Genome and Transcriptome Analyses Provide Insight into the Euryhaline Adaptation Mechanism of Crassostrea gigas

Abstract

BackgroundThe Pacific oyster, Crassostrea gigas, has developed special mechanisms to regulate its osmotic balance to adapt to fluctuations of salinities in coastal zones. To understand the oyster’s euryhaline adaptation, we analyzed salt stress effectors metabolism pathways under different salinities (salt 5, 10, 15, 20, 25, 30 and 40 for 7 days) using transcriptome data, physiology experiment and quantitative real-time PCR.ResultsTranscriptome data uncovered 189, 480, 207 and 80 marker genes for monitoring physiology status of oysters and the environment conditions. Three known salt stress effectors (involving ion channels, aquaporins and free amino acids) were examined. The analysis of ion channels and aquaporins indicated that 7 days long-term salt stress inhibited voltage-gated Na+/K+ channel and aquaporin but increased calcium-activated K+ channel and Ca2+ channel. As the most important category of osmotic stress effector, we analyzed the oyster FAAs metabolism pathways (including taurine, glycine, alanine, beta-alanine, proline and arginine) and explained FAAs functional mechanism for oyster low salinity adaptation. FAAs metabolism key enzyme genes displayed expression differentiation in low salinity adapted individuals comparing with control which further indicated that FAAs played important roles for oyster salinity adaptation. A global metabolic pathway analysis (iPath) of oyster expanded genes displayed a co-expansion of FAAs metabolism in C. gigas compared with seven other species, suggesting oyster’s powerful ability regarding FAAs metabolism, allowing it to adapt to fluctuating salinities, which may be one important mechanism underlying euryhaline adaption in oyster. Additionally, using transcriptome data analysis, we uncovered salt stress transduction networks in C. gigas.ConclusionsOur results represented oyster salt stress effectors functional mechanisms under salt stress conditions and explained the expansion of FAAs metabolism pathways as the most important effectors for oyster euryhaline adaptation. This study was the first to explain oyster euryhaline adaptation at a genome-wide scale in C. gigas.

Cysteine dioxygenase and cysteine sulfinate decarboxylase genes of the deep-sea mussel Bathymodiolus septemdierum: possible involvement in hypotaurine synthesis and adaptation to hydrogen sulfide

“…Despite hypotaurine/taurine being major components of mollusk tissues, enzymes catalyzing hypotaurine synthesis in mollusks have not been identified. However, some papers reported enzymatic activities related to hypotaurine/taurine synthesis (Allen and Awapara 1960;Yoneda 1968), and there is evidence by way of annotation on the oyster genome and transcriptome (Zhang et al 2012;Meng et al 2013).…”

Respuesta fisiológica y molecular de Anadara tuberculosa (Arcoida: Arcidae) al estrés de salinidad

“…Estudios previos han demostrado que los FAAs intracelulares son los principales contribuyentes a la regulación de la osmolaridad intracelular y del volumen celular en bivalvos (Gosling, 2015). En este trabajo se diseñó 18 marcadores moleculares asociados al sistema de regulación por FAAs, y uno a partir de la proteína de estrés (HSP70), usando las secuencias disponibles publicadas de cuatro bivalvos modelos: las ostras C. gigas, C. angulata, C. virginica y el mejillón M. galloprovincialis (Meng et al, 2013;Cross et al, 2014;Eierman & Hare, 2014).…”

“…Los genes de interés evaluados para este estudio fueron: Aminomethyltransferase, Glycine dehydrogenase, Glycine hydroxymethyltransferase, Δ-1-pyrroline-5-carboxylate synthase, Ornithine aminotransferase, Arginase, Alanine transaminase, Alanine-glyoxylate transaminase, Glutamate decarboxylase, Glutamate decarboxylase 1-2, Spermidine synthase, Aldehyde dehydrogenase, ATP-grasp domain-containing protein, Cysteine sulfinic acid decarboxylase1-2, Taurine transporter, HSP beta 1, Sodium-and chloride-dependent glycine transporter (Meng et al, 2013;Cross et al, 2014;Eierman & Hare, 2014).…”

“…Los principales mecanismos de adaptación a diferentes salinidades de la ostra y del mejillón han sido caracterizados a nivel molecular (Cross, Merlo, Rodríguez, Portela-Bens, & Rebordinos, 2014;Eierman & Hare, 2014); en particular, Meng et al (2013), resaltaron la primordial importancia de las vías de metabolismo de los FAAs para la adaptación eurihalina de la ostra Crassostrea gigas. A pesar que la mayoría de los trabajos han sido realizados en diferentes especies de bivalvos, es muy probable que los mecanismos de osmorregulación se conserven a nivel inter-específico.…”

Mild osmotic stress in intertidal gastropods Littorina saxatilis and Littorina obtusata (Mollusca: Caenogastropoda): a proteomic analysis

“…Osmotic stress deeply affects various physiological processes, including those in nervous, immune and other systems (Stucchi-Zucchi and Salomao, 1998;Cheng et al, 2004;Bussell et al, 2008;Jauzein et al, 2013;Honorato et al, 2017). Considerable progress has been made in recent years in our understanding of the molecular background of salinity adaptation (An and Choi, 2010;Hoy et al, 2012;Lockwood and Somero, 2011;Zhao et al, 2012;Tomanek et al, 2012;Meng et al, 2013;Seveso et al, 2013;Carregosa et al, 2014;Muraeva et al, 2016;Gharbi et al, 2016;Yang et al, 2016;Yan et al, 2017). Nevertheless, greater knowledge about the physiological mechanisms of adaptation to salinity variation is still needed, especially in regard to intertidal invertebrates, which deal with osmotic stress throughout their lives.…”