Stage-Specific Transcriptomes of the Mussel Mytilus coruscus Reveals the Developmental Program for the Planktonic to Benthic Transition

Abstract

Many marine invertebrate larvae undergo complex morphological and physiological changes during the planktonic—benthic transition (a.k.a. metamorphosis). In this study, transcriptome analysis of different developmental stages was used to uncover the molecular mechanisms underpinning larval settlement and metamorphosis of the mussel, Mytilus coruscus. Analysis of highly upregulated differentially expressed genes (DEGs) at the pediveliger stage revealed enrichment of immune-related genes. The results may indicate that larvae co-opt molecules of the immune system to sense and respond to external chemical cues and neuroendocrine signaling pathways forecast and trigger the response. The upregulation of adhesive protein genes linked to byssal thread secretion indicates the anchoring capacity required for larval settlement arises prior to metamorphosis. The results of gene expression support a role for the immune and neuroendocrine systems in mussel metamorphosis and provide the basis for future studies to disentangle gene networks and the biology of this important lifecycle transformation.

Balancing selection and candidate loci for survival and growth during larval development in the Mediterranean mussel, Mytilus galloprovincialis

“…This foot allows the bivalve larvae to seek a suitable place to perform metamorphosis—the transition from free-swimming larvae to a sessile juvenile by secretion of a bioadhesive material or via byssal threads—and it is during this metamorphosis where many commercial hatcheries observe significant mortality episodes. Metamorphosis is 1 of the most important life history events for bivalves, and several transcriptomic studies across many species demonstrate significant expression profile changes at this stage ( Niu et al 2016 ; Foulon et al 2019 ; Hao et al 2019 ; Wang et al 2023 ). For the Mediterranean mussel, Mytilus galloprovincialis , transcriptomic studies focusing on metamorphosis show enrichment of differentiation and biosynthesis transcripts, perhaps at the expense of their health: immune-related transcripts decrease during this stage ( Moreira et al 2018 ).…”