Clonal reproduction assured by sister chromosome pairing in dojo loach, a teleost fish
Clonal reproduction assured by sister chromosome pairing in dojo loach, a teleost fish
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DOI：
10.1007/s10577-018-9581-4
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发表时间：
2018-06
影响因子：
2.6
通讯作者：
Masamichi Kuroda;T. Fujimoto;M. Murakami;E. Yamaha;K. Arai
中科院分区：
文献类型：
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作者：
Masamichi Kuroda;T. Fujimoto;M. Murakami;E. Yamaha;K. Arai
野生型泥鳅(Misgurnus Anguillicaudatus)通常以雌雄配子体二倍体(2n = 50)的形式进行两性生殖，但在日本某些地区也存在雌核发育繁殖的克隆二倍体品系(2n = 50)。克隆被认为是从过去的杂交事件(S)在物种内两个遗传不同的群体A和B之间发展而来的。以重复序列“Mandra”为探针的荧光原位杂交分析清楚地从该克隆的50条二倍体染色体中区分出25条来自B群的染色体，为其杂交起源提供了强有力的分子细胞遗传学证据。在减数分裂过程中，二倍体野生型表现出25条二价体，而二倍体克隆表现出50条二价体，表明存在100条染色体。在性反转克隆雄株的减数分裂染色体中，在50个二价体中有25个检测到Mandra信号，而在具有主要核糖体RNA编码区的两个二价体中只有一个显示出两个阳性Mandra信号。在克隆雌性中，在50个二价体中大约有25个检测到曼德拉信号。因此，未减数配子应该是通过减数分裂前的减数分裂产生来自不同群体的每个祖先染色体加倍的姐妹染色体之间的配对。姊妹染色体配对由于不受重组或交换的影响，应确保产生未减少的等基因克隆配子。
Wild-type dojo loach (Misgurnus anguillicaudatus) commonly reproduces bisexually as a gonochoristic diploid (2n = 50), but gynogenetically reproducing clonal diploid lines (2n = 50) exist in certain districts in Japan. Clones have been considered to develop from past hybridization event(s) between two genetically diverse groups, A and B, within the species. Fluorescence in situ hybridization analyses using the repetitive sequence “ManDra” as a probe clearly distinguished 25 chromosomes derived from group B out of a total of 50 diploid chromosomes of the clone, providing strong molecular cytogenetic evidence of its hybrid origin. In meiosis, diploid wild-type showed 25 bivalents, while diploid clones revealed 50 bivalents, indicating the presence of 100 chromosomes. In meiotic chromosome spreads in sex-reversed clonal males, ManDra signals were detected in 25 out of 50 bivalents, and only one out of two bivalents possessing major ribosomal RNA coding regions exhibited two positive ManDra signals. In clonal females, ManDra signals were detected in approximately 25 out of 50 bivalents. Thus, unreduced gametes should be generated by the pairing between sister chromosomes doubled from each ancestral chromosome from the different groups by premeiotic endomitosis. Sister chromosome pairing should assure production of unreduced isogenic clonal gametes due to the absence of the influence of recombination or crossing over.