S. cerevisiae

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.; Yeast membranes incorporate radioactivity from GDP{14C}mannose into various glycolipids . These can be separated by thin layer chromatography into at least seven components . The major component has been identified previously as dolichyl monophosphate mannose . Only one additional component is not sensitive to mild alkaline saponification, but is hydrolyzed instead under mild acidic conditions . This latter glycolipid has all the characteristics of a polyprenyl diphosphate oligosaccharide with a sugar moiety of more than 12 hexose units . It runs like dolichyl diphosphate derivatives on a DEAE column and evidence is presented that the lipid moiety is a polyprenol . When radioactive Dol-PP-di-N-acetylchitobiose is incubated with yeast membranes in the presence of non-radioactive GDPmannose a small amount of a larger lipid oligosaccharides is formed besides the previously-described Dol-PP-(GlcNAc)2 mannose . This oligosaccharide has all the properties of the glycolipid described above . Its formation is greatly increased when Triton is omitted from the incubation . Radioactivity of the polyprenyl diphosphate {14C}oligosaccharide is transferred to ethanol-insoluble material, most likely endogenous membrane glycoproteins.

J Bacteriol, 1978 Mar, 133(3), 1096 - 1107
Arginine metabolism in Saccharomyces cerevisiae: subcellular localization of the enzymes; Jauniaux JC et al.; Subcellular localization of enzymes of arginine metabolism in Saccharomyces cerevisiae was studied by partial fractionation and stepwise homogenization of spheroplast lysates . These enzymes could clearly be divided into two groups . The first group comprised the five enzymes of the acetylated compound cycle, i.e., acetylglutamate synthase, acetylglutamate kinase, acetylglutamyl-phosphate reductase, acetylornithine aminotransferase, and acetylornithine-glutamate acetyltransferase . These enzymes were exclusively particulate . Comparison with citrate synthase and cytochrome oxidase, and results from isopycnic gradient analysis, suggested that these enzymes were associated with the mitochondria . By contrast, enzymatic activities going from ornithine to arginine, i.e., arginine pathway-specific carbamoylphosphate synthetase, ornithine carbamoyltransferase, argininosuccinate synthetase, and argininosuccinate lyase, and the two first catabolic enzymes, arginase and ornithine aminotransferase, were in the "soluble" fraction of the cell.

Can J Microbiol, 1978 Mar, 24(3), 222 - 7
Effects of ethylene on the metabolism of Saccharomyces cerevisiae; Thomas KC et al.; Supply of exogenous ethylene to lactate-grown yeast initially accelerated the rate of ethanol production from glucose, but later reduced the rate, with the overall effect being to reduce the total ethanol production . The rate of ethanol production by ethylene-treated yeast was not changed by removal of metabolic carbon dioxide . However, if CO2 was allowed to build up in the absence of applied ethylene, the ethanol production decreased . Ethylene increased the activities of a number of pentose phosphate and glycolytic pathway enzymes . The largest increase in activity was observed for phosphofructokinase (EC 2.7.1.11), regulatory enzyme of the glycolytic pathway . After an initial stimulation, glucose (and also 3-O-methyl glucose) uptake was reduced by ethylene . Ethylene appears to inhibit non-competitively the glucose transport system.

J Bacteriol, 1978 Mar, 133(3), 1368 - 76
Glycerolipid biosynthesis in Saccharomyces cerevisiae: sn-glycerol-3-phosphate and dihydroxyacetone phosphate acyltransferase activities; Schlossman DM et al.; Yeast acyl-coenzyme A:dihydroxyacetone-phosphate O-acyltransferase (DHAP acyltransferase; EC 2.3.1.42) was investigated to (i) determine whether its activity and that of acyl-coenzyme A:sn-glycerol-3-phosphate O-acyltransferase (glycerol-P acyltransferase; EC 2.3.1.15) represent dual catalytic functions of a single membranous enzyme, (ii) estimate the relative contributions of the glycerol-P and DHAP pathways for yeast glycerolipid synthesis, and (iii) evaluate the suitability of yeast for future genetic investigations of the eucaryotic glycerol-P and DHAP acyltransferase activities . The membranous DHAP acyltransferase activity showed an apparent Km of 0.79 mM for DHAP, with a Vmax of 5.3 nmol/min per mg, whereas the glycerol-P acyltransferase activity showed an apparent Km of 0.05 mM for glycerol-P, with a Vmax of 3.4 nmol/min per mg . Glycerol-P was a competitive inhibitor (Ki, 0.07 mM) of the DHAP acyltransferase activity, and DHAP was a competitive inhibitor (Ki, 0.91 mM) of the glycerol-P acyltransferase activity . The two acyltransferase activities exhibited marked similarities in their pH dependence, acyl-coenzyme A chain length preference and substrate concentration dependencies, thermolability, and patterns of inactivation by N-ethylmaleimide, trypsin, and detergents . Thus, the data strongly suggest that yeast glycerol-P and DHAP acyltransferase activities represent dual catalytic functions of a single membrane-bound enzyme . Furthermore, since no acyl-DHAP oxidoreductase activity could be detected in yeast membranes, the DHAP pathway for glycerolipid synthesis may not operate in yeast.

J Biol Chem, 1978 Feb 25, 253(4), 1297 - 304
Characterization of two forms of asparaginase in Saccharomyces cerevisiae; Dunlop PC et al.; Saccharomyces cerevisiae X2180-1A synthesizes two forms of asparaginase: L-asparaginase I, an internal constitutive enzyme, and asparaginase II, an external enzyme which is secreted in response to nitrogen starvation . The two enzymes are biochemically and genetically distinct . The structural gene for asparaginase I (asp 1) is closely linked to the trp 4 gene on chromosome IV . The gene controlling the synthesis of asparaginase II is not linked to either the trp 4 or asp 1 genes . The rate of biosynthesis of asparaginase II is unaltered in yeast strains carrying the structural gene mutation for asparaginase I . Asparaginase II has been purified approximately 300-fold from crude extracts of Saccharomyces by heat and pH treatment, ethanol fractionation, ammonium sulfate fractionation followed by Sephadex G-25 chromatography, and DEAE-cellulose chromatography . Multiple activity peaks were obtained which, upon gas chromatographic analysis, exhibit varying mannose to protein ratios . Asparaginase I has been purified approximately 100-fold from crude extracts of Saccharomyces by protamine sulfate treatment, ammonium sulfate fractionation, gel permeation chromatography, and DEAE-cellulose chromatography . No carbohydrate component was observed upon gas chromatographic analysis . Comparative kinetic and analytic studies show the two enzymes have little in common except their ability to hydrolyze L-asparagine to L-aspartic acid and ammonia.

J Biol Chem, 1978 Feb 25, 253(4), 1086 - 9
The DNA untwisting enzyme from Saccharomyces cerevisiae . Partial purification and characterization; Durnford JM et al.; The DNA untwisting enzyme has been partially purified from Saccharomyces cerevisiae . The enzyme exhibits a pH optimum of 7.3 to 7.6 in phosphate buffer, appears to require 0.15 M KCl for activity as determined by a DNA filter-binding assay, and is inhibited by N-ethylmaleimide . Like the untwisting enzymes from other eucaryotic cells, it can remove both positive and negative superhelical turns . A DNA molecule containing a single strand break was shown to be an intermediate in the untwisting reaction . Thermal stabilities of the enzyme from selected conditional lethal mutants defective in DNA synthesis have been examined and were found to be indistinguishable from the wild type enzyme.

Biochim Biophys Acta, 1978 Feb 16, 517(2), 464 - 72
Factors influencing the observed half-lives of specific synthetic capacities in Saccharomyces cerevisiae; Cooper TG et al.; We have identified a variety of factors affecting the stability of allophanate hydrolase-specific and gross cellular protein synthetic capacities . These synthetic capacities have been extrapolated by many laboratories to represent functional messenger RNAs . Synthetic capacity turnover rates that we measured were greater in diploid organisms than in haploid strains and were proportional to the temperature of the culture medium . The stability of allophanate hydrolase-specific synthetic capacity was not influenced by alterations in the nitrogen source provided in the culture medium, but was increased up to 15-fold by the total inhibition of protein synthesis . Cultures in which protein synthesis was inhibited as little as 20% exhibited hydrolase-specific synthetic capacities more than 2-fold greater than those observed in the absence of inhibition.

Biochemistry, 1978 Feb 7, 17(3), 431 - 6
Possible site-specific reagent for the general amino acid transport system of Saccharomyces cerevisiae; Larimore FS et al.; The general amino acid transport system of Saccharomyces cerevisiae functions in the uptake of neutral, basic, and acidic amino acids . The amino acid analogue N-delta-chloroacetyl-L-ornithine (NCAO) has been tested as potential site specific reagent for this system . L-Tryptophan, which is transported exclusively by the general transport system, was used as a substrate . In the presence of glucose as an energy source, NCAO inhibited tryptophan transport competitively (Ki = 80 micrometer) during short time intervals (1-2 min), but adding 100 micrometer NCAO to a yeast cell suspension resulted in a time-dependent activation of tryptophan transport during the first 15 min of treatment . Following the activation a time-dependent decay of tryptophan transport activity occurred . Approximately 80% inactivation of the system was observed after 90 min . When a yeast cell suspension was treated with NCAO in the absence of an energy source, an 80% inactivation of tryptophan transport occurred in 90 min . The inactivation was noncompetitive (Ki congruent to 60 micrometer) and could not be reversed by the removal of the NCAO . Addition of a five-fold excess of L-lysine during NCAO treatment or prevented inactivation of tryptophan transport . Under parallel conditions of incubation, other closely related transport systems were not inhibited by NCAO.

Biochemistry, 1978 Feb 7, 17(3), 426 - 31
Saccharomyces cerevisiae DNA-dependent RNA polymerase III: a zinc metalloenzyme; Wandzilak TM et al.; Yeast nuclear RNA polymerase III was purified by batch adsorption to phosphocellulose, followed by ion-exchange chromatography on DEAE-Sephadex and affinity chromatography on DNA-Sepharose . Polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band which contained polymerase activity . The molecular weight estimated by sedimentation velocity centrifugation in a glycerol gradient was 380 000 . Enzyme activity was inhibited 50% at 0.1 mM 1,10-phenanthroline and 100% of 1.0 mM, but was restored when 1,10-phenanthroline was removed by dialysis . Enzyme activity was not inhibited by 7,8-benzoquinoline, a nonchelating structural analogue of 1,10-phenanthroline . These results strongly suggest that inhibition of enzyme activity occurs by the formation of a reversible enzyme-zinc-phenanthroline ternary complex . The zinc content, measured by atomic absorption spectroscopy, was 2 g-atoms per mol of enzyme . Zinc was not removed from the enzyme by gel filtration on Sephadex G-25, by passage through Chelex-100 resin, or by dialysis against buffer containing 1,10-phenanthroline . Enzyme-bound zinc was removed by dialysis after denaturation of the enzyme with heat and sodium dodecyl sulfate . Enzyme-bound zinc did not exchange with free zinc . These results establish yeast nuclear RNA polymerase III as a zinc metalloenzyme.

Genetika, 1978 Feb, 14(2), 328 - 33
{Genetic effects of the decay of tritium incorporated into Saccharomyces cerevisiae yeast cells . I . Lethal effect of 3H-alanine on cells of different ploidy and radiosensitivity}; Korolev VG et al.; Lethal effect of 3H-alanine on cells of different ploidy (1n-4n) and radiosensitivity wild type haploid and diploid strains; xrs2 mutant and diploid strains homozygous for this mutation is studied . It is shown that the efficiency of the inactivation per tritium decay depends on ploidy, radiosensitivity and geometric dimension of cells and nuclei . Do for all the studied strains is slightly higher than Do for these strains in case of external beta-irradiation . RBE of beta-ray tritium with respect to beta-ray of 32P is 1.5.

Mutat Res, 1978 Feb, 49(2), 195 - 201
Selection with cycloheximide of metabolic and UV-sensitive mutants of Schizophyllum commune and Saccharomyces cerevisiae; Shneyour Y et al.; The difference in lethality to cycloheximide between actively dividing and non-dividing cells was exploited to enhance detection of auxotrophic and UV-sensitive mutants in the fungi Schizophyllum commune and Saccharomyces cerevisiae.

J Bacteriol, 1978 Feb, 133(2), 692 - 8
Light effects in yeast: inhibition by visible light of growth and transport in Saccharomyces cerevisiae grown at low temperatures; Woodward JR et al.; Growth rate, sugar transport, and amino acid transport of yeast cells grown at 12 degrees C were inhibited by cool-white fluorescent light . At light intensities below 1,250 lx, growth and membrane transport were only slightly inhibited . Above 1,250 lx, there was increasing inhibition of both processes . Transport of histidine was completely inhibited after 3 to 5 days in cultures grown at 12 degrees C under 3,500-lx illumination . Cells grown at 20 degrees C were not inhibited by light intensities that caused complete loss of viability and membrane transport activity in cells grown at 12 degrees C.

Eur J Biochem, 1978 Feb 1, 83(1), 67 - 76
The malate dehydrogenase isoenzymes of Saccharomyces cerevisiae . Purification, characterisation and studies on their regulation; Hagele E et al.; 1 . One mitochondrial and one cytoplasmic malate dehydrogenase isoenzyme could be purified from acetate grown cells of the yeast Saccharomyces cerevisiae . 2 . The purification procedure uses chromatography on dextran blue columns as an essential step for enrichment, and reverse ammonium sulfate chromatography on celite for isoenzyme separation . 3 . The homogeneity of the preparations was established by gel electrophoreses in the presence of sodium dodecylsulfate and by a sedimentation run in the analytical ultracentrifuge . 4 . Both enzymes are dimers with a molecular weight of 75 000 for the cytoplasmic and of 68 000 for the mitochondrial enzyme . 5 . Amino acid analysis and peptide mapping showed that both enzymes are closely related, but genetically different (true isoenzymes) . 6 . The cytoplasmic enzyme shows electrophoretic splitting . This is most likely due to post-translational deamination in vivo . 7 . Antibodies to both isoenzymes could be obtained in rabbits . The antisera to cytoplasmic malate dehydrogenase were specific for this enzyme . Antisera to mitochondrial malate dehydrogenase react with both isoenzymes . Neither type of antisera precipitated an inactive protein after the glucose-dependent inactivation of cytoplasmic malate dehydrogenase in vivo.

Biochem J, 1978 Feb 1, 169(2), 343 - 53
Protein-lipid interactions in cytochrome oxidase from Saccharomyces cerevisiae . Effects of detergents and reconstitution of enzyme activity by phospholipids by using cholate-mediated exchange; Virji M et al.; Cytochrome oxidase, purified from the yeast Saccharomyces cerevisiae, was shown to have associated phospholipid, cholate or detergent, which could be varied by dialysis or (NH4)2SO4 precipitation of the protein . Cholate and the detergents Triton X-100 and Tween 80 were shown to differ in their ability to support enzyme activity . Changes in the Vmax, but not the Km, for ferrocytochrome c as the cholate concentration was varied indicate that cholate increases the number of exposed active sites of the enzyme . Cholate was used to introduce chosen phospholipids into the lipid environment of yeast cytochrome oxidase . Kinetic studies clearly showed that cholate can mediate exchange of exogenous for endogenous phospholipid . All phospholipids screened supported activity up to the basal value for the unsubstituted enzyme, whereas mitochondrial phosphatidylethanolamine and various phosphatidlycholines (except 1,2-dipalmitoyl-sn-glycero-3-phosphocholine) produced enhanced activity . A detailed kinetic examination revealed that the major effect of phosphatidylethanolamine is to increase k+1, whereas the major effect of phosphatidylcholine is to increase K+2 in the minimal kinetic scheme E + S k+1 in equilibrium k-1 ES k+2 leads to E + P Cardiolipin, although supporting activity, does not give any enhancement of k+1 or k+2 over the values for the cholate control . The relevance of these observations to protein-lipid interactions in cytochrome oxidase is discussed.

