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.

中文翻译：

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多义泥fish道场泥lo中的姐妹染色体配对确保了克隆繁殖。

野生型道场泥ach（Misgurnus anguillicaudatus）通常以生殖腺二倍体（2n = 50）双性繁殖，但在日本某些地区存在雌激素繁殖的克隆二倍体系（2n = 50）。克隆被认为是从物种内两个遗传多样性群体A和B之间过去的杂交事件发展而来的。使用重复序列“ ManDra”作为探针的荧光原位杂交分析清楚地区分了克隆的总共50个二倍体染色体中的B组衍生的25条染色体，提供了其杂交起源的强大分子细胞遗传学证据。在减数分裂中，二倍体野生型显示25个二价，而二倍体克隆显示50个二价，表明存在100条染色体。在性别反转的克隆雄性的减数分裂染色体中，在50个二价物中有25个检测到ManDra信号，而在具有主要核糖体RNA编码区的两个二价中只有一个显示出两个阳性的ManDra信号。在克隆雌性中，在50个二价物中约有25个检测到ManDra信号。因此，应通过减数分裂前的内吞作用，将来自不同组的每个祖先染色体的姐妹染色体之间的配对增加一倍，从而产生未减少的配子。由于没有重组或交叉的影响，姐妹染色体配对应确保产生未还原的等基因克隆配子。未减配配体应通过减数分裂前的内吞作用从不同群体的每个祖先染色体中倍增的姊妹染色体之间配对产生。由于没有重组或交叉的影响，姐妹染色体配对应确保产生未还原的等基因克隆配子。未减配配体应通过减数分裂前的内吞作用从不同群体的每个祖先染色体中倍增的姊妹染色体之间配对产生。由于没有重组或交叉的影响，姐妹染色体配对应确保产生未还原的等基因克隆配子。