Seasonal changes in isoform composition of giant proteins of thick and thin filaments and titin (connectin) phosphorylation level in striated muscles of bears (Ursidae, Mammalia).

Seasonal changes in the isoform composition of thick and thin filament proteins (titin, myosin heavy chains (MyHCs), nebulin), as well as in the phosphorylation level of titin in striated muscles of brown bear (Ursus arctos) and hibernating Himalayan black bear (Ursus thibetanus ussuricus) were studied. We found that the changes that lead to skeletal muscle atrophy in bears during hibernation are not accompanied by a decrease in the content of nebulin and intact titin-1 (T1) isoforms. However, a decrease (2.

[ATP content in cryopreserved sperm of Siberian white cranes Grus leucogeranus (Aves: Gruiformes)].

ATP contents were studied in the native and cryoconserved sperm of Siberian white cranes Grus leucogeranus using bioluminescence analysis. The ATP content in freshly obtained spermatozoa was 12.7 nmol/10(8) cells.

[Production of interspecies hybrid of cranes by artificial insemination with frozen semen].

Studies of artificial insemination of cranes and cryoconservation of their semen have been carried out in the nursery of rare species at the Oka Biosphere Reserve for many years. The criterion of successful cryoconservation of the semen is the obtaining of fertilized eggs after artificial insemination by the thawed semen. An experiment is described on artificial insemination of females of the white-naped crane Grus vipio by the frozen-thawed semen of the Siberian white crane G.

[The long-term storage of spermatozoa and its role in vertebrate fertilization].

A hypothesis according to which the prolonged sperm storage in female sex tracts optimizes the fertilization process, permitting to synchronize an encounter of completely formed fertile spermatozoa and ovule under the most favourable for syngamy conditions is proposed. Spermatozoa in the state of "conservation" are the main source of male gametes under internal fertilization. Synchronization in encounter of gametes is achieved by the action on sperm-storage structures of follicular fluids, which brings about evacuation of a portion of sperm-storage structures to be in time with ovulation: yield, reactivation and advancement of sperm to the site of fertilization.