日本鰻脂肪含量與基因表現量

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  臺灣水產學會刊 (2011) 38:109-124

成長期中的日本鰻 (Anguilla japonica) 其肌肉組織脂肪含量與核內受體 (PPARs, RXRa)及轉錄共同活化子(EDF-1)表現量相關性之研究

珈馬型過氧化物增殖因子活性受體 (PPARg) 對於脂肪生成非常重要，視網酸x受體 (RXRs) 是協助過氧化物增殖因子活性受體執行能量調節功能的必須夥伴分子，而一型血管內皮分化相關因子 (EDF-1) 是珈馬型過氧化物增殖因子活性受體控制脂肪代謝的輔因子。成長中的日本鰻其肌肉組織可累積超過20%的脂肪，而其脂肪細胞位於肌肉組織間，所以這些因子和鰻魚脂肪生成的關係值得研究，因為脂肪是鰻魚肉質與風味的重要因素。鰻魚從鰻線開始用市售飼料養殖，並定時採樣，我們選殖PPARs、RXRa與 EDF-1等基因片段，以反轉錄-PCR分析肌肉組織基因表現量與肌肉組織中粗脂肪含量。結果顯示：脂肪含量和PPARg、RXRa和EDF-1之基因表現量正相關，但脂肪含量與脂肪酸延長脢或其他PPAR表現量無顯著相關性；而只有PPARg與RXRa的基因表現量呈顯著正相關；脂肪酸延長脢基因表現量只和PPARg 與 RXRa 基因表現量顯著相關，但此相關不見於脂肪酸延長脢與EDF-1之間。我們從日本鰻得到的結果結果暗示PPARg、RXRa 與EDF-1在脂肪生成功能的保守性，操控這些因子可能可以利用於水產養殖上。

關鍵詞: 日本鰻、一型血管內皮分化相關因子、成長、脂肪、脂肪生成、氧化物增殖因子活性受體、視網酸x受體

Correlation between lipid content and nuclear receptors (PPARs, RXRa) as well as a transcriptional coactivator (EDF-1) gene expression levels in muscle tissues of Anguilla japonica during growth

PPARg is essential for the lipogenesis; RXRs obligate heterodimer partner with PPARs to help coordinate energy balance; EDF-1 is a cofactor for PPARg regulating lipid metabolism. Eels (Anguilla spp.), a primitive vertebrate, accumulate lipids exceed 20% in its muscle tissues where adiopocytes are found. So it will be interesting to elucidate these factors on lipid synthesis in the growing Japanese eels (Anguilla japonica). PPARs, RXRa, and EDF-1 have been partially cloned, expression levels of these genes in muscle tissues were tested by RT-PCR, muscle tissues lipid content was followed. Our results indicated that there was a significant correlation between lipid content and PPARg, two forms of RXRa, or EDF-1 while it was not found between lipid content and that of fatty acid elongase, or the other PPARs. Furthermore, a positive correlation was also showed between RXRa and PPARg only. Expression levels of fatty acid elongase were correlated with PPARg and RXRa but not with EDF-1. Our data implied a conserved role of PPARg, RXRa, and EDF-1 on the lipid synthesis from the Japanese eel, to manipulate these factors could be useful on eel aquaculture.

Key words: Anguilla japonica, EDF-1, growth, lipids, lipogenesis, PPAR, RXR