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1.
Richard V. Burkhauser John Cawley Maximilian D. Schmeiser 《Economics & Human Biology》2009,7(3):307-318
There are several ways to measure fatness and obesity, each with its own strengths and weaknesses. The primary measure for tracking the prevalence of obesity has historically been body mass index (BMI). This paper compares long-run trends in the prevalence of obesity when obesity is defined using skinfold thickness instead of BMI, using data from the full series of U.S. National Health Examination Surveys. The results indicate that when one uses skinfold thickness rather than BMI to define obesity, the rise in the prevalence of obesity is detectable 10-20 years earlier. This underscores the importance of examining multiple measures of fatness when monitoring or otherwise studying obesity. 相似文献
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三氯乙烷(1,1,1-Trichloroethane,TCA)是一种易挥发的氯代烃,密度大于水,曾作为金属清洗剂和高效溶剂在工业上广泛应用.近年来三氯乙烷对环境及人类健康的危害引起人们的关注,其自然分解过程较为困难,在环境中的存在具有一定的持久性.由于不合理的排放和意外泄漏等原因,三氯乙烷已成为地下水中最普遍的污染物之一,严重威胁生态系统和人体健康,是美国环保署(EPA)所确定的优先污染物.研究表明,Peptococcaceae科的脱卤素杆菌属(Dehalobacter)细菌纯培养物或含有Dehalobacter的混合培养物可催化三氯乙烷及1,1,-二氯乙烷还原脱氯,在其降解过程中起关键作用[1 3],并可利用含有Dehalobacter的菌群对三氯乙烷污染场地进行生物治理[4],其中Dehalobacter 16SrRNA基因的特异性探针被用作生物标记物来评价三氯乙烷污染场地的生物降解潜能[4-5]. 相似文献
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A Majumdar S Reynolds N K Gupta 《Biochemical and biophysical research communications》1975,67(2):689-695
Met-tRNAfMet binding factor (EIF-1) has been purified more than 100 fold over crude high salt (0.5 M KCl) ribosomal wash. The purified factor binds 2 nmoles Met-tRNAfMet per mg protein and shows very little poly r(A) binding activity. Crude ribosomal high salt wash possesses significant amounts of poly r(A) binding activity and also binds to other RNAs. The bulk of this unspecific RNA binding protein is separated from EIF-1 by DEAE-cellulose chromatography. 相似文献
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Distribution of 1AL.1RS and 1BL.1RS wheat-rye translocations in Triticum aestivum using specific PCR
Chromosome arm 1RS of rye (Secale cereale) is a valuable resource for wheat (Triticum aestivum) improvement. 1AL.1RS and 1BL.1RS translocations play an important role in wheat breeding, since wheat carrying these chromosomal translocations has higher tolerance to biotic and abiotic stress. In this study, the presence of 1RS and the distribution of 1AL.1RS and 1BL.1RS wheat-rye translocations were examined in 66 Iranian cultivars and 70 regional foreign accessions of bread wheat, using three rye-specific primers (“RYER3/F3”, “O-SEC5′-A/O-SEC3′-R”, “PAWS5/S6”). Based on “RyeR3/F3”, the presence of 1RS was verified in 15 (23%) Iranian cultivars and in two (3%) foreign accessions. Further, “O-SEC5′-A/O-SEC3′-R” and “PAWS5/S6” were used to distinguish 1AL.1RS and 1BL.1RS translocations. According to results from these primers, 1BL.1RS was identified in 14 (21%) Iranian cultivars and two (3%) foreign accessions. The results confirm that “Sholeh” is the only cultivar (1.5%), among all cultivars and accessions, that carries 1AL.1RS. This study provides a useful tool in marker-assisted selection of materials containing 1RS, and in the creation of new Iranian common wheat cultivars with a larger genetic diversity in wheat breeding programs. 相似文献
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Fanny Schapira Claudine Gregori Josette Banroques 《Biochemical and biophysical research communications》1978,80(2):291-297
Using thin-layer acrylamide gel isoelectrofocusing, several bands of galactose-1-Phosphate uridylyl transferase were found in various human tissues. Liver transferase, as well as that of some other tissues, was resolved into several bands with pHi between 5.30 and 5.80; red cell enzyme was resolved into five bands with pHi between 5.0 and 5.45. The comparison of erythrocytes with their precursors, reticulocytes and erythroblasts, showed a striking difference: the pHi of the erythroblast enzyme was between 5.55 and 5.90 and that of reticulocytes between 5.30 and 5.50. It is possible that molecular aging is the cause of the anodisation of the erythrocyte transferase and the microheterogeneity of the enzyme observed in other tissues. 相似文献
7.
