Na+/K+-ATPase Activity in Smolts of Pink Salmon Oncorhynchus gorbuscha (Walbaum, 1792) from the White Sea Exposed to Fresh,Estuarine, and Sea Water

Doklady Biological Sciences - The Na+/K+-ATPase (NKA) activity in smolts of pink salmon Oncorhynchus gorbuscha (a salmon species introduced in 1959 into the rivers of the Kola Peninsula) was...     

Modulation of Ca2+ dependent protease activity in fish and invertebrates by weak low-frequency magnetic fields

Results of experiments addressing the effects of weak low-frequency magnetic fields on intracellular Ca²⁺ dependent proteinases (calpains) from invertebrates and fish are discussed. Exposure of live animals to weak low-frequency magnetic fields with parameters chosen to induce the resonance of Ca²⁺ ions led to a significant decrease of calpain activity in the animals investigated. The physical factor studied also caused partial loss of activity in preparations of Ca²⁺ dependent proteinases obtained from invertebrates and fish. The phenomenon discovered is in accordance with the interference model of the effect of weak low-frequency magnetic fields on biological objects.     

Calpain system dysregulation in rat brain at beta-amyloid-induced neurodegeneration

Experimental evidence of calcium-dependent proteolysis dysregulation in brain of the murine model of Alzheimer’s disease was obtained. Experimental treatment, consisting of intra-hippocampal injection of amyloid beta-peptide (Aβ_1–40), promoted activation of main calpain forms in murine brain along with a decrease in the content of a natural calpain inhibitor, calpastatin. As a result of a prognostic experiment on the correction of neurodegeneration induced in rats, neuroprotective properties of a steroid hormone estradiol were confirmed and a possible mechanism of the protective effect was suggested. The results allow consideration of both biochemical modifications in protein facilities of a pathology-affected brain and the mechanisms of neurodegeneration and neuroprotection.     

Terahertz radiation influence on number and development dynamics of offspring F1 of fruit fly females under stress

Virgin fruit fly females were stressed by placement into a confined space without food for 2.5 hours. Some flies were subjected to terahertz radiation (0.1–2.2 THz) for the last 30 min. Then females were copulated with males. Offspring F1 from oocytes which were mature or immature at exposure (oviposition in 1–2 or 9–10 days after irradiation) was studied. Stress induces a rejection of the offspring maturation dynamics to imago from external control (offspring of flies which was maintained in standard conditions). In offsping from mature oocytes of irradiated flies the dynamics of male maturation to imago was different from internal control (offspring of stressed unirradiated flies). The number of imago males decreased. The dynamics of female maturation to imago coincides with laboratory control. In offsping from immature oocytes of irradiated flies the dynamics of female and male maturation and the number of flies were not significantly different from the internal control. It was concluded that only mature oocytes are sensitive to THz radiation influence.     

Changes of Blue Mussels Mytilus edulis L. Lipid Composition Under Cadmium and Copper Toxic Effect

The lipid and fatty acid composition of the blue mussels Mytilus edulis L. gills and digestive glands was evaluated after 24 and 72 h of cadmium (Cd) and copper (Cu) exposure. Mussels were exposed to different cadmium (10, 100, and 500 μg/L) and copper (5, 50, and 250 μg/L) concentrations. Similar stress response of predominant membrane phospholipids level as well as polyenoic and non-methylene interrupted (NMI) fatty acids content was observed in mussel gills under both cadmium and copper effects. Increased NMI fatty acids level after 24 h, the metal ions treatment suggests that these acids contribute to the protective response to the membrane oxidative stress caused by accumulation of the metals. The content of cholesterol, some minor membrane phospholipids, and storage lipids (triacylglycerols, TAG) in the mussels’ organs alter significantly under the cadmium and copper effect. A two-step response at the digestive glands TAG level depends on the duration of the cadmium and copper treatments (24 and 72 h) on the mussels. The results demonstrate that Cd and Cu impact has adverse effects on gills and digestive glands lipid and fatty acids composition. The type of observed effects varies with the nature and concentration of the metal ions and depends on the role of the metals in the mussels’ life activity.     

Calcium-dependent proteinases of some invertebrates and fish

In comparative-evolutionary aspect, the experimental data are considered about activity, biochemical properties, and peculiarities of structural organization of proteins of the calpain family in some invertebrates and fish. Peculiarities of calpain-like proteins of invertebrates—the predecessors of calpains of higher animals are revealed. By the example of the studied taxa, there is traced complication of the structural organization and mechanisms of control of the calpain activities, which reflects stages of molecular evolution of the protein family.     

Combination of thymidine and dexamethasone increases the K562 tumor cells sensitivity to human leukocytes cytotoxicity

The influence of the number of differentiating agents on sensitivity of human erythroleukemic cells K562 to human leukocyte-mediated non-MHC-restricted lysis was studied. It has been shown that a 4-day treatment of cells K562 by dexamethasone (1 microM) or phorbol-12-myristate-13-acetate (100 nM) leads to a significant decrease in sensitivity of the treated cells to non-specific lysis mediated by human leukocytes. On the contrary, the treatment of cells K562 by a combination of dexamethasone and thymidine (2 mM) leads to an increased sensitivity of the treated cancer cells to non-specific lysis mediated by the above effector cells, compared with the situation when these cells were treated by dexamethasone only. The treatment of cells K562 by a combination of thymidine and phorbol-12-myristate-13-acetate demonstrates a tendency (P < 0.1) to increase the sensitivity to non-specific lysis mediated by human leukocytes, as compared with the cases, when these cells were treated by phorbol ester only. It has been shown that the changes in K562 cell sensitivity to lytic action of leukocytes, under the chosen incubation time and doses of the used agents, well compare with the changes of erythroid differentiation of the cancer cells in the same conditions.