bluuebunny/crossref_metadata_2025_split huggingface dataset:
PlantN-Glycan Processing Enzymes Employ Different Targeting Mechanisms for Their Spatial Arrangement along the Secretory Pathway
Authors: Saint-Jore-Dupas Claude , Nebenführ Andreas , Boulaflous Aurélia , Follet-Gueye Marie-Laure , Plasson Carole , Hawes Chris , Driouich Azeddine , Faye Loïc , Gomord Véronique 
Published: December 2006

AbstractThe processing of N-linked oligosaccharides in the secretory pathway requires the sequential action of a number of glycosidases and glycosyltransferases. We studied the spatial distribution of several type II membrane-bound enzymes from Glycine max, Arabidopsis thaliana, and Nicotiana tabacum. Glucosidase I (GCSI) localized to the endoplasmic reticulum (ER), α-1,2 mannosidase I (ManI) and N-acetylglucosaminyltransferase I (GNTI) both targeted to the ER and Golgi, and β-1,2 xylosyltransferase localized exclusively to Golgi stacks, corresponding to the order of expected function. ManI deletion constructs revealed that the ManI transmembrane domain (TMD) contains all necessary targeting information. Likewise, GNTI truncations showed that this could apply to other type II enzymes. A green fluorescent protein chimera with ManI TMD, lengthened by duplicating its last seven amino acids, localized exclusively to the Golgi and colocalized with a trans-Golgi marker (ST52-mRFP), suggesting roles for protein–lipid interactions in ManI targeting. However, the TMD lengths of other plant glycosylation enzymes indicate that this mechanism cannot apply to all enzymes in the pathway. In fact, removal of the first 11 amino acids of the GCSI cytoplasmic tail resulted in relocalization from the ER to the Golgi, suggesting a targeting mechanism relying on protein–protein interactions. We conclude that the localization of N-glycan processing enzymes corresponds to an assembly line in the early secretory pathway and depends on both TMD length and signals in the cytoplasmic tail.
Two Cytosolic Glutamine Synthetase Isoforms of Maize Are Specifically Involved in the Control of Grain Production
Authors: Martin Antoine , Lee Judy , Kichey Thomas , Gerentes Denise , Zivy Michel , Tatout Christophe , Dubois Frédéric , Balliau Thierry , Valot Benoît , Davanture Marlène , Tercé-Laforgue Thérèse , Quilleré Isabelle , Coque Marie , Gallais André , Gonzalez-Moro María-Begoña , Bethencourt Linda , Habash Dimah Z. , Lea Peter J. , Charcosset Alain , Perez Pascual , Murigneux Alain , Sakakibara Hitoshi , Edwards Keith J. , Hirel Bertrand 
Published: December 2006

Abstract
The roles of two cytosolic maize glutamine synthetase isoenzymes (GS1), products of the Gln1-3 and Gln1-4 genes, were investigated by examining the impact of knockout mutations on kernel yield. In the gln1-3 and gln1-4 single mutants and the gln1-3 gln1-4 double mutant, GS mRNA expression was impaired, resulting in reduced GS1 protein and activity. The gln1-4 phenotype displayed reduced kernel size and gln1-3 reduced kernel number, with both phenotypes displayed in gln1-3 gln1-4. However, at maturity, shoot biomass production was not modified in either the single mutants or double mutants, suggesting a specific impact on grain production in both mutants. Asn increased in the leaves of the mutants during grain filling, indicating that it probably accumulates to circumvent ammonium buildup resulting from lower GS1 activity. Phloem sap analysis revealed that unlike Gln, Asn is not efficiently transported to developing kernels, apparently causing reduced kernel production. When Gln1-3 was overexpressed constitutively in leaves, kernel number increased by 30%, providing further evidence that GS1-3 plays a major role in kernel yield. Cytoimmunochemistry and in situ hybridization revealed that GS1-3 is present in mesophyll cells, whereas GS1-4 is specifically localized in the bundle sheath cells. The two GS1 isoenzymes play nonredundant roles with respect to their tissue-specific localization.
CONSTANS and the CCAAT Box Binding Complex Share a Functionally Important Domain and Interact to Regulate Flowering ofArabidopsis
Authors: Wenkel Stephan , Turck Franziska , Singer Kamy , Gissot Lionel , Le Gourrierec José , Samach Alon , Coupland George 
Published: December 2006

