低pH胁迫对克氏原螯虾鳃和肝胰腺酶活力及组织结构的影响

Acute toxicity of low-pH stress and its effect on enzyme activity and histological structure of gill and hepatopancreas in Procambarus clarkii

采用石蜡切片技术,结合生物酶的测定,以体重(25.88±4.40)g的克氏原螯虾(Procambarus clarkii)为研究对象,研究了低pH胁迫对克氏原螯虾鳃和肝胰腺生理代谢与组织结构的影响。在得出96 h LC50的基础上,将克氏原螯虾暴露于半致死浓度pH水体中96 h,以pH7.6作为对照,并于胁迫后0 h、2 h、8 h、24 h、96 h采集鳃和肝胰腺样品,测定鳃部分代谢酶和肝胰腺主要抗氧化指标,并对鳃和肝胰腺组织进行切片观察。实验结果表明,pH 96 h LC50为3.675。低pH暴露后,实验组鳃Na^+-K^+-ATP酶和乳酸脱氢酶(lactate dehydrogenase,LDH)活力逐渐升高,细胞色素氧化酶(cytochrome oxidase,COO)活力逐渐下降;肝胰腺超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT)活力呈现先上升后下降的变化趋势,丙二醛(malondialdehyde,MDA)在肝胰腺中的累积量显著增加(P<0.05)。切片结果表明,低pH胁迫引起克氏原螯虾鳃组织中呼吸上皮细胞逐渐脱落,角质层受损;肝胰腺组织中B细胞及其内部转运泡体积增大,转运泡内颗粒物质增多,肝小管结构受损。研究结果表明,低pH胁迫会对克氏原螯虾生理代谢产生影响,并引起组织缺氧;虾体氧化防御功能在胁迫前期被诱导激活,但在胁迫后期受到一定抑制;低pH胁迫可以引起克氏原螯虾鳃和肝胰腺组织结构损伤。

This study examined the effect of low-pH stress on physiological metabolism and the histological structure of gill and hepatopancreas in Procambarus clarkii with the body weight of （25.88±4.40） g, using paraffin section technology and the measurement of biological enzyme activity. Based on the 96 h median lethal concentration （LC50）, P. clarkii were exposed to pH LC50 water for 96 h. A control group of the species was also exposed to water of pH 7.6. Each pH level was sampled to measure the activity of metabolic enzymes in the gill and antioxidant properties in the hepatopancreas, and the histological structure of gill and hepatopancreas was observed at 0 h, 2 h, 8 h, 24 h and 96 h. The results showed that the value of pH LC50 was 3.675 at 96 h. The activity of Na^＋-K^＋-ATPase and lactate dehydrogenase （LDH） in gills of the experimental group gradually increased, while activity of cytochrome oxidase （COO） in the gill showed the opposite trend after low-pH stress. As pH stress time was prolonged, the activity ofhepatopancreas superoxide dismutase （SOD） and catalase （CAT） in the experimental group increased at first, then declined. The MDA content in the experimental group increased consistently during the exposure time （P〈0.05）. Observation of gill microstructure sampled from P. clarkii exposed to low-pH water （pH 3.6） showed impairment of cuticle and exfoliation of respiratory epithelium cells. Observation of hepatopancreas microstructure sampled from P. clarkii exposed to low-pH water （pH 3.6） indicated the appearance of more B cells and inter-transferred vacuoles in the hepatopancreas tubules, which were enlarged. I am not sure I have understood your intention correctly, so please check carefully. It also showed that the number of granular materials in the transferred vacuoles hadincreased and that the structure of the hepatopancreas tubules was impaired. The study indicated that low-pH stress will affect the physiological metabolism and lead to hypoxia. Antioxidant activities by P. clarkii will be induced by short-term pH stress but inhibited when exposure time is prolonged. Low-pH stress will damage the structure of both gill and hepatopancreas.