[Analysis of fragments of intergenome spacers of human body observed in chromosomes containing no nuclear organization].

Tandem repetitions of rDNA provide so-called nuclear organizations (NOR). On the other hand, rDNA-structures are observed in some NOR chromosomes. It was demonstrated that, in addition to ribosome biogenesis, nucleoli provided a number of functions: cell cycle regulation, stress-induced response, transcription regulation, which often induced cell cascades. The mechanisms of the induction of rDNA segments in NOR chromosomes are obscure and require further research. About 1/3 repetitions are associated with nucleoli and SINE/Alu repetitions, homogeneous repetition, and tandem repetition. Perhaps, relative position of nucleoli and chromosomes may facilitate/prevent interaction of chromosomes with rDNA clusters. The variability of two larger repetitions in the central part of rMGS, LR1, and LR2 similar by -90% and separated by several hundred pairs of bases from each other was studied in our previous works. This work was devoted to the search for the LR1-LR2 segments in other chromosomes, characterization of their terminal tips at rupture points and genome areas of incorporation of the LR1-LR2 segments.

[Differentiation of tortoises of the genera Testudo and Agrionemys (Testudinidae) based on the polymorphism of nuclear and mitochondrial markers].

Based on polymorphism of the 12S rRNA gene and RAPD markers, differentiation of 122 tortoise individuals belonging to the three species of genus Testudo (T. kleinmanni, T. marginata, and T. graeca), six subspecies of T. graeca (T. g. nikolskii, T. g. pallasi, T. g. armeniaca, T. g. zarudnyi, T. g. terrestris, T. g. ibera), and two subspecies of the Central Asian tortoise Agrionenemys horsfieldii (A. h. horsfieldii, A. h. kazakhstanica) was performed. For comparison, 32 known sequences of 12S rRNA gene (392 bp) from tortoises of the two genera inhabiting the territories of Europe, Asia, and Africa were used. In the populations of A. horsfieldii, a total of six haplotypes; including three newly described variants, were identified. In the examined tortoises of the genus Testudo, eleven 12S rRNA haplotypes were identified. One new haplotype was detected in T. kleinmanni. Among the eight subspecies of T. graeca, eight haplotypes were identified, with four newly described ones. The reported RAPD markers generally supported the reconstructions obtained with the use of the mitochondrial marker. Similarly to the 12S rRNA-based reconstructions, two independent clusters included representatives of the two genera, Agrionemys and Testudio. Among the latter, representatives of T. marginata and T. kleinmanni, as well as T. graeca, with high statistical support values, formed two reciprocally monophyletic groups. Compared to the mitochondrial markers, RAPDs more statisticallysignificantly discriminated the sample of T. g. terrestris and the four subspecies, T. g. ibera, T. g. armeniaca, T. g. pallasi, and T. g. nikolskii. In almost all cases except the representatives of T. g. ibera, the representatives of each of four subspecies formed individual subclusters. The geographical haplotype distribution patterns and possible evolutionary scenario of the origin and dispersal of tortoises of the two genera are discussed.

Detection of European Trichobilharzia schistosomes ( T. franki , T. szidati , and T. regenti ) based on novel genome sequences.

The most frequent causative agents of cercarial dermatitis in Europe are the avian schistosomes of the genus Trichobilharzia . They preferably parasitize birds of the Anatidae. Trichobilharzia spp. schistosomes are also able to penetrate mammalian skin, posing a health risk to mammals, including humans. Currently several loci from nuclear and mitochondrial genomes are determined for European species of Trichobilharzia . Among them there is 1 genome sequence, ToSau3A, which is suitable for detection of Trichobilharzia spp. infection in aquatic systems. In the present paper, we used a PCR assay to obtain novel genome sequences from cercariae isolates of 3 European bird schistosome species ( Trichobilharzia franki , Trichobilharzia szidati , and Trichobilharzia regenti ) collected from freshwater ponds in Belorussia and Russia. We applied RAPD-fingerprinting using 1 random primer to differentiate 3 trichobilharzian species and subsequently cloned and sequenced putative species-specific RAPD fragments. One of them (410 bp in length), which was obtained for T. franki , revealed 64% homology with the repeat region of Schistosoma mansoni (GenBank FN357352) and turned out to be suitable for designing a specific primer pair (TR98F and TR98R) to detect 7 novel DNA sequences in the genome of 3 European Trichobilharzia species. The newly designed primer pair was found to be potentially suitable for PCR-based detection of trichobilharzian infection in snails. PCR primers TR98F and TR98R amplified only the DNA isolated from cercariae and sporocysts of 3 trichobilharzian species, but neither the DNA of 3 other digenean species ( Bilharziella polonica , Apatemon sp., and Diplostomum sp.) nor the DNA of uninfected host snails ( Lymnaea stagnalis , Radix auricularia , and Radix ovata ).

[Clonal and population RAPD variation of cercariae obtained from Bucephalus polymorphus sporocysts (Trematoda: Bucephalidae)].

Three arbitrary primers produced 114 RAPD markers for 37 cercariae from nine Bucephalus polymorphus sporocysts obtained from three Dreissena polymorpha mollusks, which were collected in two water reservoirs of the Volga basin. Analysis of the RAPD patterns established a unique genotype for each cercaria. The topology of an UPGMA dendrogram did not reliably differentiate the cercaria according to the corresponding sporocysts. However, three groups of genotypes were isolated and corresponded to the host mollusks, indicating that each cercaria clone had a different genotype set. A within-sporocyst variation made the greatest contribution (53.0%) to the total RAPD diversity, while the contributions of within-host and between-host variations to the total diversity were equal (23.5%). Cercariae isolated from two mollusks of the Rybinsk Water Reservoir were more similar to each other than to cercariae from the geographically distant Gor'kovskoe Water Reservoir. Possible causes and distribution specifics of the observed genetic diversity of B. polymorphus are discussed.

[RAPD variation in Mediterranean turtle Testudo graeca L. (Testudinidae)]. / RAPD-izmanchivost' sredizemnomorskoi cherepakhi Testudo graeca L. (Testudinidae).

The polymerase chain reaction with arbitrary primers (RAPD-PCR) was used to study intraspecific variation in Mediterranean turtle Testudo graeca, which is represented by the Dagestan (T. g. pallasi) and Nikolskii (T. g. nikolskii) subspecies in Russia. To study the phylogenetic relationships, the RAPD variation was also compared in two other T. graeca subspecies (T. g. ibera and T. g. terrestris), two closely related Testudo species (T. kleinmanni and T. marginata), and Central Asian turtle Agrionemys horsfieldii. Parameters of RAPD variation showed that the sample from different geographical regions of Dagestan was more polymorphic and heterogeneous than that from Central Asia. The two samples differed in the mean number of RAPD fragments N (48.761 vs. 40.400), number of polymorphic fragments P (78.7 vs. 32.3), and within-group similarity index APS (0.607 vs. 0.784). In T. g. pallasi, no significant difference in N, P, or APS was observed between samples from different localities of Dagestan or between groups of turtles with four- or five-clawed forelegs. A dendrogram of genetic similarity between the species and subspecies under study contained two clusters, one comprising all A. horsfieldii individuals and the other, all turtles of the genus Testudo. In the latter, T. marginata and T. kleinmanni showed higher similarity to each other than to T. graeca. The four T. graeca subspecies clustered separately from each other with a high reliability, T. g. nikolskii and T. g. ibera (Turkey) being more similar to each other than to T. g. terrestris or T. g. pallasi. The possible causes of the presence of four claws on a foreleg and the relationships among members of the genus Testudo were discussed.