[Investigation of nuclear and mitochondrial DNA polymorphism in closely related species of endemic Baikal sponges].

In order to investigate the phylogenetic relationships among endemic Baikal sponges of the Lubomirskiidae family and to clarify their taxonomy, the sequence variation at the silicatein-encoding gene and the mtDNA intergenic region was examined. Phylogenetic analysis of the silicatein α1 gene exonic regions in six freshwater sponge species revealed considerable interspecific variability of this region. The analysis performed did not support the monophyly of the Lubomirskia and Baikalospongia genera.

[Diversity of polyketide synthase genes (PKS) in metagenomic community of the freshwater sponge].

Screening of metagenomic DNA of microbial community, associated with Baikalian sponge Lubomirskia baicalensis, was made to show the presence of polyketide synthase genes (PKS). PKS enzymatic systems take part in synthesis of a great number of biologically-active substances. Cloning and sequencing of amplified products of the ketosynthase domain section of PKS gene cluster has revealed 15 fragments of PKS genes differing from each other's on 35-65% by aminoacid sequences.

[Diversity of 16S rRNA genes in metagenomic community of the freshwater sponge Lubomirskia baicalensis].

Phylogenetic analysis of the nucleotide sequences of 16S rRNA genes in the metagenomic community of Lubomirskia baicalensis has revealed taxonomic diversity of bacteria associated with the endemic freshwater sponge. Fifty-four operational taxonomic units (OTUs) belonging to six bacterial phyla (Actinobacteria, alpha-Proteobacteria, beta-Proteobacteria, Verrucomicrobia, Bacteroidetes, Cyanobacteria, and Nitrospiracea) have been identified. Actinobacteria, whose representatives are known as antibiotic producers, is the dominant phylum of the community (37%, 20 OTUs).

[Freshwater sponge silicateins: comparison of sequences and exon-intron structure of genes].

Siliceous sponge spicules contain silicateins--proteins taking part in biogenic silica precipitation and determination of the spicule morphological features. The exon-intron structure of four silicatein-alpha isoforms: -alpha1,-alpha2, -alpha3 and -alpha4 from endemic baikalian sponge Lubomirskia baicalensis was studied. For eight sponge species, including both cosmopolitan (Spongilla lacustris, Ephydatia muelleri, E.