Physiological and biochemical characteristics of polar cod (Boreogadus saida) from Kongsfjorden

Seasonality of biomarker baseline levels were studied in polar cod (Boreogadus saida), caught in Kongsfjorden, Svalbard, in April, July, September and December, 2006-2007. Physiological parameters (condition factor, gonado- and hepato-somatic indexes, energy reserves, potential metabolic activity and antifreeze activity) in polar cod were used to interpret the seasonality of potential biomarkers. The highest levels of ethoxyresorufin-O-deethylase (EROD) activity occurred concomitantly with the highest potential metabolic activity in July due to e.g. intense feeding. During pre-spawning, EROD showed significant inhibition and gender differences. Hence, its potential use in environmental monitoring should imply gender differentiation at least during this period. Glutathione S-transferase and catalase activities were stable from April to September, but changed in December suggesting a link to low biological activity. Knowledge of the biomarker baseline levels and their seasonal trends in polar cod is essential for a trustworthy interpretation of forthcoming toxicity data and environmental monitoring in the Arctic.

本研究针对2006-2007年4月、7月、9月及12月在斯瓦尔巴群岛（Svalbard）孔斯峡湾（Kongsfjorden）采集的北极鳕（polar cod，Boreogadus saida）的生物标志物基线水平季节变化特征展开研究。研究以北极鳕的多项生理参数为分析基础，包括肥满度、性腺指数、肝体指数、能量储备、潜在代谢活性及抗冻活性，以此解析潜在生物标志物的季节变化规律。乙氧基试卤灵-O-脱乙基酶（ethoxyresorufin-O-deethylase，EROD）活性峰值与7月潜在代谢活性峰值同时出现，该现象或与该时段北极鳕的高强度摄食行为相关。在产卵前期，EROD活性呈现显著抑制特征，且存在明显的性别差异；因此，若将该酶应用于环境监测，至少需在该阶段对样本进行性别区分。谷胱甘肽S-转移酶（glutathione S-transferase）与过氧化氢酶（catalase）的活性在4月至9月间保持稳定，但在12月发生显著变化，提示其活性变化与生物活性降低存在关联。掌握北极鳕的生物标志物基线水平及其季节变化规律，对于可靠解读北极地区未来的毒性测试数据与环境监测结果具有重要意义。