bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spitzenkörper, Exocyst, and Polarisome Components in Candida albicans Hyphae Show Different Patterns of Localization and Have Distinct Dynamic Properties
Authors: Jones Laura A. , Sudbery Peter E. 
Published: August 2010

ABSTRACT

During the extreme polarized growth of fungal hyphae, secretory vesicles are thought to accumulate in a subapical region called the Spitzenkörper. The human fungal pathogen
Candida albicans
can grow in a budding yeast or hyphal form. When it grows as hyphae, Mlc1 accumulates in a subapical spot suggestive of a Spitzenkörper-like structure, while the polarisome components Spa2 and Bud6 localize to a surface crescent. Here we show that the vesicle-associated protein Sec4 also localizes to a spot, confirming that secretory vesicles accumulate in the putative
C. albicans
Spitzenkörper. In contrast, exocyst components localize to a surface crescent. Using a combination of fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) experiments and cytochalasin A to disrupt actin cables, we showed that Spitzenkörper-located proteins are highly dynamic. In contrast, exocyst and polarisome components are stably located at the cell surface. It is thought that in
Saccharomyces cerevisiae
exocyst components are transported to the cell surface on secretory vesicles along actin cables. If each vesicle carried its own complement of exocyst components, then it would be expected that exocyst components would be as dynamic as Sec4 and would have the same pattern of localization. This is not what we observe in
C. albicans
. We propose a model in which a stream of vesicles arrives at the tip and accumulates in the Spitzenkörper before onward delivery to the plasma membrane mediated by exocyst and polarisome components that are more stable residents of the cell surface.
TheCaulobacterTol-Pal Complex Is Essential for Outer Membrane Integrity and the Positioning of a Polar Localization Factor
Authors: Yeh Yi-Chun , Comolli Luis R. , Downing Kenneth H. , Shapiro Lucy , McAdams Harley H. 
Published: August 2010

ABSTRACTCell division inCaulobacter crescentusinvolves constriction and fission of the inner membrane (IM) followed about 20 min later by fission of the outer membrane (OM) and daughter cell separation. In contrast toEscherichia coli, theCaulobacterTol-Pal complex is essential. Cryo-electron microscopy images of theCaulobactercell envelope exhibited outer membrane disruption, and cells failed to complete cell division in TolA, TolB, or Pal mutant strains. In wild-type cells, components of the Tol-Pal complex localize to the division plane in early predivisional cells and remain predominantly at the new pole of swarmer and stalked progeny upon completion of division. The Tol-Pal complex is required to maintain the position of the transmembrane TipN polar marker, and indirectly the PleC histidine kinase, at the cell pole, but it is not required for the polar maintenance of other transmembrane and membrane-associated polar proteins tested. Coimmunoprecipitation experiments show that both TolA and Pal interact directly or indirectly with TipN. We propose that disruption of thetrans-envelope Tol-Pal complex releases TipN from its subcellular position. TheCaulobacterTol-Pal complex is thus a key component of cell envelope structure and function, mediating OM constriction at the final step of cell division as well as the positioning of a protein localization factor.
Regulation of Autotrophic CO
2
Fixation in the Archaeon
Thermoproteus neutrophilus
Authors: Ramos-Vera W. Hugo , Labonté Valérie , Weiss Michael , Pauly Julia , Fuchs Georg 
Published: August 2010

ABSTRACT

Thermoproteus neutrophilus
, a hyperthermophilic, chemolithoautotrophic, anaerobic crenarchaeon, uses a novel autotrophic CO
2
fixation pathway, the dicarboxylate/hydroxybutyrate cycle. The regulation of the central carbon metabolism was studied on the level of whole cells, enzyme activity, the proteome, transcription, and gene organization. The organism proved to be a facultative autotroph, which prefers organic acids as carbon sources that can easily feed into the metabolite pools of this cycle. Addition of the preferred carbon sources acetate, pyruvate, succinate, and 4-hydroxybutyrate to cultures resulted in stimulation of the growth rate and a diauxic growth response. The characteristic enzyme activities of the carbon fixation cycle, fumarate hydratase, fumarate reductase, succinyl coenzyme A (CoA) synthetase, and enzymes catalyzing the conversion of succinyl-CoA to crotonyl-CoA, were differentially downregulated in the presence of acetate and, to a lesser extent, in the presence of other organic substrates. This regulation pattern correlated well with the differential expression profile of the proteome as well as with the transcription of the encoding genes. The genes encoding phosphoenolpyruvate (PEP) carboxylase, fumarate reductase, and four enzymes catalyzing the conversion of succinyl-CoA to crotonyl-CoA are clustered. Two putative operons, one comprising succinyl-CoA reductase plus 4-hydroxybutyrate-CoA ligase genes and the other comprising 4-hydroxybutyryl-CoA dehydratase plus fumarate reductase genes, were divergently transcribed into leaderless mRNAs. The promoter regions were characterized and used for isolating DNA binding proteins. Besides an Alba protein, a 18-kDa protein characteristic for autotrophic
Thermoproteales
that bound specifically to the promoter region was identified. This system may be suitable for molecular analysis of the transcriptional regulation of autotrophy-related genes.
Genetic Analysis of the Nitrogen Assimilation Control Protein from
Klebsiella pneumoniae
Authors: Rosario Christopher J. , Janes Brian K. , Bender Robert A. 
Published: August 2010

