| Abstract: | In many ciliates, young exconjugant clones demonstrate sexual immaturity: they are not able to conjugate with mature cells of complementary mating types (MTs). After several scores of cell divisions, a short period of adolescence (partial maturity) commonly occurs followed by maturation, after which these cells are able to conjugate with cells of other, i.e. complementary, MTs again. Tavrovskaja (1981) reported a significant reduction in the maturity period in Dileptus anser clones, grown from exconjugant ciliates regenerated from small cell fragments. To verify this, in the present study exconjugant D. anser cells were bisected with glass needle after 3 to 4 cell divisions following conjugation. The same procedure was performed with survived and regenerated cells on the 2nd and 3rd days. The clones thus obtained were cultivated, and their ability to mate with each of the three standard clones of MT I, II and III was tested week by week. Indeed, in 22 F1 clones from cross N 7C (MT I) x N 2 (MT II) the immaturity period was reduced 1.4-3.4-fold (2.18 in average) after a threefold bisection, as compared with that in intact subclones. Similarly, in 27 F1 clones from cross N 20 (MT I) x N 14 (MT II) this period was shortened 1.6-3.0-fold (2.19 in average). 12 of these clones showed a 0.9-2.4-fold (1.53 in average) reduction after a single bisection, and 1.6-2.8 (2.12 in average) after a threefold operation. Thus, micrurgical fragmentation of young exconjugant cells can be used to accelerate maturation in D. anser. |
