Mutat Res, 1982 Dec, 105(6), 403 - 7 Testing of Endosulfan and Fenitrothion for genotoxicity in Saccharomyces cerevisiae; Yadav AS et al.; Two insecticides, Endosulfan and Fenitrothion, were tested for their ability to induce mitotic crossing-over, mitotic gene conversion and reverse mutation in Saccharomyces cerevisiae . Treatment of cells with Endosulfan increased the frequencies of gene convertants and revertants . However, Fenitrothion treatment did not induce any of these genetic events. Fed Proc, 1982 Dec, 41(14), 3084 - 8 The biochemistry, genetics, and regulation of polyamine biosynthesis in Saccharomyces cerevisiae; Tabor CW et al.; We have studied the enzymes and genes involved in the biosynthesis of putrescine, spermidine, and spermine in Saccharomyces cerevisiae . Mutants have been isolated with defects in the biosynthetic pathway as follows: spe10 mutants, deficient in ornithine decarboxylase, cannot make putrescine, spermidine, or spermine; spe2 mutants, lacking S-adenosylmethionine decarboxylase, cannot make spermidine or spermine; spe3 mutants, lacking putrescine aminopropyltransferase, cannot make spermidine or spermine; and spe4 and spe40 mutants, lacking spermidine aminopropyltransferase, contain no spermine and permit growth of spe10 mutants . Studies with these mutants have shown that in yeast: 1) polyamines are absolutely required for growth; 2) putrescine is formed only by decarboxylation or ornithine; 3) two separate aminopropyltransferases are required for spermidine and spermine synthesis; 4) spermine and spermidine are important in the regulation of ornithine decarboxylase and the amines exert this control by a posttranslational modification of the enzyme; and 5) spermidine or spermine is essential for sporulation of yeast and for the maintenance of the double-stranded RNA killer plasmid . Recent studies in amine-deficient mutants of Escherichia coli have shown an important role of the polyamines in protein synthesis in vivo. J Bacteriol, 1982 Dec, 152(3), 1255 - 64 Activation of chitin synthetase in permeabilized cells of a Saccharomyces cerevisiae mutant lacking proteinase B; Fernandez MP et al.; Digitonin treatment at 30 degrees C of a Saccharomyces cerevisiae mutant lacking proteinase B permeabilized the cells and caused rapid and extensive activation of chitin synthetase in situ . The same result was obtained with a mutant generally defective in vacuolar proteases . By lowering the temperature and using different permeabilization procedures, we showed that increases in permeability and activation are distinct processes . Activation was inhibited by the protease inhibitors antipain and leupeptin, but by pepstatin or chymostatin . Metal chelators were also inhibitory, and their effect was reversed by the addition of Ca2+ but not by Mg2+ . Antipain added together with Ca2+ after incubation of the cells in the presence of a chelating agent prevented reversal of inhibition, a result that was interpreted as indicating that antipain acts either on the same step affected by Ca2+ or on a subsequent step . Efforts to obtain activation in cell-free extracts were unsuccessful, but it was possible to extract the synthetase, once activated, by breaking permeabilized cells with glass beads . Treatment of the cell-free extracts with trypsin led not only to increased activity of chitin synthetase, but also to a change in the pH-activity curve and a diminished requirement by the enzyme for free N-acetylglucosamine . These observations suggest that the modification undergone by the synthetase during endogenous activation is different from that brought about by trypsin treatment. Nucleic Acids Res, 1982 Nov 25, 10(22), 7283 - 93 Transcripts of mitochondrial tRNA genes in Saccharomyces cerevisiae; Frontali L et al.; The transcription of a group of tRNA genes from the large tRNA gene cluster of mitochondrial DNA from Saccharomyces cerevisiae has been investigated by hybridization with DNA probes carrying tRNA coding sequences and small portions of the A + T rich intergenic regions . Results have shown that in some rho- mutants (DS502, F11) mature tRNA was absent, but a few transcripts could be detected . Some high molecular weight species actually hybridized with DNA probes carrying different tRNA coding sequences . Low molecular weight transcripts (100-150 nucleotides, carrying one tRNA sequence) were also present in these mutants . A high molecular weight transcript was also observed in the wild type, though in much more limited amount . The low molecular weight transcripts were analysed by the S1 mapping technique and found to include both a tRNA sequence and the upstream 5' flanking region extending as far as the 3' end of the preceding tRNA gene . The results suggest the existence of a common transcript bearing several tRNA sequences and indicate a possible mechanism of processing, which might be defective in mutants. Biochim Biophys Acta, 1982 Nov 24, 719(2), 356 - 62 Transport and metabolic effects of alpha-aminoisobutyric acid in Saccharomyces cerevisiae; Kim KW et al.; alpha-Aminoisobutyric acid is actively transported into yeast cells by the general amino acid transport system . The system exhibits a Km for alpha-aminoisobutyric acid of 270 microM, a Vmax of 24 nmol/min per mg cells (dry weight), and a pH optimum of 4.1-4.3 . alpha-Aminoisobutyric acid is also transported by a minor system(s) with a Vmax of 1.7 nmol/min per mg cells . Transport occurs against a concentration gradient with the concentration ratio reaching over 1000:1 (in/out) . The alpha-aminoisobutyric acid is not significantly metabolized or incorporated into protein after an 18 h incubation . alpha-Aminoisobutyric acid inhibits cell growth when a poor nitrogen source such as proline is provided but not with good nitrogen sources such as NH+4 . During nitrogen starvation alpha-aminoisobutyric acid strongly inhibits the synthesis of the nitrogen catabolite repression sensitive enzyme, asparaginase II . Studies with a mutant yeast strain (GDH-CR) suggest that alpha-aminoisobutyric acid inhibition of asparaginase II synthesis occurs because alpha-aminoisobutyric acid is an effective inhibitor of protein synthesis in nitrogen starved cells. Eur J Biochem, 1982 Nov 15, 128(2-3), 589 - 95 Regulation of the phosphatidylethanolamine methylation pathway in Saccharomyces cerevisiae; Yamashita S et al.; 1 . Phosphatidyl-N-methylethanolamine methyltransferase mutants of Saccharomyces cerevisiae were isolated . Genetic analysis showed that phosphatidylethanolamine methyltransferase and phosphatidyl-N-methylethanolamine methyltransferase are coded for by separate genes . Phosphatidyl-N-methylethanolamine methyltransferase activity and phosphatidyl-N,N-dimethylethanolamine methyltransferase activity appeared to be catalyzed by the same enzyme . 2 . Phosphatidyl-N-methylethanolamine methyltransferase was found to be repressed by myo-inositol and choline . Both myo-inositol and choline at concentrations of 10 micrograms/ml were required for repression . The decreased enzyme level was restored by the removal of myo-inositol or choline or both . 3 . Both myo-inositol and choline were required for the maximum repression of phosphatidylethanolamine methyltransferase in wild-type cells . In contrast, choline was not required for the repression of the enzyme in mutant strain 172 . This was due to a single nuclear gene mutation in the genome of strain 172 . 4 . The activity of the phosphatidylethanolamine methylation pathway in cells decreased with time on incubation of cells with myo-inositol and choline, myo-Inositol could not be replaced by other structurally related compounds, such as scyllo-inositol or mannitol . 5 . The physiological significance of the repression of the phosphatidylethanolamine methylation pathway is discussed with respect to the mechanism for maintaining the contents of phosphatidylethanolamine and phosphatidylcholine at normal levels. J Biol Chem, 1982 Nov 10, 257(21), 13081 - 7 The amino acid sequence of cytochrome c oxidase subunit VI from Saccharomyces cerevisiae; Gregor I et al.; The complete amino acid sequence of the nuclearly coded cytochrome c oxidase subunit VI was determined for a genetically defined haploid strain of Saccharomyces cerevisiae . The subunit contains 108 amino acids, has Mr = 12,627, is acidic (net charge of -9.7 at pH 7) and is quite polar (polarity index, 50.9%) . Distribution of charges within the polypeptide chain is highly non-random . The NH2- and COOH-terminal regions are predominantly acidic whereas an apolar and a basic region are found in the interior, Subunit VI shows between 28 and 40% sequence homology (depending on the method of alignment) with subunit V of bovine cytochrome c oxidase; since the yeast subunit VI lacks methionine and contains only a single histidine residue very close to the NH2 terminus, it is unlikely that either of the two subunits carries heme alpha in the native enzyme. Mol Cell Biol, 1982 Nov, 2(11), 1399 - 409 Chromosomes XIV and XVII of Saccharomyces cerevisiae constitute a single linkage group; Klapholz S et al.; We present several lines of evidence that chromosomes XIV and XVII of Saccharomyces cerevisiae are not independent chromosomes, but rather constitute a single linkage group . Studies which made use of a new mapping method based on the haploidization-without-recombination meiotic phenotype of the spoll mutant initially indicated that markers on chromosomes XIV and XVII were linked . Tetrad analysis was used to establish gene-gene distances, and a new chromosome XIV map incorporating markers originally assigned to chromosome XVII was derived . During the course of trisomic segregation studies, we discovered that a 2n + 2 homothallic diploid, originally believed to be tetrasomic for chromosome XVII (now XIV), carries two normal chromosome XIV homologs and two aberrant homologs which appear to be deficient for a large portion of the right arm of XIV . The previous evidence that established chromosome XVII as an independent linkage group is discussed in the light of these findings. Mol Cell Biol, 1982 Nov, 2(11), 1299 - 303 Propranolol, atenolol, and trifluoperazine reduce the spontaneous occurrence of meiotic diploid products in Saccharomyces cerevisiae; Sora S et al.; The effect of atenolol, propranolol, trifluoperazine, and caffeine on the occurrence of meiotic diploid and disomic products in Saccharomyces cerevisiae was investigated . We demonstrated that atenolol, propranolol, and trifluoperazine reduce the occurrence of meiotic diploid products and that propranolol also slightly decreases the spontaneous frequency of disomics . On the other hand, caffeine appears to be a powerful inducer of diploid meiotic products, but also shows a lesser effect on disomic induction . Since spontaneous or caffeine-induced diploids arise from a failure of the second meiotic division, it appears that the target of these drugs is at the beginning of the second meiotic division . The only common effect of trifluoperazine and propranolol, mainly investigated in mammals, was an inhibition of calmodulin activity via direct interaction . We tend, therefore, to believe that calmodulin activity must be a crucial point for the second meiotic division to begin . The increased induction of diploids, due to caffeine, may be interpreted as a consequence of an increased cyclic AMP level. Mikrobiologiia, 1982 Nov-Dec, 51(6), 901 - 4 {Increased permeability of the intracellular membranes in the dehydration and rehydration of Saccharomyces cerevisiae yeasts}; Rapoport AI et al.; A considerable quantity of potassium and magnesium ions was found to be released from Saccharomyces cerevisiae cells being in the state of anabiosis upon their rehydration . The nearly maximal (for each of the experiments) quantity of ions was released as early as when cells dehydrated to a residual humidity of ca . 20% were rehydrated . A further decrease of the residual humidity down to 8-10% did not increase the leakage of the ions when the cells were rehydrated . It was concluded that the permeability of the cytoplasmic and vacuolar membranes for the ions increased when the cells were dehydrated and that this phenomenon should be attributed to the removal of free water from the cells. J Gen Microbiol, 1982 Nov, 128 (Pt 11), 2591 - 600 Accumulation of 2'-O-methylguanosine deficient tRNATrp in tryptophan limited Saccharomyces cerevisiae; Staheli P et al.; Saccharomyces cerevisiae synthesizes one major tryptophan transfer ribonucleic acid (tRNATrp) species (isoacceptor A) carrying characteristic base modifications . Under tryptophan limited growth conditions wild-type strain X2180-1A exhibited a second important tRNATrp species (isoacceptor B) . The total amount of tRNATrp, approximately 2.5 pmol (mg dry wt)-1, stayed essentially constant during amino acid shift-down experiments . The amount of isoacceptor B relative to total tRNATrp was 10 to 15% during amino acid sufficient exponential growth conditions, but increased during tryptophan limitation three- to four-fold . Analysis of the base compositions showed that isoacceptor B differed from isoacceptor A in one respect only: 2'-O-methylguanosine, a modified guanosine base occurring at position 17 of the major isoacceptor A tRNATrp, was not detectable in hydrolysates of purified isoacceptor B . The biological significance of isoacceptor B is discussed. Genetics, 1982 Nov, 102(3), 361 - 78 Frameshift suppression in Saccharomyces cerevisiae . V . Isolation and genetic properties of nongroup-specific suppressors; Culbertson MR et al.; Two classes of frameshift suppressors distributed at 22 different loci were identified in previous studies in the yeast Saccharomyces cerevisiae . These suppressors exhibited allele-specific suppression of +1 G:C insertion mutations in either glycine or proline codons, designated as group II and group III frameshift mutations, respectively . Genes corresponding to representative suppressors of each group have been shown to encode altered glycine or proline tRNAs containing four base anticodons.