DataSheet_1_Cellular disturbance and thermal stress response in mussels exposed to synthetic and natural microfibers.pdf

Textile microfibers (MFs) have natural (e.g. cotton, wool and silk) or synthetic origin (e.g. polyester and polyamide), and are increasingly documented in the marine environment. Knowledge on their biological effects in marine organisms is still limited, and virtually unexplored is their capability to modulate the responsiveness toward other stressors, including those of emerging relevance under global changes scenario. With such background, the aims of this study were to i) determine the ingestion and biological effects of MFs, discriminating between synthetic and natural ones, and ii) elucidate the possibility that MFs alter the responsiveness toward additional stressors occurring at a later stage, after exposure. Adult mussels Mytilus galloprovincialis were exposed for 14 days to a high but still environmentally realistic concentration of 50 MFs L-1 of either polyester (618 ± 367 µm length, 13 ± 1 µm diameter), polyamide (566 ± 500 µm length, 11 ± 1 µm in diameter) or cotton (412 ± 342 µm length, 16 ± 4 µm diameter). After the exposure, mussels were left for 7 days to recover at control temperature (23°C) or exposed to a heatwave condition (27°C). At the end of each phase (exposure – recovery – heat stress), MFs ingestion-elimination was evaluated, along with a wide panel of biological responses, including neuro-immune and antioxidant systems alterations, lipid metabolism and onset of cellular damages. Results were elaborated through a Weight of Evidence approach to provide synthetic hazard indices based on both the magnitude and toxicological relevance of observed variations. Beside limited differences in retention and elimination of MFs, biological analyses highlighted disturbance of the immune system and demand of protection toward oxidative insult, particularly evident in mussels exposed to synthetic-MFs. Carry-over effects were observed after 7 days of recovery: organisms that had been previously exposed to MFs showed a higher susceptibility of the neuroendocrine-immune system and lipid metabolism to thermal stress compared to un-exposed mussels. Overall, this study provided evidence of direct cellular effects of MFs, emphasizing differences between synthetic and natural ones, and highlighted their capability to modulate organisms’ susceptibility toward additional stressors, as those predicted for future changes in marine ecosystems.

纺织微纤维（MFs）可分为天然来源（如棉花、羊毛与蚕丝）与合成来源（如聚酯、聚酰胺）两类，目前其在海洋环境中的检出率正逐年上升。学界对其在海洋生物体内引发的生物学效应认知仍十分有限，而其对其他胁迫因子的响应调控能力更是几乎未被探索——其中就包括全球变化背景下日益受到关注的各类胁迫因子。基于上述研究背景，本研究的目标分为两点：其一，明确纺织微纤维的摄入情况及其生物学效应，并区分合成来源与天然来源微纤维之间的差异；其二，阐明纺织微纤维是否会在暴露后阶段，改变生物对后续其他胁迫因子的响应能力。本研究将成年紫贻贝（Mytilus galloprovincialis）暴露于浓度为50个MFs·L⁻¹的环境中14天，该浓度虽偏高但仍符合海洋环境实际水平；受试微纤维分别为聚酯（长度618±367 μm，直径13±1 μm）、聚酰胺（长度566±500 μm，直径11±1 μm）与棉花（长度412±342 μm，直径16±4 μm）三类。暴露阶段结束后，将受试贻贝分为两组：一组在对照温度（23℃）下进行7天的恢复培养，另一组则暴露于热浪环境（27℃）中。在每个阶段（暴露、恢复、热胁迫）结束时，分别评估贻贝对纺织微纤维的摄入与清除情况，并检测多组生物学响应指标，包括神经免疫系统与抗氧化系统的变化、脂质代谢异常以及细胞损伤的发生情况。研究采用证据权重法（Weight of Evidence）对实验结果进行整合分析，基于观测到的变化幅度与毒理学相关性，构建综合危害指数。尽管各类微纤维的滞留与清除仅存在细微差异，但生物学分析结果显示，合成来源微纤维暴露组的贻贝免疫系统受到明显干扰，且机体需要对抗氧化损伤，该现象在合成微纤维暴露组中尤为显著。在7天恢复培养后，研究观察到遗留效应：与未暴露过纺织微纤维的贻贝相比，此前暴露过MFs的个体，其神经内分泌-免疫系统与脂质代谢系统对热胁迫的易感性显著升高。综上，本研究证实了纺织微纤维可直接引发细胞效应，明确了合成来源与天然来源微纤维之间的差异，并揭示了纺织微纤维能够调控生物对其他胁迫因子的易感性——这与未来海洋生态系统变化中预测的胁迫因子效应一致。