Transgenic stress-inducible strains of Caenorhabditis elegans have been evaluated in biomonitoring applications. Two transgenic lacZ-reporter strains have been utilised:- strain CB4027 (heterologous Drosophila
hsp70 promoter) and strain PC72 (homologous hsp 16 promoter). The stress response in exposed worms is detectable by in situ staining for ss-galactosidase, and can be quantified using enzymatic assays. Stress responses to heavy metals have been demonstrated in laboratory tests and in water samples taken from a metal-polluted river system in south-west England. Surfactants amplify the effects of most metal ions tested. This biomonitoring test is being adapted for use in soils with the PC72 strain. In LUFA 2.2 soil, the stress response to Cd2+ and Hg2+ is proportional to their concentrations in centrifugally extracted soil water, which are much less than those originally added because of metal sorption to soil constituents. Immunological stress responses are also being evaluated in strain PC72 as a model for the effects of immune responses on parasitic nematodes. Antiserum raised against CTAB-stripped surface antigens gave specific surface labelling of worms. Although this antiserum evoked a significant stress response in PC72 worms, so too did naive rabbit serum. Specific immuno-fluorescence tests using naive rabbit serum and FITC-conjugated anti-C3 antibody suggest that the surface of C.elegans is itself capable of fixing complement, which may mediate a stress response. Future work will involve the development of novel hsp/GFP fusion strains to enable continuous dynamic monitoring of transgene product levels. This will necessitate the use of GFP variants in order to reduce the interference from gut autofluorescence.