--This communication reports the existence of a third class of frameshift suppressor that exhibits a wider range in specificity of suppression . The suppressors map at three loci, suf12, suf13, and suf14, which are located on chromosomes IV, XV, and XIV, respectively . The phenotypes of these suppressors suggest that suppression may be mediated by genes other than those encoding the primary structure of glycine or proline tRNAs. J Bacteriol, 1982 Nov, 152(2), 874 - 9 Growth inhibition by alpha-aminoadipate and reversal of the effect by specific amino acid supplements in Saccharomyces cerevisiae; Winston MK et al.; The growth of Saccharomyces cerevisiae wild-type strain X2180 in minimal medium was inhibited by the addition of higher-than-supplementary levels of alpha-aminoadipate . This inhibitory effect was reversed by the addition of arginine, asparagine, aspartate, glutamine, homoserine, methionine, or serine as single amino acid supplements . Mutants belonging to the lys2 and lys14 loci were able to grow in lysine-supplemented alpha-aminoadipate medium, although not as well as when selected amino acids were added . Growth in alpha-aminoadipate medium by all strains was accompanied by an accumulation of alpha-ketoadipate . Glutamate:keto-adipate transaminase levels were derepressed two- to fivefold in lys2 mutants using alpha-aminoadipate as a nitrogen source . Wild-type strain X2180 growing in amino acid-supplemented AA medium exhibited higher levels of alpha-aminoadipate reductase . Mutants unable to use alpha-aminoadipate without amino acid supplementation were obtained by treatment of lys2 strain MW5-64 and were shown to have glutamate: ketoadipate transaminase activity and to lack alpha-aminoadipate reductase activity . Altered cell morphologies, including increased size, multiple buds, pseudohyphae, and germ tubes, evidenced by cells grown in alpha-aminoadipate medium suggest that higher-than-supplementary levels of alpha-aminoadipate result in an impairment of cell division. J Bacteriol, 1982 Nov, 152(2), 747 - 56 Effects of unsaturated fatty acid deprivation on neutral lipid synthesis in Saccharomyces cerevisiae; Buttke TM et al.; The effects of unsaturated fatty acid deprivation on lipid synthesis in Saccharomyces cerevisiae strain GL7 were determined by following the incorporation of {14C}acetate . Compared to yeast cells grown with oleic acid, unsaturated fatty acid-deprived cells contained 200 times as much 14C label in squalene, with correspondingly less label in 2,3-oxidosqualene and 2,3;22,23-dioxidosqualene . Cells deprived of either methionine or cholesterol did not accumulate squalene, demonstrating that the effect of unsaturated fatty acid starvation on squalene oxidation was not due to an inhibition of cell growth . Cells deprived of olefinic supplements displayed additional changes in lipid metabolism: (i) an increase in 14C-labeled diacylglycerides, (ii) a decrease in 14C-labeled triacylglycerides, and (iii) increased levels of 14C-labeled decanoic and dodecanoic fatty acids . The changes in squalene oxidation and acylglyceride metabolism in unsaturated fatty acid-deprived cells were readily reversed by adding oleic acid . Pulse-chase studies demonstrated that the {14C}squalene and 14C-labeled diacylglycerides which accumulated during starvation were further metabolized when cells were resupplemented with oleic acid . These results demonstrate that unsaturated fatty acids are essential for normal lipid metabolism in yeasts. Genetics, 1982 Nov, 102(3), 341 - 59 Mutations in the pho80 gene confer permeability to 5'-mononucleotides in Saccharomyces cerevisiae; Bisson LF et al.; Yeast mutants permeable to dTMP (tup) were selected and two new complementation groups (tup5 and tup7) were identified . Assay of the levels of both acid and alkaline phosphatase in cells grown under either repressing (5 mM PO4(-3) or derepressing (0.03 mM PO4(-3) conditions indicated that, in general, tup mutations cause cells to be defective in their regulation of phosphatase synthesis . In addition, three of the tup mutations (tup1, tup4 and tup7) displayed markedly elevated rates of inorganic phosphate transport . The tup7 locus was found to be tightly centromere-linked on the right arm of chromosome XV, and was shown to be allelic with the pho80 regulatory locus on the basis of both genetic and biochemical criteria . Analysis of other mutations known to affect phosphatase levels (pho) indicated that some also conferred permeability to dTMP . Possible allelic relationships between tup genes and certain of these pho mutations are discussed . Regardless of the culture conditions, wild-type strains were not permeable to dTMP; in contrast, it was found in the course of this work that normal yeast cells were permeable to dUMP and that dUMP permeability was regulated by the concentration of inorganic phosphate present in the medium used to grow the cells . Thus, permeability to 5'-mononucleotides appears to be under coordinate control with phosphatase synthesis. Eur J Biochem, 1982 Nov, 128(1), 179 - 84 Regulation of synthesis of catalases and iso-1-cytochrome c in Saccharomyces cerevisiae by glucose, oxygen and heme; Hortner H et al.; The regulation of the hemoproteins catalase T, catalase A and iso-1-cytochrome c was studied in the yeast Saccharomyces cerevisiae . Levels of catalase T and catalase A mRNAs are low or undetectable in anaerobic and heme-deficient cells, and in wild type strains grown on high glucose concentrations . Regulatory mutants (cgr4 and cas1), which have previously been shown to have high catalase T activity when grown in the absence of oxygen or on high glucose concentrations, have high levels of catalase T mRNA when grown under glucose repression conditions . Whereas no catalase T mRNA could be detected in a heme-deficient (ole3) single mutant, double mutants (ole3 cgr4) and (ole3 cas1) contain mature catalase T mRNA . Catalase T and A mRNAs are accumulated rapidly during adaptation of anaerobic cells to oxygen . Anaerobic and heme-deficient cells lack or have extremely low levels of iso-1-cytochrome c mRNA, which, like catalase mRNAs, is accumulated rapidly during oxygen adaptation . The results obtained demonstrate that glucose, oxygen and heme regulate the synthesis of the hemoproteins studied by controlling mRNA levels . In addition, posttranscriptional, probably translational control has to be postulated at least in the case of catalases, to explain the results obtained. Biochim Biophys Acta, 1982 Oct 14, 713(1), 86 - 93 Lipid synthesis in inositol-starved Saccharomyces cerevisiae; McCammon MT et al.; Lipid synthesis was analyzed in an inositol-requiring mutant of Saccharomyces cerevisiae (MC13) . Both rates and cellular amounts of {U-14C}acetate incorporation into phospholipids, triacylglycerols, free sterols and steryl esters were elevated in an inositol-starved culture compared to the supplemented control at a time when the deprived culture was losing viability (inositol-less death) . The rates at a later time were greatly reduced . During the period when de novo lipid synthesis was high in the starved culture, phospholipid turnover and presumed conversion to triacylglycerols was also accelerated; no differences were apparent in the turnover of the sterol fractions between the two cultures . No change in the fractional percent of ergosterol or of the sterol precursors could be attributed to inositol starvation . The synthesis and maintenance of membrane lipids (phospholipids and free sterols) and their coupling in cellular metabolism are discussed in light of these results. J Biol Chem, 1982 Oct 10, 257(19), 11203 - 6 In vivo biosynthesis of the vacuolar proteinases A and B in the yeast Saccharomyces cerevisiae; Mechler B et al.; Proteinase A and proteinase B, two vacuolar enzymes in Saccharomyces cerevisiae, are synthesized as larger precursors with apparent molecular weights of approximately 52,000 and 42,000, respectively . These precursor molecules are processed to their mature forms of 42,000 molecular weight for proteinase A and 33,000 molecular weight for proteinase B . In the presence of tunicamycin, an inhibitor of the synthesis of protein-asparagine linked carbohydrate moieties, two smaller molecular forms each of precursor and mature proteinase A were synthesized, indicating that proteinase A contains N-linked carbohydrate which is apparently not required for processing . Tunicamycin interferes also with the glycosylation of the proteinase B precursor, whereas no unglycosylated mature proteinase B could be detected. Biochimie, 1982 Oct, 64(10), 859 - 65 {Biosynthesis and metabolism of phosphonolipids and phospholipids in rat hepatocytes and Saccharomyces cerevisiae}; Baraud J et al.; In rat hepatocytes, ciliatine (2 aminoethylphosphonic acid) is incorporated into phosphonolipid (PnE) by the same pathway leading from phosphorylethanolamine to phospholipid (PE) . The two resulting lipids are isolated from mitochondria and microsomes . The rates of biosynthesis are quite comparable; the processes of trimethylation and of in vitro transfer in the presence of a specific exchange protein are very similar . In yeast, on the other hand, the uptake of the two precursors is very slight, suggesting that the direct cytidylic pathway of phospholipid biosynthesis is strongly repressed . Despite small amounts of PE and PnE produced, methylation occurs with a good yield . The good incorporation of ethanolamine may be understood by a base-exchange mechanism . The natural PE biosynthesis is achieved through the decarboxylation of phosphatidylserine, and followed by methylation leading to phosphatidylcholine . The use of very small amounts of precursors does not modify the natural course of phospholipid biosynthesis. Z Naturforsch {C}, 1982 Oct, 37(10), 916 - 20 The Triton X-100 and high salt resistant residue of Saccharomyces cerevisiae nuclear membranes; Mann K et al.; Saccharomyces cerevisiae nuclear membranes were prepared from isolated nuclei by digesting chromatin with deoxyribonuclease after an initial treatment of nuclei with very diluted buffers . When the nuclear membranes were treated with 5% Triton X-100 and 1M NaCl an insoluble fibrous net was obtained which consisted mainly of protein with Mr values of 85 000, 48 000, 45 000, 39 000 and 31 000 . Lamins, a set of proteins with Mr = 65 000--75 000, which were shown to be the major proteins of the insoluble nuclear membrane residue of higher eukaryotes, were not found. Mol Cell Biol, 1982 Oct, 2(10), 1205 - 11 Further evidence that the rna2 mutation of Saccharomyces cerevisiae affects mRNA processing; Bromley S et al.; The relative rate at which ribosomal protein 51 (rp51) mRNA is synthesized was measured by pulse-labeling cells in vivo with {3H}adenine . Two strains of Saccharomyces cerevisiae were compared: A364A (wild type) and ts368 (rna2), a temperature-sensitive strain in which the level of rp51 mRNA decreases and an intron-containing rp51 precursor RNA increases . When cells were shifted up to the nonpermissive temperature (36 degrees C), the rate of rp51 RNA synthesis was only marginally affected (75% of wild type) by the presence of the rna2 mutation . The precursor RNA was the predominant transcription product at 36 degrees C . This precursor could be converted into RNA equal in size to mature mRNA by further incubation at either 36 or 23 degrees C in the presence of unlabeled adenine . The relative half-life of the rp51 transcripts at 36 degrees C also decreased approximately twofold in ts368 as compared with A364A . All of these data imply that the precursor (intron-containing) RNA is processed inefficiently to mature mRNA and that the rp51 precursor RNA is continuously synthesized and degraded in the mutant strain at 36 degrees C. Mol Cell Biol, 1982 Oct, 2(10), 1199 - 204 Sporulation and rna2 lower ribosomal protein mRNA levels by different mechanisms in Saccharomyces cerevisiae; Kraig E et al.; In Saccharomyces cerevisiae, the levels of ribosomal protein mRNAs are regulated coordinately . Vegetative strains carrying the temperature-sensitive rna2 mutation exhibit a dramatic decrease in the levels of most ribosomal protein mRNAs at the restrictive temperature . Similarly, in wild-type cells induced to sporulate by nitrogen starvation, there is a fivefold reduction in the relative synthesis rate of ribosomal proteins . Using Northern gel analysis and cloned ribosomal protein genes, we compared the way in which ribosomal protein mRNA is affected under these two conditions . In vegetative rna2 cells, incubation at 34 degrees C led to the disappearance of ribosomal protein mRNAs and the accumulation of higher-molecular-weight precursor RNAs . A different phenotype was observed during sporulation . Although sporulating conditions led to a significant reduction in the relative abundance of ribosomal protein mRNA, there was no detectable accumulation of precursor RNAs even in rna2/rna2 diploids at 34 degrees C . A suppressor of rna2 and of other rna mutations, SRN1, at least partially relieved the block in the splicing of the ribosomal protein 51 intron in vegetative rna2 cells but did not detectably affect the level of ribosomal protein mRNA in sporulating cells . We concluded that the rna2 mutation and sporulation conditions affected ribosomal protein mRNA metabolism in two quite different ways . In vegetative cells the mutant rna2 effected a block which occurred primarily in post-transcriptional processing, whereas in sporulating cells the ribosomal protein mRNA levels were decreased by some other mechanism, presumably a change in the relative rate of transcription or mRNA turnover . Furthermore, the