Effects of the organophosphate insecticide azinphos-methyl on the reproduction and cholinesterase activity of Biomphalaria glabrata

Azinphos-methyl is an organophosphate insecticide used for pest control on a number of food crops in many parts of the world. The snail Biomphalaria glabrata is a freshwater gastropod widely distributed in South America, Central America and Africa. The aim of the present work was to investigate whether azinphos-methyl causes alterations in the reproduction of B. glabrata. To this end, gastropod pigmented specimens were exposed to various concentrations of the insecticide (0.021, 0.5, 2.5, and 5 mg L⁻¹) for either 2 or 14 d. Along 14 d, several reproduction parameters and cholinesterase (ChE) activity were evaluated. In each group, the number of egg masses, the number of eggs per mass, the number of hatchings, the time to hatching, and the survival of the offspring after one month of treatment was evaluated. The results showed that, depending on the concentration and time of exposure, azinphos-methyl induced alterations in the reproduction of B. glabrata. These alterations were mainly represented by a decrease in the number of egg masses, and, in some cases, by a lower number or even the total absence of hatchings. Thus, the gastropods exposed to 2.5 and 5 mg L⁻¹ of azinphos-methyl for 14 d showed ChE inhibitions higher than 35% along time and completely lost their ability to reproduce. On the other hand, exposure to high acute concentrations or exposure to low concentrations for 14 d resulted in ChE inhibition equal to or lower than 35% between 7 and 14 d of treatment and similar alterations in reproduction. These were represented by a decrease in the number of egg masses. At low pestice levels, the number of egg masses and the number of offspring resulted to be more sensitive biomarkers than ChE inhibition. It is concluded that the insecticide azinphos-methyl can cause a decline in the reproductive performance of B. glabrata.     

胆碱脂酶作为水生生物的生物标志物研究进展

应用水生生物胆碱脂酶作为生物标志物对水环境中有机磷和氨基甲酸盐杀虫剂的暴露和效应进行评价日益受到重视。它作为一种快捷有效的监测工具，将会在环境监测中得到越来越广泛深入的应用。本文介绍了该生物标志物的作用原理、应用方向，以及检测酶活性抑制的研究方法，并对它的影响因子进行分析。最后阐述了发展前景。     

铜、镉、敌敌畏和甲胺磷对南美白对虾的亚急性毒性作用

在恒温和充气条件下,研究了重金属(铜、镉)和有机磷农药(敌敌畏、甲胺磷)对南美白对虾的亚急性毒性作用及对虾体胆碱酯酶的影响.结果表明:南美白对虾幼虾在各浓度重金属(铜、镉)和有机磷农药(敌敌畏、甲胺磷)试液中经过60d的亚急性中毒试验,除铜在低浓度促进生长外,其他各组体长、体重及蜕皮次数均小于对照组,且随毒物浓度的增加而逐渐降低;有机磷农药对南美白对虾体内胆碱酯酶具有显著影响,虾体内胆碱酯酶含量随水体中有机磷农药浓度的升高而显著降低;重金属对胆碱酯酶也有一定影响,胆碱酯酶随重金属离子浓度升高也有逐渐降低的趋势,但重金属对胆碱酯酶的影响效果没有有机磷农药显著.     

Hormetic response of cholinesterase from Daphnia magna in chronic exposure to triazophos and chlorpyrifos

In vivo activity of cholinesterase (ChE) in Daphnia magna was measured at di erent time points during 21-day exposure to triazophos and chlorpyrifos ranging from 0.05 to 2.50 g/L and 0.01 to 2.00 g/L, respectively. For exposure to triazophos, ChE was induced up to 176.5% at 1.5 g/L and day 10 when measured by acetylthiocholine (ATCh), whereas it was induced up to 174.2% at 0.5 g/L and day 10 when measured by butyrylthiocholine (BTCh). For exposure to chlorpyrifos, ChE was induced up to 134.0% and 160.5% when measured by ATCh and BTCh, respectively, with both maximal inductions detected at 0.1 g/L and day 8. Obvious induction in terms of ChE activity was also detected in daphnia removed from exposures 24 hr after their birth and kept in a recovery culture for 21 days. Results indicated that the enzyme displayed symptoms of hormesis, a characteristic featured by conversion from low-dose stimulation to high-dose inhibition. In spite of that, no promotion in terms of reproduction rate and body size was detected at any tested concentrations regardless of whether the daphnia were collected at end of the 21-day exposure or at end of a 21-day recovery culture. This suggested that induction of ChE caused by anticholinesterases had nothing to do with the prosperity of the daphnia population.