Untersuchungen über Reversions-und Segregationsverhalten eines außerkaryotischen Gens von Chlamydomonas reinhardii zur Bestimmung des Erbträgers
Springer Online Journal Archives 1860-2000
Summary Streptomycin sensitive (ss) revertants were obtained from the streptomycin dependent mutant sd 3 by transfer to streptomycin-free medium. Contrary to ss-wildtype cells these ss-revertants were able to form new sd-colonies on streptomycin-medium. These secondary sd-cells were identical with the original sd 3-mutant. The frequency of formation of the secondary sd-colonies was different, it varied depending on the revertant strain from 0 to the remarkable number of 10−2. With increasing length of cultivation of the ss-revertants the capability of producing sd-cells decreased continuously. Finallym after 8 weeks the zero value was reached. The rate of decrease was depending on the revertant strain. These results show, that most of the newly formed revertants in addition to ss-information copies still possessed sd-copies which were segregating in the process of cell-division and producing secondary sd-colonies on streptomycin-medium. The sd-information is present in numerous copies; proved through the variable frequency of formation, the variable rate of decrease of sd-formation and the undiminished amount of segregation after cloning. Sager and Ramanis have shown that the genes of the single chloroplasts of the Chlamydomonas-cell are present only in two copies. The sd 3-information is located on the more numerous mitochondria if the statement of Sager and Ramanis proves to be true for the vegetative cells in principle.
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