bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic expression patterns of RhoV/Chp and RhoU/Wrch during chicken embryonic development
Authors: Notarnicola Cécile , Le Guen Ludovic , Fort Philippe , Faure Sandrine , de Santa Barbara Pascal 
Published: March 2008

AbstractRho GTPases play central roles in the control of cell adhesion and migration, cell cycle progression, growth, and differentiation. However, although most of our knowledge of Rho GTPase function comes from the study of the three classic Rho GTPases RhoA, Rac1, and Cdc42, recent studies have begun to explore the expression, regulation, and function of some of the lesser‐known members of the Rho GTPase family. In the present study, we cloned the avian orthologues of RhoV (or Chp for Cdc42 homologous protein) and RhoU (or Wrch‐1 for Wnt‐regulated Cdc42 homolog‐1) and examined their expression patterns by in situ hybridization analysis both during early chick embryogenesis and later on, during gastrointestinal tract development. Our data show that both GTPases are detected in the primitive streak, the somites, the neural crest cells, and the gastrointestinal tract with distinct territories and/or temporal expression windows. Although both proteins are 90% identical, our results indicate that cRhoV and cRhoU are distinctly expressed during chicken embryonic development. Developmental Dynamics 237:1165–1171, 2008. © 2008 Wiley‐Liss, Inc.
Identification of genes controlled by LMX1B in the developing mouse limb bud
Authors: Krawchuk Dayana , Kania Artur 
Published: March 2008

AbstractIn the developing limb, dorsal–ventral patterning is controlled by the transcription factor LMX1B, expressed in the dorsal mesenchyme. Loss of Lmx1b function in mice or humans results in the loss of dorsal limb structures and Nail–Patella syndrome, but the effectors through which LMX1B controls limb patterning are virtually unknown. Using microarrays to analyze the differential expression of mRNAs in wild‐type vs. Lmx1b−/− limb buds, we have identified hundreds of genes as putative LMX1B targets. Analysis of a subset of these candidates by in situ mRNA localization has identified eight genes previously unknown to require Lmx1b for their dorsal–ventral restriction of expression in the limb. Furthermore, our results suggest that LMX1B controls different targets along the proximal–distal axis of the limb, and suggest the existence of a dorsal proximal limb region that is rich in mRNAs requiring Lmx1b for their expression. Developmental Dynamics 237:1183–1192, 2008. © 2008 Wiley‐Liss, Inc.
Efficient Preparation of [1‐15N]‐3‐Cyano‐4‐methyl‐1H‐pyrrole by a Wittig‐Based Strategy
Authors: Dawadi Prativa B. S. , Lugtenburg Johan 
Published: March 2008

Abstract3‐Cyano‐4‐methyl‐1H‐pyrrole (1) was prepared by a new Wittig procedure from simple, commercially available starting materials in four steps with an overall yield of 39 %. Similarly, [1‐15N]‐3‐cyano‐4‐methyl‐1H‐pyrrole (1a) was prepared starting from [15N]‐phthalimide. In this synthesis, Wittig coupling was used to form the central C–C bond of intermediate 6, which has nitrile and methyl substituents. Upon deprotection and cyclization pyrrole 1 is obtained directly in one pot. This scheme also allows stable isotope incorporation at any position or a combination of positions. 3‐Cyano‐4‐methyl‐1H‐pyrrole was converted into the novel 1‐benzyl‐3‐cyano‐4‐methylpyrrole and the novel 4‐methyl‐1H‐pyrrole‐3‐aldehyde. It is clear that this novel Wittig procedure has a wide scope that will allow the easy preparation of many new pyrrole systems.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Simulating hydrostatic and non‐hydrostatic oceanic flows
Authors: Iskandarani M. 
Published: March 2008

AbstractThe thin aspect ratio of oceanic basins is simultaneously a complication to contend with when developing ocean models and an opportunity to simplify the equations of motion. Here we discuss these two aspects of this geometric feature in the context of hydrostatic and non‐hydrostatic ocean models. A simple analysis shows that the horizontal viscous operator in the hydrostatic primitive equations plays a central role in the specification of boundary conditions on the lateral vertical surfaces bounding the domain. The asymptotic analysis shows that for very thin aspect ratios the leading‐order flow cannot be closed unless additional terms in the equations are considered, namely either the horizontal viscous forces or the non‐hydrostatic pressure forces. In either case, narrow boundary layers must be resolved in order to close the circulation properly. The computational cost increases substantially when non‐hydrostatic effects are taken into account. Copyright © 2008 John Wiley & Sons, Ltd.
Insertion of Molecular Oxygen in Transition‐Metal Hydride Bonds, Oxygen‐Bond Activation, and Unimolecular Dissociation of Metal Hydroperoxide Intermediates. Short Communication
Authors: Schlangen Maria , Schwarz Helmut 
Published: March 2008

