To adapt to different environmental conditions between poikilothermic and homeothermic hosts, the plerocercoid of Spirometra erinacei (sparganum) might express a variety of biologically active molecules. We have identified a 78 kDa glucose-regulated protein of the sparganum (SpGrp78) by differential display of mRNA, employing RNAs each from sparganum adjusted at 9 °C and 37 °C. A full-length cDNA of 2148 bp encodes for a protein of 651 amino acids with a predicted molecular mass of 71 610 Da and shares molecular characteristics with heat-shock protein 70, including a putative ATP binding site, signal peptide cleavage site and endoplasmic reticulum retention signal. Phylogenetic analysis revealed that SpGrp78 was mostly related to those of Echinococcus multilocularis and E. granulosus. Expression of SpGrp78 mRNA increased approximately 7-fold by inhibition of glycosylation by tunicamycin, 2-fold by temperature-shift from 9 °C to 37 °C and slightly by pH-shift to 4·0 or 5·5. These results suggested that induction of SpGrp78 mRNA is related to the functional role of SpGrp78 as a molecular chaperone when the parasite adapts to a new host environment.

The olfactory sensors of insects' antennae, which are directly exposed to the environment, play an important role in identifying volatile hydrophobic molecules in the air. As many odours in the air are cytotoxic xenobiotics, there must be mechanisms in insects' antennae to decompose the molecules and also redundant odorant stimulators. In the present study, differential display PCR was used to isolate three antenna-specific mRNAs from the moth of the cotton bollworm, Helicoverpa armigera. Sequence analysis of the A4-1 clone indicated that it was homologous to the glutathione-S-transferase (GST) protein family. Northern blotting showed that the A4-1 clone was expressed specifically in the antennae of H. armigera and the expressed level was higher in male antennae than in female ones; this is similar to the expression of PBP-Harm gene from cotton bollworm. According to the gene's expression in antennae and the role of GST reported in other insects, the gene is predicted to be responsible for the decomposition of pheromones and harmful xenobiotics in antennae.