| Budget Amount *help |
¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1991: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1990: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
Distribution of pyrenoids which contain the chloroplast-nucle- oid DNA was surveyed in fresh-water green algae. It was newly found in three genera and four species(Trebouxia sp. T. potteri, Parietochloris pseudoalveolaris, Stichococcus bacillaris) and two other unidentified green flagellates. In addition,other new-type of chloroplast nucleoids was discovered in two genera and three species(Tetraspora gelatinosa,T.lubricus,Diplosphaera chodatii), in which the nucleoid DNA lacalizes outside around the sheath of pyrenoid starch. The behavior of chloroplast nucleoids was investigated throughout the whole life cycle of P.pseudoalveolaris in which only asexual reproduction takes place. During of differentiation of reproductive cells (zoospores or aplanospores) the chloroplast repeated to divide and pyrenoids disappeared concomitantly, nucleoid DNA scattered as many small granles through chloroplasts. As the reproductive cells differentiated into the vegetative cells pyrenoids were reformed and nucleoid DNA also began to localize into the pyrenoid matrix.
The isolation method of chloroplasts and their pyrenoids was established, using the coenocytic green alga,Caulerpa, the chloroplasts of which have pyrenoids that contain chloroplast nucleoid DNA and Rubisco. It was revelaed that pyrenoid matrix is composed of six proteins, 97KDa, 63KDa, 54KDa 28KDa, 14KDa and DNA. In the supernatant which was gained from NaCl-treatment of pyrenoid fraction 54KDa, 14KDa and 44KDa proteins were present. The former two proteins correspond to the large and small subunits of Rubisco, respectively.
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