Comparison in copper accumulation and physiological responses of Gracilaria lemaneiformis and G. lichenoides (Rhodophyceae)

Heavy metal pollution has become a worldwide problem in aquaculture. We studied copper (Cu2+ ) accumulation and physiological responses of two red algae Gracilaria lemaneiformis and Gracilaria lichenoides from China under Cu2+ exposure of 0-500 μg/L in concentration. Compared with G. lemaneiformis, G. lichenoides was more capable in accumulating Cu2+ , specifically, more Cu2+ on extracellular side (cell wall) than on intracellular side (cytoplasm) and in cell organelles (especially chloroplast, cell nucleus, mitochondria, and ribosome). In addition, G. lichenoides contained more insoluble polysaccharide in cell wall, which might promote the extracellular Cu2+ -binding as an efficient barrier against metal toxicity. Conversely, G. lemaneiformis was more vulnerable than G. lichenoides to Cu 2+ toxin for decreases in growth, pigment (chlorophyll a, chlorophyll b, phycobiliprotein, and β-carotene) content, and photosynthetic activity. Moreover, more serious oxidative damages in G. lemaneiformis than in G. lichenoides, in accumulation of reactive oxidative species and malondialdehyde, and in electrolyte leakage, because of lower antioxidant enzyme (superoxide dismutase and glutathione reductase) activities. Therefore, G. lichenoides was less susceptible to Cu2+ stress than G. lemaneiformis.     

菊花江蓠(Gracilaria lichenoides)对N、P吸收效应及其细胞超微结构变化

通过设置5个N/P浓度梯度和3个N浓度下的4个N:P梯度,进行了江蓠对N、P的短期(O-4h)和长期(第14天)吸收速率(SNUR和LNUR)以及短期和长期吸收效率(SNUE和LNUE)的研究,同时观察了5个N/P浓度梯度对江蓠细胞超微结构的影响.结果表明:N∶P比为16∶1时,江蓠对N、P的SNUR和LNUR均最大(P＜0.05); N/P为1200/75和960/60μmol/L浓度时,分别对N和P的SNUR最大,达12.85和0.79μmol/(gDW·h),但此N/P浓度下长期培养的江蓠叶绿体结构存在不同程度的损伤;而N/P浓度480/30μmol/L时,对N和P的LNUR均最大值4.23和0.31 μmol/(gDW·h).江蓠对N、P的SNUE和LNUE在介质N/P 60/3.75μmol/L时为最高,而在1200/75 μmol/L时为最低(P＜0.05).