J Biol Chem, 1978 Jan 10, 253(1), 305 - 10
Heme is necessary for the accumulation and assembly of cytochrome c oxidase subunits in Saccharomyces cerevisiae; Saltzgaber-Muller J et al.; The presence of cytochrome c oxidase subunits and the association of these subunits with each other was studied in a heme-deficient Saccharomyces cerevisiae mutant . This mutant had been isolated by Gollub et al . (1977) J . Biol . Chem . 252, 2846-2854) and had been shown lack delta-aminolevulinic acid synthetase . When grown in the absence of heme or heme precursors, the mutant is respiration-deficient, devoid of cytochrome absorption bands and auxotrophic for all those components whose biosynthesis is dependent on hemoproteins; when grown in the presence of heme or heme precursors, the mutant is phenotypically wild type . Upon growth of the mutant in the absence of heme synthesis, the mitochondria still contained two of the three mitochondrially made cytochrome c oxidase subunits (i.e . II and III) and at least one of the cytoplasmically made cytochrome c subunits (VI) . The other subunits were either barely detectable (I, IV) or undetectable (V, VII) . The residual subunits were apparently not assembled with each other since an antiserum directed mainly against Subunit VI failed to co-precipitate Subunits II and III which were still present . In contrast, growth of the mutant in the presence of delta-aminolevulinic acid led to the accumulation of active, fully assembled cytochrome c oxidase in the mitochondria . Heme a (or one of its precursors) thus controls the assembly of cytochrome c oxidase from its individual subunits.

Eur J Biochem, 1978 Jan 2, 82(1), 33 - 43
On the mechanism of substrate binding to the purine-transport system of Saccharomyces cerevisiae; Foret M et al.; The yeast Saccharomyces cerevisiae takes up adenine, guanine, hypoxanthine, and cytosine via a common energy-dependent transport system . The apparent affinity of the transport system to these and other purines and pyrimidines is correlated with their capability to be protonated to the positively charged form . Further organic molecules are competitive inhibitors when they are cationic, e.g . guanidine and octylguanidine in contrast to urea, or hexadecyltrimethylammonium in contrast to dodecylsulfate and Triton X-100 . The influence of the pH on the kinetic constants of hypoxanthine transport points to a stoichiometry of one proton being associated to the transport system together with one substrate molecule . The pKa values of two ionizable groups that are involved in substrate binding are revealed; one of which (pKa = 1.8) may be attributed to the substrate, the other (pKa = 5.1) to an amino acid residue in the recognition site of the transport system . Studies with group-specific inhibitors indicate that this amino acid residue contains a carboxyl group . The results are in accordance with the assumption that a carboxyl group of the transport system, a proton and a substrate molecule arrange to an uncharged ternary complex.

Microbios, 1978, 21(85-86), 161 - 76
Virus-like particles and double stranded RNA from killer and non-killer strains of Saccharomyces cerevisiae; Harris MS; Virus-like particles and DsRNA found in extracts of killer, non-killer and suppressive non-killer strains were co-precipitated from cell extracts using an antibody prepared against purified virus-like particles isolated from a non-killer strain having only the higher molecular weight L dsRNA . The relative amount of virus-like particles correlated roughly with the amount of dsRNA: those strains with high concentrations of dsRNA had the most particles . When a preparation of particles was subjected to sucrose gradient velocity centrifugation, particles containing the S and M dsRNA could be separated from those containing the L dsRNA . These experiments taken together suggest that the L, M and S dsRNAs are separately encapsulated by the same protein coat.

Antonie Van Leeuwenhoek, 1978, 44(2), 183 - 92
Biosynthesis of Saccharomyces cerevisiae glycoproteins: nature of some participating glycolipids; Dominguez A et al.; A particulate membrane preparation from Saccharomyces cerevisiae catalyzed the incorporation of mannose from GDP-mannose into lipids that were extractable in chloroform-methanol . One lipid has been previously characterized as dolichyl phosphomannose . Another one was purified by chromatography on silicic acid, DEAE-cellulose and Sephadex LH-20 was found to be alkali unstable . The lipid moiety was shown to be dolichol and the glycosydic part contained mannose, glucose and glucosamine . Radioactive mannose was also incorporated at a slower rate into more polar compounds . They were soluble in chloroform-methanol-water and were seen to liberate neutral oligosaccharides after alkaline hydrolysis . Radioactive mannose was also incorporated into substances which behave chemically as glycoproteins since they were insoluble in organic solvents, water and trichloroactic acid . Pronase treatment of the trichloroacetic acid-insoluble material released water-soluble oligosaccharides . When the particulate preparation which had been extracted with chloroform-methanol at-20 C, was incubated with GDP-(U-14C)mannose, radioactivity was incorporated into glycolipids that were soluble in chloroform-methanol-water and into glycoproteins . This result suggests that at least part of the mannose was transferred to endogenous acceptors independent of dolichyl phosphomannose.

Folia Microbiol (Praha), 1978, 23(5), 372 - 5
Changes in the lipid content during cell division of Saccharomyces cerevisiae; Cejkova A et al.; Changes in the concentration of lipids were followed in synchronously dividing cells of Saccharomyces cerevisiae . Cell division was found to induce a pronounced increase in the concentration of sterols and changes in the concentrations of other types of lipids . The changes associated with the division process are only transient.

Folia Microbiol (Praha), 1978, 23(4), 286 - 91
Stimulation of amino acid transport in Saccharomyces cerevisiae by metabolic inhibitors; Horak J et al.; Inhibitors of energy metabolism (3-chlorophenylhydrazonomalononitrile, antimycin A, iodoacetamide, dicyclohexylcarbodiimide) but not of transport (uranyl ions) stimulate at low concentrations the uptake of L-leucine, L-glutamic acid, L-arginine and, to a lesser degree, of 2-aminoisobutyric acid in Saccharomyces cerevisiae . The effect is apparent only after augmenting the energy reserves of cells by preincubation with D-glucose or, more strikingly, with ethanol . It is absent in a mutant (op1) lacking the translocation system for ADP--ATP in mitochondria . The presence of two different energy reserves for amino acid transport is indicated (one in energy-poor, the other in energy-rich cells) . The stimulating effect appears to be caused by a retarded degradation of the transport proteins as occurs at a lowered level of mitochondria-produced ATP.

Z Allg Mikrobiol, 1978, 18(4), 275 - 9
Kinetics of petite mutation and thermal death in Saccharomyces cerevisiae growing at superoptimal temperatures; Simoes-Mendes B et al.; Mass formation of petite mutants took place in a strain of Saccharomyces cerevisiae when grown at superoptimal temperatures . After an initial period of exponential growth, a second period followed during which exponential death and net exponential petite mutation concurred with exponential growth . The specific rates of the three exponential processes were of the same order of magnitude and varied with the temperature . Net exponential petite mutation did not occur during the deathless first period of growth at superoptimal temperatures nor at any time during growth at suboptimal temperatures . Mitochondria are discussed as possible targets of thermal death in mesophilic yeasts.

Folia Microbiol (Praha), 1978, 23(3), 216 - 24
The effect of ultrasound and its combination with radiation on the genetic material of Saccharomyces cerevisiae; Silhankova L et al.; Ultrasonication at 20 kHz, intensity 35 W/cm2 and amplitude 15--25 micron of a diploid strain of Saccharomyces cerevisiae was found to act as a weak mutagen with maximum efficiency at the 20% survival of the cells . Under these conditions, the frequency of reversion of the suppressible allel ilv1-92 increased ten times, the frequency of mitotic gene conversion four times . Doses leading to survivals lower than 20% led to a slight increase in the frequency of cytoplasmic respiration-deficient mutants . Submutagenic doses applied immediately after gammaradiation or UV light did not substantially increase the effect of these physical agents on the genetic material of the yeast strain investigated . Application of ultrasound prior to UV radiation did not considerably influence the effect of the radiation either.

Biokhimiia, 1978, 43(4), 662 - 8
{Proteolysis of products of mitochondrial protein synthesis in isolated mitochondria of Saccharomyces cerevisiae yeasts}; Kal'nov SL et al.; Products of mitochondrial protein synthesis were specifically labeled with 3H-leucine in the presence of cycloheximide at the end of the exponential phase of yeast aerobic growth on glucose . The mitochondria isolated from these cells lost 37-40% of the label from the protein fraction during 60 min incubation at 35 degrees, which was accompanied by the accumulation of 3H-leucine in TCA-soluble fraction . This process was suppressed by phenyl-methyl sulfonyl fluoride and p-chloromercuriphenyl sulfonate, the inhibitors of proteases, and could thus be considered as the proteolysis of the products of mitochondrial protein synthesis . The proteolysis was ATP dependent and was stimulated by puromycine which is known to induce the removal of incomplete polypeptides from mitochondrial ribosomes . A body of indirect evidence allows a suggestion to be made that the observed proteolysis can hardly be due to the action of cytoplasmic proteinases.

Antonie Van Leeuwenhoek, 1978, 44(1), 25 - 34
Inositol deficiency in Saccharomyces cerevisiae NCYC 86; Dominguez A et al.; When Saccharomyces cerevisiae NCYC 86, an inositol dependent strain, is grown at suboptimal concentrations of inositol, the buds are apparently unable to separate from the parent cells . Thin sections of such cells show an irregularly thickened cell wall . These morphological features may be due to a continuation or increase in the production of glucan while the synthesis of DNA, RNA, phospholipids.and protein is greatly inhibited.

Mikrobiologiia, 1978 Jan-Feb, 47(1), 51 - 5
{Characteristics of the metabolism and multiplication of dehydrated Saccharomyces cerevisiae yeasts during their reactivation}; Meledina TV et al.; The growth of dehydrated and original cells of Saccharomyces cerevisiae 0-14 was studied in the conditions of reactivation . The identical amount of biomass having the economical growth coefficient of 58-59 percent was accumulated in both variants after 6 hours of growth . The composition and quantitative proportions between free amino acids were studied in the cells of the two cultures . Dehydrated cells lost up to 10 per cent of free amino acids in the course of rehydration . The dynamics of changes in the composition of the amino acid pool in rehydrated dry cells differed from that in pressed yeast cells . By the end of reactivation however, the qualitative composition and the level of the amino acid pool were similar in the cells of the two variants . The yield of growth of reactivated cells in the course of following cultivation was by 16 per cent higher than that of pressed yeast cells grown under the same conditions.

Folia Microbiol (Praha), 1978, 23(5), 349 - 50
alpha-Mannosidases of genera Aspergillus and Rhizopus . Activity and capacity to utilize Saccharomyces cerevisiae mannan of the best alpha-mannosidase producer Aspergillus flavus Link 69; Augustin J et al.; Strains of fungi imperfecti of genera Aspergillus and Rhizopus were tested for the ability to produce alpha-mannosidases . The most suitable alpha-mannosidase producer of a total of 20 strains under study was Aspergillus Ravus Link 69 . The parameters studied during the cultivation included the growth rate expressed as cell dry weight, alpha-mannosidase activity of the extracellular medium with p-nitorphenyl alpha-D-mannopyranoside as substrate, and utilization of Saccharomyces cerebisiae mannan via its disappearance from the cultivation medium.

Acta Microbiol Pol, 1978, 27(3), 193 - 202
Respiratory mutation and galactose metabolism in yeast Saccharomyces cerevisiae; Bien M et al.; Restriction in growth on galactose as unique source of energy due to respiratory deficiency resulting from mutation in a gene gal probably different from gal 3 is described.

J Biol Chem, 1977 Dec 25, 252(24), 9010 - 7
Translation of the L-species dsRNA genome of the killer-associated virus-like particles of Saccharomyces cerevisiae; Hopper JE et al.; Virus-like particles containing the L (P1)-species of double-stranded RNA (dsRNA) were isolated from Saccharomyces cerevisiae, and the translational activity of the virus-like particle-derived dsRNA was analyzed in the wheat germ cell-free system . Denaturation of the dsRNA immediately prior to in vitro translation resulted in the synthesis of one major and at least three minor polypeptides, whereas undenatured dsRNA, as expected, did not stimulate {35S}methionine incorporation into polypeptides, but actually slightly inhibited endogenous activity . The major in vitro translation product of the denatured L-dsRNA was shown to be identical with the major L-dsRNA containing virus-like particle capsid polypeptide on the basis of three criteria: co-electrophoresis on sodium dodecyl sulfate polyacrylamide gels, immunoprecipitation, and tryptic peptide analysis . We have therefore established that the L-dsRNA genome encodes the major virus-like particle capsid polypeptide . This result adds considerable support to the hypothesis that the L-dsRNA genome acts as a helper genome to the smaller (1.6 x 10(6) dalton) M-dsRNA genome in killer strains of yeast by providing the M-dsRNA containing virus-like particles with their major coat protein.

Biochim Biophys Acta, 1977 Dec 22, 500(2), 372 - 84
Biosynthesis of beta-glucans by cell-free extracts from Saccharomyces cerevisiae; Lopez-Romero E et al.; Cell-free extracts from Saccharomyces cerevisiae catalyzed the incorporation of glucosyl residues from UDP-{U-14C}glucose into beta-1,3-glucans which contained a significant proportion of beta-1,6-glycosidic linkages . When GDP-{U-14C}glucose was used as substrate only trace amounts of glucose were incorporated . Activity of beta-glucan synthetase was distributed among membrane and cell wall fractions, specific activity being higher in this latter . Beta-glucan synthesized by membrane and cell wall fractions contained 0.6% and 2.5% of beta-1,6-glycosidic linkages respectively . A marked decrease in the activity of beta-glucan synthetase occurred as the cells aged . Significant activity of glycogen synthetase was detected only in cells which had reached the stationary phase of growth.

J Biol Chem, 1977 Dec 10, 252(23), 8684 - 91
Changes in phospholipids of Saccharomyces cerevisiae associated with inositol-less death; Becker GW et al.; Two inositol-requiring strains of Saccharomyces cerevisiae were examined for changes in levels of phospholipids occurring after inositol deprivation . Lack of inositol results in loss of cell viability (inositol-less death) and in very large increases in two phospholipid precursors, phosphatidic acid and CDP-diacylglycerol; the accumulation of other glycerophospholipids continues for a considerable time at normal rates . Phosphatidylinositol accumulation does not occur in the absence of inositol; however, the further metabolism of this lipid continues, with 80 to 90% of this lipid disappearing . This disappearance is matched by increases in the phosphoinositol containing sphingolipids and extracellular glycerophosphoinositol . These changes are not observed when growth is blocked by cycloheximide or by omission of lysine from a lysine auxotroph, most lipids continuing to accumulate long after growth stops . There appears to be no close coordination in the synthesis of the major yeast phospholipids or between protein synthesis and phospholipid synthesis . However, despite very large changes in the composition of yeast phospholipids that can be achieved by altering culture conditions, it appears that the average charge per phospholipid molecule remains fairly constant.

