bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mutation of l7Rn3 Shows That Odz4 Is Required for Mouse Gastrulation
Authors: Lossie Amy C , Nakamura Hisashi , Thomas Sharon E , Justice Monica J 
Published: October 2004

Abstract
A mouse homolog of the Drosophila pair-rule gene Odd Oz (Odz4) maps to the critical region of the l7Rn3 locus on mouse chromosome 7. Here we show that Odz4 is an excellent candidate for this allelic series because (1) it spans the entire critical region, (2) the phenotypes correlate with embryonic expression, (3) the complex genetic inheritance of the alleles is consistent with complex transcriptional regulation, and (4) one allele has a mutation in a conserved amino acid. Odz4 uses five alternate promoters that encode both secreted and membrane-bound proteins. Intragenic complementation of the l7Rn3 alleles is consistent with these multiple-protein isoforms. Further, the allelic series shows that Odz4 is required to establish the anterior-posterior axis of the gastrulating mouse embryo and is necessary later for mesoderm-derived tissues such as somites, heart, and skeleton. Sequencing of RT-PCR products from five of the six alleles reveals a nonconservative amino acid change in the l7Rn3m4 allele. This amino acid is important evolutionarily, as it is conserved to Drosophila. Together, our data indicate that Odz4 is mutated in the l7Rn3 allele series and performs roles in the mouse brain, heart, and embryonic patterning similar to those of its Drosophila counterpart.
Regulation of Leucine Uptake by tor1+ in Schizosaccharomyces pombe Is Sensitive to Rapamycin
Authors: Weisman Ronit , Roitburg Irina , Nahari Tal , Kupiec Martin 
Published: October 2004

Abstract
TOR protein kinases are key regulators of cell growth in eukaryotes. TOR is also known as the target protein for the immunosuppressive and potentially anticancer drug rapamycin. The fission yeast Schizosaccharomyces pombe has two TOR homologs. tor1+ is required under starvation and a variety of stresses, while tor2+ is an essential gene. Surprisingly, to date no rapamycin-sensitive TOR-dependent function has been identified in S. pombe. Herein, we show that S. pombe auxotrophs, in particular leucine auxotrophs, are sensitive to rapamycin. This sensitivity is suppressed by deletion of the S. pombe FKBP12 or by introducing a rapamycin-binding defective tor1 allele, suggesting that rapamycin inhibits a tor1p-dependent function. Sensitivity of leucine auxotrophs to rapamycin is observed when ammonia is used as the nitrogen source and can be suppressed by its replacement with proline. Consistently, using radioactive labeled leucine, we show that cells treated with rapamycin or disrupted for tor1+ are defective in leucine uptake when the nitrogen source is ammonia but not proline. Recently, it has been reported that tsc1+ and tsc2+, the S. pombe homologs for the mammalian TSC1 and TSC2, are also defective in leucine uptake. TSC1 and TSC2 may antagonize TOR signaling in mammalian cells and Drosophila. We show that reduction of leucine uptake in tor1 mutants is correlated with decreased expression of three putative amino acid permeases that are also downregulated in tsc1 or tsc2. These findings suggest a possible mechanism for regulation of leucine uptake by tor1p and indicate that tor1p, as well as tsc1p and tsc2p, positively regulates leucine uptake in S. pombe.
Long-Term Experimental Evolution in Escherichia coli. XII. DNA Topology as a Key Target of Selection
Authors: Crozat Estelle , Philippe Nadège , Lenski Richard E , Geiselmann Johannes , Schneider Dominique 
Published: October 2004

AbstractThe genetic bases of adaptation are being investigated in 12 populations of Escherichia coli, founded from a common ancestor and serially propagated for 20,000 generations, during which time they achieved substantial fitness gains. Each day, populations alternated between active growth and nutrient exhaustion. DNA supercoiling in bacteria is influenced by nutritional state, and DNA topology helps coordinate the overall pattern of gene expression in response to environmental changes. We therefore examined whether the genetic controls over supercoiling might have changed during the evolution experiment. Parallel changes in topology occurred in most populations, with the level of DNA supercoiling increasing, usually in the first 2000 generations. Two mutations in the topA and fis genes that control supercoiling were discovered in a population that served as the focus for further investigation. Moving the mutations, alone and in combination, into the ancestral background had an additive effect on supercoiling, and together they reproduced the net change in DNA topology observed in this population. Moreover, both mutations were beneficial in competition experiments. Clonal interference involving other beneficial DNA topology mutations was also detected. These findings define a new class of fitness-enhancing mutations and indicate that the control of DNA supercoiling can be a key target of selection in evolving bacterial populations.
Genome-Wide Screen for Genes With Effects on Distinct Iron Uptake Activities in Saccharomyces cerevisiae
Authors: Lesuisse Emmanuel , Knight Simon A B , Courel Maïté , Santos Renata , Camadro Jean-Michel , Dancis Andrew 
Published: October 2004

