云纹石斑鱼、鞍带石斑鱼及其杂交F1的DNA甲基化分析

DNA Methylation Analysis of Epinephelus moara, Epinephelus lanceolatus and Their F1 Hybrid

中文关键词: 云纹石斑鱼  鞍带石斑鱼  杂交F1  DNA甲基化

英文关键词: Epinephelus moara  Epinephelus lanceolatus  Hybrid F1  DNA methylation

中文摘要:

      为探讨石斑鱼杂种优势形成过程中基因组DNA甲基化水平的变化，本研究采用甲基化敏感扩增多态性(Methylation-sensitive amplification polymorphism, MSAP)技术检测云纹石斑鱼(Epinephelus moara)、鞍带石斑鱼(Epinephelus lanceolatus)及云纹石斑鱼(♀)×鞍带石斑鱼(♂)杂交F1 3个群体的基因组DNA甲基化水平，分析杂交F1与亲本基因组DNA甲基化水平的差异。结果显示，云纹石斑鱼和鞍带石斑鱼的基因组DNA属于甲基化程度较高的类群；云纹石斑鱼、鞍带石斑鱼及其杂交F1的DNA总甲基化率分别为60.62%、59.38%和55.78%，DNA全甲基化率分别为31.37%、30.67%和29.27%，DNA半甲基化率分别为29.25%、28.71%和26.51%；杂交F1的DNA总甲基化率、全甲基化率和半甲基化率均低于双亲，并存在极显著差异(P<0.01)，3个群体的全甲基化率均大于半甲基化率。研究表明，云纹石斑鱼(♀)×鞍带石斑鱼(♂)杂交F1 DNA甲基化水平与杂种优势呈负相关，杂交F1 DNA甲基化水平的降低可能是形成快速生长等杂种优势的原因之一。

英文摘要:

      DNA methylation is one of the most important epigenetic modifications. It is vital to maintain the stability of the whole genome and regulate the expression of tissue-specific genes. Methylation level and distribution throughout genomic DNA are significantly correlated with gene expression rate. In order to investigate the changes of genomic DNA methylation level associated with heterosis of Epinephelus spp., we applied methylation-sensitive amplification polymorphism (MSAP) technology to detect the genomic DNA methylation levels of longtooth grouper (E. moara), giant grouper (E. lanceolatus), and their F1 hybrid [E. moara (♀) × E. lanceolatus (♂)], and we analyzed the difference of DNA methylation level between the F1 hybrid and parents. The results showed that overall genomic DNA methylation was higher in E. moara and E. lanceolatus. The total methylation rates of E. moara, E. lanceolatus, and the F1 hybrid were 60.62%, 59.38%, and 55.78%, respectively. The rates of fully methylated sites were 31.37%, 30.67%, and 29.27%, respectively, and the hemi-methylation rates were 29.25%, 28.71%, and 26.51%, respectively. The total methylation rate, the full methylation rate, and the hemi-methylation rate of DNA of the F1 hybrid were all significantly lower (P<0.01) than that of either parent. The full methylation rates were all higher than the hemi-methylation rates of E. moara, E. lanceolatus, and the F1 hybrid. The study also showed that the DNA methylation level of the F1 hybrid is negatively correlated with heterosis. Moreover, reduced DNA methylation level of the F1 hybrid may be one of the reasons for the heterosis phenomena such as rapid growth. In general, DNA methylation is negatively correlated with gene expression. The DNA methylation level of the hybrid was lower than either parent, allowing otherwise silenced genes to be activated, enhancing gene expression activity, and resulting in the hybrid progeny exhibiting heterosis. The relationship between methylation level of specific genes and heterosis, the genetic pattern of these DNA methylation sites, the effect on gene structure and function, and the regulatory mechanism require further study.