Z Allg Mikrobiol, 1976, 16(4), 263 - 72 {Protein crystals and tubuli bundles in yeast cells . IV . Biochemical and electron microscopic studies of the induction of alcohol dehydrogenase (ADH) crystals}; Kunkel W; Cells of Saccharomyces carlsbergensis H 60 synthesize alcohol dehydrogenase (ADH) in media containing 2% lactat, 1% ethanol or 0.1% glucose . Crystals may be induced in protoplasts of these cells . Increase of glucose concentration in the medium results in diminished ADH synthesis and decreased tendency for crystal formation . Repression of ADH synthesis by glucose results in the formation of a protein (MG 110000 D), the significance of which is discussed . Early stages of crystal formation inside the cell are demonstrated electronmicroscopically . At first dense material accumulates between opposite membranes of neighbouring mitochondria . Within mitochondria frequently membrane bundles occur in close vicinity to crystals . These ADH-crystals arise from this material. Acta Chem Scand B, 1976, 30(1), 43 - 8 Purification of alkaline phosphatase of the halotolerant yeast Debaryomyces hansenii; Adler L; Alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) of the halotolerant yeast Debaryomyces hansenii was purified by a procedure involving cell disruption, DNAase treatment, ethanol precipitation, gel filtration, chromatography on DEAE-Sephadex, and preparative polyacrylamide gel electrophoresis . The specific activity was increased 1250-fold as compared to the activity of cell free extract . The total recovery was 30% . Various modifications of the growth conditions had slight or no effect on the yield of enzyme. Can J Microbiol, 1976 Jan, 22(1), 35 - 42 Regulatory properties of yeast nitrate reductase in situ; Choudary VP et al.; A simple and rapid procedure to make yeast cells permeable by agitating with toluene-ethanol, (TE) 1:4, v/v was developed . The permeated cells retained their ability to catalyze certain enzyme reactions . Temperature and duration of agitation during TE treatment played an important role in retention of the catalytic potential of permeated cells . The in situ assay using permeated cell preparations was more sensitive even in the absence of added cofactors than in the vitro assay in detecting assimilatory nitrate reductase (NAD(P)H:nitrate oxidoreductase, EC 1.6.6.2) (NAR) activity in Candida utilis . Using in situ assay technique, different mechanisms regulating the biosynthesis of NAR in C . utilis were investigated . Nitrogen starvation did not lead to derepression of NAR . NO3-ions were absolutely essential for induction and maintenance of high levels of NAR activity . Cells grown on ammonium nitrate possessed relatively lower levels of NAR . Kinetics of NAR induction were followed as a function of time and inducer concentration . The influence of various cations on the induction of NAR by nitrate was investigated . A wide range of D-amino acids induced NAR synthesis . Of 22 L-amino acids tested only phenylalanine induced significant levels of NAR . Various intermediates of the pathway of nitrate reduction influenced the rate of NAR induction . There was a rapid disappearance of in vivo activity of the enzyme of induced yeast cells on nitrogen starvation, and the rate of loss was accelerated by the presence of NH4+. Acta Biochim Pol, 1976, 23(4), 357 - 67 Formation of lipid-bound N-acetylhexosamine derivatives in yeast particulate fractions; Palamarczyk G; 1 . Particulate fraction (105 000 g) from Saccharomyces cerevisiae catalyses the transfer of N-acetylglucosamine from UDP-N-acetyl{14 C} glucosamine into lipid fraction as well as to insoluble polymer . 2 . The evidence presented is in favour of the lipid containing the N-acetylglucosamine mono-, di- and tri-saccharide derivatives of dolichyl diphosphate . 3 . The presence of a transferase synthesizing dolichyl-linked sugars in mitochondrial fraction is also reported. Biochimie, 1976, 58(1-2), 239 - 42 The utilization of rare and unnatural pentoses by yeast Torulopsis candida; Karassevitch NY; Adaptation of yeast torulopsis candida to D-arabinose, D-lyxose and L-oxylose is shown to be due to the appearance of a new enzyme which catalyzes the reduction of these pentoses to D-arabitol and xylitol, respectively . The appearance of the enzyme is not coupled with the altered state of polyol : NADP-oxidoreductase (1.1.1.21) catalyzing the reduction of D-xylose and other aldoses with their second carbon atom having a stereoconformation of D-glyceraldehyde . Some proposals are made on improvements of the nomenclature of the enzymes catalyzing the reduction of the two groups of pentoses. Z Allg Mikrobiol, 1976, 16(8), 615 - 25 Regeneration of yeast protoplasts . A freeze-etching study; Necas O et al.; The submicroscopical structure of yeast protoplasts regenerating the new cell wall or merely its fibrillar component was studied by freeze-etching . No relation was found between the number and distribution of plasma membrane particles at various stages of regeneration . Hexagonal arrangement of the particles was found only solitarily even in protoplasts synthesizing intensely glucan microfibrils in liquid media . The fibrillar network on protoplasts grown in liquid medium or fibrillar groundwork of the cell wall on protoplasts grown in gelatine medium were exposed only after etching on etched faces . The microfibrils did not penetrate the outer leaflet of the unit membrane, which consequently indicates that no structural relation could exist between the fibrils and the plasma membrane particles . During conversion of cells to protoplasts, plasma membrane invaginations were arranged end-to-end to form prolonged furrows which persisted until cell wall regeneration had been completed . Then the long furrows broke into short units . Thus plasma membrane invaginations appear to be loca, rigid differentiations of the plasma membrane which may migrate laterally . Neither the plasma membrane nor the adjacent cytoplasm showed signs of reverse pinocytosis . The endoplasmic reticulum, which was hypertrophic during regeneration, consisted of extensive membranes, often parallel in arrangement . The cytoplasm frequently contained groups of small globular particles without characteristic localization. Folia Microbiol (Praha), 1976, 21(6), 459 - 64 Biosynthesis of yeast mannan . Characterization of mannan-synthesizing enzyme systems from mutants defective in mannan structure; Farkas V et al.; The yeast Saccharomyces cerevisiae X2180-1A (wild) and its mutants X2180-1A-4 (mnn 1) and X2180-1A-5 (mnn 2) defective in mannan biosynthesis were used as enzyme sources to catalyze in vitro mannosyl transfer from GDP-{14C-U}-mannose to endogenous glycoproteins as well as to exogenous, low-molecular weight acceptors . While the enzyme preparation from the wild strain exhibited all mannosyl transferase activities involved in mannan biosynthesis by catalyzing the synthesis of characteristic mannoprotein, the enzyme from mnn 1 mutant failed to catalyze the synthesis of alpha(1 leads to 3) mannoside linkages both with endogenous as well as with exogenous acceptors . The enzyme preparation from the mnn 2 mutant catalyzed the formation of mannoprotein very similar to that obtained with the enzyme from the wild strain . The most important difference was the formation of a higher number of unsubstituted mannosyl units in the alpha(1 leads to 6) linked mannan backbone . The observed results support the hypothesis that in the mnn 1 the mutation has altered the structural gene involved in biosynthesis of an alpha(1 leads to 3) mannosyl transferase catalyzing the addition of alpha(1 leads to 3) linked mannosyl units to alpha(1 leads to 2) linked mannotrioses in the polysaccharide side chains and in the oligosaccharides attached to serine and/or threonine in the protein part of mannan molecule . The mnn 2 mutant represents most probably a kind of regulatory mutation where the activity of an alpha(1 leads to 2) mannosyl transferase adding the mannosyl units directly to alpha(1 leads to 6) linked backbone in the outer region of polysaccharide part of yeast mannan is repressed in vivo but becomes significant in vitro. Biochimie, 1976, 58(7), 837 - 42 Some properties of yeast mitochondria prepared by a rapid mechanical procedure; Chambon H et al.; A method is described for preparing yeast mitochondria rapidly (within one hour) by using the MSK Bronwill Cell homogenizer . Yeast mitochondria obtained by the method exhibit relatively good respiratory controls and ADP/O ratios . The method is convenient for small or large amounts of yeast cells (from 5 to a hundred grams, wet weight) and gave a yield of 3 to 5 mg protein/g wet weight of yeast mitochondria. Biochimie, 1976, 58(3), 305 - 16 Complete amino acid sequence of the heme-binding core in bakers' yeast cytochrome b2 (L-(+)-lactate dehydrogenase); Guiard B et al.; We are reporting here an analysis of the chymotryptic peptides obtained from the tryptic heme-binding fragment of flavocytochrome b2 (cytochrome b2 core) . These results completely establish the sequence of the 96 residue-long fragment, for which preliminary evidence has been published before {24} . We also report full experimental details concerning the automatic degradation, the specific cleavages at the unique arginine and methionine residues, and the analysis of the tryptic peptides . In addition, it is shown that the main heme-binding fragment resulting from cytochrome b2 proteolysis by yeast proteases has an additional glutamic acid residue at the C-terminal end relative to the main tryptic heme-binding fragment . The slight sequence modifications presented here (amide groups and insertion of a lysine residue after position 71) do not substantially modify the comparison with liver microsomal cytochrome b5 . A new sequence alignment is proposed for the two proteins, and a few structural considerations are presented, based on the inspection of calf liver cytochrome b5 three-dimensional model {50,51}. Mutat Res, 1976 Jan, 34(1), 75 - 92 Analaysis of photoenzymatic repair of UV lesions in DNA by single light flashes . XI . Light-induced activation of the yeast photoreactivating enzyme; Harm H et al.; Photoreactivating enzyme (PRE) from yeast (as semi-crude extract, or in highly purified form) shows increased activity if it is illuminated with near UV or short wavelength visible light prior to its use for photoenzymatic repair of UV-induced pyrimidine dimers in transforming DNA in vitro . This effect results from an alternation in PRE molecules changing those with low activity in the light-dependent step of the reaction to a higher activity . Light-induced activation of PRE preparations is slowly lost by dark storage for several hours to 1 day (faster at 23 degrees C than at 5 degrees C), but can be recovered repeatedly by renewed preillumination . The action spectrum for these preillumination effects generally resembles that for the photoenzymatic repair reaction itself, having its maximum in the same 355-385 nm region as the latter, but light of somewhat longer wavelengths (546 nm) is still effective . Preilluminated PRE is also more stable to thermal inactivation (65 degrees C) than untreated enzyme. Biochimie, 1976, 58(1-2), 71 - 80 Further characterization of yeast RNA polymerases . Effect of subunits removal; Huet J et al.; Two forms of yeast RNA polymerase A are resolved by phosphocellulose chromatography . One of these, called RNA polymerase A, is lacking two polypeptide chains of 48,000 and 37,000 daltons . The properties of the two enzymes are compared in the present paper . RNA polymerase A transcribes d(A-T)n with a similar efficiency as the complete enzyme, but it is comparatively much less active with native DNA . The two enzymes can also be differentiated on the basis of their ionic strength and divalent cation requirements . RNA polymerase A has a particularly low activity at high salt and low Mg2+ concentrations . Thermal inactivation curves of the two enzymes are different when residual activity is assayed with native DNA . In contrast with d(A-T)n as template the apparent inactivation curves of the two enzymes are identical . The data suggest that the two dissociable polypeptide chains play an important role in transcription . The template specificity of yeast RNA polymerase B was further investigated using SV40 DNA-FI as template . RNA polymerase B is able to retain {3H}SV40 DNA-FI on nitrocellulose filters but the enzyme-DNA complex is very unstable . The observation that RNA polymerase B can transcribe to some extent a supercoiled DNA but not a linear double stranded template supports the hypothesis that the enzyme needs some unpaired DNA structure to initiate transcription. Biochimie, 1976, 58(1-2), 19 - 25 Studies of the regulation and reaction mechanism of the carbamyl phosphate synthetase and aspartate transcarbamylase of bakers' yeast; Lue PF et al.; Kinetic studies of the carbamyl phosphate synthetase activity (CPSase) of bakers' yeast revealed an absolute requirement for K+ ions ; KM values for two of the substrates, glutamine and bicarbonate, were found to be 5 X 10(-4) M and 3 X 10(-3) M respectively . CPSase activity of the purified enzyme aggregate (M.W . 