bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Liouville theorems for linear second order degenerate elliptic equations in divergence form
Authors: Moschini Luisa 
Published: August 2004

In this paper we give conditions on the positive function

\varphi ^{2}

under which every bounded solution

σ

of the elliptic equation

\mathrm{∇} \cdot (\varphi ^{2}\mathrm{∇}\sigma ) = 0\text{ in }\mathbb{R}^{n}

must be constant. The case when

\varphi ^{2}

only depends on one or two variables is discussed at length. Moreover the asymptotic behavior of possibly unbounded solutions is characterized, improving in such a way a Liouville theorem due to Berestycki, Caffarelli and Nirenberg.

Résumé

Dans ce papier nous donnons des conditions sur la fonction positive

\varphi ^{2}

sous lesquelles toute solution de l'équation elliptique

\mathrm{∇} \cdot (\varphi ^{2}\mathrm{∇}\sigma ) = 0\text{ en }\mathbb{R}^{n}

doit être constante. Le cas où

\varphi ^{2}

ne dépend que d'une ou deux variables est analysé en détail. Ensuite, le comportement asymptotique des solutions, éventuellement non bornées est characterisé, en donnant ainsi une généralisation d'un théorème de Liouville dû à Berestycki, Caffarelli et Nirenberg.
Super-critical boundary bubbling in a semilinear Neumann problem
Authors: del Pino Manuel , Musso Monica , Pistoia Angela 
Published: August 2004

In this paper we consider the following problem

\tag{0.1}
\begin{cases}
−\mathrm{\Delta }u + u = u^{\frac{N + 2}{N−2} + ɛ}\text{} & \text{in}\:\Omega \text{,} \\ u > 0\text{} & \text{in}\:\Omega \text{,} \\ \frac{\partial u}{\partial \nu } = 0\text{} & \text{on}\:\partial \Omega \text{,} \end{cases}

where

Ω

is a smooth bounded domain in

\mathbb{R}^{N}

and

N⩾3

.

We prove the existence of a one-spike solution to (0.1) which concentrates around a topologically non trivial critical point of the mean curvature of the boundary with positive value. Under some symmetry assumption on

Ω

, namely if

Ω

is even with respect to

N−1

variables and

0 \in \partial \Omega

is a point with positive mean curvature, we prove existence of solutions to (0.1) which resemble the form of a super-position of spikes centered at 0.

Résumé
Dans cet article nous considérons le problème suivant :

\tag{0.2}
\begin{cases} −\mathrm{\Delta }u + u = u^{\frac{N + 2}{N−2} + ɛ}\text{} & \text{dans}\:\Omega \text{,} \\ u > 0\text{} & \text{dans}\:\Omega \text{,} \\ \frac{\partial u}{\partial \nu } = 0\text{} & \text{sur}\:\partial \Omega \text{,}
\end{cases}

oú

Ω

est un domaine borné régulier dans

\mathbb{R}^{N}

et

N⩾3

. Nous prouvons l'existence d'une solution 1-transitoire au problème (0.2), qui se concentre autour d'un point critique topologiquement non trivial de la courbure moyenne, où celle-ci est strictement positive. Sous certaines hypothéses de symétrie sur

Ω

nous prouvons l'existence de solutions de (0.2) qui ressemblent à une superposition des transitoires centrées en un certain point du bord.
VOZ; Isolation and Characterization of Novel Vascular Plant Transcription Factors with a One-Zinc Finger from Arabidopsis thaliana
Authors: Mitsuda Nobutaka , Hisabori Toru , Takeyasu Kunio , Sato Masa H. 
Published: August 2004

