Student Theses and Dissertations

Jeff Liesch

Date of Award

2014

Document Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

RU Laboratory

Vosshall Laboratory

Abstract

Aedes aegypti mosquitoes are the principal vectors for several human diseases including Dengue Fever, which causes ~400 million cases and ~24,000 deaths per year (Bhatt et al., 2013; WHO, 2002). Novel strategies to combat mosquito-borne diseases are needed for A. aegypti and other mosquitoes such as the malaria vector Anopheles gambiae. Our goal was to discover new ways to interfere with the ability of a mosquito to locate a human host for a blood meal. Currently, the mechanistic basis of host-seeking and its regulation remain incompletely understood. Although it is known that mosquitoes require human odor cues to locate a human host, the critical odor components and associated olfactory receptors have not been identified (Klowden, 1995; Takken and Knols, 1999). Previous work showed that mosquito host-seeking behavior is inhibited by a hemolymph-borne humoral factor for three days following a blood meal. Subsequent studies identified Head Peptide-I as a candidate neuropeptide modulating this suppression in host-seeking behavior. This conclusion was strengthened by the observation that Head Peptide-I injection into non-blood-fed females triggered the inhibition of host-seeking. The mechanism by which this important peptide alters mosquito behavior and the receptor through which it signals are unknown (Brown et al., 1994). We used a cell-based calcium-imaging screen to identify the G-protein coupled receptor NPY-Like Receptor-1 (NPYLR1) as a candidate Head Peptide-I receptor. We found that multiple NPYLR1 agonists, including the feeding-related Short-Neuropeptide-3 (sNPF3), are capable of inhibiting host-seeking behavior when injected into non-blood-fed females. To investigate whether NPYLR1 is required for Head Peptide-I inhibition, we pioneered targeted mutagenesis with zinc-finger nucleases to create multiple NPYLR1 null-mutant mosquito lines. We predicted that these mutants would no longer show inhibition of host-seeking behavior after a blood meal. While we can say with certainty that NPYLR1 is a receptor for Head Peptide-I, we found no behavioral effects for NPYLR1 mutants in locomotion, egg-laying, sugar feeding, blood feeding, or host-seeking behavior. Our results suggest that NPYLR1 is not required in vivo for Head Peptide-I action and that a redundant signaling mechanism for behavioral inhibition exists. Future work will determine the necessity of Head Peptide-I during host-seeking inhibition and attempt to identify additional Head Peptide-I and sNPF receptors. This research will clarify the mechanism of Head Peptide-I inhibition and could form the basis for novel strategies to control mosquito host-seeking behavior.

Comments

A Thesis Presented to the Faculty of The Rockefeller University in Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy

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