Cadmium effects on protamine-like and on DNA oxidative damage in Mytilus galloprovincialis

Heavy metal pollution has become one of the most serious environmental problems. They can make DNA damage, due to their ability to form reactive oxygen species, causing mutations in human cells which may cause tumors. In order to monitor sea levels of heavy metals are used specific bioindicators like Mytilus galloprovincialis whose sperm chromatin is organized by three protamine-like (PLII, PLIII and PLIV), which belong to sperm nuclear basic proteins. We report the effects of Cd2+ on DNA, PLII and PLIII. Both PLII and PLIII acquired a slight proteinase K digestion resistance in the presence of metal. We also analyzed the self-association ability of PLII and PLIII Cd2+mediated. Turbidity assay showed that cadmium caused PLII but not PLIII aggregation, while glutaraldehyde produced a reduction of self-association ability for both proteins. Further, Cd2+ induced a decreasing of PLII DNA binding affinity but an increasing for PLIII and promoted H2O2 DNA damage even in the presence of Protamine-like. Those effects may result in an incorrect chromatin packaging that could decrease Mytilus galloprovincialis’ fitness and that of other marine species exposed to this polluting agent.