本文报道了竹节参中二种主要皂甙(R_(b1)和R_(g1)的HPLC定性和定量测定法。结果表明:人参皂甙R_(b1)和R_(g1)的含量较高。R_(b1)和R_(g1)的相对标准偏差分别为3.05%和3.18%,R_(b1)和R_(g1)的回收率分别为86.5~110.1%和94.7~102.7%。 相似文献
8.
M. Crisma G. M. Bonora C. Toniolo
V. Barone
E. Benedetti B. Di Blasio V. Pavone C. Pedone A. Santini F. FraternaliA. Bavoso
F. Lelj 《International journal of biological macromolecules》1989,11(6):345-352Conformational energy computations on the 1-aminocyclopropane-1-carboxylic acid mono-, di-, and tripeptide amides, (Ac-(Ac3c)n---NHMe (n=1−3), indicate that this C,-dialkylated, cyclic -amino acid residue is conformally restricted and that type-I(I′) β-bends and distorted 310-helices are particularly stable conformations for the di- and tripeptide amides, respectively. The results of the theoretical analysis are in agreement with those obtained in an i.r. absorption and 1H n.m.r. investigation in chloroform solution of A.c.3c-rich tri- and tetrapeptide esters. A comparisons is also made with the conclusions extracted from our previous work on peptides rich in Aib (-aminoisobutyric acid), Ac5c(1-aminocyclopentane-1-carboxylic acid), and Ac6c (1-aminocyclohexane-1-carboxylic acid). 相似文献
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Dennis J. Ashworth Tiee-Leou Shieh Ching-Jer Chang 《Chemico-biological interactions》1981,34(1):127-131
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Ethanol and acetaldehyde both prevent the formation of ethylene bysenescing cut carnation flowers. This is due to the almost complete inhibitionof the activity of 1-aminocyclopropane-carboxylic acid oxidase. Thesetreatmentsalso reduce the 1-aminocyclopropane-1-carboxylic acid content of the tissue andresult in a loss of protein. The protein content of treated flowers wassignificantly lower than that of control flowers, due to a general rather thanspecific loss of protein. This affects the metabolism of the flowers,preventingenzyme mediated reactions as well as cell growth and development. One enzymethat remained active was alcohol dehydrogenase, allowing for a constantshuttling between ethanol and acetaldehyde. 相似文献
12.
Polycystin-1 (Pc-1) is the 4303 amino acid multi-domain glycoprotein product of the polycystic kidney disease-1 (PKD1) gene.
Mutations in this gene are implicated in 85% of cases of human autosomal dominant polycystic disease. Although the biochemistry
of Pc-1 has been extensively studied its three dimensional structure has yet to be determined. We are combining bioinformatics,
computational and biochemical data to model the 3D structure and function of individual domains of Pc-1. A three dimensional
model of the C-type lectin domain (CLD) of Pc-1 (sequence region 405–534) complexed with galactose (Gal) and a calcium ion
(Ca+2) has been developed (the coordinates are available on request, e-mail: pletnev@hwi.buffalo.edu). The model has α/β structural
organization. It is composed of eight β strands and three α helices, and includes three disulfide bridges. It is consistent
with the observed Ca+2 dependence of sugar binding to CLD and identifies the amino acid side chains (E499, H501, E506, N518, T519 and D520) that
are likely to bind the ligand. The model provides a reliable basis upon which to map functionally important residues using
mutagenic experiments and to refine our knowledge about a preferred sugar ligand and the functional role of the CLD in polycystin-1.
