[Interspecific hybridization in the genus Paeonia (Paeoniaceae): polymorphic sites in transcribed spacers of the 45S rRNA genes as indicators of natural and artificial peony hybrids].

The ITS1-5.8S rDNA-ITS2 regions of 33 accessions belonging to 16 species and five natural and garden interspecific hybrids of the genus Paeonia L. were sequenced. Chromatograms of the peony hybrids demonstrated the presence of the signals, corresponding to two different nucleotides at the positions differing in the parents, indicating that in the hybrids, no rDNA isogenization usually occurred, and they preserved rDNA of both parents. Analysis of these polymorphic sites (PS) showed that P. x majkoae was interspecific hybrid between P. tenuifolia and P. caucasica. The ITS of P. hybrida differs from ITS of P. x majkoae in 19 mutations. Because of this, P. x majkoae is definitely not synonymous to P. hybrida. Comparative analysis of ITS 1-5.8S rDNA-ITS2 showed that species diversity in section Paeonia was based on recombination as a result of intraspecific hybridization of three haplotype families. Specifically, haplotypes A, typical of the P. tenuifolia and P. anomala genomes, haplotypes B, typical of P. mlokosewitschii and P. obovata, and haplotypes of family C, currently represented in rDNA of diploid and tetraploid forms of some Caucasian and Mediterranean species. The ITS regions many diploid peonies contain no dimorphic sites, while P. oreogeton, P. cambessedesii, P. rhodia, and P. daurica carry from ten to 17 PS, and supposed to be the interspecific hybrids. Most of the tetraploid peonies contain from six to 18 PS in the ITS regions. These are alloploids with one of the parental genomes similar to that of P. mlokosewitschii (B1), or P. obovata (B3). The second parental genome in P. banatica, P. peregrina, and P. russii is represented by the genome, close to that of P. tenuifolia (A). P. macrophylla, P. mascula, P. coriacea, P. wittmanniana, and P. tomentosa carry genome of series B and genome of series C, which slightly resembles genome A.

[Chromosome maps of trilliaceae: II. A study of the genome composition in polyploid species of the genus Trillium by fluorescence nucleotide base-specific staining of heterochromatic chromosome regions]. / Karty khromosom rastenii semeistva Trilliaceae (II): izuchenie genomnogo sostava poliploidnykh vidov roda Trillium pri pomoshchi fluorestsentnogo nukleotid-spetsificheskogo okrashivaniia geterokhromatinovykh raionov khromosom.

Chromosome banding with nucleotide base-specific fluorochromes chromomycin A3 (CMA) and Hoechst 33258 (H33258) was used to study the karyotypes and to construct cytological maps for diploid Trillium camschatcense (2n = 10), tetraploid T. tschonoskii (2n = 20), hexaploid T. rhombifolium (2n = 30), and a triploid T. camschatcense x T. tschonoskii hybrid (T. x hagae, 2n = 15). With H33258, species- and genome-specific patterns with numerous AT-rich heterochromatin bands were obtained for each of the four forms; CMA revealed a few small, mostly telomeric GC-rich bands. In T. tschonoskii, the two subgenomes were similar to each other and differed from the T. camschatcense genome; on this evidence, the species was considered to be a segmental allotetraploid. In T. x hagae, one T. camschatcense and both T. tschonoskii subgenomes were identified. The subgenomes of T. rhombifolium only partly corresponded to the T. camschatcense and T. tschonoskii genomes, in contrast to the morphologically identical Japanese species T. hagae. This was assumed to indicate that allohexaploids T. rhombifolium and T. hagae originated independently at different times; i.e., their origin is polyphyletic. Based on the chromosome maps, a new nomenclature was proposed for the Trillium genomes examined: K1K1 for T. camschatcense, T1T1T2T2 for T. tschonoskii, T1T1T2T2 for T. x hagae, and K1RK1RT1RT1RT2RT2R for T. rhombifolium.

[Nucleotide composition of the cold-sensitive heterochromatin regions of Paris hainanensis Merrill chromosomes]. / Nukleotidnyi sostav chuvstvitel'nykh k kholodovomu vozdeistviiu geterokhromatinovykh raionov khromosom u Paris hainanensis Merrill.

Cold-induced decondensation of heterochromatic regions (CSR-bands) in Paris hainanensis (= Daiswa hainanensis Merrill Takht.) (2n = 10; 10 + b) was studied. The comparison of CSR-banding patterns with those obtained by nucleotide-specific staining with fluorochromes DAPI and chromomycin A3 demonstrated that low temperatures induced decondensation only of large AT-rich heterochromatic regions. It is suggested that this is characteristic of all plant species.

[Chromosome maps of the plant family Trilliaceae: nucleotide composition of heterochromatin an localization of 18S-26S rRNA-genes of four-leafed paris (Paris quadrifolia L.)]. / Karty khromosom rastenii semeistva Trilliaceae: nukleotidnyi sostav geterokhromatina i lokalizatsiia 18S-26S rRNK-genov parisa chetyrekhlistnogo (Paris quadrifolia L.).

Using nucleotide-specific agents Hoechst 33258, actinomycin D, chromomycin A3, and distamycin A, the Paris quadrifolia L. karyotype, and the location and nucleotide composition of heterochromatic bands were studied. The chromosome ideogram of H33258/AMD and CMA/DA heterochromatic bands was created by an image analysis system with the Videotest-Kario software. By fluorescence in situ hybridization, the 18S and 26S rRNA genes were mapped.

[Chiasma distribution in the lampbrush chromosomes of the chicken Gallus gallus domesticus: hot spots of recombination and their possible role in proper dysjunction of homologous chromosomes at the first meiotic division]. / Raspredelenie khiazm po khromosomam--lampovym shchetkam kuritsy Gallus gallus domesticus: goriachie tochki rekombinatsii i ikh vozmozhnoe znachenie dlia pravil'nogo raskhozhdeniia gomologichnykh khromosom v pervom meioticheskom delenii.

Chiasma distribution in the lambrush chromosomes of the chicken Gallus gallus domesticus was studied. The data of the authors show that the general pattern of chiasmata in the interstitional region of chromosomes corresponds to the Poisson distribution. However, in the telomeric and subtelomeric regions of all chicken macrochromosomes one can see chiasma as a rule. In the half of 140 microchromosomes from 24 different oocytes, there are also the telomeric chiasmata. On the basis of this observation, it may be predicted that there are hot spots of recombination near or into the telomeric GC-rich heterochromatic bands of chicken chromosomes. We suggest that these hot spots of recombination near the telomeres are a necessary facility for not only macrochromosomes but all microchromosomes as well to have at least one chiasma. The constant presence of at least one chiasma in a bivalent in needed for correct disjunction of homologous chromosomes at the first meiotic division.