Zhou Yi, Zhu La, Sun Yu, Zhang Hui, Wang Jiaojiao, Qin Weilin, He Wangchao, Zhou Luojing, Li Qi, Zhao Rurong, Luo Kaikun, Tang Chenchen, Zhang Chun, Liu Shaojun
State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Engineering Research Center of Polyploid Fish Reproduction and Breeding of the State Education Ministry, Hunan Normal University, Changsha, China.
Front Genet. 2021 Sep 9;12:717871. doi: 10.3389/fgene.2021.717871. eCollection 2021.
Polyploidy occurs naturally in fish; however, the appearance of these species is an occasional and gradual process, which makes it difficult to trace the changes in phenotypes, genotypes, and regulation of gene expression. The allotetraploid hybrids (4nAT) of red crucian carp (RCC; ♀) × common carp (CC; ♂) generated from interspecies crossing are a good model to investigate the initial changes after allopolyploidization. In the present study, we focused on the changes in the active sites of the testicular transcriptome of the allotetraploid by localization of RNA Pol II CTD YSPTSPS (phospho S5) using immunofluorescence and RNA-seq data bioinformatic analysis. The results showed that there was no significant difference in signal counts of the RNA Pol II CTD (S5) between the different types of fish at the same stages, including RCC, CC, 2nF, and 4nAT, which means that the number of transcriptionally active sites on germ cell chromosomes was not affected by the increase in chromosome number. Similarly, RNA-seq analysis indicated that in the levels of chromosomes and 10-kb regions in the genome, there were no significant changes in the highly active sites in RCC, 2nF, and 4nAT. These findings suggest that at the beginning of tetraploid origin, the active transcriptome site of 4nAT in the testis was conserved in the regions of the genome compared to that in RCC and 2nF. In conclusion, 4nAT shared a similar gene expression model in the regions of the genome with RCC and 2nF with significantly different expression levels.
多倍体在鱼类中自然发生；然而，这些物种的出现是一个偶然且渐进的过程，这使得追踪表型、基因型和基因表达调控的变化变得困难。通过种间杂交产生的红鲫（♀）×鲤鱼（♂）异源四倍体杂种（4nAT）是研究异源多倍体化后初始变化的良好模型。在本研究中，我们通过免疫荧光定位RNA聚合酶II CTD YSPTSPS（磷酸化S5）和RNA-seq数据生物信息学分析，聚焦于异源四倍体睾丸转录组活性位点的变化。结果表明，在相同阶段，包括红鲫、鲤鱼、二倍体杂种（2nF）和4nAT在内的不同类型鱼类之间，RNA聚合酶II CTD（S5）的信号计数没有显著差异，这意味着生殖细胞染色体上转录活性位点的数量不受染色体数增加的影响。同样，RNA-seq分析表明，在基因组的染色体和10 kb区域水平上，红鲫、2nF和4nAT中的高活性位点没有显著变化。这些发现表明，在四倍体起源之初，与红鲫和2nF相比，4nAT睾丸中的活性转录组位点在基因组区域是保守的。总之，4nAT在基因组区域与红鲫和2nF共享相似的基因表达模式，但表达水平存在显著差异。
