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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3857

Donald B. Williams; Clonal Aging in Two Species of Spathidium (Ciliophora: Gymnostomatida). J.Protozool. 27(2):212-215, 1980

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Thirty newly excysted Spathidium spathula (Muller) and 60 newly excysted Spathidium muscicola (Kahl) were selected as progenitors of clonal daily reisolation lines that omitted both conjugation and encystment. Daily division rates were determined for each clone either until it died or until the end of the 170 days of reisolation. Both species had reduced fission rates as they accumulated fissions in the absence of macronuclear reorganization. Spathidium spathula had a significant reduction of daily fission rate after 100-120 fissions and S. muscicola after 20-30 fissions. Older clones of both species contained a noticeable proportion of abnormal organisms. A significant increase (10.5%) in daily fission rate occurred in aged sublines of S. spathula following conjugation (selfing) and its concomitant nuclear reorganization. Spathidium muscicola did not conjugate, but recently excysted sublines, compared to aged lines, had an increased daily fission rate.