J Biol Chem, 1979 Jan 10, 254(1), 42 - 3 Sequence homologies of (guanosine + cytidine)-rich regions of mitochondrial DNA of Saccharomyces cerevisiae; Cosson J et al.; The nucleotide sequences of two distinct regions of mitochrondrial DNA of Saccharomyces cerevisiae are reported . The regions studied have a high content of G + C (45%) and contain closely spaced Hpa II and Hae III restriction sites . Both regions have sequences that are homologous over a lenght of 47 base-pairs . In addition, the two regions are highly palindromic . These data support certain aspects of the organization of mitochondrial DNA proposed by Prunell and Bernardi (Prunell, A., and Bernardi, G . (1977) J . Mol . Biol . 110, 53--74). Mol Gen Genet, 1979 Jan 5, 168(1), 101 - 9 Inserted sequence in the mitochondrial 23S ribosomal RNA gene of the yeast Saccharomyces cerevisiae; Faye G et al.; The sequence organization of the yeast mit-DNA region carrying the large ribosomal RNA gene and the polar locus omega was examined . Hybridization studies using rho- deletion mutants and electron microscopy of the heteroduplexes formed between 23S rRNA and the appropriate restriction fragments, lead to the conclusion that the 23S rRNA1 gene of the omega+ strains is split by an insertion sequence of 1,000-1,100 bp . In contrast, no detactable insertion was found in the 23S rRNA gene of the omega- strains . The size and the location of the insert found in the 23S rRNA gene of the omega+ strains appear to be identical to those of the sequence delta which had previously been found to characterize the difference (at the omega locus) between the mitDNA of the wild type strains carrying the omega+ or omega- alleles (Jacq et al., 1977). Mol Gen Genet, 1979 Jan 2, 167(3), 299 - 300 Allelism relationships between diuron-resistant, antimycin-resistant and funiculosin-resistant loci of the mitochondrial map in Saccharomyces cerevisiae; Colson AM et al.; Using allelism tests, two diuron (DIU1, DIU2), one funiculosin (FUN1), and two antimycin (ANA1, ANA2) resistance loci are resolved into two mitochondrial drug-resistant genetic loci . DIU1 is alelic to ANA2 and FUN1 . DIU2 is allelic to ANA1. Mol Gen Genet, 1979 Jan 2, 167(3), 279 - 86 Repair of MMS-induced DNA double-strand breaks in haploid cells of Saccharomyces cerevisiae, which requires the presence of a duplicate genome; Chlebowicz E et al.; The formation and repair of double-strand breaks induced in DNA by MMS was studied in haploid wild type and MMS-sensitive rad6 mutant strains of Saccharomyces cerevisiae with the use of the neutral and alkaline sucrose sedimentation technique . A similar decrease in average molecular weight of double-stranded DNA from 5--6 X 10(8) to 1--0.7 X 10(8) daltons was observed following treatment with 0.5% MMS in wild type and mutant strains . Incubation of cells after MMS treatment in a fresh drug-free growing medium resulted in repair of double-strand breaks in the wild type stain, but only in the exponential phase of growth . No repair of double-strand breaks was found when cells of the wild type strain were synchronized in G-1 phase by treatment with alpha factor, although DNA single-strand breaks were still efficiently repaired . Mutant rad6 which has a very low ability to repair MMS-induced single-strand breaks, did not repair double-strand breaks regardless of the phase of growth . These results suggest that (1) repair of double-strand breaks requires the ability for single-strand breaks repair, (2) rejoining of double-strand breaks requires the availability of two homologous DNA molecules, this strongly supports the recombinational model of DNA repair. Mol Gen Genet, 1979 Jan 2, 167(3), 243 - 50 Suppression of mitochondrially-determined resistance to chloramphenicol and paromomycin by nuclear genes in Saccharomyces cerevisiae; Waxman MF et al.; Phenotypic "revertants" of a drug resistant strain of Saccharomyces cerevisiae were induced by mutgenesis with manganese . Several of these drug sensitive mutants have been shown to result from mutations in the nuclear genome that cause phenotypic modification (suppression) of the mitochondrially-determined drug resistant genotype . Four mutants carrying a single recessive nuclear gene capable of modifying mitochondrial chloramphenicol resistance are described; these may be assigned to three complementation groups . Chloramphenicol resistant mutants mapping at five separate mitochondrial loci are described . At least two of the nuclear genes cause modification of mitochondrial chloramphenicol resistance determined by mutations at three of these loci, but the other two loci are apparently non-suppressible by these nuclear alleles . This indicates that these modifiers do not act by causing a general decrease in cellular or mitochondrial permeability to the drug . A single dominant nuclear modifier of mitochondrial paromomycin resistance has been identified . It is non-allelic to and does not interact with the genes modifying mitochondrial chloramphenicol resistance. Mol Gen Genet, 1979 Jan 2, 167(3), 301 - 8 Petite deletion map of the mitochondrial oxi3 region in Saccharomyces cerevisiae; Carignani G et al.; Fifty eight mitochondrial mutants (p + mit- mutants), all deficient in cytochrome oxidase activity and previously assigned to the genetic region oxi3 on the mitochondrial DNA, were mapped by the method of "petite deletion mapping" . This procedure resulted in the identification of at least twenty one different classes of oxi3 mutants, which could be arranged in a linear order . Moreover, it provided a set of twenty three p- petite mutants, each containing a differentially deleted mit DNA segment included in the oxi3 region . The two sets of mutants, p+ oxi3- and p- oxi3+, will be of interest for a further genetic and physical analysis of this mitochondrial DNA segment which spans over about ten thousand base pairs and controls the subunit I of cytochrome oxidase. Environ Mutagen, 1979, 1(1), 55 - 63 Mutagenicity of cross-links and monoadducts of furocoumarins (psoralen and angelicin) induced by 360-nm radiation in excision-repair-defective and radiation-insensitive strains of Saccharomyces cerevisiae; Grant EL et al.; The furocoumarin psoralen can form both monoadducts and cross-links with DNA when combined with 360-nm radiation, whereas the analog angelicin can form monoadducts only . Psoralen plus 360-nm radiation causes mutation induction with a slope of 2 (log-log plot) for a radiation-insensitive strain, whereas angelicin action with 360-nm radiation displays a slope of unity . For a radiation-sensitive mutant defective in the excision-repair pathway, the actions of both angelicin and psoralen plus 360-nm radiation exhibit one-target kinetics, but at higher exposures psoralen plus 360-nm radiation assumes a slope of 2 . The excision-repair-defective strain is considerably more sensitive to the furocoumarins plus 360-nm radiation than is the radiation-insensitive strain, both for killing and mutation induction . The simplest explanation for the data is that both cross-links and monoadducts, formed by furocoumarins with DNA when exposed to 360-nm radiation, are capable of inducing mutations, and that monoadducts are repaired 20 times more efficiently than cross-links by the excision-repair pathway. Z Allg Mikrobiol, 1979, 19(6), 411 - 4 {Different composition of the cell wall polysaccharides in Saccharomyces cerevisiae S288 and in an osmosis sensitive mutant}; Reuter G et al.; Determination of the polysaccharide contents and structural studies on the mannan by acetolysis and permethylation analysis shows an altered polysaccharide biosynthesis of the osmotic-sensitive mutant VY 1160 of Saccharomyces cerevisiae S 288 . The mutant contains more glucan, less mannan, and less alkali-soluble glycogen . Its mannan is characterized by more short side chains and less long side chains . Its main chain is 1 leads to 6-linked, but its side chains consist of more 1 leads to 3- than 1 leads to 2-linked mannose units. Z Allg Mikrobiol, 1979, 19(5), 357 - 62 Chitin structures of the cell walls of synchronously grown virgin cells of Saccharomyces cerevisiae; Vrsanska M et al.; The ability of a lytic beta-glucanase of Arthrobacter GJM-1 to dissolve cell walls of Saccharomyces cerevisiae with exception of the chitin-containing fraction was employed for the isolation of chitin-rich residues of the cell walls of synchronously growing populations of virgin cells . Electron microscopical examination of such wall residues isolated from cells at various stages of the budding cycle showed that the first phase of chitin deposition in the wall corresponds to the formation of an annular structure found as a part of the bud scar after cell division . The annular chitin-rich structure could not be isolated at cell cycle stages preceding the bud emergence and at earliest stages of bud development . The observations confirmed that the annular structure (chitin ring) formed during bud growth represents a major part of total chitin present in the bud scar after septum closure. Mol Gen Genet, 1979, 177(1), 139 - 43 Nuclear inheritance of resistance to antimycin A in Saccharomyces cerevisiae; Lucchini G et al.; A group of 30 independent mutants of Saccharomyces cerevisiae, resistant to the respiratory inhibitor antimycin A, was investigated from a genetical and biochemical point of view . All the mutants can be grouped into two nuclear loci: AMY1 maps on the VII chromosome, between leu 1 and trp 5; AMY2 is close to its centromere on either chromosome XVIII or XIX . Both genes do not affect mitochondrial structures or functions. Biochimie, 1979, 61(9), 1073 - 80 Analysis of large specific T1 oligonucleotides of 17S and 25S ribosomal RNAs from Saccharomyces cerevisiae; Eladari ME et al.; The primary structure of 17S and 25S ribosomal RNAs from Saccharomyces cerevisiae has been analysed by two-dimensional fractionation of T1 oligonucleotides . This method consists of an electrophoresis at pH 3.5 followed by a homochromatography on DEAE-cellulose plates . After the second dimension, the large T1 oligonucleotides were hydrolyzed by pancreatic RNAse, followed by alkaline hydrolysis of the pancreatic products . By fractionating a mixture of tritiated HeLa cell ribosomal RNAs and 32 P yeast cell ribosomal RNAs, two autoradiographs were obtained; one corresponding to the 32P labelled material and the other to the tritiated labelled material . By superposition of the two autoradiographs, the mobility of the various T1 oligonucleotides can be accurately compared and it is shown that yeast 17S rRNA and human 18S rRNA have in common 5 large oligonucleotides and that yeast 25S rRNA and human 28S rRNA have 4 identical oligonucleotides. Folia Microbiol (Praha), 1979, 24(3), 240 - 6 Transport of manganese into Saccharomyces cerevisiae; Okorokov LA et al.; The uptake of Mn2+ by Saccharomyces cerevisiae at the expense of endogenous sources of energy depends on the stage of culture development and is maximum in the middle of the exponential phase . The ability of cells to take up Mn+ is related to the content of intracellular potassium at all stages of growth, to the content of ATP during the exponential phase and it is not related to the content of inorganic polyphosphates . The uptake is inhibited by oligomycin (25 microgram/ml) by 50-85% and under anaerobic conditions by 10-50%, depending on the stage of growth, indicating the role of aerobic phosphorylation in the process . The uptake of Mn+ is apparently associated with a hydrolysis of low-molecular weight polyphosphates and ATP, as well as with the exit of K+ from cells. Nucleic Acids Res, 1979, 6(6), 2133 - 50 Propagation of restriction fragments from the mitochondrial DNA of Saccharomyces cerevisiae in E . coli by means of plasmid vectors; Berg PE et al.; Some of the EcoRI fragments of yeast (Saccharomyces cerevisiae) mitochondrial DNA were cloned into E . coli using plasmid pMB9 . The five smallest fragments in molecular weight appeared to be preferentially retained by E coli; partial fragments derived from larger mitochondrial DNA fragments were also found . One of the fragments, R7 (2.4 kb), may contain the OII gene . Cloned R7 DNA was stable under a variety of growth conditions, but showed some changes in molecular weight after transfer to different E . coli strains . Fragment R7 is transcribed in minicells, producing RNA that hybridizes specifically to mitochondrial DNA . Both DNA strands are transcribed, in contrast to the asymmetric transcription found in mitochondria . No new polypeptides were observed in minicells containing cloned fragment 7. J Gen Microbiol, 1979 Jan, 110(1), 185 - 91 Effects of phosphate limitation of growth on the cell-wall and lipid composition of Saccharomyces cerevisiae; Ramsay AM et al.; The phosphorus content of phosphate-limited Saccharomyces cerevisiae was only 71% of that of non-limited yeast . Walls prepared from phosphate-limited cells contained slightly less phosphorus than control walls . No evidence was obtained for the presence in these walls of uronic acid or succinyl residues . The carbohydrate content of walls of phosphate-limited yeast was less than that of non-limited walls, and this was reflected in a decreased glucan content . There was only a slight decrease in glucosamine content while the protein content increased . The major change in the lipid composition of phosphate-limited yeast was a decrease in both sterol esters and triacylglycerols . There was a decrease in total lipid content, but increased production of phosphatidylethanolamine and phosphatidylcholine . The phosphatidylserine content was decreased . These results suggest that there are fewer intracellular low-density vesicles in phosphate-limited yeast. Genetics, 1979 Jan, 