Toxicity And Bioaccumulation Of Sulfamethazine In Oryzias Melastigma

The antibiotics are commonly used in aquaculture and livestock farming for its broad-spectrum antibacterial properties and growth promoter,but the antibiotics are excreted to the aquatic and marine environment in parent and metabolite via animal manure without effective supervision,which will threaten the growth and development of aquatic organisms and marine life,and cause biochemical physiological toxicity.Among various antibiotics sulfonamide was frequently detected in the environment.So,sulfamethazine(SM2)and acetylated metabolites(N-SM2)were selected as representative compounds and marine medaka(Oryzias melastigma)was selected as testing organism.We investigate the discrepancies between long-term exposure and short-term exposure on the bioconcentration,and metabolism of sulfamethazine,and to explore the mechanism of toxicity from biological response(SOD,CAT)and Proteomics.The study also helped to provide information for current environmental monitoring and risk assessment of SM2 The main results in this thesis were as follows.1)Under the short-term exposure,the uptake of SM2 was affected by the pH changes in the micro-environment between the gill and the water.The BCF value suggested that bile and gonad were the major sites of tissue storage of SM2 and N-SM2.What's more,a gender difference can be observed in the bioconcentration and antioxidant enzyme activities.2)Under the long-term exposure and water recovery,there was no significant difference in gender and exposure concentration,and there was a higher concentration and BCF value at 14 d.In the absorption process,the SM2 might metabolite with acetylation or hydroxylation metabolism.Moreover,the liver and gonad were the two major target organ.And there was still a high concentration of parent and metabolite after water recovery.3)The metabolite and antioxidant enzyme were significantly affected by the long-term exposure of SM Besides,many important processes/pathways were significantly suppressed by SM2 in marine medaka,such as protein translation,synthesis,energy metabolism,nucleic acid synthesis and vitellogenin.The disorder expression of energy metabolism and vitellogenin are the two main influence ways.In addition,the expression of protein in marine medaka and its corresponding function will be changed with the exposure time and conditions,and the recovery process of functional protein was also inhibited by the energy metabolism during the recovery period.