Water Pollution Ecology Laboratory, College of Life Sciences, Wuhan University, Wuhan 430072, PR China; National Field Station of Freshwater Ecosystem in Liangzi Lake, College of Life Sciences, Wuhan University, Wuhan 430072, PR China.
Water Pollution Ecology Laboratory, College of Life Sciences, Wuhan University, Wuhan 430072, PR China.
Ecotoxicol Environ Saf. 2022 Jul 1;239:113690. doi: 10.1016/j.ecoenv.2022.113690. Epub 2022 May 26.
Ciprofloxacin is ubiquitous and poses a potential threat to aquatic ecosystems. However, the comprehensive effect of prolonged ciprofloxacin exposure on the submerged clonal plant Vallisneria natans (Lour.) Hara remains unknown. Growth and physiological responses in V. natans exposed to ciprofloxacin at concentrations of 0, 0.05, 0.25, 1.25, 2.5, 5 and 10 mg/L were repeatedly evaluated on Days 7, 14, 28, 42 and 56. V. natans maintained good growth properties under 0.05-0.25 mg/L ciprofloxacin treatments, while the inhibition effect on plant growth induced by higher-concentration treatments increased over time. The IC50 values of ciprofloxacin for growth endpoints ranged from 1.6 mg/L to 5.3 mg/L and displayed time-dependent decreases. Pigment contents were significantly stimulated by ciprofloxacin on Day 7 but decreased to varying degrees as the exposure time was extended. Soluble protein and hydrogen peroxide content rose significantly over the first 14 days of treatment with 0.25-10 mg/L ciprofloxacin but decreased under 1.25-10 mg/L ciprofloxacin treatments since Day 28. Antioxidants including superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase and proline functioned well in mitigating oxidative stress under different ciprofloxacin concentrations, lowering the comprehensive toxic effects of ciprofloxacin on V. natans during the period from Day 14 to Day 42, as evidenced by decreased IBR (integrated biomarker response) values. However, the toxic pressure of ciprofloxacin on V. natans peaked on Day 56. These findings suggest that exposure time can influence the responses of V. natans exposed to ciprofloxacin and that IBR can be employed to evaluate the integrated impacts of prolonged ciprofloxacin contamination in aquatic settings.
环丙沙星无处不在，对水生生态系统构成潜在威胁。然而，长期暴露于环丙沙星对沉水克隆植物苦草（Vallisneria natans（Lour.）Hara）的综合影响尚不清楚。在第 7、14、28、42 和 56 天，反复评估了浓度为 0、0.05、0.25、1.25、2.5、5 和 10mg/L 的环丙沙星暴露下苦草的生长和生理反应。在 0.05-0.25mg/L 环丙沙星处理下，苦草保持良好的生长特性，而高浓度处理对植物生长的抑制作用随时间的推移而增加。环丙沙星对生长终点的 IC50 值范围为 1.6-5.3mg/L，呈时间依赖性降低。在第 7 天，环丙沙星显著刺激了色素含量，但随着暴露时间的延长，色素含量逐渐降低。在 0.25-10mg/L 环丙沙星处理的前 14 天，可溶性蛋白和过氧化氢含量显著升高，但在第 28 天以后，1.25-10mg/L 环丙沙星处理下的含量下降。在不同浓度的环丙沙星下，超氧化物歧化酶、过氧化氢酶、愈创木酚过氧化物酶、抗坏血酸过氧化物酶和脯氨酸等抗氧化剂能够很好地发挥作用，减轻氧化应激，从而降低了环丙沙星对苦草在第 14 天至第 42 天期间的综合毒性效应，这一点从 IBR（综合生物标志物响应）值的降低可以看出。然而，在第 56 天，环丙沙星对苦草的毒性压力达到峰值。这些发现表明，暴露时间会影响暴露于环丙沙星的苦草的反应，并且 IBR 可用于评估水生环境中长时间环丙沙星污染的综合影响。