91(1), 19 - 33 Genetic analysis of multiple drug cross resistance in Saccharomyces cerevisiae: a nuclear-mitochondrial gene interaction; Cohen JD et al.; A mutant of the yeast Saccharomyces cerevisiae, cross resistant to several antibiotics, was isolated in our laboratory and subjected to genetic analysis . Tetrad analysis of diploids obtained from crosses between the resistant mutant and a sensitive wild-type strain suggest that the multiple resistance to the five agents, oligomycin (OLI), rhodamine 6G (RHG), tetracycline (TCN), chloramphenicol (CAP) and cycloheximide (CHX) is determined by a single nuclear gene, ant1, and requires several cytoplasmic genes for expression of resistance to oligomycin, rhodamine 6G and tetracycline . --Vegetatively growing diploid clones derived from the cross ant1 {RHO+} X +{RHO+} show mitotic segregation of two phenotypic classes for the drugs OLI, RHG TCN . Diploids derived from the two reciprocal crosses, ant1 {RHO+} X +{RHO-} and ant1 {RHO-} X +{RHO+}, fail to exhibit mitotic segregation . These results are consistent with our hypothesis concerning the involvement of cytoplasmic loci . They suggest, in addition, that these loci are associated with mitochondrial DNA (mtDNA) . --Evidence for this association is provided by the demonstration of genetic linkage between the cytoplasmic loci involved in the interaction, RHG-1, TCN-1 and OLI-5, and two well-characterized mitochondrial loci, ERY and CAP . --We have mapped the nuclear ant1 locus 3.3 cM from the centromere-linked gene, leu1, on the same side of the centromere of chromosome VII as leu1 . --In the light of these findings, we discuss the claims made by several authors of the episomal nature of mutations similar to the one described here, as well as of the possible involvement of yeast 2 mu DNA in such mutations. J Bacteriol, 1979 Jan, 137(1), 1 - 5 Regulation of cell size in the yeast Saccharomyces cerevisiae; Johnston GC et al.; For cells of the yeast Saccharomyces cerevisiae, the size at initiation of budding is proportional to growth rate for rates from 0.33 to 0.23 h-1 . At growth rates lower than 0.23 h-1, cells displayed a minimum cell size at bud initiation independent of growth rate . Regardless of growth rate, cells displayed an increase in volume each time budding was initiated . When abnormally small cells, produced by starvation for nitrogen, were placed in fresh medium containing nitrogen but with different carbon sources, they did not initiate budding until they had grown to the critical size characteristic of that medium . Moreover, when cells were shifted from a medium supporting a low growth rate and small size at bud initiation to a medium supporting a higher growth rate and larger size at bud initiation, there was a transient accumulation of cells within G1 . These results suggest that yeast cells are able to initiate cell division at different cell sizes and that regulation of cell size occurs within G1. Proc Natl Acad Sci U S A, 1979 Jan, 76(1), 131 - 5 Assembly of the mitochondrial membrane system: partial sequence of a mitochondrial ATPase gene in Saccharomyces cerevisiae; Macino G et al.; The nucleotide sequence of mitochondrial DNA of a cytoplasmic "petite" mutant of Saccharomyces cerevisiae is reported . The DNA has a repeat length of 1060 base pairs and contains a genetic marker (oli-1) for the ATPase proteolipid . The nucleotide sequence reveals the presence of part of the structural gene of the subunit-9 proteolipid of the ATPase complex and an extended A+T-rich region adjacent to the carboxyl-terminal end of the gene . The structural gene sequence agrees with the primary structure of the protein . These studies point out the feasibility of using the DNA of appropriately marked "petite" mutants to obtain the sequence of mitochondrial genes. Mol Gen Genet, 1979, 172(3), 249 - 58 Decreased UV mutagenesis in cdc8, a DNA replication mutant of Saccharomyces cerevisiae; Prakash L et al.; A DNA replication mutant of yeast, cdc8, was found to decrease UV-induced reversion of lys2-1, arg4-17, tyr1 and ura1 . This effect was observed with all three alleles of cdc8 tested . Survival curves obtained following UV irradiation in cdc8 rad double mutants show that cdc8 is epistatic to rad6, as well as to rad1; cdc8 rad51 double mutants seem to be more sensitive than the single mutants . Since UV-induced reversion in cdc8 rad1 and cdc8 rad51 double mutants is like that of the cdc8 single mutants, we conclude that CDC8 plays a direct role in error-prone repair . To test whether CDC8 codes for a DNA polymerase, we have purified both DNA polymerase I and DNA polymerase II from cdc8 and CDC+ cells . The purified DNA polymerases from cdc8 were no more heat labile than those from CDC+, suggesting that CDC8 is not a structural gene for either enzyme. J Bacteriol, 1979 Jan, 137(1), 179 - 84 Effects of aeration on formation and localization of the acetyl coenzyme A synthetases of Saccharomyces cerevisiae; Klein HP et al.; A method is shown to be effective over a wide range of enzyme ratios for the simultaneous detection of the two isoenzymes of acetyl coenzyme A synthetase {acetate:coenzyme A ligase (AMP-forming); EC 6.2.1.1} in homogenates and cellular fractions of Saccharomyces cerevisiae . When this method was used, it was found that cells grown under anaerobic conditions contained only one variety of this enzyme, designated the nonaerobic synthetase, whereas cells grown with vigorous aeration contained principally the other, aerobic, synthetase . In cells grown as standing cultures (i.e., semi-aerobically), both enzymes were present and were found mainly in the extramitochondrial material of homogenates . When anaerobic cultures were aerated, the amount of aerobic enzyme increased steadily over a 24-h period, so that at the end of this time, aerated cells contained predominantly aerobic enzyme . During this same period, the amount of nonaerobic enzyme decreased . The percentage of aerobic enzyme that sedimented with the mitochondria increased steadily during this period of aeration, so that, at the end of 24 h of aeration, essentially all of the aerobic enzyme sedimented with the mitochondria . The nonaerobic enzyme was never found in this cellular compartment. Radiat Environ Biophys, 1978 Dec 22, 15(4), 379 - 85 Induction of mutations by photodynamic action of thiopyronine in Saccharomyces cerevisiae; Kenter D et al.; The induction of cytoplasmic and nuclear mutations by the photodynamic action of thiopyronine is demonstrated in a haploid strain of Saccharomyces cerevisiae that has been isolated as a photodynamic sensitive mutant . No significant increase in corresponding mutation frequencies could be observed in a strain resistant to photodynamic inactivation by thiopyronine. Biochim Biophys Acta, 1978 Dec 22, 531(3), 301 - 7 Delta14-sterol reductase in Saccharomyces cerevisiae; Bottema CK et al.; An in vitro assay for delta14-sterol reductase from yeast was developed, using ergosta-8,14-dien-3beta-ol as the substrate . The kinetics and localization of the enzyme were examined . The inhibition of the enzyme by the antimycotic agent, 15-azasterol, was verified. Chromosoma, 1978 Dec 21, 70(1), 109 - 30 Meiotic effects of DNA-defective cell division cycle mutations of Saccharomyces cerevisiae; Schild D et al.; The meiotic effects of several cell division cycle (cdc) mutations of Saccharomyces cerevisiae have been investigated by electron microscopy and by genetic and biochemical methods . Diploid strains homozygous for cdc mutations known to confer defects on vegetative DNA synthesis were subjected to restrictive conditions during meiosis . Electron microscopy revealed that all four mutants were conditionally arrested in meiosis after duplication of the spindle pole bodies but before spindle formation for the first meiotic division . None of these mutants became committed to a recombination or contained synaptonemal complex at the meiotic arrest.--The mutants differed in their ability to undergo premeiotic DNA synthesis under restrictive conditions . Both cdc8 and cdc21, which are defective in the propagation of vegetative DNA synthesis, also failed to undergo premeiotic DNA synthesis . The arrest of these mutants at the stage before meiosis I spindle formation could be attributed to the failure of DNA synthesis because inhibition of synthesis by hydroxyurea also caused arrest at this stage.--Premeiotic DNA synthesis occurred before the arrest of cdc7, which is defective in the initiation of vegetative DNA synthesis, and of cdc2, which synthesizes vegetative DNA but does so defectively . The meiotic arrest of cdc7 homozygotes was partially reversible . Even if further semiconservative DNA replication was inhibited by the addition of hydroxyurea, released cells rapidly underwent commitment to recombination and formation of synaptonemal complexes . The cdc7 homozygote is therefore reversibly arrested in meiosis after DNA replication, whereas vegetative cultures have previously been shown to be defective only in the initation of DNA synthesis. Can J Microbiol, 1978 Dec, 24(12), 1614 - 5 Sporulation in single-spore isolates from amitrole-induced multispored asci of Saccharomyces cerevisiae; Ashraf M et al.; Amitrole treatment causes multispored ascus production by cells of a yeast strain whose asci normally contain two diploid spores . Single spores were isolated from asci containing two to eight spores and their ability to germinate was determined . Cells in colonies grown from single spores sporulated in the same manner as the parent strain indicating that amitrole had not induced meiotic division in the developing asci. J Gen Microbiol, 1978 Dec, 109(2), 205 - 13 The use of step enzymes as markers during meiosis and ascospore formation in Saccharomyces cerevisiae; Matur A et al.; The activities of ornithine aminotransferase, sucrase and acid and alkaline phosphatases have been studied throughout sporulation in Saccharomyces cerevisiae . The same enzymes were monitored during synchronous vegetative growth . Each of these enzymes has been demonstrated to increase in a 'step' manner during both growth and sporulation . Alkaline phosphatase increased in a two-step manner whereas the others increased in a single step . The times of increase of these enzymes formed a similar sequence during both sporulation and growth . It has been proposed that these enzymes are under a common mechanism of control during growth and sporulation and that the sequence of enzyme appearance may be used as markers of the sporulation process. Proc Natl Acad Sci U S A, 1978 Dec, 75(12), 6172 - 6 Control of expression of a cloned yeast (Saccharomyces cerevisiae) gene (trp5) by a bacterial insertion element (IS2); Walz A et al.; A hybrid ColE1 plasmid {pYe(trp5)1}, containing a yeast DNA segment that complements auxotrophic point mutations and deletions in the Escherichia coli tryptophan synthetase gene (trpAB), has been isolated . Expression of the yeast tryptophan synthetase activity from the cloned yeast gene (trp5) is relatively inefficient in E . coli, as measured by growth rates of trpAB/pYe(trp5)1 strains on minimal media lacking tryptophan and by enzyme assays . Faster growing variants occur spontaneously at a frequency of one in 10(4)--10(5) cells plated and produce higher levels of the yeast enzyme . Plasmid DNA {pYe(trp5)2} from one of these variants was shown to contain a DNA insertion (1.3 kilobase pairs) in the cloned yeast DNA segment in relatively close proximity to the trp5 gene . This DNA insert was identified as a bacterial IS2 element, which carries a promoter for RNA transcription when inserted in the proper orientation . The spontaneous integration of a bacterial DNA insertion element into cloned eukaryotic DNA can result in more efficient expression of the foreign gene. Proc Natl Acad Sci U S A, 1978 Dec, 75(12), 6083 - 7 Methionine analogs and cell division regulation in the yeast Saccharomyces cerevisiae; Singer RA et al.; Methionine analogs such as ethionine, selenomethionine, and trifluoromethionine all arrest growth and division of the yeast Saccharomyces cerevisiae . One analog, ethionine, caused cells of the yeast to arrest specifically within G1; reciprocal shift experiments showed that ethionine and alpha-factor arrested cells at the same step ("start") . The major effect of ethionine on synthesis of macromolecules was to reduce both the rate of appearance of 35S ribosomal precursor RNA and the rate of production of mature rRNA . Synthesis of protein was relatively unaffected by ethionine . Selenomethionine and trifluoromethionine caused cells to arrest randomly in the cell division cycle . Although treatment of cells with either selenomethionine or trifluoromethionine also reduced the rate of total RNA synthesis, each of these analogs had other effects that presumably prohibited completion of the cell cycle . We propose that the rate of rRNA production is an important regulatory event in the cell cycle. J Bacteriol, 1978 Dec, 136(3), 1002 - 7 Chromosomal superkiller mutants of Saccharomyces cerevisiae; Toh-E A et al.; Yeast strains carrying a 1.5 X 10(6)-dalton double-stranded RNA in virus-like particles secrete a protein toxin which is lethal to strains not carrying this species of double-stranded RNA . We find that recessive mutations in any of four chromosomal genes result in the superkiller phenotype, i.e., increased secretion of killer toxin activity by strains carrying the killer genome . These genes are designated ski1 through ski4 (for superkiller), ski3 and ski4 are located on chromosome XIV, and ski1 is on chromosome VII . A ski1 mutation results in a decreased rate of cell growth . The kex1 and kex2 mutations are epistatic to each ski mutation. Mol Cell Biochem, 1978 Nov 30, 22(1), 39 - 49 Kinetic characterization of plasma membrane ATPase from Saccharomyces cerevisiae; Ahlers J et al.; 1 . Plasma membrane preparations have been isolated from spheroplasts of Saccharomyces cerevisiae, strain R XII, via lysis and subsequent differential centrifugation . These preparations are almost devoid of mitochondrial contamination . 