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.     

Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sections

A method of rapid freezing in supercooled Freon 22 (monochlorodifluoromethane) followed by cryoultramicrotomy is described and shown to yield ultrathin sections in which both the cellular ultrastructure and the distribution of diffusible ions across the cell membrane are preserved and intracellular compartmentalization of diffusabler ions can be quantitated. Quantitative electron probe analysis (Shuman, H., A.V. Somlyo, and A.P. Somlyo. 1976. Ultramicros. 1:317-339.) of freeze-dried ultrathin cryto sections was found to provide a valid measure of the composition of cells and cellular organelles and was used to determine the ionic composition of the in situ terminal cisternae of the sarcoplasmic reticulum (SR), the distribution of CI in skeletal muscle, and the effects of hypertonic solutions on the subcellular composition if striated muscle. There was no evidence of sequestered CI in the terminal cisternae of resting muscles, although calcium (66mmol/kg dry wt +/- 4.6 SE) was detected. The values of [C1](i) determined with small (50-100 nm) diameter probes over cytoplasm excluding organelles over nuclei or terminal cisternae were not significantly different. Mitochondria partially excluded C1, with a cytoplasmic/ mitochondrial Ci ratio of 2.4 +/- 0.88 SD. The elemental concentrations (mmol/kg dry wt +/- SD) of muscle fibers measured with 0.5-9-μm diameter electron probes in normal frog striated muscle were: P, 302 +/- 4.3; S, 189 +/- 2.9;C1, 24 +/- 1.1;K, 404 +/- 4.3, and Mg, 39 +/- 2.1. It is concluded that: (a) in normal muscle the "excess CI" measured with previous bulk chemical analyses and flux studies is not compartmentalized in the SR or in other cellular organelles, and (b) the cytoplasmic C1 in low [K](0) solutions exceeds that predicted by a passive electrochemical distribution. Hypertonic 2.2 X NaCl, 2.5 X sucrose, or 2.2 X Na isethionate produced: (a) swollen vacuoles, frequently paired, adjacent to the Z lines and containing significantly higher than cytoplasmic concentrations of Na and Cl or S (isethionate), but no detectable Ca, and (b) granules of Ca, Mg, and P = approximately (6 Ca + 1 Mg)/6P in the longitudinal SR. It is concluded that hypertonicity produces compartmentalized domains of extracellular solutes within the muscle fibers and translocates Ca into the longitudinal tubules.     

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.     

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

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.