盐度胁迫对香港牡蛎部分生化指标的影响

Effects of salinity stress on partial biochemical indicators of the Hong Kong oyster Crassostrea hongkongensis

为探究盐度胁迫下香港牡蛎(Crassostrea hongkongensis)生化指标的变化规律,了解盐度适应过程中牡蛎的代谢机制,本研究以盐度0、8、16、32、40 为胁迫盐度,以正常海水(盐度24)为对照,开展香港牡蛎对盐度胁迫的响应研究。结果显示,各实验盐度组糖原含量在盐度胁迫0~8 h 内下降,且盐度胁迫幅度越大糖原含量降幅越大,胁迫8 h 后则无明显的变化规律。腺苷酸激活的蛋白激酶(AMPK)、组蛋白/蛋白去乙酰化酶(SIRT1)和Na^+/K^+-ATP 酶活力的变化规律相似:在0~8 h 内,各实验组酶活力均急剧下降(SIRT1 上升);8~48 h 内,酶活力上升;48~120 h 内,酶活力逐渐趋于平稳状态,总体表现为盐度越高,酶活力越强,并与胁迫前有明显差异,且盐度胁迫幅度越高,差异越明显。总抗氧化能力(T-AOC)总体表现出高盐胁迫下随时间的增加而升高,低盐胁迫下随时间的增加而降低,且盐度胁迫幅度越大, T-AOC 活力的变化幅度越大。实验结果初步表明,香港牡蛎糖原含量与渗透压调节存在一定的关系, AMPK、SIRT1、Na^+/K^+-ATP 酶活力及T-AOC 均与渗透压调节密切相关,且在高盐胁迫下随时间的增加而升高,低盐胁迫下随时间的增加而降低。

The Hong Kong oyster Crassostrea hongkongensis is a commercially important shellfish in southern China that is distributed in areas south to the Yangtze River, primarily in Guangdong and Guangxi provinces. This shellfish is characterized by its large size, high edible value, and breeding profit. Salinity is closely related with the growth and metabolism of aquatic animals, and changes in salinity lead to physiological consequences. This study investigated the changes in the regulation and characteristics of biochemical indicators of the Hong Kong oyster during salinity stress by setting up experimental groups across five salinity gradients (salinity 0, 8, 16, 32, and 40 ppt) and a control group at a salinity of 24 ppt. Samples of the experimental groups were collected at 8, 24, 48, 72, 96, and 120 h, and those of the control group were collected at 0, 8, 24, 48, 72, 96, and 120 h. Glycogen content declined during the 0–8 h period in the experimental groups, and the larger the difference in salinity between the experimental and control groups, the greater was the decline in glycogen content. No obvious pattern of change was detected after 8 h. Changes in the activities of AMPK, SIRT1, and Na+/K+-ATP were similar, and the activity of the enzymes declined rapidly in the experimental groups during the 0- to 8-h period. However, the activity of SIRT1 increased during this period. The activity of all the enzymes increased during the 8–48 h period and became stable after 48 h. The higher the salinity, the greater was the enzyme activity, and the higher the salinity deviated from the normal value, the more obvious was the difference in enzyme activity from the initial state. T-AOC increased with time under high salinity stress and decreased with time under low salinity stress, with a higher deviation of salinity from the normal value leading to a greater range of the change. Thus, it could be concluded that there exists a certain relationship between glycogen content and osmoregulation in the Hong Kong oyster. The activities of AMPK, SIRT1, and Na^+/K^+-ATP and T-AOC were closely associated with osmoregulation;they increased with time under high salinity stress and decreased with time under low salinity stress.