell cycle arrest . This potentiation of alpha-factor activity is directly correlated with the inhibition of alpha-factor proteolysis . Thus, while proteolytic digestion of alpha-factor appears to be related to the mechanism whereby a mating type cells "detoxify" alpha-factor and recover from cell cycle arrest, proteolysis of the mating factor is not necessary for alpha-factor mediated cell cycle arrest.

Cell, 1979 Feb, 16(2), 443 - 52
Isolation of galactose-inducible DNA sequences from Saccharomyces cerevisiae by differential plaque filter hybridization; St John TP et al.; Multiple nitrocellulose DNA filter replicas of plaques of in vitro generated recombinants of phage lambda and Saccharomyces cerevisiae have been screened by hybridization with 32P-labeled cDNA probes . These probes were representative of total poly(A)-containing RNA of yeast cells grown on acetate, galactose, glucose or maltose . This approach allows the use of specific differences in total RNA populations as probes for gene isolation . Five "galactose-induced" clones have been isolated . Expression of the RNA coding regions on at least two cloned sequences, Sc481 and Sc482, is regulated by genes known to control the expression of the structural genes required for the conversion of exogenous galactose to endogenous glucose-1-phosphate . One cloned sequence, Sc484, is expressed during growth on all carbon sources except glucose, and is not under control by the galactose regulatory genes . This clone contains a sequence that is repeated 3 times in the yeast genome . The cloned fragment Sc481 contains coding regions for all or part of three galactose"induced RNAs and may correspond to the GAL 1, GAL 7, GAL 10 gene cluster region of chromosome II.

J Bacteriol, 1979 Feb, 137(2), 1048 - 50
Synthesis of ribosomal proteins during the cell cycle of the yeast Saccharomyces cerevisiae; Elliott SG et al.; Centrifugal elutriation was used to separate yeast cells by their cell cycle position . The rate of synthesis of ribosomal proteins showed a constant exponential increase through the cell cycle.

Eur J Biochem, 1979 Feb 1, 93(3), 587 - 99
The dicyclohexylcarbodiimide-binding protein of the mitochondrial ATPase complex from Neurospora crassa and Saccharomyces cerevisiae . Identification and isolation; Sebald W et al.; Incubation of mitochondria from Neurospora crassa and Saccharomyces cerevisiae with the radioactive ATPase inhibitor {14C}dicyclohexylcarbodiimide results in the irreversible and rather specific labelling of a low-molecular-weight polypeptide . This dicyclohexylcarbodiimide-binding protein is identical with the smallest subunit (Mr 8000) of the mitochondrial ATPase complex, and it occurs as oligomer, probably as hexamer, in the enzyme protein . The dicyclohexylcarbodiimide-binding protein is extracted from whole mitochondria with neutral chloroform/methanol both in the free and in the inhibitor-modified form . In Neurospora and yeast, this extraction is highly selective and the protein is obtained in homogeneous form when the mitochondria have been prewashed with certain organic solvents . The bound dicyclohexylcarbodiimide label is enriched in the purified protein up to 50-fold compared to whole mitochondria . Based on the amino acid analysis, the dicyclohexylcarbodiimide-binding protein from Neurospora and yeast consists of at least 81 and 76 residues, respectively . The content of hydrophobic residues is extremely high . Histidine and tryptophan are absent . The N-terminal amino acid is tyrosine in Neurospora and formylmethionine in yeast.

Eur J Biochem, 1979 Feb 1, 93(3), 487 - 93
Yeast killer toxin: purification and characterisation of the protein toxin from Saccharomyces cerevisiae; Palfree RG et al.; Killer toxin from killer strains of Saccharomyces cerevisiae was isolated from concentrates of extracellular medium by precipitation in poly(ethylene glycol) and chromatography through glyceryl-controlled-pore glass . The toxin migrated as a single protein band on sodium dodecyl sulfate/polyacrylamide gel electrophoresis . A molecular weight of 11470 was determined for the toxin protein from its electrophoretic mobility and amino acid composition . Gel filtration of the active toxin indicated that the 11,470-Mr monomer was the active unit . Electrophoretic comparison of extracellular concentrates from a killer strain and an isogenic non-killer showed the presence of the toxin protein only in the killer-derived material . The activity of the toxin was most stable between pH 4.2 and 4.6 . At 30 degrees C toxin from a superkiller strain was more stable than that from a normal killer.

Mol Gen Genet, 1979 Jan 31, 169(2), 189 - 94
Production of petites by cell cycle mutants of Saccharomyces cerevisiae defective in DNA synthesis; Newlon CS et al.; Mutations in two genes (cdc8 and cdc21) required for nuclear and mitochondrial DNA synthesis in Saccharomyces cerevisiae result in a 6- to 11-fold increase in the rate of mitotic segregation of petites at the permissive temperature . The defect in DNA replication and the increased rate of petite production result from the same mutation since the two phenotypes cosegregate and corevert . Most of the petites isolated from strains carrying mutations in cdc8 and cdc21 contain mtDNA . Therefore, the petites do not result simply from an underreplication of mitochondrial DNA . The mutation rates for nuclear and mitochondrial genes are the same in cdc8, cdc21 and their wild-type parent . Therefore the petites are unlikely to result from an increase in the rate of base pair substitution.

