bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships between polar mesospheric clouds, temperature, and water vapor from Solar Occultation for Ice Experiment (SOFIE) observations
Authors: Hervig Mark E. , Stevens Michael H. , Gordley Larry L. , Deaver Lance E. , Russell James M. , Bailey Scott M.
Published: October 2009

The goal of this work is to explore relationships between polar mesospheric clouds (PMCs), temperature, and water vapor and to understand the extent that bulk thermodynamic equilibrium can explain observed PMC characteristics. We use observations from the Solar Occultation for Ice Experiment (SOFIE) and employ a simple PMC model which assumes that ice exists in thermodynamic equilibrium with the local temperature and water vapor. Model results using SOFIE temperatures and water vapor are found to reproduce the observed ice layer altitudes, ice frequency versus time and altitude, ice mass density (expressed as the gas phase equivalent contained in the ice phase, Qice) versus time and altitude, and the vertical column abundance of ice (or ice water content (IWC)). The differences (model ‐ SOFIE) for July 2008 were −0.1 km in the altitude of peak ice mass density (Zmax), 16% in Qice at Zmax, and 35% in IWC. These results suggest that on average, PMCs can exist in equilibrium with the surrounding environment, and the results also imply that ice nucleation may occur throughout the PMC altitude range. Good correlations were found between ice abundance and temperature (or saturation ratio), although knowledge of both water vapor and temperature is required for a quantitative prediction of observed ice characteristics. Our results indicate that the seasonal dependence of ice abundance is generally controlled by temperature and that in a broad sense, changes in water vapor are a result of changes in ice. We also find that lower temperatures are associated with higher ice mass density, higher ice concentration, and slightly smaller particle radii. This finding indicates that the increase in ice mass density is due to the nucleation of more particles rather than the growth of existing ice, and this finding points to nucleation as an important factor in determining PMC variability.
AIRS‐based versus flask‐based estimation of carbon surface fluxes
Authors: Chevallier Frédéric , Engelen Richard J. , Carouge Claire , Conway Thomas J. , Peylin Philippe , Pickett‐Heaps Christopher , Ramonet Michel , Rayner Peter J. , Xueref‐Remy Irène
Published: October 2009

This paper demonstrates an inversion of surface CO2 fluxes using concentrations derived from assimilation of satellite radiances. Radiances come from the Atmospheric Infrared Sounder (AIRS) and are assimilated within the system of the European Centre for Medium‐Range Weather Forecasts. We evaluate the quality of the inverted fluxes by comparing simulated concentrations with independent airborne measurements. As a benchmark we use an inversion based on surface flask measurements and another using only the global concentration trend. We show that the AIRS‐based inversion is able to improve the match to the independent data compared to the prior estimate but that it usually performs worse than either the flask‐based or trend‐based inversion.
Edge states and possible magnetic states in nanographene and open-shell conjugated systems
Authors: Harigaya Kikuo
Published: October 2009

Nanocarbon materials are investigated intensively. In this paper, the edge-state in nanographene materials with zigzag edges is studied theoretically. In particular, while the inter-layer interactions are considered, we prove that edge states exist at the energy of the Dirac point in the doubly stacked nanographene, and in the case of the infinitely-wide lower layer case. This property applies both for the A-B and A-C stackings. We also study possible magnetic properties in fullerenes with defects and buckybowl molecules. When the number of lattice defects in C60 is even, we obtain magnetic and nonmagnetic solutions. The total energy of the nonmagnetic solution is lower than that of the magnetic solution. The occurrence of the localized spin is reduced for finite onsite Coulomb repulsions. When the number of defects is odd, magnetic solutions are obtained only. The spin density reflects the symmetry of the molecules. We also consider possible magnetic states in buckybowl molecules. We find localized spin order in the sumanene molecule and a part of the C60.
Hypolipidemic Effect of Fenugreek Seeds Is Mediated Through Inhibition of Fat Accumulation and Upregulation of LDL Receptor
Authors: Vijayakumar Maleppillil V. , Pandey Vimal , Mishra Gyan C. , Bhat Manoj K.
Published: October 2009

Fenugreek (Trigonella foenum‐graecum) seeds, used as a condiment, are documented for health benefits including amelioration of abnormalities in lipid homeostasis due to its hypolipidemic properties. However, molecular mechanisms underlying the hypolipidemic effect of fenugreek seeds remain obscure. In this study, hypolipidemic effect of a novel thermostable extract of fenugreek seeds (TEFS) was evaluated in vitro by employing differentiating and differentiated 3T3‐L1 cells, and HepG2 cells cultured in normal or sterol‐enriched conditions. Hypolipidemic effect was studied by quantifying decrease in accumulation of fat or by western blot analysis of adipogenic and lipogenic factors. At molecular level, TEFS inhibited accumulation of fat in differentiating and differentiated 3T3‐L1 cells via decreased expression of adipogenic factors such as peroxisome proliferators activated‐receptor‐γ (PPAR‐γ), sterol regulatory element‐binding protein‐1 (SREBP‐1), and CAAT element‐binding proteins‐α (c/EBP‐α). We also show that following TEFS treatment, cellular triglycerides (TGs), and cholesterol concentrations decreased significantly (P < 0.05) in HepG2 cells via reduced expression of SREBP‐1, at mRNA as well as protein level. Under sterol enriched condition, TEFS upregulated low‐density lipoprotein receptor (LDLR) expression resulting in enhanced LDL uptake. Treating fat supplement fed C57BL6/J mice with TEFS for 15 days resulted in decrease of serum TG, LDL‐cholesterol (LDLc), and body weight in a dose‐ and time‐dependent manner (P < 0.05). Results indicate that hypolipidemic effect of TEFS is due to inhibition of fat accumulation and upregulation of LDLR. Taken together, the study suggests that TEFS may have potential application in the management of dyslipidemia and its associated metabolic disorders.
Hypothalamic Paraventricular Nucleus Lesion Involvement in the Sympathetic Control of Lipid Mobilization
Authors: Foster Michelle T. , Song C. Kay , Bartness Timothy J.
Published: October 2009

