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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3157

Kosaka Toshikazu; Autogamy and Autogamy Inheritance in Euplotes woodruffi Syngen 1 (Ciliophora). Zoological Science 9:101-111, 1992

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In the Euplotes woodruffi complex which consists of syngen 1, syngen 2, syngen 3 and the autogamy group, autogamy is known in all of the stocks belonging to syngen 2 and the autogamy group but not in syngen 1 and 3. However, a recent study has revealed the one exceptional stock of syngen 1 is endowed with autogamy ability. Stock KB-16 which was collected from brackish water could undergo both autogamy and conjugation. The viability of exautogamous cells was generally over 70%. The length of autogamy immaturity was between 43 and 65 cell divisions in the exautogamous clones. Through autogamy, the stock produced viable F1, F2, and F3 exautogamous clones with autogamy ability. Since non-autogamous clones have never been obtained among them, the parental stock is considered to be homozygous for the autogamy trait. All exautogamous clones derived from the autogamy stock could also conjugate with complementary mating type stocks of syngen 1. When the stock was crossed with a doublet clone from non-autogamous stock, all of the singlet and doublet F1 exconjugants from the cross showed autogamy ability. Thus, autogamy ability is hereditary also through conjugation. Because the results showed that autogamy occurred in heterozygotes and the heterozygotes produced progenies with and without the autogamy trait at a ratio of 3:1 through the next autogamy, the trait is considered to be a dominant allele. To study the features of autogamy in this stock is very important in clarifying the evolution of sexual reproduction in the E. woodruffi complex as well as the evolution of sexual reproduction in ciliates. From the results, a possible evolutionary relationship of the E. woodruffi complex is discussed.