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排序方式: 共有171条查询结果,搜索用时 177 毫秒
91.
L.A. Krueger M.A. Grzemski M.C. Bilyeu J.G. Horst S.A. Ugrin C.A. Hosette D.A. Spangler G.A. Ayangbile 《Letters in applied microbiology》2020,71(5):550-556
A series of experiments was conducted to identify the molecular species responsible for surface active emulsification (surfactant) bioactivity in Bacillus subtilis subsp. subtilis strain ATCC PTA-125135, and to describe culture conditions to support the enriched production of said bioactivity in cultured plaque of the strain. The assay for methylene blue active substances (MBAS) was found to be suitable for describing surfactant activity, where a solvent-extracted molecular fraction from the biofilm was found to retain surfactant activity and positively quantified as MBAS. Furthermore, an HPLC-refined protein fraction was found to quantify as MBAS with approximately 1·36-fold or greater surfactant activity per mol than sodium dodecyl sulphate, and a proteomic analysis of solvent extracted residues confirmed that biofilm surface layer protein BslA was a primary constituent of extracted residues. Surfactant bioactivity, quantified as MBAS, was enriched in cultured plaque by the supplementation of culture media with calcium chloride or calcium nitrate. 相似文献
92.
Venkata Ramana Lakkaraju Xiaobing Zhou Martha E. Apple Al Cunningham Laura M. Dobeck Kadie Gullickson Lee H. Spangler 《Ecological Informatics》2010,5(5):379-389
Measurement of spectral reflectance provides a fast and nondestructive method of stress detection in vegetation. In this shallow subsurface CO2 release experiment to simulate CO2 leakage of geologically sequestered CO2, the radiometric responses of plants to elevated soil CO2 concentration were monitored using a spectroradiometer. Spectral responses included increased reflectance in the visible spectral region and decreased reflectance in the near-infrared region and thus an altered spectral pattern of vegetation. Visible responses of vegetation include purple discoloration and eventual death of leaves at sites where the soil CO2 concentration was very high. Derivative analysis identified two features (minimum and maximum) in the 575–580 nm and 720–723 nm spectral regions. The normalized difference first derivative index (NFDI) was defined based on the spectral derivative at the two bands. Four vegetation indices were analyzed with the accumulated soil CO2 concentration to assess the accumulated impact of high soil CO2 concentration on vegetation. Results show that with increased soil CO2 concentration due to the surface CO2 leakage, (1) the structural independent pigment index (SIPI) increased, indicating a high carotenoid to chlorophyll ratio; (2) the chlorophyll normalized difference vegetation index (Chl NDI) decreased, suggesting a decrease in chlorophyll content with time; (3) pigment specific simple ratios (both PSSRa and PSSRb) were reduced for stressed vegetation compared to that at the control site, indicating a reduction in both chlorophyll a and chlorophyll b; and (4) NFDI was low where plants were stressed. Changes in NFDI during the experiment were 36% and 1% for stressed and control plants, respectively. All four indices were found to be sensitive to stress in vegetation induced by high soil CO2 concentration. 相似文献
93.
Gloria DeGrandi-Hoffman Anita Collins Joseph H. Martin Justin O. Schmidt Hayward G. Spangler 《Journal of Insect Behavior》1998,11(1):37-45
Honey bee (Apis mellifera L.) colonies with either European or Africanized queens mated to European or Africanized drones alone or in combination were tested for defensive behavior using a breath test. The most defensive colonies were those with European or Africanized queens mated to Africanized drones. In colonies where both European and Africanized patrilines existed, most of the workers participating in nest defense behavior for the first 30 s after a disturbance were of African patrilines. Nest defense behavior appears to be genetically dominant in honey bees. 相似文献
94.
Kerstin Y. Beste Corinna M. Spangler Heike Burhenne Karl-Wilhelm Koch Yuequan Shen Wei-Jen Tang Volkhard Kaever Roland Seifert 《PloS one》2013,8(7)
Guanylyl cyclases (GCs) regulate many physiological processes by catalyzing the synthesis of the second messenger cGMP. The GC family consists of seven particulate GCs (pGCs) and a nitric oxide-activated soluble GC (sGC). Rat sGC α1β1 possesses much broader substrate specificity than previously assumed. Moreover, the exotoxins CyaA from Bordetella pertussis and edema factor (EF) from Bacillus anthracis possess nucleotidyl cyclase (NC) activity. pGC-A is a natriuretic peptide-activated homodimer with two catalytic sites that act cooperatively. Here, we studied the NC activity of rat pGC-A in membranes of stably transfected HEK293 cells using a highly sensitive and specific HPLC-MS/MS technique. GTP and ITP were effective, and ATP and XTP were only poor, pGC-A substrates. In contrast to sGC, pGC-A did not use CTP and UTP as substrates. pGC-E and pGC-F expressed in bovine rod outer segment membranes used only GTP as substrate. In intact HEK293 cells, pGC-A generated only cGMP. In contrast to pGCs, EF and CyaA showed very broad substrate-specificity. In conclusion, NCs exhibit different substrate-specificities, arguing against substrate-leakiness of enzymes and pointing to distinct physiological functions of cyclic purine and pyrimidine nucleotides. 相似文献
95.
96.
