Specific differential expression of elongation factor 1a, which binds t-RNA to ribosomes, and of 40S ribosomal protein S9 are indicative of increased protein translation in resistant snail haemocytes in general. On the other hand, differential expression of cathepsins D and L, intracellular lysosomal aspartic and cysteine proteinases respectively, by susceptible snail haemocytes in the presence of ESPs suggests an increased capacity to degrade protein, including that released by the parasite and internalized by the haemocyte. Because a cathepsin L-like protease precursor gene was found to be upregulated in resistant B. glabrata 2/24 h after snails were exposed to S. mansoni, it seems that intracellular haemocyte protease expression in response to S. mansoni is complex and might depend on the nature of the stimulus and the duration of exposure. Twenty-four genes that displayed differential expression after 1 h ESP exposure and were unique to this study are of unknown function. It is anticipated that advances in functional genomics in snails, including gene knockdown with RNA interference to determine the function of some of these genes, will be critical in furthering our understanding of ESP-specific effects on haemocyte functional biology. In our recently published work 417 genes were differentially expressed in B. glabrata haemocytes following 2 h exposure to S. mansoni in vivo. Therefore, as might be expected, the physical presence of the schistosome, possibly with its ciliated epidermal plates, appears to influence haemocyte gene expression profoundly, beyond that seen in response to ESPs alone. Genes for the molecular chaperone heat shock protein 70 have been found in many studies to be differentially expressed in S. mansoniresistant snails in response to S. mansoni infection, while in others they have been shown to be upregulated in the susceptible strain. Given that HSP70 is a stress response protein that is activated rapidly by a plethora of potentially harmful stimuli it is perhaps surprising that when exposed to ESPs haemocytes from the different snail strains did not reveal differential HSP70 gene expression. When exposed to 20 mg/ml ESPs for 1 h, haemocyte HSP70 protein levels are significantly reduced in the same snail strains as those used in the current study partly through degradation by the proteasome, but recover only in the susceptible strain after 5 h. A possibility in the current study is that certain genes including HSP70 are constitutively expressed in the resistant strain more than in the susceptible, and that ESP dependent changes result in a situation where the mRNA levels become PCI-32765 purchase indistinguishable, masking any effect. However, in our recent analysis, constitutive expression of HSP70 did not differ between the same snail strains. Recently, HSPs were shown to play a role in B. glabrata resistance to S. mansoni, as exposing resistant B. glabrata to increased temperature for 4 h prior to S. mansoni infection resulted in a phenotype switch whereby the resistant snails became susceptible to the parasite.