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排序方式: 共有113条查询结果,搜索用时 15 毫秒
1.
Comparison of Rumen Microbial Inhibition Resulting from Various Essential Oils Isolated from Relatively Unpalatable Plant Species 总被引:2,自引:0,他引:2
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Essential oils were isolated from eight plant species which were relatively unpalatable to sheep and deer. The inhibitory potency of these essential oils upon sheep and deer rumen microorganisms was compared, in terms of total gas and volatile fatty acid (VFA) production, by use of an anaerobic manometric technique. Inhibitory effects of oils from the eight plant species may be placed in four groups: (i) essential oils from vinegar weed (Trichostema lanceoletum) and California bay (Umbellularia californica) inhibited rumen microbial activity most; (ii) lesser inhibition was exhibited by rosemary (Rosmarinus officinalis) and California mugwort (Artemisia douglasiana) oils, followed by (iii) blue-gum eucalyptus (Eucalyptus globulus) and sagebrush (Artemisia tridentata) oils; and (iv) oils from Douglas fir (Psuedotsuga menziesii) and Jerusalem oak (chenopodium botrys) resulted in the least inhibition, when 0.3 ml of each oil was used. A highly significant correlation coefficient (r = 0.98(**)) between total gas and VFA production indicated the validity of either method to measure the activity of rumen microorganisms. Our results are discussed in relation to the hypothesis that the selectivity and voluntary consumption of ruminants are related to the characteristic odor and antibacterial action of essential oils isolated from relatively unpalatable plant species. 相似文献
2.
Donald J. Brasch Hi Mui Chang Chaw T. Chuah Laurence D. Melton 《Carbohydrate research》1981,97(1):113-125
A galactan sulfate has been isolated from the seaweed Porphyra columbina, and its structure established by a combination of methylation, methanolysis, treatment with alkali followed by methylation, and 13C-n.m.r. spectroscopy. The polysaccharide belongs to the porphyran class, and consists of 3-linked β-d-galactosyl residues and 4-linked α-l-galactosyl residues. 3,6-Anhydro-l-galactose and l-galactose 6-sulfate residues total approximately half of the sugar units, the other half being made up of d-galactose and 6-O-methyl-d-galactose residues. Some evidence is presented that suggests that the galactan sulfate does not have a completely alternating structure. 相似文献
3.
Song Hi Lee 《Molecular simulation》2013,39(18):1498-1505
ABSTRACTIn this paper, we have extended our previous study of the static and dynamic properties (self-diffusion coefficient Dself and friction coefficient ζ) of liquid n-alkane systems up C400 at several temperatures (~2300?K) using molecular dynamics (MD) simulations in the canonical ensembles. For the small n-alkanes with n?≤?120 (n: the chain length), the chains are clearly ?R2 ee?/6?R2 g? ≥ 1 (1.06 ~ 1.44), which leads to the conclusion that the liquid n-alkanes are far away from the ideal chain regime. But for the n-alkanes of n?≥?160, the chains are ?R2 ee?/6?R2 g? ≈ 1, indicating that they are Gaussian. It is found that the long chains of these n-alkanes at high temperatures show abnormalities in density and friction coefficient. We observed a clear transition in the power law dependence of n-alkane self-diffusion coefficient on the molecular weight (M) of n-alkane, Dself ~ M?γ, occurs in the range C120~C160 at temperatures of 318, and 618?K, corresponding to a crossover from the ‘oligomer’ to the ‘Rouse’ regime. The entanglement lengths (Ne) are calculated by the Z1 code and discussed shortly. 相似文献
4.
Song Hi Lee 《Molecular simulation》2013,39(11):895-901
We present the results of molecular dynamics simulations for alkali earth metal cations (Mg2+, Ca2+, Sr2+ and Ba2+) in an aqueous solution at 25°C using the extended simple point charge water potential with Ewald summation. The ion mobilities (defined by ui = DiziF/RT) obtained from the simulations are in good accord with the experimental measures. The strong divalent cation–water interactions explain well the static and dynamic properties of the alkali earth metal cations. The classical solvent-berg picture describes the ion mobilities of these cations in water adequately. 相似文献
5.
Acetic acid is by-product from fermentation processes for producing succinic acid using Mannheimia succiniciproducens . To obtain pure succinic acid from the final fermentation broth, acetic acid was selectively removed based on the different extractability of succinic acid and acetic acid with pH using tri-n-octylamine (TOA) as extractant. When successive batch extractions were performed using 0.25 mol TOA kg(-1) dissolved in 1-octanol at pH 5, the mol ratio of succinic acid to acetic acid before extraction was 4.9 and the final ratio after the fourth batch was 9.4. 相似文献
6.
7.
