微囊藻毒素缺氧/厌氧降解产物Adda对秀丽线虫的毒性

微囊藻毒素(MCs)在缺氧/厌氧条件下可以被湖泊沉积物中的土著微生物降解,产生并积累一种降解产物Adda。为了揭示该降解过程的环境安全性,以秀丽线虫(Caenorhabditis elegans)作为模式生物研究了MCs缺氧/厌氧降解产物Adda的毒性。结果表明,低浓度Adda(≤0.05μmol·L-1)暴露对秀丽线虫各项指标均无显著影响,而0.1μmol·L-1的Adda可显著降低线虫的头部和身体摆动频率,说明Adda对线虫运动能力影响较大。当Adda暴露浓度达到0.5μmol·L-1时,可显著影响线虫的寿命、发育、运动能力和生殖能力,但是对畸形率没有显著影响。这些结果说明,Adda的毒性远小于MCLR,因此缺氧/厌氧降解可以有效降低MCLR的毒性。但是考虑到高浓度Adda具有一定毒性,如果Adda大量积累仍可能造成一定的生态影响。

Toxicities of Adda Produced During Microcystin Anoxic/Anaerobic Degradation to Caenorhabditis elegans

Recent studies have shown that micocystins(MCs)can be degraded by indigenous bacteria from lake sediments under anoxic/ anaerobic conditions. Unlike aerobic MCs degradation, in which MCs are completely decomposed, anoxic/anaerobic degradation can produce and accumulate one product Adda. Up to now, however, little is known about the toxicities of this product. To assess the safety of anoxic/ anaerobic degradation of MCs, the toxicities of Adda were investigated using Caenorhabditis elegans(C. elegans)as the animal model. Our results showed that exposure to low dose Adda(not more than 0.05 μmol·L-1)had no negative effect on C. elegans. Exposure to Adda of 0.1 μmol·L-1 could lead to significant defects of head and body locomotion, whereas no negative effect was observed for other functions at the same dosage, suggesting that locomotion ability of C. elegans was more susceptible to Adda than other tested functions. All tested functions except for the rate of vulva abnormality of C. elegans were significantly negatively affected when exposed to Adda of 0.5 μmol·L-1. These re- sults suggest that Adda is far less toxic than MCLR and biodegradation under anoxic/anaerobic conditions can detoxify MCs efficiently. How- ever, the high concentration of Adda may still pose new risks to ecosystem if it accumulates in natural environment during MCs anoxic/anaer- obic degradation.