| The freshwater crab is widely distributed in Chinese freshwater area, while the Sinopotamon yangtsekiensei is a kind of representative one of the freshwater crab. Effects of heavy metal, such as Hg2+, on the species can reflect the effects of the water pollution of heavy metal on the Decapodas (Crustacea) to some extent.Based on the level of cell and molecule, effects of mercury on organs of S.yangtsekiense had been studied in this paper.There are four sections in this experiment.Section â… : Laboratory experiment was carried out to determine mercury accumulation in four organs that were gills, heart, hepatopancreas and gonad of freshwater crab Sinopotamon yangtsekiense by using atomic absorption method. The male crabs were subjected to different concentrations of Hg2+ (0mg/L, 0.0547 mg/L, 0.1727 mg/L, 0.5457 mg/L and 1.7244mg/L) for 24h, 48h and 72h.The results showed that the total bioaccumulation of mercury in the four organs of the crabs were very different. Among them, mercury was accumulated strongly in the gill, followed by the heart, hepatopancreas and gonad. The bioaccumulation of Hg2+ in S.yangtsekiense had the concentration - effect relationship, that was to say ,the more the concentration increased ,the more the bioaccumulation increased. At the high mercury concentration, there was more obvious the time - effect relationship being observed. The study about S.yangtsekiense, which had the aquatic specificity and was widely scatted, not only guide in medicine, aquatic product and breeding, but also benefit to environmental monitoring, health protection and health nutrient.Section â…¡: After an experimental exposure to Hg2+ ( 0. 55mg/L[Hg2 ] ) for 48 days, the changes of Hg2+on ultrastructure of the myocardial cells of the freshwater crab Sinopotamon yangtsekiense ( )at three different times was studied. Sixty freshwater crabs( ) were divided into two groups: control (n=30) and test (n=30) groups. The test(n=30) group was exposed to Hg2+ (0. 55mg/L[Hg2+] ) while the control crabs were in water without mercury. During the 12d,28d,48d, the ultrastructure of the myocardial cells was observed by using transmission electro-microscopy(TEM).During the early treatment time, nuclear outer membrane was swelling, nucleolus was located near the nuclear membrane, mitochondrions were fused intoa mitochondrial ball, myofibril was expanded partly. With the increasing treatment time, the nuclear outer membrane was dispersed partly. Nucleolus was located on the center, even broken. Some mitochondrial membrane was partly distintegrated, some black granules appeared. Some mitochondrions were vesicling. Myofibril was broken.Section â…¢: This paper dealed with the effects at different concentrations of Hg2+ on the esterase isoenzyme (EST) of the gill, heart ,hepatopancreas and gonad in freshwater crab Sinopotamon yangtsekiense by using polyacrylamide gel electrophoresis(PAGE).The crabs were exposed one week. The concentrations of mercury were Omg/L, 0.0547 mg/L, 0.1727 mg/L, 0.5457 mg/L and 1.7244mg/L.The results showed that the effects of EST isoenzyme activity were not only the activation, but also the inhibition as well in gill, heart and hepatopancreas. EST isoenzyme activity was inhibited mostly in gonad, which damage the gonad in potential under the treatment of mercury. From this result it can be concluded that the EST isoenzyme was very sensitivity for the toxication of Hg24 and can be used as a bioindicator of the environmental pollution .The same experiment had been done twice in 2003.Scetion â…£: From October in 2002 to October in 2003, by using random amplified polymorphic DNA (RAPD), the effects on ovary's DNA under different concentration of mercury in freshwater crab (Sinopotamon yangtsekiense) were detected for the first time. The concentrations of mercury were 0 mg/L, 0.1727mg/L, 0.3713 mg/L, 0.7984 mg/L and 1.7166 mg/L. The crabs were dissected respectively after one week of treatment, and the ovaries were kept in 70% ethanol with 50mmol/L EDTA. Then the DNA which were e...
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