[Organization of ribosomal DNA from the phytoflagellates Astasia longa and Euglena gracilis: comparison of the structure of 19S and 28S rRNA genes].

Restriction maps of Astasia longa and Euglena gracilis var. bacillaris were built and localization of 5.8S, 19S and 28S rRNA genes was established on them by blot-hybridization method.

[Organization of archaebacterial chromosomal material].

The data on the structure of the chromosomal material of archaebacteria are reviewed. The results of comparison of amino acid sequences of archaebacterial chromosomal proteins with their eubacterial and eukaryotic counterparts are presented. The similarity and the difference in the structure and properties of chromosomal material of representatives of three evolutionary domains are discussed.

[Instability of the halophilic archaebacteria genome].

The phenomenon of high genetic variability in the extremely halophilic archaebacterium Hb. salinarium is reviewed. The role of IS elements and homologous recombination in frequent genetic rearrangements in this organism is discussed.

Heterogeneity of small plasmids from halophilic archaea.

Small multicopy plasmids in three strains of halophilic archaea, SB3, GRB, and GN101, were found to be present in a cell as a population of related but not identical sequences. Two types of heterogeneity were observed: macroheterogeneity, represented by two major plasmid sequence versions homologous to each other by 80%, and microheterogeneity, in which individual plasmids differ by one or a few nucleotide substitutions.