Mol Gen Genet, 1977 Dec 9, 157(3), 327 - 32
Synthesis and turnover of ribosomal proteins in the absence of 60S subunit assembly in Saccharomyces cerevisiae; Gorenstein C et al.; We have measured the synthesis and stability of ribosomal proteins in a temperature sensitive strain of yeast which at the restrictive temperature is specifically blocked in the processing of 27S ribosomal precursor RNA . We find that in the absence of 60S ribosomal subunit assembly, the synthesis of all the ribosomal proteins studied continued . However, the proteins of the 60S subunit fail to accumulate and are rapidly degraded.

J Biochem (Tokyo), 1977 Dec, 82(6), 1689 - 93
Degradation of mating factor by alpha-mating type cells of Saccharomyces cerevisiae; Tanaka T et al.; The change of the mating factor activity during the culture of Saccharomyces cerevisiae X-2180 1B, an alpha-mating type haploid strain, were followed . The activity increased rapidly during the exponential phase of growth, reached a maximum during the early stationary phase and then decreased . Oligopeptides comprising partial sequences of the mating factor were isolated from the culture fluids at various phases of cell growth . We concluded that the mating factor, a tridecapeptide, was degraded during culture into two peptides, Trp-His-Trp-Leu-Gln-Leu and Lys-Pro-Gly-Gln-Pro-Met-Tyr, by cleavage of the peptide bond between Leu-6 and Lys-7 of the mating factor . A dodecapeptide lacking the N-terminal Trp residue was not detected at any stage of cell growth examined.

J Biochem (Tokyo), 1977 Dec, 82(6), 1681 - 7
Purification and amino acid sequence of mating factor from Saccharomyces cerevisiae; Tanaka T et al.; Mating factor is a peptide excreted into the culture fluid by alpha-mating type cells of Saccharomyces cerevisiae X-2180 1B . The purification of the mating factor was carried out by ion exchange chromatography on phosphocellulose and Amberlite IRC 50 columns, followed by gel filtration on a Sephadex LH 20 column . The factor thus prepared was a peptide composed of Lys1, His1, Trp2, Gln2, Pro2, Gly1, Met1, Leu2 and Tyr1, and was able to induce morphological changes on alpha-mating type cells at a concentration of 5 pg/ml . The amino acid sequence of the mating factor was determined by the manual Edman degradation method using intact mating factor and its thermolytic peptides . The C-terminal amino acid residue was determined by digesting the factor with carboxypeptidase A . The complete amino acid sequence of the mating factor was established to be as follows: Trp-His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr.

J Bacteriol, 1977 Dec, 132(3), 806 - 17
Osmotic imbalance in inositol-starved spheroplasts of Saccharomyces cerevisiae; Atkinson KD et al.; Physiological states associated with inositol starvation of spheroplasts of Saccharomyces cerevisiae were investigated and compared with conditions preceding death of starved whole cells . In the absence of synthesis of inositol-containing lipids, cell surface expansion terminated after one doubling of whole cells . In spheroplasts, cessation of membrane expansion was apparently followed by rapid development of an osmotic imbalance, causing lysis . Continued synthesis and accumulation of cytoplasmic constituents within the limited cell volume were implicated as a cause of the osmotic imbalance . In whole cells, an increase in internal osmotic pressure also follows termination of membrane and cell wall expansion . The cell wall prevents lysis, allowing a state of increasing cytoplasmic osmotic pressure to persist in the period preceding onset of inositol-less death.

J Biol Chem, 1977 Nov 25, 252(22), 8212 - 6
Identification of a pyruvoyl residue in S-adenosylmethionine decarboxylase from Saccharomyces cerevisiae; Cohn MS et al.; S-Adenosylmethionine decarboxylase from Saccharomyces cerevisiae has been purified to homogeneity . Acid hydrolysis of NaB3H4-reduced enzyme released 2.2 mol of tritiated lactate per mol of dimeric enzyme, indicating that a pyruvate moiety is present . Inhibition of enzymatic activity by NaBH4 reduction and by carbonyl-binding reagents indicates that this pyruvoyl residue is required for the activity of the enzyme . This is the first example reported of a eukaryotic enzyme containing a covalently linked pyruvoyl residue.

J Biol Chem, 1977 Nov 25, 252(22), 8126 - 35
Ribosomal RNA genes of Saccharomyces cerevisiae . II . Physical map and nucleotide sequence of the 5 S ribosomal RNA gene and adjacent intergenic regions; Valenzuela P et al.; A DNA fragment containing the structural gene for the 5 S ribosomal RNA and intergenic regions before and after the 35 S ribosomal RNA precursor gene of Saccharomyces cerevisiae has been amplified in a bacterial plasmid and physically mapped by restriction endonuclease cleavage and hybridization to purified yeast 5 S ribosomal RNA . The nucleotide sequence of the DNA fragments carrying the 5 S ribosomal RNA gene and adjacent regions has been determined . The sequence unambiguously identifies the 5 S ribosomal RNA gene, determines its polarity within the ribosomal DNA repeating unit, and reveals the structure of its promoter and termination regions . Partial DNA sequence of the regions near the beginning and end of the 35 S ribosomal RNA gene has also been determined as a preliminary step in establishing the structure of promoter and termination regions for the 35 S ribosomal RNA gene.

J Biol Chem, 1977 Nov 25, 252(22), 8118 - 25
Ribosomal RNA genes of Saccharomyces cerevisiae . I . Physical map of the repeating unit and location of the regions coding for 5 S, 5.8 S, 18 S, and 25 S ribosomal RNAs; Bell GI et al.; The organization of the ribosomal DNA repeating unit from Saccharomyces cerevisiae has been analyzed . A cloned ribosomal DNA repeating unit has been mapped with the restriction enzymes Xma 1, Kpn 1, HindIII, Xba 1, Bgl I + II, and EcoRI . The locations of the sequences which code for 5 S, 5.8 S, 18 S, and 25 S ribosomal RNAs have been determined by hybridization of the purified RNA species with restriction endonuclease generated fragments of the repeating unit . The position of the 5.8 S ribosomal DNA sequences within the repeat was also established by sequencing the DNA which codes for 83 nucleotides at the 5' end of 5.8 S ribosomal RNA . The polarity of the 35 S ribosomal RNA precursor has been established by a combination of hybridization analysis and DNA sequence determination and is 5'-18 S, 5.8 S, 25 S-3'.

Mol Gen Genet, 1977 Nov 18, 156(3), 319 - 26
Genetics and biochemistry of cryptopleurine resistance in the yeast Saccharomyces cerevisiae; Sanchez L et al.; Protein synthesis by ribosomes from several cryptopleurine-resistant yeast mutants is also resistant to emetine and tubulosine . These mutants can be classified into two different types: Class I mutants which display high levels of resistance to emetine and tubulosine and Class II mutants that are only weakly resistant to tubulosine and are slightly more sensitive to emetine than those of Class I . Apparently all mutants have similar levels of resistance to cryptopleurine . The distinct phenotypes of Class I and Class II strains are expressed through their 40S ribosomal subunit . Genetic analysis has shown that the mutations to cryptopleuring resistance are allelic and that in a particular case (strain CRY6) the pleiotropic phenotype is a result of the expression of the cry1 locus . It is suggested that Class I and Class II mutants arise from two independent mutational events within The cry1 allel . In heterozygous (+/cry1) diploids both the sensitive and the resistant genes are expressed as shown by studies of the action of cryptopleurine on polyphenylalanine-synthesizing systems derived from each parental sensitive and resistant haploid strain and heterozygous diploid strains . The apparent dominance of sensitivity over resistance which may be observed in vivo in heterozygous (+/cry1) diploids has been explained in terms of the mode of action of the inhibitors.

Mol Gen Genet, 1977 Nov 4, 156(1), 79 - 85
Mapping of the two mitochondrial antimycin A resistance loci in Saccharomyces cerevisiae; Michaelis G et al.; Retention or loss of the two new mitochondrial antimycin A resistance loci AI and AII has been analyzed in a large number of stable cytoplasmic petite mutants . Using these deletion mutants it was possible to localize the two antimycin A resistance loci in the OI--OII region of mitochondrial DNA . The genetic loci are mapped in the following order: OII--AI--AII--cobl--OI . The mapping relationship of mutants resistant to antimycin A or funiculosin to various cob mutants is described.

Mol Gen Genet, 1977 Nov 4, 156(1), 55 - 60
Genetic studies with a phosphoglucose isomerase mutant of Saccharomyces cerevisiae; Maitra PK et al.; A mutation pgi1 in the yeast Saccharomyces cerevisiae conferring deficiency of the glycolytic enzyme glucose 6-phosphate isomerase is characterised genetically . The mutation segregates 2+:2- in tetrads from diploids heterozygous for the mutant phenotype . The mutation is semi-dominant and is located on the right arm of chromosome II in the order: tsm134--lys2--pgi1--tyr1 approximately 15 map units from tyr1 . The mutation pgi1 defines the structural gene of glucose 6-phosphate isomerase and can be suqpressed intragenically giving revertants that have an unstable enzyme . In one temperature-sensitive revertant no enzyme activity in excess of the mutant level could be detected although fructose 6-phosphate was converted to glucose 6-phosphate in vivo . The suppressor locus in this revertant is dominant and is unlinked to the pgi1 locus.

Biochim Biophys Acta, 1977 Nov 2, 479(1), 119 - 21
A comparison of small circular DNA molecules in psi+ and psi- strains of Saccharomyces cerevisiae; McCready SJ et al.; The psi+ and psi- phenotypes, which affect the efficiency of ochre suppression in yeast, are inherited in a non-Mendelian fashion . There is no apparent difference in length or in length distribution of 2 micronm circular DNA molecules between psi+ and psi- strains . It seems that the psi genetic determinant is probably not connected with the presence or absence of these small circular DNA molecules.

J Cell Biol, 1977 Nov, 75(2 Pt 1), 355 - 65
Regulation of mating in the cell cycle of Saccharomyces cerevisiae; Reid BJ et al.; The capacity of haploid a yeast cells to mate (fuse with a haploid strain of alpha mating type followed by nuclear fusion to produce a diploid cell) was assessed for a variety of temperature-sensitive cell division cycle (cdc) mutants at the permissive and restrictive temperatures . Asynchronous populations of some mutants do not mate at the restrictive temperature, and these mutants define genes (cdc 1, 4, 24, and 33) that are essential both for the cell cycle and for mating . For most cdc mutants, asynchronous populations mate well at the restrictive temperature while populations synchronized at the cdc block do not . Populations of a mutant carrying the cdc 28 mutation mate well at the restrictive temperature after synchronization at the cdc 28 step . These results suggest that mating can occur from the cdc 28 step, the same step at which mating factors arrest cell cycle progress . The cell cycle interval in which mating can occur may or may not extend to the immediately succeeding and diverging steps (cdc 4 and cdc 24) . High frequency mating does not occur in the interval of the cell cycle extending from the step before the initiation of DNA synthesis (cdc 7) through DNA synthesis (cdc 2, 8, and 21), medial nuclear division (cdc 13), and late nuclear division (cdc 14 and 15).

Prikl Biokhim Mikrobiol, 1977 Nov-Dec, 13(6), 893 - 900
{Relationship between the content of some fractions of high molecular weight polyphosphates and total nucleic acids upon dehydration of the yeast Saccharomyces cerevisiae}; Kulaev IS et al.; Essential redistribution of various polyphosphate fractions was shown during dehydration and subsequent reactivation of Saccharomyces cerevisiae 14 . Dehydration no matter what method was used, was followed by an increase in the content of acid soluble polyphosphates (fraction Poly P1) and a decrease of that of salt soluble polyphosphates (fraction Poly P2) . Reactivation of dehydrated yeast was, on the contrary, accompanied by a decrease in the PP 1 and an increase in the Poly P2 content . A direct correlation between the Poly P2 fraction and total nucleic acids was demonstrated under various conditions of dehydration and subsequent reactivation . An inverse correlation between the content of the Poly P2, fraction and nucleic acids, on the one hand, and that of the Poly P1 fraction, on the other, was observed . Study of activities of polyphosphatases, tripolyphosphatase, pyrophosphatase and ATPase in dehydrated yeast showed values similar to those in original cells.

J Bacteriol, 1977 Nov, 132(2), 738 - 9
Cell size and budding during starvation of the yeast Saccharomyces cerevisiae; Johnston GC; When starved for nitrogen, cells of the yeast Saccharomyces cerevisiae produced abnormally small cells . Nonetheless, during starvation, only cells of a size characteristic of growing cells were capable of initiating a bud . Even when growth was severely limited, some event(s) in G1 required growth to a critical size for completion.

J Bacteriol, 1977 Nov, 132(2), 723 - 30
Growth and cell division during nitrogen starvation of the yeast Saccharomyces cerevisiae; Johnston GC et al.; During nitrogen starvation, cells of the yeast Saccharomyces cerevisiae increased threefold in number, and little ribonucleic acid (RNA) and protein were accumulated . Both RNA and protein were extensivley degraded during starvation, suggesting that intracellular macromolecules could supply most of the growth requirements . The types and proportions of stable RNA synthesized during nitrogen deprivation were characteristic of exponentially growing cells; however, the complement of proteins synthesized was different . We conclude that, once events in the deoxyribonucleic acid division cycle are initiated, cells can complete division with little dependence on continued net cell growth.

J Bacteriol, 1977 Nov, 132(2), 462 - 72
a-Factor from Saccharomyces cerevisiae: partial characterization of a mating hormone produced by cells of mating type a; Betz R et al.; Conjugation between haploid cells of Saccharomyces cerevisiae is mediated through the action of diffusible mating hormones, two of which have been designated as a-factor and alpha-factor . Partially purified fractions exhibiting a-factor activity have been obtained from culture filtrates of a cells by ultrafiltration, ion-exchange chromatography, and gel filtration . The a-factor preparations specifically caused both G1 arrest and morphological alterations in cells of alpha-mating type, whereas a cells, a/alpha diploids, and nonmating alpha mutants were not affected . The a-factor activity was found in the culture filtrates of all a strains tested, but not in filtrates of alpha or a/alpha cell cultures . The hormone is sensitive to various proteases, showing that it is associated with a peptide or protein . Gel filtration studies suggest an apparent molecular weight greater than 600,000; however, this result may be due to aggregation with carbohydrate present in the preparations . Although the biological activities of a-factor are analogous to those described previously for alpha-factor, the chemical properties of these two hormones appear to be quite different.

Ann Microbiol (Paris), 1977 Nov-Dec, 128B(4), 439 - 50
{Study of PLi genes action on the cell wall structure of "Saccharomyces cerevisiae" Hansen (author's transl)}; Delpech I et al.; A study of the composition of cell walls extracted from a wild strain and three mutant strains "smooth colony" of Saccharomyces cerevisiae had been done . It points out differences in the mannose/glucose ratio and in the concentration of some other components of the cell wall in the mutant strains . The immunological study of the cell wall shows that "smooth colonies" mutants and wild strains differs in their mannoproteins.

