Genome size shifts: karyotype evolution in Crepis section Neglectoides (Asteraceae).

Plant genome size evolution is a very dynamic process: the ancestral genome of angiosperms was initially most likely small, which led to a tendency towards genome increase during evolution. However, findings in several angiosperm lineages demonstrate mechanisms that also led to genome size contraction. Recent molecular investigations on the Asteraceae genus Crepis suggest that several genomic reduction events have occurred during the evolution of the genus. This study focuses on the Mediterranean Crepis sect. Neglectoides, which includes three species with some of the smallest genomes within the whole genus. Crepis neglecta has the largest genome in sect. Neglectoides, approximately twice the size of the two species Crepis cretica and Crepis hellenica. Whereas C. cretica and C. hellencia are more closely related to each other than to C. neglecta the karyotypes of the latter species and C. cretica are similar, while that of C. hellenica differs considerably. Here, the karyotypic organisation of the three species is investigated with fluorescence in-situ hybridisation and studied in a molecular phylogenetic framework based on the nuclear markers Actin, CHR12, CPN60B, GPCR1 and XTH23. Our findings further corroborate the occurrence of genome size contraction in Crepis, and suggest that the difference in genome size between C. neglecta and C. cretica is mostly due to elimination of dispersed repetitive elements, whereas chromosomal reorganisation was involved in the karyotype formation of C. hellenica.

[Clastogenic, aneugenic, pro- and antioxidant properties of some neurotropic preparations].

In experimental and clinical investigations, assessment was made of mutagenous, antimutagenous, pro- and antiradical activity of some neurotropic preparations--cerebrolysin, encephabol (pyritinol), nootropil (piracetam), actovegin and cavinton (vinpocetine). In chemical, fermentative and cellular model systems, cerebrolysin inhibited generation of superoxide anion-radical, nitrogen monoxide and final products of degradation of fatty acids. Other preparations showed both anti- and prooxidant effect. The most pronounced anticlastogenic activity during expriments on C. capillaries had a cerebrolysin. Encephabol had the most prooxidant effect and low anticlastogenic activity. The ability of such preparations as ceredrolysin and encephabol to decrease erythrocyte high level with micronuclei in peripheric blood of patients with infantile cerebral palsy (spastic diplegia) was clinically investigated. The modifying effect of preparations was not univalent: it was cerebrolysin that decreased intensivity of aneu- and clastogenesis in patients in a greater degree than encephabol. A protective effect of these preparations was pronounced on the 10th day in group of the boys, and on the 20th day in the group of the girls.

Biological experiments carried out aboard the biological satellite Cosmos-936.

Experiments to study the effect of weightlessness on the emergence and development of cell organelles and genetic structures were carried out during 18.5 days aboard the biological satellite Cosmos-936. The experiments were conducted on the fruit fly Drosophila melanogaster Orgeon-R. Their purpose was to investigate possible chromosomal aberrations and gene mutations in the sex chromosomes of males and females. The investigations showed that the frequency of mutations in the progeny of specimens exposed to weightlessness did not differ from the controls. The experiments with higher plants were performed on the seedlings of Crepis capillaris and Zea mays grown from seeds aboard the biosatellite. The cytological examination of Crepis capillaris chromosomes demonstrated that there were no structural chromosome changes in the experimental and control variants. Maize seedlings grown in weightlessness and examined later in the laboratory showed that cells of the root meristem cultivated in weightlessness were much larger than the controls. Mitochondria of seedlings exposed to weightlessness were swollen and had a low content of membranous material.