title: De novo transcriptome assembly, functional annotation and differential gene expression analysis of juvenile and adult E. fetida, a model oligochaete used in ecotoxicological studies.
abstract: BACKGROUND
  Earthworms are sensitive to toxic chemicals present in the soil and so are useful indicator organisms for soil health. Eisenia fetida are commonly used in ecotoxicological studies; therefore the assembly of a baseline transcriptome is important for subsequent analyses exploring the impact of toxin exposure on genome wide gene expression.
  
  
  RESULTS
  This paper reports on the de novo transcriptome assembly of E. fetida using Trinity, a freely available software tool. Trinotate was used to carry out functional annotation of the Trinity generated transcriptome file and the transdecoder generated peptide sequence file along with BLASTX, BLASTP and HMMER searches and were loaded into a Sqlite3 database. To identify differentially expressed transcripts; each of the original sequence files were aligned to the de novo assembled transcriptome using Bowtie and then RSEM was used to estimate expression values based on the alignment. EdgeR was used to calculate differential expression between the two conditions, with an FDR corrected P value cut off of 0.001, this returned six significantly differentially expressed genes. Initial BLASTX hits of these putative genes included hits with annelid ferritin and lysozyme proteins, as well as fungal NADH cytochrome b5 reductase and senescence associated proteins. At a cut off of P = 0.01 there were a further 26 differentially expressed genes.
  
  
  CONCLUSIONS
  These data have been made publicly available, and to our knowledge represent the most comprehensive available transcriptome for E. fetida assembled from RNA sequencing data. This provides important groundwork for subsequent ecotoxicogenomic studies exploring the impact of the environment on global gene expression in E. fetida and other earthworm species.
authors.affiliation: College of Health, Massey University, PO Box 756, Wellington, 6140, New Zealand. M.Thunders@massey.ac.nz.
authors.forename: Michelle
authors.identifier: http://orcid.org/0000-0001-6722-7072
authors.initials: M
authors.lastname: Thunders
authors.affiliation: Landcare Research, PO Box 40, Lincoln, 7640, New Zealand.
authors.forename: Jo
authors.initials: J
authors.lastname: Cavanagh
authors.affiliation: School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China.
authors.forename: Yinsheng
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D054750:Ecotoxicology; D004781:Environmental Exposure; D020869:Gene Expression Profiling / Q000379:methods*; D063990:Gene Ontology; D009835:Oligochaeta / Q000187:drug effects / Q000235:genetics*; D017423:Sequence Analysis, RNA / Q000379:methods; D012984:Software; D012989:Soil Pollutants / Q000633:toxicity; D043922:Toxicogenetics / Q000379:methods; D059467:Transcriptome
chemical_list: D012989:Soil Pollutants
keywords: E. fetida; Earthworm; Ecotoxicology; Gene expression; RNA; Sequence; Transcriptome; Trinity