Immune responses and ultrastructural changes of hemocytes in freshwater crab Sinopotamon henanense exposed to elevated cadmium

Cadmium (Cd) is one of the most toxic heavy metals that can impact immunological parameters in aquatic animals. To investigate the immunotoxicity and ultrastructural changes of hemocytes, specimens of Sinopotamon henanense were exposed to different concentrations of cadmium and the differences in immunologic parameters between Cd exposure groups and control groups were investigated. Total hemocyte count (THC) in Cd-exposure groups were decreased significantly when compared with the control groups, especially in the groups treated with higher Cd concentrations and longer exposure time, while no significant differences were observed in the proportions of the three types of hemocytes. Phenoloxidase (PO) activities were significantly higher in Cd-exposure groups than the control groups. Superoxide dismutase (SOD) activities gradually increased in 7.25 and 14.5 mgL(-1) Cd groups, but in other higher Cd groups, they showed first increase and following decrease with the exposure time prolonged. Acid phosphatase (ACP) activities were induced at 48 h, and then decreased, while alkaline phosphatase (AKP) activities increased gradually until 96 h. Electron microscopic results showed that nucleus, mitochondria and rough endoplasm recutulum (rER) of three types of hemocytes were sensitive to acute Cd toxicity. In Cd-exposed groups, chromatin condensation, nucleus deformation and nucleus envelope rupture were noted. Additionally, mitochondrial dilation and rER degranulation were observed in Cd-treated crabs. These results suggested that immune response and organelles of hemocyte of S. henanense were impacted by Cd exposure, and the changes of these immunologic parameters reflect changes in crab immune response capability consequent to Cd exposure. (C) 2011 Elsevier B.V. All rights reserved.

镉（Cd）是毒性最强的重金属之一，可影响水生动物的免疫参数。为了研究血细胞的免疫毒性和超微结构变化，将河南华溪蟹（Sinopotamon henanense）样本暴露于不同浓度的镉中，并研究了镉暴露组和对照组之间免疫参数的差异。与对照组相比，镉暴露组的总血细胞计数（THC）显著降低，尤其是在镉浓度较高且暴露时间较长的组中，而三种类型血细胞的比例没有显著差异。镉暴露组的酚氧化酶（PO）活性显著高于对照组。超氧化物歧化酶（SOD）活性在7.25和14.5 mg/L镉组中逐渐升高，但在其他镉浓度更高的组中，随着暴露时间延长，其活性先升高后降低。酸性磷酸酶（ACP）活性在48小时被诱导升高，随后降低，而碱性磷酸酶（AKP）活性逐渐升高直至96小时。电镜结果显示，三种类型血细胞的细胞核、线粒体和粗面内质网（rER）对急性镉毒性敏感。在镉暴露组中，观察到染色质凝聚、细胞核变形和核膜破裂。此外，在镉处理的蟹中还观察到线粒体肿胀和粗面内质网脱颗粒现象。这些结果表明，河南华溪蟹的免疫反应和血细胞的细胞器受到镉暴露的影响，这些免疫参数的变化反映了镉暴露后蟹免疫反应能力的变化。（C）2011爱思唯尔有限公司。版权所有。