AbstractThe CCT (for CONSTANS, CONSTANS-LIKE, TOC1) domain is found in 45 Arabidopsis thaliana proteins involved in processes such as photoperiodic flowering, light signaling, and regulation of circadian rhythms. We show that this domain exhibits similarities to yeast HEME ACTIVATOR PROTEIN2 (HAP2), which is a subunit of the HAP2/HAP3/HAP5 trimeric complex that binds to CCAAT boxes in eukaryotic promoters. Moreover, we demonstrate that CONSTANS (CO), which promotes Arabidopsis flowering, interacts with At HAP3 and At HAP5 in yeast, in vitro, and in planta. Mutations in CO that delay flowering affect residues highly conserved between CCT and the DNA binding domain of HAP2. Taken together, these data suggest that CO might replace At HAP2 in the HAP complex to form a trimeric CO/At HAP3/At HAP5 complex. Flowering was delayed by overexpression of At HAP2 or At HAP3 throughout the plant or in phloem companion cells, where CO is expressed. This phenotype was correlated with reduced abundance of FLOWERING LOCUS T (FT) mRNA and no change in CO mRNA levels. At HAP2 or At HAP3 overexpression may therefore impair formation of a CO/At HAP3/At HAP5 complex leading to reduced expression of FT. During plant evolution, the number of genes encoding HAP proteins was greatly amplified, and these proteins may have acquired novel functions, such as mediating the effect of CCT domain proteins on gene expression.
A Ferroxidation/Permeation Iron Uptake System Is Required for Virulence inUstilago maydis
Authors: Eichhorn Heiko , Lessing Franziska , Winterberg Britta , Schirawski Jan , Kämper Jörg , Müller Philip , Kahmann Regine 
Published: December 2006

AbstractIn the smut fungus Ustilago maydis, a tightly regulated cAMP signaling cascade is necessary for pathogenic development. Transcriptome analysis using whole genome microarrays set up to identify putative target genes of the protein kinase A catalytic subunit Adr1 revealed nine genes with putative functions in two high-affinity iron uptake systems. These genes locate to three gene clusters on different chromosomes and include the previously identified complementing siderophore auxotroph genes sid1 and sid2 involved in siderophore biosynthesis. Transcription of all nine genes plus three additional genes associated with the gene clusters was also coregulated by iron through the Urbs1 transcription factor. Two components of a high-affinity iron uptake system were characterized in more detail: fer2, encoding a high-affinity iron permease; and fer1, encoding an iron multicopper oxidase. Fer2 localized to the plasma membrane and complemented an ftr1 mutant of Saccharomyces cerevisiae lacking a high-affinity iron permease. During pathogenic development, fer2 expression was confined to the phase of hyphal proliferation inside the plant. fer2 as well as fer1 deletion mutants were strongly affected in virulence. These data highlight the importance of the high-affinity iron uptake system via an iron permease and a multicopper oxidase for biotrophic development in the U. maydis/maize (Zea mays) pathosystem.
SUPPRESSOR OF FRIGIDA4, Encoding a C2H2-Type Zinc Finger Protein, Represses Flowering by Transcriptional Activation ofArabidopsis FLOWERING LOCUS C
Authors: Kim Sanghee , Choi Kyuha , Park Chulmin , Hwang Hyun-Ju , Lee Ilha 
Published: December 2006

