Explore the vast range of titles available.

Data are presented on changes in the activity of the membrane-bound osmoregulatory enzyme Na + /K + -ATPase and lipid composition in the gills of pink salmon Oncorhynchus gorbuscha during spawning migration from the White Sea to the river environment through the estuary. The compensatory reaction of pink salmon in a hypoosmotic environment is accompanied by a decrease in Na + /K + -ATPase activity and a change in the content of phosphatidylserine and polyunsaturated fatty acids (linoleic, eicosapentaenoic and docosahexaenoic). The results obtained indicate that effective osmoregulation in pink salmon during spawning migration from the sea to the river allows the implementation of a reproductive strategy.

The experimental study yielded new data on changes in the activity of Na + /K + -ATPase and the level of cortisol in juvenile pink salmon Oncorhynchus gorbuscha that left the spawning nests (Olkhovka River, White Sea basin) during their transfer from fresh water to sea water (25‰) and back. The development of tolerance to increased salinity in juvenile pink salmon is accompanied by activation of Na + /K + -ATPase after 1 h and 24 h of maintaining in seawater and by cortisol content increase after 1 h of this exposure, followed by a return to the initial level after 24 h. The results obtained indicate the readiness of juvenile pink salmon to downstream migration into the marine environment immediately after leaving spawning nests. With the subsequent transfer of fish from salt water to freshwater after 24 h, the activity of Na + /K + -ATPase and the content of cortisol in them decrease, which may indicate the plasticity of the osmoregulatory reaction of pink salmon smolts.

The estradiol content of muscles during metamorphosis in the daubed shanny (Leptoclinus maculatus) from different fjords of Spitsbergen Island, Svalbard, have been studied using mass spectrometry. The level of estradiol at the L4 larval stage of development is significantly lower than at the L2 stage. Values of this parameter in adults are significantly higher than in post-larvae (stage L5). Variations in the estradiol level during metamorphosis can be associated with the growth stimulation and regulation of the process.

Activation of lysosomal degradation proceßs in nervous tißsue may be neuroprotective. One of the factors that may influence on expreßsion of lysosomal proteinases is the sex hormone, estradiol (E 2 ). In this regard the expreßsion of lysosomal proteinases after intracerebral injection of beta-amyloid peptide (Aβ) was investigated as well as the neuroprotective effect of E 2 in Aβ-induced neurodegeneration. Intracerebral injection of Aβ was shown to cause the significant increase in expression of cathepsin D in rat hippocampus and cerebral cortex. On the background of Aβ intoxication, E 2 treatment resulted in further increase in cathepsin D gene expression in hippocampus region and in its lowering to the control level in cerebral cortex. It was demonstrated for the first time that neuroprotective effect of E 2 may be mediated by cathepsin D up-regulation.

Age-related changes of content of thyroid hormones in the blood serum and of activities of lysosomal proteinases in organs were studied in the arctic fox Alopex lagopus L. in early postnatal ontogenesis. The existence has been shown of a negative correlation between the age changes in the serum thyroxin content and lysosomal proteinase activities in some organs of these animals. The results obtained indicate predominance of anabolic function of thyroid hormones in arctic fox cubs. The problem of anabolic and catabolic effects of thyroid hormones on protein metabolism is discussed.[PUBLICATION ABSTRACT]