The study of interaction between paralogous tandem repeats stellate and suppressor of stellate in the genome of Drosophila melanogaster

Testis-specific expression of tandemly repeated Stellate genes, located in eu- and heterochromatin regions of the X chromosome of Drosophila melanogaster, is suppressed by homologous Suppressor of Stellate repeats located on the Y chromosome. Using transgenic lines, we have demonstrated that three Su(Ste) copies failed to change the expression of the reporter construction carrying the bacterial beta-galactosidase gene under control of the Stellate gene regulatory sequence. Possible mechanisms of the Su(Ste) repeat suppressor activity are discussed.     

Natural polyploidization of some cultured yeast Saccharomyces sensu stricto: auto- and allotetraploidy

Using genetic and flow cytometric analyses, we showed that wine strain S6U is an allotetraploid of S. cerevisiae x S. bayanus. Hybrid constitution of the strain and its meiotic segregants was confirmed by Southern hybridization analysis of their chromosomal DNAs using four S. cerevisiae cloned genes: LYS2 (chr. II), TRK1 (chr. X), ARG4 (chr. VIII), ACT1 (chr. VI) and PCR/RFLP analysis of the MET2 gene (chr. XIV). Monosporic progeny of strain S6U was highly viable in first generation but completely nonviable in the second one. According to the genetic analysis, sherry strain S. cerevisiae SBY 2592 was found to be an autotetraploid heterozygous for homo-heterothallism.     

Importance of S. M. Razumovskií's theories for the vegetation science

Publication of S.M. Razumovsky collection works (including some unknown articles) shows his theoretical legacy for current vegetation science. Concepts of S.M. Razumovsky are in the frame of organismic paradigm. He believed that plant communities and associations are natural and continuum concept is only the result of methodical mistakes. Monoclimax (in the meaning of F. Clements) was considered by Razumovsky as the fundamental low of vegetation. Now these statements are very doubtful, but some of his ideas (succession systems, cenophyllous and cenofobous species, the principle and experience of vegetation regionalisation on the base of floristic criteria) are very useful for current vegetation science.     

The molecular genetic typification of planarians in the genus Bdellocephala (Dendrocoelidae, Tricladida, Turbellaria) from Lake Baikal with an assessment of their species diversity

Baikal planaria from genus Bdellocephala were typified using rDNA locus coding 5'--end domain of 18S ribosome RNA. Five colour forms of 24 possible variants that differ in diapason 0-1.3% of genotype were determined by comparative analysis of nucleotide sequences. The authors use back colour--one of the most variable and typical character in the given group--to collect material for investigation. It allows to minimize the size of investigation sample and at the same time to cover maximum variability of Bdellocephala. One of the positive result of molecular typification of colour forms was a discovery of unique individuals that belong to new species. Karyological analysis of colour forms shows variations in chromosome numbers that divide planaria into 3 groups (2n = 20, 24, 26). Comparative analysis of morphological and ecological characters and karyotypes of some forms united by the same genotype allows to distinguish them as separate species. Criteria of modern phenetic system of Baikal planaria are 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.     

Identification of Zygowillopsis californica strains of various origin by polymerase chain reaction with universal primers]

After reevaluation of the taxonomic position of 27 yeast collection strains of different origin by UP-PCR followed by dot-hybridization, only 22 strains were assigned to the biological species Zygowilliopsis californica (Lodder) Kudriavzev. Four strains were identified as Williopsis suaveolens (Kl?cker) Naumov et al. Universal primers L45 and N21 are recommended for identification of the Z. californica yeasts.     

Molecular genetic characterization of the yeast <Emphasis Type="Italic">Lachancea kluyveri</Emphasis>

A comparative study of Lachancea kluyveri strains isolated in Europe, North America, Japan, and the Russian Far East was performed using restriction analysis, sequencing of non-coding rDNA regions, molecular karyotyping, and the phylogenetic analysis of the α-galactosidase MEL genes. This study showed a close genetic relatedness of these L. kluyveri strains. The chromosomal DNAs of the L. kluyveri strains were found to range in size from 980 to 3100 kb. The haploid number of chromosomes is equal to eight. The IGS2 restriction patterns and single nucleotide substitutions in the ITS1/ITS2 rDNA region correlate neither with geographic origin nor with the source of the strains. The L. kluyveri strains isolated from different sources have a high degree of homology (79–100%) of their MEL genes. The phylogenetic analysis of all of the known α-galactosidases in the “Saccharomyces” clade showed that the MEL genes of the yeasts L. kluyveri, L. cidri, Saccharomyces cerevisiae, S. paradoxus, S. bayanus, and S. mikatae are species specific.