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Profiles of conjugation induction by potassium ions in four different Ca
Mihoko Takahashi1, Shin-Ichi Shirakura1
1Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305, Japan.
Abstract:
Conjugation of Paramecium caudatum among cells of a single mating type can be induced parthenogenetically by exposing them to certain chemical solutions, a process called chemical induction of conjugation. The ionic conditions for chemical induction of conjugation are also the conditions that are required for the induction of the activation of voltage dependent Ca2+ channels in Paramecium. Four mutants controlled by independent gene loci with defects in Ca2+ channels, were subjected to an induction solution containing various concentrations of KCl and 0.01, 0.06 and 0.6 mmol/L CaCl2 . Conjugation was able to be induced chemically in all four mutants. However, some locus-dependent differences were observed in the profiles of induction. Mutants controlled by different alleles but with the same locus were similar in their profile of induction, even when they exhibited opposite phenotypes on the activation of Ca2+ channels. These results suggest that the function of Ca2+ channels is not directly involved in the mechanism of chemical induction of conjugation. The locus dependency observed reflects the different role of each gene controlling Ca2+ channel functions.
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