Exploring the Neuropeptides, Neuropeptide Receptors and Neurotransmitter Receptors in the Synganglia of Part-Fed Females of <i>Ornithodoros turicata</i> (Argasidae) and <i>Ixodes scapularis</i> (Ixodidae) with Insights Into Their Roles in Contrasting Biology

<p>The neurobiology of the synganglion (central nervous system) of the Lyme disease tick, <em>Ixodes scapularis</em> and the soft tick <em>Ornithodoros turicata</em> was evaluated using Illumina GAII high throughput sequencing which generated high coverage cDNA libraries (transcriptomes). These ticks exhibit different biological patterns of feeding, blood meal water, and salt elimination, cuticle plasticity versus cuticle synthesis, development and reproduction. RNA sequencing of <em>I. scapularis</em>, and <em>Ornithodoros turicata</em> yielded a total of 117,900,476 raw reads which were assembled to 30,838 contigs and a total of 63,528,102 also assembled to 132,258 contigs, respectively. Comparison of Gene Ontology (GO) mapping success for genes in 32 important GO molecular categories showed little difference between the two species.</p> <p>Functional assignments of transcripts predicting neuropeptides, neuropeptide receptors and neurotransmitter receptors was done, supported by strong e-values (< -6), and high consensus sequence alignments. For the synganglion of <em>I. scapularis</em>, transcripts predicting 23 neuropeptides and/or their receptors were identified. For the synganglion of <em>O. turicata</em>, 25 neuropeptides and/or their receptors were identified. Both species had transcripts predicting all of the same neuropeptides and/or their neuropeptide receptors in common except for allatotropin peptide, found only in I. scapularis, and allatostatin C, bursicon β, and glycoprotein B, which were found only in <em>O. turicata</em>.</p> <p>If the repertoire of neuropeptide and neurotransmitter messages expressed in the synganglia of <em>O. turicata</em> and <em>I scapularis </em>is so similar, how can we explain the very different physiological processes that occur in these two very different tick species? Real time PCR assays were used to study the expression of candidate genes in response to blood feeding. My study shows a strong similarity in gene identity (annotation/alignments) of both species but marked differences in the gene expression, extent of up-regulation or down-regulation, and the timing of their expression in response to feeding. This may indeed help explain many of the differences in the biology of the two different species. 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.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Year dc:date.available

2015

Author dc:creator

• Egekwu, Noble I.

Contributors dc:contributor

• Daniel E. Sonenshine
• David T. Gauthier
• Jing He
• Christopher Osgood
• R. Michael Roe

• Behavior
• Ixodid
• Neuropeptides
• RNA seq
• Ticks
• Transcriptomes
• Bioinformatics

Identifier

9781321839821

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:biomedicalsciences_etds-1030