Studies On Behavior Of Heavy Metal Pollutants In The Freshwater Shrimp Macrobrachium Nipponense

The distribution and accumulation of three kinds of heavy metals including lead, copper and mercury in tissues and cells of several organs, and their effects on activity of digestive enzymes and alkaline phosphatase of Macrobrachium nipponense were studied with light microscopy, transmission electron microscopy, cytochemical method, atom absorption spectrum, mass spectrum analysis and enzyme analytical method. The main results were presented as following:1. A lot of lead granules were primarily deposited in the antennal gland. Under transmission electron microscopy, lead granules deposited in lysosome, then accumulated gradually in the apex of the cells, and finally were individually discharged into the gland lumen by apocrine secretion and excreted with the urine. There were small quantities of lead granules in the cells of midgut. A lot of vacuolus occurred in the cytoplasm of the cells. The nuclear membranes and cristae in mitochondria were disintegrated partially. The structure of the cells of hepatopancreas remained intact, although there were a few of lead granules in the cells. No lead granule was found in the cells of gills. Among the gill filaments, however, a few of lead granules adsorbed on the surface of gill filaments. The highest concentration of lead was found in antennal gland by atom absorption spectrum, which suggested that the antennal gland might play an important role in detoxifying process of lead.2. Lots of copper granules were primarily deposited in hepatopancreas tubules and R cell of the hepatopancreas, and accumulated copper granules were distributed in haemocyte space. Under transmission electron microscopy, copper granules were primarily deposited in the lysosome of hepatopancreas cells, and a little amount of copper granules was absorbed in smooth surfaced endoplasmic reticulum. The coppergranules were excreted to the lumen by apocrine secretion. There were copper granules in the cells of midgut. A lot of vacuolus occurred in the cytoplasm of the cells. The cristae in mitochondria were disintegrated partially and copper granules were absorbed into mitochondria. A little amount of copper granules were deposited in the lysosome of the cells of antennal glands, and endoplasmic reticulum was curved in the cells. The highest concentration of copper (546.39 mgkg-1) was found in hepatopancreas by atom absorption spectrum, which indicated that the hepatopancreas might play an important role in storing copper.3. A lot of mercury granules were found primarily in antennal gland by transmission electron microscope and mass spectrum analysis. Mercury granules were found in the lysosome of the cell of antennal gland, and were transited to lumen by apocrine secretion. No mercury granules deposited in the hepatopancreas. There were a few of mercury granules in the cells, and the structure of the cells of midgut was damaged. The highest concentration of mercury was found in the antennal glands by mass spectrum analysis.. 4. Both 0.034-0.3 mg L-1 Cu2+ and 0.2-0.8 mg L-1 Pb2+ influenced significantly the activities of digestive enzymes and alkaline phosphatase. 0.2-0.6 mg L-1 Zn2+ affected markedly the activities of pepsin and trysin-like, but did not influence that of alkaline phosphatase. The relationships between the activity of pepsin (Y, U-mg"1) with Pb2+, Cu2+ and Zn2+ concentrations (X, mg-L"1) were all curvilinear, with the regression equation Y=6.668X2-8.729X+4.439, Y=-3.291X2-8.258X+ 4.941 and Y=-5.113 X2-2.275X+1.140, respectively. And the relationships between the activity of try sin-like (Y, U-mg"1) and Cu2+concentration (X, mg L-1) was also curvilinear, with the regression equation Y=27.799X2-11.711X+1.700.