The sympathetic nervous system (SNS) innervation of white adipose tissue (WAT) is the principal initiator of lipolysis. Using pseudorabies virus, a transneuronal viral tract tracer, brain sites involved in the SNS outflow to WAT have been identified previously by us. One of these sites, the hypothalamic paraventricular nucleus (PVH) that shows predominantly unilateral sympathetic outflow from each half of the nucleus to ipsilaterally located WAT depots, was tested for laterality in lipid accumulation/mobilization in Siberian hamsters. First we tested whether unilateral PVH electrolytic lesions (PVHx) would increase lipid accumulation in WAT pads ipsilateral to the side of the PVHx. PVHx significantly increased body and WAT pad masses compared with sham PVHx; however, there was no laterality effect. In addition, bilateral PVHx increased body and WAT pad masses, as well as food intake, to a greater extent than did unilateral PVHx. We next tested for possible laterality effects on WAT lipid mobilization using food deprivation as the lipolytic stimulus in hamsters bearing unilateral or bilateral PVHx. Lipid mobilization was not prevented, as indicated indirectly by WAT mass and thus laterality of lipid mobilization could not be tested. We then tested whether removal of adrenal catecholamines via adrenal demedullation (ADMEDx) alone, or combined with bilateral PVHx, would block food deprivation–induced lipid mobilization, but neither did so. These results suggest that an intact PVH is not necessary for food deprivation–induced lipid mobilization and support the primacy of the SNS innervation of WAT, rather than adrenal medullary catecholamines, for lipid mobilization from WAT.
Prenatal Exposure to Maternal Cigarette Smoking and Accumulation of Intra‐abdominal Fat During Adolescence
Authors: Syme Catriona , Abrahamowicz Michal , Mahboubi Amel , Leonard Gabriel T. , Perron Michel , Richer Louis , Veillette Suzanne , Gaudet Daniel , Paus Tomas , Pausova Zdenka
Published: October 2009

In industrialized countries, prenatal exposure to maternal cigarette smoking (PEMCS) is the most common environmental insult to the fetus. Here, we tested the hypothesis that PEMCS amplifies accumulation of abdominal fat during the accelerated weight gain occurring in late puberty. This hypothesis was tested in 508 adolescents (12–18 years, 237 exposed prenatally to maternal cigarette smoking) in whom subcutaneous and intra‐abdominal fat were quantified with magnetic resonance imaging (MRI). We found that, in early puberty, exposed and nonexposed adolescents did not differ in MRI‐based measures of adiposity. In late puberty, on the other hand, exposed compared with nonexposed adolescents demonstrated markedly higher quantities of both subcutaneous fat (by 26%,P= 0.004) and intra‐abdominal fat (by 33%,P= 0.001). These group differences remained virtually unchanged after adjusting for sex and potential confounders, including birth weight and breastfeeding. As such, our results suggest that PEMCS may represent a major risk factor for the development of abdominal obesity at the later stages of puberty.
The Desire to Eat in the Presence of Obese or Normal‐weight Eaters as a Function of Their Emotional Facial Expression
Authors: Barthomeuf Laétitia , Rousset Sylvie , Droit‐Volet Sylvie
Published: October 2009

The aim of this study was to investigate whether the eating desire would be lower in the presence of facial expression of an obese than of a normal‐weight eater in participants who were or not themselves obese. Normal‐weight and obese participants assessed their desire to eat liked and disliked foods. These foods were presented alone and with a normal‐weight and obese eater expressing pleasure, disgust, or neutrality. Results showed that, compared with a normal‐weight eater, perceiving an obese eater decreased the viewer's desire to eat, whatever his/her facial expression. Thus, pleasant faces of normal weight but not of obese eaters increased the eating desire. Furthermore, the influence of eater's facial expressions did not differ as a function of the participants' BMIs. These data were discussed in the framework of the embodiment theory of emotion and of their implications in terms of nutritional education, either by enabling people to learn to like certain unpalatable foods or by helping them moderate their food intake simply through the sight of an obese eater.
Regulatory SNP in the RBP4 Gene Modified the Expression in Adipocytes and Associated With BMI
Authors: Munkhtulga Lkhagvasuren , Nagashima Shuichi , Nakayama Kazuhiro , Utsumi Nanami , Yanagisawa Yoshiko , Gotoh Takaya , Omi Toshinori , Kumada Maki , Zolzaya Khadbaatar , Lkhagvasuren Tserenkhuu , Kagawa Yasuo , Fujiwara Hiroyuki , Hosoya Yoshinori , Hyodo Masanobu , Horie Hisanaga , Kojima Masayuki , Ishibashi Shun , Iwamoto Sadahiko
Published: October 2009

