Comparative transcriptomics: Using high-through put sequencing technology to explore biology and behavior of an ixodid Ixodes scapularis and an argasid Ornithodoros turicata

The neurobiology of the synganglion (central nervous system) of the Lyme disease tick, Ixodes scapularis and the soft tick Ornithodoros turicata was evaluated using Illumina GAII high throughput sequencing which generated high coverage cDNA libraries (transcriptomes).  These ticks exhibit very biological patterns of feeding, blood meal water and salt elimination, cuticle plasticity versus cuticle synthesis, development and reproduction.  For I. scapularis, sequencing yielded a total of 117,900,476 raw reads which were assembled to 30,838 contigs.  For O. turicata, sequencing yielded a total of 63,528,102 which were assembled to 132,258 contigs.  Comparison of Gene Ontology (GO) mapping success for genes in 32 of the most important GO molecular categories showed relatively little difference between the two species (t = 0.277, P < 0.05, NS).  If the repertoire of neuropeptide and neurotransmitter messages expressed in the synganglia of O. turicata and I. scapularis is so similar, how can we explain the very different physiological processes that occur in these two very different tick species?  Quantitative PCR was used to study gene expression patterns in the two tick species.  Our findings indeed are intteresting.  The diversity of messages predicting important genes identified in this study and differences in their expression in response to feeding offers a valuable resource useful for understanding how the tick synganglion regulates important physiological functions in ticks