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Disturbance of the Determination of Germinal and Somatic Nuclei by Heat Shock in Paramecium caudatum
Author(s) -
YANG XIANYU,
TAKAHASHI MIHOKO
Publication year - 1999
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.1999.tb04583.x
Subject(s) - macronucleus , paramecium caudatum , biology , paramecium , microbiology and biotechnology , telophase , somatic cell , nucleus , cytoplasm , genetics , meiosis , prophase , ciliate , gene
During conjugation of Paramecium caudatum , nuclear determination occurs soon after the third postzygotic division: one of the four anterior nuclei becomes the micronucleus and the remaining three degenerate, while four posterior nuclei differentiate into macronuclear anlagen. Macronuclear differentiation is supposed to be dependent on a cytoplasmic differentiation factor. In this study, postzygotic cells were subjected to heat shock for 30 min and nuclear changes were observed by staining with carbol fuchsin solution. When heat shock was initiated during the period from metaphase to telophase of the third postzygotic division, cells showed an excess of macronuclear anlagen and were typically amicronucleate. Abnormal nuclear localization around the end of the third (last) postzygotic division may explain the origin of these kinds of cells. A similar phenomenon appeared after treatment with actinomycin D or emetine. Since heat shock did not inhibit macronuclear differentiation but destroyed the formation of micronuclei, some factor(s) probably plays an essential role in nuclear determination, especially in the protection of the micronuclei.