AbstractA 38-bp pollen-specific cis-acting region of the AVP1 gene is involved in the expression of the Arabidopsis thaliana V-PPase during pollen development. Here, we report the isolation and structural characterization of AtVOZ1 and AtVOZ2, novel transcription factors that bind to the 38-bp cis-acting region of A. thaliana V-PPase gene, AVP1. AtVOZ1 and AtVOZ2 show 53% amino acid sequence similarity. Homologs of AtVOZ1 and AtVOZ2 are found in various vascular plants as well as a moss, Physcomitrella patens. Promoter-β-glucuronidase reporter analysis shows that AtVOZ1 is specifically expressed in the phloem tissue and AtVOZ2 is strongly expressed in the root. In vivo transient effector-reporter analysis in A. thaliana suspension-cultured cells demonstrates that AtVOZ1 and AtVOZ2 function as transcriptional activators in the Arabidopsis cell. Two conserved regions termed Domain-A and Domain-B were identified from an alignment of AtVOZ proteins and their homologs of O. sativa and P. patens. AtVOZ2 binds as a dimer to the specific palindromic sequence, GCGTNx7ACGC, with Domain-B, which is comprised of a functional novel zinc coordinating motif and a conserved basic region. Domain-B is shown to function as both the DNA-binding and the dimerization domains of AtVOZ2. From highly the conservative nature among all identified VOZ proteins, we conclude that Domain-B is responsible for the DNA binding and dimerization of all VOZ-family proteins and designate it as the VOZ-domain.
Genome-Wide Analysis of Arabidopsis Pentatricopeptide Repeat Proteins Reveals Their Essential Role in Organelle Biogenesis[W]
Authors: Lurin Claire , Andreés Charles , Aubourg Seébastien , Bellaoui Mohammed , Bitton Freédeérique , Bruyère Cleémence , Caboche Michel , Debast Ceédrig , Gualberto Joseé , Hoffmann Beate , Lecharny Alain , Le Ret Monique , Martin-Magniette Marie-Laure , Mireau Hakim , Peeters Nemo , Renou Jean-Pierre , Szurek Boris , Taconnat Ludivine , Small Ian 
Published: August 2004

AbstractThe complete sequence of the Arabidopsis thaliana genome revealed thousands of previously unsuspected genes, many of which cannot be ascribed even putative functions. One of the largest and most enigmatic gene families discovered in this way is characterized by tandem arrays of pentatricopeptide repeats (PPRs). We describe a detailed bioinformatic analysis of 441 members of the Arabidopsis PPR family plus genomic and genetic data on the expression (microarray data), localization (green fluorescent protein and red fluorescent protein fusions), and general function (insertion mutants and RNA binding assays) of many family members. The basic picture that arises from these studies is that PPR proteins play constitutive, often essential roles in mitochondria and chloroplasts, probably via binding to organellar transcripts. These results confirm, but massively extend, the very sparse observations previously obtained from detailed characterization of individual mutants in other organisms.
Novel and Stress-Regulated MicroRNAs and Other Small RNAs from Arabidopsis[W]
Authors: Sunkar Ramanjulu , Zhu Jian-Kang 
Published: August 2004

AbstractMicroRNAs (miRNAs) and short interfering RNAs (siRNAs) are small noncoding RNAs that have recently emerged as important regulators of mRNA degradation, translational repression, and chromatin modification. In Arabidopsis thaliana, 43 miRNAs comprising 15 families have been reported thus far. In an attempt to identify novel and abiotic stress regulated miRNAs and siRNAs, we constructed a library of small RNAs from Arabidopsis seedlings exposed to dehydration, salinity, or cold stress or to the plant stress hormone abscisic acid. Sequencing of the library and subsequent analysis revealed 26 new miRNAs from 34 loci, forming 15 new families. Two of the new miRNAs from three loci are members of previously reported miR171 and miR319 families. Some of the miRNAs are preferentially expressed in specific tissues, and several are either upregulated or downregulated by abiotic stresses. Ten of the miRNAs are highly conserved in other plant species. Fifty-one potential targets with diverse function were predicted for the newly identified miRNAs based on sequence complementarity. In addition to miRNAs, we identified 102 other novel endogenous small RNAs in Arabidopsis. These findings suggest that a large number of miRNAs and other small regulatory RNAs are encoded by the Arabidopsis genome and that some of them may play important roles in plant responses to environmental stresses as well as in development and genome maintenance.
Functional Specialization amongst the Arabidopsis Toc159 Family of Chloroplast Protein Import Receptors[W]
Authors: Kubis Sybille , Patel Ramesh , Combe Jonathan , Beédard Jocelyn , Kovacheva Sabina , Lilley Kathryn , Biehl Alexander , Leister Dario , Riéos Gabino , Koncz Csaba , Jarvis Paul 
Published: August 2004

