Copper (Cu) is one of the most harmful contaminants in fresh-water systems. Fish larvae such as sacfry are particularly vulnerable to metals such as copper (Cu) due to a less-developed excretory organ system and permeable skin that can absorb metals directly from the water. However, the sublethal effects of metals on this life stage are not well understood. This study assessed the sublethal toxicity of Cu on purple-spotted gudgeon sacfry (PSG, Mogurnda adspersa). For this purpose, 96 h Cu toxicity bioassays were performed and toxic effects of Cu on PSG were measured at different levels of biological organization, from the individual (loss of equilibrium, wet weight), to tissue (chemical changes in retinal tissue composition) and molecular responses (whole body amino acid (AA) profiles). The EC₁₀ and EC₅₀ (ECx: effect concentration that affected X% of test organisms) were found to be 12 (9 – 15) µg Cu L⁻¹ and 22 (19 – 24) µg Cu L⁻¹, respectively. Copper stress caused a decrease in total amino acid content and changed the AA profile of PSG compared to the controls. Proton-induced X-ray emission (PIXE) mapping techniques showed accumulation of Cu in the retinal tissues disturbing the distribution of other elements such as zinc, sulfur, phosphorus and potassium. Fourier-transform infrared (FTIR) microspectroscopy of control and Cu treated eye tissues revealed a change in protein secondary structure in retinal tissues in response to Cu accumulation, as well as decreased levels of the molecular retinal, consistent with the degradation of rhodopsin, a key protein in the visual sensory system. This is the first study to demonstrate the multi-level responses of PSG arising from exposure to environmentally realistic Cu concentrations and suggests that AA profiling can serve as a useful tool to assess the impacts of metals on fresh-water organisms.

铜 (Cu) 是淡水系统中最有害的污染物之一。由于不发达的排泄器官系统和可直接从水中吸收金属的可渗透皮肤，诸如 sacfry 之类的鱼类幼虫特别容易受到铜 (Cu) 等金属的影响。然而，金属在这个生命阶段的亚致死效应尚不清楚。本研究评估了 Cu 对紫斑海鱼 (PSG, Mogurnda adspersa ) 的亚致死毒性。为此，进行了 96 小时铜毒性生物测定，并在不同水平的生物组织测量了铜对 PSG 的毒性作用，从个体（失去平衡、湿重）到组织（视网膜组织成分的化学变化）和分子反应（全身氨基酸（AA）谱）。欧共体₁₀和 EC ₅₀（ECx：影响 X% 测试生物体的效应浓度）被发现为 12 (9 – 15) µg Cu L ^-1和 22 (19 – 24) µg Cu L ^-1， 分别。与对照相比，铜胁迫导致总氨基酸含量降低并改变了 PSG 的 AA 谱。质子诱导的 X 射线发射 (PIXE) 映射技术显示，Cu 在视网膜组织中的积累干扰了锌、硫、磷和钾等其他元素的分布。对照和 Cu 处理的眼组织的傅里叶变换红外 (FTIR) 显微光谱揭示了视网膜组织中蛋白质二级结构响应于 Cu 积累的变化，以及分子视网膜水平的降低，这与视紫红质的降解一致，这是一个关键视觉感觉系统中的蛋白质。