Exposure to microwave radiation enhances the aggregation of bovine serum albumin in vitro in a time-and temperature-dependent manner. Microwave radiation also promotes amyloid ¢bril formation by bovine insulin at 60 ‡C. These alterations in protein conformation are not accompanied by measurable temperature changes, consistent with estimates from ¢eld modelling of the speci¢c absorbed radiation (15^20 mW kg 31 ). Limited denaturation of cellular proteins could explain our previous observation that modest heat-shock responses are induced by microwave exposure in Caenorhabditis elegans. We also show that heat-shock responses both to heat and microwaves are suppressed after RNA interference ablating heat-shock factor function. ß

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Transgenic strains of the nematode Caenorhabditiselegans, which carry stress-inducible lacZ reporter genes, aremeasurably stressed by exposure to heavy metals in aqueous solution. Thisstress response can be quantified, using enzymatic assays for the reportergene-product (Escherichia coli beta-galactosidase), or estimatedapproximately by in situ staining for beta-galactosidase in exposedworms. Stress responses to heavy metals have been demonstrated both inlaboratory tests using Cd2+ or Hg2+, and also in watersamples taken from a metal-polluted river system in southwest England. TheRiver Carnon flows through an area with an ancient mining history,principally for Sn, but also for Cu and other metals; As, Cd, Al, Mn, and Zn,as well as large amounts of Fe, are all present in these ore bodies. Foursites in the Carnon river basin were compared with respect to theirmacroinvertebrate diversity, physical and chemical characteristics (includingthe concentrations of As, Cd, Al, Cu, Mn, Zn, and Fe). Transgenic worms wereexposed to water samples from these four sites, and also to a 0.33%(v/v) dilution of metal-laden minewater from the principal local mine (WhealJane). Transgene expression was induced in all five cases, though markedlyless so for the least polluted of the sites (which also supported a richermacroinvertebrate fauna). Two different transgenic strains were tested inthis study; strain PC72 (using a homologous hsp16 promoter) isslightly more sensitive to most metal-containing water samples than strainCB4027 (using a heterologous Drosophila hsp70 promoter). Bothtransgenic strains and two different assay methods gave essentially similarresults. These findings demonstrate that transgenic nematodes could provide arapid and simple assessment of aquatic pollution, in that the transgeneresponse is inducible by mixtures of dissolved metals at concentrationsactually encountered in metal-polluted watercourses.

A toxicity test using a transgenic strain of the free-living soil nematode Caenorhabditis elegans carrying a stress-inducible beta-galactosidase reporter has been adapted for use in soil biomonitoring. High concentrations (250 microg. g(-1)) of cadmium are required to induce the stress response in worms exposed to Lufa 2.2 soil. Even at relatively high concentrations, the response to copper and zinc additions alone is minimal, yet combinations of cadmium and copper in the test soil induce a larger response than with cadmium alone at the same concentration. In contrast, the addition of both zinc and cadmium induces a lower response than cadmium additions alone. Analysis of the interstitial water suggests that there is preferential occupation by copper of sorption sites in the soil, allowing more cadmium to remain in solution. Conversely, cadmium and zinc would appear to interact similarly with the soil constituents, resulting in an increase of both metals in solution with increased additions to the soil. Aquatic tests mimic the results of the soil test, so it is not increased cadmium availability alone that causes an increased stress response when both cadmium and copper are present. The presence of other metals could reduce the amount of cadmium available, which may be one factor in the zinc moderation of the stress response to cadmium. Intracellular mechanisms may also contribute to the copper enhancement of the stress response to cadmium.http://link. springer-ny.com/link/service/journals/00244/bibs/37n4p503.++ +html

The neural protein α-synuclein aggregates both in vivo and in vitro to form insoluble fibrils that are involved in Parkinson’s disease pathogenesis. We have generated α-synuclein/fluorescent-protein fusion constructs overexpressed in muscle cells of the nematode, Caenorhabdtis elegans. Green Fluorescent Protein (GFP) variants, Cerulean (C) or Venus (V), were fused to the C-terminus of human α-synuclein (S); the resultant fusion genes were designated SV and SC, plus a CV fusion as well as S, C and V singly. The aggregation behavior of the purified fusion proteins (expressed in E. coli) will be described elsewhere. These constructs were fused to a C. elegans unc-54 myosin promoter, and integrated transgenic lines generated by microinjection, γ-irradiation, and outcrossing of fluorescent progeny. All transgenic lines expressing α-synuclein showed significant reductions (p < 0.05) in lifespan, motility and pharyngeal pumping, as compared to wild-type worms or lines expressing CFP and/or YFP only. We showed that CFP and YFP labels colocalised in granular inclusions throughout the body wall in transgenic lines expressing both SC and SV fusions (SC+SV), whereas SV+C worms displayed YFP-labelled inclusions on a diffuse CFP background. These findings implied that the α-synuclein moieties of these fusion proteins still aggregated together in vivo, whereas CFP or YFP moieties alone did not. This in turn suggested that Foerster Resonanace Energy Transfer (FRET) between CFP and YFP labels in α-synuclein aggregates could allow the extent of aggregation to be quantified. Accordingly, we also showed that net FRET signals increased 2-fold between L4 and adult SC+SV worms.

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