data suggest that the mutation rna2 has no additional effect on ribosomal protein mRNA metabolism in sporulating cells. Proc Natl Acad Sci U S A, 1982 Oct, 79(20), 6191 - 5 Specific interactions of Saccharomyces cerevisiae proteins with a promoter region of eukaryotic tRNA genes; Klemenz R et al.; The specific binding of one or several Saccharomyces cerevisiae proteins to a segment of genes that code for different yeast tRNAs has been demonstrated with the use of the DNase I-protection "footprint" assay of Galas and Schmitz . The analyzed binding occurs near the 3' ends of the genes and is centered on an 11-base-pair DNA sequence that has been well conserved among eukaryotic tRNA genes . Others have shown the involvement of this sequence in initiating the transcription of tRNA genes by RNA polymerase III . The adenovirus gene that codes for VAI RNA also contains this conserved sequence element, and we detect binding of yeast protein(s) to this gene . Competition experiments show that a common set of proteins binds to different tRNA genes . The DNA-protein complex is quite stable at 20 degrees C and low ionic strength. Mutat Res, 1982 Oct-Nov, 102(3), 249 - 59 Genetic effects of ozone: induction of point mutation and genetic recombination in Saccharomyces cerevisiae; Dubeau H et al.; The mutagenicity and recombinogenicity of the atmospheric pollutant, ozone, were investigated in several strains of Saccharomyces cerevisiae . It was observed that ozone induced a variety of genetic events, such as forward and reverse mutations as well as gene conversion and mitotic crossing-over . However, when compared to known mutagens like ultraviolet light, X-rays and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), ozone appeared to be a weak mutagen. Eur J Biochem, 1982 Oct, 127(2), 411 - 6 Mitochondrial transcripts in glucose-repressed cells of Saccharomyces cerevisiae; Baldacci G et al.; We have compared mitochondrial transcripts from yeast Saccharomyces cerevisiae strain D273-10B grown in the presence of 2% galactose (non-repressed cells) or 15% glucose (glucose-repressed cells) . The ethidium-bromide-stained electrophoretic pattern of mitochondrial RNAs from glucose-repressed cells shows a clear decrease of tRNAs . In addition, some RNA bands appear to be specific for a single growth condition . To identify these RNA species we have performed hybridization experiments with 32P-labelled mitochondrial DNA from petite mutant cells . The mitochondrial repeat units of the mutants retained only one of the following genes: oxi1, oxi2, oxi3, oli2, cob and oli1 . Unchanged amounts of oxi2 and oli2 transcripts and reduced concentrations of oli1 and oxi1 putative mRNAs are present in glucose-repressed cells . In the same growth condition we observe a decreased processing of a precursor RNA species from the split cob gene and reduced amounts of transcripts corresponding to the first, second and fifth intron of the split oxi3 gene . The oxi3 first and second introns, whose transcripts are the most variable, include long open reading frames in their nucleotide sequence, but at present it is not known whether the corresponding RNA species have a functional role . Our results show that their concentrations are related to the growth condition. Eur J Biochem, 1982 Oct, 127(2), 339 - 42 Reduction of respiratory-chain cytochrome b by lactate in Saccharomyces cerevisiae; Briquet M et al.; Cytochrome b of yeast mitochondria can be reduced by a part of the electrons resulting from the oxidation of lactate enantiomers . 1 . The respiration of D-lactate and L-lactate is 30-40% inhibited by antimycin A . 2 . Reduction of cytochrome b is observed in submitochondrial particles in the presence of low concentration of D-lactate and L-lactate (half-optimal concentration of 4.7 mM and 2.4 mM respectively) in the presence of different bc1 inhibitors . 3 . Reduction of cytochrome b and c1 occurs in purified complex III of yeast in the presence of L-lactate and added L-lactate: NAD+ oxidoreductase . 4 . In the particles obtained from yeast grown in lactate the oxidation of L-lactate involves the reduction of a pigment absorbing at 558 nm. J Bacteriol, 1982 Oct, 152(1), 517 - 20 DNA replication in a diploid strain of Saccharomyces cerevisiae homozygous for the rad6-1 mutation; Haladus E et al.; The generation time of a diploid strain homozygous for the rad6-1 mutation was 160 min, and the duration of the S phase was 80 min; in the parental heterozygote, these values were 90 and 40 min, respectively . Analysis of DNA sedimentation in an alkaline sucrose gradient revealed that heterozygote high-molecular-weight DNA appeared after 60 min, and homozygote high-molecular weight DNA only after a 100-min pulse. J Bacteriol, 1982 Oct, 152(1), 111 - 9 Exogenous dTMP utilization by a novel tup mutant of Saccharomyces cerevisiae; Bisson LF et al.; The rate and extent of entry of dTMP were measured in strains of Saccharomyces cerevisiae carrying two new tup mutations (tup5 and tup7) and most of the other tup mutations which have been reported previously by others . The tup7 mutation allowed dramatically greater accumulation of dTMP than any of the other mutations tested . Specific labeling of DNA by {CH3-3H}dTMP, fate of the dTMP pool inside of the cells, and degradation of the dTMP in the culture medium were investigated in strains carrying the tup7 mutation . The extracellular dTMP was not appreciably degraded, and that accumulated intracellularly was readily phosphorylated to dTDP and dTTP . Under optimum labeling conditions, 60 to 80% of the total thymidylate residues in newly synthesized DNA were derived from the exogenously provided dTMP, even in the absence of a block in de novo dTMP biosynthesis . An apparent Km for entry of 2 mM dTMP was found . The tup7 mutation increased permeability to dTMP (and some other 5'-mononucleotides), but did not affect uptake of nucleosides and purine and pyrimidine bases . Uptake of dTMP could be almost completely inhibited by moderate concentrations of Pi . These findings and other observations suggest that entry of dTMP in strains carrying the tup7 mutation is mediated by a permease whose function in normal cells is the transport of Pi. J Biol Chem, 1982 Sep 25, 257(18), 10846 - 51 Analysis of temperature-sensitive mutant ts 187 of Saccharomyces cerevisiae altered in a component required for the initiation of protein synthesis; Feinberg B et al.; Postpolysomal extracts have been prepared from wild type haploid Saccharomyces cerevisiae cells (wt A364A) and from a temperature-sensitive mutant strain (ts 187, gene prt 1) . The extracts, prepared via spheroplasts and depleted of endogenous mRNA with nuclease, translate exogenous natural mRNA and polyuridylic acid . The activity of wt A364A with respect to translation of yeast mRNA, poly(U)-dependent synthesis of polyphenylalanine which measures elongation components, reactions involved in the initiation of protein synthesis, and termination and release of polypeptides, is not significantly affected when spheroplasts are incubated at 39 degrees C for relatively short periods of time, prior to the preparation of the cell-free system . With extracts obtained from ts 187 cells, preincubation of spheroplasts at 39 degrees C prior to the preparations of the cell-free system markedly decreases the ability to translate natural mRNA but not poly(U) . Compared to extracts from unheated spheroplasts, the following activities in ts 187 extracts from spheroplasts preincubated at 39 degrees C are not significantly affected: activation of methionine and methionylation of tRNAMet; formation of (eukaryotic initiation factor 2.Met-tRNAf.GTP} ternary complex; binding of mRNA to 40S preinitiation intermediate containing Met-tRNAf, and joining of 60S subunits to form the 80S initiation complex; elongation factor 1- and elongation factor 2-dependent elongations reactions; and termination and release of completed polypeptide chains . However, the interaction between the {eukaryotic initiation factor 2.Met-tRNAf.GTP} ternary complex and 40 S subunits, to form the 40 S preinitiation complex, is drastically inhibited by treatment of the spheroplasts at 39 degrees C. Biochim Biophys Acta, 1982 Sep 24, 691(1), 144 - 50 L-Proline transport in Saccharomyces cerevisiae; Horak J et al.; Transport of L-proline into Saccharomyces cerevisiae K is mediated by two systems, one with a KT of 31 microM and Jmax of 40 nmol . s-1 . (g dry wt.)-1, the other with KT greater than 2.5 mM and Jmax of 150-165 nmol . s-1 . (g dry wt.)-1 . The kinetic properties of the high-affinity system were studied in detail . It proved to be highly specific, the only potent competitive inhibitors being (i) L-proline and its analogs L-azetidine-2-carboxylic acid, sarcosine, D-proline and 3,4-dehydro-DL-proline, and (ii) L-alanine . The other amino acids tested behaved as noncompetitive inhibitors . The high-affinity system is active, has a sharp pH optimum at 5.8-5.9 and, in an Arrhenius plot, exhibits two inflection points at 15 degrees C and 20-21 degrees C . It is trans-inhibited by most amino acids (but probably only the natural substrates act in a trans-noncompetitive manner) and its activity depends to a considerable extent on growth conditions . In cells grown in a rich medium with yeast extract maximum activity is attained during the stationary phase, on a poor medium it is maximal during the early exponential phase . Some 50-60% of accumulated L-proline can leave cells in 90 min (and more if washing is done repeatedly), the efflux being insensitive to 0.5 mM 2,4-dinitrophenol and uranyl ions, the pH between 3 and 7.3, as well as to the presence of 10-100 mM unlabeled L-proline in the outside medium . Its rate and extent are increased by 1% D-glucose and by 10 micrograms nystatin per ml. J Bacteriol, 1982 Sep, 151(3), 1123 - 8 New genes involved in carbon catabolite repression and derepression in the yeast Saccharomyces cerevisiae; Entian KD et al.; A mutation causing resistance to carbon catabolite repression in gene HEX2, mutant allele hex2-3, causes an extreme sensitivity to maltose when in combination with the genes necessary for maltose metabolism . This provided a convenient system for the selective isolation of mutations in genes specifically required for maltose metabolism and other genes involved in general carbon catabolite repression . In addition to reversion of the hex2-3 allele, mutations in three other genes were detected . These genes were called CAT1, CAT3, and MUR1 and in a mutated form abolished maltose inhibition caused by mutant allele hex2-3 . Mutant alleles cat1 and cat3 also restored normal repression in the presence of the hex2-3 allele . Segregants having only mutant alleles cat1 or cat3 were obtained by tetrad analysis . These segregants could not grow on nonfermentable carbon sources . Mutant alleles of gene CAT1 were allelic to a mutant allele cat1-1 previously isolated (Zimmermann et al., Mol . Gen . Genet . 151:95-103) . Such mutants prevented derepression not only of the maltose catabolizing system, the selected property, but also of glyoxylate shunt and gluconeogenic enzymes . However, respiratory activities and invertase formation were not affected under derepressing conditions . cat3 mutants had the same phenotypic properties as cat1 mutants . This showed that carbon metabolism in yeast cells is under a very complex and ramified control of repressing and derepressing genes, which are interdependent. Mol Cell Biol, 1982 Sep, 2(9), 1088 - 95 Isolation and characterization of mutants that produce the allantoin-degrading enzymes constitutively in Saccharomyces cerevisiae; Chisholm G et al.; Degradation of allantoin, allantoate, or urea by Saccharomyces cerevisiae requires the participation of four enzymes and four transport systems . Production of the four enzymes and one of the active transport systems is inducible; allophanate, the last intermediate of the pathway, functions as the inducer . The involvement of allophanate in the expression of five distinct genes suggested that they might be regulated by a common element . This suggestion is now supported by the isolation of a new class of mutants (dal80) . Strains possessing lesions in the DAL80 locus produce the five inducible activities at high, constitutive levels . Comparable constitutive levels of activity were also observed in doubly mutant strains (durl dal80) which are unable to synthesize allophanate . This, with the observation that arginase activity remained at its uninduced, basal level in strains mutated at the DAL80 locus, eliminates internal induction as the basis for constitutive enzyme synthesis . Mutations in dal80 are recessive to wild-type alleles . The DAL80 locus has been located and is not linked to any of the structural genes of the allantoin pathway . Synthesis of the five enzymes produced constitutively in dal80-1-containing mutants remains normally sensitive to nitrogen repression even though the dal80-1 mutation is present . From these observations we conclude that production of the allantoin-degrading enzymes is regulated by the DAL80 gene product and that induction and repression of enzyme synthesis can be cleanly separated mutationally. Mol Cell Biol, 1982 Sep, 2(9), 1080 - 7 Mitotic chromosome loss induced by methyl benzimidazole-2-yl-carbamate as a rapid mapping method in Saccharomyces cerevisiae; Wood JS; Mitotic chromosome loss induced by methyl benzimidazole-2-yl-carbamate has been utilized as a rapid and simple method for assigning genes to individual chromosomes in Saccharomyces cerevisiae . This technique relied on the segregation of heterozygous markers in a diploid strain after methyl benzimidazole-2-yl-carbamate treatment due to loss of whole chromosomes . Correlations between the expression of an unmapped gene and that of a previously mapped recessive marker indicated