RNAseq time studies of development stages in Pinctada margaritifera. Quanapa - larvaire

Background: Early development stages in marine bivalve are critical periods where larvae transition from pelagic free-life to sessile mature individual. The successive metamorphosis solicit key genes and functions which might be responsible for high selective pressure, hence, understanding larvae development should be a key knowledge for both fundamental and applied research. Phenotypic larvae development is well known, but the underlying molecular mechanisms such as associated gene expression dynamic and molecular cross-talks remain poorly described for several non-model species, such as P. margaritifera. We designed a whole transcriptome RNA-sequencing analysis to describe such gene expression dynamic following four larval developmental stages: D-shape, Veliger, Umbo and Eye-spot Results: Larvae functioning drastically diverge across stages, which coincide with differential tissue organization. Metabolism (lipids, amino acids and carbohydrates) is highly solicited in the first development stages, with increasing demand from D-shape to umbo. Morphogenesis and larval transition are partly ordered by Thyroid hormones and Wnt signaling. While larvae shells show some similar characteristic to adults’ shells, the actors of initialization of biomineralization differ from the one found in adults. Conclusions: The present study provides a global overview of Pinctada Margaritifera larval stages provided knowledge on the gene expression dynamics, molecular mechanisms and ontogeny of biomineralization, immune system, and sensory perception processes.