Mol Gen Genet, 1979 Jan 31, 169(2), 183 - 8
Assembly of the mitochondrial membrane system: two separate genes coding for threonyl-tRNA in the mitochondrial DNA of Saccharomyces cerevisiae; Macino G et al.; 1 . Mitochondria of Saccharomyces cerevisiae contain two tRNA's that are acylated with threonine . The two isoaccepting species (tRNA1Thr and tRNA2Thr) can be separated by reversed-phase chromatography on RPC-5 . 2 . A cytoplasmic mutant has been isolated which lacks tRNA1Thr but has normal levels of tRNA2Thr . This mutation was previously shown to map between the oxi 1 and oxi 2 loci on mitochondrial DNA . 3 . tRNA1Thr and tRNA2Thr hybridize to wild type mitochondrial but not nuclear DNA and are capable of partially competing with each other . Hybridization of each species to different segments of mitochondrial DNA isolated from p- clones indicate that there are two threonyl tRNA genes . One gene is located between oxi 1 and oxi 2 and codes for tRNA1Thr . The second gene codes for tRNA2Thr and is near the cap locus . 4 . Binding assays to E . coli ribosomes indicate that tRNA2Thr recognizes the threonine triplet ACA and may also recognize the other three triplets but with a much lower efficiency . None of the four codons for threonine stimulate the binding of tRNA1Thr to the ribosomes.

Chromosoma, 1979 Jan 31, 70(3), 337 - 52
A probe into nuclear events during the cell cycle of Saccharomyces cerevisiae: studies of folded chromosomes in cdc mutants which arrest in G1; Pinon R; The sedimentation behavior of folded chromosomes from cell-division-cycle (cdc) mutants which arrest in G1 was examined . At the restrictive temperature the folded genome of cdc 7, which arrests after spindle pole body (SPB) separation and spindle formation, cosediments with a standard g1 structure, indicating that by the cdc 7 step the g1 form of the folded genome has been assembled . In the mutant, cdc 4, which arrests before SPB separation but after SPB duplication, a standard g1 structure is not formed . cdc 4 cells, however, are able to enter G0 at the restrictive temperature, and the corresponding go structure is stable . These results indicate that the cdc 4 gene product may be involved in the development of folded genome conformation which leads to the g1 structure . Since the cdc 4 gene product is required for SPB separation, the g1 structure may be defined by an association between chromosomes and spindle components . The folded chromosomes of the "start" mutants cdc 25 and cdc 28 are unstable at the restrictive temperature . In contrast to cdc 4, neither cdc 25 nor cdc 28 are able to enter the G0 stage in a normal manner, i.e., the g0 structure is unstable at the restrictive temperature . The inference is that both the cdc 25 and cdc 28 gene products are required for the functional integrity of the folded genome at both a stage early in G1 and in the pathway to G0.

Eur J Biochem, 1979 Jan 15, 93(2), 355 - 61
Purification and characterization of the hypoxanthine-guanine phosphoribosyltransferase from Saccharomyces cerevisiae; Schmidt R et al.; 1 . Hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) from Saccharomyces cerevisiae was purified 9400-fold by affinity chromatography giving rise to an electrophoretically homogeneous preparation . 2 . The molecular weight of the enzyme was determined by gel filtration with Sephadex G-100 and by sodium dodecylsulfate gel electrophoresis . Both methods reveal a molecular weight of 51,000 . 3 . The enzyme requires Mg2+ and has its pH optimum at 8.5 . 4 . Isoelectric focussing as well as gel electrophoresis of the purified extract reveals a single band which exhibits enzyme activity . The isoelectric point of the enzyme is 5.1 . 5 . The enzyme displays Michaelis-Menten kinetics with apparent Michaelis constants for hypoxanthine, guanine and phosphoribosylpyrophosphate of 23 microns, 18 microns, and 50 microns respectively.

Mol Gen Genet, 1979 Jan 11, 168(3), 299 - 308
Organization and expression of a two-gene cluster in the arginine biosynthesis of Saccharomyces cerevisiae; Minet M et al.; In Saccharomyces cerevisiae, argB and argC define two adjacent and complementing loci, with mutants defective in two consecutive steps of arginine biosynthesis: N-acetylglutamate kinase (AG-kinase) and N-acetylglutamyl-phosphate reductase (AGPreductase) . These enzymic activities are readily separated by ammonium sulfate fractionation or Sephadex G-200 chromatography . This suggests that each activity is carried in vivo by a different protein . The synthesis of the two enzymes is coordinately regulated, with an 85-fold difference in specific activities between fully repressed and fully derepressed cells . Missence mutations of the argB locus are defective in AGkinase only . Nonsense mutations in the argB locus are defective in both activities . Missense and nonsense mutations in the argC locus are defective in AGPreductase, with a few alleles also showing a reduced level of AGkinase . These data are best explained by assuming that argB and argC are two genes transcribed as a single messenger from argB to argC . This messenger produces in vivo two distinct proteins corresponding to the argB and argC gene products, either because translation can be initiated at the beginning of both genes, or because a large polypeptide is specifically cut in vivo to yield the gene products of argB and argC.

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