800,000) was extremely sensitive to UTP with a Ki of 2.4 X 10(-4) M . The purine nucleotide intermediate, XMP, was a strong activator of CPSase, acting at a site different from the regulatory site at which UTP binds ; XMP activation diminished at high concentrations of the substrate Mg-ATP . Studies of the reaction mechanism of CPSase revealed that it involved the sequential addition of the substrates bicarbonate and Mg-ATP, liberation of ADP, addition of glutamine, binding of ATP and then release of ADP and the product carbamyl phosphate . Studies of the reaction mechanism of the aspartate transcarbamylase (ATCase) of the aggregate yielded data which were not compatible with any of the usual models ; whichever reaction mechanism is ultivately found to fit the data, it will probably prove applicable both to the ATCase of the aggregate and to the disaggregated ATCase subunit (MW 138,000). Prep Biochem, 1976, 6(2-3), 153 - 75 Isolation and partial charcterization of a cytochrome b complex and cytochrome oxidase from yeast mitochondria; Marjanen LA; A cytochrome b complex and cytochrome oxidase have been purified 14- and 20-fold respectively from yeast submitochondrial particles by a simple procedure involving their spontaneous precipitation from a deoxycholate extract . The recovery of both proteins was almost quantitative . The specific heme contents were 11 and 8 nmoles/mg protein for the cytochrome b complex and cytochrome oxidase respectively and both were spectrally pure . Sodium dodecyl sulfate gel electrophoresis resolved the cytochrome b complex into seven distinct subunits with molecular weights 42,000, 33,000, 27,500, 23,000, 15,500, 13,000 and 10,500 . Cytochrome oxidase contained five bands with molecular weights 42,000, 26,500, 21,000, 14,000 and 10,500. Proc Natl Acad Sci U S A, 1976 Jan, 73(1), 73 - 6 A ribosome-dependent GTPase from yeast distinct from elongation factor 2; Skogerson L et al.; Three proteins required for poly(U)-directed polyphenylalanine synthesis have been separated from yeast . Two of the factors correspond to the elongation factors 1 and 2 described for other eukaryotic systems, according to the criteria of phenylalanyl-tRNA binding and diphtheria toxin-catalyzed ADP-ribosylation . The third protein, while absolutely required for polyphenylalanine synthesis, was a more active ribosome-dependent GTPase than elongation factor 2. Acta Biol Med Ger, 1976, 35(10), 1273 - 7 The effect of temperature change on the kinetic behaviour of yeast phosphofructokinase; Nissler K et al.; Yeast phosphofructokinase does not exhibit any cold sensitivity . The kinetic properties of the enzyme have been investigated in the range between 10 degrees C and 30 degrees C in dependence on fructose 6-phosphate and ATP . Although a significant increase in the enzyme activity with rising temperature does not occur, the shape of the ATP velocity curves is not markedly altered . With increasing concentrations of fructose-6-phosphate the efficiency of temperature on the catalytic process increases, indicating a small temperature effect on the shape of the fructose-6-phosphate velocity curves . The results are interpreted in terms of an adequate kinetic model. Acta Microbiol Pol, 1976, 25(3), 199 - 204 Effect of polyamines on yeast cell-free protein synthesizing system . II . Increase stability of cell-free system in the presence of spermine; Jakubowicz T et al.; The addition of spermine, at concentration which stimulates protein synthesis, to the yeast cell-free system significantly increases the thermal stability of the latter . Similar stabilizing effect of polyamine is observed for ribosome-poly U-ac-phe-tRNA complexes . These results suggest that the stimulatory effect of polyamines on the in vitro protein synthesis might be partly due to the increased stability of ribosomes and ribosome-peptydyl-tRNA complexes. Acta Microbiol Pol, 1976, 25(3), 187 - 97 Effect of polaymines on yeast cell-free protein synthesizing system . I . Influence of spermine and spermidine on aminoacyl-tRNA transfer reaction; Wolska-Mitaszko B et al.; Spermine and spermidine added to a Saccharomyces cerevisiae cell-free protein synthesizing system increased phenylalanine polymerization reaction several-fold at suboptimal concentration of Mg2+ and approximately two-fold at optimal amounts of Mg2+ . The addition of polyamines greatly stimulated the enzymatic and nonenzymatic binding of phenylalanyl-tRNA and N-acetylphenylalanyl-tRNA to ribosomes . The binding of the acetylated derivative was higher than phenylalanyl-tRNA, however, as it was shown the former was bound exclusively to the A site of the ribosome . Contrary to the binding process, the puromycin reaction was not stimulated by spermine added at a concentration which enhanced the polyphenylalanine synthesis . These results indicate that polyamines have not only a sparing effect on the Mg2+ requirement for yeast protein synthesis in vitro and suggest that one of the possible sites of polyamines action might be the binding of aminoacyl-tRNA to ribosomes. Acta Biol Med Ger, 1976, 35(1), 7 - 14 {Enzymatic conversion of tetradecanol in heterogenous phase by yeast-alcohol dehydrogenase}; Rothe U et al.; Alcohol dehydrogenase from yeast converts long-chain primary alcohols not only in the dissolved state, but also at the surface of undissolved particles . Tetradecanol beads with a defined surface can be produced and employed as model substrate . The reaction rate was determined by the proton release accomplished in the reaction . The initial reaction rate depends on the enzyme concentration . The relation is nonlinear (vi = k-{e}0,4); the numerical value of the exponent (n = 0.4) argues in favour of a reaction occurring at the interface . The Lineweaver-Burk plots become linear if the substrate concentrations are based on the molar surface concentrations of the particles . The pH optimum for the reaction at the surface is displaced by 0.25 pH units towards the alkaline region (compared with ethanol as substrate) . The activation energy of the reaction with tetradecanol beads as substrate is 30% lower than that for the ethanol oxydation. Biochimie, 1976, 58(1-2), 51 - 9 Effects of activators on chemically modified yeast hexokinase; Menezes LC et al.; Enzymic studies performed with chemically modified yeast hexokinase (ATP : D-hexose-6-phosphotransferase) confirm previous results indicating that the sulfhydryl, imidazol and most of the reactive amino groups do not seem to be directly implicated in the enzyme active site . On the other hand the modification of these functional groups of the enzyme does not affect the transition between the acidic inactive form to an active enzyme form after deprotonation . The chemically modified forms of hexokinase and the native enzyme are affected in the same way by activators (citrate, D-malate, 3-phosphoglycerate and Pi) when the activity was measured at pH 6.6 . Moreover the loss of enzyme activity observed in the course of the chemical modifications is accompanied by an increase of the activation effect . This increase must be related to some reorganization of the enzyme active site in presence of the effectors, since the same effect was observed when hexokinase was denatured with 3M urea at pH 7.5 . However no increase in the activation effect was observed when the denaturation was carried out at pH 6.5 At this pH the loss in activity and the change of optical absorption at 286 nm were much slower than at pH 7.5, which indicates a great difference in the protein structure between these pHs. Mol Gen Genet, 1975 Dec 30, 143(1), 53 - 64 The organization of genes in yeast mitochondrial DNA II . The physical map of EcoRI and HindII + III fragments; Sanders JP et al.; 1 . We have isolated large fragments of the mtDNA of the yeast Saccharomyces carlsbergensis and digested these with restriction endonucleases . The digestion products were separated by electrophoresis in agarose gels . 2 . Endonucleases EcoRI, HindII + III, HpaI, HindIII and HapII yield 9, 11, 6, 0 and greater than 80 fragments, respectively . 3 . By analysis of partial digestion products and by redigesting the fragments obtained with one endonuclease with a second, we have established the order of all EcoRI and HindII + III fragments . The map is circular and its contour length is 22.1 +/- 0.35 mum, in good agreement with earlier estimates of the size of yeast mtDNA, using electron microscopy and renaturation kinetics . 4 . A comparison of the fragmentation pattern of mtDNAs from S . carlsbergensis and various strains of Saccharomyces cerevisiae with endonuclease HindII + III suggests that the overall gene order is similar. Mol Gen Genet, 1975 Dec 30, 143(1), 5 - 11 Selection of spontaneous mutants by inositol starvation in yeast; Henry SA et al.; A new method for the routine isolation of mutations of spontaneous origin in the yeast, Saccharomyces cerevisiae, is reported . The technique is based on the observation that inositol auxotrophs die when deprived of inositol . However, if macromolecular synthesis is inhibited, most of the cells survive . Appropriate manipulation of inositol requiring mutants can therefore result in the selective survival of cells possessing mutations which affect macromolecular synthesis . Since reversion to inositol prototrophy can be a major source of interference in efficient selection, a haploid double mutant strain has been constructed which reverts to inositol prototrophy with a frequency estimated to be several orders of magnitude lower than the expected frequency of single, spontaneous mutational events . Using this strain, enrichment in excess of 10,000 fold has been obtained for various classes of auxotrophic mutants . Spontaneous temperature sensitive mutants have also been obtained. Biochemistry, 1975 Dec 16, 14(25), 5418 - 21 Yeast DNA photolyase: molecular weight, subunit structure, and reconstruction of active enzyme from its subunits; Boatwright DT et al.; Yeast DNA photolyase, purified by affinity chromatography, ran as a single component when analyzed by either electrophoresis on polyacrylamide gradient gels or by sedimentation velocity through 5-20% sucrose gradients containing 0.4 M KCl, and, therefore, was considered homogeneous . The molecular weights of photolyase, determined by these methods, were 130000 and 136000, respectively . When the enzyme was examined by electrophoresis on sodium dodecyl sulfate polyacrylamide gradient gels, it dissociated into two bands whole molecular weights were 60000 and 85000 . After the enzyme was sedimented through sucrose gradients in the presence of 1.0 M KCl, two absorbance maxima, which corresponded to polypeptides of 54000 and 82500, were found in the fractions collected . Thus, the enzyme consists of two dissimilar subunits . When the two fractions that exhibited maximal absorbance were mixed together, a time-dependent increase in activity occurred, demonstrating that active enzyme could be reconstituted from these subunits . Analysis of sucrose gradients containing 1.0 M salt for photolyase activity showed that it was present exclusively in the region of the gradient corresponding to 68200 in agreement with a previous report (J . Cook and T . Worthy (1972), Biochemistry 11, 388) . These active fractions were found in the overlap region between the two subunits, and their activity was attributed to reconstitution of the enzyme during the assay. Biochemistry, 1975 Dec 16, 14(25), 5428 - 37 Subunit interactions in yeast glyceraldehyde-3-phosphate dehydrogenase; Mockrin SC et al.; The spontaneous inactivation of yeast glyceraldehyde-3-phosphate dehydrogenase was found to fit a simple two-state model at pH 8.5 and 25 degrees . The first step is a relatively rapid dissociation of the tetramer to dimers with the equilibrium largely in favor of the tetramer . In the absence of NAD+ the dimer inactivates irreversibly . The apoenzyme is quite stable with a half-life for complete activity loss proportional to the square root of the enzyme concentration . Perturbances of the protein structure (by pH, ionic strength, and specific salts), which have no effect on the tetrameric state of the molecule, result in an alteration of the cooperativity of NAD+ binding, the reactivity of the active-site sulfhydryl group, and the catalytic activity of the enzyme . Covalent modification of two of the four active-site sulfhydryl groups has profound effects on the enzymic activity which are mediated by changes in the subunit interactions . Sedimentation analysis and hybridization studies indicate that the interaction between subunits remains strong after covalent modification . Under normal physiological and equilibrium dialysis conditions the protein is a tetramer . Equilibrium dialysis studies of NAD+ binding to the enzyme at pH 8.5 and 25 degrees reveal a mixed cooperativity pattern . A model consistent with these observations and the observed half-of-the-sites reactivity is that of ligand induced sequential conformational changes which are transferred across strongly interacting subunit domains . Methods for distinguishing negatively cooperative binding patterns from mixtures of denatured enzyme and multiple species are discussed. Mol Gen Genet, 1975 Dec 9, 141(4), 291 - 304 Biogenesis of mitochondria . 