| Roxarsone is a kind of organic-class feed additive that has been used for anticoccidial and antibacterial, as well as its growth-promoting properties, which is widely-used in our country. After intake of roxarsone, its residues was low level and accumulated in the body a short time, and absorbed less in the gastrointestinal tract in livestock and poultry. Most of roxarsone was excreted in vitro through feces and urine in prototype directly. Veterinary medicine entered into the environment by the of waste livestock and poultry, can not only affect the ecological environment, can also produce potential threat to human health through food chain enrichment. This study took soil nematodes and C. elegans as the biological indicator, and study on community structure of soil nematode and toxicity of C. elegans during roxarsone exposure, which help for ecological toxicity effect evaluation and risk assessment in the environmental of exposure to roxarsone.The effect of roxarsone on soil nematode community structure was studied using a potted plant simulation test. We tested the effects of 0, 15, 75, and 150 mg roxarsone per kilogram dry soil during the critical period of growth in rape. The experimental results showed that, the response of different nutritional groups in soil nematodes to roxarsone was more obvious during plant maturity. Ecological indices also reflected the effects of different concentrations. During stem elongation, the total arsenic content in soil was significantly correlated with the ? value of dominance index. During plant maturity, the total soil arsenic content significantly correlated with the PPI value of plant parasite maturity index and the ratio of PPI and MI.This study took C. elegans as the experimental animal, during roxarsone exposure, the toxic effect of roxarsone was detected using related evaluation index. The index included 24 h mortality, body bends, head thrashes of first- and second-generation C. elegans, spawns, generation time, time of half lethal and life span of first-generation C. elegans. The damage effect on DNA in embryonic cells and the effect on antioxidant performance of C. elegans were detected. We also detected the effects on the expression of hsp-16.1, hsp-16.41, hsp-70, sod-3, gst-1, dhs-28 and daf-12 genes at the level of RNA. The results showed that roxarsone had toxic effect on the athletic ability, reproductive system and life span in C. elegans. TDNA percentage, TL and OTM increased gradually according to the increased concentrations of roxarsone. The correlation coefficient of R greater than 0.99 indicated that the concentration-effect relationship was observed in the experimental concentration range. Roxarsone had damage effect on DNA of embryonic cells in C. elegans. With the increase of roxarsone concentration, the activities of SOD and CAT were gradually decreased and the content of malondialdehyde(MDA) was gradually increased. The activities of GSH-Px with 50 ?g/L roxarsone increased comparing to the control group and then gradually decreased. The extremely significant differences were observed at the concentration of 250 and 500 ?g/L. Thus, roxarsone had damage effect on antioxidant performance in C. elegans. Treatment with roxarsone resulted in increases of hsp-16.1, hsp-16.41 and hsp-70 m RNA expressions, decreases of sod-3, gst-1 and daf-12 m RNA expressions, and indistinctive changes of dhs-28 m RNA expressions. Thus, roxarsone had the effect of oxidative stress, cytotoxicity and developmental toxicity on C. elegans.This study discussed the ecotoxicity of roxarsone to soil nematode and C. elegans; Roxarsone could affect the ecological diversity of soil nematodes and cause a variety of toxic damage in C. elegans. These data help to provide an experimental basis for the study of ecological toxicology research, genetic toxicity, mechanism of toxicity, oxidative stress of organoarsenical additives and so on. |
PDF Full Text Request