chromosomal linkage . Depending on whether the unmapped gene and the marker were located in coupling or in repulsion, either positive or negative correlations were seen . The chromosomal location of several previously mapped genes were confirmed as a test of the method, and one previously unmapped gene, nib1, was mapped. Mol Cell Biol, 1982 Sep, 2(9), 1064 - 79 Genetic effects of methyl benzimidazole-2-yl-carbamate on Saccharomyces cerevisiae; Wood JS; The genetic effects of the mitotic inhibitor methyl benzimidazole-2-yl-carbamate (MBC) have been studied in Saccharomyces cerevisiae . MBC had little or no effect on the frequency of mutation . In some experiments MBC caused an increase in the frequency of mitotic recombination; however, this effect was small and not reproducible . The primary genetic effect of MBC was to induce mitotic chromosome loss at a high frequency . Chromosome loss occurred at equal frequencies for all chromosomes tested (13 of 16) . Cells which had lost multiple chromosomes were found more frequently than predicted if individual chromosome loss events were independent . The probability of loss for a particular chromosome increased with length of time cells were incubated with MBC . MBC treatment also increased the frequency at which polyploid cells were found . These results suggested that MBC acted to disrupt the structure or function of the mitotic spindle and cause chromosome nondisjunction. Mol Cell Biol, 1982 Sep, 2(9), 1052 - 63 Mating-defective ste mutations are suppressed by cell division cycle start mutations in Saccharomyces cerevisiae; Shuster JR; Temperature-sensitive mutants which arrest in the G1 phase of the cell cycle have been described for the yeast Saccharomyces cerevisiae . One class of these mutants (carrying cdc28, cdc36, cdc37, or cdc39) forms a shmoo morphology at restrictive temperature, characteristic of mating pheromone-arrested wild-type cells . Therefore, one hypothesis to explain the control of cell division by mating factors states that mating pheromones arrest wild-type cells by inactivating one or more of these CDC gene products . A class of mutants (carrying ste4, ste5, ste7, ste11, or ste12) which is insensitive to mating pheromone and sterile has also been described . One possible function of the STE gene products is the inactivation of the CDC gene products in the presence of a mating pheromone . A model incorporating these two hypotheses predicts that such STE gene products will not be required for mating in strains carrying an appropriate cdc lesion . This prediction was tested by assaying the mating abilities of double mutants for all of the pairwise combinations of cdc and ste mutations . Lesions in either cdc36 or cdc39 suppressed the mating defect due to ste4 and ste5 . Allele specificity was observed in the suppression of both ste4 and ste5 . The results indicate that the CDC36, CDC39, STE4, and STE5 gene products interact functionally or physically or both in the regulation of cell division mediated by the presence or absence of mating pheromones . The cdc36 and cdc39 mutations did not suppress ste7, ste11, or ste12 . Lesions in cdc28 or cdc37 did not suppress any of the ste mutations . Other models of CDC and STE gene action which predicted that some of the cdc and ste mutations would be alleles of the same locus were tested . None of the cdc mutations was allelic to the ste mutations and, therefore, these models were eliminated. J Gen Microbiol, 1982 Sep, 128 (Pt 9), 2133 - 40 Abnormalities in cell division induced by diepoxybutane in rad1-1 and rad3 mutants of Saccharomyces cerevisiae; Zaborowska D et al.; Saccharomyces cerevisiae mutants rad1-1 and rad3 differ from the wild-type and from other UV-sensitive rad mutants in their behaviour after transfer from medium containing 1,2:3,4-diepoxybutane (DEB) to DEB-free medium . In both mutants several post-treatment cell cycles proceed in the absence of cell wall separation, resulting in the formation of multicellular chains or aggregates . In this study, electron and light microscopy revealed that at least one post-treatment budding cycle is accompanied by nuclear division while subsequent cell cycles can proceed in the absence of regular nuclear cycles . At low percentage survival levels, the first post-treatment budding cycle was not delayed and was accompanied by significant incorporation of radioactivity into DNA and protein . In contrast, subsequent cell cycles were found to be accompanied by only protein synthesis and not DNA synthesis . The wild-type strain, unlike the mutants, responded to DEB treatment by a dose-dependent lag in the onset of macromolecular synthesis and cell proliferation, and after prolonged incubation in mutagen-free medium the culture consisted of single budded and unbudded cells. Mutat Res, 1982 Sep, 102(2), 123 - 36 Genetic effects of fresh cigarette smoke in Saccharomyces cerevisiae; Gairola C; Ability of fresh cigarette smoke from University of Kentucky reference cigarette 2R1 to induce gene conversion, reverse mutation and mitotic crossing-over in strain D7 of Saccharomyces cerevisiae was examined . A closed cell suspension-recycle system using 2 peristaltic pumps interconnected to a single-port reverse-phase smoking machine was developed to provide complete exposure of cells to smoke within 0.2--10 sec of its generation . The exposed cells showed a dose-dependent increase in the frequency of all the 3 genetic endpoints examined . Cell age was an important factor with younger cells being more sensitive than older . Filtration studies showed that the gas phase possessed as much as 25% of the total whole-smoke activity . Activated charcoal reduced the activity of smoke in direct proportion to its amount in the filter . Acetate filter did not appreciably alter the activity . A comparison of whole smoke from various cigarettes showed that: (1) the nicotine content of a cigarette does not affect the genetic activity of smoke; (2) burley and flue-cured tobaccos have differential activity in gene conversion and reverse mutation systems; and (3) the genetic effects of whole smoke are not peculiar to tobacco pyrolysis because similar effects are produced by smokes from lettuce and other non-tobacco cigarettes . It is concluded that the yeast D7 system can be used effectively for the quantitative evaluation of genetic effects of smoke from different cigarettes, and both whole cigarette smoke and its gas phase possess mutagenic as well as recombinogenic activity that can be modified by the use of filters. Lipids, 1982 Sep, 17(9), 662 - 5 Effect of altered sterol composition on the osmotic behavior of sphaeroplasts and mitochondria of Saccharomyces cerevisiae; McLean-Bowen CA et al.; The effect of sterols on the osmotic stability of mitochondrial and plasma membranes of yeast wild-types and mutants that are defective in ergosterol biosynthesis has been studied . Incorporation of the nonfungal sterol, cholesterol, into yeast membranes reduces membrane elasticity which is observed as an increased susceptibility to osmotic lysis . However, the wild-type and nystatin-resistant strains which were examined indicate that qualitative alterations in endogenously generated sterols do not affect resistance to swelling . Although these strains exhibit differences in membrane fluidity, which is influenced by the sterol accumulated by the organisms, the membrane stretching capacity shows no distinct dependence on sterol structure or bilayer fluidity. Mol Cell Biol, 1982 Sep, 2(9), 1025 - 32 Genetic selection for reciprocal translocation at chosen chromosomal sites in Saccharomyces cerevisiae; Potier S et al.; We have constructed viable Saccharomyces cerevisiae strains containing a reciprocal translocation between the URA2 site of chromosome X and the HIS3 site of chromosome XV . Our methodology is an extension of the method originally developed to introduce an altered cloned sequence at the chromosomal location from which the parent sequence was derived (S . Scherer and R.W . Davis, Proc . Natl . Acad . Sci . U.S.A . 76:4951-4955, 1979) . It comprises three essential steps . First, a nonreverting ura2- strain was constructed by deleting a 3.7-kilobase fragment from the coding sequence of the wild-type URA2 gene . Second, part of the coding sequence of the wild-type URA2 gene (without promotor) was inserted at the HIS3 locus of the ura2- strain . Third, after several generations of growth on uracil-supplemented medium, ura2+ colonies were selected which resulted from mitotic recombination between the nonoverlapping deletions of URA2 located on chromosomes X and XV. Eur J Biochem, 1982 Sep 1, 126(3), 617 - 22 Effect of caffeine on glucose-induced inactivation of gluconeogenetic enzymes in Saccharomyces cerevisiae . A possible role of cyclic AMP; Tortora P et al.; The mechanism of catabolite inactivation of three gluconeogenetic enzymes, fructose-1,6-bisphosphatase, cytoplasmic malate dehydrogenase and phosphoenolpyruvate carboxykinase, has been studied in the yeast Saccharomyces cerevisiae . The glucose-induced inactivation of the three enzymes is remarkably retarded by preincubation of the cells with different caffeine concentrations; however, a full conservation of activity has never been obtained, even at the highest drug concentration . Caffeine modifies the metabolic effects produced in the yeast cell by exposure to glucose . It reduces the consumption rate of glucose; changes the glycolytic intermediate pattern, giving rise to a crossover point at the level of the phosphofructokinase/fructose-bisphosphatase cycle; and increases the ATP level and the energy charge . Moreover, it substantially reduces the peak of intracellular cAMP content that immediately follows glucose entry; the magnitude of this effect is dependent on the drug concentration . The effect on the change of intracellular cAMP level appears, among all metabolic effects determined by caffeine, the only plausible one to explain the interference with catabolite inactivation of enzymes . Actually a strong negative correlation between residual activity of each of the three investigated enzymes and intracellular cAMP level has been demonstrated . The existence of a common mechanism of action of cAMP, as the mediating factor for catabolite inactivation of all three enzymes, is proposed. Biochim Biophys Acta, 1982 Aug 12, 689(3), 429 - 36 The influence of uncouplers on facilitated diffusion of sorbose in Saccharomyces cerevisiae; Van den Broek PJ et al.; Sorbose uptake in Saccharomyces cerevisiae, strain Delft 1, proceeds via mediated passive transport . In the cell sorbose is distributed in at least two compartments . Efflux studies showed that sorbose uptake in one of these compartments is not readily reversible . Uncouplers of oxidative phosphorylation inhibit both transport velocity and steady-state uptake level . It could be shown that these two effects are caused by different modes of action of the uncouplers . None of these two effects could be ascribed to changes of the electrochemical H+ gradient or of the intracellular pH . It is suggested that the inhibition of uptake velocity is caused by binding of the uncoupler to the sorbose translocator, thus lowering the transport activity . The uncoupler binding site is probably located at the intracellular fragment of the carrier . The second effect, reduction of the steady-state uptake level, is probably due to blocking of sorbose influx into the compartment that exhibits poor reversibility. Biochim Biophys Acta, 1982 Aug 6, 717(2), 355 - 68 Biochemical characterization of the OXI mutants of the yeast Saccharomyces cerevisiae; Keyhani E et al.; OXI mutants in Saccharomyces cerevisiae lack a functional cytochrome c oxidase . Wild type and OXI mutants were grown in the presence of radioactive delta-amino{14C}levulinic acid, a precursor of porphyrin and heme, and {3H}mevalonic acid, a precursor of the alkyl side-chain of heme a . SDS polyacrylamide gel electrophoresis of the delipidated mitochondria showed that delta-amino{14C}levulinic acid was distributed into three bands migrating in the regions of Mr 28 000, 13 500, and 10 000, while {3H}mevalonic acid was found in a single band with apparent Mr of 10 000 . The immunoprecipitates obtained by incubating the solubilized mitochondria of any OXI mutant with antibodies against cytochrome c oxidase, showed, after delipidation, a high specific radioactivity due to delta-amino{14C}levulinic acid and {3H}mevalonic acid . This suggested that a prophyrin a was present in all these OXI mutants . HCl fractionation confirmed the presence of porphyrin a in the apooxidase of these mutants . Atomic absorption spectra of the immunoprecipitate of cytochrome c oxidase showed that copper was not detectable in the mutant OXI IIIa which lacked subunit 1, but was present in the mutant OXI IIIb, which exhibited a minor alteration in the electrophoretic mobility of subunit 1 . In OXI I and II mutants there was a 50% reduction in the amount of copper in the immunoprecipitated cytochrome c oxidase . These observations may be interpretable as follows: (1) alterations in polypeptide biosynthesis due to the OXI mutations lead to an improper configuration of cytochrome c oxidase, so that ferrochelatase cannot transfer iron into porphyrin a; (2) subunit I is the binding site for copper, but the mutations in subunits II and III alter the binding site of one of the two copper atoms in subunit I. Mol Cell Biol, 1982 Aug, 2(8), 939 - 48 Genetic control of excision of Saccharomyces cerevisiae interstrand DNA cross-links induced by psoralen plus near-UV light; Miller RD et al.; Excision of interstrand DNA cross-links induced by 4,5',8-trimethyl psoralen plus 360-nm light was examined in wild type (RAD+) and various radiation-sensitive (rad) mutants of Saccharomyces cerevisiae known to be defective in the excision of UV light-induced