This study was conducted to investigate how different levels of illumination below 1,000 lx would affect the autonomic and behavioral temperature regulation of humans. Seven healthy college-aged women (20+/-0 years) volunteered to participate in this study. They were exposed to a temperature of 26 degrees C in 320 lx for 30 min ('Equilibrium') followed by 700 lx or 70 lx for 30 min (stage 1). After stage 1, they were exposed to 20 degrees C for 30 min in the same illumination as in stage 1 (stage 2). In stage 2 the subjects were instructed to select and wear the clothing they needed for their thermal comfort. The data obtained were analyzed by paired t-test and repeated measures of analysis of variance. Forearm skin blood flow tended to remain steady in 700 lx but decreased markedly in 70 lx in stage 1. There were no significant differences between subjective thermal responses of the subjects experiencing 700 lx or 70 lx in both stages although the subjects felt cooler in stage 2 than in stage 1. The subjects were likely to prefer wearing heavier clothing in 70 lx than in 700 lx. It was concluded that vasoconstriction in the upper limbs occurred more strongly in dim light, which might result in different clothing preferences in a cool environment from those associated with brighter light intensity. 相似文献
8.
It was investigated that active oxygen species (AOS) involved in the plant defense responses induced by fungal elicitor xylanase.
When xylanase from the fungusTrichoderma viridae was treated to tobacco suspension cultured cells as an elicitor, β-glucanase activity was increased markedly. Lignin biosynthesis
was also increased and peaked at 72 h after the treatment with xylanase. The treatment of H2O2 also dramatically increased β-glucanase activity at 24 h, which was much earlier than that of xylanase did. Using lucigenin-and
luminol-dependent chemiluminescence, the effects of xylanase on oxidative burst were examined. Superoxide anion (O2) production was peaked at 40 h and 52 h after xylanase treatment and hydrogen peroxide (H2O2) release was peaked at 44 h and 56 h, suggesting H2O2 burst was followed by O2 generation. The scavengers of AOS, n-propyl gallate (PG) and mannitol, inhibited xylanase-induced β-glucanase activity by
85% and 50%, respectively. The activity of superoxide dismutase (SOD), which catalyzes the dismutation of O2 to H2O2, began to increase from 24 h and reached to maximum at 48 h after xylanase treatment. Pretreatment of N,N,-diethyldithiocarbamate
(DDC), known as a SOD inhibitor, caused the inhibition of H2O2 generation by 80% and reduced the β-glucanase activity by 60%. Treatment of 2,5-norbonadiene (NBD), a specific ethylene-action
inhibitor, did not have any significant effect on xylanase-induced β-glucanase activity. This result suggested that ethylene
did not involve in xylanase-induced response. Our results strongly suggest that the AOS generation is an essential component
in plant defense response, in which cell wall degrading enzyme, glucanase, contributes to remove the necrotic tissue induced
by pathogens. 相似文献
9.
Homozygous mutations in fibroblast growth factor 3 are associated with a new form of syndromic deafness characterized by inner ear agenesis, microtia, and microdontia
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Tekin M Hişmi BO Fitoz S Ozdağ H Cengiz FB Sirmaci A Aslan I Inceoğlu B Yüksel-Konuk EB Yilmaz ST Yasun O Akar N 《American journal of human genetics》2007,80(2):338-344
We identified nine individuals from three unrelated Turkish families with a unique autosomal recessive syndrome characterized by type I microtia, microdontia, and profound congenital deafness associated with a complete absence of inner ear structures (Michel aplasia). We later demonstrated three different homozygous mutations (p.S156P, p.R104X, and p.V206SfsX117) in the fibroblast growth factor 3 (FGF3) gene in affected members of these families, cosegregating with the autosomal recessive transmission as a completely penetrant phenotype. These findings demonstrate the involvement of FGF3 mutations in a human malformation syndrome for the first time and contribute to our understanding of the role this gene plays in embryonic development. Of particular interest is that the development of the inner ear is completely disturbed at a very early stage--or the otic vesicle is not induced at all--in all of the affected individuals who carried two mutant FGF3 alleles. 相似文献
10.
Genovesio A Kwon YJ Windisch MP Kim NY Choi SY Kim HC Jung S Mammano F Perrin V Boese AS Casartelli N Schwartz O Nehrbass U Emans N 《Journal of biomolecular screening》2011,16(9):945-958
Recent genome-wide RNAi screens have identified >842 human genes that affect the human immunodeficiency virus (HIV) cycle. The list of genes implicated in infection differs between screens, and there is minimal overlap. A reason for this variance is the interdependence of HIV infection and host cell function, producing a multitude of indirect or pleiotropic cellular effects affecting the viral infection during RNAi screening. To overcome this, the authors devised a 15-dimensional phenotypic profile to define the viral infection block induced by CD4 silencing in HeLa cells. They demonstrate that this phenotypic profile excludes nonspecific, RNAi-based side effects and viral replication defects mediated by silencing of housekeeping genes. To achieve statistical robustness, the authors used automatically annotated RNAi arrays for seven independent genome-wide RNAi screens. This identified 56 host genes, which reliably reproduced CD4-like phenotypes upon HIV infection. The factors include 11 known HIV interactors and 45 factors previously not associated with HIV infection. As proof of concept, the authors confirmed that silencing of PAK1, Ku70, and RNAseH2A impaired HIV replication in Jurkat cells. In summary, multidimensional, visual profiling can identify genes required for HIV infection. 相似文献