AbstractFLOWERING LOCUS C (FLC), a strong floral repressor, is one of the central regulators of flowering in Arabidopsis thaliana. The expression of FLC is increased by FRIGIDA (FRI) but decreased by vernalization, a long period of cold exposure that accelerates flowering. Although many aspects of FLC regulation have been reported, it is not known how FLC is transcriptionally activated by FRI at the molecular level. We isolated suppressor of FRIGIDA4 (suf4), a mutant that flowers early as a result of low FLC expression. SUF4 encodes a nuclear-localized protein with two C2H2-type zinc finger motifs and a Pro-rich domain. SUF4 protein interacts with FRI and FRIGIDA-LIKE1 (FRL1), two genes for which single mutations have the same phenotype as suf4. SUF4 also bound to the promoter of FLC in a chromatin immunoprecipitation assay, suggesting that SUF4 acts as a transcriptional activator of FLC after forming a complex with FRI and FRL1. In addition, suf4 suppresses luminidependens (ld), a late-flowering mutation that causes an increase of FLC, and SUF4 protein directly interacts with LD. Thus, we propose that LD binds to SUF4 to suppress its activity in the absence of FRI.
Edgeworth and Lindahl–Foley equilibria of a General Equilibrium Model with Private Provision of Pure Public Goods
Authors: FLORENZANO MONIQUE , Del MERCATO ELENA L. 
Published: December 2006

AbstractIn this paper, we propose a definition of Edgeworth equilibrium for a private ownership production economy with (possibly infinitely) many private goods and a finite number of pure public goods. We show that Edgeworth equilibria exist whatever be the dimension of the private goods space and can be decentralized, in the finite and infinite dimensional cases, as Lindahl–Foley equilibria. Existence theorems for Lindahl–Foley equilibria are a by‐product of our results.
Fixed Wages and Bonuses in Agency Contracts: The Case of a Continuous State Space
Authors: RACIONERO MARIA , QUIGGIN JOHN 
Published: December 2006

AbstractIn this paper, we extend the state‐contingent production approach to principal–agent problems to the case where the state space is an atomless continuum. The approach is modelled on the treatment of optimal tax problems. The central observation is that, under reasonable conditions, the optimal contract may involve a fixed wage with a bonus for above‐normal performance. This is analogous to the phenomenon of “bunching” at the bottom in the optimal tax literature.
Political Uncertainty and Policy Innovation
Authors: KOTSOGIANNIS CHRISTOS , SCHWAGER ROBERT 
Published: December 2006

AbstractConventional wisdom has it that outside sources of information enhance the capability of political institutions to separate selfish from benevolent incumbents. This paper investigates, in the presence of innovative public policies whose outcomes are uncertain, the role of outside information and shows that it is more involved than typically thought. While it is true that enhanced information helps in separating politicians, it also creates an externality that reduces the incentives to experiment with innovative public policies.
Redistributive Taxation and Public Education
Authors: KRAUSE ALAN 
Published: December 2006

AbstractThis paper examines the relative effectiveness of publicly provided ‘white collar’ professional (university) education versus ‘blue collar’ vocational training in achieving the government's redistributive goals. Although professional education directly benefits high‐skill high‐income workers and vocational training directly benefits low‐skill low‐income workers, we show that either provision of more professional education or less vocational training than in the first‐best allocation is optimal along the second‐best Paretian frontier since this facilitates incentive compatibility in labor supply decisions. Accordingly, the observation that public higher education expenditures in most countries favor universities is not necessarily inconsistent with an optimal redistributive program.
Business Cycles, Heuristic Expectation Formation, and Contracyclical Policies
Authors: WESTERHOFF FRANK H. 
Published: December 2006

AbstractWe develop a simple Keynesian‐type business cycle model in which agents use simple heuristics to predict national income. To be precise, the agents either form (destabilizing) extrapolative expectations or (stabilizing) regressive expectations, a decision which depends on the rules forecasting performance in the recent past. As it turns out, an unending evolutionary competition between the rules may generate endogenous complex business cycles. We also explore the effectiveness of some common governmental intervention strategies. Our model suggests that policy makers may be able to stabilize output fluctuations, yet due to system immanent nonlinearities this may prove to be quite difficult.
Bureaucracy, Tax System, and Economic Performance
Authors: OTT INGRID 
Published: December 2006

AbstractThis paper investigates the consequences for government size, growth and welfare if a selfish bureaucracy provides a congested input. Alternative exogenous tax systems are introduced and numerical analyses are carried out. The welfare optimum is only met under very specific assumptions: proportional congestion, a tax system only consisting of distortionary taxes and a bureaucracy that maximizes the budget's growth rate. Otherwise the relative size of the public sector becomes suboptimally large thus inducing welfare losses. From a welfare economic point of view bureaucratic selfishness is worse than a suboptimal taxing regime that does not (completely) internalize the congestion externalities.
Functional biology of plant phosphate uptake at root and mycorrhiza interfaces
Authors: Bucher Marcel 
Published: December 2006

