PVC微塑料对大型溞繁殖及应激与能量相关基因表达的影响

Effect of PVC microplastic on reproduction and energy-related gene expression of Daphnia magna

近年来,微塑料污染已成为海洋和淡水生态环境关注的热点问题.然而,目前有关微塑料对淡水生物影响的报道仍然较少.试验选择淡水模式动物大型溞作为受试生物,以2μm聚氯乙烯微粒(PVC)作为研究对象,探讨了PVC微塑料对大型溞繁殖和基因表达的影响.急性毒性试验表明,PVC对大型溞的48 h LC50为20.5 mg·L^(-1).21 d慢性毒性试验发现,随着PVC浓度的增加,产第一胎时间显著延迟,第一胎产幼溞数明显下降;总胎数在2.56mg·L^(-1)和5.125 mg·L^(-1) PVC处理组无明显差异,而10.25 mg·L^(-1)处理组显著增加,但所有处理组产幼溞总数与对照组相比均显著下降.同时,PVC暴露大型溞48 h后显著上调超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、α-酯酶(EST)、热休克蛋白70(HSP70)、精氨酸激酶(AK)和血红蛋白(DHB)基因表达.试验结果表明,PVC微塑料能干扰大型溞体内基因表达,长期暴露可显著降低大型溞繁殖量,水体中PVC微塑料的长期存在将对水生态系统产生危害.

Recently, microplastics pollution has been met a great interest regarding to marine and freshwater ecological environments. However, its effects on freshwater organisms are still not fully elucidated. In this study, impact of 2 μm polyvinyl chloride particles(PVC) on reproduction and energy-related gene expressions of Daphnia magna was investigated. The LC50 after 48 h of exposure to PVC was 20.5 mg·L^(-1). With the increase of concentration, PVC significantly delayed the days to first brood and reduced the number of first-brood offspring. No significant difference was observed in the total number of broods after exposed to 2.56 and 5.125 mg · L^(-1) groups, whereas, 10.25 mg · L^(-1) PVC significantly increased the total number of broods of D. magna. Furthermor, the total number of offspring was decreased significantly in all treatment groups compared with the control group. Moreover, PVC significantly increased the transcriptional expressions of superoxide dismutase(SOD), catalase(CAT), α-esterase(EST), heat shock protein 70(HSP70), arginine kinase(AK) and hemoglobin(DHB) in D. magna after 48 h of exposure notably at 10.25 mg·L^(-1). Finally, these results can reflect to how harm the microplastics can cause either to gene expressions or reproduction of other organisms in the aquatic ecosystem.