43 . A comparative study of petite induction and inhibition of mitochondrial DNA replication in yeast by ethidium bromide and berenil; Nagley P et al.; The action of ethidium bromide and berenil on the mitochondrial genome of Saccharomyces cerevisiae has been compared in three types of study: (i) early kinetics (up to 4 h) of petite induction by the drugs in the presence or absence of sodium dodecyl sulphate; (ii) genetic consequences of long-term (8 cell generations) exposure to the drugs; (iii) inhibition of mitochondrial DNA replication, both in whole cells and in isolated mitochondria . The results have been interpreted as follows . Firstly, the early events in petite induction differ markedly for the two drugs, as indicated by differences in the short-term kinetics . After some stage a common pathway is apparently followed because the composition of the population of petite cells induced after long-term exposure are very similar for both ethidium bromide and berenil . Secondly, both drugs probably act at the same site to inhibit mitochondrial DNA replication, in view of the fact that a petite strain known to be resistant to ethidium bromide inhibition of mitochondrial DNA replication was found to have simultaneously acquired resistance to berenil . From consideration of the drug concentrations needed to inhibit mitochondrial DNA replication in vivo and in vitro it is suggested that in vivo permeability barriers impede the access of ethidium bromide to the site of inhibition of mitochondrial DNA replication, whilst access of berenil to this site is facilitated . The site at which the drugs act to inhibit mitochondrial DNA replication may be different from the site(s) involved in early petite induction . Binding of the drugs at the latter site(s) is considered to initiate a series of events leading to the fragmentation of yeast mitochondrial DNA and petite induction. Biochim Biophys Acta, 1975 Dec 4, 414(2), 115 - 25 Detailed analysis of the ribosomal RNA synthesis in yeast; Trapman J et al.; In order to study the biosynthesis of ribosomal RNA in Saccharomyces carlsbergensis the labelling kinetics of the various precursor and mature rRNA species were determined using pulse-labelling of protoplasts with {5-3H} uridine at 15 degrees C . Label appears almost immediately in 37 S RNA, the precursor common to both 26 S and 17 S rRNA . Labelled 29 S and 18 S RNA, the immediate precursors of 26 S and 17 S rRNA respectively, were found to appear about 4 min and about 8 min after addition of the isotope respectively . These data indicate that the topography of the 37 S precursor RNA is: 5'-17 S -26 S-3' . The pool size of 29 S RNA is about twice as large as that of either 37 S or 18 S RNA, indicating that under the conditions used processing of 18 S to 17 S rRNA proceeds more rapidly than processing of 29 S to 26 S rRNA . The labelling kinetics of 5.8 S rRNA are in agreement with the existence of a 7 S precursor rRNA, the identity of which was previously established (Trapman, J., de Jonge, P . and Planta, R.J . (1975) FEBS Lett . 57, 26--30) and which, in turn, probably is derived from 29 S precursor rRNA . The labelling kinetics of 5 S rRNA suggest that 5 S RNA sequences, rather than also being part of the common 37 S precursor, are located on a separate primary transcription product . Whether this transcript still contains excess sequences remains to be determined . However, because of the rapid appearance of labelled 5 S RNA, such a precursor would have to be very short lived. Mol Biol Rep, 1975 Dec, 2(4), 321 - 5 The molecular weights of yeast ribosomal precursor RNAs; Brand RC et al.; The molecular weights of the predominant rRNA precursors as well as those of 26-S and 17-S mature rRNA from Saccharomyces carlsbergensis were determined by polyacrylamide gel electrophoresis in the presence of formamide . Mature 26-S + 5.8-S rRNA was found to have a molecular weight of 1.24 X 10(6) while their immediate precursor, 29-S RNA, had a molecular weight of 1.52 X 10(6) . Values of 0.70 X 10(6) and 0.82 X 10(6) were obtained for the molecular weights of mature 17-S rRNA and its 18-S precursor . Finally the 37-S precursor, common to both 29-S and 18-S RNA, was found to have a molecular weight of 2.80 X 10(6) . Each precursor rRNA, therefore, contains extra sequences not found at the next stage of maturation. Proc Natl Acad Sci U S A, 1975 Dec, 72(12), 4866 - 70 Hydrogen bonding in yeast phenylalanine transfer RNA; Quigley GJ et al.; Further analysis of the three-dimensional electron density map of yeast phenylalanine tRNA is presented . Attention is focused on the several types of unique hydrogen bonding that are found in the molecule and a number of sections of the electron density map are presented . These sections are compared with an electron density map of a dinucleoside phosphate . The bases in the helical stem regions are all involved in Watson-Crick hydrogen bonding interactions with the exception of the guanine-uracil base pair . Several additional tertiary hydrogen bonding interactions are described. Mutat Res, 1975 Dec, 30(3), 317 - 26 The effect of caffeine on survival of UV-irradiated diploid yeast strains of different sensitivities; Kiefer J; The action of caffeine post-treatment after UV exposure in three strains of diploid yeast has been studied . The addition of the drug to the plating medium reduced survival in all cases . Higher colony-forming abilities were found in all strains when the UV dose had been split into two fractions with an interval of about 6 h . Caffeine added to the incubation medium between dose fractions did not interfere with this process in the wild type but suppressed split-dose sparing completely in two sensitive strains. J Bacteriol, 1975 Dec, 124(3), 1586 - 93 Timing and function of chitin synthesis in yeast; Cabib E et al.; A temperature-sensitive mutant of Saccharomyces cerevisiae, L-2-42, is blocked at 37 C at a stage of the cell cycle prior to septum formation . When single cells of the mutant are allowed to bud at 37 C in a medium containing tritiated glucose, a large incorporation of radioactivity into chitin takes place . Thus, the synthesis of chitin, the major component of the primary septum, is initiated in a phase of the cell cycle which precedes septum closure . This early period of chitin synthesis is not required for emergence and growth of buds because, in the wild type, budding takes place normally in the presence of concentrations of polyoxin D that effectively and specifically prevent chitin formation . However, at a later time a majority of these cells lyse, presumably because of the inability to form a septum . Polyoxin D also prevents the appearance of enhanced fluorescence at the junction between mother cell and bud, as observed in the presence of a brightener . Therefore, the fluorescence is due to chitin and its presence at the base of very early buds indicates that chitin synthesis begins at or shortly after bud emergence . A scheme for chitin synthesis and primary septum formation which embodies these and other results is presented. Biochim Biophys Acta, 1975 Dec 1, 413(2), 248 - 51 Effect of tetraphenylboron upon the uptake of the lipophilic cation dibenzyldimethylammonium by yeast cells; Hoeberichts JA et al.; The rate of uptake of the lipophilic cation dibenzyldimethylammonium by yeast cells is increased by tetraphenylboron . However, tetraphenylboron increases also the equilibrium partition of dibenzyldimethylammonium between cells and medium, probably because a complex between tetraphenylboron and dibenzyldimethylammonium is trapped inside the cells . Accumulation of dibenzyldimethylammonium in the presence of tetraphenylboron is not reversed by dinitrophenol, whereas accumulation of the lipophilic cation in the absence of tetraphenylboron appears to be almost completely reversible. Gann, 1975 Dec, 66(6), 697 - 700 Loss of mitochondrial DNA in respiration-deficient mutant of yeast induced by 4-nitroquinoline 1-oxide; Morita T et al.; The loss of mitochondrial DNA was found in a cytoplasmic respiration-deficient mutant of yeast, strain N-1, induced by treatment of a normal yeast with 4-nitroquinoline 1-oxide . In cesium chloride density gradient centrifugation, mitochondrial DNA from the normal yeast showed a density of 1.684 g/ml, but mitochondrial fraction of respiration-deficient mutant strain N-1 had no detectable DNA at a densty of 1.684 g/ml or near it . Though an incorporation of 3H-adenine into mitochondrial DNA was amplified by the presence of cyclohemimide, the mutant had no detectable radioactivity in its mitochondrial fractions . Accordingly, it was concluded that respiration-deficient mutant strain N-1 has lost its mitochondrial DNA which was indispensable for the respiratory activity of yeast cells. Nucleic Acids Res, 1975 Dec, 2(12), 2329 - 41 Yeast phenylalanine transfer RNA: atomic coordinates and torsion angles; Quigley GJ et al.; The atomic coordinates of yeast phenylalanine transfer RNA (tRNA) as well as the torsion angles of the polynucleotide chain are presented as derived from an x-ray diffraction analysis of orthorhombic crystals . A comparison is made between the coordinates obtained from analysis of monoclinic crystals of the same material . It is concluded that the molecule has substantially the same form in the orthorhombic and the monoclinic lattices, except for differences found between residues at the 3' end of the polynucleotides chain . A number of observations are made concerning hydrogen bonding interactions which may account for many of the residues conserved in all tRNA sequences. Mutat Res, 1975 Dec, 33(2-3), 179 - 86 Genetic effects of formaldehyde in yeast . I . Influence of the growth stages on killing and recombination; Chanet R et al.; In random cultures, stationary phase cells of Saccharomyces cerevisiae are more resistant to killing induced by formaldehyde than are exponentially growing cells . It is shown that this compound induces intra- and intergenic recombination in this eucaryotic organism . In synchronized populations the lag and G1 phases demonstrate the higher resistance to both killing and induction of recombinants by formaldehyde whereas maximal sensitivity occurs during the end of G2 and/or the mitotic division . This pattern in contrast with that found after treatments by ionizing or ultraviolet radiations. Mutat Res, 1975 Dec, 33(2-3), 165 - 72 The gene dosage effect of the rad52 mutation on X-ray survival curves of tetraploid yeast strains; Ho KS; The mutation rad52 in the yeast Saccharomyces cerevisiae confers sensitivity to X-rays . The gene dosage effect of this mutation on X-ray survival curves of tetraploid yeast strains is shown . With increasing number of rad52 alleles, both a decrease in the survival for a given dose and a decrease in the survival curve shoulder width are observed . The generation of such a family of survival curves using three different mathematical models is discussed. Mutat Res, 1975 Dec, 33(2-3), 147 - 56 Inactivation and mutation of yeast cells by hydrogen peroxide; Thacker J; It has been found that inactivation and mutation to respiratory deficiency of yeast cells can be induced by hydrogen peroxide treatment . However, considerable inconsistencies were encountered in measuring these responses . The inconsistencies were found to arise from differences in the abilities of cells in different metabolic states to destroy H2O2 and in the intrinsic sensitivities of cells in different growth states . Parallels are drawn with previous inactivation data from bacterial studies suggesting reparable lesions in DNA provide a useful model to explain H2O2-induced inactivation, but it is not yet possible to eliminate alternative interpretations . Mutation induction in stationary phase cells is strongly depressed at high "doses" of H2O2 (or low cell survival), as is found with a variety of other agents. Genetics, 1975 Dec, 81(4), 615 - 29 Mapping and gene conversion studies with the structural gene for iso-1-cytochrome C in yeast; Lawrence CW et al.; We have investigated the order of the four genes cyc1, rad7, SUP4, and cdc8 which form a tightly linked cluster on the right arm of chromosome X in the yeast Saccharomyces cerevisiae . Crossing over and coconversion data from tetrad analysis established the gene order to be centromere-cyc1-rad7-SUP4 . Also cdc8 appeared to be distal to SUP4 on the basis of crossovers that were associated with conversion of SUP4 . The frequencies of recombination and the occurrence of coconversions suggest that these four genes are contiguous or at least nearly so . Gene-conversion frequencies for several cyc1 alleles were studied, including cyc1-1, a deletion of the whole gene that extends into the rad7 locus . The cyc1-1 deletion was found to be capable of conversion, though at a frequency some fivefold less than the other alleles studied, and both 3:1 and 1:3 events were detected . In general 1:3 and 3:1 conversion events were equally frequent at all loci studied, and approximately 50% of conversions were accompanied by reciprocal recombination for flanking markers . The orientation of the cyc1 gene could not be clearly deduced from the behavior of the distal marker SUP4 in wild-type recombinants that arose from diploids heteroallelic for cyc1 mutations. J Biochem (Tokyo), 1975 Dec, 78(6), 1353 - 64 Development of mitochondrial membranes in anaerobically grown yeast cells; Nagata I et al.; Biochemical analyses of mitochondrial marker substances, especially cardiolipin and oligomycin-sensitive ATPase {EC 3.6.1.3}, as well as electron microscopic observations were carried out to eludicate the process of mitochondrial development in annaerobic yeast cells . Cardiolipin was found to be localized in the mitochondria in anaerobic cells . Its cellular content was a little higher in the stationary phase than in the exponential phase in glucose-grown cells and increased further in galactose-grown cells . The lipid content of the mitochondrial preparation obtained from glucose-grown stationary cells was nearly as high as that from galactose-grown cells . It was also comparable to that of aerobic cells in the stationary phase, where mitochondria are fully developed . Both cellular and mitochondrial levels of oligomycin-sensitive ATPase activity were also found to rise markedly in galactose-grown anaerobic cells, although not in stationary phase cells grown anaerobically on glucose . These high levels of the mitochondrial markers indicate a developmental change in mitochondrial structure even in anaerobically grown cells, which lack mitochondrial cytochromes . In the process of aerobic adaptation, respiratory system formation was observed to occur much faster in galactose-grown cells than in glucose-grown cells, and not to be inhibited by chloramphenicol and high concentrations of glucose structure in anaerobic cells . The developmental change was also corroborated by electron microscopic observations, which revealed the occurrence of two types of mitochondria in anaerobic cells . One was found in glucose-repressed cells and was characterized by the presence of numerous electron-dense granules in the matrix . In contrast, the other type, found in glucose-derepressed cells, had an electron-lucent matrix . No crista membrane was seen in either type of mitochondria in anaerobic cells, although the infoldings of the inner membrane, which partition the matrix into two parts and therefore are called "septum membranes," appeared frequently in the stationary phase cells . On the basis of these results, the process of mitochondrial development in yeast cells is discussed. Proc Natl Acad Sci U S A, 1975 Dec, 72(12), 4966 - 70 High resolution 31P nuclear magnetic resonance studies of intact yeast cells; Salhany JM et al.; High resolution 31P nuclear magnetic resonance (NMR) spectra at 145.7 MHZ are presented for intact yeast cells . Several peaks are resolved and assigned . They include the middle phosphate peaks from long chain or cyclic polyphosphates . Our results are consistent with the suggestion that these polyphosphates act as a phosphate store in the cell . We have also been able to measure cytoplasmic pH using the orthophosphate peak inside the cell, as compared with outside the cell . The results show that yeast cells maintain their cytoplasmic pH around 6.3 . This value is considerably higher than the acidic extracellular pH at which they normally live . These preliminary results indicate that 31P NMR at 145.7 MHZ can be a rapid, informative, and non-invasive method for probing biochemical events within living cells. J Bacteriol, 1975 Dec, 124(3), 1604 - 6 Simple and sensitive procedure for screening yeast mutants that lyse at nonpermissive temperatures; Cabib E et al.; After mutagenesis, surviving yeast cells are grown on plates at 25 C and later exposed to 37 C . The plates are then overlaid with a soft agar containing p-nitrophenylphosphate at pH 9.7 . Lysed cells liberate alkaline phosphatase which gives rise to a yellow color on and around colonies. Mol Gen Genet, 1975 Nov 24, 141(2), 185 - 8 The mating reaction in yeast . II . Spontaneous occurrence of omni-mating types; Balmire J; Meiosis in diploids of Saccharomyces cerevisiae either homozygous or heterozygous for the dmt gene result, in about 5% of the meiotic products, in spores which have undergone an interconversion at the mating-type locus . Some of these interconversions appear to be the result in the generation of spontaneous omni-mating strains . This phenomenon has now been quantitated and the distribution of mating-type loci in these "natural" amni-mating types determined. Biochim Biophys Acta, 1975 Nov 20, 410(1), 21 - 31 Yeast glutathione reductase . Studies of the kinetics and stability of the enzyme as a function of pH and salt concentration; Moroff G et al.; 1 . The pH dependencies of the apparent Michaelis constant for oxidized glutathione and the apparent turnover number of yeast glutathione reductase (EC 1.6.4.2) have been determined at a fixed concentration of 0.1 mM NADPH in the range pH 4.5--8.0 . Between pH 5.5 and 7.6, both of these parameters are relatively constant . The principal effect of low pH on the kinetics of the enzyme-catalyzed reaction is the observation of a pH-dependent substrate inhibition by oxidized glutathione at pH less than or equal 7, which is shown to correlate with the binding of oxidized glutathione to the oxidized form of the enzyme . 2 . The catalytic activity of yeast glutathione reductase at pH 5.5 is affected by the sodium acetate buffer concentration . The stability of the oxidized and reduced forms of the enzyme at pH 5.5 and 25 degrees C in the absence of bovine serum albumin was studied as a function of sodium acetate concentration . The results show that activation of the catalytic activity of the enzyme at low sodium acetate concentration correlates with an effect of sodium acetate on a reduced form of the enzyme . In contrast, inhibition of the catalytic activity of the enzyme at high sodium acetate concentration correlates with an effect of sodium acetate on the oxidized form of the enzyme. Eur J Biochem, 1975 Nov 15, 59(2), 415 - 21 Temperature-sensitive mutants of the yeast fatty-acid-synthetase complex; Knobling A et al.; By genetic complementation analysis, 88 independently isolated temperature-sensitive fatty acid synthetase mutants have been assigned to the six different fas-complementation groups II (fas 1), III (fas 1), Vb (fas 1), VI (fas 2), VIII (fas 2) and IX (fas 2) . The complementation groups Va, Vc, Vd, IV and VII observed among nonconditional fas-mutants have not been found among the temperature-sensitive strains studied . From the failure to detect pantetheine-deficient conditional fas-mutants it is concluded that the yease acyl-carrier protein has an exceptionally stable tertiary structure . Furthermore, the lack of temperature-sensitive mutants of complementation group IV possibly indicates that this group specifically represents only nonsense and frameshift mutations . Almost half of the temperature-sensitive fas 1 and fas 2 mutants studied exhigited non-complementing characteristics . These results confirm the existence of non-complementing fas1 and fas2 missense mutations . From this it is concluded that both fatty acid synthetase loci encode multifunctional polypeptide chains rather than several monofunctional component enzymes . The possible existence of an independent acyl-carrier protein, as suggested by the genetic data reported in this study, is discussed . With 10 different temperature-sensitive fas1 and fas2 mutants the dependence of cellular growth rates on growth temperature and fatty acid supplementation was determined . With all mutants studied fatty-acid-independent growth was completely suppressed at non-permissive temperatures (34 -37 degrees C) . In fatty-acid-supplemented media, however, these mutants exhibited the same growth characteristics as wild-type yeast cells . In contrast to this, wild-type yeast growth was found to be fatty-acid-independent at all temperatures studied . Other than in vivo, the purified fatty acid synthetase isolated from five different temperature-sensitive fas1 and fas2 mutants exhibited in vitro no increased thermolability compared to the wild-type enzyme . From this it is concluded that the specific conformation of fatty acid synthetase subunits either forms only at the ribosomal level during translation, or that this conformation is stabilized by the assembly of subunits into the multienzyme complex structure. Eur J Biochem, 1975 Nov 15, 59(2), 319 - 25 Limited proteolysis of yeast phosphofructokinase by subtilisin . Alterations in enzyme activity, subunit composition, and hydrodynamic properties; Taucher M et al.; Yeast phosphofructokinase having a molecular weight of 750000--800000 (20 S) has been subjected to limited proteolysis by subtilisin and yeast proteases . Two steps of proteolytic degradation could be distinguished: in the first step, which is accompanied by an increase in molecular activity, the subunits alpha and beta (Mr 120000) are converted to alpha' and beta' (Mr approximately 900000), and in the second step, accompanied by a decrease in enzyme activity, alpha' is converted to alpha'' (Mr 80000) and two further fragments having Mr 45000 and 35000 become detectable . In the course of the conversion the sedimentation value of the undissociated enzyme drops from 20 S to about 17 S . The two substrates fructose 6-phosphate and ATP exhibit characteristic protective effects on enzyme activity and on subunit degradation . Whereas the first step is not strongly influenced by the substrates, fructose, 6-phosphate inhibits significantly the degradation of alpha' and beta', whereas ATP prevents only degradation of beta' . When in presence of ATP alpha' is degraded to alpha'', the quaternary structure of the 17-S enzyme is no longer stable and a dissociation of the molecule occurs to a 12-S form which is enzymically active and ATP-sensitive and in which the ratio of alpha'' to beta'' is one-to-one. Eur J Biochem, 1975 Nov 15, 59(2), 423 - 32 Yeast hexokinase A . Succinylation and properties of the active subunit; Rossi A et al.; Yeast hexokinase A (ATP:D-hexose 6-phosphotransferase, EC2.7.1.1) dissociates into its subunits upon reaction with succinic anhydride . The chemically modified subunits could be isolated in a catalytically active form . The Km values found for ATP and for glucose were of the some order as those found for the native enzyme . Of the 37 amino groups present per enzyme subunit, 2-3 of these groups might be located in the proximity of the region of subunit interactions . The 50% loss of the initial activity, which follows the succinylation of these more reactive amino groups, does not seem to be due to the modification of a residue on the enzyme active site or to a change of the tertiary structure of the protein . This 50%loss of the enzyme activity may be related to the dissociation of the dimer into monomers . Both native enzyme and the succinylated subunits have the same H-dependent denaturation rate profiles in response to 2 M urea . Moreover, the apparent pK of the group involved in the transition from a more stable conformation of the protein in the acid range to a less stable one at alkaline pH seems to be similar to the pK of the group implicated in the transition between the protonated inactive form of the enzyme and an active deprotonated form . The succinylated subunit presents 'negative co-operativity' with respect to ATP at slightly acid pH; however, the burst-type slow transient in the reaction progress curve and the activation effect induced by physiological polyanions, effects observed for the native enzyme, were not detected in the standard experimental conditions with the succinylated subunit. Arch Microbiol, 1975 Nov 7, 105(3), 319 - 27 Polybase induced lysis of yeast spheroplasts . A new gentle method for preparation of vacuoles; Durr M et al.; The polybasic macromolecules DEAE-dextran (diethylaminoethyl-dextran, molecular weight 500000) and poly-DL-lysine (molecular weight 30000-70000) were absorbed with a high affinity by spheroplasts of Candida utilis and subsequently, induced lysis . The extent of lysis of spheroplasts and of the liberated vacuoles was studied under various conditions using alpha-glucosidase activity and soluble arginine as cytoplasmic and vacuolar markers, respectively . Adsorption of polybases was rapidly completed even at 0 degrees C; however, with small doses, lysis was poor at 0-12 degrees C and extensive at temperatures above 12 degrees C . This permitted the completion of adsorption before initiating lysis . The purified vacuoles were also sensitive to polybases though less so than the spheroplasts; however, after lysis of spheroplasts the liberated vacuoles were well protected against the action of polybases . A treatment with polybases which disrupted more than 99% of the spheroplasts left at least 70% of the vacuoles intact . Potassium chloride in high concentrations and calcium chloride in low concentrations inhibited polybase induced lysis of spheroplasts by preventing or even reversing the polybase adsorption . A polyacidic macromolecule, dextran sulfate, could prevent but not reverse the adsorption of polybase and subsequent lysis . Metabolic inhibitors reduced the susceptibility of spheroplasts to polybase induced lysis . Vacuoles isolated from polybase lysed spheroplasts still contained large pools of soluble amino acids, and their ability to transport arginine specifically is a further indication of their functional integrity. Biochemistry, 1975 Nov 4, 14(22), 4907 - 11 Inactivation of rat liver RNA polymerases I and II and yeast RNA polymerase I by pyrodixal 5'-phosphate . Evidence for the participation of lysyl residues at the active site; Martial J et al.; Purified DNA-dependent RNA polymerase forms I (A) and II (B) from rat liver and form I from yeast are rapidly inactivated by pyridoxal 5'-phosphate at pH 8.0 . The inhibition is relatively specific since pyridoxamine 5'-phosphate is not an inhibitor and pyridoxal is about 12 times less effective than pyridoxal 5'-phosphate . The inactivation is reversed by high concentrations of amines, and can be made irreversible by reduction with NaBH4 . Spectral analysis of the inhibited enzyme and its NaBH4 reduction product indicates that a Schiff base forms between the aldehyde group of pyridoxal 5'-phosphate and one or more amino groups of the protein . Nepsilon-Pyridoxyllysine was identified as the only product in acid hydrolysates of the reduced yeast RNA polymerase I-pyridoxal 