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941.
Andrew J. Ghio 《Biometals》2016,29(5):751-779
Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam’s razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e.g. asthma associated with infections, smoking, and obesity). Comparable associations between asthma co-morbidity (e.g. eczema, urticaria, restless leg syndrome, and pulmonary hypertension) with iron deficiency support such a shared mechanistic pathway. Therapies directed at asthma demonstrate a capacity to impact iron homeostasis, further strengthening the relationship. Finally, pathophysiologic events producing asthma, including inflammation, increases in Th2 cells, and muscle contraction, can correlate with iron availability. Recognition of a potential association between asthma and an absolute and/or functional iron deficiency suggests specific therapeutic interventions including inhaled iron. 相似文献
942.
This article explores responses to the implementation of Russian sturgeon conservation policy in three fishing communities (in Dagestan, Kalmykia and the Volga River delta areas), along the Western and Northern coasts of the Caspian Sea. Enforcement of regulatory measures has led to complex socio-cultural responses. We show how social responses to conservation policy generate various forms of poaching. An analytical model of ‘soft’ and ‘hard’ forms of poaching is analyzed against three regulatory measures: introduction of specially designated fishing areas in Russia’s Caspian fisheries, border zone expansion and the ban on sturgeon fishing. We explain why in Kalmykia the policy led people to stop practicing hard forms of sturgeon fishing, while fishermen in Dagestan responded in a more complex manner by displaying resistance towards the new policies. 相似文献
943.
944.
945.
Rui-Cin Lyu Hui-Yu Hu Lih-Ying Kuo Huei-Fen Lo Ping-Lin Ong Hui-Ping Chang Long-Liu Lin 《Current microbiology》2009,59(2):101-106
Role of the conserved Thr399 and Thr417 residues of Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT) was investigated by site-directed mutagenesis. Substitutions of Thr399 and Thr417 of BlGGT with Ser resulted in a dramatic reduction in enzymatic activity. A complete loss of the GGT activity was observed in T399A,
T399C, T417A, and T417K mutant enzymes. Furthermore, mutations on these two residues impaired the capability of autocatalytic
processing of the enzyme. In vitro maturation experiments showed that BlGGT mutant precursors, pro-T399S, pro-T417S, and pro-T417A, could precede a time-dependent autocatalytic process to generate
the 44.9- and 21.7-kDa subunits; however, the processed T417A had no enzymatic activity. Measurement of intrinsic tryptophan
fluorescence revealed alteration of the microenvironment of aromatic amino acid residues, while Far-UV circular dichroism
spectra were nearly identical for wild-type and mutant enzymes. These results suggest that residues Thr399 and Thr417 are
important for BlGGT in the enzymatic maturation and reaction.
An erratum to this article can be found at 相似文献
946.
Zhuang Kang Jia-hong Jiang Dong Wang Ke Liu Lin-fang Du 《Biochemistry. Biokhimii?a》2009,74(1):102-109
The trypsin inhibitor SOTI was isolated from Spinacia oleracea L. seeds through ammonium sulfate precipitation, Sepharose 4B-trypsin affinity chromatography, and Sephadex G-75 chromatography.
This typical Kunitz inhibitor showed remarkable stability to heat, pH, and denaturant. It retained 80% of its activity against
trypsin after boiling for 20 min, and more than 90% activity when treated with 6 M guanidine hydrochloride. The formation
of stable SOTI-trypsin complex (K
i
= 2.3·10−6 M) is consistent with significant inhibitory activity of SOTI against trypsin-like proteinases present in the larval midgut
of Pieris rapae. Sequences of SOTI fragments showed homology with other inhibitors.
Published in Russian in Biokhimiya, 2009, Vol. 74, No. 1, pp. 131–140. 相似文献
947.
Mutation analysis of the cystic fibrosis transmembrane regulator gene in native American populations of the southwest 下载免费PDF全文
Theresa A. Grebe Winifred W. Doane Sarah F. Richter Carol Clericuzio R. A. Norman William K. Seltzer Susan N. Rhodes Bruce E. Goldberg Lucy S. Hernried Melody McClure Gail Kaplan 《American journal of human genetics》1992,51(4):736-740
We report DNA and clinical analyses of cystic fibrosis (CF) in two previously unstudied, genetically isolated populations: Pueblo and Navajo Native Americans. Direct mutation analysis of six mutations of the CFTR gene--namely, delta F508, G542X, G551D, R553X, N1303K, and W1282X--was performed on PCR-amplified genomic DNA extracted from blood samples. Haplotype analyses with marker/enzyme pairs XV2c/TaqI and KM19/PstI were performed as well. Of the 12 affected individuals studied, no delta F508 mutation was detected; only one G542X mutation was found. None of the other mutations was detected. All affected individuals have either an AA, AC, or CC haplotype, except for the one carrying the G542X mutation, who has the haplotype AB. Clinically, six of the affected individuals examined exhibit growth deficiency, and five (all from the Zuni Pueblo) have a severe CF phenotype. Four of the six Zunis with CF are also microcephalic, a finding not previously noted in CF patients. Our DNA data have serious implications for risk assessment of CF carrier status for these people. 相似文献
948.
