Studies Of The Immunotoxicities Of Cadmium On Freshwater Mussel(Anodonta Woodiana)

The aim of this study was to investigate the effect of cadmium(Cd²⁺)on immuntoxicity of gill,digestive gland and hemolymph of freshwater mussel?Anodonta woodiana?.The freshwater mussels were exposed to different concentrations of Cd²⁺?0,0.5,5 and 50 mg/L?for 14 days,according to the LC₅₀0 of Cd²⁺within 96 h?134.9 mg/L?.The histological changes in the gill and digestive gland of the freshwater mussels,exposed to 0,0.5,5 and 50mg/L cadmium for 14 d,were measured by making paraffin section stained with hematoxylin-eosin.The activities of PO?phenoloxidase?and LSZ?lysozyme?and the mRNA expression of IKK,I?B and NF-?B in the gills,digestive glands and hemolymph were analyzed in different treatment period?1,4,7 and 14 d?.The results showed that:?1?With the Cd²⁺ concentration increasing,gill epithelial cell became swelling,nuclear dissolved,phagocytic cell increased and edema of connective tissue.Structure of digestive gland was damaged and cylindrical epithelium fell off.?2?The activities of LSZ in the gills were decreased during the Cd²⁺exposure period,while the activities of LSZ in the digestive glands were increased notably?P<0.01?only at 7 d,50mg/L and 14 d,5mg/L.The activities of LSZ in the hemolymph were induced prominently?P<0.05,P<0.01?at 1 and 4 d.While,there was no significant difference at 7 and 14d.The PO activities were gradually declined with the extension of treatment period in the gills and digestive glands,the PO activities in haemolymph were decreased with Cd²⁺concentration increasing.?3?The mRNA expression of IKK,I?B and NF-?B in gills were increased at first and then decreased,with the Cd²⁺exposure time prolonging.In the digestive glands,the mRNA levels of the IKK,I?B and NF-?B were decreased in different concentration groups,except the mRNA expression of IKK and I?B were increased at first and then decreased in 50mg/L Cd²⁺group.The mRNA expression of IKK,I?B and NF-?B in hemolymph were almost decreased.It is indicated that:?1?Cadmium stresses affected the histological structure of Anodonta woodiana,and showed the obvious relationship between dose and effect.?2?Cadmium stresses affected the immune defense system of Anodonta woodiana,LSZ and PO activities can be used as biochemical indexes of environmental monitoring.?3?The mRNA expression of immune-related genes in the gills,digestive glands and hemolymph were affected by cadmium stresses.