摘要
Meiotic bouquet formation(known as crescent formation in Tetrahymena thermophila) is indispensable for homologous pairing and recombination, but the regulatory mechanism of bouquet formation remains largely unknown. As a conjugation specific cyclin gene, CYC2 knockout mutants failed to form an elongated crescent structure and aborted meiosis progress in T. thermophila. γ-H2 A.X staining revealed fewer micronuclear DNA double-strand breaks(DSBs) in cyc2Δ cells than in wild-type cells. Furthermore, cyc2Δ cells still failed to form a crescent structure even though DSBs were induced by exogenous agents,indicating that a lack of DSBs was not completely responsible for failure to enter the crescent stage. Tubulin staining showed that impaired perinuclear microtubule structure may contribute to the blockage in micronuclear elongation. At the same time,expression of microtubule-associated kinesin genes, KIN11 and KIN141, was significantly downregulated in cyc2Δ cells.Moreover, micronuclear specific accumulation of heterochromatin marker trimethylated H3 K23 abnormally increased in the cyc2Δ mutants. Together, these results show that cyclin Cyc2 p is required for micronuclear bouquet formation via controlling microtubule-directed nuclear elongation in Tetrahymena.
Meiotic bouquet formation(known as crescent formation in Tetrahymena thermophila) is indispensable for homologous pairing and recombination, but the regulatory mechanism of bouquet formation remains largely unknown. As a conjugation specific cyclin gene, CYC2 knockout mutants failed to form an elongated crescent structure and aborted meiosis progress in T. thermophila. γ-H2 A.X staining revealed fewer micronuclear DNA double-strand breaks(DSBs) in cyc2Δ cells than in wild-type cells. Furthermore, cyc2Δ cells still failed to form a crescent structure even though DSBs were induced by exogenous agents,indicating that a lack of DSBs was not completely responsible for failure to enter the crescent stage. Tubulin staining showed that impaired perinuclear microtubule structure may contribute to the blockage in micronuclear elongation. At the same time,expression of microtubule-associated kinesin genes, KIN11 and KIN141, was significantly downregulated in cyc2Δ cells.Moreover, micronuclear specific accumulation of heterochromatin marker trimethylated H3 K23 abnormally increased in the cyc2Δ mutants. Together, these results show that cyclin Cyc2 p is required for micronuclear bouquet formation via controlling microtubule-directed nuclear elongation in Tetrahymena.
基金
supported by the National Natural Science Foundation of China(31471999,31572253)
Shanxi Scholarship Council of China(200902)
Aoshan Science and Technology Innovation Program of the Qingdao National Laboratory for Marine Science and Technology
the China Postdoctoral Science Foundation(2014M551961)
the Natural Science Foundation of Shanxi Province(2015011078)