Change is a fundamental component of contemporary restoration ecology. The environment, the research, and the ideas in this discipline are rapidly evolving and changing. The California Society for Ecological Restoration annual meeting was an inclusive, diverse meeting that significantly advanced new thinking in the field and provided an exemplar of the value of scientific discourse at meetings. The restoration work in this region also amplified and identified trends in the scientific community at large. A total of three future‐oriented strategic issues emerged from the discourse at this meeting. (1) Restoration ecologists need to consider alternative definitions of local for interventions within a region. (2) Restoration is never complete and must always incorporate people. (3) Indirect outcomes and the process of restoration have merit despite challenges of immediate identification of benefits. The science presented served as a platform for these advanced strategic issue examinations, and the grandest of challenges for restoration ecology necessarily includes people in every equation and embraces values and perceptions over longer time frames. 相似文献
97.
Binding to native proteins by antipeptide monoclonal antibodies 总被引:3,自引:0,他引:3
B D Spangler 《Journal of immunology (Baltimore, Md. : 1950)》1991,146(5):1591-1595
mAb raised against synthetic peptides derived from cholera toxin, myohemerythrin, and sickle hemoglobin were analyzed by both solid-phase and solution-phase methods. Antipeptide mAb against cholera toxin (mAb TE32 and TE33), against myohemerythrin (mAb B13I2, B13C2, and B13F2), and against sickle hemoglobin (mAb HuS-1 and HuS-2), had been previously described and used for vaccine development, structural characterization, or identification of a specific antigenic determinant, and each was apparently capable of binding both peptide and native Ag. In this study, all were found to bind whole protein when tested against immobilized Ag in a standard solid-phase assay (ELISA), yet none of the antibodies recognized the Ag in its true native form, failing to bind when tested in several solution-phase assay systems, including size exclusion HPLC. This discrepancy may be the result of modifications of the epitope created by interaction and possible denaturation of the protein on the solid-phase matrix. As a consequence, binding of these antibodies to peptides, either immobilized or in solution, or to immobilized protein, cannot be used to infer that the peptide has assumed a conformation that corresponds to that of the cognate sequence in the native protein. A re-evaluation of binding data that relates antipeptide mAb to native structural characteristics may be necessary. 相似文献
98.
99.
Ismayil Ahmet Edward Spangler Barbara Shukitt-Hale James A. Joseph Donald K. Ingram Mark Talan 《PloS one》2009,4(11)
Background
Despite remarkable progress in treatment of chronic heart failure (CHF) over the last two decades, mortality, personal suffering and cost remain staggering, and effective interventions are still a challenge. Previously we reported that a blueberry-enriched diet (BD) attenuated necroapoptosis and inflammation in periinfarct area in a rat model of myocardial infarction (MI).Objectives
To test the hypothesis that BD will attenuate the course of CHF, including mortality and cardiac remodeling during the first year after induction of MI in rats.Method and Results
Two weeks after coronary artery ligation, rats were divided into two groups of similar average MI size, measured by echocardiography, and then12-mo dietary regimens were initiated as follows: ad libitum regular diet (control, CD, n = 27) and isocaloric food with 2% blueberry supplement (BD, n = 27) also available ad libitum. These dietary groups were compared to each other and to sham group (SH). Mortality over the 12 mo was reduced by 22% in BD compared with CD (p<0.01). In the course of developing CHF, BD had no effect on the body weight, heart rate or blood pressure. Bi-monthly Echo revealed significant attenuation of the LV chamber remodeling, LV posterior wall thinning, and MI expansion in BD compared with CD. In fact, BD arrested the MI expansion.Conclusion
This is the first experimental evidence that a blueberry-enriched diet has positive effects on the course of CHF and thus warrants consideration for clinical evaluation. 相似文献100.
Diversity, Distribution, and Ancient Taxonomic Relationships Within the TIR and Non-TIR NBS-LRR Resistance Gene Subfamilies 总被引:1,自引:0,他引:1
Cannon SB Zhu H Baumgarten AM Spangler R May G Cook DR Young ND 《Journal of molecular evolution》2002,54(4):548-562
Phylogenetic relationships among the NBS-LRR (nucleotide binding site–leucine-rich repeat) resistance gene homologues (RGHs)
from 30 genera and nine families were evaluated relative to phylogenies for these taxa. More than 800 NBS-LRR RGHs were analyzed,
primarily from Fabaceae, Brassicaceae, Poaceae, and Solanaceae species, but also from representatives of other angiosperm
and gymnosperm families. Parsimony, maximum likelihood, and distance methods were used to classify these RGHs relative to
previously observed gene subfamilies as well as within more closely related sequence clades. Grouping sequences using a distance
cutoff of 250 PAM units (point accepted mutations per 100 residues) identified at least five ancient sequence clades with
representatives from several plant families: the previously observed TIR gene subfamily and a minimum of four deep splits
within the non-TIR gene subfamily. The deep splits in the non-TIR subfamily are also reflected in comparisons of amino acid
substitution rates in various species and in ratios of nonsynonymous-to-synonymous nucleotide substitution rates (K
A/K
S values) in Arabidopsis thaliana. Lower K
A/K
S values in the TIR than the non-TIR sequences suggest greater functional constraints in the TIR subfamily. At least three
of the five identified ancient clades appear to predate the angiosperm–gymnosperm radiation. Monocot sequences are absent
from the TIR subfamily, as observed in previous studies. In both subfamilies, clades with sequences separated by approximately
150 PAM units are family but not genus specific, providing a rough measure of minimum dates for the first diversification
event within these clades. Within any one clade, particular taxa may be dramatically over- or underrepresented, suggesting
preferential expansions or losses of certain RGH types within particular taxa and suggesting that no one species will provide
models for all major sequence types in other taxa.
Received: 13 June 2001 / Accepted: 22 October 2001 相似文献