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991.
Quitain AT Sato N Daimon H Fujie K 《Journal of agricultural and food chemistry》2003,51(27):7926-7929
Hydrothermal treatment of an outer layer of a bark of Hinoki (Chamaecyparis obtusa) tree was investigated qualitatively for the possibility of utilizing residual forest biomass to produce valuable chemicals. Experiments were carried out in a semibatch reactor apparatus that allows the study of the effect of reaction temperatures in a single run. Gas chromatography-mass spectrometry analyses show the presence of useful chemicals such as furfural, aromatic compounds (1,3-di-tert-butyl benzene and 2,4-di-tert-butyl phenol), and fatty acids (myristic acid, palmitic acid, and stearic acid) in the products. 相似文献
992.
Eiki Watanabe Yukiko Kanzaki Hiroshi Tokumoto Ryoko Hoshino Hiroaki Kubo Hiroyuki Nakazawa 《Journal of agricultural and food chemistry》2002,50(1):53-58
For development of an indirect competitive enzyme-linked immunosorbent assay (ELISA) for the organophosphorus insecticide fenitrothion, the specificity of the antiserum R-3 generated with the bifunctional hapten, LysMNPA (2-[[[(3-methyl-4-nitrophenyl)oxy]methylcarbonyl]amino]-6-(2,4-dinitrophenyl)aminohexanoic acid) and the application to the residual analysis of some water samples were evaluated. At optimized ELISA conditions, the quantitative working range was from 1 to 39 ng/mL with a limit of detection of 0.3 ng/mL and an IC(50) value of 6 ng/mL. Cross-reactivity to structurally similar organophosphorus compounds and related chemicals was determined. The antiserum R-3 showed significant cross-reactivity with fenitrooxon and 3-methyl-4-nitrophenol, which have a 3-methyl-4-nitrophenoxy group as common structures, but showed relatively low cross-reactivity with other compounds. Each water sample (river water, tap water, purified water, and bottled water) had a matrix effect and was investigated by adding Tween 20 in the assay buffer. These four kinds of water samples were fortified with fenitrothion at several concentration levels and were directly analyzed with only dilution with an equal volume of antiserum solution. The mean recovery was 105.9%, and the mean coefficient of variation was 10.9%. The results suggested that the developed ELISA would be very suitable for a preliminary screening for fenitrothion in water samples at such low levels. 相似文献
993.
994.
Thaumatin, a sweet protein that contains no cysteine residues and eight intramolecular disulfide bonds, aggregates upon heating at pH 7.0 above 70 degrees C, and its sweetness thereby disappears. The aggregate can be solubilized by heating in the presence of both thiol reducing reagent and SDS. This molecular aggregation depended on the protein concentration during heating and was suppressed by the addition of N-ethylmaleimide or iodoacetamide, indicating a thiol-catalyzed disulfide interchange reaction between heat-denatured molecules. An amino acid analysis of the aggregates suggested that the cysteine and lysine residues were reduced, and the formation of a cysteine residue and a lysinoalanine residue was confirmed. The reduction and formation of these residues stoichiometrically satisfied the beta-elimination of a cystine residue. The disulfide interchange reaction was catalyzed by cysteine; that is, a free sulfhydryl residue was formed via beta-elimination of a disulfide bond. Intermolecular disulfide bonds were probably formed between thaumatin molecules upon heating at pH 7.0, which led to the aggregation of thaumatin molecules. 相似文献
995.
Nagahori H Yoshino H Tomigahara Y Isobe N Kaneko H Nakatsuka I 《Journal of agricultural and food chemistry》2000,48(11):5760-5767
14C-Labeled furametpyr [N-(1,3-dihydro-1,1, 3-trimethylisobenzofuran-4-yl)-5-chloro-1, 3-dimethylpyrazole-4-carboxamide, Limber] was dosed to male and female rats at 1 (low dose) and 200 or 300 mg/kg (high dose). Elimination of furametpyr was rapid, and the dosed (14)C was substantially excreted within 7 days (45.5-53.3% in feces, 44.1-53. 8% in urine, and 0.01% in expired air). However, (14)C excretion rate showed sex- and dose-related differences, more rapid in males at low dose. (14)C concentrations in tissues decreased rapidly to generally low levels at 7 days (<0.004 ppm with the low dose and <1. 1 ppm with the high dose). Forty metabolites were detected, and 13 metabolites and 4 glucuronides were identified. A small amount of unchanged furametpyr was detected in feces (0.1-0.5% of the dose). The major metabolites in tissues were N-demethylated metabolites. In a bile study, 52.5-54.2% of the dosed (14)C was rapidly excreted into bile within 2 days. The absorption ratio was estimated to be >93.7% for the low dose (1 mg/kg). Major metabolites in bile were glucuronic acid conjugates of furametpyr hydroxides. On the basis of the results, furametpyr is substantially absorbed from the gastrointestinal tract after oral administration, rapidly distributed to tissues, extensively metabolized, and excreted into urine and bile or feces. 相似文献
996.
997.
