Molecular Ecotoxicological Effects of Typical Persistent Toxic Substances in Bellamya Aeruginosa
|Keywords||Bellamya aeruginosa persistent toxic substances molecularecotoxicological effect biomarker sediment bioassay Na~+ K~+-ATPase MDA HSP70|
The persistent toxic substances (PTS) are a group of chemical pollutants with arelatively high liposolubility, bioaccumulation, carcinogenicity, teratogenicity,mutagenicity, and endocrine disruption, which are not easy to be degraded and canchronically reside in the environment, therefore, PTS have higher toxicity to wildlifeand human. Little is known about the molecular ecotoxicological effects of PTS onbenthic macroinvertebrates. Bellamya aeruginosa is widely distributed in fresh water inChina and mainly dwells in the sediment, and plays an important role in the food chain,can be used as a potential testing organism for freshwater sediment toxicity.Responsive sensitivities of hepatopancreatic Na~+, K~+-ATPase, malondialdehyde(MDA) and heat shock protein70family (HSP70) in B. aeruginosa to three typical PTS(heavy metal Cd, polybrominated diphenyl ethers (BDE-47), and CuO nano-particles(CuO-NPs)) were investigated through bioassay via natural sediments artificially spikedwith above three chemicals to explore potential molecular ecotoxicological mechanismsof PTS stress on B. aeruginosa, and to evaluate the potential of Na~+, K~+-ATPase、MDAand HSP70used as molecular biomarkers for indication of PTS-contaminated sediment.The results showed that, under three typical PTS stress, three molecular biomarkersdisplayed significant concentration-and time-effect relationships. After exposed toCd-contaminated sediments, Na~+, K~+-ATPase activites first increased then decreased. Inthe low concentration treatments, MDA content displayed an initial increase, then felled,and afterwards significantly rise, in the high concentration treatments, MDA contentincrease to a relatively high levels during late exposure periods. HSP70expression inlow concentration treatments showed time-dependent increase, at high concentration,HSP70expression were first induced and then inhibited. The hepatopancreatic Na~+,K~+-ATPase, MDA and HSP70in B. aeruginosa can be used as effective molecularbiomarkers for indication of Cd stress from sediments. After exposed toBDE-47-contaminated sediments, Na~+, K~+-ATPase activites in the low concentrationtreatments showed time-dependent increase, at high concentration, Na~+, K~+-ATPaseactivites first induced and then inhibited. MDA content first increased and thendecreased, finally directed toward stable levels. The short-term exposure with highconcentration of BDE-47caused significant HSP70induction, the long-term exposurewith different concentrations of BDE-47significantly decease HSP70expressioncompared to the controls. MDA may effectively indicate short-term exposure under lowconcentration of BDE-47, Na~+, K~+-ATPase activites and HSP70expression can indicatelong-term exposure under low concentration of BDE-47. After exposed toCuO-NPs-contaminated sediments, Na~+, K~+-ATPase activites displayed an initialinduction and subsequent inhibition with prolonged exposure duration. MDA contents at low concentration of CuO-NPs first increased and then decreased, in the highconcentration treatments, MDA contents showed a trend of high-low-high-low. Theshort-term (3d) exposure with different concentrations of CuO-NPs caused a dramaticincrease of HSP70expression, long-term exposure had no effect on HSP70expression.The hepatopancreatic Na~+, K~+-ATPase and MDA showed a good responsive sensitivityto CuO-NPs stress, whereas HSP70only responded to CuO-NPs stress within shortexposure duration, therefore, HSP70is not an effective molecular biomarker forindication of long-term CuO-NPs stress.In this study, the concentration-and time-effect relationships between threebiomarkers (Na~+, K~+-ATPase, MDA and HSP70) and three PTS (Cd, BDE-47andCuO-NPs) were established through sediment bioassays. The obtained results will be ofimportant theoretical significance and practical value for reasonable ecotoxicity riskassessment of PTS in the sediments and the development of bioassay methods using B.aeruginosa.