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61.
Bo Li 《Journal of inorganic biochemistry》2010,104(7):718-14379
The complexation of uranium(VI) to variant functional groups of the highly phosphorylated protein phosvitin in aqueous solution was investigated by attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy. For the verification of the affinity of the actinyl ions to carboxyl and phosphate groups of the amino acid side chains, samples with different phosphate to uranium(VI) (P/U) ratios were investigated under denaturing conditions as well as in aqueous medium. From a comparative study with other heavy metal ions, i.e. Ba2+ and Pb2+, a strong coordination of U(VI) to carboxyl and phosphoryl groups can be derived. Furthermore, with increasing P/U ratios, a preferential binding of U(VI) to phosphoryl groups is indicated by the spectra of the batch samples. These findings are confirmed by spectra of aqueous U(VI)-phosvitin complexes reflecting an explicit coordination of the uranyl ions to phosphate groups at a high P/U ratio. Our study provides a deeper insight into the molecular interactions between actinyl ions and protein, and can be conferred to other basic biomolecules such as polysaccharides and nucleic acids. 相似文献
62.
The depth-related patterns in the benthic megafauna of the NE Weddell Sea shelf at the edge of the Fimbul Ice Shelf were investigated
at seven sites using towed camera platform photographs. Megafaunal density decreased with depth from 77,939 ha−1 at 245 m to 8,895 ha−1 at 510 m. While diversity was variable, with H′ ranging between 1.34 and 2.28, there were no depth related patterns. Multivariate analyses revealed two distinct assemblages;
a shallow assemblage with dense patches of suspension feeders in undisturbed areas and a deep assemblage where these were
not present. Disturbance from icebergs explained many observed patterns in faunal distribution. In shallow waters probable
effects of disturbance were observed as changes in successional stages; in deeper waters changes in habitat as a result of
past disturbance explained faunal distributions. In deeper areas ice ploughing created a mosaic landscape of fine and coarse
sediments. Total megafaunal density was highest in areas of coarse sediment (up to 2.9 higher than in finer sediment areas)
but diversity was highest in intermediate areas (H′ = 2.35). 相似文献
63.
自动感应照相系统在大熊猫以及同域分布的野生动物研究中的应用 总被引:5,自引:0,他引:5
鉴于野生大熊猫种群的濒危现状,已经不允许对其生境进行破坏性或干扰其行为活动较多的调查活动。例如,野生大熊猫个体数量稀少、其栖息地地形复杂或植被茂密,野外直接观察和调查野生大熊猫极为困难。自动感应照相系统是一种非损伤性野生动物调查工具,在很大程度上弥补了传统调查方法的不足,为野生动物的调查和研究提供了新的有效途径。本研究利用自行研究和开发的自动感应照相系统,获得了野生大熊猫及与其同域分布的其它物种的重要生态信息,显示了自动感应照相系统在物种鉴定、区系调查、个体识别、种群监测、性别确定和行为生态学研究等多方面的应用价值[动物学报51(3):495—500,2005]。 相似文献
64.
The use of camera traps in ecology helps affordably address questions about the distribution and density of cryptic and mobile species. The random encounter model (REM) is a camera‐trap method that has been developed to estimate population densities using unmarked individuals. However, few studies have evaluated its reliability in the field, especially considering that this method relies on parameters obtained from collared animals (i.e., average speed, in km/h), which can be difficult to acquire at low cost and effort. Our objectives were to (1) assess the reliability of this camera‐trap method and (2) evaluate the influence of parameters coming from different populations on density estimates. We estimated a reference density of black bears (Ursus americanus) in Forillon National Park (Québec, Canada) using a spatial capture–recapture estimator based on hair‐snag stations. We calculated average speed using telemetry data acquired from four different bear populations located outside our study area and estimated densities using the REM. The reference density, determined with a Bayesian spatial capture–recapture model, was 2.87 individuals/10km2 [95% CI: 2.41–3.45], which was slightly lower (although not significatively different) than the different densities estimated using REM (ranging from 4.06–5.38 bears/10km2 depending on the average speed value used). Average speed values obtained from different populations had minor impacts on REM estimates when the difference in average speed between populations was low. Bias in speed values for slow‐moving species had more influence on REM density estimates than for fast‐moving species. We pointed out that a potential overestimation of density occurs when average speed is underestimated, that is, using GPS telemetry locations with large fix‐rate intervals. Our study suggests that REM could be an affordable alternative to conventional spatial capture–recapture, but highlights the need for further research to control for potential bias associated with speed values determined using GPS telemetry data. 相似文献
65.
66.
Use of digital webcam images to track spring green-up in a deciduous broadleaf forest 总被引:6,自引:0,他引:6
Richardson AD Jenkins JP Braswell BH Hollinger DY Ollinger SV Smith ML 《Oecologia》2007,152(2):323-334
Understanding relationships between canopy structure and the seasonal dynamics of photosynthetic uptake of CO2 by forest canopies requires improved knowledge of canopy phenology at eddy covariance flux tower sites. We investigated whether
digital webcam images could be used to monitor the trajectory of spring green-up in a deciduous northern hardwood forest.
A standard, commercially available webcam was mounted at the top of the eddy covariance tower at the Bartlett AmeriFlux site.
