曼氏无针乌贼耗氧率及溶氧胁迫对其体内酶活力的影响

采用Winkler法测定水中溶氧含量，通过比较对照呼吸室与试验呼吸室水中溶解氧含量之差确定曼氏无针乌贼耗氧率及窒息点，并在不同程度的溶氧胁迫下测定乌贼体内多种酶的活力变化.结果表明：曼氏无针乌贼耗氧率呈明显的“高-低-高-低”昼夜变化；耗氧率与水温(16 ℃～28 ℃)和光照(3～500 μmol·m^-2·s^-1)呈正相关，与pH值(6.25～9.25)呈负相关；随着盐度的升高(18.1～29.8)，乌贼耗氧率呈“高-低-高”变化，盐度为24.8时耗氧率最低；雌性乌贼耗氧率高于雄性.窒息点随乌贼的体质量增加而降低，平均体质量为(38.70±0.52) g的乌贼窒息点为(0.9427±0.0318) mg·L^-1.随着溶氧胁迫程度的增加，超氧化物歧化酶(superoxide dismutase, SOD)、过氧化氢酶(catalase, CAT)和过氧化物酶(peroxidase, POD)活力均先升后降，脂肪酶活力下降，蛋白酶活力呈“降-升-降”变化；乳酸脱氢酶(lactate dehydrogenase, LDH)活力呈先升后降趋势，但溶氧胁迫下的酶活力比正常时要高.

Oxygen consumption rate and effects of hypoxia stress on enzyme activities of Sepiella maindron.

The oxygen consumption rate and suffocation point of Sepiella maindroni were determined through the measurement of dissolved oxygen in control and experimental respiration chambers by Winkler’s method, and the changes of S. maindroni enzyme activities under different levels of hypoxia stress were studied. The results indicated that the oxygen consumption rate of S. maindroni exhibited an obvious diurnal fluctuation of ‘up-down-up-down’, and positively correlated with water temperature (16 ℃-28 ℃) and illumination (3-500 μmol·m^-2·s^-1) while negatively correlated with water pH (6.25-9.25). With increasing water salinity from 18.1 to 29.8, the oxygen consumption rate had a variation of ‘up-down-up’, being the lowest at salinity 24.8. Female S. maindroni had a higher oxygen consumption rate than male S. maindroni. The suffocation point of S. maindroni decreased with its increasing body mass, and that of (38.70±0.52) g in mass was (0.9427±0.0318) mg·L^-1. With the increase of hypoxia stress, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) decreased after an initial increase, lipase activity decreased, protease activity had a variation of ‘decrease-increase-decrease’, and lactate dehydrogenase (LDH) activity had a trend of increasing first and decreasing then. The enzyme activities were higher under hypoxia stress than under normal conditions.