Mussels are widely used in toxicological experimentation; however, experimental setups are not standardized yet. Although there is evidence of changes in biomarker values during food digestion and depending on the mussel nutritive status, the mode of feeding differs among toxicological experiments. Typically, mussels are fed with different diets in different long-term experiments, while fasting is the most common approach for short-term studies. Consequently, comparisons among experiments and reliable interpretations of biomarker results are often unfeasible. The present investigation aimed at determining the influence of fasting (against feeding with Isochrysis galbana) on biomarkers and their responsiveness in mussels exposed for 96 h to the water accommodated fraction (WAF) of a heavy fuel oil (0%, 6.25%, 12.5% and 25% WAF in sea water). PAH tissue levels in digestive gland and a battery of biomarkers were compared. WAF exposure led to decrease of cytochrome-C-oxidase activity, modulated glutathione-S-transferase activity, augmented lipid peroxidation, inhibited acetyl cholinesterase (AChE) activity, and led to lysosomal enlargement (Vv_LYS and S/V_LYS) and membrane destabilisation, lipofuscin accumulation, and histopathological alterations (Vv_BAS, MLR/MET and CTD ratio) in the digestive gland epithelium; and were integrated as IBR/n (biological response index). Overall, no significant changes were recorded in AChE activity, S/V_LYS and CTD ratio in any experimental treatment, while all the other biomarkers showed significant changes depending on the fasting/feeding condition, the exposure to WAF and/or their interaction. As a result, the integrated biomarker index IBR/n was higher at increasing WAF exposure levels both in fasted and fed mussels albeit the response was more marked in the latter. The response profiles were qualitatively similar between fasted and fed mussels but quantitatively more pronounced in fed mussels, especially upon exposure to the highest concentration (25% WAF). Therefore, it is highly recommended that mussels are also supplied with food during short-term, like during long-term toxicological experiments. This practice would avoid the interference of fasting with biological responses elicited by the tested chemicals and allow for reliable comparison with data obtained in long-term experiments and monitoring programmes.

贻贝在毒理学实验中被广泛使用。但是，实验装置尚未标准化。尽管有证据表明食物消化过程中生物标志物的值发生了变化，并且取决于贻贝的营养状况，但在毒理学实验中进食的方式有所不同。通常，贻贝在不同的长期实验中饲喂不同的饮食，而禁食是短期研究中最常见的方法。因此，实验之间的比较和对生物标志物结果的可靠解释通常是不可行的。本研究旨在确定禁食的影响（反对用等鞭金龟（Isochrysis galbana）喂养）的生物标志物及其在贻贝中暴露于重质燃料油的水份（WAF）96小时（海水中0％，6.25％，12.5％和25％WAF）的反应性。比较了消化腺中的PAH组织水平和一系列生物标志物。WAF暴露导致细胞色素C氧化酶活性降低，谷胱甘肽S转移酶活性降低，脂质过氧化作用增强，乙酰胆碱酯酶（AChE）活性受到抑制，并导致溶酶体增大（Vv _LYS和S / V _LYS）和膜失稳，脂褐素积聚和组织病理学改变（Vv _BAS，MLR / MET和CTD比率）在消化腺上皮中；并整合为IBR / n（生物反应指数）。总体而言，AChE活性，S / V _LYS未见明显变化。和CTD比率在任何实验处理中，而所有其他生物标记物均显示出显着变化，具体取决于禁食/喂养条件，WAF暴露和/或其相互作用。结果，在禁食和进食的贻贝中，增加的WAF暴露水平，综合生物标记指数IBR / n较高，尽管后者的反应更为明显。在禁食贻贝和进食贻贝之间，响应曲线在质量上相似，但在进食贻贝中在定量上更为明显，特别是在暴露于最高浓度（25％WAF）的情况下。因此，强烈建议在短期内（例如在长期毒理学实验期间）也向贻贝提供食物。