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941.
Hua-Mao Jiang Zhong-Ze Fang Yun-Feng Cao Cui-Min Hu Xiao-Yu Sun Mo Hong Ling Yang Guang-Bo Ge Yong Liu Yan-Yan Zhang Qiang Dong Ren-Jie Liu 《Chemosphere》2013
Bisphenol A (BPA), the important endocrine-disrupting chemical (EDC), has been reported to be able to induce various toxicity. The present study aims to understand the toxicity behavior of bisphenol A through evaluating the inhibition profile of bisphenol A towards UDP-glucuronosyltransferase (UGT) isoforms. In vitro recombinant UGTs-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction was employed as probe reaction for all the tested UGT isoforms. The results showed that bisphenol A exerted stronger inhibition towards UGT2B isoforms than UGT1A isoforms. Furthermore, the inhibition kinetic type and parameters (Ki) were determined for the inhibition of bisphenol A towards UGT2B4, 2B7, 2B15, and 2B17. Bisphenol A exhibited the competitive inhibition towards UGT2B4, and noncompetitive inhibition towards UGT2B7, 2B15 and 2B17. The inhibition kinetic parameters (Ki) were calculated to be 1.1, 32.6, 5.6, and 19.9 μM for UGT2B4, 2B7, 2B15 and 2B17, respectively. In combination with the in vivo concentration of bisphenol A, the elevation of exposure dose was predicted to increase by 29.1%, 1%, 5.7%, and 1.6% for UGT2B4, 2B7, 2B15, and 2B17, indicating the high influence of bisphenol A towards the in vivo UGT2B isofroms-mediated metabolism of xenobiotics and endogenous substances. All these data provide the supporting information for deeper understanding of toxicology of bisphenol A. 相似文献
942.
MAREN BODE MATTHIAS HAAS TANYA FAYMONVILLE BRIGITTE THIEDE INGOLF SCHUPHAN BURKHARD SCHMIDT 《Journal of environmental science and health. Part. B》2013,48(3):201-222
In the present investigation, the oxidative metabolism of 14C-labeled metamitron was examined in plant cell cultures of tobacco overexpressing human P450 enzymes CYP1A1 or CYP1A2; special interest was in the aromatic hydroxylation of the herbicide. The oxidative metabolites deaminometamitron (DAM) and 4-hydroxydeaminometamitron (4-HDAM) were found in the untransformed control culture as well as in the transgenic culture. The transgenic cultures, however, exhibited higher turnover rates after 48 h of incubation with 20 μg 14C-metamitron per assay (untransformed: 40%, CYP1A1: 80%, CYP1A2: 100%). Primary metabolite 4-HDAM was partially found in glucosylated form in the transgenic cultures. As minor oxidative metabolites, 6-hydroxyphenyl-3-methoxymethyl-1,2,4-triazine-5(4H)-one and 3-hydroxymethyl-6-phenyl-1,2,4-triazine-5(4H)-one were identified in the transgenic cultures by GC-MS, LC-MS. Additionally, it could be demonstrated that both foreign enzymes (CYP1A1, CYP1A2) also catalyzed the deamination of metamitron. In a large-scale study (up to 400 μ g per assay) with the transgenic culture expressing CYP1A2, the high efficiency of this P450 system toward metamitron was demonstrated: turnover of the xenobiotic was almost complete with 400 μ g. Since large portions of unglucosylated 4-H-DAM were found, the activity of foreign CYP1A2 apparently exceeded that of endogenous O-glucosyltransferases of the tobacco cell culture. We concluded that in comparison to the nontransformed cell culture, the extent of metabolism was considerably higher in the transgenic cultures. The transgenic cell cultures expressing human CYP1A1 or CYP1A2 are thus suitable tools for the production of large quantities of primary oxidized metabolites of metamitron. 相似文献
943.
K.M.S. Sundaram 《Journal of environmental science and health. Part. B》2013,48(4):523-544
Abstract Foliar deposits, volatilization and persistence of azadirachtin‐A (AZ‐A) were investigated after application of four spray mixes prepared from a wettable powder (WP) and three emulsifiable concentrate (EC) formulations of neem. They were applied at the dosage rate of 50 g AI in 4 L/ha onto potted spruce seedlings in a laboratory spray chamber. Droplet‐size spectra and deposits were assessed using Kromekote® card/glass plate collection units. Foliar residues [dislodgeable residues (DR), penetrated residues (PR) and total residues (TR)] of AZ‐A and their volatilization were measured by HPLC at different intervals of time up to 60 h after treatment. Differences in the droplet‐size spectra and deposit levels were observed among the four spray mixes due to the influence of additives present in them. Dissipation half‐lives (DT50) of the DR, PR and TR in the foliage were low (range, 19.5 to 38.9 h) and varied according to the residue type and the spray mix used. The DT50 values of the DR were consistently lower (range, 19.5 to 31.9 h) than those of the PR (range, 30.5 to 38.9 h) due to preferential loss of the surface residues. The low DT50 values observed for the DR and TR in the foliage sprayed with the WP spray mix were attributed to the particulate nature of the deposit. AZ‐A volatilized appreciably from the DR rather than from the PR. The variations found in the amounts of AZ‐A volatilized (42 to 58%) and unaccountable (38 to 46%) from the initial TR values in spruce foliage, after 60 h, were attributed to the physical form of the deposits on the target surface and the influences of additives present in the different spray mixes. 相似文献
944.