Retinol‐binding protein 4 (RBP4) is a recently identified adipokine that was involved in insulin resistance. RBP4 is predominantly expressed from the liver in normal metabolic state to transport retinoids throughout the body, but the exact physiological function and the regulatory mechanisms of adipocyte‐derived RBP4 have not been revealed. We conducted the genetic analysis about metabolic parameters in Japanese and Mongolian; the minor allele carriers of regulatory single‐nucleotide polymorphism (SNP −803G>A) showed significantly higher BMI in Japanese men (P = 0.009) and women (P = 0.017), and in Mongolian women (P = 0.009). Relative quantification of RBP4 transcripts in −803GA heterozygotes showed that the minor allele–linked haplotype‐derived mRNA was significantly more abundant than the transcript from major allele. RBP4 promoter assay in 3T3L1 adipocytes revealed that the minor allele increased the promoter activity double to triple and the administration of 9‐cis‐retinoic acid (RA) and 8‐bromo‐cyclic adenosine monophosphate (8‐Br‐cAMP) enhanced the activity. Multiple alignment analysis of human, mouse, rat, and cattle RBP4 promoter suggested conserved seven transcription factor binding motifs. Electrophoretic mobility shift assay showed the −803G>A SNP modulate the affinity against unidentified DNA‐binding factor, which was assumed to be a suppressive factor. These results collectively suggested that the minor allele of RBP4 regulatory SNP enhanced the expression in adipocytes, which may be associated with the adipogenesis.
Identifying Metabolically Healthy but Obese Individuals in Sedentary Postmenopausal Women
Authors: Messier Virginie , Karelis Antony D. , Prud'homme Denis , Primeau Vanessa , Brochu Martin , Rabasa‐Lhoret Rémi
Published: October 2009

The purpose of this study was to compare different methods to identify metabolically healthy but obese (MHO) individuals in a cohort of obese postmenopausal women. We examined the anthropometric and metabolic characteristics of 113 obese (age: 57.3 ± 4.8 years; BMI: 34.2 ± 2.7 kg/m2), sedentary postmenopausal women. The following methods were used to identify MHO subjects: the hyperinsulinemic–euglycemic clamp (MHO: upper quartile of glucose disposal rates); the Matsuda index (MHO: upper quartile of the Matsuda index); the homeostasis model assessment (HOMA) index (MHO: lower quartile of the HOMA index); having 0–1 cardiometabolic abnormalities (systolic/diastolic blood pressure ≥130/85 mm Hg, triglycerides (TG) ≥1.7 mmol/l, glucose ≥5.6 mmol/l, HOMA >5.13, high‐sensitive C‐reactive protein (hsCRP) >0.1 mg/l, high‐density lipoprotein‐cholesterol (HDL‐C) <1.3 mmol/l); and meeting four out of five metabolic factors (HOMA ≤2.7, TG ≤1.7 mmol/l, HDL‐C ≥1.3 mmol/l, low‐density lipoprotein‐cholesterol ≤2.6 mmol/l, hsCRP ≤3.0 mg/l). Thereafter, we measured insulin sensitivity, body composition (dual‐energy X‐ray absorptiometry), body fat distribution (computed tomography scan), energy expenditure, plasma lipids, inflammation markers, resting blood pressure, and cardiorespiratory fitness. We found significant differences in body composition (i.e., peripheral fat mass, central lean body mass (LBM)) and metabolic risk factors (i.e., HDL‐C, hsCRP) between MHO and at risk individuals using the different methods to identify both groups. In addition, significant differences between MHO subjects using the different methods to identify MHO individuals were observed such as age, TG/HDL, hsCRP, and fasting insulin. However, independently of the methods used, we noted some recurrent characteristics that identify MHO subjects such as TG, apolipoprotein B, and ferritin. In conclusion, the present study shows variations in body composition and metabolic profile based on the methods studied to define the MHO phenotype. Therefore, an expert consensus may be needed to standardize the identification of MHO individuals.
Weight Status Continuity and Change From Adolescence to Young Adulthood: Examining Disease and Health Risk Conditions
Authors: Merten Michael J.
Published: October 2009

This study examined weight status during adolescence and young adulthood, and young adult health condition diagnosis. Data are from 10,439 African‐American, Hispanic, and white men and women participating in the National Longitudinal Study of Adolescent Health during Waves 1 (adolescence: ages 12–19) and 3 (young adulthood: ages 19–26). Categories were created differentiating individuals based on their weight status during adolescence and young adulthood: (i) obese during adolescence and young adulthood (i.e., continuously obese), (ii) obese during adolescence only, (iii) obese during young adulthood only, and (iv) never obese. Multilevel random intercept regression models were used to examine the impact of obesity category, sex, and race/ethnicity on young adult asthma, diabetes, high cholesterol, and high blood pressure. Continuous obesity increased the likelihood for young adult disease and health risk conditions compared to individuals who were never obese. Obesity isolated to adolescence (Wave 1) increased the likelihood for high cholesterol and high blood pressure, whereas obesity isolated to young adulthood (Wave 3) also increased the likelihood for diabetes—all increases were relative to nonobese weight status during both periods. Associations varied in direction and degree when sex and race/ethnicity were considered. Findings clarify some of the mixed understandings regarding the associations between age of onset and stability of obesity, and health outcomes with important public health implications. Although results indicate obesity isolated to a single developmental period does have health repercussions, obesity experienced continuously during adolescence and young adulthood greatly intensified risk across all health conditions.
Targeting of inositol 1,4,5-trisphosphate receptor to the endoplasmic reticulum by its first transmembrane domain
Authors: Pantazaka Evangelia , Taylor Colin W.
Published: October 2009