AbstractThe initial stages of preprotein import into chloroplasts are mediated by the receptor GTPase Toc159. In Arabidopsis thaliana, Toc159 is encoded by a small gene family: atTOC159, atTOC132, atTOC120, and atTOC90. Phylogenetic analysis suggested that at least two distinct Toc159 subtypes, characterized by atToc159 and atToc132/atToc120, exist in plants. atTOC159 was strongly expressed in young, photosynthetic tissues, whereas atTOC132 and atTOC120 were expressed at a uniformly low level and so were relatively prominent in nonphotosynthetic tissues. Based on the albino phenotype of its knockout mutant, atToc159 was previously proposed to be a receptor with specificity for photosynthetic preproteins. To elucidate the roles of the other isoforms, we characterized Arabidopsis knockout mutants for each one. None of the single mutants had strong visible phenotypes, but toc132 toc120 double homozygotes appeared similar to toc159, indicating redundancy between atToc132 and atToc120. Transgenic complementation studies confirmed this redundancy but revealed little functional overlap between atToc132/atToc120 and atToc159 or atToc90. Unlike toc159, toc132 toc120 caused structural abnormalities in root plastids. Furthermore, when proteomics and transcriptomics were used to compare toc132 with ppi1 (a receptor mutant that is specifically defective in the expression, import, and accumulation of photosynthetic proteins), major differences were observed, suggesting that atToc132 (and atToc120) has specificity for nonphotosynthetic proteins. When both atToc159 and the major isoform of the other subtype, atToc132, were absent, an embryo-lethal phenotype resulted, demonstrating the essential role of Toc159 in the import mechanism.
Homologs of Plant PsbP and PsbQ Proteins Are Necessary for Regulation of Photosystem II Activity in the CyanobacteriumSynechocystis6803[W]
Authors: Thornton Leeann E. , Ohkawa Hiroshi , Roose Johnna L. , Kashino Yasuhiro , Keren Nir , Pakrasi Himadri B. 
Published: August 2004

AbstractThe mechanism of oxygen evolution by photosystem II (PSII) has remained highly conserved during the course of evolution from ancestral cyanobacteria to green plants. A cluster of manganese, calcium, and chloride ions, whose binding environment is optimized by PSII extrinsic proteins, catalyzes this water-splitting reaction. The accepted view is that in plants and green algae, the three extrinsic proteins are PsbO, PsbP, and PsbQ, whereas in cyanobacteria, they are PsbO, PsbV, and PsbU. Our previous proteomic analysis established the presence of a PsbQ homolog in the cyanobacterium Synechocystis 6803. The current study additionally demonstrates the presence of a PsbP homolog in cyanobacterial PSII. Both psbP and psbQ inactivation mutants exhibited reduced photoautotrophic growth as well as decreased water oxidation activity under CaCl2-depleted conditions. Moreover, purified PSII complexes from each mutant had significantly reduced activity. In cyanobacteria, one PsbQ is present per PSII complex, whereas PsbP is significantly substoichiometric. These findings indicate that both PsbP and PsbQ proteins are regulators that are necessary for the biogenesis of optimally active PSII in Synechocystis 6803. The new picture emerging from these data is that five extrinsic PSII proteins, PsbO, PsbP, PsbQ, PsbU, and PsbV, are present in cyanobacteria, two of which, PsbU and PsbV, have been lost during the evolution of green plants.
The Oxylipin Signal Jasmonic Acid Is Activated by an Enzyme That Conjugates It to Isoleucine in Arabidopsis[W]
Authors: Staswick Paul E. , Tiryaki Iskender 
Published: August 2004

AbstractDespite its importance in a variety of plant defense responses, our understanding of how jasmonic acid (JA) functions at the biochemical level is limited. Several amino acid conjugates of JA were tested for their ability to complement the JA-insensitive Arabidopsis thaliana mutant jar1-1. Unlike free JA, JA-Ile inhibited root growth in jar1-1 to the same extent as in the wild type, whereas JA-Val, JA-Leu, and JA-Phe were ineffective inhibitors in both genotypes. Thin-layer chromatography and gas chromatography–mass spectrometry (GC-MS) analysis of products produced in vitro by recombinant JAR1 demonstrated that this enzyme forms JA-amido conjugates with several amino acids, including JA-Ile. JA-Val, -Leu, -Ile, and -Phe were each quantified in Arabidopsis seedlings by GC-MS. JA-Ile was found at 29.6 pmole g−1 fresh weight (FW) in the wild type but was more than sevenfold lower in two jar1 alleles. JA-Leu, -Val, and -Phe were present at only low levels in both genotypes. Expression of wild-type JAR1 in transgenic jar1-1 plants restored sensitivity to JA and elevated JA-Ile to the same level as in the wild type. The ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) conjugated to JA was also found in plant tissue at 18.4 pmole g−1 FW. JA-ACC was determined not be an effective jasmonate root inhibitor, and surprisingly, was twofold higher in the mutants than in the wild type. This suggests that another JA-conjugating enzyme(s) is present in Arabidopsis. Synthesis of JA-ACC might provide a mechanism to coregulate the availability of JA and ACC for conversion to the active hormones JA-Ile and ethylene, respectively. We conclude that JAR1 is a JA-amino synthetase that is required to activate JA for optimal signaling in Arabidopsis. Plant hormone activation by conjugation to amino acids and the enzymes involved in their formation were previously unknown.
Morphology of the long and short uveal nerves in the human eye
Authors: May Chr. Albrecht 
Published: August 2004

