Tsuyoshi Takahashi

Publications (2)6.46 Total impact

• Article: Effect of Tobacco Mosaic Virus Infection on Amino Acid Incorporation into Isolated Mitochondria from Tobacco Leaves

  Tsuyoshi Takahashi, Tokuzo Hirai
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  ABSTRACT: Mitochondria isolated from tobacco leaves incorporated 14C-leucine into the protein and the rate was enhanced by tobacco mosaic virus (TMV) infection as compared with noninfected level. In vitro amino acid incorporation by mitochondria required adenosine triphosphate (ATP), Mg2+, and KC1 and the energy sources from oxidative phosphorylation as well as from ATP-generating system. This incorporation was inhibited by ribonuclease (RNase), deoxyribonuclease (DNase), actinomycin D, mitomycin C, puromycin, and chloramphenicol added in the reaction medium. The pretreatment of the mitochondria with DNase and actinomycin D reduced the rate of incorporation. The mitochondria incorporated 3H-guanosine triphosphate (GTP) and this activity was blocked by actinomycin D. The presence in this system of 15,000 g supernatant cell sap fraction or bacterial contamination was carefully checked obtaining a negative result. The reaction product into which l4C-amino acids incorporated was solubilized by trypsin. The nature of the amino acid incorporating activity of isolated mitochondria obtained from TMV-infected tobacco leaves is discussed.
  Physiologia Plantarum 04/2006; 19(4):888 - 899. · 3.11 Impact Factor
• Article: A cytochemical study of tobacco leaf cells infected with tobacco mosaic virus

  Tsuyoshi Takahashi, Tokuzo Hirai
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  ABSTRACT: Cytochemical demonstration of the presence of some enzymes and other cell constituents in the epidermal cells of tobacco leaves infected with tobacco mosaic virus was investigated. Changes of some enzyme activities were found in the cells that had crystalline virus inclusions. In inclusion-bearing cells, the activities of adenosine triphosphatase, ribonuclease, nonspecific acid phosphatase, some dehydrogenases, cytochrome oxidase, dopa oxidase, and glucosan phosphorylase decreased, whereas phospholipase activity was activated, as compared with inclusion-free cells from inoculated leaves. No significant differences in activities of nonspecific alkaline phosphatase, 5-nucleotidase, glucose-6-phosphatase, lipase, and aldolase were found between inculsion-bearing and inclusion-free cells. The localization of ribonucleic acid, deoxyribonucleic acid, amino acid components of proteins except sulfhydryl (SH) groups, lipids, and polysaccharides in inclusion-bearing cells was not strikingly different from that in inclusion-free cells. Ferric iron and magnesium, in addition to SH group, were absent in inclusion-bearing cells. The results were interpreted as indicating a decrease of synthetic activities in inclusion-bearing cells.
  Virology 05/1963; · 3.35 Impact Factor