THE DETECTION OF AKH HRTH-LIKE PEPTIDES IN ASCARIDIA-GALLI AND ASCARIS-SUUM USING AN INSECT HYPERGLYCEMIC BIOASSAY/

Evidence for the presence of adipokinetic hormone/hypertrehalosaemic h ormone (AKH/HrTH)-like peptides in the parasitic nematodes Ascaridia g alli and Ascaris suum has been obtained using insect bioassays which m easure hyperglycaemic responses to peptides belonging to the AKH/HrTH family of insect hormones. A peptide fraction extracted from heads and tails of Ascaridia galli evoked a dose-dependent hyperglycaemic respo nse when injected into the cockroach, Periplaneta americana. Maximal b ioactivity was obtained with material that was equivalent to 38 mg (we t weight) of nematode. Bioactivity appeared to be highest in extracts from heads and tails of both male and female worms and could be fracti onated into at least three peaks of hyperglycaemic activity by reverse d-phase high-performance liquid chromatography. An extract from heads and tails of A. suum also evoked a hyperglycaemic response when inject ed into the cockroach, Blaberus discoidalis. The bioactivity was inact ivated on incubation with pure endopeptidase 24.11, confirming the pep tidic nature of the bioactive material. These results provide evidence for the existence of peptides related to the insect AKH/HrTH family o f peptides in parasitic nematodes.