The Effects Of Cadmium And Lead On Mitochondria Of Freshwater Crab (Sinopotamon Henanense)

In all kinds of environmental pollution, the pollution in water is especial serious, whose harm is the biggest and most widespread. Heavy metal element, for example cadmium or lead, could be released to the environment by many kinds of way, like mining, smelting, coal burning, automobile exhaust discharging, galvanization industry and so on. In addition, the subsidence of atmospheric dust particle and the washing of rain water to ground , all may cause it to enter in the rivers and streams lake, causes the water body pollution, affects aquatic biological and humanity's activity. Therefore to develop research about aquatic biological pollution is urgent. The crab perches in under water and heavy metal pollution in environment affect it in all probability, so it is also sensitive to the heavy metal pollution. Mitochondrion is one of important sub-organelle in the cell, and in eukaryote mitochondrion is the energical center of cell. Oxidative phosphorylations which react in mitochondria produce energy to the activity of cell, and then it enables each physiological function to complete smoothly in the animal organism. At the same time oxidative phosphorylation of mitochondria is the main way which free radical produces. The damage of mitochondrion induced by free radical may weaken the function of to oxidative phosphorylation, and then it can affect the natural activity of organism. In view of this, this word has studied the damage of cadmium and lead to the mitochondria of S. henanense, by the biochemistry and the molecular biology technology, and then discussed the damage mechanism of heavy metal to mitochondria.The studies were divided into three chapters.Chapter one: The damnification of cadmium and lead on mitochondria of freshwater crab, S. henanenseThis research has been achieved from April to May in 2004. The freshwater crab (S. henanense) were exposed respectively to cadmiumsolution (CdCl2-2.5H2O) or lead solution(Pb(NO3)2). At 96 hour, execute and anatomise the freshwater crab and determine the organs coefficient and mensurate the content of mitochondrion of heart and hepatopancreas, then determine the mitochondrial swelling with the spectrophotometric method. The result showed that, cadmium can make the content of mitochondrion increasing, and cause the swelling degree of mitochondrion to be more serious. The lead could cause the content of mitochondrion in heart and the hepatopancreas to reduce. So it could affect the energy metabolism in organism. The lead could also cause mitochondrial swelling degree increases, with lead concentration increasing, the dose-effect relationship were obvious. It was thought that the abnormal of enzyme metabolism and the damage of the mitochodrion could be that cadmium or lead injured the function of heart and hepatopancreas cell. In addition, the membranous structure of mitochondrion in heart and hepatopancreas cells are easily damaged, which suggested that mitochondria were a sensitive organelle to cadmium and lead.Chapter two: Effect of cadmium and lead on activity of mitochondrial enzyme of freshwater crab, S. henanenseThis research has been achieved from September in 2004 to May in 2005. The freshwater crab (S. henanense) were exposed respectively to cadmium solution (CdCl2-2.5H2O) or lead solution (Pb(NO3)2) . Activity of mono amine oxidase, cytochrome oxidase and malate dehydrogenase in mitochondrion of heart and hepatopancreas were assayed at 24, 48, 72 and 96 hours, with the spectrophotometric method. The result showed that these enzymes' activities all were changed remarkably by cadmium and lead. The activity of mono amine oxidase and cytochrome oxidase increased at first and then decreased remarkably, but the activity of malate dehydrogenase represented degressive first midst and last when by cadmium. When by lead, the change of activity of mono amine oxidase, cytochrome oxidase and malate dehydrogenase in two tissues were uniform and all of these enzymes' activity rised in low concentration and fell in high concentration and thedose-effect relationship was obvious. To sum up, these mitochondrial enzymes were highly sensitive to cadmium and lead. It was thought that the injury of cadmium and lead on heart and hepatopancreas mitochondrion might be due to its direct inhibition on respiratory enzyme activity, and related with oxygen free radicals mechanism. Therefore, mitochondria are damaged earliest, which suggested that mitochondria were a sensitive organelle to cadmium and lead. We could ues the enzyme of mitochondria as a biochemical guideline of crustacean animal in adversity.Chapter three: Damnification of cadmium and lead on mitochondrial DNA of freshwater crab, S. henanenseThis research has been achieved from September in 2005 to March in 2006. The freshwater crab (S. henanense) were exposed respectively to cadmium solution (CdCl2-2.5H2O) or lead solution (Pb(NO3)2). At 96 hour, the crabs were executed, then anatomise and extract the mitochondria in heart and hepatopancreas. Then determine the mitochondrial DNA hyperchromictity, and electrophoreses to analysis of the mitochondrial DNA. The result showed that, cadmium and lead can induce DNA-DNA cross-linking and destroy the DNA. And we can suppose that the effect of cadmium or lead on mitochondrial enzyme activity is due to the damage of cadmium or lead on mitochondrial DNA and its transcription system. These poison effects of heavy metal on mitochondrial DNA may be indirect effects by oxygen free radicals induced by heavy metal or direct effects by the heavy metal itself. Which way is dominant? It is still need a lot of further research.