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1.
2.
The Social Construction of Virtue: The Moral Life of Schools. George W. Noblit and Van O. Dempsey. Albany: State University of New York Press, 1996. 225 pp.  相似文献   

3.
AIMS: To profile the fractions of bacteria in heat-treated activated sludge capable of producing hydrogen and subsequently to isolate those organisms and confirm their ability to produce hydrogen. METHODS AND RESULTS: Profiling the community composition of the microflora in activated sludge using 16S rRNA gene-directed polymerase chain reaction-denaturing gradient gel electrophoresis suggested that a majority of bacteria were various Clostridium species. This was confirmed by clone library analysis, where 80% of the cloned inserts were Clostridium sp. A total of five isolates were established on solid media. Three of them, designated as W1, W4 and W5, harboured the hydrogenase gene as determined by PCR and DNA sequence analysis (99% similarity). These isolates were similar to Clostridium butyricum and Clostridium diolis as determined by 16S rRNA gene sequence. A maximum hydrogen production yield of 220 ml H(2) g(-1) glucose was achieved by W5, which was grown on improved mineral medium by batch fermentation without pH adjustment and nitrogen sparging during fermentation. Accumulation of malic acid and fumaric acid during hydrogen fermentation might lead to higher hydrogen yields for W4 and W5. W1 is the first reported Clostridium species that can tolerate microaerobic conditions for producing hydrogen. CONCLUSION: Clostridium species in heat-treated activated sludge were the most commonly identified bacteria responsible for hydrogen production. Specific genetic markers for strains W1, W4 and W5 would be of great utility in investigating hydrogen production at the molecular level. Two previously described primer sets targeting hydrogenase genes were shown not to be specific, amplifying other genes from nonhydrogen producers. SIGNIFICANCE AND IMPACT OF THE STUDY: Clostridium species isolated from heat-treated activated sludge were confirmed as hydrogen producers during dark hydrogen fermentation. The isolates will be useful for studying hydrogen production from wastewater, including the process of gene regulation and hydrogenase activity.  相似文献   

4.
We hypothesize that aggregation of thermoalkalophilic lipases could be a thermostability mechanism. The conserved tryptophans (W211, W234) in the lid are of particular interest owing to their previous involvements in aggregation and thermostability mechanisms in many other proteins. The thermoalkalophilic lipase from Bacillus thermocatenulatus (BTL2) and its mutants (W211A, W234A) were expressed and purified to homogeneity. We found that, when aggregated, BTL2 is more thermostable than its non-aggregating form, showing that aggregation potentiates thermostability in the thermoalkalophilic lipase. Among the two lid mutants, the W211A lowered aggregation tendency drastically and resulted in a much less thermostable variant of BTL2, which indicated that W211 stabilizes the intermolecular interactions in BTL2 aggregates. Further thermoactivity and CD spectroscopy analyses showed that W211A also led to a strong decrease in the optimal and the melting temperature of BTL2, implying stabilization by W211 also to the intramolecular interactions. The other lid mutant W234A had no effects on these properties. Finally, we analyzed the molecular basis of these experimental findings in-silico using the dimer (PDB ID: 1KU0) and the monomer (PDB ID: 2W22) lipase structures. The computational analyses confirmed that W211 stabilized the intermolecular interactions in the dimer lipase and it is critical to the stability of the monomer lipase. Explicitly W211 confers stability to the dimer and the monomer lipase through distinct aromatic interactions with Y273-Y282 and H87-P232 respectively. The insights revealed by this work shed light not only on the mechanism of thermostability and its relation to aggregation but also on the particular role of the conserved lid tryptophan in the thermoalkalophilic lipases.  相似文献   

5.
The Evolution of Mind . Steven W. Gangestad and Jeffry A. Simpson, eds. New York: Guilford Press 2007; 448 pp.  相似文献   

6.
AIMS: To isolate and characterize oil-degrading microorganisms from contaminated (scale) soil. METHODS AND RESULTS: Oil-degrading microorganisms were isolated from enrichment cultures of scale soil. Each isolate was identified using 16S rDNA gene and oil degradability was determined on both unused and used lubricating oil. The weight of the extracted remaining oil revealed that most isolates degraded unused lubricating oil more than used lubricating oil. Chemical composition of oil analysed by TLC-FID and GC-MS demonstrated that Nocardia simplex W9 degraded used oil the best, and resulted in a decrease in saturates, aromatics and resins to 52.46, 38.13 and 18.81%, respectively. CONCLUSIONS:Nocardia simplex W9 is the best degrader, among all the isolates, on both used and unused lubricating oil. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of Nocardia simplex W9 in scale soil enables iron to be recycled by biodegradation.  相似文献   

7.
The Prehistory of Missouri. Michael J. O'Brien and W. Raymond Wood. Columbia: University of Missouri Press, 1998. 418 pp.  相似文献   

8.
The Cultural Study of Law: Reconstructing Legal Scholarship. Paul W. Kahn. Chicago: University of Chicago Press, 1999. 169 pp.  相似文献   

