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S G Inge-Vechtomov

Publications and source records attributed to S G Inge-Vechtomov.

At least 55 records · Page 3Linked to original sources
PubMed1983

Development of breeding stocks of the yeast Saccharomycopsis lipolytica by methods of moderate inbreeding.

Sporulation parameters of genetically labelled strains, derived from a wild strain of the alkane-utilizing yeast Saccharomycopsis lipolytica were improved by a breeding program using brother-sister crosses. Sporulation frequency, the number of four-spored asci and viability of ascospores could be significantly enhanced. To date a number of genetically well-defined strains is available that have good sporulation parameters and show a 1:1 segregation pattern of markers suitable for genetic analysis.

Ascomycota↗
PubMed1983

[Genetic express-test for distinguishing between haploids and autodiploids in the yeast Saccharomyces].

Some originally haploid strains of yeast Peterhof breeding stocks obtained in tetrad analysis of diploids turned out to be spontaneous autodiploids after storage. They produced polyploid hybrids, as shown by tetrad analysis. An express-test for discrimination between haploids and autodiploids, based on the frequency of mitotic homozygotisation for a recessive marker has been developed. It is 10-100 times higher in heterozygous diploids than in duplex triploids. Tester strains bearing selective recessive lys2, sup1 or sup2 marker have been obtained. The hybrids of the tester strains and those to be tested were plated on media selective for mitotic segregants homozygous for lys2 (medium with alpha-aminoadipic acid and lysine) or sup1, sup2 (medium without adenine, while the hybrid was homozygous for ochre nonsense ade1-6 suppressible by either sup1 or sup2); UV-induced mitotic homozygotisation was scored. By our method, we have shown that spontaneous autodiploids constitute 70% of strains under investigation in Peterhof breeding stocks.

Cell Cycle↗
PubMed1982

Ribosomal recessive suppressors cause a respiratory deficiency in yeast Saccharomyces cerevisiae.

Recessive suppressor mutations in yeast Saccharomyces cerevisiae alter a component of the cytoplasmic ribosomes, relaxing the control of translational fidelity. As a consequence ribosomes can misread nonsense codons as amino acids (Surguchov et al. 1980a). The suppressor mutants are often respiratory deficient, being unable to grow on non-fermentable substrates. The study of the cytochrome spectra has revealed that the cytochrome b and aa3 contents were lower in the mutants than in the parent strains. Furthermore, the suppressor mutations often cause hypersensitivity to paromomycin and neomycin on media with a non-fermentable source of carbon. Some of the suppressor mutants exhibited both erythromycin and chloramphenicol-dependent growth on media containing ethanol or glycerol as a sole carbon source. These results suggest that the mutations altering cytoplasmic ribosomes may simultaneously impair the mitochondrial translation. A coupling of cytoplasmic and mitochondrial protein synthesis in yeast cells is proposed. The existence of a common protein component participating both in mitochondrial and cytoplasmic protein synthesis apparatus is discussed.

Cytochromes↗
PubMed1981

Further characterization of recessive suppression in yeast. Isolation of the low-temperature sensitive mutant of Saccharomyces cerevisiae defective in the assembly of 60 S ribosomal subunit.

It has been shown that recessive suppressor mutations in the yeast Saccharomyces cerevisiae may cause sensitivity towards low temperatures (very slow growth or lack of growth at 10 degrees C). One of the sup 1 low temperature sensitive (Lts-) mutants, 26-125A-P-2156, was studied in detail. After a prolonged period of incubation (70 h) under restrictive conditions the protein synthesis apparatus in the mutant cells was irreversibly damaged. In addition, Lts- cells incubated under restrictive conditions synthesize unequal amounts of ribosomal subunits, the level of 60 S subunit being reduced. It has been suggested that the recessive suppression is mediated by a mutation in the gene coding for 60 S subunit component, probably a ribosomal protein. The mutation leads simultaneously to a defect in the assembly of 60 S subunit and to low-temperature sensitive growth of the mutant.

Fungal Proteins↗
PubMed1981

[Mechanism of mutant induction in the ade2 gene of diploid Saccharomyces cerevisiae yeasts by ultraviolet rays].

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

Diploidy↗
PubMed1980

Recessive nonsense-suppression in yeast Saccharomyces cerevisiae: the study of 80 S ribosomes accumulated in suppressor strain under non-permissive conditions.

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

Genes, Recessive↗
PubMed1977

[Multiple mutants of Saccharomyces cerevisiae. IV. Mutability of yeast cultures at different growth stages].

Mutability at different stages of culture growth in liquid media of two yeast strains, which revealed a property of "multiple mutability" and one strain of wild type for this property, was studied. One strain that possessed the property of "multiple mutability" showed at stationary phase a very high frequency of mutability, which reached 3.5%. It was found that multiple mutants arose in both strains, that possessed the property under investigation, at lag- and log-growth phases, and only in one strain -- at the stationary phase of growth. The possible reasons of "multiple mutability" display are discussed.

Mutation↗
PubMed1977

[Multiple mutants of Saccharomyces cerevisiae. III. The identification of the mutational changes that occur].

Localization and molecular nature of mutations in multiple mutants of yeast Sacchromyces cerevisiae were studied. It was found that simultaneous changes in several genes located in more than five linkage groups took place during the arise of multiple mutants after a single UV-irradiation (at a dose of 300 erg/nm2). It was shown that reversions of original nonsense-mutations were due to mutational changes in the same genes and the arise of the forward nonsense-mutations in the other genes took place as a result of base changes in DNA.

Crosses, Genetic↗
PubMed1975

[Dominant nonsense suppressors restricting the killer activity in Saccharomyces cerevisiae].

Dominant suppressors of the first type nonsense mutations, ade1-6, hisX, lys9-A21 and leu2-2, inhibit the killer activity in Peterhoff genetic stocks of Saccharomyces cerevisiae. Phenotypes CN (weak killer at 20 degrees, neutral at 32 degrees) and N (neutral at both temperatures) arising in the presence of the suppressors in killer strains are dominant toward S phenotype and toward K phenotype.

Antibiosis↗