摘要:
六溴环十二烷(hexabromocyclododecane,HBCDs)是一种添加型阻燃剂,在环境中广泛存在。由于具有持久性、生物蓄积性和毒性等特征,HBCD很可能在水生生物体内富集并对其生长发育产生影响。将斑马鱼胚胎暴露于不同浓度的HBCD (0.1、0.5和1 mg·L-1),通过油红O和阿尔新蓝染色观察幼鱼发育状况,并通过能量代谢及发育相关基因探讨可能的作用机制。结果表明,HBCD暴露影响了幼鱼对卵黄囊内生脂肪的吸收,并对幼鱼躯干骨骼肌、头部软骨和鱼鳍的发育产生损害。进一步研究发现,暴露组幼鱼体内ATP含量降低,ATP合成酶及电子呼吸链中还原性辅酶Ⅰ(NOX)和细胞色素C氧化酶(COX)等的活性显著降低;同时,早期发育相关基因如骨形成蛋白bmp、肌肉决定因子myod以及sox9a和wnt等基因的转录水平均受到显著抑制(P < 0.05)。上述结果表明,HBCD会影响早期发育阶段的斑马鱼对卵黄囊营养物质的吸收,干扰体内能量代谢,导致能量供应不足,并通过bmp-sox9和wnt-myod等信号通路影响软骨组织、鱼鳍和骨骼肌的正常发育。
Abstract:
Hexabromocyclododecane (HBCD) is a widely used flame retardant and ubiquitously distributed in the environment. Characterized as persistent, bioaccumulative and toxic chemicals, HBCD could enrich in fish tissues and cause adverse effects on their early development. Zebrafish embryos (0.5 hpf) were exposed to different HBCD concentrations (0.1, 0.5 and 1 mg·L-1) until 120 hpf. The changes in the development of cartilage, muscle and fin were assessed, and the underlying molecular mechanism was studied. Oil Red O staining test revealed an inhibition of lipid absorption in zebrafish larvae yolk sac; microscopic observations including impaired skull cartilage development, irregular myofiber structure abnormality in fins were found in HBCD exposed larvae. Moreover, the activities of cytochrome c oxidase (COX), nicotinamide adenine dinucleotideoxidoreductases (NOX) and ATP synthetase were inhibited, resulting in decreased ATP contents; meanwhile, the transcripts of bmp, sox9a, wnt and myod were all down-regulated (P < 0.05). In conclusion, exposure to HBCD at early life stages could result in insufficient nutrient yield and transportation, thus disturb the energy metabolism and regulations of signaling pathways such as bmp-sox9a and wnt-myod, and finally affect the normal development of tissues such as cartilage, muscle and fins.
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