Ref ID : 7597
Stephen F. NG; Transplantation of the Germ Nucleus in Paramecium tetraurelia and its Genetic Consequences. Protistologica XVII(4):489-496, 1981
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The micronucleus (nd/nd trichocyst nondischarge) of Paramecium tetraurelia was transplanted by micropipetting into amicronucleate cells (nd+/nd+) obtained by laser microbeam irradiation. 11 unimicronucleate cell lines were established. In all except one the transplanted micronucleus replicated every cell fission. Genetic tests were performed on these cell lines to assess whether they could function normally during sexual reproduction. Autogamy in 9 of them was normal, in 2 was abortive. These suggested that the micronuclei transplanted into the latter were damaged. The 9 normal cell lines were crossed to normal bimicronucleates. Gene marker exchange between the two conjugants with subsequent segregation in F2 postautogamous clones was demonstrated, thus showing the formation of normal stationary and migratory gametic nuclei. The functional competence of the transplanted micronucleus in early autogamy in comparison with the normal inherent micronucleus was also studied by transplanting one micronucleus (nd/nd) into unimicronucleate cells (nd+/nd+). The transplanted cell lines were then induced to undergo autogamy and the postautogamous clones were tested for trichocyst discharge. The result showed that in 7 out of 10 cases the transplanted and inherent micronuclei were functionally equivalent; in 2 cases the transplanted one was less, but in 1 case more, competent than the inherent one.