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21.
花生种子吸胀2d后,子叶中肽链内切酶活性上升,贮藏蛋白质开始降解。高活力种子肽链内切酶活性在吸胀2d后迅速上升,至4d时达到高峰,而中等活力种子的肽链内切酶活性上升速度绶慢。高活力种子萌发时贮藏蛋白质降解速度高于中等活力种子。中等活力种子经PEG和PUT处理可提高种子活力,也促进了种子贮藏蛋白质降解能力的提高。 相似文献
22.
Summary Predictive microbiology can be used to determine and predict the shelf-life of perishable foods under commercial distribution conditions based on microbial growth kinetics. This paper presents general microbial growth kinetics with the Monod model and the Gompertz function. Additional models are given to describe effects of food composition (e. g.a
w) and environmental conditions (e.g. temperature, gas atmosphere) as well as their interaction on the growth kinetic parameters (lag time and specific growth rate). These models can be used to predict the time to reach a critical level under any constant conditions within the range tested. A combination of microbial kinetics with an engineering accumulation approach can be used to predict the final microbial level in a food, or the loss of shelf-life, for any known time-temperature sequence, if there is no history effect or the history effect is negligible. A time-temperature indicator, could be used for predicting the remaining shelf-life of perishable foods under any distribution condition based on microbial growth kinetics.Mention of brand or firm names does not constitute an endorsement by the US Department of Agriculture over others of a similar nature not mentioned. 相似文献
23.
盐或低温胁迫对花生幼苗下胚轴ATP酶和质膜中PIP2含量的影响 总被引:2,自引:0,他引:2
经6%-12%Dextran T70密度梯度离心,获得了纯度较高的7d龄花生幼苗下胚轴质膜和液泡膜制剂。150mmol/L NaCl或10℃低温处理花生幼苗24h,其下胚轴质膜上的Mg^2+激活的ATPase活性分别提高了37.6%和17.2%;Ca^2+-ATPase活性分别提高45.8%和33.6%。上述盐或低温处理也提高了液泡膜上Mg^2+激活的ATPase活性,分别为对照的141.2%和1 相似文献
24.
H.C. Chan S.H. Law P.S. Leung L.X.M. Fu P.Y.D. Wong 《The Journal of membrane biology》1997,156(3):241-249
The β-adrenergic (cAMP-dependent) regulation of Cl− conductance is defective in cystic fibrosis (CF). The present study explored alternative regulation of anion secretion in
CF pancreatic ductal cells (CFPAC-1) by angiotensin II (AII) using the short-circuit current (I
SC
) technique. An increase in I
SC
could be induced in CFPAC-1 cells by basolateral or apical application of AII in a concentration-dependent manner (EC50 at 3 μm and 100 nm, respectively). Angiotensin receptor subtypes were identified using specific antagonists, losartan and PD123177, for AT1 and AT2 receptors, respectively. It was found that losartan (1 μm) could completely inhibit the AII-induced I
SC
, whereas, PD123177 exerted insignificant effect on the I
SC
, indicating predominant involvement of AT1 receptors. The presence of AT1 receptors in CFPAC-1 cells was also demonstrated by immunohistochemical studies using specific antibodies against AT1 receptors. Confocal microscopic study demonstrated a rise in intracellular Ca2+ upon stimulation by AII indicating a role of intracellular Ca2+ in mediating the AII response. Depletion of intracellular but not extracellular pool of Ca2+ diminished the AII-induced I
SC
. Treatment of the monolayers with a Cl− channel blocker, DIDS, markedly reduced the I
SC
, indicating that a large portion of the AII-activated I
SC
was Cl−-dependent. AII-induced I
SC
was also observed in monolayers whose basolateral membranes had been permeabilized by nystatin, suggesting that the I
SC
was mediated by apical Cl− channels. Our study indicates an AT1-mediated Ca2+-dependent regulatory mechanism for anion secretion in CF pancreatic duct cells which may be important for the physiology
and pathophysiology of the pancreas.
Received: 17 June 1996/Revised: 14 November 1996 相似文献
25.
本文根据吴征镒教授对中国种子植物属分市区类型研究结果,研制出定量化研究区域性种子植物区系的电子计算机程序,应用本程序可完成某区系的分布区类型统计分析,科属组成分析和与其它地区以共有属关系构建的相似性系数的谁知盘中计算,同时可大量节省研究人员的劳动强度和时间,对提高研究水平有一定的效果。 相似文献
26.
