低盐处理对长牡蛎胚胎发育及氧化应激、能量供应和渗透调节相关酶的影响

Effect of Hypotonic Induction on Embryonic Development,Energy Metabolism,Oxidation Resistant and Osmoregulation in Pacific Oyster Crassostrea gigas

为探究低盐诱导对长牡蛎(Crassostrea gigas)胚胎发育和发育初期的氧化应激、能量供应及渗透调节的影响。实验观察了低盐诱导组和对照组胚胎到达不同发育时期所用的时间以及发育初期部分酶活力的变化。研究显示,在40%~50%受精卵出现第一极体时,用盐度4~12的低盐海水处理长牡蛎受精卵15 min会导致其胚胎发育明显迟缓,且诱导盐度越低,发育速度越慢,最慢(盐度4)比对照组(盐度32)到达D形幼虫的时间滞后了4 h以上。同时,用盐度8处理15 min后,受精卵的丙酮酸激酶(Pyruvate kinase,PK)和Na^+-K+-ATP酶水平显著降低,总抗氧化能力(Total-antioxidant capacity,T-AOC)水平显著升高(P<0.05),谷草转氨酶(Glutamic oxalacetic transaminase,GOT)水平无显著变化(P>0.05);转入自然海水中恢复1.5 h后,四细胞期胚胎丙酮酸激酶、Na^+-K^+-ATP酶水平恢复到与对照组无显著差异,T-AOC水平回落至接近对照组水平,而谷草转氨酶水平无明显改变。说明低盐胁迫可能会导致长牡蛎受精卵糖代谢受阻,渗透调节紊乱,同时受到较严重的氧化胁迫,且这些改变在转入自然海水一定时间后即可恢复,不会对胚胎发育产生持续性影响,而GOT表达水平则始终无明显变化。研究结果表明,低盐诱导不仅会导致牡蛎受精卵胚胎发育迟缓,还可能会使其受到严重的氧化胁迫,同时阻碍其代谢功能和渗透调节。

The embryonic development and activities of energy metabolism,oxidation resistance and osmoregulation relevant enzymes of the Pacific oyster were investigated in this study to provide insights into the impact of hyposaline triploid induction.After a 15 min hypotonic treatment,development of the zygotes was significantly obstructed with the decreasing of salinity;the 4 treatment groups retarded at least 3 h compared to the control.Besides,when treated at the low salinity of 8 for 15 minutes,the activities of pyruvate kinase(PK)and Na^+-K+-ATPase were significantly reduced and the total antioxidant capacity(T-AOC)was markedly induced while no significant change was observed in glutamic oxalacetic transaminase(GOT).These results indicated that hyposaline induction not only dramatically affected the energy supply by glycometabolism,but also induced severe oxidative stress and disordered osmotic regulation in zygotes of the Pacific oyster.After recovering in the natural seawater for 1.5 h,all of the three enzymes showed a significant tendency to return totheir normal levels,suggesting that these changes didnot exert a longterm impact on the development of the embryos.