[Comparative morphological and gene systematics analysis of the Proteocephalus thymalli (Cestoda: Proteocephalidae), a parasite of graylings in lakes Hovsogol and Baikal]. / Sravnitel'no-morfologicheskii i genosistematicheskii analiz Proteocephalus thymalii (Cestoda: proteocephalidae)--parazita khariusov is ozer Khubsugul i Baikal.

Results of comparative morphological and gene analyses of the cestode Proteocephalus thymalli, an intestine parasite of the lakes Hovsogol (Thymallus arcticus nigrescens) and Lake Baikal graylings (Thymallus arcticus baicalensis) are presented for the first time. The results indicate that representatives of the P. thymalli from these fishes are really two different species.

[Structure of scolex hooks and genosystematics of Triaenophorus nodulosus (Cestoda: pseudophyllidea) from the Baikal lake]. / Morfologiia kriuch'ev skoleksa i genosistematika Trienophorus nodulosus (Cestoda: pseudophyllidea) iz Baikala.

Data on a hook morphology (in plerocercoid and mature helminths) and gene systematics of Triaenophorus nodulosus from the Baikal Lake are presented for the first time. Sequence analysis of rDNA fragments (5'-end portion of 18S rDNA) yelded 562 nucleotid positions.

[Variation in the nucleotide sequences of a 16S rRNA gene fragment from cyanobacteria from picoplankton from Lake Baika from natural samples and laboratory cultures]. / Raznoobrazie nukleotidnykh posledovatel'nostei fragmenta gena 16S rRNA tsinobakterii pikoplanktona ozera Baikal iz prirodnykh obraztsov i laboratornykh kul'tur.

Nucleotide sequences were determined for the 16S rRNA gene 5T-terminal regions of 29 strains of picoplankton cyanobacteria from the lake Baikal in Russia and four strains from the lake Constance (Bodensee) in Germany. Sequences of a 387-bp region of the gene of cultivated strains designated A, B, C, D, and E had only a few (1-3) substitutions as compared with the 3-27 sequence of the clones obtained earlier by cloning from a pooled sample of Baikalian winter picoplankton. The specific 4-33 sequence obtained earlier from a dominant species of Baikalian picoplankton was not found in cultivated cyanobacteria.

[The molecular genetic typification of planarians in the genus Bdellocephala (Dendrocoelidae, Tricladida, Turbellaria) from Lake Baikal with an assessment of their species diversity]. / Molekuliarno-geneticheskaia tipizatsiia planarii roda Bdellocephala (Dendrocoelidae, Tricladida, Turbellaria) ozera Baikal s otsenkoi vidovogo raznoobraziia.

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.

[The first information on Schistocephalus nemachili (Cestoda: Ligulidae) from the Siberian groundling in the Lake Baikal region]. / Pervye svedeniia o Schistocephalus nemachili (Cestoda: Ligulidae) iz sibirskogo gol'tsa Pribaikal'ia.

Morphological data on Schistocephalus nemachili plerocercoid (a parasite of Nemachilis babatulus) and a nucleotide sequence of its 18S rRNA are presented. Samples were collected from the groundling inhabiting the Isumrudnoe lake (karst lake, belonging to the Lena River basin, 1200 m altitude). Length of plerocercoids 37-70 mm (mean 52.9 mm), width 1.6-7.3 (3.8), number of segments in srobile--229-348 (290). The sequence data on the 5'-terminal major domain of small rRNA of S. nemachili were obtained by mean of polymerase chain reaction and direct sequencing, they displayed 574 base positions. The nucleotide sequence was compared with known Plathelminthes sequences from the EMBL data base to compute data matrix under Juke and Cantor's model (1969). Distance matrix was used for obtaining a similarity dendrogram by Saitou and Nei's method (1987). Comparative analysis showed S. nemachili nucleotide sequence clustering with the cestode sequence (E. granulosus) within the dendrogram containing four trematodes, one cestode and one turbellarian sequences.

[The determination of the species classification of Baikal planarian cocoons found in the stomach of the black grayling (Thymallus arcticus baicalensis) by a comparative analysis of the nucleotide sequences of the ribosomal RNA gene]. / Opredelenie vidovoi prinadlezhnosti obnaruzhennykh v zheludke chernogo khariusa kokonov baikal'skikh planarii putem sravnitel'nogo analiza nukleotidnykh posledovatel'nostei gena ribosomnoi RNK.

Comparative analysis of nucleotide sequences of gene 18S of ribosome RNA was carried out. The results show that the genetic sequences of the given locus could be used as a molecular marker to identify the species of planaria irrespective of ontogenetic stage. The articles deals with problem of specific determination of cocoons of Baikal planaria from the stomach of Baikal black grayling using comparative analysis of nucleotide sequences of ribosome RNA fragments with known sequences determined earlier for Baikal planaria. The cocoons belong to two species of Rimacephalus. The authors discuss also the importance of feeding relationships of planaria and benthophage fish to investigate the biotic factors that influence the evolution of Baikal planaria.

Genetic divergence of Asiatic Bdellocephala (Turbellaria, Tricladida, Paludicola) as revealed by partial 18S rRNA gene sequence comparisons.

Polymerase chain reaction (PCR) and direct sequencing of small ribosomal RNA genes were used for analysis of genetic differences among Asiatic species of freshwater triclad genus Bdellocephala. Representatives of four species and four subspecies of this genus were used to establish homology between nucleotides in the 5'-end portion of small ribosomal RNA gene sequences. Within 552 nucleotide sites of aligned sequences compared, six variable base positions were discovered, dividing Bdellocephala into five different genotypes. Sequence data allow to distinguish two groups of these genotypes. One of them unites species from Kamchatka and Japan, another one unites Baikalian taxa. Agreement between available morphological, cytological and sequence data is discussed.

