Zeng Yangqing, Zeng Xianyuan, Yee Jayme C, Yang Huiping
School of Forest, Fisheries, and Geomatics Sciences, Institute of Food and Agricultural Sciences, University of Florida, 7922 NW 71st Street, Gainesville, FL, 32653, USA.
School of Forest, Fisheries, and Geomatics Sciences, Institute of Food and Agricultural Sciences, University of Florida, 7922 NW 71st Street, Gainesville, FL, 32653, USA.
Fish Shellfish Immunol. 2025 Nov;166:110609. doi: 10.1016/j.fsi.2025.110609. Epub 2025 Jul 31.
The goal of this study was to evaluate effects of short-term acute salinity challenges on the hemocyte physiology in northern quahogs, Mercenaria mercenaria, an important aquaculture species in the U.S. The objectives were to: 1) challenge adult northern quahogs with salinities of 5, 15, 25 (control), 35, and 45 ppt; 2) evaluate cellular responses, including hemocyte concentration, viability, phagocytosis rate, ROS production, and lysosomal presence at 12 h, 24 h, 48 h, 72 h, 144 h, and 21 days post-challenge; and 3) evaluate the molecular response of hemocytes after 72 h challenge. M. mercenaria at 5, 15, 25, 35 ppt exposure showed no mortality, while at 45 ppt showed a 100 % mortality at day 7, reflecting better tolerance to hyposalinity. Changes of hemolymph osmolality at different salinities and exposure periods indicated M. mercenaria equilibrates with the environmental seawater within its tolerance range (15-35 ppt) as an osmoconformer. Hemocyte concentration increased significantly at 5, 15, and 45 ppt stress. Hemocyte immune functions exhibited a varied pattern in response to different salinity levels, enabling them to resolve stresses. The RNAseq of hemocytes revealed DEGs in response to salinity challenges, specifically enrichment of amino acid transporters (SLC2A5, SLC6A1, SLC5A8, SLC1A3, SLC25A38), immune response (CHAC2, MGST3, IRF1, and IRFD2) and cell signaling (Wnt, TRAIL-activated and Toll) pathway in hyper/hypo salinity groups, indicated their importance in salinity stress responses. This study provided critical insights into the cellular and molecular responses of M. mercenaria hemocytes to salinity challenges.
本研究的目的是评估短期急性盐度挑战对美国重要养殖物种硬壳蛤（Mercenaria mercenaria）血细胞生理的影响。目标如下：1）用5、15、25（对照）、35和45 ppt的盐度挑战成年硬壳蛤；2）评估细胞反应，包括挑战后12小时、24小时、48小时、72小时、144小时和21天的血细胞浓度、活力、吞噬率、活性氧产生和溶酶体存在情况；3）评估挑战72小时后血细胞的分子反应。暴露于5、15、25、35 ppt的硬壳蛤没有死亡，而暴露于45 ppt的硬壳蛤在第7天死亡率达100%，这表明其对低盐度的耐受性更强。不同盐度和暴露时期的血淋巴渗透压变化表明，硬壳蛤作为渗透压顺应者，在其耐受范围内（15 - 35 ppt）与环境海水达到平衡。在5、15和45 ppt胁迫下，血细胞浓度显著增加。血细胞免疫功能对不同盐度水平呈现出不同的反应模式，使其能够应对胁迫。血细胞的RNA测序揭示了响应盐度挑战的差异表达基因，特别是高/低盐度组中氨基酸转运体（SLC2A5、SLC6A1、SLC5A8、SLC1A3、SLC25A38）、免疫反应（CHAC2、MGST3、IRF1和IRFD2）和细胞信号传导（Wnt、TRAIL激活和Toll）途径的富集，表明它们在盐度胁迫反应中的重要性。本研究为硬壳蛤血细胞对盐度挑战的细胞和分子反应提供了重要见解。