Targeting of IP3R (inositol 1,4,5-trisphosphate receptors) to membranes of the ER (endoplasmic reticulum) and their retention within ER or trafficking to other membranes underlies their ability to generate spatially organized Ca2+ signals. N-terminal fragments of IP3R1 (type 1 IP3R) were tagged with enhanced green fluorescent protein, expressed in COS-7 cells and their distribution was determined by confocal microscopy and subcellular fractionation. Localization of IP3R1 in the ER requires translation of between 26 and 34 residues beyond the end of the first transmembrane domain (TMD1), a region that includes TMD2 (second transmembrane domain). Replacement of these post-TMD1 residues with unrelated sequences of similar length (24–36 residues) partially mimicked the native residues. We conclude that for IP3R approx. 30 residues after TMD1 must be translated to allow a signal sequence within TMD1 to be extruded from the ribosome and mediate co-translational targeting to the ER. Hydrophobic residues within TMD1 and TMD2 then ensure stable association with the ER membrane.
Reversible bleb formation in mast cells stimulated with antigen is Ca2+/calmodulin-dependent and bleb size is regulated by ARF6
Authors: Yanase Yuhki , Carvou Nicolas , Frohman Michael A. , Cockcroft Shamshad
Published: October 2009

Mast cells stimulated with antigen undergo extensive changes in their cytoskeleton. In the present study, we assess the impact of actin-modifying drugs and report that, in the presence of cytochalasin D, mast cells stop membrane ruffling, but instead bleb. Bleb formation is reversible following washout of cytochalasin D and occurs in an actin-polymerization-dependent manner. Bleb formation is inhibited by expression of constitutively active ezrin-T567D. Blebbing is also inhibited by blebbistatin, a myosin II inhibitor, implying myosin II activation in the process. We used a selection of inhibitors and observed that myosin II activation is dependent mainly on Ca2+–calmodulin, with only a small contribution from Rho kinase. The signalling pathways stimulated by antigen include PLC (phospholipase C) and PLD (phospholipase D). Bleb formation was dependent on activation of PLC, but not PLD. Primary alcohols, used previously as a means to reduce PLD-derived phosphatidic acid, were potent inhibitors of membrane blebbing, but a more selective inhibitor of PLD, FIPI (5-fluoro-2-indolyl des-chlorohalopemide), was without effect. FIPI also did not inhibit membrane ruffling or degranulation of mast cells, indicating that inhibition by primary alcohols works through an unidentified mechanism rather than via diversion of PLD activity as assumed. We also examined the requirement for ARF6 (ADP-ribosylation factor 6) and observed that its expression led to an increase in bleb size and a further increase was observed with the dominant-active mutant, ARF6-Q67L. Since ARF6-T27N had no effect on bleb size, we conclude that ARF6 needs to be active to regulate the size of the blebs.
Carbon monoxide emissions by phytoplankton: evidence from laboratory experiments
Authors: Gros Valérie , Peeken Ilka , Bluhm Katrin , Zöllner Eckart , Sarda-Esteve Roland , Bonsang Bernard
Published: October 2009

Environmental context. Carbon monoxide (CO) is a key component for atmospheric chemistry and its production in the ocean, although minor at the global scale, could play a significant role in the remote marine atmosphere. Up to now, CO production in the ocean was considered to mainly originate from the photo-production of dissolved organic matter (mainly under UV radiation). In this paper, we show evidence for direct production of CO by phytoplankton and we suggest it as a significant mechanism for CO production in the ocean. Abstract. In order to investigate carbon monoxide (CO) emissions by phytoplankton organisms, a series of laboratory experiments was conducted in Kiel (Germany). Nine monocultures, including diatoms, coccolithophorids, chlorophytes and cyanobacteria have been characterised. This was done by following the CO variations from monoculture aliquots exposed to photosynthetically active radiation during one or two complete diurnal cycles. All the studied cultures have shown significant CO production when illuminated. Emission rates have been estimated to range from 1.4 × 10–5 to 8.7 × 10–4 μg of CO μg chlorophyll–1 h–1 depending on the species. When considering the magnitude of the emission rates from the largest CO emitters (cyanobacteria and diatoms), this biotic source could represent up to 20% of the CO produced in oceanic waters. As global models currently mainly consider CO production from the photo-degradation of dissolved organic matter, this study suggests that biotic CO production should also be taken into account. Whether this biological production might also contribute to some degree to the previous observed non-zero CO production below the euphotic zone (dark CO production) cannot be deduced here and needs to be further investigated.
Gypsum saturation degrees and precipitation potentials from Dead Sea - seawater mixtures
Authors: Reznik Itay J. , Ganor Jiwchar , Gal Assaf , Gavrieli Ittai
Published: October 2009

Environmental context. Since the 1960s the Dead Sea water level has dropped by nearly 30 m and over the last decade the rate of decline accelerated to over 1 m per year. Conveying seawater to the Dead Sea to stabilise or even raise its water level is currently being considered but may result in ‘whitening’ of the surface water through the formation of minute gypsum crystals that will remain suspended in the water column for a prolonged period of time. This paper is a first step in attaining the relevant physical and chemical parameters required to assess the potential for such whitening of the Dead Sea.
Abstract. Introduction of seawater to the Dead Sea (DS) to stabilise its level raises paramount environmental questions. A major concern is that massive nucleation and growth of minute gypsum crystals will occur as a result of mixing between the SO42–-rich Red Sea (RS) water and Ca2+-rich DS brine. If the gypsum will not settle quickly to the bottom it may influence the general appearance of the DS by ‘whitening’ the surface water. Experimental observations and theoretical calculations of degrees of saturation with respect to gypsum (DSG) and gypsum precipitation potentials (PPT) were found to agree well, over the large range but overall high ionic strength of DS–RS mixtures. The dependency of both DSG and PPT on temperature was examined as well. Based on our thermodynamic insights, slow discharge of seawater to the DS will result in a relatively saline upper water column which will lead to enhanced gypsum precipitation.
Photodegradation of nitrite in lake waters: role of dissolved organic matter
Authors: Vione Davide , Minella Marco , Minero Claudio , Maurino Valter , Picco Paolo , Marchetto Aldo , Tartari Gabriele
Published: October 2009