Takaku T Mikata K Matsui M Nishioka K Isobe N Kaneko H 《Journal of agricultural and food chemistry》2011,59(9):5001-5005
To estimate the metabolic profile of trans-permethrin in humans, a comparison of the in vitro metabolism of trans-permethrin in humans and rats was conducted using hepatic microsomes, and cytochrome P450 and UDP-glucuronyltransferase isoforms, which catalyze the metabolism of 3-phenoxybenzyl alcohol (PBalc) and 3-phenoxybenzoic acid (PBacid), respectively. In humans and rats, the major metabolic reaction of trans-permethrin in microsomal incubations was the cleavage of ester linkage to give PBalc, followed by oxidation to 4'-OH-PBalc, 4'-OH-PBacid, and PBacid. As to 4'-hydroxylation of PBalc, several CYPs were able to catalyze the reaction, and CYP2E1 was identified as a predominant isoform. PBacid and its conjugates (glucuronide and glycine) are major urinary metabolites of trans-permethrin in mammals. PBacid is also a metabolite of several pyrethroids, and has been used as a biomarker of human exposure to pyrethroids. Our study indicated that there was no difference in glucuronyltransferase activity of PBacid between humans and rats, and that only UGT1A9 can catalyze the glucuronidation of PBacid among human UGTs. Some UGT1A9 variants are known to have poor glucuronidation activity. From these results, it was assumed that deficiency or polymorphism of UGT1A9 might affect the profile of PBacid and its conjugates in urine collected from persons exposed to trans-permethrin or other pyrethroids. These results are helpful for understanding the metabolism of trans-permethrin in humans and determining methods for quantification of target analytes for assessment of human exposure to trans-permethrin and other pyrethroids that give PBacid and its conjugates as urinary metabolites. 相似文献
998.
Kaneko H 《Journal of agricultural and food chemistry》2011,59(7):2786-2791
Synthetic pyrethroids, a major insecticide group, are used worldwide to control agricultural and household pests. Mammalian metabolism of pyrethroids was substantially launched in the 1960s and 1970s by the research groups of Professor Casida and Sumitomo Chemical Co., which made great contributions to the elucidation of their metabolic fates. They showed that ester hydrolysis and oxidation play predominant roles in mammalian metabolism of pyrethroids and that rapid metabolism leads to low mammalian toxicity. These metabolic reactions are mediated by carboxylesterases and CYP isoforms, the resultant metabolites then undergoing various conjugation reactions. In general, there are substantially neither significant species differences in metabolic reactions of pyrethoids nor metabolic differences among their chiral isomers except with fenvalerate, one isomer of which yields a lipophilic conjugate causing toxicity. 相似文献
999.
Kyotaro Noguchi Qingmin Han Masatake G. Araki Tatsuro Kawasaki Shinji Kaneko Masamichi Takahashi Yukihiro Chiba 《Journal of Forest Research》2011,16(4):284-291
Fine roots play a key role in carbon and nutrient dynamics in forested ecosystems. Fine-root dynamics can be significantly
affected by forest management practices such as thinning, but research on this topic is limited. This study examined dynamics
of fine roots <1 mm in diameter in a 10-year-old stand of hinoki cypress (Chamaecyparis obtusa) for 3 years following thinning (65% in basal area). Fine-root production and mortality rates were estimated using a minirhizotron
technique in combination with soil coring. In both thinned and un-thinned control plots, fine-root elongation occurred from
early spring to winter (March to December) and fluctuated seasonally. In the thinned and the control plots, the annual fine-root
production rates were estimated to be 101 and 120 g m−2 year−1, respectively, whereas the estimated annual fine-root mortality rates were 77 and 69 g m−2 year−1, respectively. At 3 years after thinning, live fine-root biomass was significantly smaller in the thinned plot (143 g m−2) than in the control plot (218 g m−2), whereas dead fine-root biomass was not (147 and 103 g m−2, respectively). Morphological and physiological indices of fine roots such as diameter, specific root length, and root tissue
density of the live fine roots was similar in both plots. These results suggested that thinning tended to decrease biomass
and production of fine roots, but the effects on characteristics of fine roots would be less evident. 相似文献
1000.
We investigated the effect of light intensity on diurnal differences in secondary wall formation of tracheids. Saplings of
Cryptomeria japonica were grown in growth chambers with light intensity cycles set for 12-h high light: 12-h low light by combining two of four
light intensity levels: 1.5, 2.8, 4.3, and 10.0 klx. Volumetric changes of differentiating cells were monitored by measuring
the tangential strain on the inner bark surface, and the innermost surface of developing secondary walls of differentiating
tracheids during the high-light and low-light periods was observed by field-emission scanning electron microscopy. Changes
in the aspects of the innermost surface of developing secondary walls and the tangential strain corresponded to changes in
the light intensity level. Cellulose microfibrils were clearly observed when the light intensity was high (10.0 or 4.3 klx)
and the volume of differentiating cells was low, while abundant amorphous material was observed when the light intensity was
lowest (1.5 klx) and the cells were turgid, regardless of the light intensity cycle. These results suggest that the diurnal
periodicity in the supply of cell wall components to developing secondary walls is associated with changes in light intensity
during the photoperiodic cycle. 相似文献