The distribution and activity of tachykinin-related peptides in the blood-feeding bug, Rhodnius prolixus.
The invertebrate tachykinin-related peptides (TRPs) with the conserved C-terminal sequence FX1GX2Ramide shows sequence similarity to the vertebrate tachykinins after which they are named, and are hypothesized to be ancestrally related. In this study a polyclonal antiserum generated against a locust tachykinin (LomTK I), was used to demonstrate the presence and describe the distribution of LomTK-like immnoreactivity in the CNS and gut of Rhodnius prolixus. Reverse phase high performance liquid chromatography (RP-HPLC) was used in combination with a sensitive radioimmunoassay (RIA) to demonstrate picomolar amounts of immunoreactive material in the CNS, and femptomolar amounts associated with the hindgut. Furthermore, the results from CNS extracts separated by RP-HPLC, suggest that at least two tachykinin isoforms exist in R. prolixus. A hindgut contraction assay was developed to quantify the myotropic effects of selected LomTKs on R. prolixus hindgut contraction. Both LomTK I and II caused an increase in the frequency of hindgut contractions with EC50 values of 3.6x10(-8)M and 3.8x10(-8)M for LomTK I and II, respectively.
Kwok
Rodney
R
Department of Biology, University of Toronto at Mississauga, Mississauga, Ont., Canada, L5L 1C6. rodney.kwok@utoronto.ca
Chung
Doreen
D
Brugge
Victoria Te
VT
Orchard
Ian
I
D000818:Animals; D001921:Brain / Q000378:metabolism; D005724:Ganglia / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000378:metabolism; D007150:Immunohistochemistry; D007814:Larva / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism*; D012239:Rhodnius / Q000378:metabolism*; D015320:Tachykinins / Q000378:metabolism*
D010446:Peptide Fragments; D015320:Tachykinins