2 . The plasma membrane ATPase is fairly stable when refrigerated, but loses activity at 8 degrees C and above . Below pH 5.6 the ATPase is irreversibly inactivated . The enzyme also splits GTP and ITP, although to a lesser extent . 3 . Mg2+-ions are essential as part of the reactive substrate, MgATP, and furthermore they activate the ATPase . Optimal conditions depend on substrate concentration . When the concentration of free Mg2+ ions exceeds about 0.1 mM, competitive inhibition occurs . 4 . In the range of pH 5.6-9.2 two functional groups dissociate . One, with pKb = 8.1 +/- 0.1 participated in substrate binding and another one with pKb' = 8.1 +/- 0.1 is involved in substrate splitting . 5 . The experiments with group-specific inhibitors suggest that an alpha-amino group and a sulfhydryl residue are involved in substrate binding and conversion . Furthermore, imidazole, tryptophan and carboxyl residues may be important for the catalytic process. Mol Gen Genet, 1978 Nov 29, 167(2), 177 - 84 Detection of aberrant nuclear DNA metabolism in a conditional mutant of Saccharomyces cerevisiae; Rubin BY et al.; A single recessive nuclear gene mutation has been isolated from strain 123.1C of Saccharomyces cerevisiae which appears to be conditionally deficient in nuclear DNA metabolism . Growth of the mutant strain at the elevated temperature of 36 degree C results in rapid loss of cell viability . However, no apparent reduction in the rate of radioisotope incorporation into DNA was detected during this period . When haploid cells carrying this temperature sensitive lesion were exposed to the restrictive temperature for varying lengths of time, returned to the permissive temperature, mated with a non-temperature sensitive strain and then the resulting diploids made to undergo meiosis, a greatly reduced number of viable spores were produced . Genetic analysis of the viable spores produced by these diploids has revealed aberrant auxotrophic marker segregation patterns . Thus, these results suggest that the mutated gene hardbored in this strain plays a vital role in the metabolism of the nuclear genome. Mol Gen Genet, 1978 Nov 29, 167(2), 139 - 45 Endonuclease alpha from Saccharomyces cerevisiae shows increased activity on ultraviolet irradiated native DNA; Bryant DW et al.; Endonuclease alpha isolated from the nucleus of the yeast Saccharomyces cerevisiae is a DNA endonuclease which has been shown to act preferentially on denatured T7 DNA . The purified enzyme is more active with UV-irradiated native T7 DNA than with unirradiated substrate . The relation between damage, measured by pyrimidine dimer concentration, and excess endonuclease activity is most readily explained by local denaturation caused by presence of pyrimidine dimers . When three radiation sensitive mutants of yeast were tested for the level of endonuclease alpha present, none were found lacking the enzyme . However, nuclei of strain rad 1-1, a mutant that may be defective in heteroduplex repair as well as excision repair, were found to contain reduced levels of the endonuclease . The enzyme isolated from this strain had less than one half the specific activity of similar preparations from wild type yeast. Biochim Biophys Acta, 1978 Nov 21, 521(1), 342 - 51 Regulation of acid phosphatase synthesis in Saccharomyces cerevisiae; Elorza MV et al.; In Saccharomyces cerevisiae-136ts (Hutchison, H.T., Hartwell, L.H . and McLaughlin, C.S . (1969) J . Bacteriol . 99, 807--814) derepressed acid phosphatase was almost exclusively located outside the permeability barrier . Only a minor part of the activity was associated with the protoplasts; about half of it (48%) in the soluble fraction, the rest bound to the internal (45%) and plasma (7%) membranes . The activity found in the membranes of derepressed cells decreased by 30--40% after addition of inorganic phosphate or cycloheximide suggesting that this activity is the precursor of the external enzyme . The alkaline phosphatase activity level could not be modified by changes in the concentration of inorganic phosphate . Acid phosphatase was not synthesized if the cells were transferred to a low phosphate medium at the moment of incubation at 37 degrees C or in the presence of cycloheximide at 23 degrees C . The data suggested that enzyme formation is the result of the transcription and translation of a specific gene(s) and not the activation of a proenzyme . Inorganic phosphate did not inhibit the translation of mRNA though it may act at the level of the transcription. Mol Gen Genet, 1978 Nov 9, 166(3), 251 - 8 The regulation of urea amidolyase of Saccharomyces cerevisiae: mating type influence on a constitutivity mutation acting in cis; Lemoine Y et al.; Constitutivity for the synthesis of the urea amidolyase bienzymatic complex is obtained by durOh mutations located in the regulatory genetic region adjacent to the dur1, dur2 gene cluster . The durOh mutations act only in cis and are a new case of cis effect strongly cancelled in alpha/a diploid, similar to cargA+Oh mutation shown previously to lead to arginase constitutivity . Illegitimate diploids do not show such a cancellation of constitutivity . The constitutivity produced by durOh mutation comprises the process of induction and the release of the glutamine effect . It does not impair the NH+4 effect. Eur J Biochem, 1978 Nov 2, 91(1), 255 - 61 Circular-dichroism studies of the cytochrome b-c1 complex of Saccharomyces cerevisiae; Reed J et al.; 1 . Circular dichroism studies on the Soret region of the cytochrome b-c1 complex of yeast reveal a change in the dichroism of cytochrome c1 depending on the redox state of cytochrome b, indicating a conformational interaction between both cytochromes . 2 . This interaction is not influenced by binding of the inhibitor antimycin A to the complex, so that the interaction does not appear to be involved in the mechanism of electron transport through the complex . 3 . Antimycin A binding causes a complex set of changes in the CD spectrum of the complex, which can be attributed to a severe and specific distortion of the environment of the chromophore of cytochrome b. Biol Bull Acad Sci USSR, 1978 Nov-Dec, 5(6), 696 - 703 Physiological and biochemical properties and morphology of Saccharomyces cerevisiae VKMu-488 cells incorporated into polyacrylamide gel; Koshcheenko KA et al.; The enzymatic activity, viability, respiratory activity, and ultrastructural changes in saccharomyces cerevisiae VKMu-488 cells, which carry out the stereospecific 17 beta-reduction of methyl esters, was studied . The 17 beta-hydroxysteroid dehydrogenase activity of yeasts in gel is four times lower than that of free cells and is unstable . The decrease in the viability and respiratory activity immediately after immobilization, the disturbance in the ultrastructure of the cells in gel along with the progressive lysis of the cells in the course of the transformation indicate that polymerization has a stressful effect on this culture . It was found that the immobilized yeasts can grow on the surface of the gel in the presence and absence of nutrient medium . A single incubation of granules containing cells in nutrient medium greatly stabilizes the original activity of the immobilized cells . The activation and stabilization of the activity are probably due to the participation of a heterogeneous population in the transformation: the original population incorporated into the gel and the new population which grows in the gel after immobilization as well as to the stability of the ultrastructural organization of this mixed population in the course of repeated transformations of secoketone. Nucleic Acids Res, 1978 Nov, 5(11), 4329 - 42 Isopentenyladenosine deficient tRNA from an antisuppressor mutant of Saccharomyces cerevisiae; Laten H et al.; We have isolated a mutant of Saccharomyces cerevisiae that contains 1.5% of the normal tRNA complement of isopentenyladenosine (i6A) . The mutant was characterized by the reduction in efficiency of a tyrosine inserting UAA nonsense suppressor . The chromatographic profiles of tRNATyr and tRNASer on benzoylated DEAE-cellulose are consistent with the loss of i6A by these species . Transfer RNA from the mutant exhibits 6.5% of the cytokinin biological activity expected for yeast tRNA . Transfer RNAs from the mutant that normally contain i6A accept the same levels of amino acids in vitro as the fully modified species . With the exception of i6A, the level of modified bases in unfractionated tRNA from the mutant appears to be normal . The loss of i6A apparently affects tRNA's role in protein synthesis at a step subsequent to aminoacylation. Genetika, 1978 Nov, 14(11), 1884 - 91 {Reparation after the action of 8-methoxypsoralen and light (lambda=365 nm) on radiosensitive mutants of Saccharomyces cerevisiae yeasts}; Fedorova IV; The method of repeated irradiation allowed to study kinetics of excision of mono-adducts induced by 8-methoxypsoralen (8-MOP) plus light (lambda=365 nm) in DNA of UV-sensitive mutants rad4 and rad15 and X-ray sensitive mutants rad54, xrs2, xrs4 . The survival of the mutant rad4 was not practically increased after incubation in complete liquid medium for 3 hours at 28 degrees C before the repeated irradiation . These data suggest that the mutant rad4 is characterized by nearly complete absence of the mono-adduct excision . The survival of mutants rad15 and rad54 in the same environment was increased less effectively than the survival of the control radioresistant strain, but the mutants xrs2 and xrs4 did not differ from the control strain . Possible causes of differences in survival between radiosensitive strains are discussed . The increased sensitivity of the excision defective strain (rad4) and of the postreplicative recombination defective strains (xrs2, xrs4, rad54) to the lethal effect of 8-MOP plus light (lambda=365 nm) suggests that two systems of reparation take part in the removal of photoproducts induced by 8-MOP in DNA of yeast cells. J Bacteriol, 1978 Nov, 136(2), 531 - 7 Metabolic interconversion of free sterols and steryl esters in Saccharomyces cerevisiae; Taylor FR et al.; The interconversion of free and esterified sterols was followed radioisotopically with {U-14C}acetate and {methyl-14C}methionine . In pulse-chase experiments, radioactivity first appeared mainly in unesterified sterols in exponential-phase cells . Within one generation time, the label equilibrated between the free and esterified sterol pools and subsequently accumulated in steryl esters in stationary-phase cells . When the sterol pools were prelabeled by growing cells aerobically to the stationary phase and the cells were diluted into unlabeled medium, the prelabeled steryl esters returned to the free sterol form under several conditions . (i) During aerobic growth, the prelabeled sterols decreased from 80% to 45% esters in the early exponential phase and then returned to 80% esters as the culture reached the stationary phase . (ii) Under anaerobic conditions, the percentage of prelabeled steryl esters declined continuously . When growth stopped, only 15% of the sterols remained esterified . (iii) In the presence of an inhibitor of sterol biosynthesis, which causes accumulation of a precursor to ergosterol, prelabeled sterols decreased to 40% steryl esters while the precursor was found preferentially in the esterified form . These results indicate that the bulk of the free sterol and steryl ester pools are freely interconvertible, with the steryl esters serving as a supply of free sterols . Furthermore, there is an active cellular control over what types of sterol are found in the free and esterified sterol pools. Mol Gen Genet, 1978 Oct 30, 166(2), 193 - 209 The non-reciprocality of organelle gene recombination in Chlamydomonas reinhardtii and Saccharomyces cerevisiae: some new observations and a restatement of some old problems; Van Winkle-Swift KP et al.; Organelle recombinant genotype frequencies, derived from analysis of individual mitotic zygote clones of Chlamydomonas reinhardtii and Saccharomyces cerevisiae, were subjected to two types of statistical tests in an attempt to detect the occurrence of reciprocal recombination: (i) calculation of correlation coefficients for the frequencies of two recombinant genotypes (reciprocal or non-reciprocal pairs) within individual zygote clones, and (ii) application of the chi-square test for independence to the frequencies of zygotes yielding one or the other, neither, or both of a given recombinant pair . Applying test (i), the strongest correlations are found for non-reciprocal rather than reciprocal pairs . When the data are analyzed by method (ii), some reciprocal as well as non-reciprocal pairs appear to be produced concurrently in zygote clones . However, such deviations from independence are greatest for non-reciprocal pairs . These tests yield comparable results for yeast mitochondrial and Chlamydomonas chloroplast gene recombination, and provide no convincing evidence for reciprocal genetic exchange . Explanations for the observed lack of reciprocality are discussed with reference both to our present understanding of the molecular events responsible for genetic recombination, and to the problems which may be unique to the analysis of organelle gene recombination. Mol Gen Genet, 1978 Oct 25, 166(1), 91 - 6 Comparison of sensitivity and liquid holding recovery in rad