Biophys J, 1977 Oct, 20(1), 15 - 22
Midcycle doubling of uptake rates of adenine and serine in Saccharomyces cerevisiae; Kubitschek HE et al.; Rates of uptake of serine and of adenine were measured as a function of cell size, and therefore age, in asynchronous, exponential phase cultures of diploid Saccharomyces cerevisiae strain Y55 . In both cases, uptake rates were constant during the initial third of the cell cycle and doubled during the S period in the middle part of the cycle to a constant value during the final third . Cell size and age at mid-step doubling were indistinguishable for serine and adenine uptake, and occurred during the period of DNA synthesis . The results extend an earlier hypothesis of constancy of cell growth rates (mass accumulation rates) and rates of uptake of all or almost all compounds into cells in exponential phase growth to one of piecewise constancy, with an abrupt doubling of growth and uptake rates during DNA synthesis.

Genetics, 1977 Oct, 87(2), 229 - 36
Increased spontaneous mitotic segregation in MMS-sensitive mutants of Saccharomyces cerevisiae; Prakash S et al.; Methyl methanesulfonate (MMS)-sensitive mutants of Saccharomyces cerevisiae belonging to four different complementation groups, when homozygous, increase the rate of spontaneous mitotic segregation to canavanine resistance from heterozygous sensitive (canr/+) diploids by 13-to 170-fold . The mms8-1 mutant is MMS and X-ray sensitive and increases the rate of spontaneous mitotic segregation 170-fold . The mms9-1 and mms13-1 mutants are sensitive to X rays and UV, respectively, in addition of MMS, and increase the rate of spontaneous mitotic segregation by 13-fold and 85-fold, respectively . The mutant mms21-1 is sensitive to MMS, X rays and UV and increases the rate of spontaneous mitotic segregation 23-fold.

Arch Microbiol, 1977 Sep 28, 114(3), 287 - 8
Temperature-sensitive loss of sexual agglutinability in Saccharomyces cerevisiae; Doi S et al.; Temperature dependency of sexual agglutination in Saccharomyces cerevisiae was found . Of 31 strains tested, which showed normal agglutination when cultured at 25 degrees C, 29 strains lost their sexual agglutinability when they were grown at 37 degrees C.

Mol Gen Genet, 1977 Sep 21, 155(1), 27 - 34
Analysis of mitochondrial ribosomal proteins of Saccharomyces cerevisiae by two dimensional polyacrylamide gel electrophoresis; Faye G et al.; Proteins from mitochondrial ribosomes of Saccharomyces cerevisiae were analysed by a two dimensional gel electrophoresis method . Each ribosomal subunit revealed a reproducible characteristic pattern of protein components . The 37S small subunit contained 33 protein species with an average molecular weight of 27,300 daltons (ranging from 60,000 to 95000 daltons) . The 50S large subunit showed 38 protein species with an average molecular weight of 23,000 (ranging from 41,000 to 10,000 daltons) . Ribosomes from various sources were compared on the basis of protein composition.

Biochem J, 1977 Sep 15, 166(3), 559 - 63
The effects of altered sterol composition on the mitochondrial adenine nucleotide transporter of Saccharomyces cerevisiae; Haslam JM et al.; 1 . The membrane sterol composition of mitochondria of the ole-3 mutant of Saccharomyces cerevisiae was manipulated by growing the organism in the presence of Tween 80 (1%, W/V) plus defined supplements o- delta-aminolaevulinate . 2 . Changes in mitochondrial sterol content induced considerable changes in the adenine nucleotide transporter . 3 . As the sterol content was decreased, the affinity of the transporter for ATP did not alter significantly, but the rate of ATP uptake was greatly decreased, the total number of atractylate-sensitive binding sites diminished, and the proportion of high-affinity binding sites was decreased . 4 . Since sterol depletion also uncouples oxidative phosphorylation {Astin & Haslam (1977) Biochem . J., 166, 287-298} and prevents the intramitochondrial generation of ATP, the decrease in the rate of ATP uptake by sterol-depleted mitochondria will cause a decrease in intramitochondrial ATP concentrations in vivo . This probably explains the inhibition of mitochondrial macromolecular synthesis that has previously been reported in lipid-depleted yeast mitochondria.

Mol Gen Genet, 1977 Sep 9, 154(3), 255 - 62
Fine structure physical mapping of 4S RNA genes on mitochondrial DNA of Saccharomyces cerevisiae; Van Ommen GJ et al.; We have localized the genes for mitochondrial 4S RNA on the physical map of the mtDNA of several Saccharomyces cerevisiae strains by hybridization of iodinated 4S RNA to the restriction fragments obtained with endonucleases HindII + III, EcoRI and HapII . The data indicate that 5-8 of the 4S RNA genes are dispersed over a large area of the genome whereas the rest (about 18 genes) is located within an area of about 9000 bp in length (about 18 genes) is located within an area of about 9000 bp in length (about 12% of the genome) between the markers for chloramphenicol and paromomycin resistance (RIB 1 and PAR 1 loci) . Within this region a cluster is present of 5 genes on a DNA fragment of 460 bp.

Mol Gen Genet, 1977 Sep 9, 154(3), 269 - 77
Ertosterol biosynthesis in Saccharomyces cerevisiae: mutants deficient in the early steps of the pathway; Karst F et al.; Thermosensitive mutants, auxotrophic for ergosterol synthesis, have been isolated, analyzed genetically and their enzymatic deficiencies investigated . These mutants were classified into seven unlinked complementation groups . These groupes lack the following enzymatic activities: squalene epoxidase (erg 1), 2,3-oxidosqualene-lanosterol cyclase (erg 7), phosphomevalonic kinase (erg 8), mevalonic kinase (erg12) and squalene synthetase (erg 9, erg 10, erg 11).

Mutat Res, 1977 Sep, 56(1), 21 - 30
Induction of respiratory deficient mutants in Saccharomyces cerevisiae by mono- and diazido analogs of ethidium; Morita T et al.; Mono- and diazido analogs of ethidium when photolyzed with yeast cells were highly effective in inducing respiratory deficient (RD) mutants . The monoazide was more mutagenic, though slightly less photosensitive, and under the concentrations and conditions used, both required photolysis to be significantly mutagenic . Ethidium bromide (EB) competed with either its mono- or diazide analog for RD induction when applied before, but not after, the photolysis step . This suggested that the initial mutagenic binding sites for azides were identical with those of EB . There was no self-rescue or recovery in azide mutagenesis in contrast to EB . Furthermore, recovery from azide mutagenesis could not be provoked by EB . This confirmed a simple competition between binding of EB and its azide analogs to account for the prevention by EB of the azide induced mutations.

Can J Biochem, 1977 Sep, 55(9), 935 - 41
Purine metabolism in Saccharomyces cerevisiae; Burridge PW et al.; The synthesis, interconversion, and catabolism of purine bases, ribonucleosides, and ribonucleotides in wild-type Saccharomyces cerevisiae were studied by measuring the conversion of radioactive adenine, hypoxanthine, guanine, and glycine into acid-soluble purine bases, ribonucleosides, and ribonucleotides, and into nucleic acid adenine and guanine . The pathway(s) by which adenine is converted to inosinate is (are) uncertain . Guanine is extensively deaminated to xanthine . In addition, some guanine is converted to inosinate and adenine nucleotides . Inosinate formed either from hypoxanthine or de novo is readily converted to adenine and guanine nucleotides.

J Bacteriol, 1977 Sep, 131(3), 735 - 40
Killer double-stranded ribonucleic acid synthesis in cell division cycle mutants of Saccharomyces cerevisiae; Shalitin C et al.; The synthesis of killer double-stranded ribonucleic acid (dsRNA) in Saccharomyces cerevisiae was examined in seven different cell division cycle mutants (cdc) that are defective in nuclear deoxyribonucleic acid replication and contain the "killer character." In cdc28, cdc4, and cdc7, which are defective in the initiation of nuclear deoxyribonucleic acid synthesis, and in cdc23 or in cdc14, defective in medial or late nuclear division, an overproduction of dsRNA at the restrictive temperature was observed . In contrast to the above mutants, the synthesis of killer dsRNA is not enhanced at the restrictive temperature in either cdc8 or cdc21, which are defective in deoxyribonucleic acid chain elongation . Examination of killer sensitive strains (cdc7 K- and cdc4 K-) has shown that the complete killer dsRNA genome is essential for the overproduction of dsRNA at the restrictive temperature.

J Bacteriol, 1977 Sep, 131(3), 1013 - 5
Inhibition of thiamine transport in Saccharomyces cerevisiae by thiamine disulfides; Iwashima A et al.; Both thiamine disulfide and O-benzoyl thiamine disulfide, which are thiolfrom derivatives of thiamine, strongly inhibited thiamine transport in Saccharomyces cerevisiae . The inhibition appeared to be due to a high affinity of the analogs for yeast cell membranes, in which thiamine transport component(s) may be integrated.

Biotechnol Bioeng, 1977 Sep, 19(9), 1363 - 74
Some observations on oscillatory changes in the growth rate of Saccharomyces cerevisiae in aerobic continuous undisturbed culture; Borzani W et al.; Oscillatory changes in the growth rate were observed in undisturbed continuous culture of Saccharomyces cerevisiae on sugar-cane molasses media when nitrogen sources (2.56 to 6.17 g/liter of ammonium sulfate or 1.22 g/liter of urea) were added to the feeding mash and when the air rate was 1.3 to 1.6 v/v/m . The oscillations were not affected by the addition of yeast extract . The suppression of the nitrogen source during the continous test leads to a nonoscillatory transient state . No oscillations occured at all when no nitrogen source was added to the medium and/or the air rate was equal to zero or equal to about 3.3 v/v/m . The oscillatory responses of the system were affected by a previous anaerobic continuous cultivation of the yeast.

Hoppe Seylers Z Physiol Chem, 1977 Sep, 358(9), 1119 - 24
Structure of a cytochrome b-c 1 complex from Saccharomyces cerevisiae YF; Reed J et al.; 1) An isolation and purification procedure is reported for an active cytochrome b-c1 complex from Saccharomyces cerevisiae . The complex acts as an antimycin A-sensitive duroquinone-cytochrome c reductase and contains cytochromes b and c1 at a concentration of 8 nmol/mg protein and non-heme iron at a concentration of 15 nmol/mg protein . 2) Difference spectra at room temperature and at 70 degrees K show that the preparation is free from contamination with cytochromes c or aa3 . Assays of enzyme activity indicate the absence of any of the other catalytic functions normally associated with the mitochondrial respiratory chain . 3) On dissociation and separation on sodium dodecylsulfate-polyacrylamide gels the complex gives rise to seven bands corresponding to subunit polypeptide molecular weights of 43 000, 40 000, 32 000, 24 000, 22 000, 20 000 and 18 000 . These appear in a regular stoichiometry of 1:1:3:1:1:1:1.

J Bacteriol, 1977 Sep, 131(3), 839 - 47
Allantoin transport in Saccharomyces cerevisiae; Sumrada R et al.; Allantoin uptake in both growing and resting cultures of Saccharomyces cerevisiae occurs by a low-Km (ca . 15 micrometer) transport system that uses energy that is likely generated in the cytoplasm . This conclusion was based on the observation that transport did not occur in the absence of glucose or the presence of dinitrophenol, carbonyl cyanide-m-chloro-phenyl hydrazine, fluoride, or arsenate ions . Normal uptake was observed, however, in the presence of cyanide . The rate of accumulation was maximal at pH 5.2 . In contrast to the urea transport system, allantoin uptake appeared to be unidirectional . Preloaded, radioactive allantoin was not lost from cells suspended in allantoin-free buffer and did not exchange with exogenously added, nonradioactive allantoin . Treatment of preloaded cells with nystatin, however, released the accumulated radioactivity . Allantoin accumulated within cells was isolated and shown to be chemically unaltered.

Biochem J, 1977 Aug 15, 166(2), 275 - 85
The manipulation of cellular cytochrome and lipid composition in a haem mutant of Saccharomyces cerevisiae; Astin AM et al.; 1 . The ole-3 mutant of Saccharomyces cerevisiae has an early lesion in the pathway of porphyrin biosynthesis . 2 . This results in the loss of all haem-containing enzymes, including the mitochondrial cytochromes, and prevents the synthesis of components whose formation requires haem-containing enzymes, including unsaturated fatty acids, ergosterol and methionine . 3 . The pleiotropic effects of the primary lesion are reversed by growing mutant ole-3 aerobically in the presence of intermediates of the porphyrin-biosynthetic pathway, and the present work reports the degree of manipulation of lipid and respiratory-cytochrome composition . 4 . Supplements of delta-aminolaevulinate in the range 0.5--500 mg/l result in a progressive increase in the cellular content of unsaturated fatty acids and respiratory cytochromes, cause the replacement of lanosterol and squalene by ergosterol, and an increase in total sterol content . 5 . Haematoporphyrin and protoporphyrin IX have similar but less extensive effects on cellular composition, whereas haematin allows unsaturated fatty acid synthesis and some sterol synthesis, but has no effect on the formation of respiratory cytochromes . 6 . These results suggest that growth of the organism in the presence of defined amounts of delta-aminolaevulinate will be useful in the investigation of the role of lipids and cytochromes in the function and assembly of mitochondrial membranes.

J Cell Sci, 1977 Aug, 26, 373 - 85
The induction of cytoplasmic petite mutants of Saccharomyces cerevisiae by hydrostatic pressure; Rosin MP et al.; This study demonstrates that hydrostatic pressure is a potent inductive agent of the petite mutation in cultures of Saccharomyces cerevisiae . The inductive capacity of this mutagen is dependent on the magnitude and the duration of the pressure treatment . Furthermore, the extent of petite induction varies with the growth stage of the culture . Induction occurs in pressure-treated (1-4 X 1-(4) lbf in.-2 or 9-66 X 10(4) kN m-2 for 4 h) log growth cultures but not in stationary or lag phase cultures . Petite induction and cell survival are also dependent on the particular strain of yeast which is pressure-treated . Tetrad analysis and complementation assays demonstrate that pressure-induced petite cells are cytoplasmic in nature . Moreover, induced petite cells show a wide range of suppressivity (2--99%) with a large proportion of the petite cells being highly suppressive.

Lipids, 1977 Aug, 12(8), 666 - 8
Accumulation of ergosta-8,14-dien-3beta-ol by Saccharomyces cerevisiae cultured with an azasterol antimycotic agent; Hays PR et al.; 15-Aza-25-methylene-D-homocholesta-8,14-dien-3beta-ol, an antimycotic agent, at a concentration of 75 ng/ml inhibited ergosterol biosynthetis in Saccharomyces cerevisiae strain 3701B resulting in the accumulation of an unusual sterol . Experimental data presented indicate that this sterol is ergosta-8,14-dien-3beta-ol . The accumulation of the compound is supportive of current models of biosynthetic pathways for sterols in yeast and is consistent with inhibition by the azasterol of the delta14 sterol reductase.