5'-phosphate complex . Complete inactivation of yeast polymerase I results in the incorporation of 3-4 mol of pyridoxal 5'-phosphate/1 mol of enzyme . DNA and nucleotide substrates partially protect the enzymes from inactivation . These results suggest that one or more lysyl amino groups are critical for the activity of animal RNA polymerases and show that pyridoxal 5'-phosphate is a suitable probe for studying the active sites of these enzymes . Comparison of the present results with those previously obtained with Eschericha coli RNA polymerase in this laboratory suggest a new degree of structural homology between eucaryotic and procaryotic RNA polymerases. Mol Gen Genet, 1975 Nov 3, 141(1), 41 - 58 Zygote heterogeneity and uniparental inheritance of mitochondrial genes in yeast; Birky CW Jr; A number of different crosses between strains of Saccharomyces cerevisiae differing in mitochondrial genotype are analyzed with respect to the extent to which individual zygotes transmit mitochondrial genes from one parent or the other . Many crosses produce two or more distinct classes of zygotes in this respect . Some crosses produce a high frequency of uniparental zygotes, which transmit mitochondrial genes exclusively or nearly so from one parent . Such zygotes cannot be accounted for in terms of an unequal input of mitochondrial DNA molecules from the two parents; they indicate that mitochondrial DNA from one parent is selectively replicated, or mitochondrial DNA from the other parent is selectively destroyed, in the zygote . Multiple zygote classes, and uniparental zygotes, are seen in studies of mitochondrial and chloroplast inheritance in other organisms, and may have a common explanation. Mikrobiologiia, 1975 Nov-Dec, 44(6), 1025 - 9 {Variety of effects of vitamins on yeast cells in aerobic conditions}; Makarova EN; The effect of thiamine and biotin on the processes of cell division, assimilation of glucose, and accumulation of the biomass and nitrogen in the cells was studied with the Candida yeast . The action of the vitamins depended on the source of nitrogen . In some strains, asparagine can substitute for biotin . Biotin has different effect on the production of gamma-aminobutyric acid in Candida pulcherrima, C . guilliermondii . C . tropicalis K3-10 . High concentrations of arginine were found in C . guilliermondii var . membranaefaciens in the presence of biotin . The vitamins did not favour the assimilation of nitrate nitrogen in species which were not adapted to this source of nitrogen. J Natl Cancer Inst, 1975 Nov, 55(5), 1247 - 8 Conversion of nitrosobenzene to N-phenylacetohydroxamic acid by yeast pyruvate decarboxylase; Corbett MD et al.; In the presence of yeast enzyme concentrate or purified yeast pyruvate decarboxylase, nitrosobenzene was converted in part to N-phenylacetohydroxamic acid . This transformation had to be catalyzed by the enzyme, since the incubation of nitrosobenzene with the cofactor of pyruvate decarboxylase did not produce the hydroxamic acid . Similar incubations conducted with phenylhydroxylamine did not yield any detectable amounts of N-phenylacetohydroxamic acid. J Bacteriol, 1975 Nov, 124(2), 959 - 68 Ultrastructural studies of the mycelium-to yeast transformation of Sporothrix schenckii; Garrison RG et al.; Fine details of the internal and external morphology of the in vitro mycelial phase (MP) to yeastlike phase (YP) transition of the dimorphic fungal pathogen Sporothrix schenckii are shown in electron micrographs of ultrathin sections . Morphological transformation at the ultrastructural level was observed to occur by direct formation of budlike structures at the tips and along the hyphae and by oidial cell formation . Direct budding of yeast from conidiospores was not observed . Early transitional forms arising by direct blastic action from the MP possessed conspicuous electron-dense microfibrillar material at the outer limits of the cell wall . The electron density of this microfibrillar material was enhanced by staining with acidified dialyzed iron . It is believed that this extracellular material may be composed in part of an acid mucosubstance . No acid phosphatase activity was associated with this microfibrillar material . This substance was found to be a characteristic of the outer limits of the cell wall of the YP of S . schenckii . Oidial YP cell formation occurred later during the transition . The cell wall of the developing oidial YP transitional form arose from an inner layer of the converting hyphae . No consupicuous alterations of the cytoplasmic content of the parent MP cell was observed during MP-to-YP transition . It is suggested that the MP-to-YP transition of S . schenckii may be regulated by at least two mechanisms involving alterations of the biochemical and/or biophysical nature of the cell wall of the MP cell in response to the conversional stimuli. Mutat Res, 1975 Nov, 30(2), 219 - 28 Ethidium bromide mutagenesis in yeast: protection by anaerobiosis; Pinto M et al.; The mutagenesis by ethidium bromide, an intercalating dye, which induces the mutation from wild type (rho+) to the cytoplasmic respiratory deficient petite (rho-) in Saccharomyces cerevisiae, was studied under aerobic and anaerobic conditions . During growth of anaerobic cells at pH 6.5, ethidium bromide at a concentration of 2 mug/ml is unable to induce rho- mutants whereas under aerobic conditions the entire population is converted into rho- cells within 1 generation at the same drug concentration . With ethidium bromide 10 mug/ml 98% of the anaerobic cells are transformed into rho- in 5.5 h (more than 2 generations) . In non-growing conditions, ethidium bromide 10 mug/ml has no effect in anaerobic cells . 3 h adapted cells used as control, are converted into rho- in 8 h . Increasing the ethidium bromide concentration to 20 mug/ml resulted in the appearance of some rho- mutants in the anaerobic population but marked at the same time the onset of a detectable toxic effect of the drug. Mutat Res, 1975 Nov, 30(2), 199 - 208 A kinetic analysis of spontaneous rho- mutations in yeast; James AP et al.; Spontaneous mutation to the petite state at the level of the individual cell was studied in a haploid strain of yeast by the technique of pedigree analysis . Results indicated that (1) the mutability of rho+ cells within a population in log phase is variable; (2) rho+ mitotic buds are, on the average, about 50% more mutable than the rho+ cells from which they arose; (3) the mutability of a rho+ cell tends to decrease as it produces consecutive buds: (4) the probability that a mother cell will become rho- at or immediately subsequent to cell division is, on the average, one third the probability that its bud will be rho-; (5) most, if not all spontaneous rho- mutant cells contain mitochondrial DNA as judged from suppressiveness measurements . The data indicate that the spontaneous production of a mutant cell is a multi-step process . Neither a replicative advantage of defective mitochondrial DNA nor the existence of a "master" mitochondrial genome provides a satisfactory explanation of the process . Either selective dispensation of defective mitochondria to the bud at cytokinesis or normal retention by the mother cell of factors influencing the amplification or rate of induction of defective mitochondrial DNA could be involved. J Toxicol Environ Health, 1975 Nov, 1(2), 281 - 91 Mutagenicity testing of antischistosomal thioxanthenones and indazoles on yeast; von Borstel RC et al.; Two antischistosomal thioxanthenones, lucanthone and hycanthone, and four antischistosomal indazoles, IA-3, IA-4, IA-5, and IA-6, have been tested for mutagenicity on stationary phase cells of the yeast Saccharomyces cerevisiae . It was shown that, although there are some gaps in the data, hycanthone and IA-6 are mutagenic at pH 7.0, hycanthone is mutagenic at 5.9, and none of the other compounds is mutagenic at either pH . (Because mutagenicity of these compounds at pH 7.0 appears to be related to the presence of a methoxy group at position 5 of the polycyclic ring, it is possible that IA-4 will be mutagenic on yeast when it is tested at pH 7.0.) An excision-repair-deficient strain of yeast is no more sensitive than other strains . It was found from time-concentration studies on lethality that an inverse relation held: cells exposed to a mutagenic compound are more sensitive when time of exposure was varied and concentration of the compound was held constant, and cells exposed to a nonmutagenic compound are more sensitive when concentration is varied and time of exposure held constant . When the compounds were tested on growing cells of yeast in rich media, none of the compounds is mutagenic, although some are lethal . The kinetic behavior in reversion of yeast exposed to these compounds shows marked departures from similar reversion studies where yeast is exposed to radiation, implicating different physiological mechanisms for the alteration of responses of yeast cells exposed to the different mutagens. Hoppe Seylers Z Physiol Chem, 1975 Nov, 356(11), 1703 - 8 Purification of tDNA from yeast; Pirro G et al.; tRNA-tDNA hybrids from yeast have been isolated . The main step in purification was chromatography on a BD-cellulose column with salt gradients and formamide, which separates the hybrid material from excess DNA . The hybrids were characterized by density centrifugation in CS2SO4 and by treatment with alkali and pancreatic ribonuclease . Experiments in which DNA that had been sheared to different molecular weights was used for hybrid formation suggest that the tRNA cistrons are tandemly arranged and that the external spacer DNA is preserved in the tDNA. Proc Natl Acad Sci U S A, 1975 Nov, 72(11), 4414 - 8 Structure of yeast phenylalanine transfer RNA at 2.5 A resolution; Ladner JE et al.; The x-ray analysis of the monoclinic form of yeast tRNAPhe has been taken to a resolution of 2.5 A by the method of isomorphous replacement . The model proposed at 3 A has been confirmed and extended to reveal additional features of the tertiary structure and of the stereochemistry . An extensive hydrogen bonding network is described involving specific interactions between bases and the ribose-phosphate backbone . The structure of a G-U base pair has been solved. J Bacteriol, 1975 Nov, 124(2), 606 - 12 Yeast sterol esters and their relationship to the growth of yeast; Bailey RB et al.; Variation in the percentage of sterols esterified to long-chain fatty acids during cellular growth has been examined . Under all conditions, a constant percentage of sterol esters was maintained during exponential growth . This maintenance level was found to vary with different growth conditions . A sharp increase in the rate of esterification was observed upon entry of the culture into the stationary growth phase . The minor cellular sterol components were found to accumulate after this period of rapid sterol ester synthesis, with a relative decrease in the size of the ergosterol pool . Evidence is presented that sterol esters of ergosterol precursors are unable to be metabolized to ergosterol . Once esterified, the fatty acids do not appear to be scavenged during starvation conditions. J Biochem (Tokyo), 1975 Nov, 78(5), 1001 - 11 Renaturation of yeast inorganic pyrophosphatase denatured in urea and guanidine hydrochloride; Yano Y et al.; The renaturation of yeast inorganic pyrophosphatase {EC 3.6.1.1} (PPiase) denatured in guanidine-HCl and urea was studied . The molecular weight of PPiase was estimated to be ca . 