Meeting Abstract
The great diversity and success of molluscs can partially be attributed to their ability to secrete diverse biomineralized structures. Aplacophora is a group of vermiform molluscs that lack a shell but are instead covered with calcareous scales or spines called sclerites. Aplacophoran sclerites are composed of calcium carbonite polymorphs like conchiferan (e.g., gastropod and bivalve) shells, but homology of these different biomineralized structures has not been tested. Transcriptomic and proteomic approaches have provided insight into the genes and proteins responsible for patterning the shells of conchiferan molluscs. These studies have shown the expression of both highly conserved and lineage-specific genes in mantle transcriptomes of distantly related mollusc species. Investigation into the biomineralization toolkit of aplacophoran is needed. Here, we present an ongoing project aimed at addressing these questions focusing on draft assemblies of the solenogaster aplacophorans Neomenia megatrapezata and Epimenia babai. Our sequencing strategy combined Illumina HiSeq X paired-end reads and multiple flow cells of Oxford Nanopore GridION long reads to produce hybrid assemblies using MaSuRCA. Assemblies will be scaffolded with optical mapping and subsequently annotated to identify genes involved in biomineralization. Proteomics will be used to confirm protein products within the sclerites and expression patterns will be examined in larvae using in situ hybridization. This work will shed light on the formation of sclerites, their homology to conchiferan shells, and the biomineralization toolkit of the last common ancestor of Mollusca.
