Neuropeptide signaling sequences identified by pyrosequencing of the American dog tick synganglion transcriptome during blood feeding and reproduction Kevin V. Donohue a , Sayed M.S. Khalil a,1 , E. Ross b , Christina M. Grozinger a, 2 , Daniel E. Sonenshine b , R. Michael Roe a, * a Department of Entomology, Campus Box 7647, North Carolina State University, Raleigh, NC 27695-7647, USA b Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529, USA article info Article history: Received 3 December 2008 Received in revised form 18 December 2009 Accepted 21 December 2009 Keywords: Ticks Reproduction Blood feeding Synganglion Allatostatin Insulin-like peptide Ion-transport peptide Sulfakinin Bursicon alpha Bursicon beta Eclosion hormone Glycoprotein hormone alpha Glycoprotein hormone beta Corazonin Orcokinin Gonadotropin receptor Leucokinin-like receptor Sulfakinin receptor Calcitonin receptor Pyrokinin receptor Pyrosequencing abstract Ticks are important vectors of numerous pathogens that impact human and animal health. The tick central nervous system represents an understudied area in tick biology and no tick synganglion-specific transcriptome has been described to date. Here we characterize whole or partial cDNA sequences of fourteen putative neuropeptides (allatostatin, insulin-like peptide, ion-transport peptide, sulfakinin, bursicon alpha/beta, eclosion hormone, glycoprotein hormone alpha/beta, corazonin, four orcokinins) and five neuropeptide receptors (gonadotropin receptor, leucokinin-like receptor, sulfakinin receptor, calcitonin receptor, pyrokinin receptor) translated from cDNA synthesized from the synganglion of unfed, partially fed and replete female American dog ticks, Dermacentor variabilis. Their homology to the same neuropeptides in other taxa is discussed. 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 an insulin signaling network is present in ticks. A putative type-2 proprotein processing convertase was also sequenced that may be involved in cleavage at monobasic and dibasic endopro- teolytic cleavage sites in prohormones. The possible physiological role of the proteins discovered in adult tick blood feeding and reproduction will be discussed. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Ticks are obligate ectoparasites that vector the greatest variety of pathogens of any blood-feeding arthropod (Sonenshine, 1993). Development of precisely targeted tick control strategies could be ameliorated by a better understanding of the basic physiology of these organisms. The processes that control tick feeding and reproduction represent obvious targets for developing such a strategy. However, only recently have the major yolk proteins been fully sequenced, and only a few species have been studied (Thompson et al., 2007; Mitchell et al., 2007). Furthermore, other recent studies on vitellogenesis in ticks indicate that a consensus model of tick reproduction will require studies from multiple taxa in order to understand key regulatory differences (Seixas et al., 2008). Blood feeding and mating are necessary requirements for the development of viable eggs in ticks. However, the timing of blood * Corresponding author. Tel./fax: þ1 919 515 4325. E-mail address: michael_roe@ncsu.edu (R. Michael Roe). 1 Current address: Agricultural Genetic Engineering Research Institute (AGERI), Agricultural Research Center, 9 Gamma Street, Giza, Egypt. 2 Current address: Department of Entomology, Center for Chemical Ecology, Huck Institutes of the Life Sciences, Pennsylvania State University, Chemical Ecology Lab 4A, University Park, PA 16802, USA. Contents lists available at ScienceDirect Insect Biochemistry and Molecular Biology journal homepage: www.elsevier.com/locate/ibmb 0965-1748/$ e see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ibmb.2009.12.014 Insect Biochemistry and Molecular Biology 40 (2010) 79e90