AbstractThermal activation of molecular oxygen is observed for the late‐transition‐metal cationic complexes [M(H)(OH)]+ with M=Fe, Co, and Ni. Most of the reactions proceed via insertion in a metalhydride bond followed by the dissociation of the resulting metal hydroperoxide intermediate(s) upon losses of O, OH, and H2O. As indicated by labeling studies, the processes for the Ni complex are very specific such that the O‐atoms of the neutrals expelled originate almost exclusively from the substrate O2. In comparison to the [M(H)(OH)]+ cations, the ionmolecule reactions of the metal hydride systems [MH]+ (M=Fe, Co, Ni, Pd, and Pt) with dioxygen are rather inefficient, if they occur at all. However, for the solvated complexes [M(H)(H2O)]+ (M=Fe, Co, Ni), the reaction with O2 involving OO bond activation show higher reactivity depending on the transition metal: 60% for the Ni, 16% for the Co, and only 4% for the Fe complex relative to the [Ni(H)(OH)]+/O2 couple.
New Sesquiterpene Formamides from the Marine Sponge Axinyssa sp.
Authors: Lan Wen‐Jian , Wan Hong‐Ping , Li Guo‐Xi , Li Hou‐Jin , Chen Yun‐Yun , Liao Cheng‐Zhu , Cai Ji‐Wen 
Published: March 2008

AbstractChemical investigation of an extract of the marine sponge Axinyssa sp., collected from the South China Sea, led to the isolation and identification of two new sesquiterpene formamides, (4R*,5R*,10R*)‐4‐formamidoeudesm‐7‐ene (1) and (4R*,5R*,7S*,10R*)‐4‐formamidoeudesman‐11‐ol (2), together with the known 4α‐formamidogorgon‐11‐ene (3). Their structures were elucidated by spectroscopic methods, including 1D‐ and 2D‐NMR spectroscopy, high‐resolution ESI‐TOF mass spectrometry, as well as X‐ray single‐crystal diffraction experiments. Possible biosynthetic pathways for 1–3 were also proposed. The human nasopharyngeal cancer cell line CNE‐2, human cervical cancer cell line HeLa, and human normal liver cell line L02 were used to examine the cytotoxic activities of 1–3 in vitro. As the results, 1 showed significant cytotoxic activity against CNE‐2, HeLa, and L02 cell lines with the IC50 values of 13.8, 7.5, and 38.0 μg/ml, resp.
Noroleanane Triterpenoids from the Aerial Parts of Lantana camara
Authors: Begum Sabira , Zehra Syeda Qamar , Hassan Syed Imran , Siddiqui Bina S. 
Published: March 2008

AbstractTwo novel triterpenoids, lantadienone (1) and camaradienone (2), were isolated from the aerial parts of Lantana camara, along with seven known compounds, lantadene A, lantadene B, β‐sitosterol 3‐(β‐D‐glucopyranoside), camaric acid, lantanilic acid, lantanolic acid, and camangeloyl acid. Their structures were elucidated as (3β,22β)‐3,25‐epoxy‐3‐hydroxy‐22‐{[(2Z)‐2‐methyl‐1‐oxobut‐2‐enyl]oxy}‐28‐noroleana‐12,17‐dien‐11‐one (1) and (3β)‐3,25‐epoxy‐3‐hydroxy‐28‐noroleana‐12,17‐dien‐11‐one (2), respectively, by means of spectral studies. The triterpenoids 1 and 2 represent 28‐noroleananes oxidized at C(11) and C(22) or at C(11), reported for the first time.
Physicochemical Profiling of Sartans: A Detailed Study of Ionization Constants and Distribution Coefficients
Authors: Tosco Paolo , Rolando Barbara , Fruttero Roberta , Henchoz Yveline , Martel Sophie , Carrupt Pierre‐Alain , Gasco Alberto 
Published: March 2008

