eSnail: a transcriptome-based molecular resource of the central nervous system for terrestrial gastropods.

To expand on emerging terrestrial gastropod molecular resources, we have undertaken transcriptome-based sequencing of the central nervous system (CNS) from six ecologically invasive terrestrial gastropods. Focusing on snail species Cochlicella acuta and Helix aspersa and reticulated slugs Deroceras invadens, Deroceras reticulatum, Lehmannia nyctelia and Milax gagates, we obtained a total of 367,869,636 high-quality reads and compared them with existing CNS transcript resources for the invasive Mediterranean snail, Theba pisana. In total, we obtained 419,289 unique transcripts (unigenes) from 1,410,569 assembled contigs, with blast search analysis of multiple protein databases leading to the annotation of 124,268 unigenes, of which 92,544 mapped to NCBI nonredundant protein databases. We found that these transcriptomes have representatives in most biological functions, based on comparison of gene ontology, kegg pathway and protein family contents, demonstrating a high range of transcripts responsible for regulating metabolic activities and molecular functions occurring within the CNS. To provide an accessible genetic resource, we also demonstrate the presence of 66,687 microsatellites and 304,693 single-nucleotide variants, which can be used for the design of potentially thousands of unique primers for functional screening. An online "eSnail" database with a user-friendly web interface was implemented to query all the information obtained herein (http://soft.bioinfo-minzhao.org/esnail). We demonstrate the usefulness of the database through the mining of molluscan neuropeptides. As the most comprehensive CNS transcriptome resource for terrestrial gastropods, eSnail may serve as a useful gateway for researchers to explore gastropod CNS function for multiple purposes, including for the development of biocontrol approaches.