63,000-70,000 by means of Sephadex G-75 column chromatography in 8 M urea and 6 M guanidine-HCl and by electrophoresis on polyacrylamide gel containing 8 M urea . The activities of PPiase denatured in various concentrations of denaturants were measured in the presence and absence of the denaturants . In the presence of the denaturants, enzymatic activity decreased as the denaturant concentration increased up to 1.5 M guanidine-HCl and 4 7 urea . The activities of PPiase denatured in these denaturants were not restored by dilution with buffer . However, the enzymatic activities of PPiase denatured at concentrations higher than 1.5 M guanidine-HCl and 4 M urea were restored by dilution with Tris-HCl buffer (pH 7.5) . The recovery of the enzymatic activities of PPiase denatured in 3 to 6 M guanidine-HCl and 6 to 8 M urea was to a level of about 90% of the native enzyme . Irreversible denaturation of PPiase in lower denaturant concentrations was prevented in the presence of sulfhydryl reagents, dithiothreitol, glutathione, and 2-mercaptoethanol . In irreversibly denatured PPiase, the amount of free SH groups decreased markedly . These results indicated that in lower denaturant concentrations, SH groups in PPiase are very oxidizable and their oxidation may cause irreversible denaturation . In higher denaturant concentrations where PPiase was denatured completely, the SH groups became less reactive . The conformations of renatured PPiases was investigated by means of N-bromosuccinimide oxidation, fluorescence emission spectra and circular dichroism spectra . The PPiase denatured in 6 M guanidine-HCl showed fully restored native conformation, as checked by these methods, although renatured PPiase gave a trough in the 280 nm region of slightly less magnitude than that of PPiase . On the other hand, PPiase denatured in 8 M urea showed restored enzymatic activity, but restoration of its conformation was incomplete as compared to PPiase denatured in 6 M guanidine-HCl . PPiase renatured from material denatured in lower denaturant concentrations, such as 4 M urea and 1.5 M guanidine-HCl, had quite a different conformation from the native enzyme as judged from CD spectra, N-bromosuccinimide oxidation and fluorescence spectra . Differences in PPiases denatured in urea and guanidine-HCl were discussed in connection with the possible modification of amino groups in PPiase by cyanate ions. Hoppe Seylers Z Physiol Chem, 1975 Nov, 356(11), 1663 - 9 Subunit structure of 6-phosphofructokinase from brewers' yeast; Tamaki N et al.; An analysis of 6-phosphofructokinase from brewers' yeast in the presence of sodium dodecylsulfate reveals the occurrence of four components with the following molecular weights: alpha = 140000, beta = 130000, and alpha' = 92000, beta' = 87000 . It was found that the alpha- and beta-components can be converted to the alpha' and beta' components by treatment of the native preparation with hyaluronidase . A comparison of the molecular weight obtained by ultracentrifugation and gel filtration with the results obtained by dodecylsulfate electrophoresis after treatment with hyaluronidase reveals that the alpha' and beta' components are the smallest molecular structures obtained upon dissociation of the native enzyme . The mechanism of action of hyaluronidase suggests a desensitization of the alpha and beta components of the enzyme towards dodecylsulfate . Thus, in the absence of hyaluronidase treatment; only an apparent molecular weight for the alpha and beta component is obtained . The analysis indicates that the native enzyme might be composed of four different subunits with an alpha, beta, alpha' and beta' configuration . It is not excluded that the native enzyme consists only of alpha- and beta-chains. Mutat Res, 1975 Nov, 30(2), 191 - 8 Genetic activity of niridazole in yeast; Shahin MM; Niridazole, one of several drugs presently known to be of value in the treatment of human schistosomiasis, was tested for its activity in inducing mitotic recombination in yeast . It was found that niridazole is genetically active when the treatment of yeast cells is performed in a rich medium (YPG-medium) under growing conditions, but not when treatment is carried out in a non-nutrient suspension (phosphate buffer) . The data suggest that niridazole might be converted to an active compound by yeast metabolism . The results of the experiments with niridazole in the non-nutrient medium were compared with those of AF-2 and SQ18, 506, two agents which have been shown to be genetically active in the present assay system. Biochim Biophys Acta, 1975 Oct 20, 405(2), 482 - 91 External yeast beta-fructosidase . The role of tryptophyl residues in catalysis; Leskovac V et al.; 1 . In native invertase at pH 4.6, 23 out of a total of 34 tryptophyl residues are "exposed" to oxidation with N-bromosuccinimide, the other residues being apparently shielded from the oxidant within the molecule . 2 . Oxidation of 5-6 tryptophyl residues/molecule with N-bromosuccinimide is proportional to the complete inactivation of the enzyme, and appears to be specific for indole chromophore only . The ligand binding and fluorescence measurements indicate that the oxidation of native enzyme, up to 50% inhibition, apparently does not change the conformation and topography of enzymes surface . 3 . Invertase is inhibited by diazonium-1-H-tetrazole . Since tyrosine residues can be excluded by nitration studies as catalytically unimportant, it appears that a mocification of a single histidyl residue/molecule with diazonium-1-H-tetrazole is sufficient to abolish the enzymic activity . However, the absence of inhibition with diethyl pyrocarbonate indicates that the inhibition with diazonium-1-H-tetrazole may be mediated through steric hindrance or other indirect effects . 4 . The absence of inhibition with 2,4-dinitrophenylhydrazine, trinitro benzenesulfonic acid and 5,5'-dithiobis-(2-nitrobenzoate) indicates that the carbonyl groups of the carbohydrate moiety, free amino and -SH groups are not essential for activity. J Membr Biol, 1975 Oct 16, 24(1), 55 - 69 Proton magnetic resonance spectroscopy of promitochondrial membranes from yeast grown under different regimes of lipid supplementation; Austin K et al.; Promitochondrial membranes, prepared from Saccharomyces cerevisiae grown anaerobically under different conditions of lipid supplementation, have been examined by PMR spectroscopy . Promitochondria from cells cultured anaerobically in media containing both unsaturated fatty acid and sterol supplements, or containing unsaturated fatty acid alone, yield high resolution spectra similar to those which are characteristic of aerobic mitochondria . By contrast, promitochondrial membranes from cells grown only with sterol supplementation in order to deplete unsaturated fatty acid and total phospholipid content of the organelles, yielded PMR spectra which were very substantially broadened . These spectra are similar to those obtained with rat liver mitochondria . PMR spectra of promitochondria from each cell type dispersed in trifluoroacetic acid, or of extracted lipids or residual proteins similarly dispersed, were different only in detail . It appears, therefore, that in the native state membranes of unsaturated fatty acid-depleted promitochondria are structurally different from promitochondria of the other two cell types . The difference may be a consequence of altered lipid-to-protein ratios, and thus of changes in the extent of lipid domain formation in the membranes of these organelles. J Membr Biol, 1975 Oct 16, 24(1), 35 - 54 Comparison of membrane organization in mitochondria from yeast and rat liver by nuclear magnetic resonance spectroscopy; Brown LR et al.; Proton magnetic resonance (PMR) and carbon-13 magnetic resonance (CMR) spectra of intact, unsonicated yeast and rat liver motochondria show differences which may be correlated with the composition of the membranes . High resolution PMR and CMR signals in intact yeast mitochondria have been assigned to regions of fluid lipid-lipid interaction on the basis of spectra of extracted lipid and protein, and the temperature dependence of NMR signals from the intact membrane . PMR spectra suggest that about 20% of total yeast phospholipid is in regions where both intramolecular fatty acid chain mobility and lateral diffusion of entire phospholipid molecules are possible . No such regions apear to exist in rat liver mitochondria . For both yeast and rat liver mitochondria, comparison of PMR and CMR spectra suggests that about 50% of phospholipid appears to be in regions where intramolecular fatty acid chain motion is considerable, but lateral diffusion is restricted . The remaining phospholipid appears to have little inter- or intramolecular mobility . Since NMR observation of lipid extracts from membranes indicates that phospholipid-sterol interactions do not account for the spectra of intact mitochondria, these effects are interpreted in terms of extensive lipid-protein interactions. Eur J Biochem, 1975 Oct 15, 58(2), 351 - 7 Phenol hydroxylase from yeast . Sulfhydryl groups in phenol hydroxylase from Trichosporon cutaneum; Neujahr HY et al.; Thiol groups in phenol hydroxylase were measured using two different -SH reagents and amino acid analysis . Stepwise blocking of the -SH groups was correlated with enzyme activity and FAD content . The results indicate that the enzyme contains 16 -SH groups per molecule of Mr 1.48 X 10(5) . At least four -SH groups are not accessible without the use of a denaturing agent . There is seemingly no disulphide bridge . On the whole, the reactivity towards p-hydroxymercuribenzoate is much greater than towards 5,5'-dithio-bis(2-nitrobenzoic acid) . The two reagents seem to have a different specificity with respect to which -SH groups they attack . Either reagent dislocates FAD from the holoenzyme, leaving a characteristic mercaptide derivative of the apoenzyme . Such derivatives were used to prepare the apoenzyme . The -SH groups in the apoenzyme are much more reactive towards 5,5'-dithio-bis(2-nitrobenzoic acid) than the -SH groups in the holoenzyme . The stoichiometry of the reaction with 5,5'-dithio-bis(2-nitrobenzoic acid) indicates that at least 8 -SH groups are located in spatially close pairs . The most reactive pair of all does not appear to be of importance for enzyme activity . The two subsequent -SH pairs are essential for enzyme activity are are involved in FAD attachment . The reactivity of the -SH groups decreases dramatically in the presence of substrate, even at substrate concentrations equivalent to the level of the catalytic sites . The isolated apoenzyme has a tendency to aggregate . A large proportion of -SH groups in such aggregate(s) is buried, especially when EDTA is not used throughout the preparation of the apoenzyme . The aggregates are enzymically inactive. Biochemistry, 1975 Oct 7, 14(20), 4385 - 91 Raman spectra and structure of yeast phenylalanine transfer RNA in the crystalline state and in solution; Chen MC et al.; Laser Raman spectra of yeast phenylalanine transfer RNA have been obtained in solution and in orthorhombic and hexagonal crystals . So far as one can tell from the spectra, which are identical in the two crystal forms, the molecular structure of the tRNA is not altered by differences in molecular packing in these two unit cells . In addition, the spectra of the two crystal forms show the same characteristic Raman frequencies and intensities as those of the tRNA in aqueous solution . Thus the structure of the tRNA molecule appears to be the same in the crystals and in aqueous solution . From the spectroscopic changes that result when Mg2+ ions are removed from the native tRNA, it is concluded that the removal of Mg2+ produces a partial disordering of the ribophosphate backbone of the molecule and a lowering of its melting temperature . The melting is shown to be a complex process in that the vibrations specific for adenine indicate a slightly lower melting temperature and those specific for guanine a slightly higher melting temperature than that of the ribophosphate backbone. Mol Gen Genet, 1975 Oct 3, 140(3), 243 - 52 The mating reaction in yeast . I . A new mutation involved in the determination of mating-type; Blamire J et al.; The isolation and preliminary characterisation of a mutation, not linked to the mating type locus, but which apparently alters the mating type directed sequence of events during sexual conjugation is described . Haploids of the alpha mating type carrying this gene will now mate with other alpha haploids, creating diploids homozygous for the alpha mating type locus . This gene can be carried, but not expressed, in a haploids, however in a/alpha diploids homozygous for this gene mating is now possible with both a and alpha haploids giving either a/a/alpha or a/alpha/alpha triploids . Using these strains mating-deficient mutants have been isolated and preliminary results on their characterisation presented. Radiat Environ Biophys, 1975 Oct 2, 12(3), 241 - 52 Structural specificity in the lethal and mutagenic activity of furocoumarins in yeast cells; Averbeck D et al.; Using monofunctional (Angelicin) and bifunctional furocoumarins (Psoralen and 8 Methoxypsoralen) plus 365 nm light it is shown that both damages, the induced monoadducts and/or crosslinks in DNA, provoke lethal and mutgenic effects in haploid and diploid cells of Saccharomyces cerevisiae . Bifunctional furocoumarins are about 20 times more effective in cell killing than Angelicin . Diploid cells are always more resistant than haploid cells . Dark repair (agar haolding) increases survival . This effect can be at least in part correlated to the release of bound material from DNA in dark repair conditions . Bifunctional psoralens (10 mug/ml) are at least 10-fold more effective in inducing nuclear gene black mutations (his- to HIS+) than Angelicin (10 mug/ml) plus 365 nm light or 254 nm ultraviolet light . In contrast cytoplasmic "petite" (delta-) mutations are about as frequently induced by Angelicin plus 365 nm light as by 254 nm UV light . Bifunctional furocoumarins are less effective . The frequency of cytoplasmic "petite" mutations per survivors decreases during dark repair conditions more efficiently after Angelicin than after Psoralen plus 365 nm light treatment. Arzneimittelforschung, 1975 Oct, 25(10), 1519 - 24 The antipyretic effect of suprofen in rats with yeast-induced fever; Niemegeers CJ et al.; The antipyretic activity of alpha-methyl--4-(2-thienylcarbonyl)benzeneacetic acid (suprofen) was studied in rats with comparable hyperthermia after s.c . injection of brewer's yeast . The lowest dose effectively reducing fever is 5 mg/kg and restoration of normal body temperature is obtained with 40 mg/kg . Hypothermia is not observed even after treatment with 160 mg/kg . The ED50 (with confidence limits), which reduces fever below 39 degrees C in 50% of the animals, at the time of peak hyperthermia is 10.0 (6.6--15.2) mg/kg . ED50's of simultaneously studied reference compounds are 5.7 (3.9--8.3) mg/kg for indometacin, 38 (24--61) mg/kg for tolmetin, 76 (47--121) mg/kg for phenylburazone and 113 (75--170) mg/kg for acetyl-salicylic acid . Two to four times higher doses of these compounds restore normal body temperature but further increase of the dose induces hypothermia, which is particularly pronounced for acetyl-salicylic acid and phenylbutazone . Suprofen is a potent antipyretic agent, devoid of hypothermic activity even at 32 times the lowest