[Lampbrush chromosomes of the Japanese quail (Coturnix coturnix japonica): a new version of cytogenetic maps].

Avian oocyte chromosomes are transfomed into giant transcriptionally active lampbrush chromosomes (LBCs) at meiosis 1 diplotene. These chromosomes are a convenient tool for high-resulution cytogenetic analysis. Using differential staining with fluorochromes DAPI and CMA3, we have constructed detailed cytological maps for lampbrush macrochromosomes 1-5 and ZW of the Japanese quail Coturnix coturnix japonica. We also performed a comparative analysis ofmitotic chromosomes and LBCs corresponding to them. We estimated the decondensation coefficient during LBC formation and determined the centromere indices for mitotic and diplotene chromosomes and thus found that different chromosomes and chromosomal regions demonstrate unequal degrees of decondensation.

[Analysis of the structure-functional features of a highly-repeating centromere sequence from the Fringilla coelebs L. (Aves: Passeriformes) genome]. / Analiz strukturno-funktsional'nykh osobennoste vysokopovtoriaiushcheisia tsentromernoi posledovatel;nosti iz genoma Fringilla coelebs L. (Aves: Passeriformes).

A highly repetitive centromeric Fringilla coelebs PstI (FCP) element was cloned and sequenced. The FCP tandem repeats with unit 505 or 506 nt accounted for about 0.9% of the entire genome and had 57% GC. Direct genomic sequencing with FCP-specific primers and ThermoFidelase 2A revealed the consensus sequence and the five most common single-nucleotide polymorphisms (SNPs) for the FCP unit. FCP may be transcribed and may play a role in spatial arrangement of the genome.

[Quantitative characteristics of the differential banding pattern prometaphase chromosomes of the domestic horse (Equus caballus)]. / Kolichestvennaia kharakteristika differentsial'noi ischerchennosti prometafaznykh khromosom domashnei loshadi (Equus caballus).

A high-resolution cytogenetic map (670 bands per haploid set) of RBA-banded chromosomes has been constructed in the domestic horse Equus caballus. The size and distribution of the replication-based R(G)-bands were analyzed using the computer program VideoTest-Karyo. The obtained data were compared to the results of cytogenetic mapping in other mammalian species and human.

[The specific blocks of heterochromatin on metaphase chromosomes of horse and Prjewalski horse detected by in situ digestion with restriction endonucleases]. / Osobye bloki geterokhromatina, vyiavliaemye v metafaznykh khromosomakh domashnei loshadi i loshadi Przheval'skogo v rezul'tate obrabotki chromosom restriktazami in situ.

Restriction endonuclease in situ digestion of metaphase chromosomes gives an opportunity to reveal strips with different structure within GC-rich pericentric heterochromatin of the domestic horse and the wild Przewalski horse. Blocks of heterochromatin, which are insensitive to HaeIII and brightly stained with chromomycin A3 after restriction enzyme digestion, are localized on the border with euchromatin in the majority of chromosomes of Equus caballus and E. przewalskii. In contrast to chromosome 5 of E. caballus, acrocentric chromosomes of E. prezewalskii which are homologous to this chromosome have RE-CMA-blocks. We discuss a possible nature of the specific heterochromatin, which is insensitive to restriction enzyme digestion, and its role in the karyotype evolution.

[Monomers of a satellite sequence of chaffinch (Fringilla coelebs L., Aves: Passeriformes) genome contains short clusters of the TTTAGGG repeat]. / Satellitnaia posledovatel'nost' iz genoma ziablika (Fringilla coelebs L., Aves: Passeriformes), monomery kotoroi soderzhat korotkie klastery povtora TTAGGG.

A novel repeated sequence of chaffinch (Fringilla coelebs) designated as GS was isolated from genomic DNA after in vitro amplification of satellite DNA sequences using GSP-PCR technique. The proportion of this repeat in the chaffinch genome constitutes about 2%. Monomers are 176 to 199 bp in size and contain a short cluster of the TTAGGG telomeric tandem repeat. The oligomer of the telomeric hexanucleotide is flanked by the sequences that are significantly different in different monomers. The GS sequences are organized as tandemly repeated units and located in a number of chromomycin-positive blocks on the long arms of macrochromosomes 1, 2, 3, 5, and 6, as well as on several microchromosomes. The sequences homologous to the GS satellite of chaffinch were not found in the genomes of redwing (Turdus iliacus) and house sparrow (Passer domesticus).

[Analysis of the distribution of ribosomal RNA genes on chromosomes of the domestic horse (Equus caballus) using fluorescent in situ hybridization]. / Analiz raspredeleniia genov ribosomnykh RNK na khromosomakh domashnei loshadi (Equus caballus) s pomoshch'iu fluorestsentnoi in situ gibridizatsii.

Distribution of blocks of ribosomal RNA genes along metaphase chromosomes of 26 horses from five breeds was determined by means of a modified method of fluorescence in situ hybridization (FISH) in combination with simultaneous R- banding. Gene loci coding for rRNA were mapped to the region of secondary constriction on the short arm of chromosome 1, and to the pericentromeric regions of chromosomes 27, 28, and 31. The nucleolar organizer region (NOR) on chromosome 27 was not described earlier. Interindividual and interchromosomal NOR polymorphism was detected With the use of a semiquantitative score estimation of fluorescence hybridization signals.