Abstract
We screened a collection of 4847 haploid knockout strains (EUROSCARF collection) of Saccharomyces cerevisiae for iron uptake from the siderophore ferrioxamine B (FOB). A large number of mutants showed altered uptake activities, and a few turned yellow when grown on agar plates with added FOB, indicating increased intracellular accumulation of undissociated siderophores. A subset consisting of 197 knockouts with altered uptake was examined further for regulated activities that mediate cellular uptake of iron from other siderophores or from iron salts. Hierarchical clustering analysis grouped the data according to iron sources and according to mutant categories. In the first analysis, siderophores grouped together with the exception of enterobactin, which grouped with iron salts, suggesting a reductive pathway of iron uptake for this siderophore. Mutant groupings included three categories: (i) high-FOB uptake, high reductase, low-ferrous transport; (ii) isolated high- or low-FOB transport; and (iii) induction of all activities. Mutants with statistically altered uptake activities included genes encoding proteins with predominant localization in the secretory pathway, nucleus, and mitochondria. Measurements of different iron-uptake activities in the yeast knockout collection make possible distinctions between genes with general effects on iron metabolism and those with pathway-specific effects.
Chromosome Identification and Nomenclature of Sorghum bicolor
Authors: Kim Jeong-Soon , Klein Patricia E , Klein Robert R , Price H James , Mullet John E , Stelly David M 
Published: October 2004

Abstract
Linkage group identities and homologies were determined for metaphase chromosomes of Sorghum bicolor (2n = 20) by FISH of landed BACs. Relative lengths of chromosomes in FISH-karyotyped metaphase spreads of the elite inbred BTx623 were used to estimate the molecular size of each chromosome and to establish a size-based nomenclature for sorghum chromosomes (SBI-01–SBI-10) and linkage groups (LG-01 to LG-10). Lengths of arms were determined to orient linkage groups relative to a standard karyotypic layout (short arms at top). The size-based nomenclature for BTx623 represents a reasonable choice as the standard for a unified chromosome nomenclature for use by the sorghum research community.
Block copolymer of trans‐polyisoprene and urethane segment: Crystallization behavior and morphology
Authors: Sun Xiaohui , Ni Xiuyuan 
Published: October 2004

AbstractA new type of urethane segmented copolymer was prepared from hydroxyl‐terminated trans‐polyisoprene (HTTPI) and toluene diisocyanate (TDI). The structures of the copolymer were characterized by FTIR and GPC. Crystalline properties of trans‐polyisoprene (TPI) segments were investigated using WAXD and DSC techniques. The crystals of TPI segments are inclined to exist in low‐melting form (LM). The melting temperature of TPI shifts to a lower temperature as the urethane segment was introduced. DMA studies show that, when TPI crystals were at the melting state, the storage modulus of the copolymer depended on the content of urethane segment. The hard segment here serves as physical crosslinkage. Nonisothermal crystallization kinetics of TPI segment was studied on the basis of the Ozawa equation. It was found that the hard segment suppresses the crystallization of the TPI segment. Morphology of two‐phase separation was observed in the copolymer by SEM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2286–2294, 2004
Recent developments in computational approaches for uncovering genomic homology
Authors: Simillion Cedric , Vandepoele Klaas , Van de Peer Yves 
Published: October 2004

AbstractIdentifying genomic homology within and between genomes is essential when studying genome evolution. In the past years, different computational techniques have been developed to detect homology even when the actual similarity between homologous segments is low. Depending on the strategy used, these methods search for pairs of chromosomal segments between which either both gene content and order are conserved or gene content only. However, due to fact that, after their divergence, homologous segments can lose a different set of genes, these methods still often fail to detect genomic homology. Recently, more advanced approaches have been developed that can combine gene order and content information of multiple genomic segments. BioEssays 26:1225–1235, 2004. © 2004 Wiley Periodicals, Inc.
The source(s) for new pancreatic beta cells in adult life
Authors: Bock Troels 
Published: October 2004

