罗红霉素对大型溞生殖生长及抗氧化系统的影响

Effects of Roxithromycin on Reproduction,Growth,and Anti-oxidation System of Daphnia magna

罗红霉素(ROX)在水环境中广泛赋存,并产生一定的生态毒理效应.为了进一步认知ROX对水生生物的负面影响,以大型溞为模式生物研究了ROX在生殖、生长及抗氧化系统方面的急慢性毒理效应.结果发现ROX对大型溞的急性毒性等级为Ⅲ级(48h-LC_(50)为60.26 mg·L^(-1),96h-LC_(50)为39.81 mg·L^(-1)).0.5μg·L^(-1)和50μg·L^(-1)的ROX均显著增加了大型溞的产卵胎次,提高了大型溞的产卵总量和每胎产卵量.暴露初期ROX改变了大型溞的性成熟时间,大型溞通过调节产卵胎数和单胎产卵数量,弥补ROX造成的环境胁迫,50μg·L^(-1)ROX显著提升了大型溞的内禀增长率.ROX暴露组中大型溞均出现了体长变短、心率失调和游泳活性抑制现象.50μg·L^(-1)ROX对POD(过氧化物酶)、CAT(过氧化氢酶)和GSH-Px(谷胱甘肽)的抑制率接近50%,对MDA(丙二醛)的诱导甚至超过100%,造成机体内活性氧蓄积,损伤细胞膜.大型溞通过上调per06表达,增强体内免疫应答,但gst和gst-theta表达受到抑制下调,解毒作用减弱,ROX抑制了大型溞jhe、ecra、ecrb、rxr、vg1、vg2和vit-2基因表达,致使保幼激素和甲状腺激素分泌紊乱和卵黄蛋白合成受阻,影响其生长发育和种群稳定.本结果为水环境中ROX对水生生物的生殖和生长及在蛋白水平和基因水平的响应提供了借鉴.

Roxithromycin(ROX)is widespread in the water environment and has been reported to have ecotoxicological effects on aquatic organisms.To improve our understanding of these effects,we selected Daphnia magna as a test organism to study acute and chronic ROX toxicity on reproduction,growth,and antioxidant systems.The acute ROX toxicity was low,with 48 h-LC_(50)and 96h-LC_(50)ROX values of 60.26 mg·L^(-1)and 39.81 mg·L^(-1),respectively.Furthermore,ROX concentrations of 0.5μg·L^(-1)and 50μg·L^(-1)significantly increased the frequency of egg laying,total number of eggs,and number of eggs per fetus.In the early exposure stages,ROX altered the sexual maturation time of Daphnia magna,affecting the frequency of egg laying and the number of eggs per fetus to cope with environmental stress.The intrinsic growth rate was also significantly increased by 50μg·L^(-1)ROX.In both treatment groups,Daphnia magna had a shorter body length,abnormal heart rate,and inhibited swimming activity.Moreover,50μg·L^(-1)ROX inhibited the activities of POD,CAT,and GSH-Px by approximately 50%and induced MDA by more than 100%,resulting in the accumulation of reactive oxygen species in the body,which could potentially damage the cell membrane.In the 50μg·L^(-1)ROX treatment,per06 was up-regulated,enhancing the immune response of Daphnia magna.In contrast.gst and gst-theta were downregulated,suggesting that ROX could weaken the detoxification effect of Daphnia magna.jhe,ecra,ecrb,rxr,vg1,vg2,and vit-2were also down-regulated.ROX affected the secretion of juvenile and thyroid hormones,inhibiting the synthesis of vitellogenin.Finally,ROX also affected the growth and disturbed the population stability of Daphnia magna.This study provides a reference for the effects of ROX on the reproduction and growth of aquatic organisms and their responses at protein and gene levels.