mutants of Saccharomyces cerevisiae inactivated by UV and DEB; Zuk J et al.; Twenty one UV-sensitive rad mutants were tested for their sensitivity towards DEB . All mutants were more sensitive to this treatment than the wild type . Seven mutants were classified as supersensitive to DEB (rad 1-1, 2,3, 6, 15 and 18-2), while only rad2 and rad3 can be classified as supersensitive to UV . For all mutants ability for liquid holding recovery (LHR) after UV and DEB was compared . Mutants rad 1-1, 3, 5, 6, 9 and 11 differ in their response to LH after the two treatments . Survival of rad1-1 and rad3 increases signficantly during LH after DEB but not after UV exposure . In contrast rad5, 6, 11, and 22 show marked LHR after UV but no increase of survival after DEB treatment. Proc Natl Acad Sci U S A, 1978 Oct, 75(10), 4962 - 6 Identification of tubulin from the yeast Saccharomyces cerevisiae; Baum P et al.; A tubulin-like protein was identified in the lower eukaryote Saccharomyces cerevisiae . The following criteria were used: (i) copolymerization of the 35S-labeled yeast protein with porcine brain tubulin; (ii) immunoprecipitation of the 35S-labeled yeast protein with antiflagellar tubulin antibody; (iii) the presence of the yeast protein as a constituent of isolated yeast nuclei; and (iv) splitting of the yeast protein in a gel electrophoretic system containing sodium dodecyl sulfate that resolved the alpha- and beta-tubulin chains from other sources . This protein did not appear to have significant affinity for the plant alkaloid, Colcemid. J Bacteriol, 1978 Oct, 136(1), 55 - 62 Effect of mutation in the aromatic amino acid pathway on sporulation of Saccharomyces cerevisiae; Lucchini G et al.; Mutations in ARO1 and ARO2 genes coding for enzymes involved in the common part of the aromatic amino acid pathway completely block the sporulation of Saccharomyces cerevisiae when in a homozygous state, whereas mutations in all the other genes of the same pathway do not . This effect is not due to the lack of any intermediate metabolite but rather to the accumulation of a metabolite preceding chorismic acid . Shikimic acid or one of its precursors was identified as the possible inhibitor . The presence of the three aromatic amino acids in the sporulation medium restores the ability to undergo meiosis . This seems not to be due to a feedback inhibition of the first enzymes of the pathway but rather to a competition between aromatic amino acids and the inhibitor on a site specific for the meiotic process . The inhibition of sporulation seems to occur at a very early step in meiosis, as indicated by the lack of premeiotic DNA synthesis in aro1 and aro2 mutants. J Bacteriol, 1978 Oct, 136(1), 318 - 23 Altered nuclear pore diameters in G1-arrested cells of the yeast Saccharomyces cerevisiae; Willison JH et al.; Nuclear pores in cells of the yeast Saccharomyces cerevisiae were examined by using the freeze-fracture technique . Nuclear pore diameters in actively growing cells appear to be exclusively of the normal diameter (75 to 115 nm), whereas some pore diameters in abnormally small G1-arrested cells produced by nitrogen starvation are unusually wide (120 to 160 nm) . There may be a correlation between nuclear pore size and nuclear envelope size, the larger pores tending to occur in the smaller envelopes . The finding suggests that nuclear pore diameter may not function in regulating the flow of informational molecules from nucleus to cytoplasm, but may be implicated in regulating the flow of substrates into the nucleus. J Bacteriol, 1978 Oct, 136(1), 234 - 46 Control of vacuole permeability and protein degradation by the cell cycle arrest signal in Saccharomyces cerevisiae; Sumrada R et al.; Saccharomyces cerevisiae responds to deperivation of nutrients by arresting cell division at the unbudded G1 stage . Cells situated outside of G1 at the time of deperivation complete the cell cycle before arresting . This prompted an investigation of the source of nutrients used by these cells to complete division and the mechanisms controlling their availability . We found a close correlation between accumulation of unbudded cells and loss of previously formed allophanate hydrolase activity after nutrient starvation . These losses were not specific to the allantoin, system since they have been observed for a number of other enzymes and also when cellular protein levels were monitored with {3H}leucine . Loss of hydrolase activity was also observed when protein synthesis was inhibited either by addition of inhibitors or loss of the prtl gene product . We found that onset of nutrient starvation brought about release of large quantities of arginine and allantoin normally sequestered in the cell vacuole . Treatment of a cells with alpha-factor resulted in both the release of allantoin and arginine from the cell vacuole and the onset of intracellular protein degradation . These effects were not observed when either alpha cells or a/alpha diploid strains were treated with alpha-factor . These data suggest that release of vacuolar constitutents and protein turnover may be regulated by the G1 arrest signal. J Bacteriol, 1978 Oct, 136(1), 142 - 7 Isolation and characterization of an actinomycin D-sensitive mutant of Saccharomyces cerevisiae; Gorenstein C et al.; A single mutation in Saccharomyces cerevisiae conferred sensitivity to low concentrations of actinomycin D . Treatment with actinomycin D preferentially inhibited synthesis of rRNA's . Residual rRNA synthesized was processed normally . Total protein synthesis and inducibility of the enzyme maltase were relatively unaffected at concentrations of actinomycin D which severely inhibited rRNA synthesis. Appl Environ Microbiol, 1978 Oct, 36(4), 615 - 7 Flow microfluorometry study of diauxic batch growth of Saccharomyces cerevisiae; Gilbert MF et al.; Flow microfluorometry reveals complex changes in types and relative numbers of different Saccharomyces cerevisiae cell forms during glucose-limited diauxic batch growth. Mol Gen Genet, 1978 Sep 8, 164(3), 275 - 83 Catabolic synergism: a cooperation between the availability of substrate and the need for nitrogen in the regulation of arginine catabolism in Saccharomyces cerevisiae; Dubois EL et al.; The simultaneity of the presence of substrate (inducer) and the absence of a better nitrogen nutrient causes a strong cooperative effect (catabolic synergism) on arginase production . This effect is shown to operate by a specific mechanism . carg A+ 0h mutation (Dubois et al., 1978) identifies an element of this process located near the arginase structural gene and acting in cis . This mutation produces constitutivity for synergism in addition to constitutivity for induction (this last effect is produced alone by cargA +0- operator constitutive mutation) . The receptor of the signal for the presence of substrate is the same as for induction . cargA + 0h mutation allows to make further distinction between the promotion of arginase synthesis caused by nitrogen limitation and nitrogen starvation. J Toxicol Environ Health, 1978 Sep-Nov, 4(5-6), 913 - 7 Toxic and genetic effects of fuel oil photoproducts and three hydroperoxides in Saccharomyces cerevisiae; Callen DF et al.; Phototransformation of no . 2 fuel oil by UV irradiation at wavelengths designed to simulate sunlight resulted in the formation of products toxic to the yeast Saccharomyces cerevisiae . Increasing the time of irradiation of the fuel oil samples increased the toxicity . Fuel oil that had been irradiated for 12 or 24 h was convertagenic to the yeast strain D4 . The toxicity and genetic activity of these samples could be removed by treatment with thiacyclohexane . It is thought that hydroperoxides are the primary photoproducts responsible for these biological effects . Of three hydroperoxides tested, tert-butyl was convertagenic and cumene and tetralin were not . However, all three hydroperoxides were toxic to yeast. Mutat Res, 1978 Sep, 58(1), 99 - 101 Induction of gene conversion in Saccharomyces cerevisiae by the nitrofuran derivative furylfuramide (AF-2); Murthy MS et al.; The nitrofuran derivative furylfuramide (AF-2) is known to be both mutagenic and carcinogenic in a number of test systems . In this report we show that AF-2 can also induce gene conversion in diploid yeast in a manner dependent on both duration and concentration of treatment. Mutat Res, 1978 Sep, 51(3), 327 - 46 Cell-cycle variation in the induction of lethality and mitotic recombination after treatment with UV and nitrous acid in the yeast, Saccharomyces cerevisiae; Davies PJ et al.; Exponentially growing yeast cultures separated into discrete periods of the cell cycle by zonal rotor centrifugation show cyclic variation in both UV and nitrous acid induced cell lethality, mitotic gene conversion and mitotic crossing-over . Maximum cell survival after UV treatment was observed in the S and G2 phases of the cell cycle at a time when UV induction of both types of mitotic recombination was at a minimum . In contrast, cell inactivation by the chemical mutagen nitrous acid showed a single discrete period of sensitivity which occurred in S phase cells which are undergoing DNA synthesis . Mitotic gene conversion and mitotic crossing-over were induced by nitrous acid in cells at all stages of the cell cycle with a peak of induction of both events occurring at the time of maximum cell lethality . The lack of correlation observed between maximum cell and the maximum induction of mitotic intragenic recombination suggest that other DNA-repair mechanisms besides DNA-recombination repair are involved in the recovery of inactivated yeast cells during the cell cycle. Proc Natl Acad Sci U S A, 1978 Sep, 75(9), 4384 - 8 Rate of macromolecular synthesis through the cell cycle of the yeast Saccharomyces cerevisiae; Elliott SG et al.; Centrifugal elutriation was used to separate cells of Saccharomyces cerevisiae in balanced exponential growth according to position in the cell cycle . Macromolecular synthesis was examined . DNA synthesis was found to be periodic, but RNA and protein synthesis showed an exponential increase in rate . Two-dimensional electrophoresis was used to determine the rate of synthesis of individual proteins, with 111 of the more abundant cellular proteins selected for analysis from among the more than 1000 proteins that migrate in the system . All the examined proteins showed an exponentially increasing rate of synthesis. Genetics, 1978 Sep, 90(1), 49 - 68 Meiotic recombination and DNA synthesis in a new cell cycle mutant of Saccharomyces cerevisiae; Kassir Y et al.; Vegetative cells carrying the new temperature-sensitive mutation cdc40 arrest at the restrictive temperature with a medial nuclear division phenotype . DNA replication is observed under these conditions, but most cells remain sensitive to hydroxyurea and do not complete the ongoing cell cycle if the drug is present during release from the temperature block . It is suggested that the cdc40 lesion affects an essential function in DNA synthesis . Normal meiosis is observed at the permissive temperature in cdc40 homozygotes . At the restrictive temperature, a full round of premeiotic DNA replication is observed, but neither commitment to recombination nor later meiotic events occur . Meiotic cells that are already committed to the recombination process at the permissive temperature do not complete it if transferred to the restrictive temperature before recombination is realized . These temperature shift-up experiments demonstrate that the CDC40 function is required for the completion of recombination events, as well as for the earlier stage of recombination commitment . Temperature shift-down experiments with cdc40 homozygotes suggest that meiotic segregation depends on the final events of recombination rather than on commitment to recombination. J Gen Microbiol, 1978 Sep, 108(1), 45 - 56 Basic amino acid inhibition of cell division and macromolecular synthesis in Saccharomyces cerevisiae; Sumrada R et al.; Growth of Saccharomyces cerevisiae on poor nitrogen sources such as allantoin or proline was totally inhibited by addition of a non-degradable basic amino acid to the medium . Cells treated with lysine contained greatly reduced quantities of histidine and arginine . Conversely, lysine and histidine were severely reduced in arginase-deficient cells treated with arginine . When all three basic amino acids were present in the culture medium, growth was normal suggesting that synthesis of all three basic amino acids was decreased by an excess of any one of them . Inhibition of growth was accompanied by a fivefold increase in the observed ratio of budded to unbudded cells . These morphological changes suggested that DNA synthesis was inhibited . Consistent with this suggestion, addition of a basic amino acid to the culture medium substantially reduced the ability of the cells to incorporate {14C}uracil into alkali-resistant, trichloroacetic acid-precipitable material . RNA and protein synthesis, although decreased, were less sensitive to the effects of such additions. Genetika, 1978 Sep, 14(9), 1495 - 1502 {Regulation of purine nucleotide biosynthesis in mutant Saccharomyces cerevisiae yeasts with increased sensitivity of the pathway for de novo synthesis to inhibition by exogenous guanine}; Smolina VS et al.; Aza 165 and aza 238 Saccharomyces cerevisiae mutants characterized by a 2.5 times higher sensitivity of the de novo purine synthesis to the inhibitory effect of exogenous guanine, as compared with the wild type strain, have been selected by their sensitivity to 8-azaguanine . The exogenous guanine somewhat inhibits the growth and synthesis of nucleis acids in mutants, this being due in vivo neither to permeability changes of