Submitted to: Neurochemical Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 28, 1997
Publication Date: N/A
Interpretive Summary: Ongoing efforts to find new and improved methods for controlling blood feeding insects such as mosquitoes are focusing on development of a new generation of pesticides that act by disrupting functions of neuropeptides. Neuropeptides are short chains of amino acids (the building blocks of proteins) and are essential in regulating vital life processes of these insects. Three phases are required in this research: 1) isolate, identify and synthesize the neuropeptides; 2) determine tissue localization and function of each peptide; and 3) prepare synthetic insecticidal agents that mimic the activity of the natural peptide. The first two phases of this process have been completed in the isolation, identification and localization of 3 new neuropeptides of the salt marsh mosquito, Culex salinarius. This is an important agricultural pest because in some regions populations of this species often increase to such numbers that their feeding on cattle results in major blood loss that seriously weaken or kil the animals. The new peptides isolated from C. salinarius were found to be produced in the brain, other nerve tissue, and in nerve cells of the antennae. The latter is significant since the antennae are used by female mosquitoes to locate host animals and by males to locate females for mating. This is the first time antennal neuropeptides have been found in a pest species of insect and may provide the means of developing a species specific pesticide.
Three myotropic peptides belonging to the Arg-amide insect tachykinin family were isolated from whole-body extracts of the mosquito, Culex salinarius. The peptides, APSGFMGMR-NH2, APYGFTGMR-NH2 and APSGFFGMR-NH2 (designated culetachykinin, I, II and III) were isolated and purified on the basis of their ability to stimulate muscle contractions of isolated Leucophaea maderae hindgut. Biologically inactive methionine sulfoxides o two of the three peptides were isolated using an ELISA system based upon antiserum raised against APYGFTGMR-NH2 and identified with mass spectrometry. Immunocytochemistry localized these peptides in cells in the brain, antennae, subesophageal, thoracic and abdominal ganglion, proventriculus and midgut. Nerve tracts containing these peptides were found in the median nerve of the brain, central body, nervi corpus cardiaci, cervical nerve, antennal lobe and on the surface of the midgut.