Another biomineralising protostome with an msp130 gene and conservation of msp130 gene structure across Bilateria

Abstract

SUMMARY Msp130 genes are known for their association with biomineralisation, principally in echinoderm skeletogenesis. Recently, msp130 genes were shown to exist more widely across the animal kingdom, including in molluscs, and a hypothesis was formed that the genes had arisen independently in the deuterostome and mollusc lineages via horizontal gene transfer, thus facilitating the evolution of biomineralisation in these distinct lineages (Ettensohn, 2014). Here we show that another biomineralising protostome, the polychaete Spirobranchus (formerly Pomatoceros) lamarcki also possesses an msp130 gene, and expresses it during a biomineralisation process. However, based on analysis of gene structure, we hypothesize that the protostome and deuterostome msp130 genes did not originate from independent horizontal gene transfers, but instead are descended from a gene already present in the bilaterian ancestor, with the gene being secondarily lost from several lineages.

Developmental transcriptomics of the brittle starAmphiura filiformisreveals gene regulatory network rewiring in echinoderm larval skeleton evolution

“…Indication of clade specific expansions took place is strongly supported by our phylogenetic analysis (SFig. 6), which shows a consistent group of sea urchin Msp130 genes with various paralogues represented in both sea urchin species analysed ( S. purpuratus and L. variegatus ), a different group of Ophiuroid Msp130s , as well as other clade specific expansions consistent with what has already shown for Msp130 genes in molluscs and anellids (Szabó & Ferrier 2015). Concerning the spicule matrix (sm) genes, out of the 14 genes identified in sea urchin only the C-lectin that does not contain a proline rich region is conserved in all four species.…”

Developmental transcriptomics of the brittle star Amphiura filiformis reveals gene regulatory network rewiring in echinoderm larval skeleton evolution

“…An in-depth look into the brittle star transcriptome, using a hidden Markov model, revealed also the presence of seven other msp130 contigs that show differences at the amino acid level higher than the 1.2 % of polymorphism identified in the coding region, suggesting the presence of several genes. Indication that clade-specific expansions took place is strongly supported by our phylogenetic analysis (Additional file 1 : Figure S6), which shows a consistent group of sea urchin Msp130 genes with various paralogues represented in both sea urchin species analysed ( S. purpuratus and L. variegatus ), a different group of ophiuroid Msp130s , as well as other clade-specific expansions consistent with what has already been shown for Msp130 genes in molluscs and annelids [ 55 ]. Concerning the spicule matrix (sm) genes, out of the 14 genes identified in sea urchin only the C-lectin that does not contain a proline-rich region is conserved in all four species.…”

Genomic insights of body plan transitions from bilateral to pentameral symmetry in Echinoderms

“…The MSP130 gene was suggested to have originated in prokaryotes and was introduced into metazoan genomes, including echinoderms, by horizontal gene transfer 32 . An MSP130-like gene involved in biomineralization has also been identified in a polychaete 33 . The authors suggest that the MSP130 gene was present in the common ancestor to bilaterians, rather than being introduced into protostomes and deuterostomes in separate lateral transfer events.…”