马度米星铵对克氏原螯虾鳃组织的毒性

Effect of maduramycin ammonium on the gill tissue of crayfish

旨在研究马度米星铵对克氏原螯虾鳃组织结构和抗氧化系统的影响。首先采用24 h换水式生物试验研究了马度米星铵对克氏原螯虾96 h急性毒性,在此基础上,设定低（0.7 mg/L）、中（3.5 mg/L）、高（7.0 mg/L）3个马度米星铵剂量组和一个空白对照组,暴露28 d。分别在第7、14和28天从每组随机抽取6只克氏原螯虾,测定鳃组织超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量（以每毫克蛋白计）,并在28 d时做鳃组织HE染色观察结构变化。结果显示：马度米星铵对克氏原螯虾96 h半数致死浓度（LC50）为70.08 mg/L,95%置信限为58.95-83.31 mg/L。与空白对照组相比,SOD活性中、高剂量组主要表现为先下降后逐渐恢复,低剂量组则是逐渐下降（P〈0.01）;各剂量组CAT活性7 d时稍有上升后逐渐下降,28 d时,各剂量组CAT活性显著低于空白对照组（P〈0.05）;中、高低剂量组MDA含量变化趋势先升高后下降,低剂量组与空白对照组相比则无显著变化（P〉0.05）。各剂量组鳃组织可见明显病理变化,上皮细胞脱落、呈碎片化,微血管腔结构消失,鳃膜结构受损。研究表明马度米星铵对克氏原螯虾为低等毒性。0.7、3.5和7.0 mg/L马度米星铵均可诱导克氏原鳌虾鳃组织的氧化应激,并引起鳃组织结构的严重损伤。

This study was to study the effect of maduramycin ammonium on the antioxidant system in and of the tissue structure of gill in crayfish. Acute semi-static toxic test was first performed. Then, crayfish were exposed to maduramycin ammonium at concentrations 0. 7 mg · L-1 , 3.5 mg · L-1 and 7.0 mg · L-1 for 7, 14 and 28 days, respectively. Antioxidant parameters and oxidative stress [ malondialdehyde （MDA） ] on gills, and injury of gill tissue, were measured. The 96-hour median lethal concentration （96 h LC50） after initiation of cray- fish being exposed to maduramycin was 70. 08 mg · L-1 with a 95% confidence interval between 58.95 and 83.31 mg ·L-1. Compared with the control group, the SOD activity in gills decreased at 7th and 14th days, but increased after 28 days of exposure at the medium and high concentrations. The SOD activity at the low concentration decreased consistently during exposure （P〈0. 01 ）. The CAT activity in gills at all the tested concentrations rose at 7th day, and then declined at 28th day significantly （P〈0.05）. The MDA content in gills increased first, but then decreased at the medium and high concentrations, while no changes were observed at the low concentration （P〉0. 05）. At 28th day, sig- nificant pathologic changes were observed in all the groups of maduramicin-treated gills. The epithelial cells in gills fragmented and exfolia- ted, the microvascular cavity disappeared, and the gills membranes were impaired. The above results indicated that maduramycin was lowly toxic to crayfish. The doses of 0. 7 mg · L-1 , 3.5 mg · L-1 and 7.0 mg · L-1 maduramycin ammonium all induced oxidative stress and tissue injury in the gill of crayfish.