Brown adipose tissue of developing hamster was characterized by western blotting, enzyme activity measurements and immunoelectron microscopy. During the first postnatal week the tissue contained significant amounts of...
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Brown adipose tissue of developing hamster was characterized by western blotting, enzyme activity measurements and immunoelectron microscopy. During the first postnatal week the tissue contained significant amounts of differentiating mictochondria and comparable quantities of active cytochrome oxidase and ATP synthase. The uncoupling protein appeared on the 7/8th day and its specific content increased 80-times between day 8 and day 17. In parallel, the specific content and activity of cytochrome oxidase increased 3-times but ATP synthase decreased 2-times. The total content of uncoupling protein and of cytochrome oxidase in interscapular brown adipose tissue increased 360- and 11-times, respectively. Analysis of isolated mitochondria showed that the observed differences result mainly from changes of the enzymic equipment of the mitochondrial membrane. During the same interval, propylthiouracil-insensitive ''type II'' thyroxine 5''-deiodinase activity in brown adipose tissue increased 10-times. It was concluded that the thermogenic function of the hamster brown adipose tissue develops after the first postnatal week due to highly differentiated synthesis of mitochondrial proteins leading to replacement of preexisting, uncoupling protein-lacking nonthermogenic mitochondria by thermogenic ones, similarly as shown in brown adipose tissue of the embryonic mouse and rat (Houstek, J., et al. (1988) Biochim. Biophys. Acta 935, 19-25).
Electron microscopy of thin sections and detergent extracted preparations of certain trypanosomatids of the genus Phytomonas revealed the unusual presence in some flagellates of an intracytoplasmic flagellum which app...
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Electron microscopy of thin sections and detergent extracted preparations of certain trypanosomatids of the genus Phytomonas revealed the unusual presence in some flagellates of an intracytoplasmic flagellum which appears as a naked axoneme encircling the nucleus before emerging at the anterior end of the cell. Another feature of these atypical flagellates is the absence of the flagellar pocket normally present in trypanosomatids at the emergence of the flagellum.
Intramembrane position of D+, the unusually stable tyrosine radical in Photosystem II (PS II), has been estimated by analyzing the effect of an electron-spin relaxing agent dysprosium (Dy) on the microwave power satur...
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Intramembrane position of D+, the unusually stable tyrosine radical in Photosystem II (PS II), has been estimated by analyzing the effect of an electron-spin relaxing agent dysprosium (Dy) on the microwave power saturation of the EPR signal of D+. It is shownthat an estimation with an electrostatically neutral complex of Dy with hydroxyEDTA (HEDTA) gives more reliable information on the structural organization of PS II than that with a charged Dy3+ ion or Dy-EDTA- complex. Distance from D+ to the outer surface of PS II was estimated at 36 .ANG. from the data with Dy-HEDTA. The distance to the inner surface was estimated at 28 .ANG. with the three (33, 24 and 18 kDa) peripheral polypeptides associated or at 20 .ANG. without these polypeptides. By comparison of the effect of Dy-HEDTA with those of Dy3+ and Dy-EDTA-, the inner surface newly exposed after the removal of the 24 and 18 kDa polypeptides is shown to be negatively charged and after the removal of the 33 kDa polypeptide to be positively charged.
The fluorescent dye 10-N-nonyl acridine orange (NAO), known as specifically associated with mitochondria, has been reported to have a cytotoxic effect when high doses were applied to cells. Presently, the biochemical ...
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The fluorescent dye 10-N-nonyl acridine orange (NAO), known as specifically associated with mitochondria, has been reported to have a cytotoxic effect when high doses were applied to cells. Presently, the biochemical basis of its toxicity was investigated on isolated rat liver mitochondria. At low concentrations, NAO strongly inhibited state 3 respiration and ATP synthesis. At high concentrations, electron transport, ATP hydrolysis, Pi-transport and adenine nucleotide activities were also decreased. All these inhibitions can be explained by probe-cardiolipin interactions which could induce the collapse of energy conversion and/or the modification of membrane fluidity.
Expression of subunit III of the ATP synthase from spinach chloroplasts in Escherichia coli has been achieved. Although the protein is inserted into the bacterial cytoplasmic membrane, formation of a functional f o co...
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Expression of subunit III of the ATP synthase from spinach chloroplasts in Escherichia coli has been achieved. Although the protein is inserted into the bacterial cytoplasmic membrane, formation of a functional f o complex was not observed.
Reductions in the concentration of retinol (vitamin A) in serum, lung and kidney were observed in rats subjected to inflammation-inducing treatments (turpentine oil injection of thermal injury). At the same time, the ...
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Reductions in the concentration of retinol (vitamin A) in serum, lung and kidney were observed in rats subjected to inflammation-inducing treatments (turpentine oil injection of thermal injury). At the same time, the liver showed an almost normal vitamin A content. feeding of retinol to vitamin A-depleted rats with inflammation revealed that intestinal absorption of retinol was still active in the inflamed state, and the livers of these rats showed good incorporation of retinol. The livers of normal and vitamin A-depleted rats subjected to the inflammatory treatments showed a normal RBP content (retinol-binding protein) and hepatic release of holo-RBP into the serum was not impaired functionally. These results suggest the possibility that the decreases of vitamin A in the lung, serum and kidney may be due primarily to enhanced local consumption of vitamin A related to the inflammation, rather than to a reduced supply of vitamin A from the liver or to decreased intestinal absorption. In bovine serum albumin (BSA)-sensitized rats produced by direct intubation of BSA into the lungs, the level of vitamin A in the lung decreased prior to that in the liver or serum, supporting the hypothesis that the decrease in vitamin A in the inflamed lungs of these rats may be due mainly to the consumption of vitamin A in the lung in response to inflammation.
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