[Molecular Polymorphism of ß-Galactosidase LAC4 Genes in Dairy and Natural Strains of Kluyveromyces Yeasts].

The ability to ferment lactose is a characteristic peculiarity of dairy Kluyveromyces lactis yeasts; the vast majority of other yeast species are not able to assimilate this disaccharide. Molecular polymorphism of LAC4 genes encoding ß-galactosidase controlling lactose fermentation is not well studied, and the published data concern only a single strain (K. lactis var. lactis NRRL Y-1140) isolated from cream in the United States. We studied ß-galactosidase genes in lactose-fermenting К lactis strains isolated from dairy products and natural sources in different regions of the world using molecular karyotyping, Southern hybridization, and sequencing. It was established that the ability to ferment lactose in К. lactis var. lactis dairy yeasts is controlled by at least three polymeric LAC loci with different chromosomal localization: LAC1 (chromosome III), LAC2 (II), and LAC3 (IV). Most of the strains we studied had the LAC2 locus. A comparative analysis of ß-galactosidases of the Kluyveromyces genus yeasts and these enzymes from other yeasts was conducted for the first time. Phylogenetic analysis detected significant differences between the LAC4 proteins of yeasts of the Kluyveromyces genus (K. lactis, К. marxianus, К. aestuarii, К. nonfermentans, К. wickerhamii), Scheffersomyces stipitis, Sugiyamaella lignohabitans, and Debaryomyces hansenii. A correlation between ß-galactosidase sequences and ecological origin (dairy products and natural sources) of Kluyveromyces strains was found. The group of dairy strains is heterogeneous and includes К. lactis var. lactis and К. marxianus yeasts (99.80-100% similarity), which indicates a common origin of their LAC4 genes. Phylogenetic analysis of ß-galactosidases indicates a close genetic relationship of dairy and hospital strains of К. lactis var. lactis and К. marxianus. Clinical isolates are able to ferment lactose and appear to originate from the dairy yeasts.

[Sonographic characteristics of non-traumatic focal hourglass-like nerve constriction]. / Sonograficheskie kharakteristiki netravmaticheskoi fokal'noi konstriktsii nerva po tipu 'pesochnykh chasov'.

AIM: To describe the sonographic phenomenon of the focal 'hourglass-like constriction' of the peripheral nerves (FCPN). MATERIAL AND METHODS: The authors described 7 patients meeting the criteria for the diagnosis of neuralgic amyotrophy with unilateral FCPN identified with ultrasound in 4 cases and detected intraoperatively in 3 cases (preliminary ultrasound was not performed). The US scanner Sonoscape Pro mode gray scale in the transverse and longitudinal scanning, linear probe 8-15 MHz and Logiq9 scanner with elastography were used. RESULTS: FCPN was detected in the single nerve in 4 patients, in two nerves in 2 patients and in 3 nerves in one patient. Among all the nerves involved in the pathological process, the radial nerve and its branches were affected in 73% (8 nerves); the ulnar nerve was involved in 18% (2 nerves) and the musculo-cutaneous nerve in 9%. The length of the constriction of the peripheral nerve did not exceed 1.7 mm. The deformation coefficient (DC) of constriction area was 3.8 to .,9; the change in the elasticity in the form of an increase of DC to 5.9 when compared to the intact portion of the nerve and a decrease in echogenicity were observed in one patient. CONCLUSION: High-resolution ultrasound of the nerve can be an informative method for the diagnosis of idiopathic non-traumatic FCPN mononeuropathy.

[Taxonomic Genetics of Methylotrophic Yeast Genus Komagataella: New Biological Species K. kurtzmanii].

Genetic hybridization analysis revealed that industrially important species Komagataella kurtzmanii has re productive postzygotic isolation from K. pastoris, K. populi, K. phaffii, K. pseudopastoris, and K. ulmi. Therefore, it represents a new biological species of the genus Komagataella. The genetic data are in perfect agree ment with the molecular taxonomy of the genus Komagataella.

New family of pectinase genes PGU1b-PGU3b of the pectinolytic yeast Saccharomyces bayanus var. uvarum.

Using yeast genome databases and literature data, we have conducted a phylogenetic analysis of pectinase PGU genes from Saccharomyces strains assigned to the biological species S. arboricola, S. bayanus (var. uvarum), S. cariocanus, S. cerevisiae, S. kudriavzevii, S. mikatae, S. paradoxus, and hybrid taxon S. pastorianus (syn. S. carlsbergensis). Single PGU genes were observed in all Saccharomyces species, except S. bayanus. The superfamily of divergent PGU genes has been documented in S. bayanus var. uvarum for the first time. Chromosomal localization of new PGU1b, PGU2b, and PGU3b genes in the yeast S. bayanus var. uvarum has been determined by molecular karyotyping and Southern hybridization.

[Invertase Overproduction May Provide for Inulin Fermentation by Selection Strains of Saccharomyces cerevisiae].

