Esteves S M, Almeida S F P, Gonçalves S, Rimet F, Bouchez A, Figueira E
Department of Biology, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
CESAM, Centre for Environment and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
Ecotoxicology. 2018 Sep;27(7):860-870. doi: 10.1007/s10646-018-1953-1. Epub 2018 Jun 16.
Organic contaminants, and herbicides in particular, represent a risk for aquatic ecosystems. The primary target of herbicides are producers, the base of food webs, but frequently they end up far from the application point affecting non-target species. Its presence can work as sub-lethal stimulus, which sort the genetic and phenotypic differences within a species. Intraspecific variation allows adaptation to changes in the environment but also to new niches due to variations in species' sensitivity and biochemical response to a certain chemical. A better understanding of these variations can lead to the development of improved strategies for ecosystem protection. This research aimed to compare a sensitive and a tolerant strain of the freshwater diatom Nitzschia palea to atrazine. Strains were exposed to three concentrations within their tolerance range, during 96 h. The activity of the antioxidant enzymes superoxide dismutase, catalase, glutathione-S-transferases and glutathione peroxidases was determined. In addition, chlorophylls a and c, carotenoids, reduced glutathione, proteins and lipid peroxidation were quantified. Both strains displayed different strategies to deal with atrazine toxicity: while the sensitive strain decreased the oxidative stress, increasing the activity of antioxidant enzymes such as superoxide dismutase, the tolerant strain invested in conjugation pathways and carotenoids' maintenance.
有机污染物，尤其是除草剂，对水生生态系统构成风险。除草剂的主要作用目标是生产者，即食物网的基础，但它们常常会扩散到远离施用点的地方，影响非目标物种。其存在可能作为亚致死刺激，引发物种内部的遗传和表型差异。种内变异不仅能使物种适应环境变化，还能因物种对特定化学物质的敏感性和生化反应的差异而适应新的生态位。更好地理解这些变异有助于制定更完善的生态系统保护策略。本研究旨在比较淡水硅藻纤细菱形藻的敏感株和耐受株对阿特拉津的反应。将藻株在其耐受范围内的三种浓度下暴露96小时。测定了抗氧化酶超氧化物歧化酶、过氧化氢酶、谷胱甘肽-S-转移酶和谷胱甘肽过氧化物酶的活性。此外，还对叶绿素a和c、类胡萝卜素、还原型谷胱甘肽、蛋白质和脂质过氧化进行了定量分析。两种藻株应对阿特拉津毒性的策略不同：敏感株通过增加超氧化物歧化酶等抗氧化酶的活性来降低氧化应激，而耐受株则通过共轭途径和维持类胡萝卜素来应对。