AbstractThe natural source for new pancreatic beta cells is an important issue both for understanding the pathogenesis of diabetes, and for possibly curing diabetes by increasing the number of beta cells. Dor et al.1 investigated beta‐cell renewal and regeneration by genetic lineage analysis in mice during physiological growth and after partial pancreatectomy. The data conclusively showed that beta‐cell replication was the only source for new beta cells without contributions from stem cells or other non‐beta cells. This underlines the capacity for beta‐cell self‐renewal and casts doubt that other cell types are able to generate new beta cells in the intact pancreas. BioEssays 26:1156–1159, 2004. © 2004 Wiley Periodicals, Inc.
A synthetic peptide reproducing the mitochondrial targeting motif of AKAP121: A conformational study
Authors: De Capua Antonia , Del Gatto Annarita , Zaccaro Laura , Saviano Gabriella , Carlucci Annalisa , Livigni Alessandra , Gedressi Chiara , Tancredi Teodorico , Pedone Carlo , Saviano Michele 
Published: October 2004

AbstractThe conformational features of a peptide derived by the 10–30 sequence of the mitochondrial domain of AKAP121 [Ac‐1XKKPLALPGMLALLGWWWFFSRKKX25‐NH2 (X = β‐Ala)] in water and in a water/triflouroethanol (TFE) mixture at 298 K have been determined by NMR and CD spectroscopy. Backbone clustering analysis of NMR‐derived structures led to the identification of a single representative structure in water/TFE. The structure of the peptide consists mainly of an α‐helix, whose core is the region 7–23, with a less ordered N‐terminal part. These data are confirmed by CD analysis. It is noteworthy that the high hydrophobic Trp16–Phe20 segment, that might also mediate interaction with tubulin, is organized in an α‐helical wheel. Our conformational data can be the starting point for the development of highly selective peptides that interfere with the biological function of the Protein Kinase A scaffold protein AKAP121. © 2004 Wiley Periodicals, Inc. Bioploymers (Pept Sci), 2004
Induction of signaling pathways by herpes simplex virus type 1 through glycoprotein H peptides
Authors: Galdiero Stefania , Vitiello Mariateresa , D'Isanto Marina , Di Niola Erminia , Peluso Lucia , Raieta Katia , Pedone Carlo , Galdiero Massimiliano , Benedetti Ettore 
Published: October 2004

AbstractEukaryotic cells respond to extracellular stimuli, such as viruses, by recruiting signal transduction pathways, many of which are mediated through activation of distinct mitogen‐activated protein kinase (MAPK) cascades and activation of transductional regulation factors. The best characterized of this pathway are the extracellular signal regulated Kinase (ERK), the c‐Jun N‐terminal kinase/stress activated protein kinase (JNK/SAPK), and the p38 MAPK cascade.Herpes simplex virus type 1 (HSV‐1) encodes at least 11 envelope glycoproteins, which alone or in concert play different roles in viral adsorption, entry, cell‐to‐cell spread, and immune evasion. Of these proteins, three are designated glycoprotein B (gB), glycoprotein D (gD), and the gH/gL heterodimer, are clearly involved in attachment and entry, and therefore possible candidates in inducing early cellular activation.Nevertheless, the precise role of each glycoprotein and the cellular factor involved remain elusive. The signal transduction pathways involved, and the outcome of cellular activation on viral entry or postentry events, are still to be elucidated. To better understand the role of signal transduction pathways and phosphorylation events in HSV‐1 entry, synthetic peptides modeled on HSV‐1 gH were synthesized and tested for MEK1‐MEK2/MAPK cascade activation. Our results show a major involvement of the JNK pathway in the intracellular signal transmission after stimulation with gH HSV‐1 peptides. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004
Die Einsamkeit des Amateurs. Hobby‐ und Dandy‐Chemiker in ihren Laboratorien
Authors: Krätz Otto 
Published: October 2004

AbstractDem Hobby‐ und Amateur‐Chemiker [1] kommt in der Literatur in der Regel eine besondere Aufgabe zu: Er bereichert das Repertoire der Literaten mit seltsam‐unheimlichen, aber besiegbaren und daher selten wirklich apokalyptischen Figuren. Die folgende Betrachtung schöpft in einer Anzahl von Beispielen aus der schöngeistigen Literatur, aber auch aus Biographien etc. und ist ausschließlich dem Amateur‐Alchemisten und Amateur‐Chemiker gewidmet. Amateure sind auf sich gestellt. Ihr besonderes Kennzeichen ist die Ferne zu ihrer Umgebung.
Resublimation — die faszinierende Bildung von Raureif
Authors: de Vries Tönjes , Paschmann Antje 
Published: October 2004

