Candidate Calcium-Binding Genes for Chemical Boring in the Date Mussel Lithophaga lithophaga

ABSTRACT The date mussel Lithophaga lithophaga is a chemical borer that uses pallial gland secretions to bore holes in the substrate. Calcium-binding proteins are generally considered to be responsible for the chemical dissolution of the calcareous substrate. The aim of this study was to investigate the relative expression of five candidate genes – ANXB9, SCP, CALR, PLA2 and V-ATPase – in four different tissues, with the hypothesis that the expression profile of the candidate genes in the pallial gland would differ from the rest. The results from gene expression analysis revealed that CALR, PLA2 and SCP were up-regulated in the pallial gland. Two of the candidate genes (ANXB9 and V-ATPase) had the same expression profile in all four investigated tissues, indicating that they are not directly involved in the chemical boring mechanism. The results of this study shed light on the genetic background of the chemical boring mechanism in date mussel. This set of candidate genes could be used in future research studies of chemical boring in the date mussel and other marine or freshwater borers.