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81.
Shi J Ebrik MA Yang B Garlock RJ Balan V Dale BE Pallapolu VR Lee YY Kim Y Mosier NS Ladisch MR Holtzapple MT Falls M Sierra-Ramirez R Donohoe BS Vinzant TB Elander RT Hames B Thomas S Warner RE Wyman CE 《Bioresource technology》2011,102(24):11080-11088
Accellerase 1000 cellulase, Spezyme CP cellulase, β-glucosidase, Multifect xylanase, and beta-xylosidase were evaluated for hydrolysis of pure cellulose, pure xylan, and switchgrass solids from leading pretreatments of dilute sulfuric acid, sulfur dioxide, liquid hot water, lime, soaking in aqueous ammonia, and ammonia fiber expansion. Distinctive sugar release patterns were observed from Avicel, phosphoric acid swollen cellulose (PASC), xylan, and pretreated switchgrass solids, with accumulation of significant amounts of xylooligomers during xylan hydrolysis. The strong inhibition of cellulose hydrolysis by xylooligomers could be partially attributed to the negative impact of xylooligomers on cellulase adsorption. The digestibility of pretreated switchgrass varied with pretreatment but could not be consistently correlated to xylan, lignin, or acetyl removal. Initial hydrolysis rates did correlate well with cellulase adsorption capacities for all pretreatments except lime, but more investigation is needed to relate this behavior to physical and compositional properties of pretreated switchgrass. 相似文献
82.
Veronica Vinciotti Xiaohui Liu Rolf Turk Emile J de Meijer Peter AC 't Hoen 《BMC bioinformatics》2006,7(1):183-12
Background
The identification of biologically interesting genes in a temporal expression profiling dataset is challenging and complicated by high levels of experimental noise. Most statistical methods used in the literature do not fully exploit the temporal ordering in the dataset and are not suited to the case where temporal profiles are measured for a number of different biological conditions. We present a statistical test that makes explicit use of the temporal order in the data by fitting polynomial functions to the temporal profile of each gene and for each biological condition. A Hotelling T 2-statistic is derived to detect the genes for which the parameters of these polynomials are significantly different from each other. 相似文献83.
84.
Michael C. Mosier Franklin A. Graybill 《Biometrical journal. Biometrische Zeitschrift》1995,37(3):273-297
When conducting a statistical analysis of data from a designed experiment, an investigator is often interested in confidence intervals for contrasts of the fixed effects. If the analysis involves a mixed linear model, exact confidence intervals for contrasts of the fixed effects are not always available. In such cases, confidence intervals with approximate coverage probabilities must be used. As will be shown, this problem may be generalized to that of constructing a confidence interval for the parameter μ, where X is a normal random variable with mean μ and variance ∑ aqθq, where a1…,aQ are known constants, Uq = nqS/θq is a chi-squared random variable with nq degrees of freedom, for each q = 1,…, Q, and X,U1,…, UQ are mutually independent. In this paper, we consider the case where Q = 3 and a3 ≤0. 相似文献
85.
A covariotide model explains apparent phylogenetic structure of oxygenic photosynthetic lineages 总被引:17,自引:13,他引:4
Lockhart PJ; Steel MA; Barbrook AC; Huson DH; Charleston MA; Howe CJ 《Molecular biology and evolution》1998,15(9):1183-1188
The aims of the work were (1) to develop statistical tests to identify
whether substitution takes place under a covariotide model in sequences
used for phylogenetic inference and (2) to determine the influence of
covariotide substitution on phylogenetic trees inferred for photosynthetic
and other organisms. (Covariotide and covarion models are ones in which
sites that are variable in some parts of the underlying tree are invariable
in others and vice versa.) Two tests were developed. The first was a
contingency test, and the second was an inequality test comparing the
expected number of variable sites in two groups with the observed number.
Application of these tests to 16S rDNA and tufA sequences from a range of
nonphotosynthetic prokaryotes and oxygenic photosynthetic prokaryotes and
eukaryotes suggests the occurrence of a covariotide mechanism. The degree
of support for partitioning of taxa in reconstructed trees involving these
organisms was determined in the presence or absence of sites showing
particular substitution patterns. This analysis showed that the support for
splits between (1) photosynthetic eukaryotes and prokaryotes and (2)
photosynthetic and nonphotosynthetic organisms could be accounted for by
patterns arising from covariotide substitution. We show that the additional
problem of compositional bias in sequence data needs to be considered in
the context of patterns of covariotide/covarion substitution. We argue that
while covariotide or covarion substitution may give rise to
phylogenetically informative patterns in sequence data, this may not always
be so.
相似文献
86.