Images were collected each day around midday. Red, green, and blue color channel brightness data for a 640 × 100-pixel region-of-interest
were extracted from each image. We evaluated the green-up signal extracted from webcam images against changes in the fraction
of incident photosynthetically active radiation that is absorbed by the canopy (f
APAR), a broadband normalized difference vegetation index (NDVI), and the light-saturated rate of canopy photosynthesis (A
max), inferred from eddy flux measurements. The relative brightness of the green channel (green %) was relatively stable through
the winter months. A steady rising trend in green % began around day 120 and continued through day 160, at which point a stable
plateau was reached. The relative brightness of the blue channel (blue %) also responded to spring green-up, although there
was more day-to-day variation in the signal because blue % was more sensitive to changes in the quality (spectral distribution)
of incident radiation. Seasonal changes in blue % were most similar to those in f
APAR and broadband NDVI, whereas changes in green % proceeded more slowly, and were drawn out over a longer period of time. Changes
in A
max lagged green-up by at least a week. We conclude that webcams offer an inexpensive means by which phenological changes in
the canopy state can be quantified. A network of cameras could offer a novel opportunity to implement a regional or national
phenology monitoring program. 相似文献
67.
BackgroundHypothermia is a problem for very premature infants after birth and leads to increased morbidity and mortality. Previously we found very premature infants exhibit abnormal thermal patterns, keeping foot temperatures warmer than abdominal temperatures for their first 12 h of life.PurposeWe explored the utility of infrared thermography as a non-invasive method for measuring body temperature in premature infants in an attempt to regionally examine differential temperatures.ResultsOur use of infrared imaging to measure abdominal and foot temperature for extremely premature infants in heated, humid incubators was successful and in close agreement using Bland and Altman technique with temperatures measured by skin thermistors.ConclusionsOur study methods demonstrated that it was feasible to capture full body temperatures of extremely premature infants while they were resting in a heated, humid incubator using a Flir SC640 infrared camera. This technology offers researchers and clinicians a method to examine acute changes in perfusion differentials in premature infants which may lead to morbidity. 相似文献
68.
Binder H 《European biophysics journal : EBJ》2007,36(4-5):265-279
The ordering and H-bonding characteristics of the hydration water of the lipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC)
were studied using polarized infrared spectroscopy by varying either the temperature or the relative humidity of the ambient
atmosphere of multibilayer samples. The OH-stretching band of lipid-bound water was interpreted by a simplified two-state
model of well-structured, low density “network” water and of less-structured dense “multimer” water. The IR-spectroscopic
data reflect a rather continuous change of the water properties with increasing distance from the membrane and with changing
temperature. Network and multimer water distribute across the whole polar interphase with changing composition and orientation.
Upon dehydration the fraction of network water increases from about 30 to 60%, a value which is similar to that in supercooled
water at −25°C. The highly ordered gel phase gives rise to an increased fraction of structured network water compared with
the liquid crystalline phase. The IR order parameter shows that the water dipoles rearrange from a more parallel towards a
more perpendicular orientation with respect to the membrane normal with progressive hydration.
Dedicated to Prof. K. Arnold on the occasion of his 65th birthday. 相似文献
69.
Hoa Tran Thanh Laurent Beney Thi Xuan Sam Nguyen Jean-Marc Belin 《生物化学与生物物理学报:生物膜》2007,1768(9):2256-2262
Linoleic acid hydroperoxide (HPOD), substrate of hydroperoxide lyase, an enzyme of the lipoxygenase pathway, can be transformed into many aromatic compounds, the so-called “green notes”. The presence of linoleic acid hydroperoxide in the culture medium of Yarrowia lipolytica, the yeast expressing the cloned hydroperoxide lyase of green bell pepper, undoubtedly exerted an inhibition on the growth and a toxic effect with 90% of yeast cells died after 120 min of exposition in 100 mM HPOD solution. The increase in cell membrane fluidity evaluated by measuring fluorescence generalized polarization with the increasing concentration of HPOD in the medium confirmed the fluidizing action of HPOD on yeast membrane. In addition, we determined by infrared spectroscopy measurement that this compound rapidly diffused into model phospholipids [1, 2-Dimyristoyl-D54-sn-Glycero-3-Phosphocholine (DMPC-D54)] bilayer, modifying their general physical state and their phase transition. In the presence of various concentrations of HPOD, the phase transition of DMPC-D54 occurred with an increase of both the corresponding wave number shift and the temperature range but the phase transition temperature was not modified. These results show that the toxic effects of HPOD on the yeast Yarrowia lipolytica may be initially linked to a strong interaction of this compound with the cell membrane phospholipids and components. 相似文献
70.
Lorin A Lins L Stroobant V Brasseur R Charloteaux B 《Biochemical and biophysical research communications》2007,355(3):649-653
In this study, we determined the minimal N-terminal fusion peptide of the gp30 of the bovine leukemia virus on the basis of the tilted peptide theory. We first used molecular modelling to predict that the gp30 minimal fusion peptide corresponds to the 15 first residues. Liposome lipid-mixing and leakage assays confirmed that the 15-residue long peptide induces fusion in vitro and that it is the shortest peptide inducing optimal fusion since longer peptides destabilize liposomes to the same extent but not shorter ones. The 15-residue long peptide can thus be considered as the minimal fusion peptide. The effect of mutations reported in the literature was also investigated. Interestingly, mutations related to glycoproteins unable to induce syncytia in cell-cell fusion assays correspond to peptides predicted as non-tilted. The relationship between obliquity and fusogenicity was also confirmed in vitro for one tilted and one non-tilted mutant peptide. 相似文献