Environmental context. Nitrite is an important nutrient in surface waters, a key intermediate in the interconversion of nitrate into ammonium, and a considerable photochemical source of reactive species such as the hydroxyl radical. We have found that scavengers of hydroxyl radicals such as dissolved organic matter, which are usually supposed to inhibit the photodegradation of dissolved compounds, are able on the contrary to enhance the phototransformation of nitrite. The three weeks’ lifetime of nitrite in the surface layer of lakes, derived from the results of the present work, would make photochemistry an important issue in determining the concentration of nitrite in lake water.
Abstract. Here we studied the degradation rate of nitrite (NO2–), added to lake water at sub-micromolar levels, upon ultraviolet (UV) irradiation. NO2– photodegradation was considerably faster in lake water compared with ultra-pure water. A key issue was the presence in lake water of hydroxyl radical (•OH) scavengers that inhibited the reaction between NO2– and •OH. Such a reaction, while causing additional NO2– transformation, produced nitrogen dioxide (NO2•) that was subsequently involved into the regeneration of NO2– by dimerisation or the reaction with nitric oxide (NO•). The scavenging of •OH by compounds different from NO2– (mainly dissolved organic matter, DOM) prevented the regeneration reactions from taking place, and enhanced the phototransformation of NO2–. Model calculations for the direct photolysis of NO2–, applied to the lake water samples, yielded a NO2– half-life time of around three weeks in the mixing layer of the lakes because of photodegradation. Therefore, we conclude that photodegradation is a potentially important process to control the concentration of NO2– in shallow lakes, or in deeper ones under stratification conditions.
Development of DNPH/HPLC method for the measurement of carbonyl compounds in the aqueous phase: applications to laboratory simulation and field measurement
Authors: Wang Hongli , Zhang Xuan , Chen Zhongming
Published: October 2009

Environmental context. Carbonyl compounds, a class of oxygenated organic matter, are crucial participants in atmospheric processes. Recently, studies have shown that the aqueous-phase processes of carbonyls have an important contribution to the formation of secondary organic aerosol (SOA), which is considered to have a significant impact on global climate change and human health. We developed the classical DNPH/HPLC method to characterise the aqueous-phase carbonyls, especially methacrolein, methyl vinyl ketone, glyoxal, and methylglyoxal, which are important precursors of SOA, in order to better understand the pathways of SOA formation in the atmosphere.
Abstract. The DNPH/HPLC method for characterising monocarbonyls and dicarbonyls in the aqueous phase has been developed. A series of experiments have been carried out using eight atmospheric ubiquitous carbonyl compounds as model dissolved compounds in both acetonitrile and water solution to obtain the optimal derivatisation and analysis qualifications. Compared with the analysis of carbonyls dissolved in acetonitrile, the influence of acidity on the derivatisation efficiency should be carefully considered in determining carbonyls in water and the optimal acidity is pH 2.0. We find that methyl vinyl ketone (MVK) transforms to crotonaldehyde during the derivatisation reaction. This transformation can be controlled to a minor degree by increasing the mixing ratio of DNPH to MVK up to 100 : 1. This improved method has been satisfactorily applied to laboratory simulations and field measurements for better understanding the carbonyl chemistry in the atmosphere.
Ionic regulation in an alpine peatland in the Bogong High Plains, Victoria, Australia
Authors: Silvester Ewen
Published: October 2009

Environmental context. Australian alpine peatlands are thought to have an important role in maintaining water quality in the associated headwater streams. This study has confirmed that these peatlands can significantly modify stream water through a range of mechanisms, including: nutrient uptake, salt sequestering, and the export of organic carbon. While the significance of this chemical regulation to down stream processes is yet to be fully understood, it is clear that these systems have considerable potential to modify water composition.
Abstract. Heathy Spur 1 (HS-1) is an intact alpine peatland in the Bogong High Plains, Victoria, Australia, that serves as a reference system for understanding the impacts of historical land use practices (cattle grazing, water diversion) and wildfire. The major ion chemistry in the groundwater feed and drainage water at HS-1 was studied over seasonal timescales during ‘dry weather’ periods; conditions that allow a simple hydrological model to be used, where the groundwater is assumed to partition between evapotranspiration and stream discharge. With this model the acid neutralising capacity (ANC) of stream discharge can be understood in terms of evapotranspiration and proton uptake associated with nitrate and sulfate removal. Stream discharge ANC is strongly partitioned towards exported dissolved organic carbon, shifting the buffering intensity to lower pH compared to the groundwater. Given the extremely low alkalinity of the regional groundwater, these alpine peatlands likely have a critical role in increasing headwater stream buffering capacity.
Water uptake of humic and fulvic acid: measurements and modelling using single parameter Köhler theory
Authors: Hatch Courtney D. , Gierlus Kelly M. , Zahardis James , Schuttlefield Jennifer , Grassian Vicki H.
Published: October 2009