pyrimidine dimers . Alkaline sucrose sedimentation of DNA after incubation of psoralen-plus-light-treated cells indicated little or no nicking of cross-linked DNA in rad1-2, rad2-5, rad3-2, rad4-4, rad10-2, and mms19-1 mutants . In the rad14-2 mutant, substantial nicking was observed but to a much lesser extent than in the RAD+ strains, whereas the rad16-1 mutant was as proficient in nicking as the RAD+ strain . Removal of cross-links was also examined in RAD+, rad3-2, and rad14-2 strains by determining the sensitivity of alkali-denatured and -neutralized DNA to hydrolysis by S1 nuclease . No cross-link removal was observed in the rad3-2 mutants, and the rad14-2 mutant was much less efficient than the RAD+ strain in removing cross-links. Mol Cell Biol, 1982 Aug, 2(8), 897 - 903 A and alpha supernatant pretreatment of Saccharomyces cerevisiae cells affects both the kinetics and efficiency of mating; Sena EP; The effects of culture supernatant treatment on subsequent matings between pretreated a and alpha Saccharomyces cerevisiae cells were studied . For each experiment, pairs of a and alpha {rho+} or {rho- rho0} cells in the logarithmic growth phase in defined minimal medium were pretreated for a total of 15 min (by exchanging their cell-free supernatants or by mixing samples of a and alpha cell cultures) and then mated in defined minimal (YNB) or enriched (YEP) liquid medium . All pretreated cells, regardless of treatment procedure, initiated cell fusion 15 to 35 min faster than did their nontreated counterparts . In all cases, pretreated cells mated 8 to 20% more efficiently than did nonpretreated ones . Regardless of the strains, the hierarchy of mating efficiency was always treated YEP greater than untreated YEP greater than treated YNB greater than untreated YNB . The cell fusion kinetics in alpha {rho+} X a {rho-} crosses were most affected by pretreatment (delta 30 to 35 min), whereas {rho+} X {rho+} crosses were least affected (delta 15 min) . These results are discussed in relation to the functions known for a and alpha pheromones . The successful pretreatment regimes were used to design new rapid and efficient techniques for mating YNB-grown log-phase cells in either YNB or YEP liquid media . These techniques can be used for small- or large-scale mating, and because of their inherent media flexibility, they have many potential applications to future studies on mating-specific or intrazygotic phenomena. Eur J Cell Biol, 1982 Aug, 28(1), 98 - 102 Ultrastructure of mitotic spindles isolated from a cell division cycle mutant of the yeast, Saccharomyces cerevisiae; King SM et al.; Mitotic spindles were isolated from a temperature-sensitive cell division cycle mutant of Saccharomyces cerevisiae arrested in medical nuclear division by incubation at 36.5 degrees C for 5 h . Cell walls were removed and the resulting sphaeroplasts lyzed on an air water interface . Spindles were collected on electron microscope grids for examination following positive or negative staining . The poles of the spindle consisted of a pair of quadrilaminar spindle pole bodies (SPBs) which measured 160 nm in diameter . The outer, cytoplasmic layer of the SPB was resolved into distinct subunits from which 1 to 3 cytoplasmic microtubules were occasionally seen to emerge . The inner, nuclear, face of the SPB was associated with two families of spindle microtubules; a bundle of 5 to 10 continuous microtubules 1.5 to 2.5 microns long with both ends associated with an SPB, and up to 17 shorter discontinuous microtubules radiating from each SPB and ending at no obvious structure. Biokhimiia, 1982 Aug, 47(8), 1401 - 8 {Mitochondrial proteinases of the yeast Saccharomyces cerevisiae: electrophoretic detection, substrate specificity and sensitivity to inhibitors}; Novikova LA et al.; The proteins of submitochondrial particles solubilized with 0.1% Triton X-100 were separated by polyacrylamide gel electrophoresis . Hydrolysis of several proteinase substrates was registered directly in the gel after completion of electrophoresis . According to the data obtained the inner mitochondrial membrane contains one or two enzymes which catalyze hydrolysis of cytochrome c as well as one or two enzymes splitting synthetic substrate of trypsin-like proteinases, e . g . N-alpha-benzoyl-L-arginine-p-nitroanilide (BAPA) and N-alpha-benzoyl-L-arginine-beta-naphthylamide (BANA) . Submitochondrial particles were shown to catalyze hydrolysis of 3H-labelled cytochrome c . This activity is suppressed by the same inhibitors as the hydrolysis of mitochondrial translation products, i . e . phenyl-methylsulfonylfluoride, p-chloromercuribenzosulfonate, leupeptin and antipain . Presumably these two processes are catalyzed by the same enzyme localized in the inner mitochondrial membrane . Physiological functions of BAPA- and BANA-hydrolyzing enzyme(s) are still unclear. Arch Microbiol, 1982 Aug, 132(2), 144 - 8 Metabolism of Saccharomyces cerevisiae envelope mannoproteins; Pastor FI et al.; By pulse and chase labeling experiments, two independent mannoprotein pools have been found associated with the Saccharomyces cerevisiae envelope . One of them probably corresponds to mannoproteins localized in the periplasmic space . These molecules showed a high turnover rate at 28 degrees C . The second pool is formed by intrinsic wall mannoproteins which are apparently stable for long periods of time, after a small initial turnover . These results suggest that at least part of the mannoproteins initially found in the periplasmic space may move into the wall . The time lag between the addition of the radioactive precursors and their incorporation in the cell envelope (20-30 min for amino acids and about 10 min for carbohydrate) indicates that protein formation and carbohydrate incorporation take place in succession . Moreover, bulk glycosylation of mannoproteins seems to occur close in time to the moment of secretion into the periplasmic space. Arch Microbiol, 1982 Aug, 132(2), 141 - 3 Isolation and characterization of a mutant of Saccharomyces cerevisiae defective in phosphoenolpyruvate carboxykinase; Perea J et al.; A mutant of Saccharomyces cerevisiae lacking phosphoenolpyruvate carboxykinase (E.C . 4.1.1.32) was isolated . The mutant did not grow on gluconeogenic sources except glycerol . The mutation was recessive and apparently affected the structural gene of the enzyme . Intracellular levels of metabolites related to the metabolic situation of the enzyme were not significantly affected after transfer of the mutant from a medium with glycerol to a medium with ethanol as carbon source . In these conditions only AMP decreased 3 to 5 times . A search for mutants affected in the other gluconeogenic enzyme, fructose 1,6 bisphosphatase, remained unsuccessful. Proc Natl Acad Sci U S A, 1982 Aug, 79(15), 4706 - 8 Ribosomal protein L3 is involved in replication or maintenance of the killer double-stranded RNA genome of Saccharomyces cerevisiae; Wickner RB et al.; Ability to secrete the K1 (or K2) toxin protein and immunity to that toxin {the K1 (or K2) killer trait} are determined by a double-stranded (ds) RNA, called M1 (or M2), whose replication and maintenance depend on at least one of the larger (L) ds RNAs and 29 chromosomal genes, called MAK genes (maintenance of killer) . The location of the MAK8 gene near TCM1 (trichodermin resistance) on the yeast map suggested the possible identity of these two genes . Of six independently isolated tcm1 mutants, five were clearly mak-, and the sixth was weakly mak- . In each case, the mak- phenotype and the trichodermin-resistant phenotypes cosegregated in meiosis and showed the expected tight linkage to pet17 . The mak- mutations in the trichodermin-resistant strains did not complement mak8-1, indicating that MAK8 and TCM1 are the same gene . The mak8-1 mutation does not make strains resistant to trichodermin, and one tcm1 mutation is only slightly mak- . Whereas tcm1 mutants lose M1 or M2 ds RNA, they do not lose L ds RNA . Because TCM1 codes for ribosomal protein L3 {Fried, H . M . & Warner, J . R . (1981) Proc . Natl . Acad . Sci, USA 78, 238--242}, we conclude that ribosomal protein L3 is involved in the replication and maintenance of M ds RNA . Mutations in cyh2 or cry1, producing resistance to cycloheximide and crytopleurine due to mutant ribosomal proteins, do not produce a mak- phenotype . In analogy with bacterial ribosome assembly mutants, yeast low-temperature-sensitive (lts) mutants may have defective ribosomes . We thus examined mutants for an effect on the killer system . An lts5 mutant, unable to grow at 5 degrees C, also has a mak- phenotype (at 30 degrees C) that cosegregates in meiosis with the lts- phenotype . Mutations in seven other lts genes do not result in the mak- phenotype. Mutat Res, 1982 Aug, 95(2-3), 213 - 24 Genetic control of budding-cell resistance in the diploid yeast Saccharomyces cerevisiae exposed to gamma-radiation; Rao BS et al.; The gamma-radiation response of stationary and budding cells of wild-type diploid strains (RAD) and radiation-sensitive strains rad2, 6, 9, 18, 50-55, 57 and rec4 was studied . As compared with the wild-type strains, mutants generally showed enhanced sensitivity in both stages of the cell cycle . Budding-cell resistance was totally absent from rad50-55 strains . Mutants rad6, 9 and 18 showed some degree of budding-cell resistance . The response of rad2 and rec4 strains was identical with that of the corresponding wild-type strains . These results suggest that the pathway dependent upon the expression of RAD50-55 loci functions more efficiently in budding cells compared with the pathway dependent on RAD2 and RAD6, 9 and 18 loci . Recombination between sister chromatids appears to play an important role in budding-cell resistance, and this process is under the control of the RAD52 repair pathway . The relationship between the repair pathways associated with budding-cell resistance and post-irradiation cellular recovery (LHR) is discussed. J Biol Chem, 1982 Jul 25, 257(14), 8177 - 82 Exonuclease II from Saccharomyces cerevisiae . An enzyme which liberates 5'-deoxyribomononucleotides from single-stranded DNA by a 5' goes to 3' mode of hydrolysis; Villadsen IS et al.; A DNase, designated Exonuclease II, has been purified 2,000-fold from whole cell extracts of bakers' yeast . It degrades single-stranded but not double-stranded DNA . The enzyme has a pH optimum around 8 and requires at least 2 mM Mg2+ for activity . It is slightly stimulated by dithiothreitol and inhibited by N-ethylmaleimide, suggesting that --SH groups are essential for activity; heparin also inhibits the activity . With 0.1 enzyme unit the Km has been determined to 4 nM of DNA ends and Vmax to 0.52 pmol of liberated nucleotides per min . The Mr is around 120,000 . The enzyme does not degrade circular single-stranded M13 DNA, whereas linearized M13 DNA is degraded . The products are 5'-deoxyribomononucleotides exclusively . Using 5'-end labeled and 3'-end labeled DNA fragments as substrates, partially degraded DNA is only detectable in the latter case, showing that the exonuclease solely attacks DNA from the 5'-end . This distinguishes Exonuclease II from other exonucleases degrading DNA from the 5'-end, since they all either produce a mixture of 5'-mono- and oligonucleotides or 3'-mononucleotides . Analysis of 3'-end labeled fragments after incubation shows that the rate of exonucleolytic cleavage was dependent on the DNA sequence at the 5'-end. J Biol Chem, 1982 Jul 25, 257(14), 8405 - 11 Alterations of transcription during heat shock of Saccharomyces cerevisiae; Finkelstein DB et al.; The pattern of polyadenylated RNA of the yeast Saccharomyces cerevisiae changes dramatically upon heat shock . By in vitro translation, we have demonstrated that a 2.9-kilobase heat shock RNA encodes the Mr = 90,000 yeast heat shock protein . Heat shock-responsive genes have been isolated by differential plaque filter hybridization of a recombinant library of yeast DNA inserted in the vector lambda Charon 4 . The putative yeast gene products of a number of these recombinants molecules has been determined by in vitro translation of hybrid-selected RNA . We have used one of these hybrid phages (lambda Yhsil) to demonstrate that the heat shock-induced alteration in the level of the 2.9-kilobase polyadenylated RNA which encodes the Mr = 90,000 yeast heat shock protein is regulated at the level of transcription. Biochim Biophys Acta, 1982 Jul 14, 689(1), 38 - 44 Turnover of protein components of the plasma membrane of Saccharomyces cerevisiae; Herrero E et al.; The peptide composition of plasma membrane in Saccharomyces cerevisiae cells growing at different temperatures between 18 and 38 degrees C was studied using SDS-polyacrylamide gel electrophoresis . Stability of the proteins, both qualitative and quantitative, was observed at the tested temperatures . Treatment for 2 h with cycloheximide decreased by about 50% the amount of a 80 kDa membrane peptide at 18, 23, 28 and 33 degrees C, with no other apparent effects . At 38 degrees C the 80 kDa peptide was not affected by the presence of the drug . Addition of tunicamycin to cultures at concentrations partially inhibitory to growth caused a large accumulation of the 80 kDa peptide in the plasma membrane, which cycloheximide did not modify . Pulse-chase experiments indicated a low rate of turnover of total plasma membranes in cells growing at 18 and 28 degrees C . In contrast, at 38 degrees C about 50% of the radioactivity in plasma membranes disappeared after a 2 h chase . The 80 kDa protein band was the only one with significant differential decay. J Bacteriol, 1982 Jul, 151(1), 311 - 27 Quantitative analysis of the heat shock response of Saccharomyces cerevisiae; Miller MJ et al.; Transient protein synthesis in Saccharomyces cerevisiae, after shift