足月分娩的新鲜胎盘组织制成匀浆后,经高速离心、超速离心,谷胱甘肽(GSH)Sepharose 6B亲合层析,Amicon pM-10膜超过滤及高效液相层析,最终经SDS-PAGE鉴定,结果呈现单一亚基区带,其亚基分子量为25000。 根据我们现有高效液相设备条件,用ODS柱代替RadulovicL等报道的特异阴离子柱,用磷酸盐洗脱液代替含谷胱甘肽、二硫苏糖醇及氯化钾的梯度洗脱液,从人胎盘组织成功地制备了谷胱甘肽硫转移酶(GST)纯酶,全过程在15min内完成,保留时间及主峰面积的重复性均较理想,7次实验结果的变异系数为0.2%,最终纯化578.9倍。本研究为各种形式GST的纯化制备提供了一个新的、重复性好、分辨率高及回收理想的简易方法。 相似文献
27.
本文首次报道了五步蛇身体主要部位的数量性状与其排毒量的关系。其中我们发现与排毒量有关的部位是头积、体粗、体重、佛指长。 相似文献
28.
Fungal metabolism and detoxification of fluoranthene. 总被引:1,自引:0,他引:1
J V Pothuluri R H Heflich P P Fu C E Cerniglia 《Applied and environmental microbiology》1992,58(3):937-941
Five metabolites produced by Cunninghamella elegans from fluoranthene (FA) in biotransformation studies were investigated for mutagenic activity towards Salmonella typhimurium TA100 and TA104. Whereas FA displayed positive, dose-related mutagenic responses in both tester strains in the presence of a rat liver homogenate fraction, 3-FA-beta-glucopyranoside, 3-(8-hydroxy-FA)-beta-glucopyranoside, FA trans-2,3-dihydrodiol, and 8-hydroxy-FA trans-2,3-dihydrodiol were negative. 9-Hydroxy-FA trans-2,3-dihydrodiol showed a weak positive response in S. typhimurium TA100. Mutagenicity assays performed with samples extracted at 24-h intervals during incubation of C. elegans with FA for 120 h showed that mutagenic activity decreased with time. Comparative studies with rat liver microsomes indicated that FA trans-2,3-dihydrodiol, the previously identified proximal mutagenic metabolite of FA, was the major metabolite. The circular dichroism spectrum of the rat liver microsomal FA trans-2,3-dihydrodiol indicated that it was optically active. In contrast, the circular dichroism spectrum of the fungal FA trans-2,3-dihydrodiol showed no optical activity. These results indicate that C. elegans has the potential to detoxify FA and that the stereochemistry of its trans-2,3-dihydrodiol metabolite reduces its mutagenic potential. 相似文献
29.
G B Quistad S Suwanrumpha M A Jarema M J Shapiro W S Skinner G C Jamieson A Lui E W Fu 《Biochemical and biophysical research communications》1990,169(1):51-56
The structures are given for five paralytic acylpolyamines from the venom of the funnel web spider, Agelenopsis aperta. The acyl moieties are derived from (3-indolyl)acetic acid, (4-hydroxy-3-indolyl)acetic acid, and 4-hydroxybenzoic acid. The polyamine portions of the toxins are novel. Three toxins (AG489, AG505, and AG452) contain 1, 5, 9, 13, 18, 22-hexaazadocosane which is unique as a natural polyamine because of its length and hydroxylation at the 5-aza position. The polyamine portions of two other alpha-agatoxins (AG488 and AG504) are unusual also, containing guanidinooxy moieties. 相似文献
30.
From ten genera and 146 bacterial strains, 22 strains producing alpha-amino acid ester hydrolase were selected. Among them, AS 1.586 and 41-2 were the best. The optimal conditions for synthesis of cephalexin by pseudomonas aeruginosa 1.204 were investigated. The optimal pH and temperature for enzymatic synthesis reaction was pH 6.8 and 25 degrees C, respectively. By using 1% 7-ADCA, 3% PGME and 4% biomass, about 70% of 7-ADCA was converted to cephalexin under the mentioned conditions. 相似文献