AbstractThe aim of this study was to examine the architecture of the uveal nerves in the sclera and suprachoroid of human eyes. Eyes from 17 adult human donors were investigated. The uveal nerves in different regions (retrobulbar, intrascleral, suprachoroidal, pars plana) were prepared and studied by light and electron microscopy. In addition, immunohistochemistry was performed for various neuronal markers. The long uveal nerves showed a characteristic suprachoroidal location with no branches supplying the choroid. It was found that typically they are composed of myelinated (75%) and non‐myelinated (25%) nerve fibres. They mainly contain aminergic and sensory nerve fibres. A separate set of cholinergic non‐myelinated nerve fibre bundles runs parallel with these long uveal nerves. The short uveal nerves supply the suprachoroidal nerve plexus with approximately 13% of their nerve fibres. The nerves and the branches supplying the choroid appear as mixed nerves containing sympathetic, parasympathetic and sensory axons. This study therefore provides new information about the quantity, type and distribution of myelinated and non‐myelinated nerve fibres in the posterior uvea of the human eye.
Does the degree of laminarity correlate with site‐specific differences in collagen fibre orientation in primary bone? An evaluation in the turkey ulna diaphysis
Authors: Skedros John G. , Hunt Kenneth J. 
Published: August 2004

Abstractde Margerie hypothesized that preferred orientations of primary vascular canals in avian primary cortical bone mediate important mechanical adaptations. Specifically, bones that receive habitual compression, tension or bending stresses typically have cortices with a low laminarity index (LI) (i.e. relatively lower cross‐sectional areas of circularly (C) orientated primary vascular canals, and relatively higher areas of canals with radial (R), oblique (O) or longitudinal (L) orientations. By contrast, bones subject to habitual torsion have a high LI (i.e. relatively higher C‐orientated canal area) [LI, based on percentage vascular canal area, = C/(C + R + O + L)]. Regional variations in predominant collagen fibre orientation (CFO) may be the adaptive characteristic mediated by LI. Using turkey ulnae, we tested the hypothesis that site‐specific variations in predominant CFO and LI are strongly correlated. Mid‐diaphyseal cross‐sections (100 ± 5 µm) from subadult and adult bones were evaluated for CFO and LI using circularly polarized light images of cortical octants. Results showing significant differences between mean LI of subadult (40.0% ± 10.7%) and adult (50.9% ± 10.4%) (P < 0.01) bones suggest that adult bones experience more prevalent/predominant torsion. Alternatively, this relationship may reflect differences in growth rates. High positive correlations between LI and predominant CFO (subadults: r = 0.735; adults: r = 0.866; P < 0.001) suggest that primary bone can exhibit potentially adaptive material variations that are independent of secondary osteon formation.
Expression of amyloid precursor protein‐like molecule in astroglial cells of the subventricular zone and rostral migratory stream of the adult rat forebrain
Authors: Yasuoka Katsunori , Hirata Kazuho , Kuraoka Akio , He Jian‐wen , Kawabuchi Masaru 
Published: August 2004

AbstractIn adult mammals, new neurons in the subventricular zone (SVZ) of the lateral ventricle (LV) migrate tangentially through the rostral migratory stream (RMS) to the olfactory bulb (OB), where they mature into local interneurons. Using a monoclonal antibody for the β‐amyloid precursor protein (APP) (mAb 22C11), which is specific for the amino‐terminal region of the secreted form of APP and recognizes all APP isoforms and APP‐related proteins, immunoreactivity was detected in specific subpopulations of cells in the SVZ and RMS of the adult rat forebrain. In the SVZ, APP‐like immunoreactivity was detected in the ependymal cells lining the LV and some of the subependymal cells. The latter were regarded as astrocytes, because they were positive for the glial markers, S‐100 protein (S‐100) and glial fibrillary acidic protein (GFAP). APP‐like immunoreactive astrocytes exhibited strong labelling of the perinuclear cytoplasm and often possessed a long, fine process similar to that found with radial glia. The process extended to an APP‐like immunoreactive meshwork in the RMS that consisted of cytoplasmic processes of astrocytes forming ‘glial tubes’. Double‐immunofluorescent labelling with a highly polysialylated neural cell adhesion molecule (PSA‐NCAM) confirmed that the APP‐like immunoreactive astrocytes in the SVZ and meshwork in the RMS made close contact with PSA‐NCAM‐immunopositive neuroblasts, suggesting an interaction between APP‐containing cells and neuroblasts. This region of the adult brain is a useful in vivo model to investigate the role of APP in neurogenesis.
Human leukaemic stem cells: a novel target of therapy
Authors: Sperr W. R. , Hauswirth A. W. , Florian S. , Öhler L. , Geissler K. , Valent P. 
Published: August 2004