In some recent publications, the ability of selection strains of Saccharomyces cerevisiae to ferment inulin was attributed to inulinase activity. The review summarizes the literature data indicating that overproduction of invertase, an enzyme common to S. cerevisiae, may be responsible for this phenomenon.

[Hybrid Sterility of the Yeast Schizosaccharomyces pombe: Genetic Genus and Many Species in statu nascendi?].

A phenomenon of ascospore death was observed in a number of Schizosaccharomyces pombe interstrain hybrids. Meiotic recombination of the control parental auxotrophic markers was, however, observed in a random ascospore analysis. Genetic and molecular biological data indicated existence of at least geographical divergence of the genomes in Sch. pombe populations. Classification of the genus, species, and varieties of these yeasts is discussed.

[Towards Reinstatement of the Yeast Genus Zygowilliopsis Kudriavzev (1960)].

Experimental data on genetic molecular classification and identification of the yeast genus Zygowilliopsis are summarized. The genus is represented by at least five biological species and three varieties: Z. californica: var. californica, var. dimennae, and var. fukushimae. Biogeography, ecology and killer activity of Z. californica yeasts is considered. Heterogeneity of the taxonomic genus Barnettozyma Kurtzman et al. (2008) and the necessity for its revision are discussed.

[Molecular polymorphism of IB-fructosidase SUC genes in the yeast].

SUC gees encoding bea-fructosidase has been investigated in the yeast genus Saccharomyces. We have determined nucleotide sequences of subtelomeric SUC3, SUCS, SUC7, SUC8, SUC9, S UCO10 genes of S. cerevisiae and SUCa gene o:f S. arboricola. Comparisns of nucleotid sequences of all known SUCgenes revealed predominance of transitions C-->T in the third codon position, Which are silent. The amilioacids sequences of p-fructosidases studied have identity of 88-100%.4'Most divergent are SUCa (S.'arboricola) and SUCb (S. bayanus), having amino acid identity.with the other SUCproteins less than 92%. It wasdetermined that accumulation of the polymeric SUC genes takes place in industrial populations of S. cerevisiae, while the other Saccharomyces species (S. arboricola, S.:bayanus, S. cariocanuis, kudriavzevii, S. mikatae and S. paradoxus) each harbor only one SUCgene. Subtelomeric repeats of pructosidase SUCgenes cobetald appear in the genome of S. cerevisiae under the effect of selection in the course of their domestication.

[Finding of dairy yeasts Kluyveromyces lactis var. lactis in natural habitats].

Well-known yeasts Kluyveromyces lactis var. lactis, which are usually associated with dairy prod- ucts, were discovered in nature (in woodland park soil under Impatiens glandulifera Royle plants). Reliable identification of the yeasts was carried out using physiological criteria (lactose and maltose utilization) and molecular markers (nucleotide sequence of the 5.8S-ITS rDNA fragment, pulsed-field electrophoresis, and Southern hybridization of chromosomal DNA with the LAC4 probe). Ecology of KI. lactis var. lactis is discussed.

[Comparative genetics of yeast Saccharomyces cerevisiae: chromosomal translocations carrying the SUC2 marker].

Three different translocations involving chromosome IX have been detected in natural Saccharomyces cerevisiae strains using pulsed-field gel electrophoresis with intact chromosomal DNA and their hybridization with the SUC2 probe. Hybrids of these strains with genetic lines having normal molecular karyotype were shown to have back dislocation of at least marker SUC2 due to crossingover. The significance of the detected translocations is discussed.

Mitochondrial DNA polymorphism of the yeast Saccharomyces bayanus var. uvarum.

Genetic relationships among forty-one strains of Saccharomyces bayanus var. uvarum isolated in different wine regions of Europe and four wild isolates were investigated by restriction analysis (RFLP) of mitochondrial DNA (mtDNA) with four restriction endonucleases, AluI, DdeI, HinfI and RsaI. No clear correlation between origin and source of isolation of S. bayanus var. uvarum strains and their mtDNA restriction profiles was found. On the whole, the mtDNA of S. bayanus var. uvarum is much less polymorphic than that of S. cerevisiae. This observation is in good agreement with results obtained by electrophoretic karyotyping. Unlike wine S cerevisiae, strains of S. bayanus var. uvarum display a low level of chromosome length polymorphism.

[Comparative genetics of yeasts: a novel beta-fructosidase gene SUC8 in Saccharomyces cerevisiae].

Molecular and genetic analyses revealed that the distillers race XII, which is an ancestor of Saccharomyces cerevisiae Peterhof and Gatchina genetic lines, has three polymeric beta-fructosidase genes: SUC2, SUC5, and SUC8. The latter gene located on the X chromosome was identitied in this work for the first time. The presence of the single SUC2 gene in yeasts used in the international project on sequencing of the S. cerevisiae genome is discussed.