effective dose. Folia Vet Lat, 1975 Oct-Dec, 5(4), 515 - 26 {An acute toxicity study with three yeast protein sources in beagle dogs}; Newberne PM et al.; Two yeast proteins produced on oil substrate were found safe and nutritious in growing beagle dogs . Reducing nucleic acids with ammonium hydroxide resulted in renal damage; potassium hydroxide reduced nucleic acids with no ill effects . Changes in processing methods must be adequately monitored. Can J Microbiol, 1975 Oct, 21(10), 1614 - 21 Glycogen--a physiological determinant of yeast flocculation? Patel GB, Ingledew WM. Evidence is provided to extend earlier observations that glycogen and flocculence levels vary concurrently in brewing yeast . The use of glycogen mutants, the alterations of growth conditions specifically to inhibit glycogen storage, and observations on glycogen decreases during endogenous metabolism have verified the above . A mechanism by which glycogen might exert its effect on flocculation is suggested. Can J Microbiol, 1975 Oct, 21(10), 1608 - 13 The relationship of acid-soluble glycogen to yeast flocculation; Patel GB et al.; A relationship between yeast flocculation and intracellular acid-soluble glycogen has been established which has been substantiated using flocculation mutants (mutants with altered capacities to flocculate) as well as a normal strain of Saccharomyces carlsbergensis . Sound evidence exists to implicate physiological differences in carbohydrate metabolism (glycogen storage) to this physical property of brewing significance. Am J Roentgenol Radium Ther Nucl Med, 1975 Oct, 125(2), 365 - 73 Yeast bezoar formation following gastric surgery; Perttala Y et al.; Yeast bezoar seems to be a relatively common late complication after various gastric operations . The incidence of bezoar depends decisively on the nature of the operation . Vagotomy in particular is conducive to the formation of a bezoar . Vagotomy + Billroth I resection proveded the most propitious conditions for the growth of yeast, for every one-half of the patients in this group developed a bezoar . Yeast bezoars usually appear within a year of the operation . The majority disappear during the first follow-up year, many without any therapy . However, in some cases the bezoar was a rather inconvenient late complication of gastric surgery and one that gave symptoms . It is difficult to draw any definite conclusions concerning the effect of therapy on the disappearance of the bezoar . We used gastric lavage and antimycotics as well as substances that increase gastric acidity . There is still no known method of preventing the formation of yeast bezoars . In the present consensus, a change in the acid conditions and disturbed gastric motility postoperatively are conducive to the formation of a bezoar. Proc Soc Exp Biol Med, 1975 Oct, 150(1), 77 - 9 Utilization of yeast polyglutamate folates in man; Grossowicz N et al.; Ingestion by healthy humans of small amounts of polyglutamate folates from yeast, equivalent to 300 mug of monoglutamate folate and containing 30 mug of "free folate," resulted in an appreciable elevation of the serum folate corresponding to 300 mug of synthetic pteroylmonoglutamate (PGA) . Ingestion of higher amounts of polyglutamate folate did not result in higher serum folate elevations than did 300 mug . It is concluded that small amounts of polyglutamate folate from yeast are fully utilized, presumably by deconjugation in the gut prior to absorption . The relative ineffectiveness of larger doses of polyglutamate folates from yeast may be due to limiting conjugase activity in the gut, unfavorable conditions for its activity (such as unsuitable pH) or to an inhibitor of the enzyme present in impure preparations. Eur J Biochem, 1975 Oct 1, 58(1), 51 - 7 Characterization of yeast ribosomal DNA; Retel J et al.; High-molecular-weight yeast ribosomal DNA, purified by preparative Hg2+/Cs2SO4 gradient centrifugation, was characterized using RNA-DNA hybridization, CsC1 gradient analysis and denaturation-renaturation experiments . The following conclusions are drawn from the results of these studies . 1 . 55--60% of the total yeast rDNA is made up of sequences coding for 42-S ribosomal precursor RNA . 2 . The mean length of the 42-S precursor cistrons corresponds to a molecular weight of 6.2 X 10(6) . 3 . The overall G + C content fo yeast rDNA is 42% . On the hand, both the segments coding for the nonribosomal excess RNA of the 42-S precursor and those specifying 26-S and 17-S rRNA have a higher G + C content of 46.9--47.5% . 4 . The 42-S precursor cistrons are closely bound up with sequences rather low in G + C content (34--35%), which account for 40--45% of the total yeast rDNA . In contrast to the multiple 42-S precurosr cistrons which show very little or no base sequence divergence these intervening (A + T)-rich sequences display a considerable heterogeneity in base sequence. Proc Natl Acad Sci U S A, 1975 Oct, 72(10), 3952 - 5 Chitin synthetase zymogen is attached to the yeast plasma membrane; Duran A et al.; Pretreatment of yeast protoplasts with concanavalin A, according to the method used by G . A . Scarborough for Neurospora (J . Biol . Chem . 250, 1106-1111, 1975), reinforced the plasma membranes, and helped to maintain their integrity during subsequent lysis of the protoplasts . After purification by centrifuging on a Renografin density gradient, practically intact membranes were obtained . Previous labeling of the protoplasts with 125I or with {3H}concanavalin A resulted in recovery of the radioactivity in the membrane fraction . The bulk of the chitin synthetase (chitin synthase; UDP-2-acetamido-2-deoxy-D-glucose:chitin 4-beta-acetamidodeoxyglucosyltransferase; EC 2.4.1.16) recovered in the gradient was also found In this fraction; in the zymogen form . About 20% of the activity sedimented in a plasma-membrane-free fraction at lower density . Glutaraldehyde inactivated chitin synthetase when it was added to a lysate, but not when applied to intact protoplasts . It is concluded that chitin synthetase is so oriented in the membrane that it is only accessible from the inside of the cell . These results confirm our previous hypothesis that the chitin synthetase zymogen is associated with the plasma membrane, a basic assumption for the explanation of localized activation of the enzyme and initiation of septum formation. Biophys Chem, 1975 Oct, 3(4), 275 - 89 Kinetics of conformational changes in tRNA Phe (yeast) as studied by the fluorescence of the Y-base and of formycin substituted for the 3'-terminal adenine; Coutts SM et al.; The kinetics of the melting transitions of tRNA Phe (yeast) were followed by the fluorescence of the Y-base and of formycin substituted for the 3'-terminal adenine . As judged from differential UV absorbance melting curves the formycin label had virtually no influence on the conformation of the tRNA . A temperature jump apparatus was modified to allow the simultaneous observation of transmission and fluorescence intensities by two independent optical channels . The design of a temperature jump cell with an all quartz center piece is given . The cell is resistant to temperatures up to 90 degrees C; it provides high optical sensitivity, low stray light intensity and the possibility of measuring fluorescence polarization . The T-jump experiments allowed to discriminate between fast unspecific fluorescence quenching (r less than 5 musec) and slow cooperative conformational changes . In the central part of the temperature range of UV-melting (midpoint temperature 30 degrees C in 0.01 M Na+ and 39 degrees C in 0.03 M Na+, pH 6.8) two resolvable relaxation processes were observed . The corresponding relaxation times were 20 msec and 800 msec at 30 degrees C in 0.01 M Na+, and 4 msec and 120 msec at 39 degrees C in 0.03 M Na+ . The Y-base fluorescence shows both of the relaxation effects, which almost cancel in equilibrium fluorescence melting, because their amplitudes have opposite signs . From this finding the existence of some residual tertiary structure is inferred which persists after the unfolding of the main part of tertiary structure during early melting (midpoint temperature 24 degrees C in 0.03 M Na+) . In the fluorescence signal of the formycin also the two relaxation effects appear . Both of them are connected with a decrease of the fluorescence intensity . From the results a coupled opening of the anticodon and acceptor branches is concluded. J Pediatr, 1975 Oct, 87(4), 524 - 7 Yeast colonization in hospitalized and nonhospitalized children; Marks MI et al.; Data have been accumulated to determine the prevalence of yeast colonization of the skin and digestive tract of hospitalized and nonhospitalized infants and children . There was no difference in the prevalence between hospitalized patients at the time of admission and nonhospitalized children . However, there was a positive correlation of the duration of hospitalization and the prevalence of yeast colonization . There were no correlations of hospitalization with site of colonization, age of the patient, or type of yeast isolated. Eur J Biochem, 1975 Oct 1, 58(1), 193 - 201 Influence of various factors on the recognition specificity of tRNAs by yeast valyl-tRNA synthetase; Bonnet J et al.; Using filtration through nitrocellulose membranes we found that complexes between yeast valyl-tRNA synthetase can easily be detected at low pH and ionic strength with the cognate tRNAVal, but also with several non-cognate tRNAs (tRNAPhe, tRNATyr, tRNAMet and tRNAAsp) . We show here that the amino acid linked to the tRNA has no detectable effect on these interactions . The influence of various factors on the discrimination by the enzyme between the cognate and the non-cognate tRNAs has been studied . An increase in pH or ionic strength leads to a decrease in the same ratio of the affinity constants between the enzyme and the cognate as well as the noncognate tRNA . The addition of organic solvents has little effect on these constant either in the cognate or in the non-cognate systems; the addition of substrates of the aminoacylation reaction has not effect on the ratio between the constants . This similar behaviour suggests that at least part of the specific of non-specific interactions must be identical . On the contrary, magnesium between 1 mM and 50 mM increases the specificity of recognition, showing the importance of slight conformational changes in the tRNA molecule to the specificity of interaction. Proc Natl Acad Sci U S A, 1975 Oct, 72(10), 3829 - 33 Control of oscillating glycolysis of yeast by stochastic, periodic, and steady source of substrate: a model and experimental study; Boiteux A et al.; Type and range of entrainment of glycolytic oscillations by a periodic source of substrate are determined experimentally in yeast extracts . Subharmonic entrainment proves the nonlinear nature of the glycolytic oscillator Random variation of the substrate input yields sustained oscillations of irregular waveform and stable period . The results agree with the predictions of an allosteric model for phosphofructokinase (EC 2.7.1.11; ATP:D-fructose-6-phosphate 1-phosphotransferase), which is the enzyme responsible for periodic operation of glycolysis . A comparison between model and experiment in the case of a constant source of substrate further indicates that the oscillatory dynamics of the glycolytic system can satisfactorily be described by the phosphofructokinase model. J Biochem (Tokyo), 1975 Oct, 78(4), 785 - 94 Studies on the microsomal electron-transport system of anaerobically grown yeast . III . Spectral characterization of cytochrome P-450; Yoshida Y et al.; A carbon monoxide-binding pigment which shows an absorption peak at about 450 nm in the reduced carbon monoxide difference spectrum was purified from the microsomal fraction of yeast grown anaerobically . The spectral characteristics of the pigment were practically identical with those of cytochrome P-450 of hepatic microsomes, especially from polycyclic hydrocarbon-induced animals . The pigment was denatured to P-420, and bound with ethyl isocyanide in the reduced state . Although Type I spectral change was not evident, the pigment showed Type II and modified Type II spectral changes upon binding with some organic compounds, as in the case of hepatic cytochrome P-450 . These observations clearly indicate that the carbon monoxide-binding pigment of yeast microsomes may be designated as cytochrome P-450 of yeast. Mol Gen Genet, 1975 Sep 8, 139(4), 329 - 39 The segregation of mitochondrial genes in yeast . I . Analysis of zygote pedigrees of petite X grande crosses; Forster JL et al.; A large number of spontaneous, cytoplasmic petite mutants from six grande strains of Saccharomyces cerevisiae were crossed to a pair of isogenic tester strains . Suppressivity values were obtained by randomly sampling the diploid progeny from these crosses, and this basis, crosses were broadly categorized as having high, intermediate, or low suppressivity . For each cross, individual zygotes were obtained also . All successive first-generation buds were isolated from the zygotes, and analyzed for the presence of petite genotypes . We found that, though early buds may be mixed, all zygotes eventually produce a succession of buds which have the same genotype--either all petite or all grande . Many more zygotes from crosses in all categories of suppressivity purified to petite than expected from the population values for suppressivity . Reconstruction experiments indicate that