PHYLOGENETIC-RELATIONSHIPS OF THE BAIKALIAN AULACOSEIRA DIATOMS INFERRED FROM COMPARISON OF PARTIAL 18S RIBOSOMAL-RNA SEQUENCES

Partial (507 bp) sequences of 18S rRNA genes were determined for the B aikalian diatoms Aulacoseira baicalensis (K. Meyer) Simonsen, A. skvor tzowii (Edlund, Stroemer, Taylor), and non-Baikalian A. subarctica (O. Mull.) Haworth. Complex phylogenetic analysis of the data obtained an d of diatoms 18S rDNA sequences from the GenBank showed that A. skvort zowii and A. baicalensis are closely related, monophyletic species wit h the highest, 100% bootstrap support. It follows from these results t hat the two species diverged less than 25 million years ago, i.e., dur ing the Baikal history. In experiments with A. skvortzowii, the amplif ied DNA, contrary to the routine methods, was isolated not from the la boratory culture but from the manually selected 300 cells capable of s pore formation. Such an approach makes it possible to analyze a broade r spectrum of diatoms species which cannot be cultivated in the labora tory.