AbstractA detailed investigation of the ionization and lipophilicity profiles of selected sartans (valsartan, losartan, irbesartan, candesartan, candesartan cilexetil), a class of antihypertensives commonly used in therapy, is presented. The pKa macroconstants were determined by integrated potentiometry, capillary electrophoresis, and UV spectrophotometry. The measured pKa macroconstants were connected with the ionizable centers present in each molecule with the aid of model compounds. Potentiometric titrations with the GLpKa apparatus were performed to determine the distribution profile (log D vs. pH) of valsartan, while the shake‐flask procedure was used to characterize the distribution profile of the other compounds. Valsartan showed a lipophilicity profile consistent with the presence of two acidic centers. Losartan and irbesartan, which contain one acidic and one basic center, displayed the classical bell‐shaped profile of ordinary ampholytes. By contrast, a more complex situation emerged in the case of candesartan, due to the large number of ionization equilibria involved. The low solubility of candesartan cilexetil, together with the ease of hydrolysis of the ester moiety, prevented a successful investigation of its ionization and lipophilicity profiles.
New Oxygenated Lignans from Kadsura philippinensis
Authors: Shen Ya‐Ching , Lin Yu‐Chi , Cheng Yuan‐Bin , Chang Chia‐Ju , Lan Ting‐Wei , Liou Shorong‐Shii , Chien Ching‐Te , Liaw Chia‐Ching , Khalil Ashraf Taha 
Published: March 2008

AbstractSeven new oxygenated lignans, kadsuphilins G–M (1–7, resp.), were isolated by chromatographic fractionation of an AcOEt extract of the aerial part of Kadsura philippinensis including four compounds with a dibenzocyclooctadiene skeleton, two with a bicyclooctane ring system, and one of 1,4‐biphenyldimethylbutane type. The structures of the isolated compounds were elucidated through extensive spectroscopic analyses, particularly 2D‐NMR experiments (HMQC, HMBC, and NOESY). The configuration of the chiral centers and the biphenyl moiety were determined by NOESY as well as CD spectroscopy, respectively.
Novel Bibenzyl Derivatives from the Tubers of Bletilla striata
Authors: Feng Jia‐Quan , Zhang Ru‐Jun , Zhao Wei‐Min 
Published: March 2008

AbstractThree novel bibenzyl derivatives, blestritins A–C (1–3), along with 18 known constituents, were isolated from the tubers of Bletilla striata (Orchidaceae), a traditional Chinese medicine used for the treatment of tuberculosis and haemorrhage of the stomach and lungs. Their structures were identified on the basis of spectroscopic analyses.
An Oxidative Rearrangement of 6‐Phenylbicyclo[3.2.0]heptan‐6‐ol to 1,1′‐Biphenyl‐Carbaldehydes: A Mechanistic Study
Authors: Ceylan Mustafa , Fındık Esra , Seçen Hasan 
Published: March 2008

AbstractAcid‐catalyzed rearrangement of 6‐phenylbicyclo[3.2.0]heptan‐6‐ol gave 1,1′‐biphenyl and 1,1′‐biphenyl‐carbaldehydes in small amounts as well as the expected rearrangement products. A detailed study of the reaction mechanism revealed that the conversion occurs via an oxidative process through the consecutive formation of cycloheptadienes, cycloheptatrienes, and 1,1′‐biphenyls. The acid‐catalyzed rearrangement of 6‐phenylbicyclo[3.2.0]hept‐2‐en‐6‐ols gave 1‐ and 2‐phenylcycloheptatrienes directly, from which 1,1′‐biphenyl and 1,1′‐biphenyl‐carbaldehydes were obtained by oxidation.
Macrorhynines A and B, Two Novel Norditerpenoid Alkaloids from Aconitum macrorhynchum
Authors: Yang Xiao‐Dong , Yang Shu , Yang Jin , Zhao Jing‐Feng , Zhang Hong‐Bin , Li Liang 
Published: March 2008

AbstractTwo novel norditerpenoid alkaloids, macrorhynines A and B (1 and 2), together with seven known compounds, were isolated from Aconitum macrorhynchum. The structures of the new compounds were elucidated as (1α,6α,14α)‐8‐acetoxy‐1,6,16‐trimethoxy‐4‐(methoxymethyl)aconitan‐14‐yl 4‐methoxybenzoate (1) and (1α,6α,14α)‐8‐acetoxy‐13‐hydroxy‐1,6,16‐trimethoxy‐4‐(methoxymethyl)aconitan‐14‐yl 4‐methoxybenzoate (2) on the basis of spectral analyses. The novel compounds were found to contain the rare C(19)N, azomethine, group.
Effect of water table drawdown on peatland dissolved organic carbon export and dynamics
Authors: Strack M. , Waddington J. M. , Bourbonniere R. A. , Buckton E. L. , Shaw K. , Whittington P. , Price J. S. 
Published: March 2008

