Sugitate K.,Agilent Technologies |
Saka M.,The Institute of Environmental Toxicology
Journal of Pesticide Science | Year: 2015
Matrix removal ability of several new types of Solid Phase Extraction (SPEs) column was tested. E-HyCu is made of new type of material, chemically-modified carbon fibers, and can remove food components, monoacylglycerols, tocopherols, and sterols, etc. Z-Sep+ and Z-Sep/C18 are also new types of materials that contain zirconium dioxide. Z-Sep+ and Z-Sep/C18 are used for high lipid samples as the dispersive SPE in the QuEChERS method. We evaluated these sorbents as filled up columns. In our previous study, we reported that when the analytical method based on the multiresidue method is applied, monoacylglycerols are the most significant components that cause a matrix enhancement effect on pesticides in food using GC-MS. These new types of SPEs could remove not only monoacylglycerols, but also fatty acids, tocopherols, flavonoids, and sterols. The matrix enhancement effects of approximately 260 pesticides spiked in brown rice extracts pretreated with these SPEs were dramatically reduced. © Pesticide Science Society of Japan.
Boulange J.,Tokyo University of Agriculture and Technology |
Kondo K.,The Institute of Environmental Toxicology |
Phong T.K.,University of Queensland |
Watanabe H.,Tokyo University of Agriculture and Technology
Journal of Pesticide Science | Year: 2012
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. © Pesticide Science Society of Japan.
Ohnuma A.,Toho University |
Ohnuma A.,The Institute of Environmental Toxicology |
Conlon J.M.,United Arab Emirates University |
Iwamuro S.,Toho University
Comparative Biochemistry and Physiology - C Toxicology and Pharmacology | Year: 2010
Previous studies led to the isolation of antimicrobial peptides (AMPs) of the brevinin-2, palustrin-2, and ranatuerin-2 families from skin extracts and/or skin secretions of the Japanese mountain brown frog, Rana ornativentris. In the present study, we cloned cDNAs encoding the precursors of brevinin-2Oc, palustrin-2Oa, and ranatuerin-2Ob and -2Oe from skin total RNA preparations from adult R. ornativentris and established a semi-quantitative RT-PCR system to measure the concentrations of these mRNAs. The levels of preprobrevinin-2 and preproranatuerin-2 mRNAs in the skin specimens of developing R. ornativentris larva were detectable only at stages later than the onset of metamorphosis and reached peaks at the stage of metamorphic climax. In contrast, prepropalustrin-2 mRNA was detected prior to the onset of metamorphosis and levels peaked at stages earlier than those of the other two mRNAs. In adult animals, preprobrevinin-2 and preproranatuerin-2 gene transcripts were detected at low levels in the small intestine and skeletal muscle but not in the stomach, liver, or kidney, whereas prepropalustrin-2 gene transcripts were detected at relatively high concentrations in all tissues examined. These results indicate that the expression of amphibian AMP genes is correlated with metamorphosis but is subjected to differential regulation. © 2009 Elsevier Inc. All rights reserved.
Satsuma K.,The Institute of Environmental Toxicology
Pest Management Science | Year: 2010
BACKGROUND: Linuron is a globally used phenylurea herbicide, and a large number of studies have been made on themicrobial degradation of the herbicide. However, to date, the few bacteria able individually to mineralise linuron have been isolated only from European agricultural soils. An attempt was made to isolate linuron-mineralising bacteria from Japanese river sediment using a uniquely designed river ecosystem model (microcosm) treated with 14C-ring-labelled linuron (approximately 1 mgL-1). RESULTS: A linuron-mineralising bacterium that inhabits river sediment was successfully isolated. The isolate belongs to the genera Variovorax and was designated as strain RA8. Strain RA8 gradually used linuron in basal salt medium (5.2mg L-1) with slight growth. In 15 days, approximately 25% of 14C-linuron was mineralised to 14CO2, with 3,4-dichloroaniline as an intermediate. Conversely, in 100-fold diluted R2A broth, strain RA8 rapidly mineralised 14C-linuron (5.5 mg L-1) and more than 70% of the applied radioactivity was released as 14CO2 within 3 days, and a trace amount of 3,4-dichloroaniline was detected. Additionally, the isolate also degradedmonolinuron,metobromuron and chlorobromuron, but not diuron, monuron or isoproturon. CONCLUSION: Although strain RA8 can grow on linuron, some elements in the R2A broth seemed significantly to stimulate its growth and ability to degrade. The isolate strictly recognised the structural difference between N-methoxy-N-methyl and N,N-dimethyl substitution of various phenylurea herbicides. © 2010 Society of Chemical Industry.
Satsuma K.,The Institute of Environmental Toxicology |
Masuda M.,The Institute of Environmental Toxicology |
Sato K.,The Institute of Environmental Toxicology
Applied and Environmental Microbiology | Year: 2012
O-Demethylation of insecticide methoxychlor is well known as a phase I metabolic reaction in various eukaryotic organisms.Regarding prokaryotic organisms, however, no individual species involved in such reaction have been specified and characterized so far. Here we successfully isolated abacterium that mediates oxidative transformation of methoxychlor, including O-demethylation and dechlorination, from river sediment. The isolate was found to be closely related to Bradyrhizobium elkanii at the 16S rRNA gene sequence level (100% identical). However, based on some differences in the physiological properties of this bacterium, we determined that it was actually a different species, Bradyrhizobium sp. strain 17-4. The isolate mediated O-demethylation of methoxychlor to yield a monophenolic derivative [Mono-OH; 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl) ethane] as the primary degradation product. The chiral high-performance liquid chromatography (HPLC)analysis revealed that the isolate possesses high enantioselectivity favoring the formation of (S)-Mono-OH (nearly 100%). Accompanied by the sequential O-demethylation to form the bis-phenolic derivative Bis-OH [1,1,1-trichloro-2,2-bis(4-hydroxyphenyl)ethane],oxidative dechlorination of the side chain proceeded, and monophenolic carboxylic acid accumulated, followed by the formation of multiple unidentified polar degradation products. The breakdown proceeded more rapidly when reductively dechlorinated (dichloro-form) methoxychlor was applied as the initial substrate. The resultant carboxylic acids and polar degradation products are likely further biodegraded by ubiquitous bacteria. The isolate possibly plays an important role for complete degradation (mineralization) of methoxychlor by providing the readily biodegradable substrates. © 2012, American Society for Microbiology.