高pH胁迫对克氏原螯虾的急性毒性和鳃、肝胰腺中酶活性及组织结构的影响

Acute toxicity of high p H stress and its effect on enzymes activity and histological structure of gill and hepatopancreas in Procambarus clarkii

研究了高pH胁迫对克氏原螯虾鳃、肝胰腺中酶活性的变化,以及对鳃、肝胰腺组织结构的影响。在得出96 h L C_(50)的基础上,设置对照(pH7.6)和实验(pH10.2)2个pH处理组,进行96 h高pH胁迫,于胁迫后0、2、8、24和96 h测定鳃Na^+-K^+-ATP酶、乳酸脱氢酶(lactate dehydrogenase,LDH)、延胡索酸还原酶(fumarate reductase,FRD)、肝胰腺超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)的活性以及丙二醛(malondialdehyde,MDA)的含量,并采集完整的鳃、肝胰腺做组织切片观察。结果发现,96 h LC50 pH值为10.194。高pH应激后,实验组鳃Na+-K+-ATP酶、LDH和FRD的活性呈上升趋势,pH胁迫8 h后与对照组差异显著(P<0.05);随胁迫时间的延长,实验组肝胰腺MDA含量的变化趋势与LDH和FRD相似,CAT活性呈先上升后下降趋势,SOD活性起初变化不大,pH胁迫24 h后出现明显下降(P<0.05)。鳃和肝胰腺的组织观察表明,随着pH胁迫时间的延长,鳃呼吸上皮细胞逐渐脱落,角质层受损、破裂,鳃叶受损程度逐渐加剧;肝胰腺小管基膜破损,小管内空泡增多、体积增大,肝细胞细胞数量减少。研究表明,高pH胁迫对克氏原螯虾代谢会产生影响,同时导致氧化应激,并会对鳃和肝胰腺的组织结构造成损伤,影响其生物学功能。

In this study, the toxic mechanism of Procambarus clarkii responding to high pH stress was investigated through analyzing the effect of high pH on enzymes activity and histological structure of gill and hepatopancreas.Based on the 96 hours median lethal concentration, Procambarus clarkii were exposed to two pH levels： pH 7.6（control group） and pH 10.2（experimental group）. Each group was respectively sampled for measuring activity of Na＋-K＋-ATPase, lactate dehydrogenase（LDH）, fumarate reductase（FRD） in gill, measuring activity of superoxide dismutase（SOD）, catalase（CAT） and content of malondialdehyde（MDA） in hepatopancreas, and observing the histological structure of gill and hepatopancreas at 0, 2, 8, 24, 96 h. The results showed that the value of pH LC50 was 10.194 at 96 h. Activity of gill Na＋-K＋-ATPase, LDH, FRD in experimental group presented the trend of rising and were significantly higher than those in control group（P〈0.05） after 8 h exposure. With pH stress time prolonging, the variation trend of malondialdehyde content in experimental group was similar to LDH and FRD.Activity of hepatopancreas CAT in experimental group presented the trend of rising firstly and declining afterward.Activity of hepatopancreas SOD was decreased significantly（P〈0.05） after 24 h exposure. Procambarus clarkii exposed to high pH displayed histological alterations in the gill and hepatopancreas. Gill tissues showed respiratory epithelium cells were exfoliated gradually, and cuticle rupture. The hepatopancreas indicated basement membranes of hepatopancreas tubule were ruptured, the enlarged size and increased number of vacuoles in hepatopancreas tubule, and the number of hepatocytes was decreased distinctly. The results indicated that high pH stress will affect the metabolism of Procambarus clarkii and will arouse oxidative stress, The histological structure of gill and hepatopancreas will also be affected by high pH stress, as well as their biological functions.