Interactions Between Metal Ions And DNA Of Fish

Heavy metal contamination is one of the most fishery environmental pollution in recent years and the situation is very serious. Some heavy metal ions, such as Cd2+, Hg2+, Pb2+ and so on, have strong genetic toxicity. They go into fish and enrich in the food chain, lead heavy metal toxicosis, seriously decrease the output and at last harm people's health. But the poisonous mechanism of heavy metal remains still unclear, especially the mechanism of DNA chain's fragmentation and untwisting, which is one of the major characters of apoptosis made by acute injury, still needs more researches. And how to relieve the toxicity of heavy metal in fish has been rarely reported. It is well known that calcium (Ca) is an essential element to organisms; rare earth elements (REEs) also have extensively biological effects on plants, animals and human beings in the biosphere. So we studied the direct and indirect interactions among heavy metal ions, such as Cd2+, Hg2+ and Pb2+, rare earth ions, such as La3+ and Ce3+, Ca2+ and fish DNA, trying to clarify the poisoning mechanism of fish DNA caused by heavy metal from physiological and biochemical level, investigate whether calcium and REEs could reduce the toxic effect of fish DNA caused by heavy metal, providing an important theoretical basis for preventing the environment pollution.Three main aspects are involved.(1) Direct interaction between Pb2+ and fish intestinal DNA was studied. Ultraviolet absorption spectra showed that as the addition of Pb2+, the characteristic peak of fish intestinal DNA at 260 nm decreased, meanwhile, the peak of DNA at 207 nm obviously blue shifted, which indicated that the strong bonding action happened between Pb2+ and DNA. Fluorescence emission spectra showed that with the addition of Pb2+, the fluorescence emission peak didn't obviously change while the fluorescence intensity reduced gradually, indicating that Pb2+ didn't obviously change the polarity environment of DNA fluorescence chromophore, but it could cause the intrinsic fluorescence quenching of DNA, and the quenching was static quenching. Vacuum ultraviolet circular dichroism...