Duan Guochao, Chen Xiubao, Hou Yiran, Jiang Tao, Liu Hongbo, Yang Jian
Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China.
Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China; Laboratory of Fishery Microchemistry, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China.
Comp Biochem Physiol Part D Genomics Proteomics. 2024 Dec;52:101359. doi: 10.1016/j.cbd.2024.101359. Epub 2024 Nov 12.
Nitrite contamination and stress on aquatic organisms are increasingly emphasized in freshwater ecosystems. Freshwater bivalves exhibit high tolerance to nitrite; however, the underlying mechanism is unknown. Accordingly, this study investigated the tolerance mechanism of the globally occurring freshwater bivalve Anodonta woodiana. A. woodiana were exposed to nominal concentrations of 0, 250, 500, 1000, 2000, and 4000 mg/L nitrite for 96 h to calculate the 96-h median lethal concentration (96-h LC). A combined transcriptome and metabolome analysis of the hemolymph (the most vital component of the bivalve immune system) was performed after exposing A. woodiana to 300 mg/L nitrite (approximately half the 96-h LC) for 96 h. The 96-h LC of nitrite in A. woodiana was 618.7 mg/L. Transcriptome analysis identified 5600 differentially expressed genes (DEGs) primarily related to ribosomes, lysosomes, DNA replication, and nucleotide excision repair. Metabolome analysis identified 216 differentially expressed metabolites (DEMs) primarily involved in biosynthesis of amino acids, 2-oxocarboxylic acid metabolism, protein digestion and absorption, aminoacyl-tRNA biosynthesis, nucleotide metabolism, ABC transporters, and valine, leucine and isoleucine degradation. Combined transcriptome and metabolome analysis revealed that DEGs and DEMs were primarily associated with nucleotide (purine and pyrimidine) and amino acid metabolism (including aminoacyl-tRNA biosynthesis, cysteine and methionine metabolism, arginine and proline metabolism, and valine, leucine and isoleucine degradation) as well as the immune system (necroptosis and glutathione metabolism). This study is the first to describe the high tolerance of A. woodiana to nitrite and elucidate the molecular mechanisms underlying high nitrite tolerance in mussels.
在淡水生态系统中，亚硝酸盐污染以及对水生生物的胁迫日益受到关注。淡水双壳贝类对亚硝酸盐表现出较高的耐受性；然而，其潜在机制尚不清楚。因此，本研究调查了全球广泛分布的淡水双壳贝类背角无齿蚌的耐受机制。将背角无齿蚌暴露于名义浓度为0、250、500、1000、2000和4000 mg/L的亚硝酸盐中96小时，以计算96小时半数致死浓度（96-h LC）。在将背角无齿蚌暴露于300 mg/L亚硝酸盐（约为96-h LC的一半）96小时后，对其血淋巴（双壳贝类免疫系统最重要的组成部分）进行了转录组和代谢组联合分析。背角无齿蚌中亚硝酸盐的96-h LC为618.7 mg/L。转录组分析鉴定出5600个差异表达基因（DEG），主要与核糖体、溶酶体、DNA复制和核苷酸切除修复有关。代谢组分析鉴定出216个差异表达代谢物（DEM），主要参与氨基酸生物合成、2-氧代羧酸代谢、蛋白质消化和吸收、氨酰-tRNA生物合成、核苷酸代谢、ABC转运蛋白以及缬氨酸、亮氨酸和异亮氨酸降解。转录组和代谢组联合分析表明，DEG和DEM主要与核苷酸（嘌呤和嘧啶）和氨基酸代谢（包括氨酰-tRNA生物合成、半胱氨酸和甲硫氨酸代谢、精氨酸和脯氨酸代谢以及缬氨酸、亮氨酸和异亮氨酸降解）以及免疫系统（坏死性凋亡和谷胱甘肽代谢）有关。本研究首次描述了背角无齿蚌对亚硝酸盐的高耐受性，并阐明了贻贝中亚硝酸盐高耐受性的分子机制。