Lipids, 1977 Aug, 12(8), 645 - 54
Sterol mutants of Saccharomyces cerevisiae: chromatographic analyses; Bard M et al.; The sterols accumulated by ergosterol deficient mutants of the genes erg6, erg2, erg3, and erg5 (formerly po11, po12, po13, and po15) have been analyzed by gas liquid chromatography . Together with pure sterols obtained from the mutants, they were characterized on SE-30, OV-17, and OV-225 . The effects of molecular structure on the retention characteristics of a range of C28 ergostane sterols have been studied . The double mutants obtained by crossing the single mutants were also analyzed and their sterols identified where possible . The effects of the erg mutations on the control of sterol biosynthesis in yeast are discussed.

J Bacteriol, 1977 Aug, 131(2), 638 - 44
Localization of acid phosphatase in Saccharomyces cerevisiae: a clue to cell wall formation; Linnemans WA et al.; Acid phosphatase is present in two layers of the cell envelope of Saccharomyces cerevisiae . These are separated by another layer, which is free of acid phosphatase . We have evidence that the cell wall is built up in two stages, which are independent . In the first stage, the cell wall is built up during the formation of the bud . Glucanase vesicles are involved in this process . In the second stage, a thick layer is deposited at the inside against the new cell wall . This results in the thick, rigid wall of the mature yeast cell . This latter layer is probably assembled on the outer surface of the plasmalemma.

Genetics, 1977 Aug, 86(4), 745 - 64
Frameshifts and frameshift suppressors in Saccharomyces cerevisiae; Culbertson MR et al.; Using ICR-170 as a mutagen, we have induced a set of mutations in yeast which exhibit behavior similar to that shown for bacterial frameshift mutations . Our genetic study shows that these mutations are polar; the polarity can be relieved by internal suppressors; they revert with acridine half-mustards and are not suppressed by known nonsense suppressors . However, they are suppressed by other dominant external suppressors, which fall into two mutually exclusive groups . Five genetically distinct suppressors were obtained for one of these groups, using co-reversion of two frameshift markers . Three of these are lethal in combination with each other and show a reduction in the GLY3 tRNA peak on a Sepharose 4B column . A fourth suppressor shows an altered chromatographic profile for GLY1 tRNA . We suggest that this group of suppressors represent mutations in the structural genes for the isoaccepting glycyl-tRNA's . Two other suppressors (one linked to the centromere of chromosome III) were found to suppress a second group of frameshifts . Genetic and biochemical studies show that the nonMendelian factor (PSI+) increases the efficiency of some frameshift suppressors.

Can J Microbiol, 1977 Aug, 23(8), 1078 - 80
{Immunologic properties of various cell fractions of a wild strain and a mutant strain of Saccharomyces cerevisiae Hansen}; Kolodynski J et al.; Some fractions of the Saccharomyces cerevisiae cell wall have been prepared by the action of Helix pomatia juice on intact cells . Immunosera were obtained by injecting rabbits with these fractions . Immunofluorescence reactions, obtained with these sera, show that some fractions of mannopeptides when extracted from a "smooth-colony" mutant strain, have lost antigenic determinants.

Mol Gen Genet, 1977 Jul 20, 154(2), 199 - 202
Genetic studies of the pyrimidine permeases from Saccharomyces cerevisiae: lack of intragenic complementation; Parlebas N et al.; A search for intragenic complementation of mutants of the cytosine and uracil permeases of Saccharomyces cerevisiae was made . Among numerous diploid pairs of mutants of the cytosine permease gene no complementation was found . Similarly negative results were obtained with pairs of mutants of the uracil permease . The significance of these results is discussed.

Mol Gen Genet, 1977 Jul 20, 154(2), 221 - 3
Endonuclease for apurinic sites in yeast . Comparison of the enzyme activity in the wild type and in rad mutants of Saccharomyces cerevisiae to MNS; Chlebowicz E et al.; It was found that yeast cells contain an endonuclease specific for apurinic sites in DNA which has no effect on DNA with normal strands or on strands with alkylated sites . The enzyme activity was studied in the RAD strain and in rad 6, rad 18-2 and rad 21 mutants, all very sensitive to MMS, as compared to the wild type . The level of endonuclease activity does not differ much between the tested strains, regardless of their differences in susceptibility to MMS . The enzyme activity is not induced by pretreatment of the cells with this mutagen.

Experientia, 1977 Jul 15, 33(7), 870 - 1
Synthetic identification as a hexapeptide of alpha substance-IB inducing sexual agglutination in Saccharomyces cerevisiae; Aoyagi H et al.; For the identification of a peptidyl principle inducing sexual agglutination in the yeast, 2 supposed hexapeptides (1a, b) were synthesized by the conventional method . The 1a (H-Arg-Gly-Pro-Phe-Pro-Ile-OH) revealed complete identity with the natural peptide in TLC, MS and biological property on agglutination . The 1b showed the sexual agglutinability in the same degree as 1a, though distinct differences were observed in the chemical data . Both 1a and 1b had a strong bitter taste.

Mol Gen Genet, 1977 Jul 7, 154(1), 75 - 82
Mutants of Saccharomyces cerevisiae resistant to carbon catabolite repression; Zimmermann FK et al.; Mutants with defective carbon catabolite repression have been isolated in the yeast Saccharomyces cerevisiae using a selective procedure . This was based on the fact that invertase is a glucose repressible cell wall enzyme which slowly hydrolyses raffinose to yield fructose and that the inhibitory effects of 2-deoxyglucose can be counteracted by fructose . Repressed cells were plated on a raffinose--2-doexyglucose medium and the resistant cells growing up into colonies were tested for glucose non-repressible invertase and maltase . The yield of regulatory mutants was very high . All were equally derepressed for invertase and maltase, no mutants were obtained with only non-repressible invertase synthesis which was the selected function . A total of 61 mutants isolated in different strains were allele tested and could be attributed to three genes . They were all recessive . Mutants in one gene had reduced hexokinase activities, the other class, located in a centromere linked gene, had elevated hexokinase levels and was inhibited by maltose . Mutants in a third gene were isolated on a 2-deoxyglucose galactose medium and had normal hexokinase levels . A partial derepression was observed for malate dehydrogenase in all mutants . Isocitrate lyase, however, was still fully repressible.

Mol Gen Genet, 1977 Jul 7, 154(1), 23 - 30
Methionine biosynthesis in Saccharomyces cerevisiae . II . Gene-enzyme relationships in the sulfate assimilation pathway; Masselot M et al.; In Saccharomyces cerevisiae, the products of eleven different genes are needed for a functional sulfate assimilation pathway . Only five enzymatic steps are known in this pathway . The study of the gene-enzyme relationships has shown that the enzymes catalysing two of these steps are probably heteropolymeric . Moreover, mutations in three unlinked genes lead to multiple enzymatic losses . Different hypotheses are made to account for these results.

Proc Natl Acad Sci U S A, 1977 Jul, 74(7), 2850 - 4
Isolation of folded chromosomes from the yeast Saccharomyces cerevisiae; Pinon R et al.; Two fast-sedimenting chromatin complexes with sedimentation velocities of approximately 4600 and 3000 S can be isolated from logarithmically growing diploid Saccaromyces cerevisiae cells . The DNA in both structures appears to be folded into at least 60 domains and characterized by a negative superhelical density . Sensitivity to proteases and insensitivity to RNases suggest that proteins and not RNA are important in maintaining the organization of the chromosomes in both structures . The 46000S and 3000S complexes represent folded genomes isolated from diploid cells in the G2 and G1 stages of the cell cycle, respectively.

Int J Radiat Biol Relat Stud Phys Chem Med, 1977 Jul, 32(1), 33 - 41
Split-dose and liquid-holding recovery after X-irradiation in diploid yeast Saccharomyces cerevisiae . II . Dependence of the recovery process on cellular protein metabolism; Wienhard I et al.; In diploid yeast, split-dose recovery (SDR) after X-irradiation was affected, if incubation between split doses was performed in the presence of the protein-synthesis inhibitor, cycloheximide . In exponentially-growing cell-cultures, early SDR was undisturbed but complete recovery was not achieved . Concomitantly the cells show a decresing ability to perform subsequent liquid-holding recovery (LHR) . In stationary-phase cell-cultures, SDR was completely suppressed . The cells show, however, recovery from potentially lethal damage in the presence of cycloheximide during incubation between the dose-fractions . The experimental results suggest that in diploid yeast SDR after X-irradiation is an enzymatic process dependent on a functioning protein metabolism.

J Bacteriol, 1977 Jul, 131(1), 163 - 73
Molecular events associated with induction of arginase in Saccharomyces cerevisiae; Bossinger J et al.; Arginase, the enzyme responsible for arginine degradation in Saccharomyces cerevisiae, is an inducible protein whose inhibition of ornithine carbamoyl-transferase has been studied extensively . Mutant strains defective in the normal regulation of arginase production have also been isolated . However, in spite of these studies, the macromolecular biosynthetic events involved in production of arginase remain obscure . We have, therefore, studied the requirements of arginase induction . We observed that: (i) 4 min elapsed between the addition of inducer (homoarginine) and the appearance of arginase activity at 30 degrees C; (ii) induction required ribonucleic acid synthesis and a functional rna1 gene product; and (iii) production of arginase-specific synthetic capacity occurred in the absence of protein synthesis but could be expressed only when protein synthesis was not inhibited . Termination of induction by inducer removal, addition of the ribonucleic acid synthesis inhibitor lomofungin, or resuspension of a culture of organisms containing temperature-sensitive rna1 gene products in a medium at 35 degrees C resulted in loss of ability for continued arginase synthesis with half-lives of 5.5, 3.8, and 4.5 min, respectively . These and other recently published data suggest that a variety of inducible or repressible proteins responding rapidly to the environment may be derived from labile synthetic capacities, whereas constitutively produced proteins needed continuously throughout the cell cycle may be derived from synthetic capacities that are significantly more stable.

J Biochem (Tokyo), 1977 Jul, 82(1), 73 - 9
Purification and properties of aldehyde dehydrogenase from Saccharomyces cerevisiae; Tamaki N et al.; A procedure for the purification of aldehyde dehydrogenase from bakers' yeast (Saccharomyces cerevisiae) is reported . Treatment with acid, heat and organic solvents was avoided and chromatographic and filtration techniques in the presence of phenylmethylsulfonylfluoride were mainly used . An affinity chromatography step using the reactive dye Cibacron blue F3G-A, which was covalently bound to Sepharose 4B, was found to be essential . The enzyme was bound to and then released from the dye . The purified enzyme was shown to be homogeneous by gel filtration, disc electrophoresis and SDS electrophoresis . The molecular weight of the purified enzyme determined by gel filtration was 170,000, which agreed with that of the enzyme in the crude extract . The enzyme was composed of subunits of a molecular weight of 57,000 . The specific activity of the enzyme was 20 units per mg of protein under the standard assay conditions . The substrate specificity, the relative maximal velocity, the michaelis constants, the pH optimum, the stability and the activation energy of the enzyme are reported.

J Biol Chem, 1977 Jun 25, 252(12), 4409 - 12
Subunit structure of external invertase from Saccharomyces cerevisiae; Trimble RB et al.; Because 50% of the mass of the external invertase of Saccharomyces cerevisiae consists of carbohydrate, it has been extremely difficult to obtain an accurate molecular weight of this enzyme by centrifugal or electrophoretic techniques . However, on removing almost all of the oligosaccharide chains of this enzyme with the endo-beta-N-acetyl-glucosaminidase H from Streptomyces plicatus, it has been possible to show that carbohydrate-free invertase is composed of two 60,000-dalton subunits . Terminal sequence analysis with carboxypeptidases A, B, and Y provided strong evidence that the subunits are identical.

J Biol Chem, 1977 Jun 10, 252(11), 3599 - 604
Negative interactions between amino acid and methylamine/ammonia transport systems of Saccharomyces cerevisiae; Roon RJ et al.; The transport of methylamine (methylammonium ion) and ammonia (ammonium ion) is accomplished in Saccharomyces cerevisiae by means of a specific active transport system . L-Amino acids are noncompetitive inhibitors of methylamine transport . This inhibition is relieved or eliminated in mutant strains that have a reduced ability to transport amino acids . The inhibition of methylamine transport occurs immediately upon the addition of amino acids to the assay system and persists until the external amino acid pool is depleted . The degree of inhibition observed is a direct function of the rate of amino acid transport . Both methylamine and ammonia are capable of inhibiting amino acid transport . The inhibition of amino acid transport is eliminated in mutant strains that cannot transport methylamine and ammonia.

Mol Gen Genet, 1977 Jun 8, 153(2), 145 - 51
A mutant of Saccharomyces cerevisiae that exhibits multiple isoacceptors for several of its transfer RNAs; Bell JB et al.; A strain of Saccharomyces cerevisiae, known to produce multiple isoaccepting forms of several tRNA's which differ from a standard wild type strain, has been studied genetically . The multiple isoaccepting tRNA phenotype behaves as if it is caused by a single recessive mutation . Five tetrads were analyzed and all showed a 2:2 segregation of mutant to wild type profiles for Phe-tRNA Phe . Furthermore, the multiple isoacceptors for the other tRNA's in the mutant strain are probably caused by the same mutation, since Tyr-tRNA Tyr and Val-tRNA Val also exhibit 2:2 segregation for mutant versus wild type tRNA profiles and the segregation pattern is the same as that for Phe-tRNA Phe.

Biochem J, 1977 Jun 1, 163(3), 521 - 9
Activation of selenate by adenosine 5'-triphosphate sulphurylase from Saccharomyces cerevisiae; Dilworth GL et al.; In the presence of ATP and Mg2+, ATP sulphurylase from Saccharomyces cerevisiae catalysed the conversion of selenate into a compound with the electrophoretic and acid-lability properties of adenosine 5'-sulphatophosphate . Structural characterization, involving extensive purification of adenosine 5'-selenophosphate, proved impossible . However, we showed ATP-, Mg2+- and ATP sulphurylase-dependent, and inorganic pyrophosphatase-stimulated, production of elemental selenium from selenate in the presence of GSH (reduced glutathione) . Since selenate was not reduced by GSH, this reaction proved that ATP sulphurylase had formed an active selenate . The enzyme catalysed formation of elemental selenium had the same kinetics and GSH-dependency as the non-enzymic reduction of selenite to elemental selenium by GSH . In the presence of inorganic pyrophosphatase, 2 mol of Pi was released for each mol of 'active selenate' formed . This was shown by a spectrophotometric assay for elemental selenium . The observed reactivity with thiols and the instability of the enzymic product were those predicted for selenium anhydrides . By analogy with the chemistry of sulphur, the product of the thiolytic cleavage of a selenium anhydride would be converted into selenite . The selenite would then be reduced by the thiol to elemental selenium . We conclude that ATP sulphurylase can catalyse the formation of adenosine 5'-selenophosphate . The anhydride can be reduced by thiols in a manner similar to the reduction of selenite . These results probably explain the ability of mammals, lacking a sulphate reductase system, to incorporate selenium from selenate into seleno-amino acids.