ABSTRACT

The nitrogen assimilation control protein (NAC) from
Klebsiella pneumoniae
is a typical LysR-type transcriptional regulator (LTTR) in many ways. However, the lack of a physiologically relevant coeffector for NAC and the fact that NAC can carry out many of its functions as a dimer make NAC unusual among the LTTRs. In the absence of a crystal structure for NAC, we analyzed the effects of amino acid substitutions with a variety of phenotypes in an attempt to identify functionally important features of NAC. A substitution that changed the glutamine at amino acid 29 to alanine (Q29A) resulted in a NAC that was seriously defective in binding to DNA. The H26D substitution resulted in a NAC that could bind and repress transcription but not activate transcription. The I71A substitution resulted in a NAC polypeptide that remained monomeric. NAC tetramers can bind to both long and shorter binding sites (like other LTTRs). However, the absence of a coeffector to induce the conformational change needed for the switch from the former to the latter raised a question. Are there two conformations of NAC, analogous to the other LTTRs? The G217R substitution resulted in a NAC that could bind to the longer sites but had difficulty in binding to the shorter sites, and the I222R and A230R substitutions resulted in a NAC that could bind to the shorter sites but had difficulty in binding properly to the longer sites. Thus, there appear to be two conformations of NAC that can freely interconvert in the absence of a coeffector.
WAVE SOLUTIONS OF THE VORTICITY EQUATION FOR THE 2½-DIMENSIONAL MODEL
Authors: Ogura Y. 
Published: August 2010

Abstract
Wave solutions of the non-linear quasi-geostrophic equations for the so-called “2½-dimensional model” without friction are derived. The solutions describe wave motions which propagate at different speeds in each layer. The amplitudes of the disturbances, are either changing periodically with time (stable waves) or increasing exponentially (unstable waves). The critical value of wavelength, at which waves maintain a constant amplitude, is expressed as a function of thermal stability and of vertical wind shear in the basic current.
It is also found that, while the inclination of trough lines to the vertical increases monotonically with time in stable waves, it varies very slowly in the unstable waves and tends to approach a certain limiting value.
A GENERALIZATION OF AVERAGE-CORRELATION METHODS OF SPECTRUM ANALYSIS
Authors: Kahn Arthur B. 
Published: August 2010

Abstract
The power spectrum of truncated variables is developed as the transform of the correlation function of data smoothed by an arbitrary mean, as a function of both lag and averaging intervals. It is shown that a large class of techniques for computing spectra can be readily derived as special cases of this more general approach. These include the conventional approach of Taylor as well as various methods in current use.
The need for further study of the numerical effects of the approximations used in applying these techniques to finite records of discrete data is indicated.
Comparison of Simultaneous Airborne and Radiometric Measurements of Supercooled Liquid Water
Authors: Hill Geoffrey E. 
Published: August 2010

AbstractSimultaneous measurements of supercooled liquid water by an instrumented aircraft and a dual-frequency microwave radiometer were made at Lake Ontario, New York, during wintertime. The geographic location and typical meteorological conditions for making the measurements were specifically selected to facilitate the comparisons. Flight paths from below cloud base to above cloud tops were made over the radiometer site. Seven flights were made; supercooled liquid water was measured by a calibrated Rosemount icing meter.The primary finding is that when the temperature of the atmosphere in the viewing path of the radiometer is below the melting point of ice, the airborne liquid-water measurements are in general agreement with the radiometric measurements. When an inversion with the temperature above the melting point is present, the radiometric readings of liquid water are much larger than the values found from the aircraft. Also, the, possibility is raised that in very heavy snowfall with large ice particles the amount of supercooled liquid water will appear too large according to the radiometer.
Effect of Topology of Water-Ice Mixture on Radar Backscattering by Hailstones
Authors: Chýlek Peter , Pinnick R. G. , Srivastava V. 
Published: August 2010

AbstractThe radar backscattering cross sections of spongy hailstones are considerably influenced by the topological structure of the water-ice mixture. Observational evidence suggests that such an inhomogeneous composite medium can consist of regions of different topologies. We investigate three different kinds of topologies and derive a general mixed topology mixing rule (MTMR). The mixed topology rule is used to calculate the effective dielectric constant of spongy ice as a function of its liquid-water content. This leads to predictions of backscatter cross sections that are in good agreement with measurement.
Improved Accuracy of Radar WPMM Estimated Rainfall upon Application of Objective Classification Criteria
Authors: Rosenfeld Daniel , Amitai Eyal , Wolff David B. 
Published: August 2010