AbstractWer kennt sie nicht — diese ganz besondere Atmosphäre an einem kalten sonnigen Wintermorgen, wenn die Welt in einen weißen Schleier aus Raureif gehüllt ist. Sieht man genau hin, so erkennt man, dass es sich dabei um kleine nadelförmige Strukturen aus Eis handelt, die z. B. an Grashalmen und Zweigen haften. Hinter diesem Phänomen verbirgt sich der Vorgang der Resublimation.Im vorliegenden Beitrag werden Untersuchungsergebnisse vorgestellt, die belegen, dass Schüler z. T. große Schwierigkeiten haben, das beschriebene Phänomen angemessen zu erklären. Es werden Experimente vorgestellt, die auf einfache Weise den Vorgang der Resublimation zeigen und eine Erarbeitung des Phänomens erlauben. Gleichzeitig bieten diese Versuche die Möglichkeit, das faszinierende Wachstum fraktaler Eiskristalle gewissermaßen „live”︁ mitzuerleben. In einigen Klassen des 7. Jahrgangs sind diese Experimente bereits im Unterricht erprobt worden.
Plädoyer für den Einsatz der Gaschromatographie im Unterricht
Authors: Wiederholt Erwin , Fahrney Volker 
Published: October 2004

AbstractSelbst in wirtschaftlich angespannten Zeiten lässt sich die Gaschromatographie im Chemieunterricht einsetzen. Trennungen von Gasgemischen werden bei Raumtemperatur mit dem Minimal‐Gaschromatograph als vollwertigem Gaschromatographen ausgeführt. Mit zwei hintereinandergeschalteten Minimal‐Gaschromatographen wird der Nachweis und oft sogar die Identifizierung einzelner Gemischkomponenten möglich oder erleichtert.
MRI‐monitored electromagnetic heating using iterative feedback control and phase interference mapping
Authors: Behnia B. , Webb A.G. 
Published: October 2004

AbstractNoninvasive electromagnetic hyperthermia, used in combination with radiotherapy or chemotherapy, is a promising technique in the treatment of large, deep‐lying tumours. One of the major difficulties in effective implementation, however, is that the spatial distribution of electric fields within the patient is strongly influenced by tissue morphology and dielectric properties, and is therefore difficult to model. Even when desired heating profiles are achieved experimentally, the specific absorption rate at the focus generally does not reach its theoretical maximum value since the E‐fields are not completely coherent. In this article, a new method, phase interference mapping, is developed to address this latter problem and is demonstrated in phantoms. The complete process for optimizing spatial and temporal control of electromagnetic heating has three separate steps. The first involves phase calibration of the individual dipoles of a phased array applicator with a noninvasive E‐field probe placed on the surface of the phantom. In the second step, an iterative feedback method is used to rapidly steer the thermal focus as close as possible to the desired location. Noninvasive mapping of the temperature and specific absorption rate is realized by magnetic resonance imaging. The final step in the process consists of phase interference mapping of the dipoles, to maximize E‐field coherence. Temporal control of the temperature rise or specific absorption rate can then be performed. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 23B: 1–15, 2004
Prenatal development of the rodent rostral migratory stream
Authors: Pencea Viorica , Luskin Marla B. 
Published: October 2004

AbstractThe aim of this study was to elucidate the embryological origins of the unique neuronal progenitor cells that form the rostral migratory stream (RMS), the path traversed by cells from the anterior part of the forebrain subventricular zone (SVZa) en route to the olfactory bulb. To determine when and where cells constituting the RMS initially exhibit their characteristic neuronal phenotype and high mitotic capacity, we analyzed the cells of the rat forebrain between embryonic day 14 (E14) and postnatal day 2 (P2). At E14, cells with a neuronal phenotype were observed within the ventricular zone in close proximity to the mantle layer of the future olfactory bulb. By E15, cells expressing neuronal markers are also PSA‐NCAM immunoreactive and become aligned in chains of similarly oriented cells, a hallmark of the postnatal RMS. The cells that form chains organize into a patch that enlarges in the anterior‐posterior and medial‐lateral dimensions from E16 to E22 (birth). In comparing the forebrain cytoarchitecture to the pattern of cell type‐specific staining, the patch constitutes only the central part of the proximal RMS. Early during development, the region of the RMS surrounding the patch expresses low levels of PSA‐NCAM and neuron‐specific markers. The proliferative activity of cells forming the patch vs. nonpatch regions of the RMS was analyzed following a short bromodeoxyuridine (BrdU) exposure. Between E15 and E22, the patch can be recognized by the mitotic activity of its cells; the cells of the patch incorporate less BrdU than the nonpatch portion of the RMS. The time course of appearance of cells forming the RMS indicates that the RMS arises in advance and independently of the cortical SVZ. Although the patch and the nonpatch regions of the embryonic RMS appear to merge postnatally, the two regions may originate separately under the influence of distinct intrinsic and extrinsic factors. J. Comp. Neurol. 463:402–418, 2003. © 2003 Wiley‐Liss, Inc.
Solubility studies on valdecoxib in the presence of carriers, cosolvents, and surfactants
Authors: Desai Kashappa Goud H. , Park Hyun J. 
Published: October 2004