[Molecular phylogeny of Turbellaria, based on data from comparing the nucleotide sequences of 18S ribosomal RNA genes]. / Molekuliarnaia filogeniia (Turbellaria), osnovannaia na dannykh sravnitel'nogo analiza nukleotidnykh posledovatel'nostei gena 18S ribosomnoi RNK.

Polymerase chain reaction and direct sequencing of the 5'-end region of the 18S ribosomal RNA gene were used to infer phylogenetic relationship among turbellarian flatworms from Lake Baikal. Representatives of 5 orders (Tricladida--10 spp., Lecithoepitheliata--5 spp., Prolecithophora--3 spp., Proseriata and Kalyptorhynchia one for each) were studied; nucleotide sequence of more than 340 nucleotides was determined for each species. Consensus sequence for each order having more than one representative species was determined. Distance matrix and maximum parsimony approaches were applied to infer phylogenies. Bootstrap procedure was used to estimate confidence limits, at the 100% level by bootstrapping, the group of three orders: Kalyptorhynchia, Proseriata and Lecithoepitheliata was found to be monophyletic. However, subsets inside the group had no significant support to be preferred or rejected. Our data do not support traditional systematics which joins two suborders Tricladida and Proseriata into the single order Seriata, and also do not support comparative anatomical data which show close relationship of Lecithoepitheliata and lower Prolecithophora.

Phylogenetic relationships of Baikalian species of Prorhynchidae turbellarian worms as inferred by partial 18S rRNA gene sequence comparisons (preliminary report).

The polymerase chain reaction (PCR) and direct sequencing of RNA genes were applied for phylogenetic relationship analysis among Turbellaria (flatworms). Representatives of 10 species of the genus Geocentrophora (Prorhynchidae family) were used to establish homology between nucleotides in the 5'-end portion of the 18S rRNA gene sequences. Sequence data were subdivided into 3 subsets--unpaired and basepaired (according to rRNA secondary structure) and transversion, including only transversion substitutions--that were independently analyzed to construct phylogenetic trees. Distance matrix and maximum parsimony approaches were applied to infer phylogenies. Trees were examined in terms of morphological taxonomy. The DNA sequences support the taxonomy and systematics of Baikalian flatworms. The hypothesis of Geocentrophora origin in Baikal is discussed.

Molecular cloning and sequencing of omul prolactin cDNA.

We constructed a complementary DNA (cDNA) library from Baikal omul (Coregonus autumnalis migratorius Georgi) pituitary glands. Synthetic oligonucleotide probes corresponding to chum salmon prolactin (PRL) cDNA were used to select the recombinant plasmids carrying the omul PRL gene. The larger insert was sequenced and found to encode a polypeptide of 210 amino acid residues, including a putative signal sequence of 23 amino acids. Nucleotide and predicted amino acid sequence of omul PRL showed high homology with other salmonid PRLs.

[Rapid automated synthesis of polydeoxynucleotides]. / Bystryi avtomaticheskii sintez polidezoksinukleotidov.

A rapid automatic method of synthesis of deoxypolynucleotides from 5'-O-dimethoxytritylnucleoside-3'-H-phosphonates is described. An improved construction of synthesizer "Gene-2" adapted for this method has been developed. The modified scheme of synthesis included detritylation with trifluoroacetic acids in dichloromethane, washing with acetonitrile instead of pyridine--acetonitrile mixture and one-step oxidation with iodine solution in acetic acid and pyridine instead of two-step oxidation in the presence of amines. By means of this method, more then 160 polynucleotides containing 8 to 83 monomers were prepared for various biochemical goals including synthesis of promotor 9(260 bp) of the mouse metallothionein-I gene and of promotor and leader sequence (120 bp) of gene of the E. coli alkaline phosphatase.

[Plasmid vector pSSC1 for cloning synthetic polynucleotides and their regeneration with a unique nucleotide sequence]. / Plazmidnyi vektor pSSC1 dlia klonirovaniia sinteticheskikh polinukleotidov i ikh regeneratsii s unikal'noi nukleotidnoi posledovatel'nost'iu.

For subcloning separate synthetic gene fragments, a plasmid vector pSSC1 was constructed by inserting a synthetic polylinker into plasmid pBR 327 at the EcoRI-PstI sites. There are two FokI and HgaI sites at the ends of this polylinker in the opposite orientation, with the EcoRI and PstI sites between them. DNA fragments cloned at the EcoRI and PstI sites can be regenerated by either FokI or HgaI, the EcoRI and PstI sites being deleted from the cloned sequences. Such fragments have unique cohesive ends that allows their directed ligation into longer DNA (genes).

[Cloning of single-stranded synthetic DNA]. / Klonirovanie odnotsepochechnykh sinteticheskikh DNK.

The method for cloning a single-stranded synthetic DNA with the short complementary oligonucleotides, that form corresponding restriction sites, is proposed. The potency of the method is demonstrated by cloning a single-stranded polynucleotide A (93 nucleotide residues (n. r.] in plasmid vector pBR327. The polynucleotide A includes a leader structure of the human fibroblast interferon gene. Oligonucleotides (IV) (20 n. r.) and (VI) (16 n. r.) were taken as strengthening complements and to create the sticky ends for the restrictases HindIII and EcoRI. 72% of the obtained clones appeared to be hybrid. Four hybrid clones were analyzed, and three of them carried the desirable insertion. The primary structures of these insertions are confirmed by sequencing.