Abstract
Application of the window probability matching method to radar and rain gauge data that have been objectivelyclassified into different rain types resulted in distinctly different Ze-R relationships for the various classifications.The classification parameters, in addition to the range from the radar, are (a) the horizontal radial reflectivitygradients [dB km-1; (b) the cloud depth, as scaled by the effective efficiency; (c) the brightband fraction withinthe radar field window; and (d) the height of the freezing level. Combining physical parameters to identify thetype of precipitation and statistical relations most appropriate to the precipitation types results in considerableimprovement of both point and areal rainfall measurements. A limiting factor in the assessment ofthe improvedaccuracy is the inherent variance between the true rain intensity at the radar measured volume and the rainintensity at the mouth of the rain gauge. Therefore, a very dense rain gauge network is required to validate mostof the suggested realized improvement.
A rather small sample size is required to achieve a stable Ze-R relationship (standard deviation of 15% of Rfor a given Ze)-about 200 mm of rainfall accumulated in all gauges combined for each classification.
Recursive Filter Objective Analysis of Meteorological Fields: Applications to NESDIS Operational Processing
Authors: Hayden Christopher M. , Purser R. James 
Published: August 2010

Abstract
A recursive filter objective analysis method is described. It is a "successive approximation" system with the particular feature of locally varying scaling, making it especially appropriate for dealing with inhomogeneous data. Attention is given to proper treatment of lateral boundaries, which permit its use in limited domains. Thissystem provides estimates of input data quality that can be used for editing datasets before their distribution and for the weighting of data in application by other users, Two- and three-dimensional versions of the analysis operating on a Cartesian grid are used operationally at the National Environmental Satellite and Data InformationService. They are used both in the production of data and for quality control prior to dissemination. Examplesof these applications are given.
Aircraft Icing Measurements in East Coast Winter Storms
Authors: Cober Stewart G. , Isaac George A. , Strapp J. W. 
Published: August 2010

AbstractAnalysis of the aircraft icing environments of East Coast winter storms have been made from 3 1 flights duringthe second Canadian Atlantic Storms Program. Microphysical parameters have been summarized and are compared to common icing intensity envelopes and to other icing datasets. Cloud regions with supercooled liquid water had an average horizontal extent of 4.3 km, with average droplet concentrations of 130 μ, liquid water contents of 0.13 g m-3, and droplet median volume diameters of 18 pm. In general, the icing intensity observed was classified as light, although moderate to severe icing was observed in several common synoptic situationsand several cases are discussed. Freezing drizzle was observed on four flights, and represented the most severeicing environment encountered.
The Retrieval of Marine Stratiform Cloud Properties from Multiple Observations in the 3.9-µm Window under Conditions of Varying Solar Illumination
Authors: Kleespies Thomas J. 
Published: August 2010

Abstract
Radiometric observations in the 3.9-µm region have been used by a number of investigators for the determination of cloud parameters or sea surface temperature at night. Only a few attempts have been made to perform quantitative assessments of cloud and surface properties during the daytime because of the inability to distinguish between the thermal and solar components of the satellite-sensed radiances. This paper presents a new method of separating the thermal and solar components of upwelling 3.9-µm radiances.
Two collocated satellite observations are made under conditions where the solar illumination angle changes but the thermal structure of the cloud and atmosphere, as well as the cloud microphysics change very little. These conditions can easily be met by observing the same cloud from geosynchoronous orbit over a short time interval during the morning hours. When the radiances are differenced under these constraints, the thermal components cancel, and the difference in the radiances is simply the difference in the solar component. With a few simplifying assumptions, a cloud microphysical property, specifically effective radius, can be inferred. This parameter is of particular importance to both climate modeling and global change studies. The methodology developed in this paper is applied to data from the Visible-Infrared Spin Scan Radiometer Atmospheric Sounder onboard the GOES-7 spacecraft for a period in August 1992.
Assimilation of SSM/I and GOES Humidity Retrievals with a One-Dimensional Variational Analysis Scheme
Authors: Deblonde Godelieve , Garand Louis , Gauthier Pierre , Grassotti Christopher 
Published: August 2010