the cell membrane, nor to concentration changes of guanilic derivatives in the acid-soluble pool of yeast cells . Using cell-free extract of the strain aza 165, it has been shown that the synthesis of the first product of metabolic pathway for de novo formation of purines, phosphoribosylamine, is inhibited by GMP by 81% and only by 35% in the 15V-P4 strain of the wild type . The inhibition by other end products, IMP and AMP, is the same in both wild and mutant strains . The enhanced sensitivity of the purine synthesis to guanine in vivo is thus due to changes in regulatory properties of the key enzyme of purine nucleotide formation, phosphoribosylpyrophosphate amido-transferase (EC 2.4.2.14) . This change in the regulation of purine synthesis in yeast is likely to be a mechanism to compensate the genetically controlled defect in end steps of the biosynthesis pathway, i.e . the incapability of converting guanilic derivatives to adenilic ones . However, the information concerning the regulation of PRPP-amido-transferase activity responsible for differential sensitivity to adenilic and guanilic nucleotides in yeast is not lost but only strongly repressed. Biochem J, 1978 Sep 1, 173(3), 773 - 86 Rapid purification and properties of potassium-activated aldehyde dehydrogenase from Saccharomyces cerevisiae; Bostian KA et al.; A method for the purification of yeast K+-activated aldehyde dehydrogenase is presented which can be completed in substantially less time than other published procedures . The enzyme has a different N-terminal amino acid from preparations previously reported, and other small differences in amino acid content . These differences may be the result of differential proteolytic digestion rather than a different protein in vivo . A purification step involves the biospecific adsorption on affinity columns containing immobilized nucleotides in the absence of the substrate aldehyde . Direct binding studies with the coenzyme in the absence of aldehyde reveal 4 NAD sites per tetrameric molecule, each with a dissociation constant of 120 micron . These results conflict with properties of preparations previously reported and may conflict with kinetic models that have aldehyde as the leading substrate . Binding to Blue Dextran affinity columns suggests the presence of a dinucleotide fold in common with other dehydrogenases and kinases. Biochem J, 1978 Sep 1, 173(3), 787 - 98 Kinetics and reaction mechanism of potassium-activated aldehyde dehydrogenase from Saccharomyces cerevisiae; Bostian KA et al.; Data from steady-state kinetic analysis of yeast K+-activated aldehyde dehydrogenase are consistent with a ternary complex mechanism . Evidence from alternative substrate analysis and product-inhibition studies supports an ordered sequence of substrate binding in which NAD+ is the leading substrate . A preincubation requirement for NAD+ for maximum activity is also consistent with the importance of a binary enzyme-NAD+ complex . Dissociation constant for enzyme-NAD+ complex determined kinetically is in reasonable agreement with that determined by direct binding . The order of substrate addition proposed here differs from that proposed for a yeast aldehyde dehydrogenase previously reported . Different methods of purification produced an enzyme that showed similar kinetic characteristics to those reported here. Mol Gen Genet, 1978 Aug 17, 164(2), 217 - 25 An alkaline sucrose gradient analysis of the mechanism of nuclear DNA synthesis in the yeast Saccharomyces cerevisiae; Johnston LH et al.; Using alkaline sucrose gradients the mechanism of DNA synthesis has been investigated in both log-phase and synchronised cultures of the yeast Saccharomyces cerevisiae . DNA synthesis proceeds via a heterogeneous population of single-stranded intermediates between 7 and 60 x 10(6) daltons in size . The size of these molecules and a comparison of their behaviour in log-phase and synchronised cultures suggests they are nascent or completed replicons . The progressive increase in molecular weight of these intermediates during S in synchronous cultures was used as a measure of the rate of DNA synthesis per single strand . During the first half of the period of DNA synthesis in the culture, the observed rate of elongation was 0.82 x 10(6) daltons/min . Later in S, an apparent increase in rate was detected, but this may have reflected the joining of completed replicons . In our gradients the pattern of DNA synthesis in the cell cycle mutants cdc2 and 6, thought to make incomplete or faulty DNA at the restrictive temperature (Hartwell, 1974), closely resembled that of the wild-type. J Cell Biol, 1978 Aug, 78(2), 401 - 14 Nucleation of microtubules in vitro by isolated spindle pole bodies of the yeast Saccharomyces cerevisiae; Hyams JS et al.; Spindle pole bodies (SPBs) were isolated from the yeast Saccharomyces cerevisiae by an adaptation of the Kleinschmidt monolayer technique . Spheroplasts prepared from the cells were lysed on an air-water interface . Spread preparations were picked up on grids, transferred to experimental test solutions, and prepared for whole-mount electron microscopy . Using purified exogenous tubulin from porcine brain tissue, the isolated SPBs were shown to nucleate the assembly of microtubules in vitro . Microtubule growth was directional and primarily onto the intranuclear face of the SPB . Neither the morphology nor the microtubule-initiating capacity of the SPB was affected by treatment with the enzymes DNase, RNase, or phospholipase although both properties were sensitive to trypsin . Analysis of SPBs at various stages of the cell cycle showed that newly replicated SPBs had the capacity to nucleate microtubules . SPBs isolated from exponentially growing cells initiated a subset of the yeast spindle microtubules equivalent to the number of pole-to-pole microtubules seen in vivo . However, SPBs isolated from cells in stationary phase and therefore arrested in G1 nucleated a number of microtubules equal to the total chromosomal and pole-to-pole tubules in the yeast spindle . This may mean that in G1-arrested cells, the SPB is associated with microtubule attachment sites of the yeast chromatin. Mutat Res, 1978 Aug, 54(1), 23 - 5 Induction of gene conversion in Saccharomyces cerevisiae by the nitrofluran derivative furylfuramide (AF-2); Murthy MS et al.; The nitrofuran derivative furylfuramide (AF-2) is known to be both mutagenic and carcinogenic in a number of test systems . In this report we show that AF-2 can also induce gene conversion in diploid yeast in a manner dependent on both duration treatment and concentration. Mutat Res, 1978 Aug, 51(2), 165 - 80 Responses of radiation-sensitive mutants of Saccharomyces cerevisiae to lethal effects of bleomycin; Moore CW; Haploid and diploid strains of yeast containing genes conferring radiation-sensitivity were studied under growing and nongrowing experimental conditions for their relative sensitivities to growth-inhibitory effects of bleomycin (BM) . The rad1, rad2, rad3, rad4, rad5 (and allelic rev2), rad7, rad10, rad11, rad 12, rad14, rad15, rad16 and rev3 strains exhibited responses similar to normal (Rad+) yeast strains . It is concluded from these findings that the excision-repair function deficient in several of these mutant strains is not important for repair of bleomycin-induced damages in yeast . The sensitive strains contained rad6, rad9, rad18, rad22, rad50, rad51, rad52, rad53, rad54, rad55, rad56, rad57 and rs1 . Strains bearing rad8 or rad19 could not be classified unambiguously . With one exception, all rad mutants found very sensitive to BM were sensitive to X-rays, suggesting that some aspect of the repair of BM- and X-ray-induced damages in yeast may be similar . Sensitivities to BM and radiation co-segregated in pedigrees following meiosis, and several BM-resistant revertants isolated from two rad6 mutant strains sensitive to BM, X-rays and UV were cross-resistant to all three agents . These results confirm that the rad mutants were responsible for the cross-sensitivities in the original strains. Mol Gen Genet, 1978 Jul 11, 163(2), 153 - 67 S-adenosyl methionine requiring mutants in Saccharomyces cerevisiae: evidences for the existence of two methionine adenosyl transferases; Cherest H et al.; Mutants requiring S-adenosyl methionine (SAM) for growth have been selected in Saccharomyces cerevisiae . Two classes of mutants have been found . One class corresponds to the simultaneous occurrence of mutations at two unlinked loci SAM1 and SAM2 and presents a strict SAM requirement for growth on any medium . The second class corresponds to special single mutations in the gene SAM2 which lead to a residual growth on minimal medium but to normal growth on SAM supplemented medium or on a complex medium like YPGA not containing any SAM . These genetic data can be taken as an indication that Saccharomyces cerevisiae possesses two isoenzymatic methionine adenosyl transferases (MAT) . In addition, SAM1 and SAM2 loci have been identified respectively with the ETH-10 and ETH2 loci previously described . Biochemical evidences corroborate the genetic results . Two MAT activities can be dissociated in a wild type extract (MATI and MATII) by DEAE cellulose chromatography . Mutations at the SAM1 locus lead to the absence or to the modification of MATII whereas mutations at the SAM2 locus lead to the absence or to the modification of MATI . Moreover, some of our results seem to show that MATI and MATII are associated in vivo. J Biol Chem, 1978 Jul 10, 253(13), 4555 - 65 CTP-phosphatidic acid cytidyltransferase from Saccharomyces cerevisiae . Partial purification, characterization, and kinetic behavior; Belendiuk G et al.; CTP-phosphatidic acid cytidyltransferase catalyzes the formation of CDP-diglyceride from CTP and phosphatidic acid . The enzyme was solubilized from crude mitochondrial membrane by treatment with digitonin and was further purified by chromatography on DEAE-Sephadex, quaternary aminoethyl (QAE) Sephadex, and Sepharose 6B columns . At this stage the enzyme, enriched 550-fold over crude cell homogenate, still remains associated with phospholipid and has an estimated approximate molecular weight of 400,000 on the basis of gel filtration chromatography . Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the 550-fold enriched enzyme yielded two major protein bands having molecular weights of 45,000 and 19,000 . The enzyme exhibits an absolute dependence on Triton X-100, a sharp Mg2+ dependence with an optimum at 20 mM, and a pH optimum of 6.5 for activity . The product of the CTP-phosphatidic acid cytidyl-transferase reaction has been isolated and identified as CDP-diglyceride, both for the crude enzyme preparation as well as for the 550-fold enriched enzyme . CTP-phosphatidic acid cytidyltransferase is capable of catalyzing the reverse reaction in the presence of pyrophosphate, utilizing CDP-diglyceride as substrate . The product of the reverse reaction was identified as CTP . Kinetic analysis of the behavior of CTP-phosphatidic acid cytidyltransferase was performed at three different stages of its purification . Initial analysis of the data yielded biphasic behavior in double reciprocal plots with respect to both substrates . Hill plots of the data indicated the presence of negative cooperativity . A detailed analysis of the kinetic behavior was performed on the enzyme purified 550-fold . The data suggest a mechanism involving two distinct cycles of catalysis, responsive to homotropic modification, with different affinities for both substrates . Further analysis of the kinetic behavior in the presence of inhibitors (dCTP and PPi) yielded a reaction order for the entrance of substrates and departure of products from the reaction cycles . The high affinity site catalyzes the reaction via a double displacement mechanism and is the predominant form at low concentrations of substrates . At high concentrations of substrates the low affinity site starts contributing significantly to the reaction velocity with an ordered single displacement mechanism . In each case CTP is the first substrate to attach and PPi is the first product released. Biochim Biophys Acta, 1978 Jul 7, 525(1), 87 - 92 Characterization of sterol-ester hydrolase in Saccharomyces cerevisiae; Taketani S et al.; A homgenate of Saccharomyces cerevisiae grown under semi-anaerobic as well as aerobic conditions was found to catalyze the hydrolysis of fatty acid esters of sterols in the presence of Triton X-100 . The enzyme levels in cells grown under various conditions were similar and the enzyme had a broad substrate specificity for sterol esters . The enzyme was localized in the mitochondrial fraction for the aerobically grown cells and in the mitochondrial and cytosolic fractions for the semi-anaerobically grown cells. Mikrobiologiia, 1978 Jul-Aug, 47(4), 711 - 6 {Comparative study of the physiological and biochemical characteristics of the varying ploidy of Saccharomyces cerevisiae strains in the process of their growth}; Shkidchenko AN et al.; The growth of Saccharomyces cerevisiae strains having different ploidy was compared in the conditions of periodic cultivation, and was found to consist of two stages: (1) at the account of glucose utilization and (2) due to assimilation of cellular metabolites following a period of adaptation . The secondary growth was linear . The haploid, diploid and triploid strains differed in the character of growth, substrate utilization, the rate of respiration and the economic coefficient . Their qualitative protein composition was the same though certain changes were detected in the content of individual amino acids . The amount of essential amino acids (their sum) in proteins increased when the yeast started to oxidize