Comparative FISH analysis of C-positive regions of chromosomes of wood mice (Rodentia,Muridae, <Emphasis Type="Italic">Sylvaemus</Emphasis>)

The homology of DNA of C-positive centromeric regions of chromosomes in wood mice of the genus Sylvaemus (S. uralensis, S. fulvipectus, S. sylvaticus, S. flavicollis, and S. ponticus) was estimated for the first time. DNA probes were generated by microdissection from the centromeric regions of individual autosomes of each species, and their fluorescence in situ hybridization (FISH) with metaphase chromosomes of representatives of all studied wood mouse species was carried out. Unlike in the chromosomal forms and races of S. uralensis, changes in the DNA composition of the chromosomal centromeric regions in the wood mouse species of the genus Sylvaemus (including closely related S. flavicollis and S. ponticus) are both quantitative and qualitative. The patterns of FISH signals after in situ hybridization of the microdissection DNA probes with chromosomes of the species involved in the study demonstrate significant differences between C-positive regions of wood mouse chromosomes in the copy number and the level of homology of repetitive sequences as well as in the localization of homologous repetitive sequences. It was shown that C-positive regions of wood mouse chromosomes can contain both homologous and distinct sets of repetitive sequences. Regions enriched with homologous repeats were detected either directly in C-positive regions of individual chromosomes or only on the short arms of acrocentrics, or at the boundary of C-positive and C-negative regions.     

Immunofluorescent analysis of meiotic recombination in the domestic cat

The paper presents the analysis of the frequency, density, and distribution of recombination sites in the male meiosis of the domestic cat (Felis silvestris catus). The study was carried out using immunofluorescent staining of synaptonemal complex (SC) proteins, centromeric proteins and mismatch repair protein MLH1, a reliable marker of crossingover sites. We mapped 2633 sites of crossing over in 1098 individual autosomes. Based on these data, we estimated the total length of the genetic map of the domestic cat to be 2176 centimorgans. Positive correlation between the length of SC and the number of recombination sites common for mammalians was also found in the domestic cat. It was shown that this species was characterized by the highest density of recombination and the lowest interference in mammals.     

Differences in ribosomal DNA distribution on A and B chromosomes between eastern and western populations of the grasshopper Eyprepocnemis plorans plorans

Distribution of ribosomal DNA (rDNA) on standard (A) and supernumerary (B) chromosomes of the grasshopper Eyprepocnemis plorans was analysed in specimens collected in Turkey and Armenia, belonging to the E. p. plorans subspecies, and in South Africa, belonging to the E. p. meridionalis subspecies. The latter individuals showed rDNA loci in chromosomes 9 and 11 only, whereas those from Armenia carried it in chromosomes 9 and 11 or else in chromosomes 9-11, depending on the population. The specimens from Turkey carried it in chromosomes 1, 9-11 and X. A comparison of this pattern with those previously observed in populations from Spain, Morocco, and Greece (belonging to E. p. plorans) suggests the existence of two evolutionary patterns in rDNA chromosome location in A chromosomes of this subspecies: eastern populations showing rDNA restricted to the small (9-11) chromosomes (as in E. p. meridionalis and other closely related taxa within the Eyprepocneminae subfamily) and western populations carrying rDNA in most A chromosomes (Spain) or all of them (Morocco). The intermediate pattern discerned in geographically intermediate populations (in Greece and Turkey), with rDNA also being located on the X chromosome, suggests a possible east-west cline. Additional support for east-west differentiation in the rDNA location pattern comes from the analysis of B chromosomes. In eastern populations, including Daghestan, Armenia, Turkey, and Greece, B chromosomes are composed mostly of rDNA, whereas in western populations (Spain and Morocco) they contain roughly similar amounts of rDNA and a 180-bp tandem repeat (satDNA), the latter being scarce in eastern Bs.     

Effectiveness of chemical mutagenesis in multiple damage to one or both strands of plasmid DNA

Methods for site-directed multiple modification of DNA have been developed and used for modification of either one or two strands of plasmid DNA. Plasmid DNAs modified in the region of the tet gene were transformed into Escherichia coli cells and Tet colonies were screened. It was shown that multiple lesions in one DNA strand performed using either N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or sodium bisulfite were effectively repaired in the cell by error-free mechanism. In contrast, modification of two DNA strands led to induction of mutations. The efficiency of mutagenesis in the case of modification of a local region of one DNA strand with sodium bisulfite and modification of the other strand with MNNG was 1.1-7.9%. Mutations were analysed by restriction mapping and sequencing. All of them were G----A transitions.     