Simplified method for recovery and PCR detection of Cryptosporidium DNA from bovine feces. 总被引:6,自引:2,他引:4
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An assay to identify Cryptosporidium DNA in bovine feces has been developed emphasizing standardization of sample preparation and simplification of the DNA recovery process for PCR amplification and DNA hybridization detection. The Cryptosporidium DNA recovery-PCR detection procedure (CR-PCR) can recover DNA suitable for PCR amplification without using or generating hazardous chemicals or wastes. In comparisons with a commercial enzyme-linked immunoassay (Color Vue-Cryptosporidium; Seradyn, Indianapolis, Ind.), the CR-PCR could detect 10(3) to 10(4) times fewer purified oocysts diluted in solution (water or buffered saline) and 10(2) times fewer oocysts from diarrheic feces and showed earlier detectability from solid, nondiarrheic feces in an experimental infection. This assay may prove useful for detecting Cryptosporidium oocysts in feces and in clarifying the role of livestock in waterborne outbreaks of cryptosporidiosis. 相似文献
87.
Nitrogen (N) availability is a key role in food and fiber production. Providing plant-available N through synthetic fertilizer in the 20th and early 21st century has been a major contributor to the increased production required to feed and clothe the growing human population. To continue to meet the global demands and to minimize environmental problems, significant improvements are needed in the efficiency with which fertilizer N is utilized within production systems. There are still major uncertainties regarding the fate of fertilizer N added to agricultural soils and the potential for reducing losses to the environment. Enhancing the technical and economic efficiency of fertilizer N is seen to promote a favorable situation for both agricultural production and the environment, and this has provided much of the impetus for a new N fertilizer project.To address this important issue, a rapid assessment project on N fertilizer (NFRAP) was conducted by SCOPE (the Scientific Committee on Problems of the Environment) during late 2003 and early 2004. This was the first formal project of the International Nitrogen Initiative (INI). As part of this assessment, a successful international workshop was held in Kampala, Uganda on 12 –16 January, 2004. This workshop brought together scientists from around the world to assess the fate of synthetic fertilizer N in the context of overall N inputs to agricultural systems, with a view to enhancing the efficiency of N use and reducing negative impacts on the environment. Regionalization of the assessment highlighted the problems of too little N for crop production to meet the nutrient requirements of sub-Saharan Africa and the oversupply of N in the major rice-growing areas of China. The results of the assessment are presented in a book (SCOPE 65) which is now available to provide a basis for further discussions on N fertilizer. 相似文献
88.
Data from population- and clinic-based epidemiologic studies of rheumatoid arthritis patients suggest that individuals with
rheumatoid arthritis are at risk for developing clinically evident congestive heart failure. Many established risk factors
for congestive heart failure are over-represented in rheumatoid arthritis and likely account for some of the increased risk
observed. In particular, data from animal models of cytokine-induced congestive heart failure have implicated the same inflammatory
cytokines produced in abundance by rheumatoid synovium as the driving force behind maladaptive processes in the myocardium
leading to congestive heart failure. At present, however, the direct effects of inflammatory cytokines (and rheumatoid arthritis
therapies) on the myocardia of rheumatoid arthritis patients are incompletely understood. 相似文献
89.
Yan F Mosier PD Westkaemper RB Stewart J Zjawiony JK Vortherms TA Sheffler DJ Roth BL 《Biochemistry》2005,44(24):8643-8651
Salvinorin A is a naturally occurring hallucinogenic diterpenoid from the plant Salvia divinorumthat selectively and potently activates kappa-opioid receptors (KORs). Salvinorin A is unique in that it is the only known lipid-like molecule that selectively and potently activates a G-protein coupled receptor (GPCR), which has as its endogenous agonist a peptide; salvinorin A is also the only known non-nitrogenous opioid receptor agonist. In this paper, we identify key residues in KORs responsible for the high binding affinity and agonist efficacy of salvinorin A. Surprisingly, we discovered that salvinorin A was stabilized in the binding pocket by interactions with tyrosine residues in helix 7 (Tyr313 and Tyr320) and helix 2 (Tyr119). Intriguingly, activation of KORs by salvinorin A required interactions with the helix 7 tyrosines Tyr312, Tyr313, and Tyr320 and with Tyr139 in helix 3. In contrast, the prototypical nitrogenous KOR agonist U69593 and the endogenous peptidergic agonist dynorphin A (1-13) showed differential requirements for these three residues for binding and activation. We also employed a novel approach, whereby we examined the effects of cysteine-substitution mutagenesis on the binding of salvinorin A and an analogue with a free sulfhydryl group, 2-thiosalvinorin B. We discovered that residues predicted to be in close proximity, especially Tyr313, to the free thiol of 2-thiosalvinorin B when mutated to Cys showed enhanced affinity for 2-thiosalvinorin B. When these findings are taken together, they imply that the diterpenoid salvinorin A utilizes unique residues within a commonly shared binding pocket to selectively activate KORs. 相似文献
90.
Determinants of Readiness for Adopting Healthy Lifestyle Behaviors Among Indigenous Adolescents with Type 2 Diabetes in Manitoba,Canada: A Cross‐Sectional Study
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