cellular metabolites instead of glucose utilization. Mol Biol (Mosk), 1978 Jul-Aug, 12(4), 863 - 7 {Electrophoretic study of the acid soluble proteins of Saccharomyces cerevisiae yeast chromatin}; Suchilene SP et al.; Fractionation of acid-soluble proteins from yeast Saccharomyces cerevisiae chromatin by gel electrophoresis suggested the existence of four histonestone fractions--H2a, H2b, H3, H4 and histone H1-like protein . The latter was isolated according to the second method of Johns and extracted with 5% HClO4 . Amino acid analysis of the histone H1-like protein showed a moderately high content of basic amino acids, but a much lower ratio of lysine: arginine (approximately 3) than that of the hisone H1 from higher eukaryotes . In addition to histone H1-like protein a protein X was also extracted with 5% HC1O4 . The sequence of the electrophoretic mobilities of histone fractions from yeast coincides with those of histone fractions from plants--H4 greater than H3 greater than H2a greater than H2b greater than H1. Arch Microbiol, 1978 Jun 26, 117(3), 239 - 45 Plasma-membrane lipid composition and ethanol tolerance in Saccharomyces cerevisiae; Thomas DS et al.; Populations of cells suspended anaerobically in buffered (pH 4.5) M ethanol remained viable to a greater extent when their plasma membranes were enriched in linoleyl rather than oleyl residues irrespective of the nature of the sterol enrichment . However, populations with membranes enriched in ergosterol or stigmasterol and linoleyl residues were more resistant to ethanol than populations enriched in campesterol or cholesterol and linoleyl residues . Populations enriched in ergosterol and cetoleic acid lost viability at about the same rate as those enriched in oleyl residues, while populations grown in the presence of this sterol and palmitoleic acid were more resistant to ethanol . Suspending cells in buffered ethanol for up to 24 h did not lower the ethanol concentration. J Biol Chem, 1978 Jun 25, 253(12), 4402 - 7 Identification of enzymically inactive apocytochrome c peroxidase in anaerobically grown Saccharomyces cerevisiae; Djavadi-Ohaniance L et al.; Anaerobically grown yeast cells lack cytochrome c peroxidase activity but rapidly acquire it upon aeration . In order to study the oxygen-induced formation of this hemoprotein, extracts of anaerobic and aerobic yeast cells were resolved by one- and two-dimensional acrylamide gel electrophoresis and the separated polypeptides were then checked for comigration with radiolabeled purified cytochrome c peroxidase from aerobic cells or for reaction with cytochrome c peroxidase antiserum . Both types of extracts contained roughly equal amounts of a polypeptide which was indistinguishable from apocytochrome c peroxidase with respect to antigenicity, isoelectric point, and apparent molecular weight in three different gel systems . In confirmation of an earlier report by Sels . A.A., and Cocriamont, C . (1968) (Biochem . Biophus . Res . Commun . 32, 192-198) the oxygen-induced formation of cytochrome c peroxidase was insensitive to inhibitors of protein synthesis and could be mimicked by the addition of heme to extracts of anaerobic cells . We conclude that the oxygen-induced formation of yeast cytochrome c peroxidase involves the addition of heme to the apoenzyme which is already present in the anaerobically grown cells. Biochim Biophys Acta, 1978 Jun 23, 529(3), 429 - 37 Azasterol inhibitors in yeast . Inhibition of the 24-methylene sterol delta24(28)-reductase and delta24-sterol methyltransferase of Saccharomyces cerevisiae by 23-azacholesterol; Pierce HD Jr et al.; The effects of 23-azacholesterol on sterol biosynthesis and growth of Saccharomyces cervisiae were examined . In the presence of 0.2, 0.5, and 1 micron 23-azacholesterol, aerobically-growing yeast produced a nearly constant amount of ergosta-5,7,22,24(28)-tetraenol (approx . 36% of total sterol) and slowly accumulated zymosterol with a concommitant decline in ergosterol synthesis . Growth and total sterol content of yeast cultures treated with 0.2-1 micron 23-azacholesterol were similar to that of the control culture . Yeast cultures treated with 5 and 10 micron 23-azacholesterol produced mostly zymosterol (58-61% of total sterol), while ergosta-5,7,22,24(28)-tetraenol production declined to less than 10% of total sterol . The observed changes in the distribution of sterols in treated cultures are consistent with inhibition of 24-methylene sterol 24(28)-sterol reductase (total inhibition at 1 micron 23-azacholesterol) and of 24-sterol methyltransferase (71% inhibition at 10 micron 23-azacholesterol) . Yeast cultures treated with 10 micron 23-azacholesterol were found to contain 4,4-dimethylcholesta-8,14,24-trienol and 4alpha-methylcholesta-8,14,24-trienol, which were isolated and characterized for the first time. Mol Biol Rep, 1978 Jun 16, 4(2), 83 - 6 Altered mitochondrial ribosomes in a cold-sensitive mutant of Saccharomyces cerevisiae; Spithill TW et al.; A mutation at a new locus denoted tsr1 which lies very close to the ery1 locus and 21S rRNA gene in mitochondrial DNA of Saccharomyces cerevisiae, confers conditional respiratory deficiency on cells grown at low temperature, namely 18 degrees . Studies on mitochondria isolated from a strain carrying the mutatated tsr1 locus demonstrate that the rate of mitochondrial protein synthesis is cold-senitive at 18 degrees . The large subunit of the mitochondrial ribosomes isolated from the mutant strain is unstable during extraction and the isolated ribosomes are shown to be defective in catalyzing the poly U-directed synthesis of polyphenylalanine . It is concluded that the tsr1 locus is involved in the determination of the properties of the large subunit of the mitochondrial ribosome. Mol Biol Rep, 1978 Jun 16, 4(2), 101 - 4 Circular mitochondrial DNA molecules from petite mutants of Saccharomyces cerevisiae: resolution by polyacrylamide gel electrophoresis; Shepherd MH et al.; Mitochondrial DNA (mtDNA) from petite strain K45 of Saccharomyces cerevisiae contains about 7% circular DNA molecules which comprise a simple oligomeric series based on a monomeric size of 1.7 kilobase pairs . Electrophoresis of K45 mtDNA on a polyacrylamide-agarose slab gel fractionates the mtDNA into a major band (containing linear DNA) and several faster running minor bands each containing particular size class of circular DNA molecules . From study of mtDNA from K45 and two other simple petites it was found that the mobility of circles is inversely proportional to the logarithm of the circle size . Polyacrylamide gel electrophoresis thus permits the separation of circular mtDNA from the linear mtDNA of simple petites, and physically resolves circles of different size from one another. Mol Gen Genet, 1978 Jun 14, 162(2), 191 - 201 Preferential deletion of a specific region of mitochondrial DNA in Saccharomyces cerevisiae by ethidium bromide and 3-carbethoxy-psoralen: directional retention of DNA sequence; Fukuhara H et al.; Grande strains of Saccharomyces cerevisiae were mutagenized either by ethidium bromide or by 3-carbethoxy-psoralen (a monofunctional furocoumarin derivative) activated by 365nm light . 973 primary rho- clones induced were randomly collected and analyzed individually for the presence or absence of fifteen mitochondrial genetic markers . 1 . Under mild conditions of mutagenesis, 83% of the primary clones showed single-deletion genotypes; a unique order of 14 markers could be deduced from the patterns of the deletion . The gene order confirmed our previous map constructed from the analysis of established non-random petite clones . From the frequencies of disjunction between markers, the distance separating 14 mitochondrial markers were estimated . 2 . One region, carrying oxi-3, pho-1 and mit 175 loci, was preferentially lost in rho- mutants: there is a strong constraint in the frequencies of various genotypes found in rho- clones . On each side of this particular region, a bidirectionally oriented pattern of retention of markers is observed. J Biol Chem, 1978 Jun 10, 253(11), 3792 - 7 Assembly of the mitochondrial membrane system . Genetic complementation of mit- mutations in mitochondrial DNA of Saccharomyces cerevisiae; Foury F et al.; A method has been devised to test intergenic complementation of mutations in the mitochondrial DNA of Saccharomyces cerevisiae . The test is based on the observation that diploids issued from pairwise crosses of certain mit- mutants with deficiencies in cytochrome oxidase, or coenzyme QH2-cytochrome c reductase, acquire high levels of respiratory activity shortly after zygote formation . Under our experimental conditions neither biochemical complementation, interallelic complementation, nor recombination has been found to contribute to any significant extent toward the respiration measured in the diploids at early times . The test has been used to study the number of complementation groups represented by a large number of mit- mutants . Results of pairwise crosses of mutants in the oxi 1, oxi 2, oxi 3, cob 1, and cob 2 loci indicate that complementation occurs between the oxi and cob loci between different oxi loci but not between the two cob loci . The five loci have, therefore, been assigned to four different complementation groups. Mol Gen Genet, 1978 Jun 1, 162(1), 23 - 34 Mapping of regions on cloned Saccharomyces cerevisiae 2-mum DNA coding for polypeptides synthesized in Escherichia coli minicells; Hollenberg CP; Saccharomyces cerevisiae 2-mum DNA and some of its restriction fragments were integrated in vector pCR1 ,pBR313 or pBR322 and their expression in Escherichia coli P678-54 minicells was analyzed . 2mum DNA inserted at the EcoRI site of pCR1 or pBR313 and at the PstI site of pBR322 promoted the synthesis of polypeptides of 48,000, 37,000, 35,000 and 19,000 daltons . The DNA regions coding for these polypeptides were mapped on the 2-mum DNA molecule by insertion of single EcoRI or HindIII restriction fragments and comparison of the polypeptides produced . For the synthesis of the 37,000 dalton polypeptide, intact sites RIB and H3 were required . The disappearance of the 37,000 dalton polypeptide on interruption of one of these sites by insertion of the vector, was correlated with the appearance of a polypeptide of 22,000 or 23,500 daltons respectively . The DNA sequence coding for the 37,000 daltons polypeptide, therefore, has to be located in the S-loop region close to or overlapping with the site RIB and H3 . Assuming that the 22,000 and the 23,500 dalton polypeptides are truncated forms of the 37,000 dalton polypeptide, the last polypeptide can be exactly mapped . The polypeptide of 48,000 daltons was mapped to that half of the L-loop segment containing the sites H1 and H2 . If, however, HindIII fragment H1-H2 was expressed, the 48,000 dalton polypeptide was lost and concomitantly a 43,000 dalton polypeptide appeared . We assume that this polypeptide results from early termination of the polypeptide of 48,000 daltons . The 35,000 and 9,000 dalton polypeptides were mapped to the S-loop region . The integrated inverted repeat sequence of yeast 2-mum Dna did not induce any detectable insert-specific polypeptide synthesis. J Cell Sci, 1978 Jun, 31, 71 - 8 Effects of temperature and nutritional conditions on the mitotic cell cycle of Saccharomyces cerevisiae; Jagadish MN et al.; Yeast cells were cultivated at different growth rates in a chemostat by alterations in the flow of the limiting nutrient glucose and in batch cultures where variations in growth rate were achieved by alterations in the composition of nutrients . It was observed that the stage in the cycle at which S-phase was completed varied with growth rate . The faster the growth rate, the earlier the stage in the cycle in which completion of S-phase occurred . When stage in the cycle is converted into time before division it was observed that the time from completion of S-phase to cell division varied only slightly with growth rate except at extremely slow growth rates . Expansion of cell cycle transit time as the growth rate was slowed was achieved primarily by an expansion in time of the period from division to the completion of S-phase . In contrast, when cells were grown at different rates by alterations in the temperature of cultivation, completion of S-phase occurred at approximately the same stage in the cell cycle at all growth rates. Can J Microbiol, 1978 Jun, 24(6), 637 - 42 Evolution of ethylene by Saccharomyces cerevisiae as influenced by the carbon source for growth and the presence of air; Thomas KC et al.; Effects of the carbon source and oxygen on ethylene production by the yeast Saccharomyces cerevisiae have been studied . The amounts of ethylene evolved by the yeast culture were less than those detected in the blank (an equal volume of uninoculated medium), suggesting a net absorption of ethylene by the yeast cells . Addition of glucose to the lactate-grown yeast culture induced ethylene production . This glucose-induced stimulation of ethylene production was inhibited to a great extent by cycloheximide . Results suggested that the yeast cells in the presence of glucose synthesized an ethylene precursor and passed it into the medium . The conversion of this precursor to ethylene might be stimulated by oxygen . The fact that ethylene was produced by the yeast growing anaerobically and also by respiration-deficient mutants isolated from the wild-type yeast suggested that mitochondrial ATP synthesis was not an absolute requirement for ethylene biogenesis. Experientia, 1978 May 15, 34(5), 569 - 70 Carboxypeptidase Y from Saccharomyces cerevisiae: circular dichroism and fluorescence studies; Deconinck M et al.; Carboxypeptidase Y was isolated from Saccharomyces cerevisiae and its molecular structure investigated . The enzyme in the native state possesses 40% of its amino acid residues in a beta-conformation . Its tryptophan residues seem to be largely buried in an apolar and unsymmetrical environment. Biochim Biophys Acta, 1978 May 11, 524(1), 121 - 30 alpha-D-Mannosidase of Saccharomyces cerevisiae . Characterization and modulation of activity; Opheim DJ; A unique and interesting alpha-D-mannosidase (alpha-D-mannoside mannohydrolase EC 3.2.1.24) activity has been isolated from Saccharomyces cerevisiae . The enzyme was localized in a crude particulate fraction of the cell extract and was not solubilized by treatment with detergents or high ionic strength NaCl . The enzyme had a pH optimum of 6.3, Km 50 micron with p-nitrophenyl-alpha-D-mannopyranoside, and was competitively inhibited by D-mannose (Ki 20 mM) . The enzyme is not affected by ethylenediaminetetraacetic acid, a number of different cations, or sulfhydryl reagents . It was inhibited by p-chloromercuriphenyl sulfonic acid and this inhibition is prevented by the addition of substrate . The cellular concentration of alpha-D-mannosidase is inversely proportional to growth rate, suggesting that the enzyme is under catabolite repression . The level of enzyme was found to increase approx . 