AbstractPeatlands play an important role in the global carbon cycle, and loss of dissolved organic carbon (DOC) has been shown to be important for peatland carbon budgets. The objective of this study was to determine how net production and export of DOC from a northern peatland may be affected by disturbance such as drainage and climate change.The study was conducted at a poor fen containing several pool–ridge complexes: (1) control site–no water table manipulation; (2) experimental site–monitored for one season in a natural state and then subjected to a water table drawdown for 3 years; (3) drained site–subjected to a water table drawdown 9 years prior to monitoring. The DOC concentration was measured in pore water along a microtopographic gradient at each site (hummock, lawn and hollow), in standing water in pools, and in discharge from the experimental and drained sites. The initial water table drawdown released ∼3 g of carbon per square metre in the form of DOC, providing a large pulse of DOC to downstream ecosystems. This value, however, represents only 1–9% of ecosystem respiration at this site. Seasonal losses of DOC following drainage were 8–11 g of carbon per square metre, representing ∼17% of the total carbon exchange at the experimental study site. Immediately following water table drawdown, DOC concentrations were elevated in pore water and open water pools. In subsequent seasons, DOC concentration in the pool declined, but remained higher than the control site even 11 years after water‐table drawdown. This suggests continued elevated net DOC production under lower water table conditions likely related to an increase in vegetation biomass and larger water table fluctuations at the experimental and drained sites. However, the increase in concentration was limited to initially wet microforms (lawns and hollows) reflecting differences in vegetation community changes, water table and soil subsidence along the microtopographic gradient. Copyright © 2008 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.
Spatial and temporal perspectives on spring break‐up flooding in the Slave River Delta, NWT
Authors: Brock B. E. , Wolfe B. B. , Edwards T. W. D. 
Published: March 2008

AbstractSpatial and temporal patterns of spring break‐up flooding in the Slave River Delta (SRD), Northwest Territories, are characterized during three years (2003–2005) using water isotope tracers and total inorganic suspended sediment (TSS) concentrations measured from lakewater samples collected shortly after the spring melt. Strongly contrasting spring melt periods led to a moderate flood in 2003, no flooding in 2004 and widespread flooding in 2005. Flooded lakes have isotopically‐depleted δ18O (δ2H) signatures, ranging between − 19·2‰ (−145‰) and − 17·1‰ (−146‰) and most have high TSS concentrations (>10 mg L−1), while non‐flooded lakes have more isotopically‐enriched δ18O (δ2H) signatures, ranging between − 18·2‰ (−149‰) and − 10·6‰ (−118‰) and low TSS concentrations (<10 mg L−1). These results, in conjunction with the isotopic signatures of Slave River water and snowmelt, are used to estimate the proportion of river‐ or snowmelt‐induced dilution in delta lakes during the spring of each study year. Calculations indicate river flooding caused dilution of ∼70–100% in delta lakes, while snowmelt dilution in the absence of river flooding ranged from ∼0–56%. A positive relationship exists between the spatial extent of spring flooding in the SRD and level and discharge on the Slave River and upstream tributaries, suggesting that upstream flow generation plays a key role in determining the magnitude of spring flooding in the SRD. Parallel variations in the 46‐year instrumental Slave River discharge record and flood stratigraphy in the active delta indicate that there is potential for extending the flood history of the SRD, a development that will contribute to a more robust understanding of the drivers of historic, contemporary and future flood frequency in the delta. Copyright © 2008 John Wiley & Sons, Ltd.
Predicting longitudinal dispersion coefficient in natural streams by artificial intelligence methods
Authors: Toprak Z. Fuat , Cigizoglu Hikmet Kerem 
Published: March 2008

AbstractIn this study, three artificial neural network methods, i.e. feed forward back propagation, the radial basis function neural network, and the generalized regression neural network are employed to compute the longitudinal dispersion coefficient in order to evaluate its behaviour in predicting dispersion characteristics in natural streams. These methods, which use hydraulic and geometrical data to predict dispersion coefficients, can easily be applied to natural streams and are proven to be superior in explaining their dispersion characteristics more precisely than existing equations. This method of predicting the longitudinal dispersion coefficient in river flows was tested on 65 data sets, obtained by researchers from 30 rivers in the USA. Results using the models are compared with results obtained in many other studies, and are shown to be more accurate than the other methods considered. Copyright © 2008 John Wiley & Sons, Ltd.
Delineating runoff processes and critical runoff source areas in a pasture hillslope of the Ozark Highlands
Authors: Leh M. D. , Chaubey I. , Murdoch J. , Brahana J. V. , Haggard B. E. 
Published: March 2008

