Ecotoxicology and Environmental Safety ( IF 6.8 ) Pub Date : 2020-04-03 , DOI: 10.1016/j.ecoenv.2020.110540 Jieming Li 1 , Jiaqi Hu 1 , Linrong Cao 1 , Yue Yuan 1
By testing time-dependent IC50 of luteolin against Microcystis growth, this study revealed 6.5 mg/L as nearly IC50 value during prolonged stress until day 14, and explored chlorophyll-a (CLA) and phycobiliproteins (PBPs) contents, antioxidant responses and microcystin (MC)-production/-release dynamics at rising luteolin doses (0.5~2-fold IC50). Growth inhibition ratio (GIR) generally rose at rising luteolin dose, while at each dose GIR firstly increased and then leveled off or dropped. In early stage, CLA, allophycocyanin (APC), phycoerythrin (PE) and glutathione (GSH) contents, and superoxide dismutase (SOD) and catalase (CAT) activities, were increasingly stimulated at rising luteolin dose to enhance energy yield and antioxidant defense, but Microcystis was damaged more severely at rising dose, due to stress-repair imbalance. Such more severe damage in early stage, coupled with stronger PBPs-inhibition in mid-late stage, at rising dose could jointly account for rising GIR at rising dose. The CAT/GSH-stimulation persisting until late stage could alleviate cell damage in late stage, which explained for why GIR no longer increased in late stage at each luteolin dose. Besides, more MCs were produced and retained in cell to exert protective roles against luteolin-stress in early stage, but intracellular MCs decreased following inhibited MC-production by prolonged stress to decrease cell protectant. Extracellular MCs detection showed that less MCs amount existed in water phase than control along luteolin-stress, implying luteolin as eco-friendly algaecide with promising potential to remove MPM blooms and MC-risks. This is the first study to reveal the effect of various luteolin doses on MC-production/release and PBP-synthesis dynamics of Microcystis during prolonged stress. The findings shed novel views in anti-algal mechanisms of luteolin, and provided direct evidence for luteolin applied as safe agent to remediate Microcystis-dominant blooms.
中文翻译:
暴露于不同木犀草素剂量的铜绿微囊藻的生长,生理反应和微囊藻素生产/释放动力学。
通过测试木犀草素对微囊藻生长的时间依赖性IC 50值,该研究揭示了在长期胁迫直至第14天时6.5 mg / L接近IC 50值,并探讨了叶绿素a(CLA)和藻胆蛋白(PBPs)含量,抗氧化反应和木犀草素剂量增加时微囊藻毒素(MC)的生产/释放动力学(IC 50的0.5〜2倍))。生长抑制比(GIR)通常在木犀草素剂量增加时上升,而在每剂剂量时,GIR先增加然后稳定或下降。在早期阶段,随着木犀草素剂量的增加,CLA,别藻蓝蛋白(APC),藻红蛋白(PE)和谷胱甘肽(GSH)含量以及超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性受到越来越多的刺激,以增强能量产量和抗氧化防御能力,但微囊藻由于压力修复不平衡,剂量增加时会受到更严重的损害。早期这种更严重的损害,再加上剂量增加时中后期对PBPs的抑制作用增强,可以共同解释剂量增加时GIR升高。持续进行CAT / GSH刺激直至晚期可以减轻晚期细胞损伤,这解释了为什么在每次木犀草素剂量下GIR在晚期不再增加。此外,更多的MCs产生并保留在细胞中,从而在早期对木犀草素应激起保护作用,但细胞内MCs受到长期应激以减少细胞保护剂而抑制MC-产生后减少。细胞外MCs检测表明,沿木犀草素胁迫,水相中MCs的含量比对照少,这表明木犀草素是一种环保的除藻剂,具有消除MPM绽放和MC风险的潜力。这是第一个揭示各种木犀草素剂量对小鼠MC产生/释放和PBP合成动力学影响的研究。长期压力下微囊藻。该发现为木犀草素的抗藻机理提供了新颖的见解,并为木犀草素作为安全剂修复微囊藻显性开花提供了直接证据。