Study On The Enrichment Regularity And Response Mechanism Of Cadmium In Oratosquilla Oratoria

Cadmium was one of the main pollutants in aquatic products,which can be enriched by aquatic products,and cause harm to human.Because of high cadmium content was detected in Oratosquilla oratoria,the accumulation and response mechanism of Oratosquilla oratoria to cadmium in seawater were studied.The specific accumulation mechanism of cadmium in was analyzed by studying the distribution characteristics of cadmium in different tissues and subcells.By measuring the activities of SOD and CAT and the content of MDA,the effects of cadmium on antioxidant enzyme system were studied to reveal the toxic effects of cadmium in Oratosquilla oratoria.By analyzing the changes of MT content in different tissues,the relationship between the accumulation of cadmium and MT content in different tissues of Oratosquilla oratoria was compared.Specific results were as follows:(1)The tissue distribution of cadmium in Oratosquilla oratoria:simulated culture test and ICP-MS method were used to analyze the accumulation of cadmium in muscle,gonad and digestive tract in Oratosquilla oratoria,compare the accumulation ability of cadmium in each tissue,and determine the main accumulation and distribution tissue of cadmium in Oratosquilla oratoria.The result show that,the accumulation of cadmium in muscle,digestive tract and gonad of Oratosquilla oratoria increased with the exposure time and concentration.The enrichment rate of all tissues showed a trend of faster accumulation in the early stage and slower accumulation in the middle and late stage.The digestive tract was the main tissue of cadmium accumulation,and the content and enrichment rate of cadmium in the digestive tract are significantly higher than that in the muscle and gonad.The accumulation of cadmium in gonads of male Oratosquilla oratoria was higher than that of female,and the concentration of cadmium in muscle and digestive tract was similar.The two-chamber dynamic model was used to nonlinear fit the accumulation of cadmium in different tissues,and the mathematical model of nonlinear fit between the accumulation of cadmium in Oratosquilla oratoria and the concentration,time,rate constant,etc.,was established to obtain the enrichment kinetic parameters of cadmium in Oratosquilla oratoria.The results showed that,the BCF of in tissues of Oratosquilla oratoria ranged from 57 to 2157,which the BCF of digestive tract was more than 500.Except for the cadmium in the gonad of the female Oratosquilla oratoria in the low concentration group,the C_max of each tissue did not reach the equilibrium.The Cmax of tissues Oratosquilla oratoria were digestive tract>muscle>gonad in female,digestive tract>gonad>muscle in male.(2)The subcellular distribution of cadmium in Oratosquilla oratoria:the Cadmium in muscle and digestive tract subcells of Oratosquilla oratoria was analyzed by differential centrifugation and ICP-MS,to investigate the subcellular distribution of cadmium in different tissues.The result show that,the accumulation of cadmium in subcells muscle and digestive tract of Oratosquilla oratoria increased with the exposure time.The MTLP was the main subcellular component of cadmium in muscle and digestive tract,and the content of cadmium were MTLP>HSP>CD>ORG>MRG in muscle,MTLP>HSP>ORG>CD>MRG in digestive tract.With the exposure time,the proportion of MTLP cadmium in subcellular showed an increasing trend,while that of HSP showed an decreasing trend,CD,ORG and MRG had no obvious changes.The cadmium was combined with MTLP and HSP to reduce the injury of Oratosquilla oratoria.(3)The effects of cadmium on antioxidant enzyme activity in Oratosquilla oratoria:the activities of SOD and CAT and the content of MDA were determined by spectrophotometry and chemical method,to analyze the effects of cadmium on antioxidant system of Oratosquilla oratoria.The result show that,the effects of SOD and CAT activity in different tissues were different,but the effects on MDA content were similar.In the low concentration group,SOD activity in the muscle of Oratosquilla oratoria showed a tendency of first induction and then inhibition,the digestive tract showed a tendency of mainly inhibition,and the gonad and eyeball showed a tendency of mainly induction.In the medium concentration group,SOD in the muscle of Oratosquilla oratoria showed a tendency of first induction and then inhibition,and the digestive tract,gonad and eyeball showed a tendency of mainly inhibition.In high concentration group,SOD activity in muscle,digestive tract,gonad and eyeball of Oratosquilla oratoria was mainly inhibited.CAT activity in muscle and digestive tract of Oratosquilla oratoria in low,medium and high concentration groups showed a trend of induction,which was firstly increased and then decreased.The CAT activity in gonad and eyeball of Oratosquilla oratoria was low,and there was no obvious rule among different concentration groups.MDA content in Oratosquilla oratoria increased with the expose time and concentration,and was higher than control group.Under the conditions of this study,MDA content in digestive tract and muscle increased more than that in gonad and eyeball.Cadmium can induce the synthesis of SOD and CAT to reduce the damage of free radicals in Oratosquilla oratoria.Cadmium can induce the synthesis of SOD and CAT and reduce the damage of free radicals in Oratosquilla oratoria.(4)The effects of cadmium on MT content in Oratosquilla oratoria:The changes of MT content in different tissues of Oratosquilla oratoria were determined by mercury saturation method to study the change of MT in Oratosquilla oratoria.The result show that,Cadmium can induce MT production in muscle and digestive tract of Oratosquilla oratoria,and MT content in muscle and digestive tract of Oratosquilla oratoria increased with the exposure time.The MT in muscle and digestive tract of high concentration group was higher than control group.Under the same conditions,the content of MT and the ability to induce MT in digestive tract were higher than that in muscle.The trend of MT content in muscle and digestive tract of Oratosquilla oratoria was consistent with the accumulation of cadmium and the distribution characteristics of MTLP combined with cadmium.The cadmium in digestive tract and muscle of Oratosquilla oratoria was completely bound by MT.