Diploid clone produces unreduced diploid gametes but tetraploid clone generates reduced diploid gametes in the Misgurnus loach
Diploid clone produces unreduced diploid gametes but tetraploid clone generates reduced diploid gametes in the Misgurnus loach
复制标题
在泥鳅中，二倍体克隆产生未减少的二倍体配子，但四倍体克隆产生减少的二倍体配子
DOI：
10.1095/biolreprod.111.093302
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发表时间：
2012
影响因子：
3.6
通讯作者：
Katsutoshi Arai
中科院分区：
文献类型：
--
作者：
Kagayaki Morishima;Hiroyuki Yoshikawa;Katsutoshi Arai
大多数泥鳅个体都是双性繁殖的，但隐秘的克隆谱系是通过未减数二倍体卵的自然雌核发生来繁殖的，这些卵在遗传上与母体体细胞相同。三倍体后代通常是由于精子核意外掺入二倍体卵子而产生的。在该物种中，通过雄激素治疗和环境影响很容易诱导从遗传雌性到生理雄性的性别逆转。在这里，我们通过两种方法产生了克隆四倍体个体：1）克隆二倍体雌性的二倍体卵与激素性别逆转的克隆二倍体雄性的二倍体精子受精；2）在雌核发育开始后人工抑制克隆二倍体雌性卵中第二极体的释放。除了染色体组或基因组的数量之外，克隆二倍体和四倍体个体之间没有遗传差异。克隆四倍体雄性永远不会产生未还原的四倍体精子，只会产生与克隆二倍体遗传相同的二倍体精子。同样，克隆四倍体雌性不会形成未还原的四倍体卵，只形成二倍体卵。然而，这些卵的基因型与原始克隆的基因型相同，并且几乎所有卵都启动了自然雌核发育。因此，克隆四倍体泥鳅的配子发生是由配对的两个染色体组的存在控制的，从而保持正常的减数分裂过程，即二价体的形成和随后的两次连续分裂。
Most individuals of the loachMisgurnus anguillicaudatusreproduce bisexually, but cryptic clonal lineages reproduce by natural gynogenesis of unreduced diploid eggs that are genetically identical to maternal somatic cells. Triploid progeny often occur by the accidental incorporation of a sperm nucleus into diploid eggs. Sex reversal from a genetic female to a physiological male is easily induced in this species by androgen treatment and through environmental influences. Here, we produced clonal tetraploid individuals by two methods: 1) fertilization of diploid eggs from a clonal diploid female with diploid sperm of a hormonally sex-reversed clonal diploid male and 2) artificial inhibition of the release of the second polar body in eggs of clonal diploid females just after initiation of gynogenetic development. There is no genetic difference between the clonal diploid and tetraploid individuals except for the number of chromosome sets or genomes. Clonal tetraploid males never produced unreduced tetraploid sperm, only diploid sperm that were genetically identical to those of a clonal diploid. Likewise, clonal tetraploid females did not form unreduced tetraploid eggs, just diploid eggs. However, the eggs' genotypes were identical to those of the original clone, and almost all the eggs initiated natural gynogenesis. Thus, gametogenesis of the clonal tetraploid loach is controlled by the presence of two chromosome sets to pair, thereby preserving the normal meiotic process, i.e., the formation of bivalents and subsequently two successive divisions.