Partial amino acid sequence and physiological effects of a 27 kDa parasitism-specific protein present in the plasma of parasitized Lacanobia oleracea (Noctuidae)

Abstract

Abstract. Parasitization of larvae of the tomato moth, Lacanonbia oleracea, by the ectoparasitic wasp, Eulophus pennicornis, results in the appearance of a 27 kDa parasitism-specific protein (PSP) in the plasma of the host. After isolation of this protein by native discontinuous polyacrylamide gel electrophoresis, whole gel elution and electroblotting, the N-terminal sequence of the 27 kDa PSP is determined by Edman degradation. The 20 amino acid residues obtained reveal 70% identity with a female-specific fat body protein from the moths Antheraea pernyi and Antheraea yamamai, 60% identity with a glutathione S-transferase (GST) isolated from Orthosia gothica, and a low level of identity with the N-termini of proteins belonging to the GST superfamily. Injection of the 27 kDa PSP into L. oleracea larvae has no significant effect on their ability to gain weight or the time at which they pupate. Furthermore, assays performed in vitro demonstrate that the 27 kDa PSP does not affect the ability of L. oleracea haemocytes to form aggregates. The precise source of the 27 kDa PSP remains unclear, although the current results suggest that it is most likely synthesized by host larvae in response to parasitism. The possible role(s) of the 27 kDa PSP are discussed with regard to the physiological effects of parasitism on the host.