SummaryPhosphorus (P) is an essential plant nutrient and one of the most limiting in natural habitats as well as in agricultural production world‐wide. The control of P acquisition efficiency and its subsequent uptake and translocation in vascular plants is complex. The physiological role of key cellular structures in plant P uptake and underlying molecular mechanisms are discussed in this review, with emphasis on phosphate transport across the cellular membrane at the root and arbuscular–mycorrhizal (AM) interfaces. The tools of molecular genetics have facilitated novel approaches and provided one of the major driving forces in the investigation of the basic transport mechanisms underlying plant P nutrition. Genetic engineering holds the potential to modify the system in a targeted way at the root–soil or AM symbiotic interface. Such approaches should assist in the breeding of crop plants that exhibit improved P acquisition efficiency and thus require lower inputs of P fertilizer for optimal growth. Whether engineering of P transport systems can contribute to enhanced P uptake will be discussed.

Contents

Summary
11

I.
Introduction
11

II.
Phosphate uptake and its regulation
14

III.
Phosphate uptake assisted by the arbuscular—mycorrhizal symbiosis
18

IV.
Agricultural potential
21

V.
Conclusions and perspectives
21

Acknowledgements
22

References
22
CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: The Epidemiology and Outcome of Acute Renal Failure and the Impact on Chronic Kidney Disease
Authors: Block Clay A. , Schoolwerth Anton C. 
Published: December 2006

AbstractAcute renal failure (ARF) is a common condition, especially among the critically ill, and confers a high mortality. Recent publications have highlighted changes in the epidemiology and improvement in mortality that was long thought to be static despite improvements in clinical care. The incidence of ARF is increasing. Efforts, such as the Acute Dialysis Quality Initiative, are being undertaken to establish a consensus definition of ARF, and to distinguish between varying degrees of acute kidney injury. Data are emerging to allow comparison of the epidemiology of ARF across institutions internationally. There is ongoing recognition of the important interaction between ARF and chronic kidney disease. Two brief case reports are offered to help frame the context and clinical impact of this disorder, followed by a review of some of the recent literature that addresses these points.
CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: Low‐dose Dopamine in the Intensive Care Unit
Authors: Karthik Swaminathan , Lisbon Alan 
Published: December 2006

AbstractFor much of the last four decades, low‐dose dopamine has been considered the drug of choice to treat and prevent renal failure in the intensive care unit (ICU). The multifactorial etiology of renal failure in the ICU and the presence of coexisting multisystem organ dysfunction make the design and execution of clinical trials to study this problem difficult. However, in the last decade, several meta‐analyses and one large randomized trial have all shown a lack of benefit of low‐dose dopamine in improving renal function. There are multiple reasons for this lack of efficacy. While dopamine does cause a diuretic effect, it does very little to improve mortality, creatinine clearance, or the incidence of dialysis. Evidence is also growing of its adverse effects on the immune, endocrine, and respiratory systems. It may also potentially increase mortality in sepsis. It is the opinion of the authors that the practice of using low‐dose dopamine should be abandoned. Other drugs and treatment modalities need to be explored to address the serious issue of renal failure in the ICU.
CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: Perioperative Fluid Management: Current Consensus and Controversies
Authors: Yeager Mark P. , Spence Brian C. 
Published: December 2006

