Triploid is usually considered to be unable to perform normal meiosis due to the abnormal behavior of the three sets of chromosomes. But autotriploid Carassius auratus in the Dongting water system (3n = 150, abbreviated as 3nCC) can perform normal meiosis. In artificial autotriploid Carassius auratus (3n = 150, abbreviated as 3nRR), female individuals undergo normal meiosis and produce mature gametes, while male individuals cannot. To better understand the effects of triploidization on meiosis in fish, we study the structure, methylation level, and expression level of meiosis-related genes (Dmc1, Ph1) in diploid Carassius auratus (2n = 100, abbreviated as 2nCC), Carassius auratus red var.(2n = 100, abbreviated as RCC), 3nCC and 3nRR. The results show that, compared with their diploid ancestors (2nCC and RCC), Dmc1 and Ph1 genes are hypomethylated in all 3nCC and female 3nRR, while are hypermethylated in male 3nRR. Correspondingly, Dmc1 and Ph1 genes are highly expressed in all 3nCC and female 3nRR, while are lowly expressed in male 3nRR. These results indicate that high expression of meiosis-related genes can contribute to restoration of bivalent pairing during meiosis in autotriploid Carassius auratus. This study provides new insights into the effect of DNA methylation on the fertility in triploid fish.

中文翻译：

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三倍体Car鱼减数分裂相关基因（Dmc1，Ph1）表达的分析。

由于三组染色体的异常行为，通常认为三倍体不能进行正常的减数分裂。但是洞庭水系统中的三倍体Car鱼（3n = 150，缩写为3nCC）可以进行正常的减数分裂。在人工三倍体Car鱼（Carassius auratus，3n = 150，缩写为3nRR）中，雌性个体经历正常的减数分裂并产生成熟的配子，而雄性个体则不能。为了更好地理解三倍体对鱼减数分裂的影响，我们研究了结构，甲基化水平和表达水平的减数分裂相关基因（DMC1，PH1二倍体）鲫鱼（2N = 100，简称2nCC），鲫鱼红色版本（2n = 100，缩写为RCC），3nCC和3nRR。结果表明，与它们的二倍体祖先（2nCC和RCC）相比，Dmc1和Ph1基因在所有3nCC和雌性3nRR中均被低甲基化，而在雄性3nRR中则被高甲基化。相应地，Dmc1和Ph1基因在所有3nCC和雌性3nRR中均高表达，而在雄性3nRR中则低表达。这些结果表明减数分裂相关基因的高表达可有助于在三倍体Car鱼减数分裂过程中恢复二价配对。这项研究提供了有关DNA甲基化对三倍体鱼类繁殖力影响的新见解。