Environmental context. Humic and fulvic acids are macromolecular, multifunctional, polyacidic compounds that are important proxies for humic-like substances (HULIS), which are ubiquitous components of tropospheric particulate matter. The hygroscopic nature of these substances suggests that they can contribute to direct and indirect climate forcing. Thus, the effects of water uptake in humic-like particles in the atmosphere must be well understood.
Abstract. The water uptake of humic and fulvic acid aerosols was determined by hygroscopic tandem differential mobility analysis (hTDMA) and extinction Fourier transform infrared (FTIR) spectroscopy. Water uptake on humic and fulvic acid thin films was also investigated using attenuated total reflectance (ATR) FTIR spectroscopy. The hygroscopic growth of monodisperse, 100-nm (dry) Suwannee River fulvic acid (SRFA) and humic acid sodium salt (NaHA) aerosols was determined and modelled using Köhler theory. A single parameter, the ionic density (ρion), which contains physical properties that are not well established for these substances, was determined for SRFA and NaHA to be 2.1 × 10–3 and 7.0 × 10–3 mol cm–3 respectively. The hygroscopic growth was then modelled using the ρion-Köhler equation and the critical parameters determined. The critical percent supersaturation of SRFA and NaHA was determined to be 0.60 and 0.33% respectively using the surface tension of water; and 0.35 and 0.19% respectively using the surface tension of aqueous HULIS. κ-Köhler theory, was also used to calculate the critical supersaturation and was found to be in good agreement with the ρion representation. Both extinction FTIR of aerosols and ATR-FTIR absorption measurements of thin films confirm enhanced water uptake with increasing relative humidity (RH).
An aspartate and a water molecule mediate efficient acid-base catalysis in a tailored antibody pocket
Authors: Debler Erik W. , Müller Roger , Hilvert Donald , Wilson Ian A.
Published: October 2009

Design of catalysts featuring multiple functional groups is a desirable, yet formidable goal. Antibody 13G5, which accelerates the cleavage of unactivated benzisoxazoles, is one of few artificial enzymes that harness an acid and a base to achieve efficient proton transfer. X-ray structures of the Fab-hapten complexes of wild-type 13G5 and active-site variants now afford detailed insights into its mechanism. The parent antibody preorganizes Asp
H35
and Glu
L34
to abstract a proton from substrate and to orient a water molecule for leaving group stabilization, respectively. Remodeling the environment of the hydrogen bond donor with a compensatory network of ordered waters, as seen in the Glu
L34
to alanine mutant, leads to an impressive 10
9
-fold rate acceleration over the nonenzymatic reaction with acetate, illustrating the utility of buried water molecules in bifunctional catalysis. Generalization of these design principles may aid in creation of catalysts for other important chemical transformations.
Downregulating the sucrose transporter
VpSUT1
in
Verbascum phoeniceum
does not inhibit phloem loading
Authors: Zhang Cankui , Turgeon Robert
Published: October 2009

Sucrose is loaded into the phloem in the minor veins of leaves before export. Two active, species-specific loading mechanisms have been proposed. One involves transporter-mediated sucrose transfer from the apoplast into the sieve element-companion cell complex, so-called apoplastic loading. In the putative second mechanism, sucrose follows an entirely symplastic pathway, and the solute concentration is elevated by the synthesis of raffinose and stachyose in the phloem, not by transporter activity. Several sucrose-transporting plants have been shown to be apoplastic loaders by downregulating
sucrose transporter 1
(
SUT1
), leading to accumulation of sugars and leaf chlorosis. In this study we compared the effect of downregulating
SUT1
in
Nicotiana tabacum
, a sucrose transporter, and
Verbascum phoeniceum
, a species that transports raffinose and stachyose. To test the effectiveness of RNAi downregulation, we measured
SUT1
mRNA levels and sucrose-H
+
symport in leaf discs. Mild
NtSUT1
downregulation in
N. tabacum
resulted in the pronounced phenotype associated with loading inhibition. In contrast, no such phenotype developed when
VpSUT1
was downregulated in
V. phoeniceum
, leaving minimal sucrose transport activity. Only those plants with the most severe
VpSUT1
downregulation accumulated more carbohydrate than usual and these plants were normal by other criteria: growth rate, photosynthesis, and ability to clear starch during the night. The results provide direct evidence that the mechanism of phloem loading in
V. phoeniceum
does not require active sucrose uptake from the apoplast and strongly supports the conclusion that the loading pathway is symplastic in this species.
Resolving the evolution of extant and extinct ruminants with high-throughput phylogenomics
Authors: Decker Jared E. , Pires J. Chris , Conant Gavin C. , McKay Stephanie D. , Heaton Michael P. , Chen Kefei , Cooper Alan , Vilkki Johanna , Seabury Christopher M. , Caetano Alexandre R. , Johnson Gary S. , Brenneman Rick A. , Hanotte Olivier , Eggert Lori S. , Wiener Pamela , Kim Jong-Joo , Kim Kwan Suk , Sonstegard Tad S. , Van Tassell Curt P. , Neibergs Holly L. , McEwan John C. , Brauning Rudiger , Coutinho Luiz L. , Babar Masroor E. , Wilson Gregory A. , McClure Matthew C. , Rolf Megan M. , Kim JaeWoo , Schnabel Robert D. , Taylor Jeremy F.
Published: October 2009

