盐度胁迫对三疣梭子蟹鳃Na+/K+-ATPase酶活的影响

Influence of salinity stress on the activity of gill Na+/K+-ATPase in swimming crab(Portunus trituberculatus)

摘要:

通过钼蓝法测定三疣梭子蟹在3组实验盐度的胁迫过程中第2对和第6对鳃Na⁺/K⁺-ATPase酶活的变化,比较了3组实验盐度胁迫1 d时,鳃Na⁺/K⁺-ATPase的酶活大小。结果表明,在盐度胁迫初期,3组实验盐度下第2对和第6对鳃Na⁺/K⁺-ATPase的酶活下降;之后,各组实验盐度下第2对和第6对鳃Na⁺/K⁺-ATPase的酶活开始随胁迫时间增长而上升;最后,各组实验盐度下第2和第6对鳃Na⁺/K⁺-ATPase的酶活下降并趋于稳定。另外,胁迫1 d时,各组实验盐度下三疣梭子蟹前5对鳃Na⁺/K⁺-ATPase的酶活显著低于后3对鳃Na⁺/K⁺-ATPase的酶活。三疣梭子蟹对盐度变化的调节可分为被动应激期(酶活力下降)、主动调节期(酶活力逐渐上升)和适应期(酶活力稳定);三疣梭子蟹后3对鳃是离子转运、渗透压调节的主要部位。

关键词:三疣梭子蟹; 盐度胁迫; 鳃; Na⁺/K⁺-ATPase

Abstract:

The swimming crab, Portunus trituberculatus,is an important marine fishery and aquaculture species.Water salinity conditions influence its artificial propagations.In order to understand its adaptation mechanisms to environmental salinity changes,we investigated gill Na⁺/K⁺-ATPase activity in the P.trituberculatus exposed to different salinity stresses.Forty-five male adult crabs were divided into 3 groups(15 crabs for one group)and acclimated to three different salinity conditions(10,25 or 40).The 2^nd and the 6^th gills of three crabs from each treatment were sampled on days 0.5,1,2,3 and 5,respectively.In order to compare the Na⁺/K⁺-ATPase activities among different gills of a crab,we sampled all the eight gills from three crabs from each salinity group on day 1.Na⁺/K⁺-ATPase activities were measured by Molybdenum blue spectrophotometric method.Data were expressed as mean and standard error(mean±SD)and one-way ANOVA was used for statistical analysis.The results indicated that the activities of gill Na⁺/K⁺-ATPase in three salinity treatments decreased in the primary period,increased gradually,decreased again and reached a plateau finally.In addition,the Na⁺/K⁺-ATPase activities of the three posterior pairs of gills were remarkably higher than those of the five anterior pairs of gills.Based on these results,we proposed to divide osmotic regulation into three phases:passive stress phase(the decrease of the Na⁺/K⁺-ATPase activities),positive regulation phase(the elevation of the Na⁺/K⁺-ATPase activities)and adaptive phase(the stability of the Na⁺/K⁺-ATPase activities).The three posterior pairs of gills were the main sites of ion transportation and osmotic regulation in P.trituberculatus.This paper revealed the regulations of Na⁺/K⁺-ATPase activities of P.trituberculatus during salinity stress,and facilitated the understanding of physiological and salinity adaptative mechanisms in this species.

Key words:Portunus trituberculatus; salinity stress; gill; Na⁺/K⁺-ATPase