J Bacteriol, 1977 Jun, 130(3), 1310 - 6
Effects of the hypocholesteremic agent trifluperidol on the sterol, steryl ester, and fatty acid metabolism of Saccharomyces cerevisiae; Sobus MT et al.; Trifluperidol (TFP), at a concentration of 100 muM, inhibited the 24-h growth of Saccharomyces cerevisiae by about 30% . Effects on lipid metabolism were investigated by monitoring the incorporation of {1-14C}sodium acetate into various lipid fractions after 4 and 24 h of growth in the presence of several concentrations of TFP . Although little effect was noted on the amount of free sterols, 24-h incorporation of label into steryl esters was increased two- to fourfold by 100 muM TFP . Major sterol components of the steryl ester fraction isolated from an untreated culture were zymosterol (48%) and ergosterol (24%), whereas from the TFP-treated culture delta8,24(28)-ergostadienol (66.6%) and delta8-ergostenol (14.7%) were most abundant . Free sterols present in the highest concentration in the untreated culture were ergosterol (78.2%) and lanosterol (13%); whereas delta8,22-ergostadienol (38.5%), delta8-ergostenol (35.4%), and delta8,24(28)-ergostadienol (25.4%) were the most abundant free sterols obtained from the TFP-treated culture . Thus, the major block in the sterol biosynthetic pathway in yeast appears to be delta8 leads to delta7 isomerization . In these same cultures the relative amounts of C12 and C14 acids isolated from both steryl ester and miscellaneous lipid fractions were increased more than threefold over controls.

J Bacteriol, 1977 Jun, 130(3), 1253 - 61
Evidence that specific and "general" control of ornithine carbamoyltransferase production occurs at the level of transcription in Saccharomyces cerevisiae; Messenguy F et al.; Ornithine carbamoyltransferase synthesis is subject to two major regulatory systems in Saccharomyces cerevisiae . One system is specific for the arginine biosynthetic enzymes, whereas the other appears to be general, acting on a variety of other amino acid pathways as well . We observed that the synthetic capacity for continued ornithine carbamoyltransferase synthesis had the same short half-life (ca . 5 to 7 min) whether repression of enzyme production was brought about by action of the specific or general control system . We present evidence suggesting that both control systems regulate accumulation or ornithine carbamoyltransferase-specific synthetic capacity, rather than modulating its expression.

Can J Microbiol, 1977 Jun, 23(6), 659 - 71
Inhibiton by sulfanilamide of sporulation in Saccharomyces cerevisiae; Colonna WJ et al.; The antimetabolite sulfanilamide inhibits sporulation in Saccharomyces cerevisiae strain AP1 . Cells exposed to sulfanilamide at various times during the sporulation process become progressively insensitive to the drug, although accumulation of sulfanilamide by the cells increases with time . Vegetative growth of AP1 is practically unaffected by sulfanilamide; pregrowth of the cells in the presence of the drug does not prevent sporulation . Thus, inhibition is confined to the meiotic phase of the cell cycle . Sensitivity to sulfanilamide is independent of pH . Increasing the time cells are exposed to sulfanilamide results in a progressive reduction of ascus formation; however, the inhibition is reversible since sporulation can occur in cells exposed to the drug for greater than 24 h . The drug arrests the cells at a point before commitment to sporulation, since yeast cells exposed to sulfanilamide for 12 h do not complete the sporulation process when returnedto vegetative medium, but resume mitotic growth instead . Meiotic nuclear division is largely prevented by sulfanilamide, and synthesis of RNA and protein is severely retarded . DNA synthesis is inhibited up to 50%; glycogen synthesis is approximately 90% inhibited . Other yeast strains showed varying sensitivity to sulfanilamide; homothallic strains were generally less affected.

Eur J Biochem, 1977 May 16, 75(2), 571 - 81
L-Ornithine carbamoyltransferase from Saccharomyces cerevisiae: steady-state kinetic analysis; Simon JP et al.; Ornithine carbamoyltransferase of Saccharomyces cerevisiae is subjected to an enzymatic regulation of its anabolic activity when it is bound to the inducible catabolic arginase as described earlier . This regulatory ornithine carbamoyltransferase essentially catalyzes the synthesis of citrulline, but the reverse reaction could be demonstrated using arsenate instead of phosphate . Steady-state initial velocity studies of the reverse reaction indicate that the mechanism is consistent with a rapid-equilibrium random model (in which all steps are in equilibrium, except that concerned with the interconversion of the central ternary complexes) involving the formation of enzyme - ornithine - arsenate and enzyme - citrulline - phosphate dead-end complexes . In the forward direction, although the mechanism also appears to be random, the results are in better agreement with a preferred ordered binding of substrates, with carbamoylphosphate adding first . This degenerate form of the random mechanism is discussed.

Eur J Biochem, 1977 May 16, 75(2), 619 - 25
Proteolysis of L-(+)-lactate cytochrome c oxidoreductase (cytochrome b2) extracted from Saccharomyces cerevisiae and Hansenula anomala yeasts; Prats M; The L-(+)-Lactate:cytochrome c oxidoreductase or cytochrome b2 from the yeasts Saccharomyces cerevisiae and Hansenula anomala were partially hydrolysed in various concentrations of trypsin . Conditions were found which allowed the isolation from the Hansenula enzyme of a 140 000 +/- 10 000-dalton flavoprotein . The prosthetic flavin groups were still reducible by substrate (spectroscopic evidence) but the flavoprotein was unable to form a complex with cytochrome c, the physiological acceptor in the enzymatic reaction . No such flavoprotein units could be found during proteolysis of the Saccharomyces enzyme . The heme prosthetic group of the Hansenula enzyme remained bound to a 15 500 +/- 1000-dalton protein unit which was larger than, but very similar to, the well known 'cytochrome b2 core' of the Saccharomyces enzyme . Moreover, the degradation of different enzyme samples by contaminated proteases allowed the isolation of a particular form of Hansenula enzyme: each tetramer had, on the mean, four bound flavins and only two heme groups . These molecules completely retained their ability to form a complex with cytochrome c.

J Bacteriol, 1977 May, 130(2), 766 - 74
Recovery of Saccharomyces cerevisiae mating-type a cells from G1 arrest by alpha factor; Chan RK; Mating-type a cells of the yeast Saccharomyces cerevisiae that had been specifically arrested in the G1 phase of the cell cycle by alpha factor, an oligopeptide pheromone made by alpha cells, recovered and resumed cell division after a period of inhibition which was dependent on the concentration of alpha factor used . These treated a cells were more resistant to alpha factor than untreated a cells, but lost their resistance upon further cell division . However, cells arrested for 6 h were no more resistant to alpha factor than cells arrested for only 2.5 h . Mating-type a strains could inactivate or remove alpha factor from the culture fluid, but two a sterile (nonmating) mutants and an a/alpha diploid strain could not . These results suggest that a cells have a mechanism, which may involve uptake or inactivation of alpha factor, for recovering from alpha factor arrest . However, the results do not distinguish between a recovery mechanism which is constitutive and one which is induced by alpha factor . The loss of alpha factor activity during recovery appeared to be primarily cell contact mediated, although an extracellular, diffusible inhibitor of alpha factor that is labile or that functions stoichiometrically could not be ruled out.

J Bacteriol, 1977 May, 130(2), 746 - 9
Isolation and characterization of Saccharomyces cerevisiae glycolytic pathway mutants; Lam KB et al.; Yeast strains carrying recessive mutations representing four different loci that cause defects in pyruvate kinase, pyruvate decarboxylase, 3-phosphoglycerate kinase, and 3-phosphoglycerate mutase were isolated and partially characterized . Cells carrying these mutations were unable to use glucose as a carbon source as measured in turbidimetric growth experiments . Tetrad analysis indicated that these mutations were not linked to each other; one of the mutations, that affecting phosphoglycerate kinase, was located on chromosome III.

J Bacteriol, 1977 May, 130(2), 714 - 23
Amino acid transport and metabolism in nitrogen-starved cells of Saccharomyces cerevisiae; Woodward JR et al.; Nitrogen-starved yeast derepress a general amino acid permease which transports basic and hydrophobic amino acids . Although both groups of amino acids are metabolized, the derivatives of the basic amino acids are retained by the cells, whereas those of the hydrophobic amino acids are released as acidic and neutral deaminated derivatives . The release of the deaminated derivatives of the hydrophobic amino acids only occurs in the presence of glucose, which presumably produces amino acceptors . The accumulation of intracellular amino acids results in trans-inhibition of the uptake of exogenous amino acids whether the intracellular amino acid is a basic amino acid or the product of intracellular transamination from a hydrophobic amino acid . Variation of permease and transaminase activity was measured during growth under repressed (ammonia-grown) and derepressed (proline-grown) conditions . Maximum levels for both activities occurs at the mid-exponential phase.

Genetics, 1977 May, 86(1), 85 - 102
Mutants of formyltetrahydrofolate interconversion pathway of Saccharomyces cerevisiae; McKenzie KQ et al.; Thirteen mutants of Saccharomyces cerevisiae that lack one or more of the three enzyme activities of the pathway for interconversion of tetrahydrofolate coenzymes at the formate level of oxidation have been isolated . They do not require adenine . All fail to complement mutations in the ade3 locus . Mutations that greatly reduce activity for the other two interconversion enzymes . The three enzyme activities cochromatograph on TEAE-cellulose columns . A mutation that eliminates synthetase activity also alters the chromatographic behavior of the remaining cyclohydrolase and dehydrogenase activities . It is suggested that the three activities reside in an enzyme complex encoded by the ade3 locus.

Int J Radiat Biol Relat Stud Phys Chem Med, 1977 May, 31(5), 477 - 84
Split-dose and liquid-holding recovery after X-irradiation on diploid yeast Saccharomyces cerevisiae . I . Dependence on growth-phase; Wienhard I et al.; Liquid-holding recovery (LHR) and the sparing effect of dose fractionation were investigated with 100 kVp-X-rays in diploid yeast from exponential and stationary phase . Exponential cells showed prompt and complete split-dose recovery . The ability to undergo LHR remained constant during 2-5 hours incubation after the first dose . Stationary-phase cells did not exhibit split-dose recovery (SDR) in a simple way: there was an increase in sensitivity after 3-5 hours followed by a gradual increases with time . It is suggested that stationary cells are starved of an essential co-factor which has to be synthesized de nova.

Genetics, 1977 May, 86(1), 33 - 55
Isolation and characterization of MMS-sensitive mutants of Saccharomyces cerevisiae; Prakash L et al.; We have isolated mutants sensitive to methyl methanesulfonate (MMS) in Saccharomyces cerevisiae . Alleles of rad1, rad4, rad52, rad55 and rad57 were found amoung these mms mutants . Twenty-nine of the mms mutants which complement the existing radiation-sensitive (rad and rev) mutants belong to 22 new complementation groups . Mutants from five complementation groups are sensitive only to MMS . Mutants of 11 complementation groups are sensitive to UV or X rays in addition to MMS, mutants of six complementation groups are sensitive to all three agents . The cross-sensitivities of these mms mutants to UV and X rays are discussed in terms of their possible involvement in DNA repair . Sporulation is reduced or absent in homozygous diploids of mms mutants from nine complementation groups.

Mol Gen Genet, 1977 Apr 29, 152(3), 307 - 9
Mapping of mutation tsm-8 with respect to transfer RNA genes on the mitochondrial DNA of Saccharomyces cerevisiae; Monnerot M et al.; A precise localization of the tsm-8 mutation in relation to the transfer RNA genes has been attempted by rho- deletion analysis . The data show that the tsm-8 mutation is in close proximity to the isoleucyl transfer RNA gene . However, it is not yet possible to decide whether the tsm-8 mutation is within this transfer RNA gene.

Mol Gen Genet, 1977 Apr 29, 152(3), 137 - 44
Interaction of super-repressible and dominant constitutive mutations for the synthesis of galactose pathway enzymes in Saccharomyces cerevisiae; Nogi Y et al.; Two dominant uninducible mutant alleles in the gal80 locus were identified . The GAL80s-1 and GAL80s-2 mutants showed novel phenotypes in response to the newly isolated GAL81-1 mutant allele, a dominant constitutive mutation linked to the gal4 locus; the GAL80s-1 GAL81-1 strain was inducible and the GAL80s-2 GAL81-1 strain was uninducible . Many galactose positive revertants from the GAL80s-2 GAL81-1 strain were isolated . It was proved that each revertant was due to a secondary mutation either in the gal80 or GAL81 locus, whereas revertants due to mutation at the supposed controlling site for the structural gene cluster of the galactose-pathway enzymes have not been isolated.

Mol Gen Genet, 1977 Apr 29, 152(3), 125 - 8
Defective thymine dimer excision in radiation-sensitive mutants rad10 and rad16 of Saccharomyces cerevisiae; Prakash L; Two rad mutants of yeast, rad10 and rad16, are shown to be defective in the removal of UV-induced pyrimidine dimers since DNAs obtained from irradiated cells following a post-irradiation incubation in the dark still retain UV-endonuclease-sensitive sites . Both rad10 and rad16 mutants are in the same pathway of excision-repair as the rad1, rad2, rad3 and rad4 mutants.

J Biol Chem, 1977 Apr 25, 252(8), 2560 - 5
Isolation and characterization of valine transfer RNA from Saccharomyces cerevisiae; Aoyagi S et al.; Two procedures for isolating valine tRNA from commercial bakers' yeast were investigated . The first involved: (a) counter double current distribution; (b) chromatography on benzoyl-DEAE-cellulose; (c) reverse phase chromatography on Chromosorb G saturated with trioctylpropylammonium bromide (Oakridge System 3) . The material isolated lacked the 3'-terminal adenylic acid residue . The second procedure involved the first two steps above followed by: (a) enzymatic aminoacylation with a partially purified yeast extract; (b) derivatization with N-phenoxyacetoxysuccinimide; (c) chromatography on benzoyl-DEAE-cellulose; (d) reverse phase chromatography, System 3 . The product was intact tRNA . It was a mixture of isoacceptors (59:41) differing by a modification (uracil leads to dihydrouracil) at position 48 . It was free of denatured material; specific activity 1,825 pmol of valine/A260 unit of tRNA . Sequence analysis confirmed the recently corrected structure (Bonnet, J., Ebel, J . P., Dirheimer, G., Shershneva, L . P., Krutilina, A . I., Venkstern, T . V., and Bayev, A . A . (1974) Biochimie 56, 1211-1213) . A preliminary study of the alkaline hydrolysis of the 7-methylguanosine residue that occurs at position 47 showed that at least two products are formed instead of only one as usually quoted in the literature . A rapid, ultramicro, chromatographic system for separating these products and measuring them quantitatively is described.

Biochim Biophys Acta, 1977 Apr 19, 475(4), 638 - 51
Invertase messenger ribonucleic acid in Saccharomyces cerevisiae . Kinetics of formation and decay; Elorza MV et al.; Saccharomyces cerevisiae -136ts (Hutchison, H.T., Hartwell, L.H . and McLaughlin, C.S . (1969) J . Bacteriol . 99, 807-814) incubated in the presence of maltose at 23 degrees C (permissive temperature) synthesized the RNA messengers which codify derepressed invertase (an external mannoprotein) and induced alpha-glucosidase (a non-glycosylated internal enzyme) . The enzymes were not synthesized if the mutant was transferred to the maltose-containing medium at the moment of incubation at 37 degrees C indicating that the cells had no pools of the specific RNA messengers and that transcription of the DNA was a prerequisite to enzyme synthesis . Cycloheximide inhibited syntheses of the enzymes both at 37 and at 23 degrees C suggesting that the enzymic activities were the result of "de novo" synthesis of the proteins and did not result from the activation of proenzymes . In derepressed cells the number of invertase mRNA molecules is probably larger than that actually being translated . The half-life of the derepressed invertase mRNA was calculated from the moment that the molecules of RNA messenger were limiting the enzyme synthesis and a value of 30-35 min was estimated . The value found for the basal (repression independent) invertase mRNA was of 45-50 min . The half-life of alpha-glucosidase mRNA was computed following the mathematical procedure described in the Appendix, and a value of 23 min was obtained . These results are consistent with the existence of relatively long-lived RNA messengers involved in the synthesis of extracellular macromolecules.