The potential for negative effects caused by endocrine disrupting chemicals (EDCs) release into the environment is a prominent concern and numerous research projects have investigated possible environmental fate and toxicity. However, their sorption behavior by size fractions of soil and sediment has not been systematically represented. The sorption of bisphenol A (BPA), 17α-ethinyl estradiol (EE2) and phenanthrene (Phen) by different size fractions of soil and sediment were investigated. Sorption isotherms of EE2, BPA, and Phen by size fractions of soil (SL) and sediment (ST) were well fitted to the Freundlich model. The positive correlation between EE2, BPA and Phen sorption capacity (log Kd) of size fractions and their organic carbon (OC) content suggests that OC of size fractions in SL and ST should regulate sorption, while the surface area (SA) of size fractions may not account for sorption of EE2, BPA and Phen. Each size fraction of ST had higher sorption capacity (Kd or KOC) of EE2 and BPA than that of SL due to their difference in the polarity of organic matter (OM) between terrestrial and aquatic sources. Sorption capacity logKd for size fractions of SL and ST did not follow the order: clay > silt > sand due to the difference in OM abundance and composition between the size fractions. Large particle fractions of ST contributed about 80% to the overall sorption for any EE2, BPA, and Phen. This study was significant to evaluate size fractions of soil and sediment as well as their associated OM affecting EE2 and BPA sorption processes. 相似文献
945.
In this study, the presence of bisphenol A (BPA) in human placental and fetal liver samples collected from 1998 to 2008 was investigated to provide a more detailed analysis of the transfer of BPA across the placenta and fetal exposure to BPA. The average concentrations in placental samples were 12.6 ng g−1 for free BPA, 17.2 ng g−1 for BPA-glu, and 30.2 ng g−1 for total BPA. The highest concentrations in placental samples were 165 ng g−1 for free BPA, 178 ng g−1 for BPA-glu, and 280 ng g−1 for total BPA. Samples with higher levels of BPA-glu had higher levels of free BPA in general. Fetal age was observed to have a significant effect on BPA-glu levels in placental samples, but not on free or total BPA. The percentages of free BPA relative to total BPA for the placental samples varied considerably from 4.2% to 100%, suggesting that the ability of maternal liver and/or the placenta to conjugate BPA is highly variable during early to mid-gestation. The average concentrations in fetal liver samples were 9.02 ng g−1 for free BPA, 19.1 ng g−1 for BPA-glu, and 25.8 ng g−1 for total BPA. The highest concentrations in fetal liver samples were 37.7 ng g−1 for free BPA, 93.9 ng g−1 for BPA-glu, and 123 ng g−1 for total BPA. The percentages of free BPA level relative to total BPA for all fetal liver samples varied from 12.4% to 99.1%, indicating extensive variability in the ability of the human feto-placental unit to glucuronidate BPA. 相似文献
946.
小区生活污水的治理方案 总被引:2,自引:0,他引:2
对小区排污状况进行现场调查、分析和试验的基础上,综合对比目前处理小区生活污水的几种常用工艺,结合本小区的实际情况,提出用A/O法治理该小区的生活污水,治理后的废水出水水质达到国家废水综合排放标准(GB8978—96)二级标准,并且部分回收再利用。 相似文献
947.
948.
目的 评估长期贮存ZL205A铝合金的微观缺陷对性能的影响。方法 利用X射线无损检测研究平贮合金的缺陷等级分布,并进一步研究合金室温拉伸、高温拉伸、室温疲劳和室温冲击性能。结果 经过平贮12 a后的ZL205A铝合金,其微观缺陷即针孔等级位于1~6级,仅发现少量的伴生带状偏析。室温拉伸时,1~3级针孔样品的抗拉强度为380MPa,而5级针孔样品的抗拉强度大幅下降到340.5 MPa,表明室温下4级及以上针孔对于拉伸强度有着重要影响。高温拉伸时,仅在100℃表现为样品缺陷等级越高,抗拉强度越高的趋势。常温疲劳试验表明,在107周的寿命下,合金的疲劳极限为99.2 MPa。常温冲击试验发现,1级针孔样品的平均冲击吸收能量为3.19J,明显优于其他针孔等级样品。结论 室温拉伸和室温冲击时,材料的力学性能与缺陷等级密切相关。高温拉伸时,温度上升导致材料强度下降的作用超过了缺陷自身对性能的影响。 相似文献
949.
转基因棉花基因花粉散布频率及距离的研究 总被引:26,自引:0,他引:26
选用从国外引进的和我国自己培育的Bt基因抗虫棉和转tfd A基因抗除草剂棉花,研究了外源Bt基因和tfd A基因向周围环境遗传漂流的频率和距离。结果表明:无论是我国自行培育的转基因棉花,还是从国外引进的转基因棉花;无论是转Bt基因棉花,还是转tfd A基因棉花,导入到棉株体内的外源基因均可向周围环境漂流,其最高漂流频率为10.48%,最远漂流距离可达50m。防止外源基因向周围环境扩散的最有效方法是 相似文献
950.