from 21-23 degrees C to 37 degrees C, was quantitatively analyzed . Pulse-labeled proteins were separated by two-dimensional gel electrophoresis, and autoradiograms of the gels were analyzed by a recently described method involving a computer-coupled film scanning system . In this way, the rate of incorporation of L-{35S}methionine into approximately 500 proteins was followed . The synthesis of more than 80 of these proteins was transiently induced at 37 degrees C, with about 20 being classified as major heat shock proteins (defined as those whose rate of labeling was increased at least eightfold at some time during the response) . The synthesis of more than 300 of the proteins was transiently repressed at 37 degrees C, and several general temporal patterns of repression could be distinguished . The influence of temperature-sensitive mutations affecting RNA synthesis and transport on the heat shock response was also examined . A protein whose induction in response to heat shock has a post-transcriptional component could be identified . As previously pointed out, the heat shock repression of certain proteins is so rapid that it also must involve post-transcriptional effects. Mol Cell Biol, 1982 Jul, 2(7), 731 - 6 Genetic and biochemical study of threonine-overproducing mutants of Saccharomyces cerevisiae; Delgado MA et al.; Three threonine-overproducing mutants were obtained as prototrophic revertants of a hom3 mutant strain of Saccharomyces cerevisiae . The gene HOM3 codes for aspartokinase (aspartate kinase; EC 2.7.2.4), the first enzyme of the threonine-methionine biosynthetic route, which is subjected to feedback inhibition by threonine . Enzymatic studies indicated that aspartokinase from the revertants has lost the feedback inhibition, resulting in overproduction of threonine . These revertants also bore one or two additional mutations, named tex1-1 and tex2-1, which alone or jointly made possible the excretion of the threonine accumulated . The effect of these two genes on excretion is potentiated by excess inositol in the medium. Proc Natl Acad Sci U S A, 1982 Jul, 79(14), 4243 - 7 Purification of the cdc8 protein of Saccharomyces cerevisiae by complementation in an aphidicolin-sensitive in vitro DNA replication system; Kuo CL et al.; DNA synthesis in vitro in Brij-treated Saccharomyces cerevisiae requires the product of the CDC8 gene (Hereford, L . M . & Hartwell, L . H . (1971) Nature (London) New Biol . 234, 171-172) . Extracts of wild-type A364a yeast restore DNA synthesis in Brij-treated cdc8, a mutant containing a thermolabile cdc8 gene product . This constitutes a complementation assay by which the cdc8 gene product can be monitored during purification . A heat-stable protein responsible for this complementation has been partially purified from both wild-type A364a cells and from a cdc8 temperature-sensitive mutant . The complementation activity from the mutant is thermolabile when compared to the wild-type activity, indicating that CDC8 is the structural gene for the protein. J Antibiot (Tokyo), 1982 Jul, 35(7), 875 - 81 Inhibition of protein synthesis in Saccharomyces cerevisiae by the 12,13-epoxytrichothecenes trichodermol, diacetoxyscirpenol and verrucarin A . Reversibility of the effects; Hernandez F et al.; Inhibition of protein synthesis by trichodermol, diacetoxyscirpenol and verrucarin A in cells and spheroplasts of Saccharomyces cerevisiae was investigated . Inhibition was reversible for trichodermol and diacetoxyscirpenol, both drugs being removed from their target site(s) by washing, but was reversible for verrucarin A . These results are interpreted in relation to variations in chemical structure between these trichothecenes. Genetics, 1982 Jul-Aug, 101(3-4), 369 - 404 Recombination between genes located on nonhomologous chromosomes in Saccharomyces cerevisiae; Mikus MD et al.; We constructed strains of Saccharomyces cerevisiae that contained two different mutant alleles of either the leu2 gene or the ura3 gene . These repeated genes were located on chromosomes V and XII and the two leu2- alleles were located on chromosomes III and XII . Genetic interactions between the two mutant copies of a gene were detected by the generation of either Leu+ or Ura+ revertants . Both spontaneous and ultraviolet irradiation-induced revertants were examined . By genetic and physical analysis, we have shown that Leu+ or Ura+ revertants can arise by a variety of different genetic interactions . The most common type of genetic interaction is the nonreciprocal transfer of information from one repeat to the other . We also detected reciprocal recombination between repeated genes, resulting in reciprocally translocated chromosomes. Genetics, 1982 Jul-Aug, 101(3-4), 345 - 67 Frameshift suppression in Saccharomyces cerevisiae . IV . New suppressors among spontaneous co-revertants of the Group II his4-206 and leu 2-3 frameshift mutations; Gaber RF et al.; ICR-induced frameshift mutations at the his4 locus in Saccharomyces cerevisiae have been classified into several groups on the basis of their reversion and suppression properties . One group of externally suppressible his4 mutations, designated Group II, have been shown to contain +1 G:C insertions in glycine codons and are suppressed by any one of five suppressor mutations described previously (SUF1, SUF3, SUF4, SUF5, and SUF6) . The suppressor genes are believed to encode glycine tRNAs containing four base anticodons.--An analysis of spontaneous co-revertants of the Group II frameshift mutation his4-206 and leu2-3 has revealed the existence of eleven new Group II-specific suppressor genes (SUF15 through SUF25) . The locations of the new suppressor loci on the yeast genetic map have been determined.--By comparing the ability or inability of Group II-specific suppressors mapping at 16 different Group II his4 mutations, two subclasses of suppressors have been defined . One subclass suppresses his4-38 and his4-519, which contain the altered four base mRNA codons 5'-GGGU-3' and 5'-GGGG-3', respectively . The other subclass suppresses his4-38, but fails to suppress his4-519 . The mechanism of tRNA-mediated frameshift suppression and the molecular basis for this division of the suppressors into two subclasses is discussed. Mutat Res, 1982 Jul-Aug, 102(1), 59 - 69 Genetic activity in Saccharomyces cerevisiae and thin-layer chromatographic comparisons of medical grades of pyrvinium pamoate and monopyrvinium salts; Mehta RD et al.; The pamoate, chloride, and iodide salts of pyrvinium, a cyanine dye with anthelmintic properties, were studied in a diploid mitotic recombination and gene conversion assay system (strain D5 of Saccharomyces cerevisiae) and a haploid yeast reversion assay (strain XV185-14C) . With the use of a thin-layer chromatographic (TLC) detection technique, samples of pyrvinium pamoate from several sources were found to contain different numbers and quantities of impurities . All samples of pyrvinium pamoate and the monopyrvinium salts were recombinogenic in strain D5 and mutagenic in strain XV185-14C; the degree of genetic activity varied among the tested medical grades of pyrvinium pamoate . Monopotassium pamoate was found to be genetically inactive in both strains . Light-catalyzed degradation did not enhance the genetic activity of pyrvinium in either of the yeast strains; the degraded samples were not mutagenic. J Bacteriol, 1982 Jul, 151(1), 334 - 42 Effect of inositol starvation on the in vitro syntheses of mannan and N-acetylglucosaminylpyrophosphoryldolichol in Saccharomyces cerevisiae; Hanson BA et al.; An early consequence of starvation for inositol in yeast is inhibition of synthesis of the major cell wall components mannan and glucan . In looking for the mechanism of this inhibition, we found that the activity of the enzyme catalyzing the synthesis of N-acetylglucosaminylpyrophosphoryldolichol was diminished in particular membrane preparations from cells starved for inositol . This loss of reactivity was observed under a variety of in vitro assay conditions and could be restored by the addition of phosphatidylinositol but not by other phosphoinositol-containing sphingolipids known to occur in yeast . When assayed in the presence of high concentrations of Triton X-100, enzyme preparations from both control and inositol-starved cells required phosphatidylinositol for maximal activity . Since this enzyme catalyzed an early step in the synthesis of mannan that is N-linked to protein, a reasonable hypothesis is that inhibition of mannan synthesis in inositol-starved cells results from the depletion of the necessary cofactor phosphatidylinositol. Mol Cell Biol, 1982 Jul, 2(7), 800 - 4 Post-translational processing of urea amidolyase in Saccharomyces cerevisiae; Sumrada RA et al.; Urea amidolyase catalyzes the two reactions (urea carboxylase and a allophanate hydrolase) associated with urea degradation in Saccharomyces cerevisiae . Past work has shown that both reactions are catalyzed by a 204-kilodalton, multifunctional protein . In view of these observations, it was surprising to find that on induction at 22 degrees C, approximately 2 to 6 min elapsed between the appearance of allophanate hydrolase and urea carboxylase activities . In search of an explanation for this apparent paradox, we determined whether or not a detectable period of time elapsed between the appearance of allophanate hydrolase activity and activation of the urea carboxylase domain by the addition of biotin . We found that a significant portion of the protein produced immediately after the onset of induction lacked the prosthetic group . A steady-state level of biotin-free enzyme was reached 16 min after induction and persisted indefinitely thereafter . These data are consistent with the suggestion that sequential induction of allophanate hydrolase and urea carboxylase activities results from the time required to covalently bind biotin to the latter domain of the protein. J Bacteriol, 1982 Jul, 151(1), 29 - 35 Nitrogen catabolite repression in a glutamate auxotroph of Saccharomyces cerevisiae; Kang L et al.; The biosynthesis of asparaginase II in Saccharomyces cerevisiae is subject to nitrogen catabolite repression . In the present study we examined the physiological effects of glutamate auxotrophy on cellular metabolism and on the nitrogen catabolite repression of asparaginase II . Glutamate auxotrophic cells, incubated without a glutamate supplement, had a diminished internal pool of alpha-ketoglutarate and a concomitant inability to equilibrate ammonium ion with alpha-amino nitrogen . In the glutamate auxotroph, asparaginase II biosynthesis exhibited a decreased sensitivity to nitrogen catabolite repression by ammonium ion but normal sensitivity to nitrogen catabolite repression by all amino acids tested. Biochim Biophys Acta, 1982 Jun 11, 711(3), 403 - 10 Purification and properties of a phospholipid acyl hydrolase from plasma membranes of Saccharomyces cerevisiae; Witt W et al.; The properties of a phospholipid acyl hydrolase bound to yeast plasma membranes are described in detail . The enzyme is capable of splitting all phospholipids which can be extracted from yeast cells . The specific activity with lysophosphatidylcholine as substrate was much higher than with phosphatidylcholine . With dipalmitoyl phosphatidylcholine as substrate a broad pH optimum was measured between pH 3.0 and 4.5 . The membrane-bound enzyme was activated strongly by the anionic detergents SDS, deoxycholate and, to a lesser extent, by cholate . The uncharged detergent Triton X-100 and the zwitterionic detergent SB12 exerted an only slightly activating effect . KCl, NaCl, MgCl2, and CaCl2 were inhibitory in the presence of glycine/acetic acid buffer at pH 4.0 . THe enzyme was solubilized by cholate or by SB12 in an active form from the plasma membrane and purified by acetone and (NH4)2SO4 precipitation or gel filtration with Sephadex G-200 . THe phospholipid acyl hydrolase was identified as a glycoprotein with an apparent molecular weight of 145,000 by SDS slab gel electrophoresis. J Biol Chem, 1982 Jun 10, 257(11), 6268 - 74 Assembly of the mitochondrial membrane system . Processing of the apocytochrome b precursor RNAs in Saccharomyces cerevisiae D273-10B; Bonitz SG et al.; The DNA sequence of the apocytochrome b gene in Saccharomyces cerevisiae D273-10B contains two intervening sequences (Nobrega, F . G., and Tzagoloff, A . (1980) J . Biol . Chem . 