AbstractEnhancement of the solubility of valdecoxib was examined using a series of hydrophilic carriers (mannitol, polyethylene glycol (PEG) 4000, PEG 6000, PEG 8000, and urea), surfactants (Tween‐20, Tween‐80, and sodium lauryl sulfate [SLS]) and cosolvents (ethanol, methanol, and glycerol) at 37°C. The solubility of valdecoxib could be enhanced significantly using PEG 4000 as a carrier, ethanol as cosolvent, and SLS as a surfactant. Because the solubility of valdecoxib increased dramatically in the presence of polyethylene glycols, these are suitable dispersing agents for preparing solid dispersions containing valdecoxib. Gibbs free energy (ΔG) values were all negative for all hydrophilic carriers tested, indicating the spontaneous nature of valdecoxib solubilisation. Among the cosolvents, ethanol exhibited higher solubilization potential than methanol and glycerol. As the dielectric constant of the cosolvent–water mixtures decreased, the solubility of valdecoxib increased. Finally, SLS exerted maximum solubilization of valdecoxib when compared to Tween‐20 or Tween‐80. The crystallinity of valdecoxib was explored by X‐ray diffraction study and showed numerous crystalline peaks. Examination of surface morphology by scanning electron microscopy depicted a near spherical shape of valdecoxib with irregular surface characteristics. Drug Dev. Res. 62:41–48, 2004. © 2004 Wiley‐Liss, Inc.
Msx2 controls ameloblast terminal differentiation
Authors: Bei Marianna , Stowell Stephanie , Maas Richard 
Published: October 2004

AbstractLate tooth morphogenesis is characterized by a series of events that determine cusp morphogenesis and the histodifferentiation of epithelial cells into enamel‐secreting ameloblasts. Mice lacking the homeobox gene Msx2 exhibit defects in cusp morphogenesis and in the process of amelogenesis. To better understand the basis of the Msx2 mutant tooth defects, we have investigated the function of Msx2 during late stages of tooth morphogenesis. Cusp formation is thought to be under the control of the enamel knot, which has been proposed to act as an organizing center during this process (Vaahtokari et al. [ 1996] Mech. Dev. 54:39–43). Bone morphogenetic protein‐4 (BMP4) has been suggested to mediate termination of enamel knot signaling by means of regulation of programmed cell death (Jernvall et al. [ 1998] Development 125:161–169). Here, we show that Bmp4 expression in the enamel knot is Msx2‐dependent. We further show that during amelogenesis Msx2 is required for the expression of the extracellular matrix gene Laminin 5 alpha 3, which is known to play an essential role during ameloblast differentiation. This result thus provides a paradigm for understanding how transcription factors and extracellular matrix can be integrated into a developmental pathway controlling cell differentiation. Developmental Dynamics 231:758–765, 2004. © 2004 Wiley‐Liss, Inc.
Partially overlapping expression of Gata2 and Gata3 during inner ear development
Authors: Lilleväli Kersti , Matilainen Tanja , Karis Alar , Salminen Marjo 
Published: October 2004

AbstractGata2 and Gata3 belong to the Gata family of transcription factors in vertebrates that bind to a consensus “GATA” DNA sequence. The Gata3 gene is one of the earliest markers for the developing mouse inner ear. Ear morphogenesis is blocked in Gata3‐deficient embryos, whereas nothing was known of the role of Gata2 in mouse inner ear. Here, we have compared the expression patterns of Gata2 and Gata3 during normal inner ear development and investigated their relationship in mice where either Gata3 or Gata2 has been inactivated. The expression of the two Gata genes is highly overlapping at embryonic day (E)10.5 but becomes increasingly distinct later. Whereas Gata2 is predominantly expressed in the dorsal vestibular system, Gata3 was detected mainly in the ventral cochlear duct and ganglion. No phenotypic abnormalities were observed in the inner ear of Gata2−/− embryos before lethality at E10.5 and Gata3 expression was unchanged. In contrast, a delay and strong reduction of Gata2 expression was detected in Gata3−/− otic epithelium. Developmental Dynamics 231:775–781, 2004. © 2004 Wiley‐Liss, Inc.