Effects Of Ocean Acidification On Gene Expression Of Fujian Oyster(Crassostrea Angulata) Larvae

Nowadays anthropogenic CO2emissions are acidifying the world’s oceans. A growing body of researches on calcifying marine invertebrates demonstrate that ocean acidification can impact survival, growth, development and physiology. However, limited information was available concerning the impacts of ocean acidification on Fujian oyster Crassostrea angulata larvae. In laboratory experiments designed to mimic seawater chemistry in future oceans, we tested the impacts of short-term exposure to elevated pCO2(1500ppm and3000ppm, compared to control400ppm) on Crassostrea angulate, one of the most important economic aquaculture varieties. In this study, we use morphology technology and molecular technology to study the Crassostrea angulata larvae after exposed to ocean acidification. The main results are as follows:1.The influence of ocean acidification on shell development of Crassostrea angulata larvaeWe found that1500ppm pCO2exposure had no significant influence on Crassostrea angulata larvae, while the larvae exposed to3000ppm pCO2were smaller than those cultured in control, and the shell growth was slower. In additional, the aberration rate of larvae was increased. Further we found that ocean acidification certainly inhibited the calcium deposition of Crassostrea angulata4days D-veligers using Scanning electron microscope combined with energy disperse spectroscopy analysis. Furthermore we concluded that Crassostrea angulata larvae can tolerate the impaction of ocean acidification at1500ppm PCO2.2.The digital gene expression profiles analysis of Crassostrea angulata larvae after exposed to ocean acidificationDigital gene expression profiles of Crassostrea angulata trochophores, early D-veligers and4days D-veligers after ocean acidification exposure were assessed. After comparing with controls we respectively got5317,74and2641differentially expressed genes. Gene ontology enrichment analysis and Pathway enrichment analysis for the differentially expressed genes showed that ocean acidification mainly inhibited the genes and pathways participated in embryonic development, energy metabolism and calcium ion conduction, thus leading to the delay of larvae growth.3.The preliminary study on the genes involved in the formation and development of Crassostrea angulata larvae shell after exposed to ocean acidificationThrough the whole mount in situ hybridization (WISH) we found Tyr3, TGF-β signalling pathway and BMP signalling pathway are involved in the biogenesis of Crassostrea angulata larvae InCaS. Under ocean acidification, the expression of genes involved in TGF-β signalling pathway was restrained, while Tyr3and genes participated in BMP signalling pathway upregulated their expression. However, the results of the morphological study released that larvae shells can still grow in a slower rate, and the aberration rate was increased. Therefore, we suggested that the upregulation of Tyr3and BMP signalling pathway cannot compensate the damage of ocean acidification.We use Scanning electron microscope combined with energy disperse spectroscopy analysis to study the impacts of ocean acidification on the shell elements. The results released that the calcium deposition was inhibited by ocean acidification. We took good advantages of RNA-Seq technology to evaluate the influences of ocean acidification on Crassostrea angulata larvae during early development. We found that ocean acidification mainly inhibited the function of signalling pathways which involved in the early embryonic development, energy metabolism and calcium ion conduction, thus led to the delay in larvae growth. Using the whole mount in situ hybridization to explore the function of Tyr3and genes involved in TGF-β and BMP signalling pathways. The results showed that these genes were concerned with InCaS biogenesis and shell development. Further we used qRT-PCR to explore the gene expression patterns under ocean acidification. We found that the genes involved in the TGF-β signalling pathway were downregulated their expression, while the expression of Tyr3and genes involved in BMP signalling pathway were increased. Considering the results of morphology researches, we supposed that after exposed to ocean acidification, the upregulated expression of some genes and signaling pathways cannot compensate the damage of ocean acidification to larvae, so that the gowth of larvae shell was decreased and the abnormality was elevated.