Chromatin degradation in the death of thymic lymphocytes induced by radiation or dexamethasone: the necessity for a stage of preliminary proteolysis

Proteolytic activity in a protein fraction of a rat thymocyte nuclear matrix was found to increase 1-2 h after gamma-irradiation or administration of dexamethazone. Cycloheximide did not prevent the observed protease activation. Neither histons nor thymocyte nuclear matrix proteins were subjected to proteolysis after exposure to radiation or the hormone. Such proteolysis inhibitors as phenylmethylsulfonyl fluorine, trasilol, and partly leupeptine inhibited nuclear DNA degradation in irradiated and dexamethazone treated thymus lymphocytes. In all appearance, this effect was not due to Ca/Mg-dependent endonuclease inactivation. The same was observed in the system of autolytic chromatin degradation in isolated thymocyte nuclei.     

Ultrastructural organization of the synapses in ganglia of the hen intestinal nerve under various conditions of its activity

The interneuronal connections in ganglia of the caudal part of the hen intestinal nerve of Remak are presented as axodendritic and axosomatic synapses and symmetric axo-axonal, dendro-dendritic and axodendritic contacts, often forming complicated complexes. Under conditions of preliminary decentralization or under certain disturbances of nervous connections with the intestine, a part of synapses remains, and a part of them degenerates, this demonstrates participation of peripheral afferent neurons in formation of the synaptic apparatus of the ganglia mentioned. The axonal terminals differentiate by composition of the synaptic vesicles: some contain mainly light agranular vesicles, others--a large amount of granular ones. The characteristic peculiarities of the hen intestinal nerve ganglia, in contrast to analogous mammalian ganglia, are abundant axosomatic synapses in some neurons, and presynaptic terminals, containing a large number of granular vesicles.     

Sensitivity to stress in the bivalve Macoma balthica from the most northern (Arctic) to the most southern (French) populations: low sensitivity in Arctic populations because of genetic adaptations?

The stress sensitivity, determined in copper exposureexperiments and in survival in air tests, and thegenetic structure, measured by means of isoenzymeelectrophoresis, were assessed in populations of theBaltic clam Macoma balthica (L.) from itssouthern to its northern distribution limit, in orderto test the hypotheses that near the distributionlimit the clams would be more stress sensitive andwould have a lower genetic variability. Thepopulations in west and north Europe show a stronggenetic resemblance. The populations in the sub-ArcticWhite Sea are genetically slightly different, and showa low stress sensitivity. The populations in theArctic Pechora Sea are genetically very distant fromthe other populations, and show the lowest stresssensitivity. Near the southern distribution limit, inagreement with the hypotheses, genetic variability islow and stress sensitivity high. On the other hand, incontrast to expectation, near the northerndistribution limit, in the populations of the PechoraSea, the genetic variability was higher, thus notreduced, and the stress sensitivity was low comparedto all other populations. Yet, it remains a questionif such is due to gradual physiologicalacclimatization (and ongoing differential selection)or to genetic adaptation.     

Role of immune cytolysis and its thymosin stimulation in experimental influenza

In experiments on C57BL and CC57W mice the acute or chronic course of experimental influenza infection has been shown to correlate with the activity of immune cytolysis. At a low level of the cytolytic activity of T-lymphocytes the prolonged persistence of influenza virus develops. The stimulation of cell-mediated immunity with thymosin prevents the development of chronic influenza infection.     

The antitumor effect of magnetic nanodisks and DNA aptamer conjugates

Here we describe a method of forming large arrays (up to 10⁹ pieces) of free magnetic Ni-nanodisks 50 nm thick coated on both sides with layers of 5 nm thick Au. The antitumor effect of the magnetic nickel gold-coated nanodisks and DNA aptamer conjugates was evaluated in vivo and in vitro. Under the influence of rotating magnetic field, the studied nanodisks can cause the death of Ehrlich ascites carcinoma cells.     

Changes of mitochondrial oxidation and phosphorylation in the testes of white rats under excessive supply of sodium nitrate into the organism

The functional state of mitochondria, obtained from the testicles, after chronic intoxication by sodium nitrate (in a dose of 200 mg/kg during 14; 30 and 90 days) was investigated in experiment on white rats. It was revealed, that in dynamics of changes of mitochondrial oxidation and phosphorylation in the testicles under the excessive supply of sodium nitrate into the organism the determined phases should be marked: on the 14th day of intoxication this is the ascending of rate of respiration, on the 30th and 90th day--separation of the mitochondrial oxidation and ADP phosphorylation. It is supposed, that in pathogenesis of these changes the essential role belongs to nitric oxide production.     

Effect of the protein kinase C inhibitor on changes in Ca(2+) level in pig granulosa cells induced by prolactin

The effect of the PKC inhibitor on Ca2+ responses to prolactin in the pig granulosa cells was studied using fluorescent dye and chlortetracycline. The effect was shown to be connected with activation of the PKC. The Ro 31-8220 increased penetration of extracellular calcium and exit of calcium from intracellular stores. The data obtained suggest an involvement of the PKC in changes of calcium contents in the pig granulosa cells activated by prolactin.     

Prolactin in follicular fluid and intracellular store calcium in follicular cells are related to morphological signs of ovarian follicle atresia in cows: work in progress

It is known that prolactin (PRL) is the third pituitary hormone serving gonadotropic function in mammals. However, its role in the regulation of ovarian folliculogenesis and, in particular, its relationship to follicular atresia as well as the mechanism of its influence on follicular cells are poorly understood. We investigated PRL levels in follicular fluids (FFs) and intracellular store calcium ([Ca2+]is) in cell walls of bovine ovarian follicles with diameters of 10 to 20 mm and their relationship to follicular atresia. Ovarian follicles were categorized on the basis of macroscopic criteria and of microscopic examination of granulosa cell (GC) smears. Prolactin concentrations in FFs were measured by RIA and levels of [Ca2+]is in follicular cells were determined by using the fluorophore chlortetracycline. Compared to atretic follicles, morphologically normal follicles were characterized by higher concentrations of PRL in FFs (P < 0.001) and lower contents of [Ca2+]is in follicular cells (P < 0.01). Furthermore, follicles containing no more than 20% of pycnotic GCs had higher levels of PRL in their fluids than those containing over 40% of pycnotic GCs (P < 0.05). Finally, the direct effect of PRL on [Ca2+]is content in follicular cells was studied in vitro. Compared to control, PRL decreased (P < 0.001) the levels of [Ca2+]is in the cells after 24 h culture of follicular walls from morphologically normal follicles in TCM 199 supplemented by 10% fetal calf serum. Our findings suggest that the decline of PRL concentrations in FFs and the rise of [Ca2+]is contents in follicular cells are related to atresia of large bovine follicles and that there appears to be a relationship between the two biochemical parameters.     

Peculiarities of theophylline and prolactin interaction and calcium fluctuation from intracellular stores of porcine oocytes in the presence of estradiol

Using a fluorescent dye chlortetracycline, a study was made of the effect of estradiol on the interaction of theophylline and prolactin in the course of Ca2+ exit from intracellular stores of pig oocytes, isolated from ovaries at the stage of follicle growth. It is shown that in the presence of estradiol, prolactin does not stimulate Ca2+ exit from intracellular stores of pig oocytes. The action of theophylline similarly does not stimulate Ca2+ exit. Unlike, a joint effect of theophylline and prolactin on pig oocytes in the presence estradiol stimulated Ca2+ exit from intracellular stores of pig oocytes. These data demonstrated the influence of estradiol on theophylline and prolactin stimulated Ca2+ exit from intracellular stores of pig oocytes.