AbstractAcute myeloid leukaemia (AML) is a life‐threatening haematopoietic disease that is characterized by clonal growth and the accumulation of myelopoietic progenitor cells. Although AML cells only have a limited potential to undergo differentiation and maturation, each AML clone is organized in a hierarchical manner similar to normal haematopoiesis. Recent data have shown that each AML clone consists of leukaemic stem cells and their progeny, and that AML stem cells differ from more mature cells in several aspects, including survival and target antigen profiles. Most importantly, AML stem cells, but not their progeny, have the capacity to repopulate haematopoietic tissues with leukaemias in NOD/SCID mice. Furthermore, AML stem cells are thought to be responsible for the infinite growth of leukaemias in patients with AML. The phenotypic properties of AML stem cells have also been described. In most cases, these cells are detectable within the CD34+, CD38–, Lin–, CD123+ subpopulation of AML cells. Because of their AML‐initiating and ‐renewing capacity and their unique phenotype, which includes several molecular targets of drug therapy, AML stem cells have recently been proposed as novel important target cell populations in the context of curative therapies. The present article gives an overview of our knowledge about AML stem cells, their phenotype, and their role as a ‘therapy‐target’ in new concepts to treat and to cure patients with AML.
On the way to targeted therapy of mast cell neoplasms: identification of molecular targets in neoplastic mast cells and evaluation of arising treatment concepts
Authors: Valent P. , Ghannadan M. , Akin C. , Krauth M.‐T. , Selzer E. , Mayerhofer M. , Sperr W. R. , Arock M. , Samorapoompichit P. , Horny H.‐P. , Metcalfe D. D. 
Published: August 2004

AbstractSeveral emerging treatment concepts for myeloid neoplasms are based on novel drugs targeting cell surface antigens, signalling pathways, or critical effector molecules. Systemic mastocytosis is a haematopoietic neoplasm that behaves as an indolent myeloproliferative disease in most patients, but can also present as aggressive disease or even as an acute leukaemia. In patients with aggressive disease or mast cell leukaemia, the response to conventional therapy is poor in most cases, and the prognosis is grave. Therefore, a number of attempts have been made to define novel treatment strategies for these patients. One promising approach may be to identify novel targets and to develop targeted drug therapies. In this article, we support the notion that neoplastic mast cells indeed express a number of potential molecular targets including immunoreactive CD antigens, the microphthalmia transcription factor (MITF), and members of the Bcl‐2 family. In addition, the tyrosine kinase receptor KIT and downstream signalling pathways have been proposed as targets of a specific pharmacological intervention. A particular challenge is the disease‐related D816V‐mutated variant of KIT, which is resistant against diverse tyrosine kinase inhibitors including STI571, but may be sensitive to more recently developed targeted compounds. The therapeutic potential of target‐specific approaches in malignant mast cell disorders should be evaluated in forthcoming clinical trials in the near future.
Determinants of the Timing of Interim and Majority of Audit Work
Authors: Makkawi Bilal , Abdolmohammadi Mohammad J. 
Published: August 2004

This study investigates the effect of the risk of material misstatement at the financial statement level on audit program planning. Using an inventory‐production cycle case study, we engaged forty‐eight auditors to assess the risk of material misstatement at the financial statement level. The auditors incorporated their assessments in planning the total number of audit hours and the timing of performance of interim tests and the majority of audit work. To further investigate the sources of variation, we classified auditors by their level of audit experience and tolerance‐for‐ambiguity, and analyzed the effects of these variables on the audit program planning.The results indicate that the risk of material misstatement is statistically significant in explaining changes in the total number of audit hours and the timing of the majority of audit work. Moreover, experience and tolerance‐for‐ambiguity were significant in explaining changes in the timing of interim tests and majority of work. Interaction between experience and tolerance‐for‐ambiguity was also significant in explaining the variation in the total number of hours planned for the overall audit work. This result indicated that inexperienced auditors with a low tolerance‐for‐ambiguity planned more audit procedures than the more experienced auditors with a high tolerance‐for‐ambiguity. Implications for audit practice and research are discussed.