Division of Environmental Toxicology, Department of BioMolecular Sciences, University of Mississippi, P.O. Box 1848, University, MS, 38677, USA.
School of Ocean Science and Engineering, University of Southern Mississippi, 703 East Beach Road, Ocean Springs, MS, 39564, USA.
Sci Rep. 2020 Jun 30;10(1):10605. doi: 10.1038/s41598-020-67650-x.
Oyster reefs are vital to estuarine health, but they experience multiple stressors and globally declining populations. This study examined effects of hypoxia and tributyltin (TBT) on adult Eastern oysters (Crassostrea virginica) exposed either in the laboratory or the field following a natural hypoxic event. In the laboratory, oysters were exposed to either hypoxia followed by a recovery period, or to hypoxia combined with TBT. mRNA expression of HIF1-α and Tβ-4 along with hemocyte counts, biomarkers of hypoxic stress and immune health, respectively, were measured. In field-deployed oysters, HIF1-α and Tβ-4 expression increased, while no effect on hemocytes was observed. In contrast, after 6 and 8 days of laboratory-based hypoxia exposure, both Tβ-4 expression and hemocyte counts declined. After 8 days of exposure to hypoxia + TBT, oysters substantially up-regulated HIF1-α and down-regulated Tβ-4, although hemocyte counts were unaffected. Results suggest that hypoxic exposure induces immunosuppression which could increase vulnerability to pathogens.
牡蛎礁对河口生态系统的健康至关重要，但它们面临着多种压力和全球数量下降的问题。本研究通过实验室和野外实验，调查了缺氧和三丁基锡（TBT）对暴露于自然缺氧事件后的成年美洲牡蛎（Crassostrea virginica）的影响。在实验室中，牡蛎分别暴露于缺氧后恢复或缺氧与 TBT 联合处理。分别测量了缺氧诱导因子 1-α（HIF1-α）和 Tβ-4 的 mRNA 表达以及血淋巴细胞计数，以评估缺氧应激和免疫健康的生物标志物。在野外部署的牡蛎中，HIF1-α和 Tβ-4 的表达增加，而血淋巴细胞计数没有观察到变化。相反，在实验室缺氧暴露 6 和 8 天后，Tβ-4 的表达和血淋巴细胞计数均下降。在缺氧+TBT 暴露 8 天后，牡蛎大量上调 HIF1-α和下调 Tβ-4，尽管血淋巴细胞计数没有变化。结果表明，缺氧暴露会导致免疫抑制，从而增加对病原体的易感性。