The Pecorans (higher ruminants) are believed to have rapidly speciated in the Mid-Eocene, resulting in five distinct extant families: Antilocapridae, Giraffidae, Moschidae, Cervidae, and Bovidae. Due to the rapid radiation, the Pecoran phylogeny has proven difficult to resolve, and 11 of the 15 possible rooted phylogenies describing ancestral relationships among the Antilocapridae, Giraffidae, Cervidae, and Bovidae have each been argued as representations of the true phylogeny. Here we demonstrate that a genome-wide single nucleotide polymorphism (SNP) genotyping platform designed for one species can be used to genotype ancient DNA from an extinct species and DNA from species diverged up to 29 million years ago and that the produced genotypes can be used to resolve the phylogeny for this rapidly radiated infraorder. We used a high-throughput assay with 54,693 SNP loci developed forBos taurus taurusto rapidly genotype 678 individuals representing 61 Pecoran species. We produced a highly resolved phylogeny for this diverse group based upon 40,843 genome-wide SNP, which is five times as many informative characters as have previously been analyzed. We also establish a method to amplify and screen genomic information from extinct species, and placeBison priscuswithin the Bovidae. The quality of genotype calls and the placement of samples within a well-supported phylogeny may provide an important test for validating the fidelity and integrity of ancient samples. Finally, we constructed a phylogenomic network to accurately describe the relationships between 48 cattle breeds and facilitate inferences concerning the history of domestication and breed formation.
Structural basis for the high Ca
2+
affinity of the ubiquitous SERCA2b Ca
2+
pump
Authors: Vandecaetsbeek Ilse , Trekels Mieke , De Maeyer Marc , Ceulemans Hugo , Lescrinier Eveline , Raeymaekers Luc , Wuytack Frank , Vangheluwe Peter
Published: October 2009

Sarco(endo)plasmic reticulum Ca
2+
ATPase (SERCA) Ca
2+
transporters pump cytosolic Ca
2+
into the endoplasmic reticulum, maintaining a Ca
2+
gradient that controls vital cell functions ranging from proliferation to death. To meet the physiological demand of the cell, SERCA activity is regulated by adjusting the affinity for Ca
2+
ions. Of all SERCA isoforms, the housekeeping SERCA2b isoform displays the highest Ca
2+
affinity because of a unique C-terminal extension (2b-tail). Here, an extensive structure–function analysis of SERCA2b mutants and SERCA1a2b chimera revealed how the 2b-tail controls Ca
2+
affinity. Its transmembrane (TM) segment (TM11) and luminal extension functionally cooperate and interact with TM7/TM10 and luminal loops of SERCA2b, respectively. This stabilizes the Ca
2+
-bound E1 conformation and alters Ca
2+
-transport kinetics, which provides the rationale for the higher apparent Ca
2+
affinity. Based on our NMR structure of TM11 and guided by mutagenesis results, a structural model was developed for SERCA2b that supports the proposed 2b-tail mechanism and is reminiscent of the interaction between the α- and β-subunits of Na
+
,K
+
-ATPase. The 2b-tail interaction site may represent a novel target to increase the Ca
2+
affinity of malfunctioning SERCA2a in the failing heart to improve contractility.
Epidemiology and Outcomes of Hospitalizations with Complicated Skin and Skin-Structure Infections: Implications of Healthcare-Associated Infection Risk Factors
Authors: Zilberberg Marya D. , Shorr Andrew F. , Micek Scott T. , Hoban Alex P. , Pham Victor , Doherty Joshua A. , Ramsey Andrew M. , Kollef Marin H.
Published: October 2009

Objective.

Healthcare-associated infections are likely to be caused by drug-resistant and possibly mixed organisms and to be treated with inappropriate antibiotics. Because prompt appropriate treatment is associated with better outcomes, we studied the epidemiology of healthcare-associated complicated skin and skin-structure infections (cSSSIs).

Patients.

Persons hospitalized with cSSSI and a positive culture result.

Methods.

We conducted a single-center retrospective cohort study from April 2006 through December 2007. We differentiated healthcare-associated from community-acquired cSSSIs by at least 1 of the following risk factors: (1) recent hospitalization, (2) recent antibiotics, (3) hemodialysis, and (4) transfer from a nursing home. Inappropriate treatment was defined as no antimicrobial therapy with activity against the offending pathogen(s) within 24 hours after collection of a culture specimen. Mixed infections were those caused by both a gram-positive and a gram-negative organism.

Results.

Among 717 hospitalized patients with cSSSI, 527 (73.5%) had healthcare-associated cSSSI. Gram-negative organisms were more common (relative risk, 1.24 [95% confidence interval, 1.14–1.35) and inappropriate treatment trended toward being more common (odds ratio, 1.29 [95% confidence interval, 0.85–1.95]) in healthcare-associated cSSSI than in community-acquired cSSSI. Mixed cSSSIs occurred in 10.6% of patients with healthcare-associated cSSSI and 6.3% of those with community-acquired cSSSI (P = .082) and were more likely to be treated inappropriately than to be nonmixed infections (odds ratio, 2.42 [95% confidence interval, 1.43–4.10]). Both median length of hospital stay (6.2 vs 2.9 days; P < .001) and mortality rate (6.6% vs 1.1%; P = .003) were significantly higher for healthcare-associated cSSSI than community-acquired cSSSI.

Conclusions.

