Whole body transcriptomes of the tick Ixodes ricinus in different stage and feeding conditions

While several transcriptomic studies of ticks during feeding have focused on salivary glands (but also midguts and haematocytes), no study using high throughput sequencing has concerned the whole tick body for Ixodes ricinus. We chose to analyse changes of expression level at the whole body level to obtain a more general description of expression changes (comparing unfed and partially fed ticks).Ticks (Ixodes ricinus) from a lab strain (Neuchâtel), reared since 1980, were used for an expression study where we compared different stages (nymphs, adults), sexes (females, males) and feeding conditions (unfed, partially fed). Nymphs were fed on mice (Mus musculus) and removed after24 hours of attachment while adults females were fed on rabbits (Oryctolagus cuniculus) andremoved after 48 hours. There were three replicates for each condition (biological replicates). RNA was extracted from whole bodies (numbers of individuals vary between conditions) with a Trizol protocol, using two DNAses treatments. Libraries were prepared using the Truseq Stranded kit (v4), and were sequenced on one lane of the Illumina HiSeq 2500 (oriented PE sequencing, 2x125bp reads).We obtained a total of 120,633,827 clusters. The raw reads were cleaned (quality filters, elimination of reads matching rRNA, elimination of orphans) and assembled with Trinity into 179,682 contigs. These contigs were annotated (Trinotate). We performed a differential expression study to compare conditions (with GO-enrichment tests), and assessed polymorphism levels.