9.
The Cambridge History of the Native Peoples of the Americas: Vol. 2: Mesoamerica, Part 1. Richard E. W. Adams and Murdo J. MacLeod. eds. Cambridge: Cambridge University Press, 2000. 571 pp.
The Cambridge History of the Native Peoples of the Americas: Vol. 2: Mesoamerica, Part 2. Richard E. W. Adams and Murdo J. MacLeod. eds. Cambridge: Cambridge University Press, 2000. 455 pp.  相似文献   

10.
We analyzed 48 invasive isolates of Neisseria meningitidis that were isolated from meningitis cases in Burkina Faso (April 2002 to April 2003). Thirty-nine of these isolates had the phenotype (serogroup:serotype:serosubtype) W135:2a:P1.5,2, eight isolates were A:4:P1.9 and one isolate was nongroupable:nonserotypable:nonserosubtypable. Genotyping of meningococcal isolates showed that W135 isolates belonged to the sequence type (ST)-11. The nongroupable isolate was of genogroup W135 and belonged to ST-192. Isolates of serogroup A belonged to ST-2859 (a member of the subgroup III/ST-5 clonal complex). W135 (ST-11) isolates involved in meningitis outbreaks in Burkina Faso differed from those involved in the Hajj-2000 associated outbreak by their pulsed-field gel electrophoresis profile. These data confirm the changing epidemiology of meningococcal infection in Burkina Faso with the establishment and expansion of serogroup W135 N. meningitidis strains of the ET-37/ST-11 clonal complex, as well as the emergence of a new clone within the subgroup III/ST-5 clonal complex.  相似文献   

11.
The Cultural Analysis of Kinship: The Legacy of David M. Schneider. Richard Feinberg and Martin Ottenheimer. eds. Champaign: University of Illinois Press, 2001. 235 pp.
Filiation and Affiliation. Harold W. Scheffler. Cambridge: Westview Press, 2001. 202 pp.  相似文献   

12.
The Continuing Demographic Transition. Gavin W. Jones. Robert M. Douglas. John C. Caldwell. and Rennie D'Souza. eds. New York: Oxford University Press, 1998. 454 pp.  相似文献   

13.
Nieslanik BS  Ibarra C  Atkins WM 《Biochemistry》2001,40(12):3536-3543
Binding of a hydrophobic glutathione product conjugate to rGST A1-1 proceeds via a two-step mechanism, including rapid ligand docking, followed by a slow isomerization to the final [GST.ligand] complex, which involves the localization of the flexible C-terminal helix. These kinetically resolved steps have been observed previously by stopped-flow fluorescence with the wild-type rGST A1-1, which contains a native Trp-21 approximately 20 A from the ligand binding site at the intrasubunit domain-domain interface. To confirm this binding mechanism, as well as elucidate the effects of truncation of the C-terminus, we have further characterized the binding and dissociation of the glutathione-ethacrynic acid product conjugate (GS-EA) to wild-type, F222W:W21F, and Delta209-222 rGST A1-1 and wild-type hGST A1-1. Although modest kinetic differences were observed between the hGST A1-1 and rGST A1-1, stopped-flow binding studies with GS-EA verified that the two-step mechanism of ligand binding is not unique to the GST A1-1 isoform from rat. An F222W:W21F rGST A1-1 double mutant provides a direct fluorescence probe of changes in the environment of the C-terminal residue. The observation of two relaxation times during ligand binding and dissociation to F222W:W21F suggests that the C-terminus has an intermediate conformation following ligand docking, which is distinct from its conformation in the apoenzyme or localized helical state. For the wild-type, Delta209-222, and F222W:W21F proteins, variable-temperature stopped-flow experiments were performed and activation parameters calculated for the individual steps of the binding reaction. Activation parameters for the binding reaction coordinate illustrate that the C-terminus provides a significant entropic contribution to ligand binding, which is completely realized within the initial docking step of the binding mechanism. In contrast, the slow isomerization step is enthalpically driven. The partitioning of entropic and enthalpic components of binding energy was confirmed by isothermal titration calorimetry with wild-type and Delta209-222 rGST A1-1.  相似文献   

