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991.
992.
Allam KA Wan DC Kawamoto HK Bradley JP Sedano HO Saied S 《Plastic and reconstructive surgery》2011,127(2):812-821
Given the multiple permutations in craniofacial malformations, classification of median craniofacial dysplasia or midline Tessier no. 0 to 14 clefts has been difficult and disjointed. In this review, the authors present a summary of normal embryology, prior terminology, and their proposed new classification system. Median craniofacial dysplasia has tissue agenesis and holoprosencephaly at one end (the hypoplasias), frontonasal hyperplasia and excessive tissue (the hyperplasias) at the other end, and abnormal splitting or clefting and normal tissue volume (dysraphia) occupying the middle portion of the spectrum. These three distinct subclassifications have different forms of anomalies within their groups. 相似文献
993.
994.
? With growing concerns over serious ecological problems, a particular challenge is to reveal the complex mechanisms underlying rapid expansion of invasive species. Ageratina adenophora is of particular interest in addressing this question. ? We used geographic information systems and logistic regression to identify the geographic and environmental factors contributing to the presence of A. adenophora. Join-count spatial statistics with reproduction mode examination were employed to elucidate the spatiotemporal dispersal mechanisms. ? Multiple factors have significantly contributed to the rapid expansion of A. adenophora. Its biological traits, favoring dispersal by water and wind coupled with local spatiotemporally heterogeneous geography and ecology, promote invasion downstream and upstream along river valleys, while other factors associated with human activities facilitate its invasion over high mountains and across river valleys, providing new scope for progressive invasions. We further identified an unusual invasion event of A. adenophora subsequent to a great flood that amplified its dispersal ability from vegetative propagules and seeds. ? These findings suggest that dynamic interactions of multiple factors in heterogeneous ecogeographical environments - a 'combinatorial' invasion mechanism - would generate an unexpected invasion rate of an alien species or a seemingly stochastic invasion event. 相似文献
995.
The micronutrient content of most cereal grains is low and responsible for malnutrition deficiencies in millions of people who rely on grains as their primary food source. Any strategy that can increase the micronutrient content of grain will have significant benefits to world health. We identified a gene from barley encoding a cell wall protein with multiple histidine (His)-rich motifs interspersed with short arabinogalactan-protein (AGP) domains and have called it Hordeum vulgare His-rich AGP (HvHRA1). Sequence analysis shows that His-rich AGPs are rare in plants and that the number of His-rich and AGP domains differ between cereals and dicots. The barley and wheat encoded proteins have more than 13 His-rich domains, whereas the putative rice orthologue has only 5 His-rich regions. His-rich motifs are well-established metal-binding motifs; therefore, we developed transgenic (Tx) rice plants that constitutively overexpress barley HvHRA1. There was no significant effect on plant growth or grain yield in Tx plants. Purification of AGPs from wild-type and Tx plants showed that only Tx plants contained detectable levels of a His-rich AGP. Calcein assay shows that the AGP fraction from Tx plants had increased binding affinity for Cu(2+) . Micronutrient analysis of brown and white rice showed that the grain nutrient yield for Fe, Zn and Cu was higher in two Tx lines compared to their respective nulls, although the differences were not statistically significant. This approach highlights the potential of the plant apoplast (cell wall) for storage of key nutrients through overexpression of genes for metal-binding proteins. 相似文献
996.
Maks CJ Wan XS Ware JH Romero-Weaver AL Sanzari JK Wilson JM Rightnar S Wroe AJ Koss P Gridley DS Slater JM Kennedy AR 《Radiation research》2011,176(2):170-176
In the coming decades human space exploration is expected to move beyond low-Earth orbit. This transition involves increasing mission time and therefore an increased risk of radiation exposure from solar particle event (SPE) radiation. Acute radiation effects after exposure to SPE radiation are of prime importance due to potential mission-threatening consequences. The major objective of this study was to characterize the dose-response relationship for proton and γ radiation delivered at doses up to 2 Gy at high (0.5 Gy/min) and low (0.5 Gy/h) dose rates using white blood cell (WBC) counts as a biological end point. The results demonstrate a dose-dependent decrease in WBC counts in mice exposed to high- and low-dose-rate proton and γ radiation, suggesting that astronauts exposed to SPE-like radiation may experience a significant decrease in circulating leukocytes. 相似文献
997.
