Abstract

Shell color is one of the shell traits of molluscs, which has been regarded as an economic trait in some bivalves. Pacific oysters (Crassostrea gigas) are important aquaculture shellfish worldwide. In the past decade, several shell color strains of C. gigas were developed through selective breeding, which provides valuable materials for research on the inheritance pattern and regulation mechanisms of shell color. The inheritance patterns of different shell colors in C. gigas have been identified in certain research; however, the regulation mechanism of oyster pigmentation and shell color formation remains unclear. In this study, we performed transcriptomic and physiological analyses using black and white shell oysters to investigate the molecular mechanism of melanin synthesis in C. gigas. Several pigmentation-related pathways, such as cytochrome P450, melanogenesis, tyrosine metabolism, and the cAMP signaling pathway were found. The majority of differentially expressed genes and some signaling molecules from these pathways exhibited a higher level in the black shell oysters than in the white, especially after l-tyrosine feeding, suggesting that those differences may cause a variation of tyrosine metabolism and melanin synthesis. In addition, the in vitro assay using primary cells from mantle tissue showed that l-tyrosine incubation increased cAMP level, gene and protein expression, and melanin content. This study reveals the difference in tyrosine metabolism and melanin synthesis in black and white shell oysters and provides evidence for the potential regulatory mechanism of shell color in oysters.

中文翻译：

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转录组学和生理学分析揭示太平洋牡蛎（Crassostrea gigas）黑色素合成相关基因和途径

摘要

贝壳颜色是软体动物的贝壳性状之一，在一些双壳类动物中被视为一种经济性状。太平洋牡蛎（Crassostrea gigas）是全世界重要的水产养殖贝类。近十年来，通过选育，培育出数个巨型巨鳅壳色品系，为研究巨鲆壳色的遗传模式和调控机制提供了宝贵的材料。某些研究已经确定了巨龟不同壳色的遗传模式；然而，牡蛎色素沉着和贝壳颜色形成的调节机制仍不清楚。在本研究中，我们利用黑白贝牡蛎进行转录组学和生理学分析，以研究C. gigas 黑色素合成的分子机制。发现了一些与色素沉着相关的通路，如细胞色素 P450、黑素生成、酪氨酸代谢和 cAMP 信号通路。来自这些途径的大多数差异表达基因和一些信号分子在黑壳牡蛎中表现出比白壳牡蛎更高的水平，特别是在摄食L-酪氨酸后，表明这些差异可能导致酪氨酸代谢和黑色素合成的变化。此外，使用来自套组织的原代细胞进行的体外测定表明，L-酪氨酸孵育增加了cAMP水平、基因和蛋白质表达以及黑色素含量。该研究揭示了黑白贝牡蛎酪氨酸代谢和黑色素合成的差异，为牡蛎贝壳颜色的潜在调节机制提供了证据。