14.
Synthetic peptides corresponding to the calmodulin-binding domain of the human erythrocyte Ca2+ pump were prepared representing residues 2-29 (C28W), 2-21 (C20W), 2-16 (C15W), and 16-29 (C14) of the sequence (James, P., Maeda, M., Fisher, R., Verma, A. K., Krebs, J., Penniston, J. T., and Carafoli, E. (1988) J. Biol. Chem. 263, 2905-2910). Peptides C28W, C20W, and C15W bound to calmodulin with an apparent 1:1 stoichiometry in the presence of Ca2+ and inhibited the activation of the Ca2+ pump by calmodulin, while C14 was ineffective. Substituting tyrosine (C28Y) or alanine (C28A) for the tryptophan residue lowered the affinity for calmodulin. The estimated Kd values for the calmodulin-peptide complexes were 0.1 nM for C28W, 5-15 nM for C20W, C28Y, and C28A, and 700-1700 nM for C15W. The Ca2+ pump in inside-out erythrocyte membrane vesicles was activated by proteolytic removal of the endogenous calmodulin-binding domain. Addition of C20W or C28W then inhibited calmodulin-independent Ca2+ transport, while a calmodulin-binding peptide from another enzyme had no effect. The inhibition of the pump by C20W was purely competitive with Ca2+, while C28W decreased the Vmax and increased the K1/2 for Ca2+, restoring the pump activity nearly to its low basal level. The results suggest that a calmodulin-binding peptide from any enzyme has two kinds of specificity: it shares with peptides from other enzymes the ability to bind to calmodulin, but only it has the specificity to interact with its own (proteolytically activated) enzyme.  相似文献   

15.
Tryptophan (Trp) residues play important roles in many proteins. In particular they are enriched in protein surfaces involved in protein docking and are often found in membrane proteins close to the lipid head groups. However, they are usually absent from the membrane domains of mechanosensitive channels. Three Trp residues occur naturally in the Escherichia coli MscS (MscS-Ec) protein: W16 lies in the periplasm, immediately before the first transmembrane span (TM1), whereas W240 and W251 lie at the subunit interfaces that create the cytoplasmic vestibule portals. The role of these residues in MscS function and stability were investigated using site-directed mutagenesis. Functional channels with altered properties were created when any of the Trp residues were replaced by another amino acid, with the greatest retention of function associated with phenylalanine (Phe) substitutions. Analysis of the fluorescence properties of purified mutant MscS proteins containing single Trp residues revealed that W16 and W251 are relatively inaccessible, whereas W240 is accessible to quenching agents. The data point to a significant role for W16 in the gating of MscS, and an essential role for W240 in MscS oligomer stability.  相似文献   

16.
The Mentalities of Gorillas and Orangutans: Comparative Perspectives. Sue Taylor Parker. Robert W. Mitchell. and H. Lyn Miles. eds. New York: Cambridge University Press, 1999. 419 pp.  相似文献   

17.
The Thread of Life: Toraja Reflections on the Life Cycle. Douglas W. Hollan and Jane C. Wellenkamp. Honolulu: University of Hawaii Press, 1996. 239 pp.  相似文献   

18.
The Osteology of Infants and Children . Brenda J. Baker, Tosha L. Dupras, and Matthew W. Tocheri. College Station: Texas A&M University Press, 2005. 178 pp.  相似文献   

19.
Summary 1047 healthy, random blood donors were typed independently for HL-A antigens by platelet complement fixation and lymphocytotoxicity. The results of both methods were analyzed statistically and the gene frequencies calculated. The gene frequencies were: first HL-A locus: 1: 0.1277–0.1316; 2: 0.3018–0.3053; 3: 0.1411–0.1456; 9: 0.1061–0.1088; 10: 0.0540–0.0564; 11: 0.0381–0.0416; W28: 0.0096–0.0271; W32: 0.0365–0.0469; second HL-A locus: 5: 0.0613–0.0649; 7: 0.1367–0.1401; 8: 0.0716–0.0920; 12: 0.0383–0.0903; 13: 0.0357–0.0371; W5: 0.0786–0.0844; W10: 0.0594–0.0620; W14: 0.0280–0.0315; W15: 0.0650–0.0722; W17: 0.0399; W18: 0.0241–0.0374; W22: 0.0037–0.0161; W27: 0.0406–0.0532; W21: 0.0329–0.0428. The discrepancies of typing results are discussed and their practical importance for paternity serology is stressed.Supported by the Deutsche Forschungsgemeinschaft (Mu 277/5).  相似文献   

20.
Objective: Implied in measures of binge eating is the assumption that individuals agree on what comprises a large amount of food. However, whether individuals estimate food amounts similarly or whether estimation of food amounts varies as a function of personal characteristics is unknown. The Food Amount Rating Scale (FARS) is a standardized set of stimuli for assessing individuals’ judgment of food amounts. Research Methods and Procedures: Two versions of the FARS were developed, and their psychometric properties were assessed. These versions are the same in all respects except that the rater is instructed to rate various food amounts for the average woman on Form W and for the average man on Form M. Results: Content validity was confirmed by 14 researchers and research assistants in the field of eating disorders. The FARS is a 24-item inventory with adequate test–retest reliability (Form W = 0.85; Form M = 0.87) and split–half reliability (Form W = 0.90; Form M = 0.89). Convergent validity is suggested by the finding that ratings for the average woman (Form W) were significantly higher than ratings for the average man (Form M). Discussion: The FARS is a psychometrically sound tool for use in basic research focused on identifying whether the subjective judgment of food amounts varies as a function of personal characteristics and in clinical research where it may be important to know how individuals judge food amounts.  相似文献   

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