海水轉移對耐鹽性不同吳郭魚鰓上基因表現之影響

Abstract

莫三比克吳郭魚(Oreochromis mossambicus)存在著耐鹽性不同的品系，造成耐鹽性不同的原因至今仍不清楚，而篩選耐鹽品系吳郭魚對水產養殖上非常重要。經由大量育種選殖出急速轉移到27 ppt 海水中24 小時死亡率低於30 %的耐鹽品系吳郭魚。利用生物晶片比較野生種和耐鹽品系吳郭魚鰓上基因在轉移淡海水的差異，發現大部分被刺激表現的基因的功能為能量代謝和轉錄與轉譯。即時定量聚合酶反應的結果顯示轉移海水後atp1a1 和 slc12a2 在耐鹽品系在3 小時比起野生種有較高的表現量，而slc12a3 在耐鹽品系中明顯下降比野生種迅速。在能量方面基因，耐鹽品系糖解作用相關酵素enolase 1 (eno1)在轉移海水後3 小時有大量表現，而丙酮酸和乳酸在鰓的含量在耐鹽品系皆高於野生種吳郭魚。綜上所述，耐鹽品系較能適應急速鹽度轉移的原因，可能是能更快進行能量代謝及調節運輸蛋白的表現。

Several strains of tilapia (Oreochromis mossambicus) with different salinity tolerances have been found in the field, and the mechanisms of salinity-resistant (SR) are still unknown. Isolation of SR tilapia is very important for aquaculture. In the present study, we identified SR strain tilapia, which exhibits less than 30% mortality after transferred to 27 ppt sea water (SW) for 24 hr. Microarray analysis was used to compare gill gene profiles between the SR strain and wild type (WT) tilapia after SW transfer. Most of the up-regulated genes are related to energy metabolism, transcription and translation. Quantitative-real time PCR (qPCR) was used to confirm the mRNA expression of some genes selected from the profile list. At 3 hr after SW transfer, the mRNA expression of atp1a1 and slc12a2 was increased in the SR strain that in WT, while that of slc12a3 was reduced in the SR. eno1, a glycolysis gene, was higher in the expression in the RS than in WT. On the other hand, pyruvate and lactate contents in the SR tilapia were higher than those in WT ones. Taken all together, the SR strain of tilapia appear to supply energy and stimulate ion transporters at a better timing and thus survive better than do WT upon SW challenge.