255, 9828-9837) . The exon-intron boundaries of the gene have been determined in this study from the sequence of the DNA which was copied from the mRNA . A protein of 385 amino acid residues is predicted from the 1155-nucleotide long coding regions . Northern blot analysis of total mitochondrial RNA, probed with restriction fragments from both exon and intron regions of the gene, reveals a 4.3-kilobase (kb) transcript containing both introns and two partially spliced intermediates, one (2.9 kb) lacking the first intron and the other (3.6 kb) lacking the second intron . The most abundant transcript (2.1 kb) hybridizes only to exon probes and is presumed to the fully spliced mRNA . S1 nuclease mapping of the purified mRNA indicates existence of two separate RNAs with identical 3' termini but differing by approximately 217 nucleotides at their 5' ends . The larger transcript has a 950-nucleotide nontranslated leader . Analyses of the RNA species present in various rho- and mit- mutants indicate that: 1) exon mutants process both introns, albeit not as efficiently as wild type, 2) intron mutants blocked in the excision of the first or second intron are capable of processing the alternate intron, suggesting a non-obligatory order of excision of the two intervening sequences, and 3) excision of the second intron occurs in rho- mutants and therefore does not require a mitochondrial translation product. J Biol Chem, 1982 Jun 10, 257(11), 6581 - 7 Characterization of transcripts from the Var1 region on mitochondrial DNA of Saccharomyces cerevisiae; Farrelly F et al.; We have identified transcripts with sequence homology to the var1 region on yeast mtDNA . In wild type, and in cytoplasmic petite strains retaining the var1 region, we detect four RNA species, 19 S, 16 S, 14 S, and 13 S, which hybridize to var1 DNA probes . The 16 S RNA is by far the most abundant of these RNAs in wild type cells . We also observe hybridization of the 15 S rRNA and a 10 S RNA species to var1 DNA probes . This hybridization is most likely due to the presence in these RNAs of a GC-rich cluster which has near perfect sequence homology to a GC-rich cluster in the var1 region . We find that the 16 S RNA, estimated to be 2000 to 2100 nucleotides long, varies in size in direct correspondence with the size of var1 polypeptide; it is about 100 nucleotides longer in strains with the var1 (44,000) allele than in strains with var1 (40,000) . The amount of the 16 S RNA also varies in correspondence with the amount of var1 polypeptide made; it is increased in an oxi-3 mit- strain (CAD245) which makes about 10 times more var1 protein than wild type, and is barely detected in PZ200, a strain with very low levels of mitochondrial protein synthesis harboring two mutations within var1 . We have purified the 16 S RNA following chromatography over oligo(dT) cellulose columns . When the RNA is end-labeled and hybridized to a HincII digest of wild type mtDNA, we observe hybridization only to the fragment containing the entire var1 region, HincII fragment 10. Biochemistry, 1982 Jun 8, 21(12), 2957 - 63 In vivo phosphorus-31 nuclear magnetic resonance saturation transfer studies of adenosinetriphosphatase kinetics in Saccharomyces cerevisiae; Alger JR et al.; Phosphorus-31 saturation transfer NMR techniques have been employed to measure the unidirectional Pi consumption rate by respiration competent suspensions of the yeast Saccharomyces cerevisiae while the levels of ATP, ADP, and Pi are constant . These experiments are performed by saturating the ATP gamma phosphate resonance and observing the changes in the Pi resonance intensity while the yeast are respiring on endogenous substrates . The unidirectional Pi consumption rate is 3.5 +/- mumol s-1 (g of wet cells)-1 . The rate is reduced 10-fold upon addition of oligomycin (80 micrograms/ML), suggesting that at least 90% of the Pi consumption activity is due to the mitochondrial F1-F0 ATPase . We have not been able to conclusively assign the remaining 10% . When the yeast are glycolyzing anaerobically, the unidirectional Pi consumption rate was 1.0 +/- 0.2 mumol s-1 (g of wet cells)-1 . At most, 80% of this is due to Pi consumption by the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase leaving a residual activity of at least 0.2 mumol s-1 (g of wet cells)-1 . Thus the activity in the oligomycin-inhibited cells under respiratory conditions and the nonglycolytic activity in anaerobic cells are equal to within the experimental errors . Furthermore the unidirectional rate of Pi consumption during anaerobic glycolysis is insensitive to oligomycin . These data suggest that the mitochondrial adenosinetriphosphatase is not turning over during anaerobic glycolysis . Possible explanations for this inhibition are discussed. Biokhimiia, 1982 Jun, 47(6), 962 - 70 {Inhibiting effect of concanavalin A on certain biosynthetic processes in spheroplasts of the yeast Saccharomyces cerevisiae}; Riazanova LP et al.; The effect of concanavalin A on biosynthesis of nucleic acids, proteins, structural polysaccharides and glycoproteins of the yeast cell membrane and of enzymes having different localization in the cell as well as on other processes occurring in spheroplasts of the yeasts Saccharomyces cerevisiae IBPhM-350 and CCY 21-4-13 were studied . In both yeast strains lectin strongly inhibited total protein synthesis and produced a weaker inhibiting effect on DNA and RNA synthesis . This was accompanied by a decrease of the activity of the majority of already known enzymes (acid phosphatase, invertase, alpha-glucosidase, polyphosphatase, pyrophosphatase, ATPase) and glucose consumption . In addition concanavalin A inhibited the synthesis of structural components of the yeast cell membrane, i.e . mannane and glucane . The data obtained suggest that lectin (50 microgram/ml or higher) has a toxic effect on yeast spheroplasts (or protoplasts). Arch Microbiol, 1982 Jun, 131(4), 298 - 301 Localization of trehalase in vacuoles and of trehalose in the cytosol of yeast (Saccharomyces cerevisiae); Keller F et al.; Protoplasts of Saccharomyces cerevisiae synthesized and degraded trehalose when they were incubated in a medium containing traces of glucose and acetate . Such protoplasts were gently lyzed by the polybase method and a particulate and soluble fraction was prepared . Trehalose was found in the soluble fraction and the trehalase activity mostly in the particulate fraction which also contained the vacuoles besides other cell organelles . Upon purification of the vacuoles, by density gradient centrifugation, the specific activity of trehalase increased parallel to the specific content of vacuolar markers . This indicates that trehalose is located in the cytosol and trehalase in the vacuole . It is suggested that trehalose, in addition to its role as a reserve may also function as a protective agent to maintain the cytosolic structure under conditions of stress. Proc Natl Acad Sci U S A, 1982 Jun, 79(11), 3565 - 9 Nucleotide sequence of the SUF2 frameshift suppressor gene of Saccharomyces cerevisiae; Cummins CM et al.; To elucidate the molecular mechanism of frameshift suppression by the SUF2 gene of yeast, the sequences of DNA fragments carrying the SUF2-1 and suf2+ alleles of the gene and surrounding regions have been determined . Comparison of the suppressor and wild-type sequences indicates that the SUF2 gene product is a proline tRNA . Disregarding possible base modifications, we find that the wild-type suf2+ anticodon of the tRNA inferred from the DNA sequence is 3'-GGA-5' . The SUF2-1 mutation represents the insertion of a G-C base pair at a position in the gene that corresponds to the anticodon loop of the tRNA . Replacement of the wild-type suf2+ anticodon by a 3'-GGGA-5' fourbase anticodon enables the SUF2-1 tRNA to suppress the 5'-CCCU-3' four-base codons generated as the result of the his4-712 and his4-713 frameshift mutations . This nontriplet codon-anticodon interaction restores the correct reading frame and allows synthesis of a functional his4 protein. J Bioenerg Biomembr, 1982 Jun, 14(3), 191 - 205 Transmembrane ferricyanide reduction by cells of the yeast Saccharomyces cerevisiae; Crane FL et al.; Both respiratory-competent and respiratory-deficient yeast cells reduce external ferricyanide . The reduction is stimulated by ethanol and inhibited by the alcohol dehydrogenase inhibitor, pyrazole . The reduction of ferricyanide is not inhibited by inhibitors of mitochondrial or microsomal ferricyanide reduction . Cells in exponential-phase growth show a much higher rate of ferricyanide reduction . The reduction of ferricyanide is accompanied by increased release of protons by the yeast cells . We propose that the ferricyanide reduction is carried out by a transmembrane NADH dehydrogenase. J Bioenerg Biomembr, 1982 Jun, 14(3), 159 - 69 The reconstitution of oxidative phosphorylation in mitochondria isolated from a ubiquinone-deficient mutant of Saccharomyces cerevisiae; De Santis A et al.; Mitochondria, isolated from the ubiquinone-deficient nuclear mutant of Saccharomyces cerevisiae E3-24, are practically unable to oxidize exogenous substrates . Respiratory activity, coupled to ATP synthesis, can, however, be reconstituted by the simple addition of ethanolic solutions of ubiquinones . A minimal length of the isoprenoid side chain (greater than or equal to 3) was required for the restoration . Saturation of the reconstitution required a large amount of exogeneous ubiquinone, in excess over the normal content present in the mitochondria of the wild type strain . A similar pattern of reconstituted activities could be also obtained using sonicated inverted particles . Mitochondria and sonicated particles are also able to carry out a dye-mediated electron flow coupled to ATP synthesis in the absence of added ubiquinone, using ascorbate or succinate as electron donor . This demonstrates that the energy conserving mechanism at the third coupling site of the respiratory chain is fully independent of the presence of the large mobile pool of ubiquinone in the membrane. J Gen Microbiol, 1982 Jun, 128(Pt 6), 1309 - 17 Genetic block of outer plaque morphogenesis at the second meiotic division in an hfd1-1 mutant of Saccharomyces cerevisiae; Okamoto S et al.; An hfd1-1 mutant of Saccharomyces cerevisiae, SOS4, characterized by predominant production of two-spored asci at 29 degrees C, undergoes normal meiotic nuclear divisions and produces four haploid nuclei, but only two non-sister nuclei among them are incorporated into mature ascospores . Spindle pole bodies and prospore wall membranes at the second meiotic division at 29 degrees C were observed in this mutant by electron microscopy . The spindle pole body at one pole of each spindle had a normal outer plaque which was larger than the inner plaque . At the other pole, the outer plaque was entirely absent and a normal prospore wall membrane was not detected . It was concluded that at 29 degrees C the hfd1-1 mutation blocks the morphogenesis of outer plaques and prospore wall membranes at the two non-sister poles in the second meiotic division, and consequently only non-sister nuclei in the resulting meiotic cell are incorporated into ascospores. Can J Biochem, 1982 Jun, 60(6), 659 - 67 Electroimmunochemical analysis of plasma membrane vesicles from Saccharomyces cerevisiae; Gerlach JH et al.; Plasma membrane vesicles of Saccharomyces cerevisiae were extracted with 1% (w/v) Triton X-100 and the solubilized proteins examined by crossed immunoelectrophoresis using rabbit antibodies against the vesicles . Solubilization was shown to be nonselective and 23 immunoprecipitates were observed reproducibly . Four glycoproteins were identified by interaction with concanavalin A and lentil lectin, either immobilized on agarose beads in an intermediate gel or incorporated in the free form in the first dimension gel . One glycoprotein was stainable by the periodic acid--Schiff procedure . None of the glycoproteins had their origin in the cell wall . Five amphiphilic proteins were identified on the basis of charge-shift and hydrophobic interaction crossed immunoelectrophoresis as well as {14C}Triton X-100 and Sudan black B binding . Three of the amphiphilic proteins were also glycoproteins . Based on the carbohydrate content and amphiphilic properties of the proteins, purification schemes using concanavalin A-Sepharose and phenyl-Sepharose were proposed . Trial separations using 1-mL columns were monitored by fused rocket and crossed immunoelectrophoresis. J Biol Chem, 1982 May 25, 257(10), 5568 - 75 Biosynthetic control of the natural abundance of carbon 13 at specific positions within fatty acids in Saccharomyces cerevisiae . Isotopic fractionation in lipid synthesis as evidence for peroxisomal regulation; Monson KD et al.; Measurements of the natural abundance of 13C at C-1, C-9, and C-10 in fatty acids synthesized by Saccharomyces cerevisiae grown aerobically at 30 degrees C show that alkyl chain positions derived from the carboxyl group of the acetate precursor must be enriched in 13C by 2.5 +/- 0.6 parts per thousand while those derived from the methyl group in acetate must be depleted in 13C by an equal amount . Selective depletions of 13C observed at the C-9 and C-10 positions of palmitoleate and oleate require that (i) the carbon kinetic isotope effect associated with the action of desaturase at C-9 must be between 1.2 and 1.6% in vivo, (ii) at C-10 the effect must be between 0.9 and 1.3%, and (iii) less than 20% of the C18 carbon skeletons synthesized are preserved within the cell, the remainder apparently being degraded . It is shown that the novo synthesis (i.e . by fatty acid synthetase) is responsible for the production of more than 95% of the supply of 18-carbon acyl groups, the remainder being provided by all other elongation pathways . In an ancillary study designed to test the accuracy and generality of these results, it was observed that still larger specific depletions occurred at olefinic carbon position in fatty acids from soybeans, thus suggesting that the degradation of substantial quantities of C18 carbon skeletons may be a widespread feature of fatty acid metabolism in eukaryotes . It is suggested that the required degradation is associated with the action of peroxisomes. J Biol Chem, 1982 May 25, 257(10), 5730 - 7 Effects of mannoprotein mutations on Saccharomyces cerevisiae core oligosaccharide structure; Cohen RE et al.; By the combined actions of an endo-alpha-1 leads to 6-mannanase and an endo-beta-N-acetylglucosaminidase, the core oligosaccharides can be released from Saccharomyces cerevisiae X2180 mnn2 mannoproteins . The effects of various mannoprotein mutations were evaluated by structural comparison of these core oligosaccharides with those prepared from double mutant strains with the genotypes mnn1 mnn2, mnn2 mnn3, mnn2 mnn4, and mnn2 mnn5 . The results indicate that only the mnn1 lesion has a major effect on the mannoprotein core structure . Whereas the mnn2 mannoprotein yields a core composed of 6 fragments that differ in size from each other by single mannose units, only the two smallest species predominate in the mnn1 mnn2 preparation . This change is correlated with a loss of terminal alpha 1 leads to 3-mannosyl residues, an effect on the mnn1 lesion that is found also in the polysaccharide outer chain and hydroxyamino acid-linked mannooligosaccharides . The mnn3 and mnn5 mutations also had slight effects on the core size, but clear differences in linkage composition were not apparent . The results suggest that core oligosaccharides have an average composition of Man11GlcNAc, whereas Man9GlcNAc is the major oligosaccharide in strains containing the mnn1 defect . These values are 2 to 3 sugars less than those estimated previously (Nakajima, T., and Ballou, C . E . (1975) Biochem . Biophys . Res . Commun . 