Visualization of Chromosome Territories in Interphase Nuclei of Ovarian Nurse Cells in <Emphasis Type="Italic">Calliphora erythrocephala</Emphasis> Mg. (Diptera: Calliphoridae)

Analysis of localization of chromosomes 2, 3, and 6 of Calliphora erythrocephala Mg. in ovarian nurse cell nuclei with different chromatin structure has shown that the regions of DNA probe hybridization reduced with increasing chromatin compaction. Hybridization of DNA probes of chromosomes 3 and 6 to secondary reticular nuclei demonstrated that chromosomes retain their territories in the nuclei when the chromatin acquires a reticular structure. These results suggest regular organization of the chromosomal apparatus at all stages of the endomitotic cycle, including the stage of highly polyploid reticular nuclei. FISH of DNA probe of the chromosome 2 telomeric region to secondary reticular nuclei revealed a peripheral distribution of the signal. Zones of more intensive DNA probe hybridization have been distinguished. These zones probably are the regions of accumulation of telomeric and (or) centromeric chromosome regions.     

Interaction of electrophilic alkylating agents with nucleophilic sites of mitochondria]

The electrophilic alkylating agents having different numbers of electrophilic groups with nucleophilic sites of mitochondria were studied. Bifunctional compounds were found to modify the structure of mitochondria so that some of the sulfhydryl groups become inaccessible for titrating ions of Ag+. Monofunctional agents caused no changes in the number of determinable sulfhydryl groups and prevented the effect of bifunctional compounds. The linkage formed between the electrophilic residue and the nucleophilic site is stable in the absence of electron transport. During the transport of electrons in the respiratory chain the linkage becomes labile and the electrophilic residue chips off. A scheme of interaction of electrophilic alkylating agents with nucleophilic sites of mitochondria is proposed.     

Distribution of repetitive DNA sequences in chromosomes of five opisthorchid species (Trematoda, Opisthorchiidae)

Genomes of opisthorchid species are characterized by small size, suggesting a reduced amount of repetitive DNA in their genomes. Distribution of repetitive DNA sequences in the chromosomes of five species of the family Opisthorchiidae (Opisthorchis felineus 2n = 14 (Rivolta, 1884), Opisthorchis viverrini 2n = 12 (Poirier, 1886), Metorchis xanthosomus 2n = 14 (Creplin, 1846), Metorchis bilis 2n = 14 (Braun, 1890), Clonorchis sinensis 2n = 14 (Cobbold, 1875)) was studied with C- and AgNOR-banding, generation of microdissected DNA probes from individual chromosomes and fluorescent in situ hybridization on mitotic and meiotic chromosomes. Small-sized C-bands were discovered in pericentric regions of chromosomes. Ag-NOR staining of opisthorchid chromosomes and FISH with ribosomal DNA probe showed that karyotypes of all studied species were characterized by the only nucleolus organizer region in one of small chromosomes. The generation of DNA probes from chromosomes 1 and 2 of O. felineus and M. xanthosomus was performed with chromosome microdissection followed by DOP-PCR. FISH of obtained microdissected DNA probes on chromosomes of these species revealed chromosome specific DNA repeats in pericentric C-bands. It was also shown that microdissected DNA probes generated from chromosomes could be used as the Whole Chromosome Painting Probes without suppression of repetitive DNA hybridization. Chromosome painting using microdissected chromosome specific DNA probes showed the overall repeat distribution in opisthorchid chromosomes.     

Clusters of Repetitive DNA Sequences in Chromosomes of Voles of the Subgenus Microtus (Microtus,Arvicolidae)

Russian Journal of Genetics - The study is focused on the analysis of the mechanisms underlying the formation and distribution of repeat clusters in mammalian chromosomes, as exemplified by a group...     

Decision of mathematical logical tasks in sensory enriched environment (classical music)

The time of a decision of mathematical logical tasks (MLT) was decreased during classical musical accompaniment (power 35 and 65 dB). Music 85 dB did not influence on the process of decision of MLT. Decision without the musical accompaniment led to increasing of coherent function values in beta1, beta2, gamma frequency ranges in EEG of occipital areas with prevalence in a left hemisphere. A coherence of potentials was decreased in EEG of frontal cortex. Music decreasing of making-decision time enhanced left-sided EEG asymmetry The intrahemispheric and the interhemispheric coherences of frontal cortex were increased during the decision of MLT accompanied by music. Using of musical accompaniment 85 dB produced a right-side asymmetry in EEG and formed a focus of coherent connections in EEG of temporal area of a right hemisphere.