Browsing by Author "Christina M. Grozinger, Committee Member"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • No Thumbnail Available
    The Genetic Architecture of odor-guided behavior in Drosophila melanogaster
    (2008-07-08) Sambandan, Deepa; Patricia A. Estes, Committee Member; Christina M. Grozinger, Committee Member; Trudy F.C. Mackay, Committee Co-Chair; Robert R. H. Anholt, Committee Chair
  • No Thumbnail Available
    Genomics of tick reproduction and development
    (2008-12-02) Donohue, Kevin Vincent; Daniel E. Sonenshine, Committee Member; R. Michael Roe, Committee Chair; Christina M. Grozinger, Committee Member; Charles S. Apperson, Committee Member
    The major hemelipoglyco-carrier protein (CP) found throughout the development of male and female adult American dog ticks, Dermacentor variabilis (Say) was sequenced. DvCP is a single transcript coding for two protein subunits that together contain three motifs—(a) a lipoprotein n-terminal domain that is a common attribute of proteins that bind lipids, carbohydrates and metals, (b) a domain of unknown function characteristic of proteins with several large open beta sheets and (c) a von Willebrand factor type D domain near the carboxy-terminus apparently important for multimerization. These motifs also found in tick vitellogenin are not shared by heme-binding proteins studied thus far in other hematophagous insects. DvCP message was highest in fat body and salivary gland but was also found in midgut and ovary. Expression was initiated by blood feeding in virgin females and not by mating typical of tick vitellogenin (Vg); and the message was found in fed males at levels similar to part fed, virgin females. CP appears to be highly conserved among the Ixodida and shares a common origin with Vg. In the second part of this study, the tick synganglion transcriptome was studied by pyrosequencing to identify neuropeptides that regulated reproduction and development. Greater than 500,000 reads were assembled into 21,119 contiguous sequences of which 10,674 could be putatively identified. Twelve putative neuropeptides and five neuropeptide receptors from the synganglion of D. variabilis were selected for further study. Many of these neuropeptides such as an allatostatin, insulin-like peptide, eclosion hormone, bursicon alpha and beta and glycoprotein hormone alpha and beta have not been previously described in the Chelicerata. An insulin receptor substrate protein was also found indicating that at insulin signaling network is present in ticks. A putative type-2 proprotein processing convertase was sequenced that may be involved in cleavage at monobasic and dibasic endoproteolytic cleavage sites in prohormone peptides. Synganglion specific quantitative real-time PCR data were obtained for all of the putative neuropeptides, neuropeptide receptors and proprotein processing convertase in order to gain an initial understanding of their role in the synganglion during adult tick blood feeding and reproduction.
  • No Thumbnail Available
    Novel Methods of Hematophagous Arthropod Control
    (2009-11-24) Bissinger, Brooke Witting; D. Wesley Watson, Committee Member; Christina M. Grozinger, Committee Member; Charles S. Apperson, Committee Member; James Harper, Committee Member; R. Michael Roe, Committee Chair
    Ticks are important vectors of human and animal diseases. One protective measure against ticks is the use of personal arthropod repellents. Here, the history and efficacy of tick repellents, discovery of new repellents, and areas in need of attention such as assay methodology, repellent formulation, and the lack of information about the physiology of repellency are reviewed. Studies were conducted to examine the efficacy of the repellent BioUD with the active ingredient 7.75% 2-undecanone, originally derived from wild tomato plants. BioUD was compared with 7 and 15% deet using arm-in-cage studies against the mosquitoes Aedes aegypti and Ae. albopictus. No differences were found in mean repellency over 6 h after application between BioUD versus 7 and 15% deet for Ae albopictus. For Ae. aegypti, no differences were found over the same time period for 7% deet. Compared to 15% deet, BioUD was less repellent over the 6-h test period. Human subject field trials were conducted in North Carolina and Ontario comparing the repellency of BioUD to products containing 25 and 30% deet. BioUD provided the same repellency or was more efficacious than 25 and 30% deet, respectively. Repellent efficacy of BioUD and 98.1% deet against ticks was examined in the laboratory using a choice test between repellent-treated and control filter paper surfaces for Amblyomma americanum, Dermacentor variabilis and Ixodes scapularis. BioUD provided greater repellency against A. americanum and I. scapularis than deet. No difference was found between BioUD and deet against D. variabilis. In head-to-head assays between BioUD and deet, undiluted and 50% dilutions of BioUD were more repellent than undiluted deet against all three species. A 25% dilution of BioUD was more repellent than deet against A. americanum while no differences were found between a 25% dilution of BioUD and deet against D. variabilis and I. scapularis. Based on regression analysis, the concentration of BioUD required for equivalent repellency to 98.1% deet was 39.5% for D. variabilis and 29.7% for I. scapularis. A log-probit model could not be constructed for A. americanum from the dosages tested. Repellency of BioUD was compared to five repellents against A. americanum and D. variabilis in two-choice bioassays on treated versus untreated cotton cheesecloth. Overall mean percentage repellency against both species was greatest for and did not differ significantly between BioUD and products containing 98.1% deet, 19.6% IR3535, and 30% oil of lemon eucalyptus. Products containing 5 and 15% Picaridin and 0.5% permethrin were also repellent compared to untreated controls but to a lesser degree than BioUD. The four most active repellents were directly compared in head-to-head bioassays. BioUD provided significantly greater overall mean percentage repellency than IR3535 for A. americanum and D. variabilis. BioUD was significantly more repellent than oil of lemon eucalyptus for A. americanum but did not differ significantly in repellency against D. variabilis. No statistically significant difference in overall mean percentage repellency was found between BioUD and deet for A. americanum or D. variabilis. Laboratory trials were also conducted to determine the repellent activity of BioUD against D. variabilis on human skin. BioUD repelled ticks at least 2.5 h after application to human skin. Characterization of the expressed genes in the tick central nervous system could lead to a greater understanding of the control of development and reproduction at the molecular level. A transcriptome to the female D. variabilis synganglion identified 21,119 unique putative gene sequences, of which 7,379 had significant matches to the GenBank nonredundant database. Microarray analysis comparing synganglia from unfed, partially fed, and mated replete females revealed that 121 of these genes were differentially regulated.