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The skin sensitization potential of agrochemicals can be assessed using laboratory methods such as the keratinocyte activation assay so that their use in regulatory toxicology might replace experimental animal testing. Here, we evaluated the skin sensitization potential of 11 agrochemicals by using an antioxidant response element–nuclear factor erythroid 2 luciferase assay in KeratinoSens and LuSens cells and applying a skin sensitization adverse outcome pathway (AOP). The KeratinoSens and LuSens assays consistently evaluated the skin sensitization potential of 10/11 agrochemicals with reference to animal testing databases. Benomyl, pretilachlor, fluazinam, terbufos, butachlor, and carbosulfan were correctly detected as sensitizers, and glufosinate ammonium, oxiadiazon, tebuconazole, and etofenprox were correctly detected as non-sensitizers. For diazinon, the skin sensitizing potential was positive in the KeratinoSens assay but not in the LuSens assay. These results suggest that the evaluation of in vitro skin sensitization using the AOP mechanism can be applied to assess active agrochemicals. [ABSTRACT FROM AUTHOR]

Chromobacterium sp. strain C61 has strong biocontrol activity; however, the genetic and biochemical determinants of its plant disease suppression activity are not well understood. Here, we report the identification and characterization of two new determinants of its biocontrol activity. Transposon mutagenesis was used to identify mutants that were deficient in fungal suppression. One of these mutants had an insertion in a homologue of depD, a structural gene in the dep operon, that encodes a protein involved in non-ribosomal peptide synthesis. In the second mutant, the insertion was in a homologue of the luxI gene, which encodes a homoserine lactone synthase. The luxI- and depD- mutants had no antifungal activity in vitro and a dramatically reduced capacity to suppress various plant diseases in planta. Antifungal production and biocontrol were restored by complementation of the luxI- mutant. Other phenotypes associated with effective biological control, including motility and lytic enzyme secretion, were also affected by the luxI mutation. Biochemical analysis of ethyl acetate extracts of culture filtrates of the mutant and wild-type strains showed that a key antifungal compound, chromobactomycin, was produced by wild-type C61 and the complemented luxI- mutant, but not by the luxI- or depD- mutant. These data suggest that multiple biocontrol-related phenotypes are regulated by homoserine lactones in C61. Thus, quorum sensing plays an essential role in the biological control potential of diverse bacterial lineages. [ABSTRACT FROM AUTHOR]

Biosurfactants have been used for crop protection in integrated pest management programs, as they are generally biodegradable and environmentally friendly. While screening for insecticidal bacteria against green peach aphid, Myzus persicae, we found that a Bacillus isolate, Y9, exhibited strong surface tension activity and produced insecticidal metabolites. The insecticidal metabolites with surface tension activity were extracted from the cell-free supernatant of Y9 and subjected to repetitive column chromatography and preparative high performance liquid chromatography (HPLC). Based on data from instrumental analyses, the metabolites were identified as surfactin isomers consisting of C14[Leu7], C14[Val7] and C15[Leu7]. The isomers with leucine showed higher insecticidal activity than the isomers with valine. Y9 was capable of producing biosurfactants as insecticidal metabolites against M. persicae, and showed potential for use as a biocontrol agent in an integrated pest management program. [ABSTRACT FROM AUTHOR]

Chromobacterium sp. strain C61 displays antifungal activities in vitro and has been used successfully for the biocontrol of plant diseases under field conditions. In this study, the roles of extracellular chitinase and an antifungal compound produced by strain C61 were investigated to elucidate their contributions to biological control activity. The bacterium possessed a locus chi54 encoding an extracellular chitinase, and mutation of chi54 eliminated chitinase production. Production of the extracellular enzyme and expression of the chi54 transcript were increased in the wild-type strain when chitin was added to the culture medium. In vitro assays showed that purified chitinase inhibited spore germination of multiple pathogens. However, the in planta biocontrol activity of filtrates of cultures grown in the presence of chitin was lower than that of filtrates grown without chitin, indicating that correlation between chitinase and biocontrol activity was lacking. The analysis of C61 culture filtrates revealed an antifungal cyclic lipopeptide, chromobactomycin, whose structure contained a unique nonameric peptide ring. The purified chromobactomycin inhibited the growth of several phytopathogenic fungi in vitro, and plant application significantly reduced disease severity for several pathogens. Furthermore, the production of chromobactomycin was reduced in cultures amended with chitin. These data suggest that the production of both the extracellular chitinase Chi54 and the newly identified antibiotic chromobactomycin can contribute, in an interconnected way, to the suppression of plant disease by Chromobacterium sp. strain C61. [ABSTRACT FROM AUTHOR]

Objective. To analyze the type 1 / type 2 cytokine balance in patients with systemic lupus erythematosus (SLE) according to the presence of renal disorder and activity status. Methods. We measured the serum levels of type 1 (IFN-γ, IL-12) and type 2 cytokines (IL-4, IL-10) as well as spontaneous and stimulated cytokine production from peripheral blood mononuclear cells (PBMC) in 40 patients with SLE. Results. Patients with lupus nephritis (LN) showed significantly lower levels of serum IL-12 and IFN-γ than those without LN. Production of IL-12 and IFN-γ by stimulated PBMC were also decreased in patients with LN. The circulating IL-12 correlated positively with IFN-γ, but inversely with IL-10. The SLEDAI scores correlated well with the ratio of IL-4/IFN-γ levels. Conclusion. The reduced production of IL-12 and IFN-γ and the resultant shift towards the type 2 cytokine phenotype may be associated with LN. [ABSTRACT FROM AUTHOR]