Izvestiia Akademii nauk. Seriia biologicheskaia最新文献

The distribution of fibers of different sizes in the gastrointestinal tract in two species of pikas--Pallas' pika Ochotonapallasi and daurian pika O. dauurica--was studied. It was established that fibers of small-sized fractions dominated in all organs of the digestive tract of both pika species, the proportion of which in the stomach proved to be even higher than in fine-grinding voles. No distinct changes in the composition of the size fractions of fibers from organ to organ were observed in the studied individuals of both species, which may be due to frequent consumption of finely dispersed cecotrophs by pikas, which enrich the primary chewed food with small fibers.

In this paper, we analyzed our own results and published data on the expression of regulatory genes encoding transcription factors Pax6/PAX6, Pitx2/PITX2, Fox1/FOXC1, Prox1/PROX1, Oct4/OCT4, Nanog/NANOG, and TGFβ2 signaling protein during morphogenesis of the cornea in vertebrates. We considered the results obtained for the cornea of model animals, primarily mice, and human fetal cornea. The main possibility of establishing common mechanisms of eye development in vertebrates in health and disease is comparative studies of eye morphogenesis of humans and animal models.

The spatial arrangement of muscles in the oral suckers of six trematode species belonging to five families of the order Paramphistomatida is described. The functional load and adaptive significance of different muscle groups in the suckers themselves and the associated structures--preoral lip and muscular cap--are discussed. Complete section series in three projections have been examined; this demonstrates the presence of previously unnoticed structures, namely, semicircular and diagonal muscles, regulating shape of the oral cavity, and short longitudinal muscles, acting as a sphincter, as well as localization of the largest internal muscles on the sucker lateral sides. It has been shown that the presence of internal longitudinal muscles suggests that the organs in question are closer to the oral suckers of other trematodes rather than to their pharynxes.

An interfaced analysis of change of forage vegetation, nutrition of saigas (Saiga tatarica), and their state in tne steppe regions of Russia is performed. It is noted that the percent of graminoids has increased considerably and the proportion of forbs has decreased in the vegetation of current pastures, which has had a negative impact on the nutrition and state of saigas. It is shown that the lower nutritional value of graminoids has caused a decrease in the digestibility of forage used by saigas and does not provide the physiological requirements of the animals. It is established that modern steppe pastures, where gramineous communities prevail, are of little use or absolutely unsuitable for the stable existence of saiga populations. Only separate dwelling places with an abundance of forbs continue to provide adequate nutrition for saigas and well-being for their local groupings.

The distribution patterns and coenotic confines ofthe epiphytic lichen Lobaria pulmonaria have been studied. The factors limiting the habitat of this rare lichen species in the Kologriv Forest Nature Reserve (southern taiga subzone) have been revealed. It has been shown that L. pulmonaria is attracted to forest areas, which are less affected by humans and characterized by better light conditions than other communities. It has been found that L. pulmonaria is able to colonize trees at various ontogenetic states, beginning from virginal ones.

The frequency of occurrence of the mitotypes (control region, cytochrome b gene, and DN2 gene) has been studied for groups of gray whales feeding and growing along Chukotka Peninsula, Koryak Coast, eastern Kamchatka, and Sakhalin Island. The number of the mitotypes decreased dramatically from the northern waters southwards; however, the dominant mitotypes remained the same. Both mitochondrial lineages known for this species might be found for the whales gathering in the reproductive area along the Californian Coast in accordance with the comparison of the published and original data on the haplotypes of the control region. However, it has also been argued that similar sequences of the control region might be found in different mitochondrial genomes, and the analysis of only this site of mtDNA might lead to incorrect conclusions.

We analyzed data from our studies and other author's works concerning the influence of stress stimuli on the development of neuroendocrine and immune systems. The results of our analysis suggest that "immunological stress" induced by viral or bacterial infection, an unhealthy diet, and the mother's behavior during pregnancy and lactation are significant risk factors for the developing offspring. The brain is the key target for these factors. The continuous effect of stress stimuli during critical periods of brain development induces hyperactivity and increased response of hypothalamic-pituitary-adrenal system. This can increase the risk of the development of psychoneurological, metabolic, immunological, and behavioral disorders and the suppression of reproduction in the offspring. The plasticity of physiological systems helps the developing organism to adapt to the changing environment.

The lipid-lowering, fibrinolytic, and anticoagulant effects of leucine-containing glyprolines, Pro-Gly-Pro-Leu and Leu-Pro-Gly-Pro, were studied in vitro in the blood of patients with disorders of lipid metabolism. The lipid-lowering impact of glyprolines and their ability to reduce the polymerization and to increase the depolymerization of fibrin in human blood were found. Possible mechanisms of lipolytic action of peptides by means of modulation of the lipid-dependent phospholipase A2 were proposed.