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Title: Identification of a CAPA-PVK (Ixori-PVK/CAP2b) from single cells of the Gulf Coast tick, Amblyomma maculatum

item Strey, Allison
item Nachman, Ronald

Submitted to: Pestycydy/Pesticides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2007
Publication Date: 4/1/2008
Citation: Neupert, S., Russell, W.K., Russell, D.H., Strey, O., Teal, P., Strey, A.A., Nachman, R.J. 2008. Identification of a CAPA-PVK (Ixori-PVK/CAP2b) from single cells of the Gulf Coast tick, Amblyomma maculatum. Pestycydy/Pesticides. 1-2:67-73.

Interpretive Summary: Because of problems with the development of resistance to conventional pesticides, there is a critical need for new concepts and alternative approaches in controlling tick pests. The basic premise of this research is that neuropeptides (short chains of amino acids) serve as potent messengers in insects and ticks to regulate vital functions. New, selective control measures may be developed by designing metabolically stable mimics of these neuropeptides that actively inhibit or over-stimulate functions regulated by them, resulting in disruption of the internal environment of the insect or tick. We report on the use of state-of-the-art analytical techniques to unambiguously characterize the structure of a regulatory neuropeptide of a species of tick via direct analysis of a single organ. The subject of this investigation is the Gulf coast tick, a pest of livestock in the US. A deeper understanding of the specific structures of neuropeptides, where they are stored and released, and how these neuropeptides regulate critical processes in ticks will aid in the design of strategies to disrupt feeding and survival. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling pest ticks in an environmentally friendly fashion.

Technical Abstract: MALDI-TOF/TOF tandem mass spectrometry has been applied to determine the complete sequence of a CAPA-PVK in the gulf coast tick, Amblyomma maculatum. Single cell analysis allowed the identification of the amino acid sequence of Ixori-PVK (PALIPFPRV-NH2), a periviscerokinin which had previously been identified from two other ticks, Ixodes ricinus and Boophilus microplus. The identification indicates greater conservation of sequence for the PVK/CAP2b family in ticks as compared with insects. Side-chain fragmentation experiments provided data to distinguish between Leu/Ile ambiguities. The tick CAPA peptide shows a high sequence homology with other members of the insect periviscerokinin/CAP2b class of peptides, which are associated with the regulation of critical physiological processes such as diuresis. Thus, the identification of this neuropeptide will provide the experimental basis to better understand regulation of water balance in these arthropods, providing a potential opportunity to develop neuropeptide-based control strategies against these livestock pests.