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.     

The search for proteins with immunochemical affinity to plant stress proteins at cold-adapted endemic Baikal fishes

The search for proteins with immunochemical affinity to plant stress proteins in endemic Baikal fishes shows the presence of proteins, immunochemically related to plant heat-stabile proteins and plant uncoupling protein CSP 310. Western blotting showed that among the native cytoplasmic proteins of endemic Baikal fishes there are proteins immunochemically related to heat-stabile plant proteins with molecular weights about 480, 200-290, 150, 140 and about 90-100kD. SDS-electrophoresis showed the presence of polypeptides with molecular weights 23, 17 and 14kD in all species investigated and an additional 35kD polypeptide in Cottocomephorus grewingki. The search for polypeptides with immunochemical affinity to plant stress uncoupling protein CSP 310 in endemic Baikal fishes shows the presence of a 14kD polypeptide, immunochemically related to it.     

Complex I of winter wheat mitochondria respiratory chain is the most sensitive to uncoupling action of plant stress-related uncoupling protein CSP 310

The influence of stress uncoupling protein CSP 310 on functional stability of different mitochondrial respiratory chain complexes was analysed using various substrates of the tricarboxylic acid cycle. Complex I was the most sensitive to CSP 310 uncoupling action whilst other complexes were more stabile. It is proposed that the key point of CSP 310 uncoupling action is complex I of plant mitochondrial respiratory chain.     

Attenuation of TORC1 signaling delays replicative and oncogenic RAS-induced senescence

Numerous stimuli, including oncogenic signaling, DNA damage or eroded telomeres trigger proliferative arrest, termed cellular senescence. Accumulating evidence suggests that cellular senescence is a potent barrier to tumorigenesis in vivo, however oncogene induced senescence can also promote cellular transformation.^1,2 Several oncogenes, whose overexpression results in cellular senescence, converge on the TOR (target of rapamycin) pathway. We therefore examined whether attenuation of TOR results in delay or reversal of cellular senescence. By using primary human fibroblasts undergoing either replicative or oncogenic RAS-induced senescence, we demonstrated that senescence can be delayed, and some aspects of senescence can be reversed by inhibition of TOR, using either the TOR inhibitor rapamycin or by depletion of TORC1 (TOR Complex 1). Depletion of TORC2 fails to affect the course of replicative or RAS-induced senescence. Overexpression of REDD1 (Regulated in DNA Damage Response and Development), a negative regulator of TORC1, delays the onset of replicative senescence. These results indicate that TORC1 is an integral component of the signaling pathway that mediates cellular senescence.     

Peroxidase as a Component of the Signaling Pathway in Potato Cells during Ring Rot Infection

Changes in the activity of peroxidase, a component of the NADPH oxidase signaling pathway, in potato cells were studied. This activity increased sharply during ring rot pathogenesis. Two mechanisms of peroxidase activation were distinguished. One of them was the enzyme de novo synthesis; it was characteristic of the potato cultivar susceptible to the pathogen. Another mechanism characteristic of the resistant cultivar included not only the enzyme synthesis but also the activation of preexisting enzyme molecules. Bacterial infection and exopolysaccharides secreted by the pathogen induced changes in the pattern of intra- and extracellular peroxidases of the susceptible cultivar. No changes were noted in the peroxidase patterns of the resistant cultivar. A sharp activation of the extracellular peroxidase of R _f 15 occurred in the infected or exopolysaccharide-treated cells of the resistant cultivar.     

Involvement of Reactive Oxygen Species in Plant Mitochondrial Response to Low-Temperature Stress

The review presents data for the generation of the reactive oxygen species (ROS) in mitochondria during low-temperature stress. The relation of lipid peroxidation processes in membranes to the induction of low-temperature stress is demonstrated. The data for the involvement of the mitochondrial uncoupling proteins and the processes of uncoupling oxidation and phosphorylation in the regulation of mitochondrial ROS formation during low-temperature stress are considered.     

Disulfide reductase activity in mouse regenerating liver

Fourteen hours after partial hepatectomy there was a decrease in basal disulfide reductase and glutathione reductase activity in cytosole fraction of proliferating hepatocytes. In nuclear fraction, the activation effect of cAMP and cGMP on the disulfide recovery was replaced by inhibition. Meanwhile the activity of glutathione reductase noticeably increased. Forty-five hours after operation disulfide reductase activity of cytosole appreciably rose during maximal mitotic activity of the regenerating liver. The data obtained provide evidence in favor of the involvement of disulfide reductase enzymes into reparative regeneration of the liver.     

Transplacental effect of urethane on DNA synthesis in mouse embryonal lung tissue during organotypical cultivation

Kinetics of DNA synthesis was estimated by autoradiography in the organ cultures of murine embryonic lung tissue. Strain A mice were taken for this experiment (intact and exposed to transplacental action of urethane--30 mg/g to a pregnant mouse, subcutaneously, once). The explants were examined 1,7, 15 and 21 days after the cultivation. Transplacental urethane inhibited DNA synthesis the first 24 hours. The label index became approximately 3 times less. The next two days it was restored and then stimulated. The maximal label index was noted in the experimental explants on the 7th cultivation day, i.e. on the 8th-10th day after the transplacental action of urethane on the lung tissue in utero. By the 15th cultivation day the label index dropped but was higher than in the intact explants; by the 21st day DNA synthesis in the intact cultures ceased completely, whereas in the experimental animals--it continued.