Figure Carbohydrate binding site with bound galactose and calcium ion inC-lectin binding domain of polycystin-1 相似文献
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Prompt and delayed chlorophyll fluorescence have been studied in broken spinach chloroplasts at pH values down to 2.6. No direct effect of low pH on the primary charge separation in Photosystem II was observed. The irreversible inactivation of a secondary electron donor in a narrow pH range around pH 4.5 was demonstrated. At lower pH values the photooxidized form of a more primary electron donor, revealed by its efficient fluorescence quenching, was reduced with a half time of about 200 μs, 25% by another electron donor and 75% by back reaction with the reduced acceptor. The electron donation had a half time of 800 μs and was practically irreversible. The back reaction had a pH dependent half time: about 270 μs at pH 4 and increasing towards lower pH. The competition of both reactions resulted in a net efficiency of the charge separation at pH 4 of 25%, increasing towards lower pH. 相似文献
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The purified keratansulfate degrading enzyme from could hydrolyze desialyzed pig colonic mucin and milk oligosaccharides. Desialyzed pig colonic mucin was digested to produce GlcNAcβ(1→3)Gal, GlcNAc-6Sβ(1→3)Gal and resistant polymer. Lacto-N-tetraose and lacto-N-tetraitol were hydrolyzed endoglycosidically to release glucose and sorbitol, respectively. Therefore, this enzyme was found to be an endo-β-galactosidase of rather wide specificity. 相似文献
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威岭栽培黑麦抗白粉病特性导入小麦的研究 总被引:6,自引:0,他引:6
威岭黑麦(Weiling rye)是一个高抗白粉病(Erysiphe gramininis f.sp.tritici)的中国矮杆栽培黑麦。以Weiling rye作为白粉病抗源,高感白粉病小麦栽培品种My8443为母本,从Weiling rye与小麦My8443远缘杂交的BC_2F_6后代中鉴定出一个新的小麦-黑麦易位系No.147,以实现威岭黑麦白粉病抗性向普通栽培小麦的转移。No.147及其亲本的抗白粉病特性通过苗期和成株期优势生理小种混合接种和室内单生理小种接种鉴定,改良的染色体C-分带和基因组原位杂交技术(GISH。Ge- nomic in situ hybridization)被用于鉴定小麦和黑麦的染色质,酸性聚丙烯酰胺凝胶电泳(APAGE)被用于鉴定黑麦醇溶蛋白1RS特异条带,11个黑麦种属特异性标记SCM(Secale cereale marker)引物被用于扩增分析黑麦特异性简单重复序列(SSR)。研究结果证实No.147是一个新的高抗白粉病的1BL/1RS小麦-黑麦染色体易位系,并对其产生的细胞学机制进行了分析。论文对中国栽培黑麦抗性基因资源的利用和该易位系在小麦遗传育种改良中的利用价值进行了讨论。 相似文献
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利用PCR、DNA重组、原核与真核生物表达等技术从新疆短命植物东方旱麦草(Eremopyrum orientale)基因组中扩增出Rubisco大亚基基因rbcL(GenBank登录号为FJ346562),并构建了原核与真核表达载体pGEX4T-1-rbcL和pcDNA3-rbcL,随后分别在原核宿主BL21(DE3)和小鼠中进行了表达,并利用真核表达载体和纯化蛋白制备的抗体,对表达产物的特异性进行了Western印迹检测。结果表明:东方旱麦草的rbcL基因可读区包含1431 bp,与旱麦草rbcL基因的同源性达99.86%,推测编码476个氨基酸,分子量56 kD。该基因在BL21中以融合蛋白GST-RBCL形式表达并存在于包含体中,融合蛋白大小约为82 kD。RT-PCR检测到该基因在小鼠肝脏中的表达。利用真核表达载体与纯化融合蛋白进行联合免疫制备的RBCL抗体可与RBCL特异性地结合,这为短命植物东方旱麦草基因后续的免疫定位检测奠定了基础。 相似文献
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Leukocytes circulate freely in the bloodstream until receiving signals which activate adhesive mechanisms essential for immune responsiveness. Key mediators of these adhesion events are heterodimeric cell surface receptors called integrins. It is now apparent that several components may contribute to successful integrin-mediated adhesion: alterations in individual receptors lead to enhanced affinity for ligand; integrin clustering causes an increase in avidity; by spreading, the adhering cell is less susceptible to shear force. Model systems have allowed us to examine the contribution of each of these factors in generating adhesion. In more physiologically relevant situations, it can now be questioned whether integrin-mediated adhesion is regulated via alterations in receptor affinity or avidity, or whether both these mechanisms are involved. © 1996 Wiley-Liss, Inc. 相似文献
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