Lipid metabolism is a key biological process involving the synthesis and degradation of lipids in organisms. In the liver, triglyceride (TG) synthesis mediates the storage of fats for energy, which is catalysed by diacylglycerol acyltransferase-2 (DGAT2). Herein, we compared TG-related indexes in serum from Nile tilapia (Oreochromis niloticus), blue tilapia (O. aureus) and hybrid offspring (Nile tilapia ♀ × blue tilapia ♂). The results showed that serum TG levels were significantly higher in the hybrid tilapia (6.95 ± 1.48 mmol/L) than that in blue tilapia (4.39 ± 1.02 mmol/L). Tissue distribution analysis suggested that DGAT2 was mainly expressed in the liver and muscle. Furthermore, hybrid tilapia exhibited higher mRNA expression of DGAT2 in the liver than the parents. Additionally, the allelic gene expression assay indicated that the alleles of DGAT2 gene from the two parental species were expressed at equal levels. To elucidate the epigenetic regulation of DGAT2 gene expression, the DNA methylation levels at the putative promoter region of DGAT2 in hybrid tilapia and its parents were compared. We found lower DNA methylation levels at the putative promoter region of DGAT2 in hybrid tilapia as compared to the paternal species in liver. DNA methylation levels in the putative promoter region were negatively correlated with DGTA2 expression in tilapia. Three CpG sites were significantly correlated with DGAT2 expression in tilapia. Overall, the present evidence suggests that DNA methylation is associated with the elevated expression of DGAT2 in hybrid tilapia. These results provide new evidence for epigenetic regulation of genes in hybrids, which may aid to understanding of heterosis for fish hybridization breeding and superiorities of nutrient utilization in hybrids.

中文翻译：

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DNA甲基化模式与杂交罗非鱼中DGAT2表达升高有关

脂质代谢是一个关键的生物过程，涉及生物体内脂质的合成和降解。在肝脏中，甘油三酯 (TG) 合成介导脂肪储存能量，这是由二酰基甘油酰基转移酶-2 (DGAT2) 催化的。在这里，我们比较了血清TG-相关指标从尼罗罗非鱼（尼罗罗非鱼），奥利亚罗非鱼（Ò。 金黄色葡萄球菌）和杂交后代（尼罗罗非鱼♀×蓝罗非鱼♂）。结果表明，杂交罗非鱼的血清TG水平（6.95±1.48 mmol/L）显着高于蓝罗非鱼（4.39±1.02 mmol/L）。组织分布分析表明DGAT2主要在肝脏和肌肉中表达。此外，杂交罗非鱼在肝脏中表现出比亲本更高的 DGAT2 mRNA 表达。此外，等位基因表达分析表明，来自两个亲本物种的 DGAT2 基因的等位基因表达水平相同。为了阐明 DGAT2 基因表达的表观遗传调控，比较了杂交罗非鱼及其亲本 DGAT2 假定启动子区域的 DNA 甲基化水平。我们发现与肝脏中的父本物种相比，杂种罗非鱼中 DGAT2 的推定启动子区域的 DNA 甲基化水平较低。假定启动子区域中的 DNA 甲基化水平与罗非鱼中的 DGTA2 表达呈负相关。三个 CpG 位点与罗非鱼中的 DGAT2 表达显着相关。总体而言，目前的证据表明 DNA 甲基化与杂交罗非鱼中 DGAT2 的表达升高有关。这些结果为杂种基因的表观遗传调控提供了新的证据，有助于了解鱼类杂交育种的杂种优势和杂种营养利用的优势。三个 CpG 位点与罗非鱼中的 DGAT2 表达显着相关。总体而言，目前的证据表明 DNA 甲基化与杂交罗非鱼中 DGAT2 的表达升高有关。这些结果为杂种基因的表观遗传调控提供了新的证据，有助于了解鱼类杂交育种的杂种优势和杂种营养利用的优势。三个 CpG 位点与罗非鱼中的 DGAT2 表达显着相关。总体而言，目前的证据表明 DNA 甲基化与杂交罗非鱼中 DGAT2 的表达升高有关。这些结果为杂种基因的表观遗传调控提供了新的证据，有助于了解鱼类杂交育种的杂种优势和杂种营养利用的优势。