In order to clarify the usefulness of the S10-GERMS (S10-spc-alpha operon gene-encoded ribosomal protein mass spectrum) method for the discrimination of microbial isolates from the environment, the isolates with octylphenol polyethoxylate (OPEOn)-degrading capability from several soils in Japan were classified into 4 biodegradation patterns based on different final metabolic toxicants. Some isolates were identified as genera Chelatococcus and Mesorhizobium which have never been reported as OPEOn-degrading bacteria based on 16S rRNA gene sequences. The findings from this study demonstrate that the S10-GERMS method successfully discriminates the isolates at the strain level in the genus Pseudomonas. Moreover, this method is better than 16S rRNA gene sequence similarity because it precisely demonstrated that OPEOn-degrading bacteria in the genera Chelatococcus and Mesorhizobium might be new species. The S10-GERMS method is suggested as a useful tool for the discrimination and monitoring of man-made chemical-degrading bacteria isolated from the environment.
Uncertainty assessments of herbicide losses from rice paddies in Japan associated with local meteorological conditions and water management practices were performed using a pesticide fate and transport model, PCPF-1, under the Monte Carlo (MC) simulation scheme. First, MC simulations were conducted for five different cities with a prescribed water management scenario and a 10-year meteorological dataset of each city. The effectiveness of water management was observed regarding the reduction of pesticide runoff. However, a greater potential of pesticide runoff remained in Western Japan. Secondly, an extended analysis was attempted to evaluate the effects of local water management and meteorological conditions between the Chikugo River basin and the Sakura River basin using uncertainty inputs processed from observed water management data. The results showed that because of more severe rainfall events, significant pesticide runoff occurred in the Chikugo River basin even when appropriate irrigation practices were implemented.
This paper demonstrates the procedures for probabilistic assessment of a pesticide fate and transport model, PCPF-1, to elucidate the modeling uncertainty using the Monte Carlo technique. Sensitivity analyses are performed to investigate the influence of herbicide characteristics and related soil properties on model outputs using four popular rice herbicides: mefenacet, pretilachlor, bensulfuron-methyl and imazosulfuron. Uncertainty quantification showed that the simulated concentrations in paddy water varied more than those of paddy soil. This tendency decreased as the simulation proceeded to a later period but remained important for herbicides having either high solubility or a high 1st-order dissolution rate. The sensitivity analysis indicated that PCPF-1 parameters requiring careful determination are primarily those involve with herbicide adsorption (the organic carbon content, the bulk density and the volumetric saturated water content), secondary parameters related with herbicide mass distribution between paddy water and soil (1st-order desorption and dissolution rates) and lastly, those involving herbicide degradations.
The sensitivity of four isolates of Clonostachys rosea, potential biocontrol agents of Botrytis cinerea, to fungicides, insecticides, and herbicides used in the strawberry crop was evaluated in vitro. All fungicides inhibited mycelial growth and conidia germination of all isolates. The insecticides decreased both as well, although less intensely than the fungicides did. The herbicides were the least toxic. Suitable spraying intervals of fungicides and usage of compounds less toxic to C. rosea are crucial to successfully manage strawberry gray mold.
Eighteen novel compounds of 2,5-disubstituted-1,3,4-oxadiazoles containing benzimidazole moiety were synthesized from 1H-benzimidazole-2-carbohydrazide, carbon disulfide and alkyl halide or benzyl halide by multi-step reactions. The structures of the target compounds were confirmed by IR, 1H-NMR spectra and elemental analyses. Preliminary antifungal activities against Botrytis cinerea and Sclerotinia sclerotiorum were also evaluated by the mycelium growth rate method, and the results indicated that many target compounds possess excellent antifungal activity, even higher than the control fungicide (carbendazim).
The uptake of 14C labeled 3-phenoxybenzoic acid (I) was examined for Myriophyllum elatinoides. The uptake of 14C-I dissolved in water by the shoot/leaves amounted to 15.85% of the applied radioactivity (AR) after 0.5 days, and 14C translocation to the roots was minimal during 14 days. Slower uptake of the radioactivity from 14C-I treated sediment by the roots was observed (6.37%AR after 14 days) and 1.71%AR was translocated to the shoot/leaves. Oxidation, reduction and conjugation of I proceeded in the macrophyte.
Fipronil is a phenylpyrazole-class insecticide used for rice protection, and its pharmacological activity is an interruption of the GABA A receptor. Since fipronil suppresses GABAergic neurons, central nervous system (CNS) toxicity is well observed. However, fipronil has no influence on neurogenesis. Fipronil promoted hepatocyte vacuolization and thyroid oncogenesis only in rats. It had no genotoxic activity, and thyroid oncogenesis was promoted by accelerated thyroxin clearance under the genetic lack of thyroxine-binding globulin (TBG), suggesting an apparent rat-specific mechanism. Therefore, in relation to human health concerns, the most important toxicity of fipronil would be CNS toxicity, which was commonly observed in most of the toxicological studies with various species. Most of the NOAELs were established by CNS toxicity, and a minimum value was contributed for the ADI setting. Thus, the safety and human risk assessments are well ensured by the ADI.
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