Laboratoire des Sciences de l'Environnement Marin, UMR 6539 LEMAR (UBO/CNRS/IRD/Ifremer). Institut Universitaire Européen de la Mer, Rue Dumont d'Urville, Technopộle Brest-Iroise, Plouzané 29280, France.
Laboratoire des Sciences de l'Environnement Marin, UMR 6539 LEMAR (UBO/CNRS/IRD/Ifremer). Institut Universitaire Européen de la Mer, Rue Dumont d'Urville, Technopộle Brest-Iroise, Plouzané 29280, France.
Harmful Algae. 2024 Sep;138:102708. doi: 10.1016/j.hal.2024.102708. Epub 2024 Aug 8.
Domoic acid (DA) is a dangerous phycotoxin produced by several strains of diatoms of the genus Pseudo-nitzschia, and responsible for Amnesic Shellfish Poisoning (ASP) in humans. The increasingly intense ASP-outbreaks along the English Channel over the last three decades have forced persistent harvest closures of economically important and highly contaminated bivalve stocks exhibiting slow DA-depuration rates, like the king scallop Pecten maximus. Under this scenario, other pectinid species, such as the queen scallop Aequipecten opercularis have been empirically proposed as alternative resources to redress the high economic losses due to the banning of the exploitation of P. maximus. Nevertheless, the kinetics of DA depuration in A. opercularis have not been assessed so far, and its direct extraction after ASP-episodes could represent a serious threat to public health. Hence, the main objective of this work was to estimate the DA-depuration rate in the digestive gland (DG) of naturally contaminated scallops A. opercularis after a toxic Pseudo-nitzschia australis bloom subjected to experimental depuration in the laboratory for 30 days. This study also intended to go further in the knowledge about the anatomical distribution of DA in scallop tissues, and corroborate the implications of autophagy in DA-sequestration in the DG of this species as recently hypothesized. In the DG, the DA-depuration rate (0.018 day) suggested that even with toxin burdens as low as 40 mg⋅kg in the DG, queen scallops may remain contaminated for about 70 days, thus longer under intensely contamination scenarios. The subcellular analyses corroborated DA-sequestration mainly through late-autophagy within residual bodies in the DG, without differences in the frequencies of anti-DA labeled residual bodies across the entire depuration process. These results revealed that A. opercularis cannot be considered a fast DA-depurator, and represent a baseline knowledge for decision-making about harvesting natural beds of queen scallops after toxic Pseudo-nitzschia blooms. The findings of this work also represent a cornerstone for further research to accelerate DA-depuration in this species.
软骨藻酸（DA）是一种危险的藻毒素，由假交替单胞菌属的几种硅藻产生，会导致人类失忆贝类中毒（ASP）。在过去的三十年里，英吉利海峡沿岸 ASP 爆发的频率越来越高，迫使经济上重要的、受污染严重的双壳类贝类持续关闭，因为这些贝类的 DA 净化率较低，比如海湾扇贝。在这种情况下，已经有人从经验上提出，其他扇贝物种，如栉孔扇贝，作为替代资源，可以弥补因禁止开采海湾扇贝而造成的巨大经济损失。然而，迄今为止，栉孔扇贝中 DA 的净化动力学尚未得到评估，而且在 ASP 爆发后直接提取 DA 可能会对公众健康造成严重威胁。因此，这项工作的主要目的是估计在实验室中经过 30 天的实验净化后，受有毒假交替单胞菌属藻华污染的栉孔扇贝消化腺（DG）中 DA 的净化率。本研究还旨在进一步了解 DA 在扇贝组织中的解剖分布，并证实自噬在该物种 DG 中 DA 隔离的作用，这是最近提出的假设。在 DG 中，DA 的净化率（0.018 天）表明，即使 DG 中的毒素负荷低至 40mg·kg，女王扇贝可能仍会被污染约 70 天，因此在污染严重的情况下时间更长。亚细胞分析证实，DA 主要通过 DG 中残余体的晚期自噬来隔离，在整个净化过程中，抗 DA 标记的残余体的频率没有差异。这些结果表明，栉孔扇贝不能被视为快速的 DA 净化者，这为在有毒假交替单胞藻属藻华后对女王扇贝天然床进行收获决策提供了基线知识。这项工作的发现也为进一步研究加速该物种的 DA 净化奠定了基础。
