[Diversity of bacteria at various depths in the southern part of lake Baikal as detected by 16S rRNA sequencing]. / Bioraznoobrazie bakterii na razlichnykh glubinakh iuzhnoi kotloviny ozera Baikal, vyiavlennoe po posledovatel'nostiam 16S rRNK.

Phylogenetic analysis of the bacterial community inhabiting the water of Lake Baikal was performed on the basis of 16S rRNA sequencing. The composition of the bacterial community was shown to vary significantly with depth. Cyanobacteria were dominant species at the surface of the lake. At a moderate depth (400 m), actinomycete relatives were most abundant. At a great depth and near the bottom, the community was composed mainly of proteobacteria and cyanobacteria (the latter are probably brought from the surface layers by vertical near-shore water fluxes). Most of the bacterial 16S rRNA sequences detected exhibited low similarity to those known and formed separate clusters in the phylogenetic tree, which may indicate the endemic nature of the corresponding bacteria.

[Nucleotide sequence of a fragment of the Cottocomephorus grewingki phosphofructokinase gene]. / Nukleotidnaia posledovatel'nost' fragmenta gena fosfofruktokinazy Cottocomephorus grewingki.

The nucleotide sequence of a 208-bp fragment of the pfk gene encoding phosphofructokinase from Baikalian fish Cottocomephorus grewingki (Cottidae family) was determined. The fragment shows the codes of a sequence of 38 amino acid residues and contains a 94-bp intron. The nucleotide sequence of the C. grewingki phosphofructokinase gene and the corresponding amino acid sequence display the maximum homology to phosphofructokinases from rabbit muscles and a rat liver.

[Interaction of Escherichia coli RNA polymerase with oligoribonucleotides, homologous to "10"- and "35"- segments of the SPC promotor of bacterial genes]. / Vzaimodeistvie RNK-polimerazy Escherichia coli s oligoribonukleotidami, gomologichnymi "10;- i "35"- uchastkam SPC-promotora bakterial'nykh genov.

It was shown previously that E. coli RNA polymerase in a highly selective manner recognizes and binds 11-14-mere oligodeoxyribonucleotides related to the "-10" region of the nontranscribed DNA strand of bacterial gene promoters. The oligodeoxyribonucleotides cover the Pribnow box with flanking nucleotides up to the transcription start. These affinity oligodeoxyribonucleotides inhibit competitively the transcription of bacterial DNA carried out by E. coli RNA polymerase. The present work has demonstrated that E. coli RNA polymerase is not capable of binding the oligoribonucleotides homologous to the affinity oligodeoxyribonucleotides related to the "-10" area of the spc promoter, but binds the oligoribonucleotides which are complementary to the latter. The oligoribonucleotides with a high affinity for the E. coli RNA polymerase strongly inhibit transcription of the bacterial DNA. Attachment of alkylating groups to the 5'-ends of the affinity oligodeoxy- and oligoribonucleotides provides their covalent binding to the E. coli RNA polymerase subunits. It was shown that the modified affinity 32P-labelled oligodeoxyribonucleotide is covalently bound to the sigma-subunit while the modified affinity 32P-labelled oligoribonucleotide is covalently bound to the beta'beta-subunits of the E. coli RNA polymerase. It is suggested that the affinity oligoribonucleotides can be transcribed from the non-transcribed DNA strand in the region of the open complex and functions presumably as a primer which is splitted later from the nascent RNA or as a regulator of transcription.