8-fold during sporulation . This is apparently due to de novo synthesis, since inhibition of protein synthesis by cycloheximide prevents the increase in enzyme activity. Mol Gen Genet, 1978 May 3, 161(2), 221 - 3 Ribosomal RNA transcription in a mutant of Saccharomyces cerevisiae defective in ribosomal protein synthesis; Shulman RW et al.; In Saccharomyces cerevisiae, the transcription of ribosomal precursor RNA is severely inhibited in the absence of protein synthesis . However, such transcription is not dependent on the synthesis of ribosomal proteins, nor on the synthesis of mRNA for ribosomal proteins, nor on the processing of ribosomal precursor RNA. Mol Gen Genet, 1978 May 3, 161(2), 153 - 73 On the formation of rho - petites in yeast . III . Effects of temperature on transmission and recombination of mitochondrial markers and on rho - cell formation in temperature sensitive mutants of Saccharomyces cerevisiae; Backhaus B et al.; The rho-factor stability is shown to be affected by four conditional mutations, tsm-8 (mitochondrial), tsp-20, tsp-25 and tsp-30 (nuclear) . Growth of mutant cells at high temperature (35 degrees C) results in the rapid production of rho - cells and concomittantly in the decrease of the ability to transmit mitochondrial genetic information to the rho + progeny of crosses . Kinetics of rho - cell formation during growth at 35 degrees C have been compared with variations in transmission and recombination of mitochondrial markers in crosses . In all cases the transmission of mitochondrial markers of the ts-parent decreases as the number of cell generations increases . The frequencies of recombinants between mitochondrial markers either increase or decrease depending on the markers considered and the alleles of the omega-locus involved in the crosses . The results of all crosses performed have been compared with the predictions of the model for recombination and segregation of mitochondrial genes proposed by Dujon et al . (1974) . This comparison indicates that the main result of high temperature treatment is a diminution of the input of mitochondrial information from the ts-parent into zygotes . Consequences of the induced variations of input follow the predictions of the model . The correlation found in ts-strains between the reduction of input in crosses and the formation of rho - cells is discussed in terms of molecular events occurring in mitDNA molecules during high temperature induction of rho + to rho - mutation. Mutat Res, 1978 May, 57(2), 155 - 61 Mutagenicity of methylated N-nitrosopiperidines in Saccharomyces cerevisiae; Larimer FW et al.; N-Nitrosopiperidine (NP) and a number of methylated derivatives were examined for mutagenicity in Saccharomyces cerevisiae . NP, 2-methyl-NP, 3-methyl-NP, 4-methyl-NP and 3,5-dimethyl-NP were mutagens when metabolic activation (rat-liver microsomes) was provided . 2,6-Dimethyl-NP was not a mutagen . The NPs giving a positive response stimulated forward mutation to canavanine resistance (CAN1 leads to can1) and reversion of the his1-7 missense marker . Neither locus revertants nor suppressors of the lys1-1 ochre marker were induced, nor were revertants of the putative frameshift hom3-10. J Bacteriol, 1978 May, 134(2), 629 - 35 Stable denaturation of chromosomal DNA from Saccharomyces cerevisiae during meiosis; Klein HL et al.; Partial denaturation of Saccharomyces cerevisiae chromosomal DNA was found to occur spontaneously during meiosis . Short regions of strand separation (300 base pairs long) were seen in DNA molecules prepared for electron microscopy by the aqueous spreading technique . These regions were clustered along the DNA . The time course of their appearance indicated that the denatured regions were present during the periods of premeiotic DNA replication and recombination . A similar pattern of denaturation was also detected in the DNA from vegetatively grown cells of a conditional cdc8 mutant, which is defective in DNA replication. Mutat Res, 1978 May, 50(2), 195 - 206 Dose-rate effects of 8-methoxypsoralen plus 365-NM irradiation on cell killing in Saccharomyces cerevisiae; Averbeck D et al.; Tow types of dose-rate effect that alter the survival response of haploid yeast cells to 8-methoxypsoralen (8-MOP) plus treatment with irradiation at 365 nm were studied . (1) When the concentration of 8-MOP was varied between 9.2 X 10(-5) and 2.3 X 10(-8) M and the dose rate of 365-nm irradiation kept constant, the efficiency of the irradiation for killing increased relatively to that of 8-MOP whe the concentration of 8-MOP decreased . This indicated that there was no strict reciprocity between radiation dose and concentration of drug . (2) When the dose rate of radiation was varied between 0.66 X 10(3) and 108 X 10(3) J m-2 h-1 and the concentration of 8-MOP was kept constant, the survival of wild-type cells increased strikingly at low dose rates of radiation as compared with high dose rates . Cells responded more to changes at low dose rates than to equal changes a high dose rates . The high resistance of wild-type cells to 8-MOP plus radiation delivered at low dose rates absent from rad 1-3 cells defective in excision-repair . This suggests that the dose-rate effect seen in wild-type cells depended at least in part on an active excision-repair function . At low dose rates of radiation, the shoulder of the survival curve for rad1-3 cells, i.e . the ability to accumulate sub-lethal damage, was increased by a factor of about 2 when compared with that seen at a high dose rate . Thus it is likely that at low dose rates a repair function other than excision-resynthesis may operate in rad1-3 cells. J Bacteriol, 1978 May, 134(2), 446 - 57 Genetic control of galactokinase synthesis in Saccharomyces cerevisiae: evidence for constitutive expression of the positive regulatory gene gal4; Matsumoto K et al.; Temperature-sensitive (ts) mutants for the gal80 and gal4 genes of Saccharomyces cerevisiae were isolated and characterized . These mutants were classified into two categories; one showed thermolability (TL) and the other showed temperature-sensitive synthesis (TSS) of the respective products . Both the TL and TSS gal80 mutants are constitutive for galactokinase activity at 35 degrees C and, because they are derived from a dominant super-repressible GAL80s mutant, are uninducible at 25 degrees C . Both the TL and TSS gal4 mutants are galactose negative at 35 degrees C and galactose positive at 25 degrees C . None of the ts gal4 mutations affected the thermolability of galactokinase activity in cell extracts . Induction of galactokinase activity was studied with these mutants . The results indicate that the gal80 gene codes for a repressor and the gal4 gene codes for a positive factor indispensable for the expression of the structural genes or their products . However, striking evidence that the expression of the gal4 gene is constitutive and not under the control of gal80 was provided by a kinetic study with the TL gal4 mutant . The TL gal4 mutant pregrown in glycerol nutrient medium at 35 degrees C showed a prolonged lag period (35 min) in the induction of galactokinase activity at 25 degrees C, whereas the same mutant pregrown at 25 degrees C showed the same lag period as those observed in the wild-type strain and a revertant clone derived from the TL gal4 mutant (15 min). J Gen Microbiol, 1978 May, 106(1), 145 - 51 Purification and properties of the arginine-specific carbamoyl-phosphate synthase from Saccharomyces cerevisiae; Price CW et al.; The arginine-specific carbamoyl-phosphate synthase of yeast was stabilized sufficiently to allow partial purification of the enzyme (30- to 40-fold) . The synthase (mol . wt 115000) comprised two unequal subunits: a heavy subunit (mol . wt 80000) capable of catalysing synthesis of carbamoyl phosphate with ammonia as a nitrogen donor and a light subunit conferring upon the holoenzyme the ability to utilize glutamine . The enzyme had unusually high affinity for ATP (Km = 0.2 mM) and atypical negative cooperativity for glutamine binding ({S}0.5 = 0.25 mM) . Glutamine activity was not modulated by possible effectors such as arginine, ornithine or N-acetylglutamate . Thus, although the yeast arginine enzyme physically and functionally resembles the single enteric synthase, the systems differ substantially both in kinetic properties and in regulation of activity. Arch Microbiol, 1978 Apr 27, 117(1), 73 - 7 Electron microscopy of germinating ascospores of Saccharomyces cerevisiae; Kreger-Van Rij NJ; The wall of mature ascospores of Saccharomyces cerevisiae showed in sections under the electron microscope a dark outer layer and a lighter inner layer . The latter was composed of a greyish inner part and a light outer part . During germination, the spore grew out at one side and the dark outer layer was broken . Of the light inner layer, the inner greyish part became the wall of the vegetative cell, but the extended part of the cell had a new wall. Mol Gen Genet, 1978 Apr 6, 160(2), 231 - 4 A correlation between shortened life span and UV-sensitivity in some strains of Saccharomyces cerevisiae; Muller I et al.; From a UV-irradiated sample of diploid cells several clones were isolated, which produced cells with a shortened life span . A closer examination of three of these clones showed among other deviations from the wild type a higher sensitivity to UV-irradiation . Three other clones, which were selected from a haploid strains as UV-sensitive mutants, proved to be shortlived as well . In all these strains photoreactivation and liquid holding reactivation were unimpaired . There was no cross-sensitivity to X-irradiation . The correlation between shortened life span and UV-sensitivity is discussed. J Cell Sci, 1978 Apr, 30, 331 - 52 The role of spindle pole bodies and modified microtubule ends in the initiation of microtubule assembly in Saccharomyces cerevisiae; Byers B et al.; The spindle poles of the budding yeast, Saccharomyces cerevisiae, have been removed from mitotic and meiotic cells by osmotic lysis of spheroplasts . The spindle pole bodies (SPBs)--diskoidal structures also termed 'spindle plaques'--have been analysed for their ability to potentiate the polymerization of microtubules in vitro . Free SPBs were completely deprived of any detectable native microtubules by incubation in the absence of added tubulin and were then challenged with chick neurotubulin, which had been rendered partially defective in self-initiation of repolymerization . Electron microscopy revealed that these SPBs served as foci for the initiation of microtubule polymerization in vitro . Because the attached microtubules elongated linearly with time but did not increase in numbers after the first stage of the reaction, it is apparent that there are a limited number of sites for initiation . The initiating potential of the SPBs was found to be inhibited by enzymic hydrolysis of protein but not of DNA . The microtubule end proximal to the site of initiation on the SPB is distinguished by a 'closed' appearance because of a terminal component which is continuous with the microtubule wall, whereas the distal end has the 'open' appearance characteristic of freely repolymerized neurotubules . SPBs which were partially purified on sucrose gradients retained their ability to initiate the assembly of microtubules with the same structural differentiation of their ends . The occurrence of closed proximal ends on native yeast microtubules suggests that closed ends may play a role in the initiation of microtubule polymerization in vivo, as well as in vitro. J Bacteriol, 1978 Apr, 134(1), 48 - 59 Tryptophan biosynthesis in Saccharomyces cerevisiae: control of the flux through the pathway; Miozzari G et al.; Enzyme derepression and feedback inhibition of the first enzyme are the regulatory mechanisms demonstrated for the tryptophan pathway in Saccharomyces cerevisiae . The relative contributions of the two mechanisms to the control of the flux through the pathway in vivo were analyzed by (i) measuring feedback inhibition of anthranilate synthase in vivo, (ii) determining the effect of regulatory mutations on the level of the tryptophan pool and the flux through the pathway, and (iii) varying the gene dose of individual enzymes of the pathway at the tetraploid level . We conclude that the flux through the pathway is adjusted to the rate of protein synthesis by means of feedback inhibition of the first enzyme