Can J Microbiol, 1977 Apr, 23(4), 407 - 12
Amino acid uptake and protein synthesis in germinating spores of Saccharomyces cerevisiae; Steele SD et al.; Spores transferred to germination medium incorporated exogenous lysine into protein within 20 min but required 2-3 to begin incorporation of exogenous proline or alanine . During this time considerable uptake of amino acids into the intracellular pool occurred . Cycloheximide added to the germination medium inhibited incorporation of lysine into protein but did not lessen in accumulation in the pool . Spore germination was inhibited by cycloheximide.

J Bacteriol, 1977 Apr, 130(1), 128 - 30
Genetic and physiological relationships between L-asparaginase I and asparaginase II in Saccharomyces cerevisiae; Jones GE; The cistron that codes for L-asparaginase I in Saccharomyces cerevisiae (aspl) is not genetically linked to either of the cistrons coding for expression of asparaginase II (asp2 and asp3) . Cells containing different combinations of theses enzymes grow at different rates in media in which L-asparagine or D-asparagine is the only source of nitrogen for cell replication . Cells lacking L-asparaginase I but possessing asparaginase II grow more rapidly in medium containing D-asparagine as a nitrogen source than cells containing both enzymes, even though D-asparagine is not a substrate of L-asparaginase I . These results indicate that L-asparaginase I and asparaginase II interact in some way to regulate the utilization of asparagine as a nitrogen source for cell growth.

Mutat Res, 1977 Apr, 48(2), 173 - 80
Mutagenic and lethal effects of alpha-benzene hexachloride, dibutyl phthalate and trichloroethylene in Saccharomyces cerevisiae; Shahin MM et al.; Saccharomyces cerevisiae strain XV185-14C for reversion studies was used to investigate the genetic activity of alpha-benzene hexachloride dibutyl phthalate and trichloroethylene . The results indicate that none of the three compounds was genetically active when yeast cells were treated in phosphate buffer (pH 7.0) in the absence of metabolic conversion . However, in the presence of the 9000 g supernatant of mice liver homogenate, NADP, glucose-6-phosphate, phosphate buffer (PH 7.4), MgCl2, KCl, the components which were used for the metabolic conversion, trichloroethylene porved to be a powerful mutagen . It increases the frequency of homoserine, histidine and lysine revertants over those of the control levels . Trichloroethylene appears to induce frameshift as well as base substitution mutations.

Mol Gen Genet, 1977 Mar 28, 152(1), 13 - 8
Single gene alteration of plasma and mitochondrial membrane function in Saccharomyces cerevisiae; Rank GH et al.; Some physiological properties of a multiple-drug-resistant mutant with a permeability barrier to chloramphenicol and its isogenic parental strain were compared . The ATPase specific activity of plasma and mitochondrial membranes isolated from the mutant strain was approximately 20% lower (P less than 0.001, Tables 1 and 2) than that of membranes isolated from the isogenic parental strain . Additional evidence of altered mitochondrial function was: (i) the enhanced growth of the parental strain was eliminted by the {rho-} state (Table 3); (ii) the mutant strain had a greater resistance to petite induction by ethidium bromide (Table 4); (iii) the mutant strain was unable to use a nonfermentable energy source for respiratory adaptation (Table 5) . It is proposed that a single gene mutation has resulted in an alteration of some physiological properties of the plasma and mitochondrial membranes.

Philos Trans R Soc Lond B Biol Sci, 1977 Mar 21, 277(955), 351 - 8
Meiosis in a temperature-sensitive DNA-synthesis mutant and in an apomictic yeast strain (Saccharomyces cerevisiae); Moens PB et al.; It is shown that in the temperature-sensitive yeast mutant (Saccharomyces cerevisiae) spo 11 at the restrictive temperature of 34 degrees C . (1) premeiotic DNA synthesis is nearly completely blocked; (2) the nucleus enters meiotic prophase indicated by the formation of axial cores and polysynaptonemal complexes; (3) the kinetic apparatus functions normally at meiosis I and II; (4) early spore formation occurs in nearly all cells but it is variable and all spores eventually degenerate . It is concluded that chromosome replication is not a prerequisite for the functions listed above . The apomictic yeast strain 4117 produces 2 diploid spores . It is shown that a diploid which produces 2-spored asci, synthesized from 4117, no . 5, and an adenine requiring strain (1) has a normal meiotic prophase with abundant synaptonemal complexes; (2) has only one meiotic spindle; (3) has spores which form red clones more frequently than normal or u.v.-treated vegetative cells form ade/ade red sectors through mitotic recombination . It is concluded that this apomictic yeast has maintained meiotic prophase, but that one of the two meiotic divisions is suppressed.

Mol Gen Genet, 1977 Mar 16, 151(3), 229 - 44
Construction and restriction endonuclease mapping of hybrid plasmids containing Saccharomyces cerevisiae ribosomal DNA; Cramer JH et al.; Fragments produced by partial digestion of Saccharomyces cerevisiae ribosomal DNA (rDNA) with the restriction endonuclease EcoRI were ligated in vitro to the bacterial plasmid RSF2124 . The resulting hybrid plasmids were cloned in Escherichia coli . Three hybrid plasmids which contain at least one intact repetitive unit of the multiple, tandem sequences of the yeast rDNA genes have been further characterized . These plasmids have been used to construct a map of the EcoRI, SmaI, HindII and HindIII restriction sites in the individual repetitive units of yeast rDNA.

Mol Gen Genet, 1977 Mar 7, 151(2), 127 - 36
Biogenesis of mitochondria 48: mikamycin resistance in Saccharomyces cerevisiae--a mitochondrial mutation conferring resistance to an antimycin A-like contaminant in mikamycin; Obbink DJ et al.; Commercial preparations of mikamycin have been shown to act as both inhibitors of mitochondrial protein synthesis and respiration . These preparations are shown to consist of two major streptogramin components (mikamycin A and mikamycin B) and a number of minor components . The major streptogramin components which inhibit mitochondrial protein synthesis in vitro are without effect in vivo due to whole cell impermeability to these compounds . A minor antimycin A-like component is the active compound in mikamycin preparations which inhibits growth of yeast cells on ethanol . The site of this inhibition is at the level of respiratory Comples III . The mitochondrial {mik 1-r} mutation confers resistance to this minor growth inhibitory component and cross resistance to antimycin A . For clarity the designation mik 1 has therefore been renamed ana 1 to denote the mitochondrial determinant conferring resistance to antimycin A . Genetic and physical mapping studies localise the ana 1 determinant in the region of mitochondrial DNA specifying cytochrome b . It is proposed that the ana 1 locus is part of a gene specifying a membrane component of Complex III.

Biochim Biophys Acta, 1977 Mar 2, 475(1), 64 - 73
Increased synthesis of abundant poly(A)-containing RNA in a DNA defective mutant of Saccharomyces cerevisiae containing the "killer character"; Fischer I et al.; A Saccharomyces cerevisiae strain which contains both the "killer character" and a ts mutation in the initiation of nuclear DNA synthesis (cdc4) was studied . Incubation of this strain at the restrictive temperature caused a 3--4 fold increase in the relative rate of synthesis of abundant RNA which contains poly(A) and a 2--3-fold increase in the relative rate of synthesis of killer dsRNA . Thus, the amount of killer dsRNA found in these cells seems to be correlated to the amount of abundant poly(A)-RNA.

Biochim Biophys Acta, 1977 Mar 2, 475(1), 103 - 12
The mechanism of catabolite inhibition of invertase by glucose in Saccharomyces cerevisiae; Elorza MV et al.; Saccharomyces cerevisiae -136ts synthesized invertase in media containing maltose and sucrose . In the presence of glucose synthesis of enzyme took place when the sugar concentration was lower than 1% . At higher concentrations enzyme formation was repressed . Analysis of the glucose effect before RNA inhibition showed that the hexose interfered with the transcription of DNA into invertase messenger RNA . Translation of invertase messenger already formed was also inhibited and the kinetics of this effect was similar to that produced by cycloheximide . Invertase activity was independent of glucose suggesting that the hexose produces no catabolite inhibition of invertase activity . Inhibition of invertase translation by glucose turned out to be reversible but the amount of enzyme produced was dependent on duration of treatment . It is suggested that the catabolite repression of invertase synthesis produced by glucose operates at the levels of transcription and translation and produces an increase in the rate of mRNA degradation . The catabolite repression has no effect on secretion and does not interfere with the catalytic activity of invertase.

Proc Natl Acad Sci U S A, 1977 Mar, 74(3), 1177 - 80
Magnification of genes coding for ribosomal RNA in Saccharomyces cerevisiae; Kaback DB et al.; When a strain of Saccharomyces cerevisiae monosomic for chromosome I and initially deficient for 25% of the genes coding for ribosomal RNA is repeatedly subcultured, the number of these genes increases to and remains stable at the number in the wild type . This strain shows 2:2; viable: inviable first division segregation and hemizygosity for the ade1 gene (a chromosome I marker), evidence that the strain is still monosomic for chromosome I . The increase in the number of genes coding for ribosomal RNA in yeast may be analogous to the magnification of the ribosomal RNA genes in Drosophila melanogaster bobbed mutants.

J Bacteriol, 1977 Mar, 129(3), 1428 - 34
Expression of cryptopleurine resistance in Saccharomyces cerevisiae; Meade JH et al.; An examination of gene expression in diploids may not always be sufficient for determination of the dominant or recessive character of an allele . In Saccharomyces cerevisiae resistance to cryptopleurine has been attributed to a single recessive nuclear gene, cryl, located on chromosome III . We found, contrary to expectations, that resistance to cryptopleurine is not expressed in diploids that are monosomic for chromosome III . Examination of strains of different ploidy on gradient plates shows that the presence of the sensitive allele in a cell does not affect the level of resistance, but rather the level of resistance is directly related to the ratio of resistant alleles to the number of chromosome sets.

J Bacteriol, 1977 Mar, 129(3), 1343 - 8
Two-carbon assimilative capacity and the induction of isocitrate lyase in Saccharomyces cerevisiae; Gonzalez E; The yeast Saccharomyces cerevisiae was grown on 10% glucose medium and subsequently transferred to fresh medium containing 2- and 3-carbon substrates . Under these conditions, the yeast rapidly acquired an oxidative capacity, as evidenced by oxygen uptake rates and 14CO2 evolution rates during respiration on ethanol or (14C)acetate . The assimilative capacity for 2-carbon substrates developed more slowly and followed the induction of isocitrate lyase . Washed yeast transferred to the basic medium containing no added carbon substrate possessed only low levels of isocitrate lyase after a 6-h adaptation . After 6 h, isocitrate lyase was present at high levels in cells transferred to a range of ethanol concentrations but was present in only low amounts in cells transferred to acetate . The role of ethanol as an inducer of isocitrate lyase is discussed.

J Bacteriol, 1977 Mar, 129(3), 1335 - 42
Isolation and characterization of Saccharomyces cerevisiae mutants defective in glycerol catabolism; Sprague GF et al.; Mutants of the yeast Saccharomyces cerevisiae that are defective in the catabolism of glycerol were isolated, and two types of mutants were obtained . One type was deficient in glycerol kinase activity, whereas the other type was deficient in sn-glycerol 3-phosphate dehydrogenase activity . Genetic analysis indicated that each mutant strain owed its phenotype to a single nuclear mutation, and that the two mutations were complementary . The mutations were not linked to each other or to any of 10 loci tested . In addition, neither mutation was centromere linked . Possible mechanisms for the regulation of these enzymes were tested by growing the parental strain in the presence of various carbon sources.

J Bacteriol, 1977 Mar, 129(3), 1375 - 8
Sterol 24(28) methylene reductase in Saccharomyces cerevisiae; Neal WD et al.; Optimal conditions for the 24(28)methylene reductase were obtained . The enzyme assay provided for unusually high activity; the Km was determined to be 10.8 mum . The enzyme activity was increased in cells grown with ethanol as the substrate.

Mol Gen Genet, 1977 Feb 15, 150(3), 271 - 84
Saccharomyces cerevisiae 2-mum DNA . An analysis of the monomer and its multimers by electron microscopy; Royer HD et al.; The non-tandem inverted duplication in the 2-mum DNA of Saccharomyces cerevisiae has a length of 0.19 mum and is located asymmetrically along the molecule . The majority of the dumb-bell structures that are formed upon denaturation and self-annealing of the 2-mum monomer consists of the renatured inverted duplication sequences as double stranded stem and two single stranded loops of 0.67mum+/-0.06 mum (S-loop) and 0.86 mum+/-0.05 mum (L-loop) length . Two additional size classes which comprised 5-10% of the measured molecules had contour lengths of around 1.7 mum and 2.1 mum . The smaller dumb-bells contained two S-loops and the larger dumb-bells contained two L-loops as was shown by heteroduplex mapping with an HindIII fragment from the L-loop . Two models which assume illegitimate or site specific recombination, are presented to explain the generation of double S-loop and double L-loop molecules . At least part of the 4-mum and 6-mum circular molecules present in the yeast supercoiled DNA fraction are shown to be dimers and trimers of 2-mum monomers, but often with inverted loop segments most probably due to intramolecular recombination between sequences of the inverted duplication.

Biochim Biophys Acta, 1977 Feb 14, 465(1), 138 - 51
Ureidosuccinic acid permeation in Saccharomyces cerevisiae; Greth ML et al.; Some strains of Saccharomyces cerevisiae exhibit a specific transport system for ureidosuccinic acid, which is regulated by nitrogen metabolism . Ureidosuccinic acid uptake occurs with proline but with ammonium sulfate as nitrogen source it is inhibited . The V for transport is 20-25 mumol/ml cell water per min . The apparent Km is 3-10(-5) M . For the urep1 mutant (ureidosuccinic acid permease less) the internal concentration never exceeds the external one . In the permease plus strain ureidosuccinic acid can be concentrated up to 10 000 fold and the accumulated compound remains unchanged in the cells . Energy poisons such as dinitrophenol, carbonyl cyanide-m-chlorophenyldrazone (CCCP) or NaN3 inhibit the uptake . No significant efflux of the accumulated compound occurs even in the presence of these drugs . The specificity of the permease is very strict, only amino acids carrying an alpha-N-carbamyl group are strongly competitive inhibitors . The high concentration capacity of the cells and lack of active exit of the accumulated compound support the hypothesis of a carrier mediated active transport system.