Abstract
Total precipitable water (TPW) retrieved from Special Sensor Microwave/lmager (SSM/I) brightness temperatures and specific humidity retrieved from Geostationary Operational Environmental Satellite (GOES) radiances are assimilated using a one-dimensional (ID) variational analysis technique. The study is divided into two parts. First, collocations with radiosondes are performed to arm the quality of the satellite water vapor retrievals. Collocations are also performed with 6-h forecast Acids. Second, SSM/I TPW and GOES specific humidity are assimilated using a ID variational analysis technique that minimizes the error variance of the analyzed field.
A global collocation study over the oceans for SSM/I TPW retrievals and 6-h forecasts of TPW shows that the rmse (with respect to radiosondes) are, respectively, 4.7 and 5.0 kg m−2. A separate collocation study over both the oceans and land for GOES retrieved TPW and 6-h forecasts of TPW yields rmse of 4.6 and 4.4 kg m−2, respectively, in the midlatitudes and 6.8 and 5.9 kg m−2 in the Tropics.
The reduction of the 6-h forecast rmse when assimilating SSM/I TPW is 1 kg m−2, which is a reduction of 20% in the rmse. When GOES retrievals of specific humidity are assimilated, the elective reduction is 0.6 kg m−2. It is shown that in the upper levels of the troposphere (above 600 mb), the error reduction of specific humidity is largely due to the GOES retrievals, whereas in the lower troposphere (850 and 700 mb), the reduction is mostly due to the SSM/I TPW. This emphasizes the complementarity of the information contained at different wavelengths and the advantage of using multisensor retrievals in data analysis.
A Water Vapor Index from Satellite Measurements
Authors: McMillin Larry M. , Crosby David S. , Goldberg Mitchell D. 
Published: August 2010

Abstract
A method for deriving a water vapor index is presented. An important feature of the index is the fact that it does not rely on radiosondes. Thus, it is not influenced by problems associated with radiosondes and the extent to which the horizontal variability of moisture invalidates the extrapolations from radiosonde measurements to satellite measurements. The index is derived by using channels that are insensitive to changes in moisture to predict a brightness temperature for one of the moisture channels and then by subtracting this predicted value from the observation. The predicted value represents the moisture value expected for the given temperature profile, and the difference between the predicted and measured values is the index. The subtraction removes the variability due to changes in atmospheric temperature from the moisture signal. This separation greatly enhances the ability to monitor atmospheric moisture patterns, especially near the ground and at high latitudes where some alternative methods have difficulties. The ability of the indices to display moisture patterns at all levels and latitudes is demonstrated.
The Role of Visible Data in Improving Satellite Rain-Rate Estimates
Authors: King Patrick W. S. , Hogg William D. , Arkin Philip A. 
Published: August 2010

Abstract
Data from the first Algorithm Intercomparison Project(AIP/1) collected over Japan and surrounding waters in June, July, and August 1989 are used in this study to assess the importance of visible data in satellite rain estimation techniques. The purpose of the project was to compare different methods for estimating rainfall using satellite measurements. Radar and surface gauge data provided the validation set.
RAINSAT, an estimation technique using both visible (VIS) and infrared (IR) data, achieved the highest correlation with the validation data. In this paper rainfall estimates from RAINSAT (VIS+IR) am compared with two IR-only techniques to deduce the effectiveness of VIS data. Some estimates are also made using a VIS-only technique. Comparisons am made on both a spatial and diurnal basis.
Cloud climatologies for a subset of the AIP/1 data and the southern Ontario data on which RAINSAT was trained showed a marked similarity. It is found that the total volume of rain as a function of albedo is very similar for both Japanese and Ontario data.
The VIS data generally produced higher correlations with the validation data than did the IR data. This was especially the case when rain fell from warm, orogaphically induced rainfall. When rain fell from cold bright clouds. especially over the ocean, the correlations of the two types of data with the validation data were similar.
It is also shown that normalization of VIS data by the cosine of solar zenith data was inadequate to remove diurnal variations in apparent brightness.
Growth and Decay of Error in a Numerical Cloud Model Due to Small Initial Perturbations and Parameter Changes
Authors: Li Qihang , Bras Rafael L. , Islam Shafiqul 
Published: August 2010

Abstract
The behavior of a numerical cloud model is investigated in terms of its sensitivity to perturbations with two kinds of lateral boundary conditions: 1) with cyclic lateral boundary conditions, the model is sensitive to many aspects of its structure, including a very small potential temperature perturbation at only one grid point, changes in time step, and small changes in parameters such as the autoconversion rate from cloud water to rainwater and the latent heat of vaporization; 2) with prescribed lateral boundary conditions, growth and decay of perturbations are highly dependent on the flow conditions inside the domain. It is shown that under relatively uniform (unidirectional) advection across the domain, the perturbations will decay. On the other hand, convergence, divergence, or, in general, flow patterns with changing directions support error growth. This study shows that it is the flow structure inside the model domain that is important in determining whether the prescribed lateral boundary conditions will result in decaying or growing perturbations. The numerical model is inherently sensitive to initial perturbations, but errors can decay due to advection of information from lateral boundaries across the domain by uniform flow. This result provides one explanation to the reported results in earlier studies showing both error growth and decay.