The detection of AKH/HrTH-like peptides inAscaridia galliandAscaris suumusing an insect hyperglycaemic bioassay

Abstract

SUMMARYEvidence for the presence of adipokinetic hormone/hypertrehalosaemic hormone (AKH/HrTH)-like peptides in the parasitic nematodesAscaridia galliandAscaris suumhas been obtained using insect bioassays which measure hyperglycaemic responses to peptides belonging to the AKH/HrTH family of insect hormones. A peptide fraction extracted from heads and tails ofAscaridia gallievoked a dose-dependent hyperglycaemic response when injected into the cockroach,Periplaneta americana. Maximal bioactivity was obtained with material that was equivalent to 38 mg (wet weight) of nematode. Bioactivity appeared to be highest in extracts from heads and tails of both male and female worms and could be fractionated into at least three peaks of hyperglycaemic activity by reversed-phase high-performance liquid chromatography. An extract from heads and tails ofA. suumalso evoked a hyperglycaemic response when injected into the cockroach,Blaberus discoidalis. The bioactivity was inactivated on incubation with pure endopeptidase 24.11, confirming the peptidic nature of the bioactive material. These results provide evidence for the existence of peptides related to the insect AKH/HrTH family of peptides in parasitic nematodes.