The nuclear glutathione and its functions

During recent years the nuclear localization of glutathione has been confirmed and this fraction has been quantitatively determined. The nuclear GSH and the enzymes of its metabolism realize independent and important functions. They considerably differ from functions of hyaloplasmic and mitochondrial GSH. Glutathione interacts with regulatory pathways, involved into signal transmission into the nucleus.     

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.     

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.     

Features of the Chorion Egg Structure in Nine Species of Underwing Moths Belonging to the Genus Catocala (Lepidoptera,Erebidae)

Entomological Review - Using scanning electron microscopy (SEM), the fine structure of the egg chorion is described and comparatively analyzed in nine species of Catocala underwing moths.     

Influence of changes in glutathione concentration on body temperature and tolerance to cerebral ischemia

Two compounds that deplete glutathione (buthionine sulfoximine and diethyl maleate) with different mechanisms of action decrease body temperature and increase tolerance to complete global cerebral ischemia, both correlating closely with the glutathione concentration decrease. Glutathione apparently participates in the regulations of these functional parameters. GSH diethyl ester does not influence the latter, though it increases moderately the GSH concentration. Injection of GSH ester into the cerebral ventricles or subcutaneously selectively increases the GSH level in the brain and liver. An influence of the brain on the glutathione system in the liver was revealed. Diethyl maleate and GSH ester increase the activity of glutathione metabolizing enzymes under certain conditions.     

Nature of the ligand bound to uncoupling CSP310 protein

It was shown that, in preparations of winter rye (Secale cereale L.) and winter wheat (Triticum aestivum L.), in proteins immunochemically related to a cold shock protein CSP310, and also in purified CSP310 from winter rye and triticale (Triticosecale X.), nucleic acid was present. Treatments with DNase and RNase showed that this nucleic acid was RNA. This protein-bound RNA was detected in the preparation of constitutively synthesized but not stress-induced protein. Stress-induced CSP310 bound high-molecular RNA in vitro at both 26 and 0°C, but it did not bind DNA. The data obtained permit an assumption that, during low-temperature stress, constitutively synthesized CSP310 with a low uncoupling capacity releases RNA and transits to a stress-induced form with a high uncoupling capacity.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 216–220.Original Russian Text Copyright © 2005 by Kolesnichenko, Tauson, Zykova, Klimenko, Grabelnykh, Pobezhimova.This revised version was published online in April 2005 with a corrected cover date.     

Functioning of a CSP310 stress protein is related to the shunting of electron transfer along the respiratory chain of winter wheat mitochondria

Using three-day-old winter-wheat (Triticum aestivum L.) and six-day-old pea (Pisum sativum L.) seedlings as examples, we studied the effects of inhibitors of the electron transfer chain of plant mitochondria on the uncoupling between oxidation and phosphorylation brought about by the CSP310 stress protein. This uncoupling was inhibited by cyanide and by antibodies against CSP310, but not inhibited by antimycin A. It was shown that, in plant mitochondria, the CSP310 stress protein is involved in the electron transfer via shunting the major cytochrome pathway. In this case, the electron transfer bypasses complex II, ubiquinone, and complex III of the mitochondrial respiratory chain and is realized in the following succession: complex I-CSP310-cytochrome c-complex IV. This electron-transfer pathway was found in winter grass mitochondria during the low-temperature stress and resulted in thermogenesis. It was concluded that CSP310 is a thermogenic system, which is activated in winter grass mitochondria during the low-temperature stress.     

Mechanisms and functions of nonphosphorylating electron transport in respiratory chain of plant mitochondria

Data are raeviewed on mitochondrial systems whose functioning in plants diminishes the efficiency of oxidative phosphorylation. The involvement in this process of alternative oxidase, thermogenin-like uncoupling proteins, a 310 kD stress protein, free fatty acids, and the ADP/ATP antiporter is considered. The role of these systems is discussed with regard to thermogenesis, controlled production of reactive oxygen species, and regulation of bioenergetics and metabolism.