Objective
To investigate the mechanism for the dual effects of estrogen on vascular smooth muscle cells (VSMCs).Methods
Cultured rat VSMCs were exposed to gradient concentrations (10−9-10−5 M) of 17β-estradiol (E2) with or without pre-administration of a broad-spectrum CYP450 inhibitor 1-aminobenzotriazole (ABT) (10 × 10−6 M) and an estrogen receptor (ER) antagonist ICI 182,780 (10−6 M), respectively. The growth, cell cycle progression, premature senescence, estrogen metabolites, reactive oxygen species (ROS) and DNA damage of the cells were analyzed with cell counting assay, flow cytometry, Western blot, liquid chromatography-mass spectrometry and comet assay, respectively.Results
E2 in its physiological levels from 10−9 M to 10−8 M had a concentration-dependent promoting effect on growth of VSMCs. However, when the concentration increased over 10−8 M, the growth-promoting effect gradually reversed to a growth-inhibiting action. When the activity of CYP450s was blocked by ABT, the growth-promoting effect of E2 increased and did not reverse at high concentrations. Whereas when the ERs were blocked by ICI 182,780, E2 showed a pure growth-inhibiting effect. The E2 metabolites 2- and 4-hydroxyestradiols accumulated with the increase of E2 over 10−8 M, which accompanied by increased ROS, DNA damage and cellular senescence. All of these changes were eliminated by block of CYP450s, indicating that the VSMC growth inhibition by E2 is due to an increased production of ROS from accumulated E2 metabolites which induces DNA damage, leading to VSMC premature senescence.Conclusion
The complex effect of E2 is due to two opposite actions: one ER-mediated and proliferative, and the other estrogen metabolite-induced and pro-senescent. 相似文献998.
The synergism between the endo/exocellulase, Cel9A, and β-glucosidase (βgl) of Thermobifida
fusca was investigated. Wild type βgl or S319C, a βgl mutant with significantly improved cellobiase activity, were added to Cel9A.
Both wild type and mutant βgl enhanced the Cel9A hydrolysis of carboxymethyl cellulose (CMC) and filter paper by 50–100% compared
to Cel9A alone. No enhancement occurred with addition of E388A, an inactive form of βgl. HPLC analysis showed that, with Cel9A
alone, the resulting hydrolysate of glucose and cellobiose contained about half glucose; after addition of equimolar amounts
of either wild type βgl or mutant S319C to Cel9A, the hydrolysate contained more than 85% glucose. βgl thus acted synergistically
with Cel9A by converting cello-oligomers to glucose; this reduced the soluble sugar accumulation during hydrolysis of cellulose. 相似文献
999.
A novel 2,4-dichlorophenol hydroxylase (TfdB, EC 1.14.13.20) gene, designated as tfdB-JLU, was identified from a metagenome constructed from polychlorinated biphenyl-contaminated soil by functional screening and
heterologously expressed in Escherichia coli. The deduced amino acid sequence of tfdB-JLU exhibited less than 48% homology with other known TfdBs. The enzyme exhibited a wider substrate spectrum than the previously
reported TfdBs and higher relative activity towards ortho-substituted dichlorophenols, 2-chlorophenol, and 3-chlorophenol
than towards 2,4-dichlorophenol, the preferred substrate of other known TfdBs. The enzyme had a K
m
of 5 μM for 2,4-dichlorophenol and 6 μM for NADPH. The optimal temperature and pH of the enzyme were 25°C and 7.5, respectively.
Activity of the purified TfdB-JLU was slightly enhanced by Ca2+, Mn2+, Co2+, and Fe2+, and completely inhibited by Cu2+, Hg2+, and Zn2+. This study is the first report to identify a novel TfdB from a metagenome. 相似文献
1000.