most petite mutants may actually generate over 90% petite progeny in a petite X grande cross. Biochemistry, 1975 Aug 26, 14(17), 3794 - 9 Fluorescence detected circular dichroism study of the anticodon loop of yeast tRNAPhe; Turner DH et al.; Fluorescence detected circular dichroism (FDCD) measurements have been used to study the conformations of the anticodon loop of yeast phenylalanine tRNA . To our knowledge this is the first application of fluorescence detected circular dichroism . Much smaller amounts of tRNA are needed for the measurement of FDCD than for the conventionally measured circular dichroism . Furthermore, FDCD is specific for conformational changes near the anticodon loop . The FDCD measurements suggest a transition in the anticodon loop near 20 degrees in 0.01 M MgCl2-0.1 M NaCl (pH 7) . This is followed by a broad transition from 30 to 60 degrees and finally a sharp melting at 75 degrees consistent with the absorbance detected melting of the entire tRNA . Removal of Mg2+ from the tRNA at 1 degrees causes nearly a factor of two decrease in the FDCD near 230 nm . This indicates a decrease in conformational rigidity in the anticodon loop on removal of Mg2+. J Gen Microbiol, 1975 Sep, 90(1), 125 - 32 Numerical analysis and computerized identification of the yeast genera Candida and Torulopsis; Campbell I; Numerical analysis of the published standard descriptions of 104 species of Candida and 48 species of Torulopsis suggested that the number of species should be reduced to 78 and 33 respectively . Four examples are noted of closely matched species differing in ability to assimilate nitrate; these species may be combined as nitrate-variable species . Although the ability to form pseudomycelium is the only important difference between the genera, only three examples were noted of Candida and Torulopsis species sufficiently closely matched to be regarded as synonymous . Close relationships with species of the perfect genera were more common . A system, derived from the results of the analysis, is described for computerized identification of species of both genera. Mikrobiologiia, 1975 Sep-Oct, 44(5), 888 - 92 {Primary distribution of n-alkane through the structures of yeast cells}; Davidova EG et al.; When n-alkane enters the cells as a result of molecular sorption and diffusion, it is distributed within all membrane structures of the cell (microsomes, mitochondria, membranes, vacuoles, cytoplasmic membranes, and cell walls) . Sorption of n-alkane by all these structures in vivo comes at equilibrium after incubation of the cells with n-alkane during 3-4 min . Accumulation of the hydrocarbon in the morphological fractions of the cell depends on its concentration in the incubation medium . Isotherms of the sorption are convex curves . Sorption power, maximum sorption capacity, affinity and strength of the bonds with the hydrocarbon differ among the membrane structures of the cell . The maximum capacity of sorption of n-alkane by the structures does not correlate with the content of lipids and phospholipids in the structures . Sorption of n-alkanes is presumed to depend on the structural organization of lipids in the morphological fractions. J Clin Microbiol, 1975 Sep, 2(3), 206 - 17 Improved auxanographic method for yeast assimilations: a comparison with other approaches; Land GA et al.; An improved pour-plate auxanographic method has been developed for determining the assimilation of 14 different carbohydrates by medically important yeasts . Reduction of a dye incorporated into the agar has been correlated with the growth and carbohydrate assimilation of the yeasts, allowing the speciation of many yeasts within 24 to 48 h . This technique has been found to compare more than favorably with existing yeast assimilation techniques, in terms of rapid identification, total cost, and technician time in preparing and inoculating the plates . The dye pour-plate auxanographic technique provides an easier-to-interpret, rapid, and reproducible method of mycological identification for small clinical laboratories. Biochem J, 1975 Sep, 149(3), 507 - 12 Messenger activity of ribonucleic acid form yeast mitochondria; Eggitt MJ et al.; Total yeast mitochondrial RNA was shown to possess messenger RNA activity when injected into oocytes of the frog Xenopus laevis . The specific polypeptides formed were precipitated by mitochondrial antisera . A comparison was made of the molecular weights of the proteins obtained form this system with those made by mitochondria in vivo in the presence of cycloheximide . No RNA containing poly(A) sequences was detected in yeast mitochondria. Eur J Biochem, 1975 Sep 1, 57(1), 115 - 26 Purification and properties of phosphoglucomutase from Fleischmann's yeast; Daugherty JP et al.; 1 . A procedure has been described for the purification of the major isozyme of yeast phosphoglucomutase of highest known specific activity . 2 . The native enzyme has a molecular weight of about 65400 and was found to be homogeneous as judged by sucrose density gradient centrifugation, gel filtration, electrophoresis on acrylamide gel and ultracentrifugal analysis . In the presence of denaturing agents such as guanidine hydrochloride or sodium dodecyl sulfate, the enzyme dissociated into 32000-molecular-weight subunits . 3 . As isolated, the enzyme has one mole of phosphate bound per mole of enzyme . Preparations incubated with 1.0 mM EDTA in 10 mM citrate buffer, pH 5.5 and dialysed against 10 mM metal-free citrate buffer, pH 5.5, contain no intrinsically bound Zn2+ and were enzymically inactive but fully active in the presence of 5 mM Mg2+ and 84% as active with 0.5 mM Zn2+ . Simultaneous presence of both ions at these concentrations did not enhance activity . Enzyme was completely and irreversibly inactivated by preincubation with Be2+ . Inactive enzyme had one mole of Be2+ bound per mole of enzyme . 4 . Enzyme exhibited "ping-pong" kinetics rather than "random sequential" . Km values for glucose 1-phosphate and for glucose 1,6-bisphosphate were calculated to be 2.34 times 10(-5) M and 2.24 times 10(-6) M, respectively . Rate of enzyme phosphate turnover was studied with rapid-mixing technique . The rates of 32P release from 32P-labeled enzyme and its appearance as glucose 6-{32P}phosphate were comparable and remained unaffected by addition of glucose 1,6-bisphosphate. J Biochem (Tokyo), 1975 Sep, 78(3), 599 - 604 Studies on ribosomal ribonucleic acid from yeast . III . Secondary structure of 18 and 26S yeast ribosomal RNA's and their complex: circular dichroism and infrared analyses; Yanagi K et al.; Circular dichroism (CD) and infrared (IR) spectroscopic analyses were performed of 26 and 18S yeast ribosomal RNA's (rRNA) and their specific complex, 30S RNA . The molecular ellipticity coefficients {thota} of 18, 26, and 30S rRNA's were 2.72, 2.63, and 2.65X10(4) degree-cm2/decimole at 264 nm, respectively . The base-pairing contents of 18, 26, and 30S rna's determined by iC), and 70% (32% AU, 38% GC), respectively . These results suggest that 18 and 26S rRNA have very similar secondary structures, and that 30S rna may have a slightly higher base-pairing content than the estimated sum of those of 18 and 26S rRNA's . The biological significance of this phenomenon is discussed in this report. Prikl Biokhim Mikrobiol, 1975 Sep-Oct, 11(5), 637 - 9 {Activity of certain dehydrogenases in accumulation and continuous-flow culture of paraffin-oxidizing yeast of the genus Candida}; Khokhlenko AF et al.; Lability of NADP- and NAD-dependent glutamate dehydrogenases and malate dehydrogenases has been demonstrated during a change of the physiological activity of yeast Candida guilliermondii in the exponential phase of growth . Variations in the isoenzyme spectrum of the enzymes and total dehydrogenase activity of the yeast has been found during their transition from the accumulative to the continuous cultivation . Changes in the physiological state of yeast during their growth are accompanied by a rearrangement of the isoenzyme spectrum of malate dehydrogenase and glutamate dehydrogenases. J Gen Microbiol, 1975 Sep, 90(1), 13 - 20 Synthesis of yeast wall glucan; Sentandreu R et al.; Saccharomyces cerevisiae was treated with a mixture of toluene and ethanol to make it permeable to small molecules . This treatment unmasked a glucan synthetase activity which was assayed with UDP-{U-14C}glucose . About 60% of the polymer formed was beta-(I leads to 3)glucan . No labelled lipids were detected . The 14C incorporated was recovered in a particulate membrane preparation isolated by differential centrifugation . When the particles themselves were assayed for glucosyl transfer activity none was found . The toluene-treated preparations also catalysed the transfer of mannosyl residues from GDP-mannose to polymeric materials by a process independent of glucosyl transfer. J Biochem (Tokyo), 1975 Sep, 78(3), 555 - 60 Mössbauer effect and electron paramagnetic resonance studies on yeast aconitase; Suzuki Y et al.; Mossbauer effect and electron paramagnetic resonance (EPR) were measured for yeast aconitase {EC 4.2.1.3} purified from the cells of Candida lipolytica (ATCC 200114) . Mossbauer spectra suggested that yeast aconitase nostly contained two high-spin Fe(III) ions in an antiferromagnetically coupled binuclear complex that resembled oxidized 2 Fe ferredoxins, together with a small amount of high-spin Fe(II) . EPR spectra recorded no signal at 77degreesK, but showed a slightly asymmetric signal centered at g=2.0 at 4.2degreesK, presumably due to the small amount of Fe(II) Fe(III) pairs. Mikrobiologiia, 1975 Sep-Oct, 44(5), 874 - 9 {Inorganic pyrophosphate synthesis by the mitochondria of the yeast-like fungus Endomyces magnusii coupled with the work of the respiratory chain}; Mansurova SE et al.; The synthesis of inorganic pyrophosphate by the mitochondria of Endomyces magnusii was found to be coupled with respiration . The mitochondria of E . magnusii can utilize the energy of the phosphoanhydride bond of inorganic pyrophosphate for the synthesis of ATP . The study with inhibitors suggests the participation of inorganic pyrophosphatase and ATPase in this process. Genetics, 1975 Sep, 81(1), 51 - 73 A deletion map of cyc1 mutants and its correspondence to mutationally altered iso-1-cytochromes c of yeast; Sherman F et al.; Mutants arising spontaneously from sporulated cultures of certain strains of yeast, Saccharomyces cerevisiae, contained deletions of the CYC1 gene which controls the primary structure of iso-1-cytochrome c . At least 60 different kinds of deletions were uncovered among the 104 deletions examined and these ranged in length from those encompassing only two adjacent point mutants to those encompassing at least the entire CYC1 gene . X-ray-induced recombination rates of crosses involving these deletions and cyc1 point mutants resulted in the assignment of 211 point mutants to 47 mutational sites and made it possible to unambiguously order 40 of these 47 sites . Except for one mutant, cyc1-15, there was a strict colinear relationship between the deletion map and the positions of 13 sites that were previously determined by amino acid alterations in iso-1-cytochromes c from intragenic revertants. Prikl Biokhim Mikrobiol, 1975 Sep-Oct, 11(5), 640 - 44 {Determination of the relative volume of the incorporations of a lipid nature by Candida guilleirmondii yeast cultured on hydrocarbons}; Kazantsev EN et al.; The paper describes a method for measuring a relative volume of lipid incorporations into yeast Candida guilliermondii cultivated on hydrocarbons . A relative volume of the incorporations (mean ratio of the volume of lipid incorporations to the cell volume expressed as percentage) as compared with the hydrocarbon content in the cells expressed as percentage of the yeast dry weight is given for each yeast sample . A direct correlation between the hydrocarbon content and relative volume of lipid incorporations has been demonstrated . The distribution of lipid incorporations in yeast populations with a different content of hydrocarbons has been studied statistically. J Bacteriol, 1975 Sep, 123(3), 1150 - 6 Proteinase C (carboxypeptidase Y) mutant of yeast; Wolf DH et al.; A mutant of yeast lacking proteinase C (carboxypeptidase Y) activity has been found by using a histochemical stain to screen mutagenized colonies . This defect segregates 2:2 in meiotic tetrads . Cell extracts lacked the esterolytic, amidase, and proteolytic activities associated with proteinase C . The absence of proteinase C does not affect mitotic growth and has no obvious effect on the formation of viable ascospores or meiotic segregation . The mutant grows on peptides known to be cleaved by proteinase C in vitro . This finding is consistent with the idea that other enzymes exist in vivo with overlapping substrate specificities. Arch Microbiol, 1975 Aug 28, 104(3), 271 - 7 Cell wall enzymatic lysis of the yeast form of Pullularia pullulans and wall regeneration by protoplasts; Ramos S et al.; During the process of degradation of the cell wall of the yeast form of Pullularia pullulans by the lytic system of micromonospora chalcea samples were withdrawn at different times and observed under phase contrast and electron microscope . The progressive lysis of the walls reveals a fibrillar component inside the apparently amorphous wall . Freeze etched preparations of cells during the formation and regeneration of protoplasts show that the cellular membrane is split and this method allows the smoot