AbstractThe scientific knowledge base that supports clinical decisions about perioperative fluid management continues to evolve. However, despite these advancements in the understanding of the physiology of fluid replacement, the definition of ‘‘optimal’’ perioperative fluid management remains a matter of clinical judgment. With an appreciation of the many factors, both sensible and insensible, that contribute to changes in blood and extracellular fluid volume during surgery, clinicians have tried to create reproducible and generally applicable formulas for replacement of fluid during surgery. These formulas have been challenged recently by the introduction of new tools for monitoring cardiopulmonary function, by the implementation of monitor‐guided protocols for fluid management, and, more recently, by clinical data suggesting that fluid restriction may improve surgical outcomes in some clinical settings. The relative ease of pre‐identified fluid replacement protocols is being slowly replaced by data‐guided interventions that take into account a variety of factors. Clinicians are therefore required to tailor their fluid replacement strategies based on preoperative patient characteristics, the type of surgery and even the type of anesthetic that is utilized. Some of the benefits of this new approach range from relatively ‘‘minor’’ outcomes such as diminished nausea after surgery to preventing postoperative complications such as wound breakdown and cardiopulmonary failure.
CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: The Pulmonary Artery Catheter in Critical Care
Authors: McGee William T. , Mailloux Patrick , Jodka Paul , Thomas Joss 
Published: December 2006

AbstractPulmonary artery catheterization has been a routine part of care for critically ill patients over the past 25 years. Primary hemodynamic data regarding cardiac output and pulmonary pressures can be utilized to make diagnoses and guide therapy. Tissue oxygen delivery and utilization allow inferences about the efficiency of the cardiopulmonary system and the impact of disease and medical therapies on tissue metabolism. Goals of high level invasive monitoring of cardiopulmonary function with pulmonary artery catheterization are organ salvage and minimizing complications associated with critical illness. Optimizing renal perfusion and minimizing pulmonary congestion with precise volume titration are common reasons for performing pulmonary artery catheterization in the intensive care unit. Despite being reassuring to clinicians that hemodynamic therapy is optimal, multiple data from well conducted clinical studies have not demonstrated outcome benefits to patients related to pulmonary artery catheterization. Less invasive techniques to obtain data regarding hemodynamic function are now entering the clinical arena and are being actively investigated.
CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: Electrolyte Disturbances in the Intensive Care Unit
Authors: Sedlacek Martin , Schoolwerth Anton C. , Remillard Brian D. 
Published: December 2006

AbstractThe development of many electrolyte disturbances in the ICU can be prevented by attention to the use of intravenous fluids and nutrition. Hyponatremia is a relative contraindication to the use of hypotonic intravenous fluids and hypernatremia calls for the administration of water. Formulae have been devised to guide the therapy of severe hyponatremia and hypernatremia. All formulae regard the patient as a closed system, and none takes into account ongoing fluid losses that are highly variable between patients. Thus, therapy of severe hyponatremia and hypernatremia must be closely monitored with serial electrolyte measurements. The significance of hypocalcemia in the critically ill is controversial. Hypokalemia, hypophosphatemia, and hypomagnesemia should be corrected.
CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: Current Diagnosis and Management of Hypertensive Emergency
Authors: Haas Andrew R. , Marik Paul E. 
Published: December 2006

AbstractThe appropriate and timely evaluation and treatment of patients with severely elevated blood pressure is essential to avoid serious adverse outcomes. Most importantly, the distinction between a hypertensive emergency (crisis) and urgency needs to be made. A sudden elevation in systolic (SBP) and/or diastolic blood pressure (DBP) that is associated with acute end organ damage (cardiovascular, cerebrovascular, or renal) is defined as a hypertensive crisis or emergency. In contrast, acute elevation in SBP and/or DBP not associated with evidence of end organ damage is defined as hypertensive urgency. In patients with a hypertensive emergency, blood pressure control should be attained as expeditiously as possible with parenteral medications to prevent ongoing and potentially permanent end organ damage. In contrast, with hypertensive urgency, blood pressure control can be achieved with the use of oral medications within 24–48 hours. This paper reviews the management of hypertensive emergencies.
CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: Anemia and Red Blood Cell Transfusion in the Critically Ill
Authors: Corwin Howard L. 
Published: December 2006

AbstractCritically ill patients are anemic early in their intensive care unit (ICU) course. As a consequence of this anemia they receive a large number of red blood cell (RBC) transfusions. There is little evidence that “routine” transfusion of stored allogeneic RBCs is beneficial to critically ill patients and may in fact be associated with worse clinical outcomes. It is clear that most critically ill patients can tolerate hemoglobin levels as low as 7 g/dl and therefore a more conservative approach to RBC transfusion is warranted. Strategies to minimize loss of blood and increase the production of RBCs are also important in the management of all critically ill patients.