AbstractThe identification of runoff contributing areas would provide the ideal focal points for water quality monitoring and Best Management Practice (BMP) implementation. The objective of this study was to use a field‐scale approach to delineate critical runoff source areas and to determine the runoff mechanisms in a pasture hillslope of the Ozark Highlands in the USA. Three adjacent hillslope plots located at the Savoy Experimental Watershed, north‐west Arkansas, were bermed to isolate runoff. Each plot was equipped with paired subsurface saturation and surface runoff sensors, shallow groundwater wells, H‐flumes and rain gauges to quantify runoff mechanisms and rainfall characteristics at continuous 5‐minute intervals. The spatial extent of runoff source areas was determined by incorporating sensor data into a geographic information‐based system and performing geostatistical computations (inverse distance weighting method). Results indicate that both infiltration excess runoff and saturation excess runoff mechanisms occur to varying extents (0–58% for infiltration excess and 0–26% for saturation excess) across the plots. Rainfall events that occurred 1–5 January 2005 are used to illustrate the spatial and temporal dynamics of the critical runoff source areas. The methodology presented can serve as a framework upon which critical runoff source areas can be identified and managed for water quality protection in other watersheds. Copyright © 2008 John Wiley & Sons, Ltd.
Hydrologic prediction for urban watersheds with the Distributed Hydrology–Soil–Vegetation Model
Authors: Cuo Lan , Lettenmaier Dennis P. , Mattheussen Bernt V. , Storck Pascal , Wiley Matthew 
Published: March 2008

AbstractSome relatively straightforward modifications to the Distributed Hydrology–Soil–Vegetation Model (DHSVM) are described that allow it to represent urban hydrological processes. In the modified model, precipitation that falls on impervious surfaces becomes surface runoff, and a spatially varying (depending on land cover) fraction of surface runoff is connected directly to the stream channel, with the remainder stored and slowly released to represent the effects of stormwater detention. The model was evaluated through application to Springbrook Creek watershed in a partially urbanized area of King County, Washington. With calibration, the modified DHSVM simulates hourly streamflow from these urbanized catchments quite well. It is also shown how the revised model can be used to study the effects of continuing urbanization in the much larger Puget Sound basin. Model simulations confirm many previous studies in showing that urbanization increases peak flows and their frequency, and decreases peak flow lag times. The results show that the urbanization parameterizations for DHSVM facilitate use of the model for prediction and/or reconstruction of a range of historic and future changes in land cover that will accompany urbanization as well as other forms of vegetation change. Copyright © 2008 John Wiley & Sons, Ltd.
Growing season energy and water exchange from an oil sands overburden reclamation soil cover, Fort McMurray, Alberta, Canada
Authors: Carey Sean K. 
Published: March 2008

AbstractThe oil sands mining industry in Canada is required to return mining areas to a land capability equivalent to that which existed prior to mining. During the reclamation process, ecosystems are created that bear little similarity to boreal forests that existed prior to mining. Quantifying the water balance of reclaimed ecosystems is critical in establishing whether there is sufficient moisture for vegetation growth and in the fate of salts, which can be toxic when drawn to the surface or leached out of the covers. At Syncrude Canada Ltd's Mildred Lake mine north of Fort McMurray, Alberta, the surface energy balance was measured atop a reclaimed saline‐sodic overburden pile during three growing seasons using eddy covariance. At the onset of the study, the dominant vegetation was foxtail barley, which changed to sweet clover in 2004, and a low‐density species mix in 2005, including some aspen and white spruce seedlings. The 2005 growing season was cooler and wetter than 2003 and 2004, and there were seasonal differences in the delivery of precipitation among years. There were distinct differences in the surface energy balance among the study years related to weather, soil moisture, vegetation and stage of growth. Latent heat was the largest consumer of energy in 2003, and mid‐day fluxes of sensible and latent heat were approximately equal. In 2004, sensible heat became the dominant flux, primarily due to prolonged dry periods, whereas the wet 2005 season had the greatest latent heat flux density of any year. Ground heat flux declined throughout the growing season and ranged between 3 and 17% of net radiation. Total evapotranspiration was 246, 224 and 283 mm for 2003, 2004 and 2005, respectively. A total derivative analysis of the Penman‐Monteith equation reveals the influence of available energy, vapour pressure deficit and surface conductance in controlling evapotranspiration. Copyright © 2008 John Wiley & Sons, Ltd.