Abortive conjugation induced by UV-B irradiation at meiotic prophase in Tetrahymena thermophila.
Conjugating Tetrahymena were irradiated by ultraviolet-B (UV-B) at various stages of conjugation. When the conjugants were exposed to the UV-B at late meiotic prophase (the stage from pachytene to diplotene), abortive conjugation was induced a high frequencies. After completing meiosis, a significant number of the conjugants showed marked anomalies, i.e., failure of nuclear selection after meiosis, and abortion of the subsequent conjugation process such as a postmeiotic division to form gametic nuclei, nuclear exchange, synkaryon formation, and postzygotic development. The conjugating pairs retained the parental macronucleus and separated earlier as compared with a control. The resultant exconjugants degenerated meiotic products and became amicronucleates. These observations strongly suggest the presence of a UV-sensitive molecule that is expressed specifically at the meiotic prophase and that directs the subsequent development after meiosis.
Department of Biology, Faculty of Science, Kanazawa University, Japan.
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D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D008540:Meiosis / Q000528:radiation effects*; D011418:Prophase / Q000528:radiation effects*; D012098:Reproduction / Q000528:radiation effects; D016808:Tetrahymena thermophila / Q000235:genetics / Q000528:radiation effects*; D013997:Time Factors; D014466:Ultraviolet Rays