66, 870-879) . Detailed analysis of the major core oligosaccharide from the mnn1 mnn2 mutant revealed that the two mannoses in alpha 1 leads to 3 linkage to the backbone were adjacent to each other and that the oligosacccharide is nearly identical with one isolated from chinese hamster ovary cell membranes (Li, E., and Kornfeld, S . (1979) J . Biol . Chem . 254, 1600-1605) . This finding provides strong evidence for the evolutionary conservation of this structural feature of the high mannose core oligosaccharides. Mol Cell Biol, 1982 May, 2(5), 571 - 77 A suppressor of temperature-sensitive rna mutations that affect mRNA metabolism in Saccharomyces cerevisiae; Pearson NJ et al.; We have isolated a dominant suppressor of rna mutation (SRN1) that relieves the temperature-sensitive inhibition of mRNA synthesis of ribosomal protein genes in the yeast Saccharomyces cerevisiae . The suppressor was selected for its ability to alleviate simultaneously the temperature-sensitive growth phenotypes of rna2 and rna6 . Several independently isolated suppressors appeared to be recessive lethal mutations . One suppressor, SRN1, was recovered as viable in haploid strains . SRN1 can suppress rna2, rna3, rna4, rna5, rna6, and rna8 singly or in pairs, although some combinations of rna mutations are less well suppressed than others . The suppressor allows strains with rna mutations to grow at 34 degrees C but is unable to suppress at 37 degrees C; however, SRN1 does not, by itself, prevent growth at 37 degrees C . In addition, SRN1 suppresses the rna1 mutation which affects general mRNA levels and also leads to the accumulation of precursor tRNA for those tRNAs that have intervening sequences . SRN1 can suppress the rna1 mutation as well as the rna1 rna2 double mutation at 34 degrees C . The suppressor does not affect the temperature-sensitive growth of two unrelated temperature-sensitive mutations, cdc4 and cdc7. Mol Cell Biol, 1982 May, 2(5), 490 - 7 Endogenous read-through of a UGA termination codon in a Saccharomyces cerevisiae cell-free system: evidence for involvement of both a mitochondrial and a nuclear tRNA; Tuite MF et al.; Globin mRNA, translated in a Saccharomyces cerevisiae cell-free protein synthesizing system prepared from a {psi+ rho+} strain, primarily directed the synthesis of alpha- and beta-globin . A third globin mRNA-specific polypeptide was also synthesized, representing approximately 10% of the total translation products . This polypeptide (beta') was synthesized by translational read-through of the beta- globin mRNA UGA terminator and was mediated primarily by an endogenous tRNA coded for by the mitochondria . This mitochondrial tRNA, when charged, could be preferentially bound, in high salt, to benzoylated DEAE-cellulose, a characteristic of a tRNATrp . The synthesis of beta- mediated by this mitochondrial tRNATrp was significantly reduced when the translation system was prepared from an isogenic {psi-} strain . Evidence for a nuclear-coded tRNA, also able to suppress the beta-globin mRNA UGA terminator in {psi+} but not {psi-} lysates, was also obtained . The presence of these endogenous UGA suppressor activities in the yeast cell-free system should allow successful in vitro translation of mitochondrial mRNAs. Antonie Van Leeuwenhoek, 1982 May, 48(2), 145 - 57 Mutants of Saccharomyces cerevisiae cell division cycle defective in cytokinesis . Biosynthesis of the cell wall and morphology; Dominguez A et al.; The four temperature-sensitive mutants of Saccharomyces cerevisiae in the cell division cycle defective in cytokinesis (cdc, 3, 10, 11 and 12), have been analyzed with respect to the biosynthesis of the cell wall polymers . After 3 hours of incubation at the non-permissive temperature (37 degrees C) these strains stop growing . The synthesis of glucan, mannan and chitin (wall polymers) level off in a similar time, but glucan, mannan and chitin synthases remained active for at least 4 hours . If the mutants are analyzed by transmission and scanning electron microscopy different pictures emerge . Two of the mutants cdc 10 and cdc 12, after 3 hours of incubation at 37 degrees C present apparently normal cytoplasms and cell wall surfaces with multiple elongated buds . The other two mutants, cdc 3 and cdc 11, present a completely disarranged cytoplasmic content and damage at the level of the plasma membrane is evident . These and other observations, suggest that between the execution points of cdc 3 (0.27) and cdc 10 (0.58), essential processes in the assembly of cell membrane occur. J Bacteriol, 1982 May, 150(2), 969 - 72 Evidence that alpha-isopropylmalate synthase of Saccharomyces cerevisiae is under the "general" control of amino acid biosynthesis; Hsu YP et al.; The specific activity and the immunoreactive amount of alpha-isopropylmalate synthase were more than three times above wild-type values in a Saccharomyces cerevisiae mutant (cdr1) with constitutively derepressed levels of enzymes known to be under the "general" control of amino acid biosynthesis . The specific activity was also higher in lysine- and arginine-leaky strains when these were grown under limiting conditions, and in wild-type cells grown in the presence of 5-methyltryptophan . A low specific activity was found in a mutant (ndr1) unable to derepress enzymes of the general control system . Neither isopropylmalate isomerase nor beta-isopropylmalate dehydrogenase responded to general control signals. J Bacteriol, 1982 May, 150(2), 890 - 9 Repression and induction of flocculation interactions in Saccharomyces cerevisiae; Miki BL et al.; The biological control of flocculation interactions by factors related to growth under different conditions of aeration was documented with a new assay for flocculence . The degree of flocculence expressed in a genetically defined Saccharomyces cerevisiae strain (FLO1/FLO1 ade1/ade1) remained constant during aerobic growth but varied with aeration . Flocculence was repressed in anaerobically growing cells but was induced in stationary cells or cells returned to aerobic growth . Repression was correlated with the selective inactivation of cell surface lectin-like components . The changes in flocculence were accompanied by changes in 16 extractable proteins separated by electrophoresis; however, a clear correlation between specific protein bands and flocculence could not be established . The study clearly demonstrated that the phenotypic expression of FLO1 could be reproducibly manipulated for experimental purposes by aeration alone. J Bacteriol, 1982 May, 150(2), 878 - 89 Possible mechanism for flocculation interactions governed by gene FLO1 in Saccharomyces cerevisiae; Miki BL et al.; A model is proposed for the mechanism of flocculation interactions in yeasts in which flocculent cells have a recognition factor which attaches to alpha-mannan sites on other cells . This factor may be governed by the expression of the single, dominant gene FLO1 . Isogenic strains of Saccharomyces cerevisiae, differing only at FLO1 and the marker genes ade1 and trp1, were developed to examine the components involved in flocculene . Electron microscopy and concanavalin Aferritin labeling of aggregated cells showed that extensive and intense interactions between cell wall mannan layers mediated cell aggregation . The components of the mannan layer essential for flocculence were Ca2+ ions, alpha-mannan carbohydrates, and proteins . By studying the divalent cation dependence at various pH values and in the presence of competing monovalent cations, flocculation was found to be Ca2+ dependent; however, Mg2+ and Mn2+ ions substituted for Ca2+ under certain conditions . Reversible inhibition of flocculation by concanavalin A and succinylated concanavalin A implicated alpha-branched mannan carbohydrates as one essential component which alone did not determine the strain specificity of flocculence, since nonflocculent strains interacted with and competed for binding sites on flocculent cells . FLO1 may govern the expression of a proteinaceous, lectin-like activity, firmly associated with the cell walls of flocculent cells, which bind to the alpha-mannan carbohydrates of adjoining cells . It was selectively and irreversibly inhibited by proteolysis and reduction of disulfide bonds . The potential of this system as a model for the genetic and biochemical control of cell-cell interactions is discussed. J Bacteriol, 1982 May, 150(2), 545 - 51 Co-curing of plasmids affecting killer double-stranded RNAs of Saccharomyces cerevisiae: {HOK}, {NEX}, and the abundance of L are related and further evidence that M1 requires L; Sommer SS et al.; We describe two sets of plasmid-plasmid interactions in the yeast Saccharomyces cerevisiae . {HOK}, {EXL}, {NEX}, and {KIL-k1} are genetically defined plasmids, and M1 and L are biochemically defined double-stranded RNA plasmids . We show that (i) {HOK}, {NEX}, and the abundance of L are related, and (ii) under submaximal curing conditions, all colonies retaining M1 also retain L . There are three pieces of evidence that either {NEX} required {HOK} for replication or {NEX} and {HOK} are on the same plasmid . The evidence is as follows . (i) The great majority of strains containing {HOK} also contain {NEX} . However, two {HOK} {NEX-o} strains do exist . (ii) Growth at 39 degrees C or growth at 34 degrees C with 3% ethanol or 2-propanol cures {HOK} and {NEX} . In a {HOK} {NEX} strain, the two plasmids are always co-cured . (iii) {HOK} and {NEX} are both maintained in mak4, mak6, and mak27 strains (mak = maintenance of {KIL-k1}), but not in mak3, mak10, and pet18 strains . Strains containing {HOK} and {NEX} have about fourfold more L double-stranded RNA than their isochromosomal, cured derivatives . In addition, a cytoductant which has acquired {HOK} and {NEX} has fourfold more L than its parent . These results are consistent with either {HOK} being a form of L or {HOK} increasing the copy number of L . Using a K1 killer strain in which L, as well as M1, could be cured by growth at 38 degrees C, we examined the distribution of loss of M1 and L under conditions giving 98% M-o colonies and at least 50% L-o colonies . No M1L-o colonies were observed, supporting the previous suggestion by others that M1 requires L. Nucleic Acids Res, 1982 Apr 24, 10(8), 2625 - 37 Conservation of high efficiency promoter sequences in Saccharomyces cerevisiae; Dobson MJ et al.; The position of the yeast phosphoglycerate kinase (PGK) gene has been mapped on a 2.95kb Hind III fragment . We have determined the nucleotide sequence of the 5' flanking region and compared this sequence with those from 16 other yeast genes . PGK, like all other yeast genes has an adenine residue at position -3 . It has two possible TATA boxes at positions -114 and -152 and a CAAT box at -129 . In addition we have defined a structure at position -63 to -39 that is common to all yeast genes that encode an abundant RNA . This structure is a CT-rich block followed, about 10 nucleotides later, by the sequence CAAG. Biochim Biophys Acta, 1982 Apr 23, 687(1), 57 - 62 The isolation of Saccharomyces cerevisiae nuclear membranes with nuclease and high-salt treatment; Mann K et al.; Saccharomyces cerevisiae nuclear membranes were prepared from isolated nuclei by digesting chromatin with deoxyribonuclease and ribonuclease, washing of residual nuclei with 0.5 M MgCl2, and discontinuous gradient centrifugation in buffered Ficoll solutions . Electron microscopic examination of the preparations showed single membrane and double membrane vesicles and membrane sheets . Pores or residual pores were often visible . In double membrane profiles the two unit membranes were often separated by the remains of the perinuclear cistern . The nuclear membrane fragments contained 58% protein, 23.8% phospholipid, 6% sterols, 7.1% neutral acylglycerols, 4.8% RNA, and 0.3% DNA . The phospholipid content of the membrane preparations was influenced by a phospholipase activity with acidic pH optimum. Mol Cell Biol, 1982 Apr, 2(4), 457 - 66 Influence of the nuclear gene tmp3 on the loss of mitochondrial genes in Saccharomyces cerevisiae; Zelikson R et al.; The Saccharomyces cerevisiae tmp3 mutant is deficient in the mitochondrial enzyme complex that participates in the formation of one-carbon-group-tetrahydrofolate coenzymes, serine transhydroxymethylase, dihydrofolate reductase, and thymidylate synthetase, thus leading to multiple nutritional requirements of dTMP, adenine, histidine, and methionine . The tmp3 mutant quickly loses its mitochondrial genome even when grown on fully supplemented medium or on a high concentration of 5-formyl tetrahydrofolate, which replaces all the four requirements . A study of the loss of the mitochondrial genome by following several mitochondrial genetic markers showed that there was a preferential specific loss of a large region of the mitochondrial genome, covering mit ts983, Er, Cr, and mit ts982 up to OrI, and retention of the region of Pr and mit tscs1297 . A kinetic study showed that there was a preferentially rapid loss of the region covering the mit+ alleles ts983 to tscs902 at the rate of 10% per generation. Mol Cell Biol, 1982 Apr, 2(4), 450 - 6 Oligoadenylate is present in the mitochondrial RNA of Saccharomyces cerevisiae; Yuckenberg PD et al.; We exa