Triploid planarian reproduces truly bisexually with euploid gametes produced through a different meiotic system between sex
Triploid planarian reproduces truly bisexually with euploid gametes produced through a different meiotic system between sex
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三倍体涡虫通过不同性别的减数分裂系统产生的整倍体配子进行真正的双性繁殖
DOI：
10.1007/s00412-013-0449-2
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发表时间：
2014
期刊：
影响因子：
1.6
通讯作者：
Midori Matsumoto
中科院分区：
文献类型：
--
作者：
Ayako Chinone;Hanae Nodono;Midori Matsumoto
虽然多倍体在植物和一些动物中很常见，但多倍体化往往会导致繁殖失败。特别是三倍体，其特征在于减数分裂过程中染色体配对和分离的问题，这可能导致非整倍体配子并导致不育。因此，它们通常被认为只进行无性繁殖。在扁形动物琉球三角线虫的情况下，具有三倍体核型的种群通常在自然界中被发现为裂殖和卵生的三倍体。如果用有性的真涡虫喂养裂殖三倍体，它们也可以通过实验性化，从而发育出性腺和其他生殖器官。完全有性化的蠕虫开始通过交配而不是分裂繁殖。在这项研究中，我们检查了通过有性化三倍体繁殖获得的后代的基因型，发现后代遗传了双亲的基因，即，它们真的是两性繁殖。此外，减数分裂染色体行为在三倍体性化的涡虫显着不同的男性和女性生殖系，在女性生殖系细胞保持三倍体，直到前期I，而男性生殖系细胞似乎成为二倍体进入减数分裂之前。双线期晚期的卵母细胞不仅含有配对的二价体，而且含有未配对的单价体，如果它们在随后的过程中保留下来，则可能产生二倍体卵。因此，三倍体真涡虫可以通过雌性和雄性生殖系中不同的减数分裂系统形成整倍体配子，从而能够进行有性繁殖，这与许多其他三倍体生物不同。
Although polyploids are common among plants and some animals, polyploidization often causes reproductive failure. Triploids, in particular, are characterized by the problems of chromosomal pairing and segregation during meiosis, which may cause aneuploid gametes and results in sterility. Thus, they are generally considered to reproduce only asexually. In the case of the PlatyhelminthesDugesia ryukyuensis, populations with triploid karyotypes are normally found in nature as both fissiparous and oviparous triploids. Fissiparous triploids can also be experimentally sexualized if they are fed sexual planarians, developing both gonads and other reproductive organs. Fully sexualized worms begin reproducing by copulation rather than fission. In this study, we examined the genotypes of the offspring obtained by breeding sexualized triploids and found that the offspring inherited genes from both parents, i.e., they reproduced truly bisexually. Furthermore, meiotic chromosome behavior in triploid sexualized planarians differed significantly between male and female germ lines, in that female germ line cells remained triploid until prophase I, whereas male germ line cells appeared to become diploid before entry into meiosis. Oocytes at the late diplotene stage contained not only paired bivalents but also unpaired univalents that were suggested to produce diploid eggs if they remained in subsequent processes. Triploid planarians may therefore form euploid gametes by different meiotic systems in female and male germ lines and thus are be able to reproduce sexually in contrast to many other triploid organisms.