Best J H, Pflugmacher S, Wiegand C, Eddy F B, Metcalf J S, Codd G A
Division of Applied and Environmental Biology, School of Life Sciences, University of Dundee, DD1 4HN, Dundee, UK.
Aquat Toxicol. 2002 Oct 30;60(3-4):223-31. doi: 10.1016/s0166-445x(02)00010-3.
Cyanobacteria (blue-green algae) can produce a variety of toxins including hepatotoxins e.g. microcystins, and endotoxins such as lipopolysaccharides (LPS). The combined effects of such toxins on fish are little known. This study examines the activities of microsomal (m) and soluble (s) glutathione S-transferases (GST) from embryos of the zebra fish, Danio rerio at the prim six embryo stage, which had been exposed since fertilisation to LPS from different sources. A further aim was to see how activity was affected by co-exposure to LPS and microcystin-LR (MC-LR). LPS were obtained from Salmonella typhimurium, Escherichia coli, a laboratory culture of Microcystis CYA 43 and natural cyanobacterial blooms of Microcystis and Gloeotrichia. Following in vivo exposure of embryos to each of the LPS preparations, mGST activity was significantly reduced (from 0.50 to between 0.06 and 0.32 nanokatals per milligram (nkat mg(-1)) protein). sGST activity in vivo was significantly reduced (from 1.05 to between 0.19 and 0.22 nkat mg(-1) protein) after exposure of embryos to each of the cyanobacterial LPS preparations, but not in response to S. typhimurium or E. coli LPS. Activities of both m- and sGSTs were reduced after co-exposure to MC-LR and cyanobacterial LPS, but only mGST activity was reduced in the S. typhimurium and E. coli LPS-treated embryos. In vitro preparations of GST from adult and prim six embryo D. rerio showed no significant changes in enzyme activity in response to the LPS preparations with the exception of Gloeotrichia bloom LPS, where mGST was reduced in adult and embryo preparations. The present study represents the first investigations into the effects of cyanobacterial LPS on the phase-II microcystin detoxication mechanism. LPS preparations, whether from axenic cyanobacteria or cyanobacterial blooms, are potentially capable of significantly reducing activity of both the s- and mGSTs, so reducing the capacity of D. rerio to detoxicate microcystins. The results presented here have wide ranging implications for both animal and human health.
蓝藻（蓝绿藻）能产生多种毒素，包括肝毒素，如微囊藻毒素，以及内毒素，如脂多糖（LPS）。此类毒素对鱼类的综合影响鲜为人知。本研究检测了斑马鱼（Danio rerio）原肠胚期胚胎微粒体（m）和可溶性（s）谷胱甘肽S-转移酶（GST）的活性，这些胚胎自受精起就暴露于不同来源的LPS中。另一个目的是观察同时暴露于LPS和微囊藻毒素-LR（MC-LR）时活性如何受到影响。LPS分别取自鼠伤寒沙门氏菌、大肠杆菌、微囊藻CYA 43的实验室培养物以及微囊藻和胶鞘藻的自然蓝藻水华。胚胎在体内暴露于每种LPS制剂后，微粒体GST活性显著降低（从每毫克蛋白质0.50纳卡特降至0.06至0.32纳卡特之间（nkat mg(-1)））。胚胎在体内暴露于每种蓝藻LPS制剂后，可溶性GST活性显著降低（从每毫克蛋白质1.05纳卡特降至0.19至0.22纳卡特之间（nkat mg(-1)）），但对鼠伤寒沙门氏菌或大肠杆菌LPS无反应。同时暴露于MC-LR和蓝藻LPS后，微粒体和可溶性GST的活性均降低，但在经鼠伤寒沙门氏菌和大肠杆菌LPS处理的胚胎中，只有微粒体GST活性降低。来自成年和原肠胚期斑马鱼的GST体外制剂显示，除胶鞘藻水华LPS外，酶活性对LPS制剂无显著变化，在成年和胚胎制剂中，胶鞘藻水华LPS使微粒体GST降低。本研究首次调查了蓝藻LPS对II期微囊藻毒素解毒机制的影响。LPS制剂，无论是来自无菌蓝藻还是蓝藻水华，都有可能显著降低可溶性和微粒体GST的活性，从而降低斑马鱼解毒微囊藻毒素的能力。此处呈现的结果对动物和人类健康都有广泛影响。
