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Abstract
The effects of UV irradiation on infection of nematodes by two nematode-trapping fungi were studied. Five minutes UV irradiation of the fungi caused an inhibition of the infection process in both Arthrobotrys oligospora and Dactylaria candida. After the nematodes were captured, the infection process stopped; the nematodes were still moving at a time when the nematodes in untreated controls were completely digested. The UV-irradiated fungi were still alive and were capable of further growth. After 15 min UV irradiation the number of captured nematodes was also reduced. Inhibition studies with cycloheximide showed differences between the two fungi. The nematodes were still alive 24 h after capture by treated cultures of A. oligospora while the infection process was normally completed by D. candida. There were minor differences in the peptide pattern on a SDS-PAGE gel between proteins from untreated and UV-irradiated mycelia of both fungi. Both the results from inhibition experiments and changes in the peptide pattern after UV irradiation suggest that the target molecules affected by UV irradiation may have been proteins involved in the infection process, and not the DNA. No effect of UV irradiation was observed on molecules that had been suggested previously to be involved in the nematode infection process (toxins, lectins and proteases).
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