Mol Cell Biochem, 1977 Feb 4, 14(1-3), 19 - 24
Determinant for multiple drug resistance possessing features of a mitochondrial episome in Saccharomyces cerevisiae; Nevzglyadova OV et al.; A mutation for multiple resistance to tetracycline, cycloheximide and oligomycin appears to be followed by reconstruction of the mitochondrial genome resulting in the formation of independent nucleotide sequences that determine different resistant phenotypes . Heterozygotes for the cross resistance factor lack locus T responsible for relation tetracycline which comes from the alpha-parent . The nuclear recessive gene-suppresor i induces deletion of the whole determinant for multiple resistance . The loss of mt-DNA on ethidium bromide treatment does not lead to the loss of this determinant which remains in the cells either in an active or in a passive state.

Genetics, 1977 Feb, 85(2), 209 - 23
Bipartite structure of the ade3 locus of Saccharomyces cerevisiae; Jones EW; Forty ade3 mutants were examined with respect to their growth requirements, levels of the tetrahydrofolate interconversion enzymes, and/or map positions . Four deletions were detected . Mutations that result in a requirement for adenine and histidine map in one region of the locus; those which result in a requirement for adenine only map in a quite separate region of the locus, a region not disclosed in previous studies . No correlation was observed between growth properties of the strains and enzyme levels.

Mutat Res, 1977 Feb, 42(2), 223 - 34
Molecular specificity of x-radiation and its repair in Saccharomyces cerevisiae; Magni GE et al.; Molecular specificity of soft X-radiation has been studied in yeast by analyzing the transitions UAA in equilibrium UAG and nonsense leads to sense mutations in the codon tyr7-1 . Synchronized cell populations in the most radiosensitive and radioresistant stages were compared: they did not show any qualitative or quantitative differences in their sensitivities to the mutagenic action of X-rays . We conclude that repair mechanisms, which remain unexpressed in the sensitive cells, do not affect point mutations of the base-substitution type.

J Bacteriol, 1977 Feb, 129(2), 926 - 33
"Active" one-carbon generation in Saccharomyces cerevisiae; Ogur M et al.; A new mutation introducing a one-carbon requirement (e.g., formate) for the glycine-supplemented growth of a serine-glycine auxotroph (ser1) was correlated with a lack of glycine decarboxylase activity . The presence of oxalate decarboxylase activity or glyoxylate decarboxylase activity did not overcome the one-carbon requirement . Another mutation characterized by the absence of oxalate decarboxylase activity did not introduce a one-carbon requirement . The presence and physiological significance of glycine decarboxylase activity in Saccharomyces are thus inferred.

J Bacteriol, 1977 Feb, 129(2), 668 - 77
Mode of action of yeast toxins: energy requirement for Saccharomyces cerevisiae killer toxin; Skipper N et al.; The role of the energy status of the yeast cell in the sensitivity of cultures to two yeast toxins was examined by using 12K release from cells as a measure of toxin action . The Saccharomyces cerevisiae killer toxin bound to sensitive cells in the presence of drugs that interfered with the generation or use of energy, but it was unable to efflux 12K from the cells under these conditions . In direct contrast, the Torulopsis glabrata pool efflux-stimulating toxin induced efflux of the yeast 42K pool was insensitive to the presence of energy poisons in cultures . The results indicate that an energized state, maintained at the expense of adenosine 5'-triphosphate from either glycolytic or mitochondrial reactions, is required for the action of the killer toxin on the yeast cell.

J Bacteriol, 1977 Feb, 129(2), 1144 - 7
Stability of the plasma membrane in Saccharomyces cerevisiae enriched with phosphatidylcholine or phosphatidylethanolamine; Hossack JA et al.; Spheroplasts from Saccharomyces cerevisiae NCYC 366, enriched in phosphatidylethanolamine after growth in medium supplemented with 1 mM ethanolamine, were more resistant to osmotic lysis than were spheroplasts from cells grown in the presence of 1 mM choline and enriched in phosphatidylcholine.

J Bacteriol, 1977 Feb, 129(2), 1066 - 71
Volume-related mitochondrial deoxyribonucleic acid synthesis in zygotes and vegetative cells of Saccharomyces cerevisiae; Lee E et al.; The synthesis of mitochondrial deoxyribonucleic acid (DNA) in Saccharomyces cerevisiae cells has been examined during conjugation, in preconjugal conditions, and in control cultures that were not exposed to obverse diffusible sex factors . The ratios of mitochondrial to nuclear DNA varied from about 0.1 in control cells, to about 0.3 in alpha cells exposed for 180 min to cell-free culture medium from a cells, and to about 0.4 in conjugating cells 150 min after mixing . The enhanced levels of mitochondrial DNA during preconjugal and conjugal conditions seem correlated with enhanced cell volumes . Likewise, amounts of mitochondrial DNA in vegetative cells were found to be correlated with cytoplasmic volumes.

Biotechnol Bioeng, 1977 Feb, 19(2), 199 - 210
Properties of intracellular ribonuclease utilized for RNA reduction in disintegrated cells of Saccharomyces cerevisiae; Lindblom M; The properties of intracellular RNase in disintegrated cell suspensions of Saccharomyces cerevisiae have been studied . The influence of salt addition and/or incubation of the suspension on the activity of RNase and on the degradation of endogenous RNA was determined . No significant change in the RNase activity in the disintegrated suspensions was obtained by addition of 3% NaCl or by incubation at 50 degrees C with 3% NaCl . During the incubation with NaCl the active RNase was able to degrade endogenous RNA . By incubation without salt the RNase was inactivated . Inactivation also occurred after extraction at alkaline pH . The RNase had an optima at pH 5-6 and temperatures between 50-60 degrees C . The main part of the RNase in the unincubated suspension was soluble also at pH 4.0 . No serious protein degradation occurred during the short time incubation needed for RNA reduction . 70% of the protein in the suspensions was recovered in the precipitate at pH 4.0 after 20 min of incubation . The corresponding protein recovery from unincubated suspensions was 77%.

J Biol Chem, 1977 Jan 25, 252(2), 671 - 76
A protein inhibitor of mitochondrial adenosine triphosphatase (F1) from Saccharomyces cerevisiae; Ebner E et al.; A heat-stable protein has been detected in Saccharomyces cerevisiae which inhibits mitochondrial ATPase activity . The protein inhibitor has been isolated from extracts prepared by brief heat treatment of unbroken cell suspensions . The isolated inhibitor is a small basic protein (molecular weight close to 7000, isoelectric proint 9.05) devoid of tryptophan, tyrosine, and cysteine as well as proline . The NHP2-terminal amino acid is serine . The ultraviolet absorption spectrum shows the vibrational fine structure of the phenyl-alanine band . Like the ATPase inhibitor from bovine heart mitochondria the yeast inhibitor is rapidly destroyed by trypsin . It is also inactivated by the yeast proteinases A and B . Radioimmunological analysis indicates that the inhibitor is synthesized on cytoplasmic ribosomes . Its accumulation seems to be connected to the formation of the mitochondrial ATPase complex, since its specific activity is greatly reduced both in extracts obtained from the F1-ATPase-deficient nuclear mutant pet 936 and from the cytoplasmic petite mutant D 273-10B-1.

Biochim Biophys Acta, 1977 Jan 20, 474(2), 245 - 53
Toyocamycin inhibition of ribosomal ribonucleic acid processing in an osmotic-sensitive adenosine-utilizing Saccharomyces cerevisiae mutant; Venkov PV et al.; An adenosine-utilizing mutant of Saccharomyces cerevisiae (SY 15 ado) is isolated after remutagenesis of an osmotic-sensitive strain, auxotrophic for adenine, with ethyl methanesulfonate . It is shown that the SY15ado mutant can be used to achieve experimental conditions under which cell growth and RNA Synthesis are directly dependent on exogenous adenosine . After starvation for adenosine, toyocamycin is incorporated into pre-rRNA chains of SY15ado cells replacing adenosine residues . The extent of this replacement depends on the concentration of added toyocamycin . Lower doses slow down processing of pre-rRNA into mature rRNA with an accumulation of 27 S and 20 S pre-rRNA . At higher concentrations toyocamycin blocks the last steps of pre-rRNA processing i.e . the conversions 27 S pre-rRNA leads to 25 S rRNA and 20 S pre-rRNA leads to 18 S rRNA . It appears that the main site of toyocamycin action is at the last steps of ribosome formation, while transcription and the early stages of pre-RNA processing are less affected.

Biochem J, 1977 Jan 15, 162(1), 51 - 9
An oligomycin-resistant adenosine triphosphatase and its effects on cellular growth, mitochondrial oxidative phosphorylation and respiratory proton translocation in Saccharomyces cerevisiae; Somlo M et al.; Mutations at the OLI 1 or OLI 2 loci of mitochondria DNA in Saccharomyces cerevisiae are associated with a diminished growth rate in nutritionally suboptimal cultures supplemented with an oxidizable carbon source . In the case of mutant OR146(OLI1) there is a 35% loss of mitochondrial protein during fractionation in vitro, suggesting that the mutationally altered adenosine triphosphatase(ATPase) confers some instability on the mitochondrial membrane . The possibility is discussed that this reflects an unstable mitchondrial population in vivo, leading the observed growth deficiency . Mitochondria from mutant OR146 at the OLI 1 locus show a relatively oligomycin-resistant State-3 respiration, but the same ADP/O and respiratory-control quotients as the isonuclear wild-type . A slightly lowered Qo2 with NADH-linked substrates was observed and is discussed . For both strains the apparent H+/O ratios were close to 4 with pyruvate, ethanol and alpha-oxoglutarate, but consistently lower with succinate and citrate . For each substrate a characteristic t 1/2 (time for half-decay of the transmembrane pH differential) range was found, consistent with the view that the substrates effecitvely carry the protons back across the membrane . As expected, H+/O ratios were independent of t 1/2 for all substrates, with the exception of alpha-oxoglutarate in the case of the wild-type, where an inverse correlation was found . The lack of this correlation in the case of the mutant was the only apparent difference in the translocation parameters observed . A hypothesis relating this to the functioning of the oligomycin-resistant ATPase is proposed.

Biochemistry, 1977 Jan 11, 16(1), 8 - 16
Characterization of purified poly(adenylic acid)-containing messenger ribonucleic acid from Saccharomyces cerevisiae; Holland MJ et al.; Yeast poly(adenylic acid)-containing messenger RNA was isolated from total cellular RNA by affinity chromatography on poly(uridylic acid)-cellulose . The relative complexity of the isolated yeast mRNA was assessed by hybridization analysis with complementary DNA synthesized from the isolated messenger RNA (mRNA) with viral reverse transcriptase . Approximately 25% of the mRNA hybridized at an apparent Crt1/2 of 5 X 10(-3) mol sl.(-1), while the remainder hybridized at an average Crt1/2 of 10(-1) mol sl.-1 . Poly(adenylic acid)-containing yeast mRNA was translated in vitro in a wheat germ cell-free extract, and the major polypeptides synthesized have the same molecular weight as the major proteins present in the cell . Four of these proteins were identified by coelectrophoresis and immune precipitation to be pyruvate kinase, enolase, aldolase, and glyceraldehyde-3-phosphate dehydrogenase . These data demonstrate in agreement with the hybridization results that yeast contains major mRNA species and that some of the glycolytic enzyme mRNAs make up part of the major fraction . A procedure is outlined for the preparation of yeast mRNA which is essentially free of ribosomal RNA contamination and is further enriched in the major mRNAs present in the cell.

Biochemistry, 1977 Jan 11, 16(1), 1 - 8
Isolation of ribonucleic acid polymerases I, II, and III from Saccharomyces cerevisiae; Hager GL et al.; A procedure for the simultaneous purification of RNA polymerases I, II, and III from Saccharomyces cerevisiae is described . High yields of each enzyme activity are obtained, allowing the preparation of approximately 10 mg of polymerase I, 25 mg of polymerase II, and 12 mg of polymerase III from 1.2 kg of cells (wet weight) . Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicates RNA polymerase I contains polypeptides with molecular weights 185 000, 137 000, 41 000, 35 000, 28 000, 24 000, 20 000, 16 000, 14 500, and 12 300; RNA polymerase II contains subunits with molecular weights 170 000, 145 000, 41 000, 33 500, 28 000, 24 000, 18 000, 14 500, and 12 500; and RNA polymerase III contains polypeptides with molecular weights 160 000, 128 000, 82 000, 53 000, 41 000, 37 000, 34 000, 28 000, 24 000, 20 000, 14 500, and 10 700.

Mol Gen Genet, 1977 Jan 7, 150(1), 81 - 6
Synthesis of cytochrome c oxidase polypeptides in an Escherichia coli cell-free system directed by Saccharomyces cerevisiae mitochondrial DNA; Scragg AH et al.; Using purified yeast mitochondrial DNA as a template for E . coli RNA polymerase (holoenzyme) complementary mitochondrial RNA has been synthesized in vitro . This RNA has been used to direct a low background E . coli S-30 protein-synthesizing system . The synthesis of mitochondrial polypeptides has been detected by using antiserum raised against purified cytochrome c oxidase holoenzyme and shown to be specific for this antigen . The antiserum-antigen complex was dissociated and subject to SDS-polyacrylamide gel electrophoresis and the presence of 3 polypeptides of 39, 31, and 26 X 10(3) daltons molecular weight demonstrated, which correspond to the subunits synthesized by mitochondria in whole cells which are inhibited with cycloheximide.

Acta Biol Med Ger, 1977, 36(11-12), 1525 - 30
Protein degradation during the differentiation of eukaryotic cells: studies on the sporulation of Saccharomyces cerevisiae and on the formation of the neuromuscular junction in the chick embryo; Betz H; The role of protein degradation in cell and tissue differentiation has been investigated during the sporulation of Saccharomyces cerevisiae and during endplate formation in developing avian muscle . The results suggest that a variety of proteolytic processes as enzyme inactivation, degradation of mitochondrial membrane constituents and removal of embryonic cell surface proteins exert stringent controls over the sequence of differentiation in eukaryotic cells.

Genetika, 1977, 13(5), 888 - 96
{Multiple mutants of Saccharomyces cerevisiae . III . The identification of the mutational changes that occur}; Aref'eva AIa et al.; Localization and molecular nature of mutations in multiple mutants of yeast Sacchromyces cerevisiae were studied . It was found that simultaneous changes in several genes located in more than five linkage groups took place during the arise of multiple mutants after a single UV-irradiation (at a dose of 300 erg/nm2) . It was shown that reversions of original nonsense-mutations were due to mutational changes in the same genes and the arise of the forward nonsense-mutations in the other genes took place as a result of base changes in DNA.

Cytobios, 1977, 18(69), 50 - 67
Nuclear envelope transport capacity and the cell cycle in yeast (Saccharomyces cerevisiae); Severs NJ; Changes in the nuclear envelope transport capacity, as measured by the number of nuclear pore complexes/unit nuclear volume/cell, were followed during the Saccharomyces cerevisiae cell cycle using data obtained by freeze-fracture electron microscopy . Pore number per unit nuclear volume decreased sharply in early G0, remained steady from mid-GO through S to G2, and showed a further slight decrease at M and G1 . These periods of decline apparently resulted from nuclear enlargement without sufficient formation of new nuclear pore complexes to maintain the pore number to nuclear volume ratio . However, marked nuclear pore formation did accompany both increases in nuclear volume . The significance of these changes in relation to other events in the cell cycle is discussed . The validity of using nuclear pore number/unit nuclear volume and other pore number data as indices of nuclear envelope transport capacity and cell activity is critically examined.

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