Fibronectin-binding proteins of Clostridium perfringens recognize the III1-C fragment of fibronectin.

The Clostridium perfringens strain 13 genome contains two genes (fbpA, fbpB) that encode putative Fbp. Both rFbpA and rFbpB were purified and their reactivity with human serum Fn was analyzed. To determine the region of the Fn molecule recognized by rFbp, a plate binding assay using N-terminal 70-kDa peptide, III1-C peptide, and 110-kDa peptide containing III2-10 of Fn was performed. Both rFbp bound to the III1-C peptide of Fn but not to the other peptides. However, the III1-C fragment of Fn is known to be cryptic in serum Fn. Then, rFbp-BP from Fn were purified by rFbp-affinity chromatography. The yield of purified proteins was approximately 1% of the applied Fn on a protein basis. Western blotting analysis of the rFbp-BP, using four different anti-Fn monoclonal antibodies, revealed that the rFbp-BP carried partial Fn antigenicity. Bindings of rFbp to rFbp-BP were inhibited by the presence of the III1-C peptide, suggesting that rFbp-BP express the III1-C fragment. The binding of Fn to III1-C was inhibited by the presence of either rFbpA or rFbpB. This result that suggests C. perfringens Fbps may inhibit the formation of Fn-matrix in vivo.

Toxicity reduction of metal pyrithiones by near ultraviolet irradiation.

Zinc pyrithione (ZnPT) or copper pyrithione (CuPT) have been effectively used as ship-antifouling agents, as an alternative to organotin compounds. Because of their instability in light and a lack of suitable analytical procedures, there is little data on their residue levels in environmental matrices. It is possible to investigate the fate of such compounds by toxicity alteration with certain treatments. The purpose of this study was to evaluate the degradation of pyrithiones through toxicity reduction by near ultraviolet (UV-A) irradiation. Metal pyrithiones dissolved in acetonitrile were irradiated with a UV-A lamp for 0, 0.5, 1, and 2 h, and were subjected to UV spectral measurement and toxicity evaluation using both sea urchin and freshwater rotifer bioassays. For the bioassays, photolyzed samples were dissolved in dimethyl sulfoxide after evaporation of the acetonitrile. The changes in UV spectra of photolyzed ZnPT or CuPT showed a time-dependent degradation, and the UV spectra at 2 h irradiation suggested substantial decomposition. Toxicities of ZnPT and CuPT were 12 and 5 microg/L as 24 h LC50 to the survival of rotifers and 10(-6) ng/L and 2.3 ng/L as 27 h EC50 to normal pluteus formation, respectively. By evaporation of the acetonitrile, the EC50 of ZnPT was 2.2 ng/L, which was the same as that of CuPT. The EC50s of ZnPT or CuPT for both species increased with longer irradiation times. Photolyzed ZnPT or CuPT demonstrated substantial degradation in the UV spectra, but possessed marked toxicity, which is probably due to toxic degradation products. One reason why photolyzed CuPT was toxic to rotifers was explained by the high toxicity of copper ions formed by UV-A irradiation.