Gaillard Sylvain, Small Hamish J, Carnegie Ryan B, Harris Thomas M, Tanniou Simon, Réveillon Damien, Hess Philipp, Reece Kimberly S
Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, USA.
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA.
J Aquat Anim Health. 2024 Dec;36(4):374-394. doi: 10.1002/aah.10227.
The dinoflagellate Alexandrium monilatum forms blooms during summer in tributaries of the lower Chesapeake Bay. Questions persist about the potential for A. monilatum to negatively affect aquatic organisms. Its main toxin, goniodomin A (GDA), a polyketide macrolide, has been shown to have adverse effects on animals, for example through cytotoxicity and interaction with actin.
Eastern oysters Crassostrea virginica were exposed for 96 h to sublethal concentrations of A. monilatum (615 ± 47 cells/mL [average ± SD]; containing mainly intracellular GDA [215 ± 7.15 pg/cell] and to a lesser extent goniodomin B, goniodomin C, and GDA seco-acid as quantified by liquid chromatography coupled to tandem mass spectrometry) or to nontoxic phytoplankton or were unexposed. They were subsequently depurated for 96 h by exposure to nontoxic phytoplankton. Clearance rates were estimated, and oysters were sampled daily and tissue (gill, digestive gland, and remaining tissues) excised for analyses by histopathology, gene expression quantified by quantitative PCR, and goniodomin quantification.
A positive clearance rate, no mortality, and no tissue pathologies were observed in oysters exposed to A. monilatum. Goniodomin A was detected in gill 6 h after exposure (504 ± 329 μg/kg [average ± SE]) and to a lesser extent in the digestive gland and remaining soft tissues. In the digestive gland, a trend of transformation of GDA to GDA seco-acid was observed. The majority of toxins (≥83%) were depurated after 96 h. Expression of genes involved in oxidative response increased 14-fold after 6 h, and those involved in actin synthesis showed a 27-fold change after 24 h, while expression of apoptosis genes increased 6.9-fold after 96 h compared with the control (eastern oysters exposed to nontoxic phytoplankton).
Exposure experiments (nonsublethal or chronic) should be carried out to better assess the threat of this species and toxins for eastern oysters and other marine organisms.
海洋甲藻链状亚历山大藻（Alexandrium monilatum）在切萨皮克湾下游支流的夏季形成水华。关于链状亚历山大藻对水生生物产生负面影响的可能性，仍存在疑问。其主要毒素膝沟藻毒素A（GDA）是一种聚酮类大环内酯，已被证明对动物有不良影响，例如通过细胞毒性和与肌动蛋白的相互作用。
将弗吉尼亚州东部牡蛎（Crassostrea virginica）暴露于亚致死浓度的链状亚历山大藻（615±47个细胞/毫升[平均值±标准差]；主要含有细胞内GDA[215±7.15皮克/细胞]，通过液相色谱-串联质谱法定量分析，还含有少量的膝沟藻毒素B、膝沟藻毒素C和GDA裂酸）96小时，或暴露于无毒浮游植物，或不进行暴露处理。随后，通过暴露于无毒浮游植物使其净化96小时。估计清除率，每天对牡蛎进行采样，并切除组织（鳃、消化腺和其余组织）用于组织病理学分析、通过定量PCR定量基因表达以及定量分析膝沟藻毒素。
暴露于链状亚历山大藻的牡蛎呈现出正清除率，无死亡情况，且未观察到组织病变。暴露6小时后，在鳃中检测到膝沟藻毒素A（504±329微克/千克[平均值±标准误]），在消化腺和其余软组织中的含量较低。在消化腺中，观察到GDA向GDA裂酸转化的趋势。96小时后，大部分毒素（≥83%）被净化。与氧化应激相关的基因表达在6小时后增加了14倍，与肌动蛋白合成相关的基因表达在24小时后变化了27倍，而与凋亡相关的基因表达在96小时后比对照组（暴露于无毒浮游植物的东部牡蛎）增加了6.9倍。
应进行暴露实验（非亚致死或慢性），以更好地评估该物种及其毒素对东部牡蛎和其他海洋生物的威胁。