by the end product, tryptophan . The synthesis of the tryptophan enzymes could not be repressed below a basal level by tryptophan supplementation of the media . The enzymes are present in excess . Increasing or lowering the concentration of individual enzymes had no noticeable influencing on the overall flux to tryptophan . The uninhibited capacity of the pathway could be observed both upon relieving feedback inhibition by tryptophan limitation and in feedback-insensitive mutants . It exceeded the rate of consumption of the amino acid on minimal medium by a factor of three . Tryptophan limitation caused derepression of four of the five tryptophan enzymes and, as a consequence, led to a further increase in the capacity of the pathway . However, because of the large reserve capacity of the "repressed" pathway, tryptophan limitation could not be imposed on wild-type cells without resorting to the use of analogs . Our results, therefore, suggest that derepression does not serve as an instrument for the specific regulation of the flux through the tryptophan pathway. J Bacteriol, 1978 Apr, 134(1), 306 - 9 Location of the 5.8S rRNA gene of Saccharomyces cerevisiae; Skryabin KG et al.; Direct DNA sequence analysis of Saccharomyces cerevisiae ribosomal DNA cloned in an Escherichia coli plasmid revealed part of the structural gene for 5.8S rRNA at one end of a 700-base-pair EcoRI fragment . Taken with the previously established EcoRI restriction map of the ribosomal repeat unit, this sequence establishes that the yeast 5.8S RNA segment is located between the 18S and 28S segments in the 42S rRNA precursor and in the DNA which codes for it. J Bacteriol, 1978 Apr, 134(1), 237 - 45 Ribosomal DNA magnification in Saccharomyces cerevisiae; Kaback DB et al.; Strains monosomic for chromosome I of Saccharomyces cerevisiae contain 25 to 35% fewer rRNA genes than do normal diploid strains . When these strains are repeatedly subcultured, colonies are isolated that have magnified their number of rRNA genes to the diploid amount while remaining monosomic for chromosome I . We have determined the amount of DNA complementary to rRNA in viable haploid spores derived from a magnified monosomic strain . Some of these haploids contained 24 to 48% more rRNA genes than a normal euploid strain . These extra genes may be responsible for the increased number of rRNA genes in the strain monosomic for chromosome I . Genetic analysis of the haploids containing extra rRNA genes suggested that these genes are linked to chromosomal DNA and are heterozygous . They were not closely linked to any centromere and were not located on chromosome I . Furthermore, all the DNA complementary to rRNA in one of these haploid strains with magnified rRNA genes sedimented at a chromosomal molecular weight, consistent with chromosomal linkage . In addition, several new mutations mapping on chromosome I were used to show that ribosomal DNA magnification was not due to a chromosome I duplication. J Bacteriol, 1978 Apr, 134(1), 214 - 20 Polyamine auxotrophs of Saccharomyces cerevisiae; Whitney PA et al.; Strains of yeast have been constructed that are unable to synthesize ornithine and are thereby deficient in polyamine biosynthesis . These strains were used to develop a protocol for isolation of mutants blocked directly in polyamine synthesis . There were seven mutants isolated that lack ornithine decarboxylase activity; these strains exhibited greatly decreased pool levels of putrescine, spermidine, and spermine when grown in the absence of polyamines . Three of the mutants lack S-adenosylmethionine decarboxylase activity; polyamine limitation of a representative mutant resulted in an accumulation of putrescine and a decrease in spermidine and spermine . When the mutants were cultured in the absence of polyamines, a continuously declining growth rate was observed. J Bacteriol, 1978 Apr, 134(1), 208 - 13 Isolation and characterization of Saccharomyces cerevisiae mutants deficient in S-adenosylmethionine decarboxylase, spermidine, and spermine; Cohn MS et al.; Four mutants were isolated from Saccharomyces cerevisiae that are deficient in S-adenosylmethionine decarboxylase (spe2) . All four mutants are chromosomal and fall into a single complementation group tightly linked to arg1 . Since one of the mutants contained a temperature-sensitive activity, this complementation group defines the structural gene . Mutants totally lacking enzymic activity did not contain spermidine or spermine and had a greatly increased doubling time when grown in the absence of these two polyamines . Addition of 10(-6) M spermidine or 10(-5) M spermine, but not putrescine or cadaverine, restored the doubling time to that of the wild type . Diploids formed from a cross of two mutants completely deficient in spermidine and spermine were unable to sporulate in the absence of added spermidine or spermine . We obtained evidence that arg1 was not located on any of the 17 known chromosomes, and therefore we postulate that arg1 and spe2 are located on a new 18th chromosome. J Bacteriol, 1978 Apr, 134(1), 200 - 7 L-Asparagine auxotrophs of Saccharomyces cerevisiae: genetic and phenotypic characterization; Jones GE; L-Asparagine auxotrophy in Saccharomyces cerevisiae is the result of mutation in each of two unlinked cistrons, ASN1 and ASN2 . Mutation in only one of these cistrons yields growth indistinguishable from that of wild-type cells under a variety of nutritional stresses . Relatively high concentrations of L-asparagine are required to permit maximal growth of the auxotrophs, and the amino acid requirement cannot be satisfied by a variety of other amino acids that serve as nitrogen sources for cell growth . Although reversion of the mutations can occur, haploid populations of cells containing only low frequencies of prototrophs can be maintained easily . In diploid cells heteroallelic for certain combinations of alleles of the two genes, mitotic recombination gives rise to prototrophic cells that accumulate to high frequency in populations of the cells. Biochim Biophys Acta, 1978 Mar 30, 528(3), 416 - 23 Quantitative aspects of free and esterified sterols in Saccharomyces cerevisiae under various conditions; Taketani S et al.; For extraction of free and esterified sterols from yeast cells, a method was devised in which both forms of sterols were extracted with light petroleum after the treatment of the cells with acetone, and then with dimethylsulfoxide . The content of sterol esters in the cells under aerobic conditions markedly increased with time, amounting to 95% of the total sterols under some conditions . However, the formed sterol esters were decreased, accompanied with an increase of free sterols, when the cells were put under anaerobic conditions . Variations of radioactivities of both sterols which had been labeled in the side chain by incubation of the cells with {Me{-14C}methionine were examined on the cells grown under various conditions . No variation was observed on the cells under aerobic conditions . On the other hand, the labeled esters were hydrolyzed to yield free sterols in the cells under anaerobic conditions . In the cells under aerobic conditions, the free sterols were found to consist mainly of ergosterol, whereas the esterified sterols contained considerable amounts of zymosterol, lanosterol, and other intermediate sterols besides ergosterol. Biochim Biophys Acta, 1978 Mar 21, 508(1), 39 - 54 The plasma membrane of Saccharomyces cerevisiae . Isolation and some properties; Santos E et al.; The isolation of Saccharomyces cerevisiae plasma membrane was carried out after hypotonic lysis of yeast protoplasts treated with concanavalin A by two independent methods: a, at low speed centrifugation and b, at high speed centrifugation in a density gradient . Several techniques (electron microscopic, enzymic, tagging, etc.) were used to ascertain the degree of purification of the plasma membranes obtained . The low speed centrifugation technique as compared with the other method gave a higher yield of plasma membranes with a similar degree of purification . Analysis of the yeast plasma membrane of normally growing cells by sodium dodecyl sulphate polyacrylamide gel electrophoresis showed at least 25 polypeptide bands . Twelve glycoprotein bands were also found, and their apparent molecular weights were determined . Treatment of the protoplasts with cycloheximide resulted in a significant decrease in the carbohydrate and protein content of the plasma membrane . The electrophoretic pattern of the plasma membrane of cycloheximide-treated cells showed a redistribution of the relative amounts of each protein band and a drastic reduction in the number of Schiff-positive bands . The isoelectric point of the most abundant proteins was low (pI 4) or lower than expected from previous data . A large part of the mannosyl transferase activity found in the cell (80%) was associated with the internal membranes, the remaining activity (20%) was located in the plasma membrane preparation . Part of the mannosyl transferase activity of the cells is located at the plasma membrane surface . Invertase (an external mannoprotein) is found in both the plasma and internal membranes, and as the specific activity dropped significantly following cycloheximide treatment of the cells, it is suggested that these membranes systems are the structures for the glycosylation of a precursor invertase and its subsequent release into the periplasmic space . Other transferase found in the plasma membrane preparation transfers glucose residues from UDPglucose to a poly(alpha(1 leads to 4) polymer identified as glycogen. Biochem J, 1978 Mar 15, 170(3), 569 - 76 The lability of the products of mitochondrial protein synthesis in Saccharomyces cerevisiae . A novel method for protein half-life determination; Bakalkin GY et al.; A method for the determination of the half-life of mitochondrial translation products in yeast in vivo is proposed . The method uses inhibitors of cytoplasmic and mitochondrial protein synthesis and is based on double-labelling pulse-chase techniques, the second label being used to estimate 'post-incorporation' during the 'chase' . For the first time the difference between post-incroporation and the widely known recycling of the label is considered . These studies show that, in the turnover of mitochondrial translation products, the problem is of post-incorporation into mitochondria (especially from the cell sap) is predominant . The results obtained with this procedure indicate that the half-life of the products of mitochondrial protein synthesis in yeast at the late-exponential phase is about 60 min . The results suggest that mitochondrial transplantation products are subject to proteolysis to acid-soluble forms. Can J Microbiol, 1978 Mar, 24(3), 228 - 37 Chromosomal mutants of Saccharomyces cerevisiae affecting the cell wall binding site for killer factor; Al-Aidroos K et al.; Fifty-two killer, factor-resistant, nuclear mutants were isolated from sensitive strains of yeast and assorted into three functional groups . All but one mutant owed their resistance to an alteration in the cell wall binding site for killer . In several mutant strains, an alteration at the site of killer binding was associated with a change in the susceptibility of the cell wall to degradation by glusulase . The killer-binding site could be inactivated by periodate but not by pronase treatment . The nature of the site is discussed. Arch Microbiol, 1978 Mar, 116(3), 275 - 8 Localization of polyphosphate in vacuoles of Saccharomyces cerevisiae; Urech K et al.; Virtually all of the polyphosphate (PP) present in yeast protoplasts can be recovered in a crude particulate fraction if polybase-induced lysis is used for disrupting the protoplasts . This fraction contains most of the vacuoles, mitochondria and nuclei . Upon the purification of vacuoles the PP is enriched to the same extent as are the vacuolar markers . The amount of PP per vacuole is comparable to the amount of PP per protoplast . The possibility that PP is located in the cell wall is also considered . In the course of the incubation necessary for preparing protoplasts, 20% of the cellular PP is broken down . As this loss of PP occurs to the same extent in the absence of cell wall degrading enzymes, it is inferred that internal PP is metabolically degraded, no PP being located in the cell walls . It is concluded that in Saccharomyces cerevisiae most if not all of the PP is located in the vacuoles, at least under the growth conditions used. Genetics, 1978 Mar, 88(3), 419 - 25 Twenty-six chromosomal genes needed to maintain the killer double-stranded RNA plasmid of Saccharomyces cerevisiae; Wickner RB; The double-stranded RNA killer plasmid gives yeast strains carrying it both the ability to secret a protein toxin and immunity to that toxin . This report describes a new series of mutants in chromsomal genes needed for killer plasmid maintenance (mak genes) . These mutants comprise 12 complementation groups . There are a total of at least 26 mak genes . Each mak gene product is needed for plasmid maintenance in diploids as well as in haploids . None of these mak mutations prevent the killer plasmid from entering the mak- spores in the process of meiotic sporulation . Complementation between mak mutants can be performed by mating meitoic spores from a makx/+ plasmid-carrying diploid with a maky haploid . If x = y, about half the diploid clones formed lose the killer plasmid . If x not equal to y, complementation occurs, and all of the diploid clones are killers. Biochim Biophys Acta, 1978 Mar 1, 539(2), 218 - 29 Biosynthesis and characterization of large dolichyl diphosphate-linked oligosaccharides in Saccharomyces cerevisiae; Lehle L et al.