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Giant lampbrush chromosomes, which are characteristic of the diplotene stage of prophase I during avian oogenesis, represent a very promising system for precise physical gene mapping. We applied 35 chicken BAC and 4 PAC clones to both mitotic metaphase chromosomes and meiotic lampbrush chromosomes of chicken (Gallus gallus domesticus) and Japanese quail (Coturnix coturnix japonica). Fluorescence in situ hybridization (FISH) mapping on lampbrush chromosomes allowed us to distinguish closely located probes and revealed gene order more precisely. Our data extended the data earlier obtained using FISH to chicken and quail metaphase chromosomes 1-6 and Z. Extremely low levels of inter-and intra-chromosomal rearrangements in the chicken and Japanese quail were demonstrated again. Moreover, we did not confirm the presence of a pericentric inversion in Japanese quail chromosome 4 as compared to chicken chromosome 4. Twelve BAC clones specific for chicken chromosome 4p and 4q showed the same order in quail as in chicken when FISH was performed on lampbrush chromosomes. The centromeres of chicken and quail chromosomes 4 seem to have formed independently after centric fusion of ancestral chromosome 4 and a microchromosome.

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The Feulgen reaction and the staining of preparations with two DNA-specific fluorochromes, Hoechst 33258 and 4 ′ ,6-diamidino-2-fenilindol (DAPI), were used to study the preservation of DNA in the fossilized leaf and fruit tissues of the Lower Eocene Myrtaceae, Paramyrtacicarpus plurilocularis and Paramyrtaciphyllum agapovii collected in Yakutia (Siberia, Russia). It was shown that chromatin structures of the fossilized plants form stable red-purple complexes with the Schiff's fuchsin sulphuric acid reagent in situ . This coloration is specific for DNA, in particular, for the deoxyribose residues. It means that the cell nuclei of these 53-55 Myr old plants preserve a part of the deoxyribose backbone of DNA molecules. On the other hand, there was no, or only a very weak, staining of the cell nucleus with fluorochromes DAPI or Hoechst 33258, which specifically bind to the double-stranded DNA and do not bind to either the single-stranded DNA or RNA molecules. The stainability of fossil plant cell preparations with alcian blue shows that there are also polysaccharides containing carboxyl groups in the cell walls of fossilized leaf and fruit tissues of the Lower Eocene Myrtaceae.

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In this study, sequence data from the inert nuclear region ITS1‐5.8S rDNA‐ITS2 and the chloroplast region trnL–F, as well as a few morphological characters, are analysed to the relationships among known annual Poa (bluegrasses). It is shown that all taxa from the Poa annua aggregate distinguished by lemma characters and growth form have identical ITS and trnL–trnF sequences, all ITS sequences of this aggregate are the same as thethose of P. supina, and all trnL–trnF sequences are homologous with those of P. infirma. Furthermore, no differences were found between unusual morphotypes of P. supina with short spinules on their panicle branches and typical plants, but Siberian samples were found to have a slightly differentiated trnL–trnF region. These results suggest a hybrid origin of the Asian annual bluegrasses. Their maternal genome is close to that of P. sect. Homalopoa, but their ITS sequences are different. Some ITS sequences from annual Asian bluegrasses are resolved among representatives of P. sect. Stenopoa while for other (morphologically closely similar) species they fall in a clade with representatives of P. sect. Malacanthae. The latter group is distant from P. sect. Ochlopoa and is better treated as a separate section, viz P. sect. Acroleucae. The American annual bluegrasses are heterogeneous and also rather distant from P. sect. Ochlopoa. Poa chapmaniana, a species with cleistogamic flowers, is nested among the basal Subantarctic sections, far away from the taxa with which it has previously been considered related. It is indeed closer to P. sect. Ochlopoa than to other annual American bluegrasses. Thus, the studied annual species in fact belong to four independent evolutionary lines (or six including the separate genus Eremopoa and the Turkish Poa jubata), one of which, Acroleucae, has gone through three reticulation events. As in previous studies, our analysis did not support the generic status of P. sect. Ochlopoa.

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