The presence of peptides related to the adipokinetic hormone/red pigment-concentrating hormone family in the nematode, Panagrellus redivivus.

Immunocytochemistry using polyclonal antisera raised to fragments or derivatives of locust adipokinetic hormone (AKH) I and IIs (Schooneveld et al., 1983, 1985, 1986) selectively stained cells in the nervous system of the free-living nematode, Panagrellus redivivus. Antiserum 528 (raised to the C-terminus of AKH IIs) stained the dorsal cephalic papillary cell bodies and the anterior nerve ring. Fibres in the lateral cords were stained with antiserum 241 that recognises the C-terminus of AKH I. Substances reacting to antisera 433 (raised to the N-terminal sequence of AKH I and IIs) 528 and 241 were present in the preanal ganglion and associated ventral nerve fibres. In males, all three antisera stained fibres leading to the base of the spicules. A peptide fraction from whole P. redivivus evoked an adipokinetic response in the locust, Schistocera gregaria which was dose dependent and was abolished by treatment with endopeptidase 24:11 but not by boiling or by incubation with leucine aminopeptidase. The adipokinetic activity was reduced by over 70% on incubation of the peptide fraction with pyroglutamyl aminopeptidase. The same fraction induced hyperglycaemia when injected into the cockroach, Periplaneta americana. These results are consistent with the existence in P. redivivus of peptides that are structurally related to the arthropod adipokinetic hormone/red pigment-concentrating hormone (AKH/RPCH) family.