Healthcare-associated cSSSIs are common and are likely to be caused by gram-negative organisms. Mixed infections carry a <2-fold greater risk of inappropriate treatment. Healthcare-associated cSSSIs are associated with increased mortality and prolonged length of hospital stay, compared with community-acquired cSSSIs.
Molecular Epidemiology of Invasive Aspergillosis: Lessons Learned from an Outbreak Investigation in an Australian Hematology Unit
Authors: Kidd Sarah E. , Ling Li Min , Meyer Wieland , Morrissey C. Orla , Chen Sharon C. A. , Slavin Monica A.
Published: October 2009

Suspected nosocomial Aspergillus fumigatus infections in an Australian hematology unit were investigated by molecular typing of clinical and environmental isolates using polymerase chain reaction fingerprinting, CSP typing, and multilocus microsatellite typing. Only multilocus microsatellite typing revealed that all isolates were genetically distinct. The selection of an appropriate typing method is essential for effective outbreak investigations.
Subcritical crack growth law and its consequences for lifetime statistics and size effect of quasibrittle structures
Authors: Le Jia-Liang , Bažant Zdeněk P , Bazant Martin Z
Published: October 2009

For brittle failures, the probability distribution of structural strength and lifetime are known to be Weibullian, in which case the knowledge of the mean and standard deviation suffices to determine the loading or time corresponding to a tolerable failure probability such as 10−6. Unfortunately, this is not so for quasibrittle structures, characterized by material inhomogeneities that are not negligible compared with the structure size (as is typical, e.g. for concrete, fibre composites, tough ceramics, rocks and sea ice). For such structures, the distribution of structural strength was shown to vary from almost Gaussian to Weibullian as a function of structure size (and also shape). Here we predict the size dependence of the distribution type for the lifetime of quasibrittle structures. To derive the lifetime statistics from the strength statistics, the subcritical crack growth law is requisite. This empirical law is shown to be justified by fracture mechanics of random crack jumps in the atomic lattice and the condition of equality of the energy dissipation rates calculated on the nano-scale and the macro-scale. The size effect on the lifetime is found to be much stronger than that on the structural strength. The theory is shown to match the experimentally observed systematic deviations of lifetime histograms from the Weibull distribution.
Distinct Roles for CARMIL Isoforms in Cell Migration
Authors: Liang Yun , Niederstrasser Hanspeter , Edwards Marc , Jackson Charles E. , Cooper John A.
Published: October 2009

Molecular mechanisms for cell migration, especially how signaling and cytoskeletal systems are integrated, are not understood well. Here, we examined the role of CARMIL (capping protein, Arp2/3, and Myosin-I linker) family proteins in migrating cells. Vertebrates express three conserved genes for CARMIL, and we examined the functions of the two CARMIL genes expressed in migrating human cultured cells. Both isoforms, CARMIL1 and 2, were necessary for cell migration, but for different reasons. CARMIL1 localized to lamellipodia and macropinosomes, and loss of its function caused loss of lamellipodial actin, along with defects in protrusion, ruffling, and macropinocytosis. CARMIL1-knockdown cells showed loss of activation of Rac1, and CARMIL1 was biochemically associated with the GEF Trio. CARMIL2, in contrast, colocalized with vimentin intermediate filaments, and loss of its function caused a distinctive multipolar phenotype. Loss of CARMIL2 also caused decreased levels of myosin-IIB, which may contribute to the polarity phenotype. Expression of one CARMIL isoform was not able to rescue the knockdown phenotypes of the other. Thus, the two isoforms are both important for cell migration, but they have distinct functions.
Notch Signaling and Developmental Cell-Cycle Arrest in Drosophila Polar Follicle Cells
Authors: Shyu Li-Fang , Sun Jianjun , Chung Hui-Min , Huang Yi-Chun , Deng Wu-Min
Published: October 2009

Temporal and spatial regulation of cell division is critical for proper development of multicellular organisms. An important aspect of this regulation is cell-cycle arrest, which in many cell types is coupled with differentiated status. Here we report that the polar cells—a group of follicle cells differentiated early during Drosophila oogenesis—are arrested at G2 phase and can serve as a model cell type for investigation of developmental regulation of cell-cycle arrest. On examining the effects of String, a mitosis-promoting phosphatase Cdc25 homolog, and Notch signaling in polar cells, we found that misexpression of String can trigger mitosis in existing polar cells to induce extra polar cells. Normally, differentiation of the polar cells requires Notch signaling. We found that the Notch-induced extra polar cells arise through recruitment of the neighboring cells rather than promotion of proliferation, and they are also arrested at G2 phase. Notch signaling is probably involved in down-regulating String in polar cells, thus inducing the G2 cell-cycle arrest.
Binding the Atypical RA Domain of Ste50p to the Unfolded Opy2p Cytoplasmic Tail Is Essential for the High-Osmolarity Glycerol Pathway
Authors: Ekiel Irena , Sulea Traian , Jansen Gregor , Kowalik Maria , Minailiuc Ovidiu , Cheng Jing , Harcus Doreen , Cygler Miroslaw , Whiteway Malcolm , Wu Cunle
Published: October 2009

Activation of the high-osmolarity glycerol (HOG) pathway for osmoregulation in the yeast Saccharomyces cerevisiae involves interaction of the adaptor Ste50p with the cytoplasmic tail of single-transmembrane protein Opy2p. We have determined the solution structure of the Ste50p-RA (Ras association) domain, and it shows an atypical RA fold lacking the β1 and β2 strands of the canonical motif. Although the core of the RA domain is fully functional in the pheromone response, an additional region is required for the HOG pathway activation. Two peptide motifs within the intrinsically disordered cytoplasmic tail of Opy2p defined by NMR spectroscopy physically interact with the Step50p-RA domain. These Opy2p-derived peptides bind overlapping regions of the Step50p-RA domain with similarly weak affinities, suggesting a multivalent interaction of these proteins as a crucial point of control of the HOG pathway. As well, overall selection of signaling pathways depends on functionally distinct regions of the Ste50p-RA domain, implicating this element in the control of global regulatory decisions.