Time-course analysis of nuclear events during conjugation in the marine ciliate Euplotes vannus and comparison with other ciliates (Protozoa, Ciliophora)
Time-course analysis of nuclear events during conjugation in the marine ciliate Euplotes vannus and comparison with other ciliates (Protozoa, Ciliophora)
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海洋纤毛虫 Euplotes vannus 接合过程中核事件的时程分析以及与其他纤毛动物（原生动物、纤毛纲）的比较
DOI：
10.1080/15384101.2018.1558871
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发表时间：
2019-02-01
期刊：
影响因子：
4.3
通讯作者：
Gao, Feng
中科院分区：
文献类型：
--
作者：
Jiang, Yaohan;Zhang, Tengteng;Gao, Feng
纤毛虫代表着一组形态和遗传上不同的单细胞真核生物，它们将生殖系和体细胞的功能分离成两种类型的核，并在有性交配过程中表现出复杂的细胞遗传学事件，这是在所谓的交配型系统的控制下进行的。研究纤毛虫的接合作用可能有助于我们理解有性和受精的起源和进化。在目前的工作中，我们利用模式物种凡纳游毛虫详细研究了交配的有性过程，并将这些核事件与其他纤毛虫中发生的核事件进行了比较。我们的结果表明：1)接合过程需要约75h才能完成：最长的一步是发育新的大核(约64h)，然后是减数分裂I的核分裂(5h)，有丝分裂通常只需2小时；2)有三个前合子分裂(有丝分裂和减数分裂I和II)，产生的8个核中有2个成为原核；3)原核交换和融合后，发生2个合子后分裂，4个产物中的2个分别分化为新的微核和大核，亲本大核完全退化；4)不同纤毛虫接合过程中的核事件比较表明，一般有3个合子前分裂，而合子后分裂的数目变化很大。这些结果可以为研究该物种的交配型系统和分析参与有性过程的不同步骤的基因提供参考。
ABSTRACT Ciliates represent a morphologically and genetically distinct group of single-celled eukaryotes that segregate germline and somatic functions into two types of nuclei and exhibit complex cytogenetic events during the sexual process of conjugation, which is under the control of the so-called “mating type systems”. Studying conjugation in ciliates may provide insight into our understanding of the origins and evolution of sex and fertilization. In the present work, we studied in detail the sexual process of conjugation using the model species Euplotes vannus, and compared these nuclear events with those occurring in other ciliates. Our results indicate that in E. vannus: 1) conjugation requires about 75 hours to complete: the longest step is the development of the new macronucleus (ca. 64h), followed by the nuclear division of meiosis I (5h); the mitotic divisions usually take only 2h; 2) there are three prezygotic divisions (mitosis and meiosis I and II), and two of the eight resulting nuclei become pronuclei; 3) after the exchange and fusion of the pronuclei, two postzygotic divisions occur; two of the four products differentiate into the new micronucleus and macronucleus, respectively, and the parental macronucleus degenerates completely; 4) comparison of the nuclear events during conjugation in different ciliates reveals that there are generally three prezygotic divisions while the number of postzygotic divisions is highly variable. These results can serve as reference to investigate the mating type system operating in this species and to analyze genes involved in the different steps of the sexual process.