The Mantle Transcriptome of Chamelea gallina (Mollusca: Bivalvia) and Shell Biomineralization

Abstract

The striped venus Chamelea gallina is a bivalve mollusc that represents one of the most important fishery resources of the Adriatic Sea. In this work, we investigated for the first time the ability of this species to modulate the expression of genes encoding proteins involved in biomineralization process in response to biotic and abiotic factors. We provided the first comprehensive transcriptome from the mantle tissue of clams collected in two sampling sites located along the Italian Adriatic coast and characterized by different environmental features. Moreover, the assessment of environmental parameters, scanning electron microscopy (SEM), and X-ray diffraction (XRD) measurements on valves were conducted to better contextualize RNA sequencing (RNA-Seq) data. Functional annotation of differentially expressed genes (DEGs) and SEM observations highlighted a different shell mineralization behaviour in C. gallina clams collected from two selected sites characterized by diverse environmental parameters.

Keywords: biomineralization; gene expression analysis; mollusc; transcriptomics.

Figure 1

Geographical localization of sampling sites considered in the present work.

Figure 2

Circos plot obtained from functional enrichment analysis performed on differentially expressed genes derived from the comparison S vs. SM.

Figure 3

Scanning electron microscopy (SEM) observations obtained at 500× of magnification. (A–C) are referred to specimens of the Senigallia (S) sampling site. (D–F) are referred to specimens of the Silvi Marina (SM) sampling site.

Figure 4

Timeseries of environmental parameters. Daily temperature, salinity, and chlorophyll at the sampling stations of Senigallia (S, red line) and Silvi Marina (SM, black line) were reported. Computed monthly means are superimposed as circles.