莫荷罗非鱼“广福1号”与其亲本间DNA甲基化的差异分析

Analysis of DNA methylation difference between “Mohe” hybrid tilapia and its parents

为了探讨罗非鱼杂种优势形成过程中基因组DNA甲基化模式的变化,运用甲基化敏感扩增多态技术(methylation sensitive amplified polymorphism,MSAP)分析橙色莫桑比克罗非鱼、荷那龙罗非鱼及其杂交种莫荷罗非鱼"广福1号"的皮肤、肌肉和鳃等11种组织的DNA甲基化水平差异。采用16对引物进行选择性扩增,经聚丙烯酰胺凝胶电泳带型分析结果显示:莫荷罗非鱼"广福1号"及其亲本在不同组织间的甲基化水平存在组织特异性,相同组织不同亲、子代罗非鱼间的甲基化程度亦不同;橙色莫桑比克罗非鱼、荷那龙罗非鱼以及"广福1号"各组织平均总甲基化水平分别为32.21%、38.03%和29.77%,莫荷罗非鱼"广福1号"的甲基化水平低于双亲;与亲本相比,莫荷罗非鱼"广福1号"的甲基化模式除了大多数保持稳定遗传(A、B、C类型分别为19.67%、29.99%、25.42%)之外,24.92%胞嘧啶位点发生去甲基化和超甲基化,且去甲基化位点(E类型,15.73%)多于超甲基化位点(D类型,9.19%)。研究表明,莫荷罗非鱼"广福1号"基因组DNA的低甲基化特征和甲基化模式的重调可能与耐盐杂种优势有关。

DNA methylation difference of eleven tissues of Oreochromis mossambicus, Oreochromis hornorum and ＂ Mohe＂ hybrid tilapia（O. mossambicus♀×O. hornorum♂）, such as skin, muscle and gill etc. was analyzed to explore the change of methylation pattern during the interspecific hybridization using methylation sensitive amplified polymorphism（MSAP）. 16 pairs of primers were used to amplify selectively. The results of electrophoretic banding analysis showed that there were differences in the methylation levels among these different tissues of the same species and between the same tissues among ＂ Mohe＂ hybrid tilapia and its parents; the average methylation level of these tissues from O. mossambicus, O. hornorum and ＂ Mohe＂ hybrid progenies was 32.21%,38.03% and 29.77%, respectively. The methylation level of hybrid progenies was lower than those of the parental progenies. Most of the methylation patterns of the hybrid progenies were similar to the parental progenies（A, B and C types, 19.67%, 29.99% and 25.42%）, while 24.92% cytosine demethylation and hypermethylation were found in the genome of hybrid progenies and the number of demethylation sites（E type, 15.73%） was greater than that of hypermethylation sites（D type, 9.19%）. These results suggested that the genomic DNA hypomethylation and the reshuffling of the DNA methylation pattern in the hybrid progenies might be associated with the heterosis.The present findings established epigenetic foundation to further reveal the heterosis mechanism of tilapia.