Genes with spiralian-specific protein motifs are expressed in spiralian ciliary bands

Longjun Wu,Yale Passamaneck,Benjamin R Bastin,Elaine C Seaver,Svetlana A Maslakova,Marleen Klann,Mark Q Martindale,Laurel S Hiebert,J David Lambert,Stephan Q Schneider

doi:10.1038/s41467-020-17780-7

Abstract

Spiralia is a large, ancient and diverse clade of animals, with a conserved early developmental program but diverse larval and adult morphologies. One trait shared by many spiralians is the presence of ciliary bands used for locomotion and feeding. To learn more about spiralian-specific traits we have examined the expression of 20 genes with protein motifs that are strongly conserved within the Spiralia, but not detectable outside of it. Here, we show that two of these are specifically expressed in the main ciliary band of the mollusc Tritia (also known as Ilyanassa). Their expression patterns in representative species from five more spiralian phyla—the annelids, nemerteans, phoronids, brachiopods and rotifers—show that at least one of these, lophotrochin, has a conserved and specific role in particular ciliated structures, most consistently in ciliary bands. These results highlight the potential importance of lineage-specific genes or protein motifs for understanding traits shared across ancient lineages.

Highlights

Spiralia is a large, ancient and diverse clade of animals, with a conserved early developmental program but diverse larval and adult morphologies
We carry out a screen for genes that are restricted to the Spiralia, because we wonder whether these might be involved with spiralianspecific traits
To find genes that have arisen de novo or evolved new functions in the spiralian common ancestor, we carried out a bioinformatic screen for protein sequences that are strongly conserved within the Spiralia, but are not recognizable or poorly conserved in other organisms

Summary

Introduction

Ancient and diverse clade of animals, with a conserved early developmental program but diverse larval and adult morphologies. We show that two of these are expressed in the main ciliary band of the mollusc Tritia ( known as Ilyanassa) Their expression patterns in representative species from five more spiralian phyla—the annelids, nemerteans, phoronids, brachiopods and rotifers—show that at least one of these, lophotrochin, has a conserved and specific role in particular ciliated structures, most consistently in ciliary bands. These results highlight the potential importance of lineage-specific genes or protein motifs for understanding traits shared across ancient lineages. These results highlight the potential importance of lineage-specific genes or protein motifs for understanding phenotypic evolution

Methods

Results

Conclusion