Institute for Environment and Resources, 142 To Hien Thanh Street, District 10, Ho Chi Minh City, Vietnam.
Toxicon. 2010 Jun 15;55(7):1244-54. doi: 10.1016/j.toxicon.2010.01.014. Epub 2010 Feb 2.
The zooplankton grazer Daphnia magna endures living in water bodies up to moderate densities of cyanobacteria, such as Microcystis spp., known for producing toxic secondary metabolites. Although daphnids are affected via decreased food filtering, inhibition of digestive proteases and lethality, development of tolerance against cyanobacterial toxins has also been observed. Aim of our study was to investigate in detail chronic effects of cyanobacterial toxins, with emphasis on microcystin, on D. magna. The animals were exposed chronically for two generations to either microcystin-LR in 5 or 50 microg L(-1), or to cyanobacterial crude extract containing the same amount of total microcystin, starting at neonate stadium. Survival, growth, maturation and fecundity were observed for the first generation during two months. In the offspring survival, maturation, and growth were followed for the first week. Low concentration of microcystin-LR slightly affected the growth and reproduction of parent daphnids. Survivorship decreased during chronic exposure with increasing microcystin concentration. Age to maturity of the offspring increased and their survival decreased after parent generation was exposed to the toxin, even if the offspring were raised in control medium. Besides, cessation of the eggs/embryos was observed and malformation of neonates caused by cyanobacterial toxins was firstly recorded.
大型溞这种浮游动物能在水体内忍受中等密度的蓝藻，如微囊藻属，这些蓝藻以产生有毒的次生代谢物而闻名。尽管大型溞的食物过滤能力下降、消化蛋白酶受到抑制以及其活力降低，但也观察到了对蓝藻毒素的耐受性发展。我们的研究目的是详细研究蓝藻毒素，特别是微囊藻毒素，对大型溞的慢性影响。从幼体阶段开始，动物在两代中持续暴露于 5 或 50μg/L 的微囊藻-LR 或含有相同总量微囊藻毒素的蓝藻粗提取物中。在两个月内观察第一代的存活、生长、成熟和繁殖情况。在第一代的后代中，观察了第一周的存活、成熟和生长情况。低浓度的微囊藻-LR 对亲代大型溞的生长和繁殖有轻微影响。随着微囊藻浓度的增加，慢性暴露期间的存活率下降。亲代暴露于毒素后，后代的成熟年龄增加，存活率下降，即使在对照培养基中饲养后代也是如此。此外，还观察到卵/胚胎停止，并且首次记录到由蓝藻毒素引起的幼体畸形。
