Algal species Raphidocelis subcapitata and Chlorella vulgaris are commonly used to test the chemicals with an antibacterial mode of action during marketing authorization process. However, significant differences in the sensitivity toward antibiotic exposure have been reported. The selection of an inappropriate test species would thus underestimate the environmental hazard of target chemicals and pose a potential threat to the ecosystem. Since oxidative stress is a crucial factor determining the inhibition of algal growth, an investigation on oxidative stress and antioxidant defense mechanisms in these two species was performed to explore its roles in species sensitivity. Here, roxithromycin (ROX), a macrolide antibiotic extensively used to treat respiratory, urinary and soft tissue infections, was used for testing. After 7 days exposure to ROX at the low (0.01 mg L-1) and high (0.09 mg L-1) concentrations, R. subcapitata was inhibited while the growth of C. vulgaris was stimulated. We investigated the roles of oxidative stress in algae by measuring the oxidative stress biomarkers (MDA), non-enzymatic antioxidants (GSH), and antioxidant enzymes (SOD, CAT, GP, GST). The results suggested that when the growth of algae is inhibited, MDA content as well as activities of oxidative stress enzymes would increase, and thus, activating the antioxidant system. On the contrary, it was inferred that when the growth is stimulated, MDA content and oxidative stress enzymes activities would decrease.

中文翻译：

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氧化应激涉及两种暴露于罗红霉素的藻类的敏感性。

在上市授权过程中，藻种拉菲多氏藻和小球藻通常用于测试具有抗菌作用模式的化学物质。然而，已经报道了对抗生素暴露的敏感性的显着差异。因此，选择不适当的测试物种会低估目标化学品的环境危害，并对生态系统构成潜在威胁。由于氧化应激是决定藻类生长抑制的关键因素，因此对这两个物种的氧化应激和抗氧化防御机制进行了研究，以探讨其在物种敏感性中的作用。在这里，罗红霉素（ROX）是一种大环内酯类抗生素，广泛用于治疗呼吸道，泌尿系统和软组织感染，用于测试。在低浓度（0.01 mg L-1）和高浓度（0.09 mg L-1）的ROX中暴露7天后，亚皮下衣原体被抑制，而寻常菜的生长受到刺激。我们通过测量氧化应激生物标志物（MDA），非酶抗氧化剂（GSH）和抗氧化酶（SOD，CAT，GP，GST）来研究氧化应激在藻类中的作用。结果表明，当藻类的生长受到抑制时，MDA含量以及氧化应激酶的活性将增加，从而激活抗氧化剂系统。相反，推断出当刺激生长时，MDA含量和氧化应激酶活性将降低。我们通过测量氧化应激生物标志物（MDA），非酶抗氧化剂（GSH）和抗氧化酶（SOD，CAT，GP，GST）来研究氧化应激在藻类中的作用。结果表明，当藻类的生长受到抑制时，MDA含量以及氧化应激酶的活性将增加，从而激活抗氧化剂系统。相反，推断出当刺激生长时，MDA含量和氧化应激酶活性将降低。我们通过测量氧化应激生物标志物（MDA），非酶抗氧化剂（GSH）和抗氧化酶（SOD，CAT，GP，GST）来研究藻类中氧化应激的作用。结果表明，当藻类的生长受到抑制时，MDA含量以及氧化应激酶的活性将增加，从而激活抗氧化剂系统。相反，推断出当刺激生长时，MDA含量和氧化应激酶活性将降低。