对羟基苯甲酸丙酯对食蚊鱼(Gambusia affinis)鳃和表皮K^(+)流速的影响

食品、医药和化妆品等行业大量使用含有对羟基苯甲酸丙酯(propylparaben,PrP)的防腐剂导致其广泛分布于河流、空气和土壤等自然环境中。为探究PrP对鱼类的毒性作用,以食蚊鱼(Gambusia affinis)为模式生物,分别开展了急性毒性实验和K^(+)流速检测实验。急性毒性实验中设置8种不同浓度的PrP溶液得到96 h半数致死浓度(96 h-LC_(50))和安全浓度;在K^(+)流速检测实验中利用非损伤微测技术(non-invasive micro-test technology,NMT)分别检测在3种不同浓度(96 h-LC_(50)/10(0.9 mg·L^(-1)),96 h-LC_(50)/5(1.8 mg·L^(-1)),96 h-LC_(50)/2(4.6 mg·L^(-1)))的PrP溶液瞬时暴露和96 h暴露后食蚊鱼表皮和鱼鳃的K^(+)流速变化。急性毒性实验结果表明,PrP的96 h-LC_(50)为9.14 mg·L^(-1),安全浓度为2.85 mg·L^(-1);K^(+)离子流速检测实验结果表明,随着PrP暴露浓度的升高,K^(+)流速波动区间逐渐增大,且与暴露浓度成正相关;PrP瞬时暴露和96 h暴露后鱼鳃细胞均向外排出K^(+),具有剂量效应,K^(+)外排量随着浓度的升高而增大;与之相反,鱼体表皮细胞向内吸收K^(+),K^(+)流速波动区间随着浓度的升高而增大,呈现一定的剂量效应。上述研究结果表明,PrP对鱼体有一定的毒性,会破坏鱼体内钠钾泵的离子转运功能,PrP毒性强度与暴露时间和暴露方式有关,比较实验中鱼体2种组织的细胞,鱼体表皮细胞抵抗PrP损伤的能力更强,鱼鳃细胞对PrP暴露更敏感,鱼鳃细胞K^(+)流速的变化可以有效指示PrP的毒性效应,为进一步研究PrP对鱼类的毒性机制提供依据。

Effect of Water Ammonia Nitrogen Concentration on Survival of Mosquitofish Gambusia affinis

In this study, the relationship of the growth of invasion fish with water eutrophication processes was explored in Yangtze estuary, China. High water ammonia nitrogen concentration produced high effects on the growth and survival of mosquitofish Gambusia affinis. When the ammonia nitrogen was higher than 51.75 mg/l, the fish death rate obviously increased with days, and at the 4th day fish presented the highest mortality, while 23.72 mg/l ammonia nitrogen conditions have been able to ensure fish survival for two days in experiment treatment. Therefore, ammonia nitrogen of Grade V polluted water (national water quality criteria) is just 3 mg/l, and the water can be enough to support fish normal survival. Our results suggest mosquitofish was a suitable pioneer species for restoring polluted water ecology and purify water.