Ninghai Institute of Mariculture Breeding and Seed Industry, Zhejiang Wanli University, Ninghai, 315604, China.
Zhejiang Key Laboratory of Aquatic Germplasm Resource, Zhejiang Wanli University, Ningbo, 315100, China.
BMC Genomics. 2022 May 18;23(1):378. doi: 10.1186/s12864-022-08610-9.
Oysters inhabit in the intertidal zone and may be suffered from environmental stresses, which can increase the production of reactive oxygen species (ROS), resulting in mass mortality. Superoxide dismutases (SODs) protect oysters from ROS damage through different mechanisms compared with vertebrates. However, the molecular and functional differentiation in oyster SODs were rarely analyzed.
In this study, a total of 13, 13, 10, and 8 candidate SODs were identified in the genome of Crassostrea gigas, Crassostrea virginica, Crassostrea hongkongensis, and Saccostrea glomerata respectively. The domain composition, gene structure, subcellular locations, conserved ligands, and cis-elements elucidated the SODs into five groups (Mn-SODs, Cu-only-SODs, Cu/Zn ion ligand Cu/Zn-SOD with enzyme activity, Zn-only-SODs, and no ligand metal ions Cu/Zn-SODs). For single domain Cu/Zn-SODs, only one cytosolic Cu/Zn-SOD (cg_XM_034479061.1) may conserve enzymatic activity while most extracellular Cu/Zn-SOD proteins appeared to lose SOD enzyme activity according to conserved ligand amino acid analysis and expression pattern under biotic and abiotic stress in C. gigas. Further, multi-domain-SODs were identified and some of them were expressed in response to biotic and abiotic stressors in C. gigas. Moreover, the expression patterns of these genes varied in response to different stressors, which may be due to the cis-elements in the gene promoter.
These findings revealed the most extracellular Cu/Zn-SOD proteins appeared to lose SOD enzyme activity in oysters. Further, our study revealed that only one cytosolic Cu/Zn-SOD (cg_XM_034479061.1) may conserve enzymatic activity of SOD. Moreover, the expression patterns of these genes varied in response to different stressors, which may be due to the cis-elements in the promoter. This study provides important insights into the mechanisms through which oysters adapt to harsh intertidal conditions, as well as potential biomarkers of stress response in related species.
牡蛎栖息在潮间带，可能会受到环境压力的影响，这会导致活性氧（ROS）的产生增加，从而导致大量死亡。超氧化物歧化酶（SODs）通过与脊椎动物不同的机制来保护牡蛎免受 ROS 的损伤。然而，牡蛎 SOD 的分子和功能分化很少被分析。
在这项研究中，在巨牡蛎（Crassostrea gigas）、弗吉尼亚牡蛎（Crassostrea virginica）、中国香港牡蛎（Crassostrea hongkongensis）和光滑石房蛤（Saccostrea glomerata）的基因组中分别鉴定出了 13、13、10 和 8 个候选 SOD。结构域组成、基因结构、亚细胞定位、保守配体和顺式元件将 SOD 分为 5 组（Mn-SODs、Cu 单加氧酶 SODs、具有酶活性的 Cu/Zn 离子配体 Cu/Zn-SODs、Zn 单加氧酶 SODs 和无配体金属离子 Cu/Zn-SODs）。对于单一结构域 Cu/Zn-SODs，只有一个胞质 Cu/Zn-SOD（cg_XM_034479061.1）可能具有酶活性，而大多数细胞外 Cu/Zn-SOD 蛋白似乎根据保守配体氨基酸分析和在巨牡蛎中生物和非生物胁迫下的表达模式而失去 SOD 酶活性。此外，鉴定出多结构域 SODs，其中一些在巨牡蛎中对生物和非生物胁迫因子有表达。此外，这些基因的表达模式因不同的胁迫因子而不同，这可能是由于基因启动子中的顺式元件。
这些发现表明，牡蛎中大多数细胞外 Cu/Zn-SOD 蛋白似乎失去了 SOD 酶活性。此外，我们的研究表明，只有一个胞质 Cu/Zn-SOD（cg_XM_034479061.1）可能具有 SOD 的酶活性。此外，这些基因的表达模式因不同的胁迫因子而不同，这可能是由于启动子中的顺式元件。这项研究为牡蛎适应恶劣潮间带条件的机制以及相关物种应激反应的潜在生物标志物提供了重要的见解。