Daryl E. Enstone Carol A. Peterson Fengshan Ma 《Journal of Plant Growth Regulation》2002,21(4):335-351
Roots of virtually all vascular plants have an endodermis with a Casparian band, and the majority of angiosperm roots tested also have an exodermis with a Casparian band. Both the endodermis and exodermis may develop suberin lamellae and thick, tertiary walls. Each of these wall modifications has its own function(s). The endodermal Casparian band prevents the unimpeded movement of apoplastic substances into the stele and also prevents the backflow of ions that have moved into the stele symplastically and then were released into its apoplast. In roots with a mature exodermis, the barrier to apoplastic inflow of ions occurs near the root surface, but prevention of backflow of ions from the stele remains a function of the endodermis. The suberin lamellae protect against pathogen invasion and possibly root drying during times of stress. Tertiary walls of the endodermis and exodermis are believed to function in mechanical support of the root, but this idea remains to be tested. During stress, root growth rates decline, and the endodermis and exodermis develop closer to the root tip. In two cases, stress is known to induce the formation of an exodermis, and in several other cases to accelerate the development of both the exodermis and endodermis. The responses of the endodermis and exodermis to drought, exposure to moist air, flooding, salinity, ion deficiency, acidity, and mechanical impedance are discussed. 相似文献
949.
Rhodococcus sp. strain JVH1 was previously reported to use a number of compounds with aliphatic sulfide bridges as sulfur sources for
growth. We have shown that although JVH1 does not use the three-ring thiophenic sulfur compound dibenzothiophene, this strain
can use the two-ring compound benzothiophene as its sole sulfur source, resulting in growth of the culture and loss of benzothiophene.
Addition of inorganic sulfate to the medium reduced the conversion of benzothiophene, indicating that benzothiophene metabolism
is repressed by sulfate and that benzothiophene is therefore used specifically as a sulfur source. JVH1 also used all six
isomers of methylbenzothiophene and two dimethylbenzothiophene isomers as sulfur sources for growth. Metabolites identified
from benzothiophene and some methylbenzothiophenes were consistent with published pathways for benzothiophene biodesulfurization.
Products retaining the sulfur atom were sulfones and sultines, the sultines being formed from phenolic sulfinates under acidic
extraction conditions. With 2-methylbenzothiophene, the final desulfurized product was 2-methylbenzofuran, formed by dehydration
of 3-(o-hydroxyphenyl) propanone under acidic extraction conditions and indicating an oxygenative desulfination reaction. With 3-methylbenzothiophene,
the final desulfurized product was 2-isopropenylphenol, indicating a hydrolytic desulfination reaction. JVH1 is the first
microorganism reported to use all six isomers of methylbenzothiophene, as well as some dimethylbenzothiophene isomers, as
sole sulfur sources. JVH1 therefore possesses broader sulfur extraction abilities than previously reported, including not
only sulfidic compounds but also some thiophenic species. 相似文献
950.
Walter J Loach DM Alqumber M Rockel C Hermann C Pfitzenmaier M Tannock GW 《Environmental microbiology》2007,9(7):1750-1760
The dlt operon of Gram-positive bacteria encodes proteins required for the incorporation of D-alanine esters into cell wall-associated teichoic acids (TA). D-alanylation of TA has been shown to be important for acid tolerance, resistance to antimicrobial peptides, adhesion, biofilm formation, and virulence of a variety of pathogenic organisms. The aim of this study was to determine the importance of D-alanylation for colonization of the gastrointestinal tract by Lactobacillus reuteri 100-23. Insertional inactivation of the dltA gene resulted in complete depletion of D-alanine substitution of lipoteichoic acids. The dlt mutant had similar growth characteristics as the wild type under standard in vitro conditions, but formed lower population sizes in the gastrointestinal tract of ex-Lactobacillus-free mice, and was almost eliminated from the habitat in competition experiments with the parental strain. In contrast to the wild type, the dlt mutant was unable to form a biofilm on the forestomach epithelium during gut colonization. Transmission electron microscope observations showed evidence of cell wall damage of mutant bacteria present in the forestomach. The dlt mutant had impaired growth under acidic culture conditions and increased susceptibility to the cationic peptide nisin relative to the wild type. Ex vivo adherence of the dlt mutant to the forestomach epithelium was not impaired. This study showed that D-alanylation is an important cell function of L. reuteri that seems to protect this commensal organism against the hostile conditions prevailing in the murine forestomach. 相似文献