bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental regulation of globin gene expression
Authors: Minie Mark , Clark David , Trainor Cecelia , Evans Todd , Reitman Marc , Hannon Robert , Gould Hannah , Felsenfeld Gary 
Published: May 2013

ABSTRACT
We have used the globin family of genes in chicken to study developmental regulation of gene expression, both at the level of individual interaction of trans-acting factors with local promoters and enhancers, and at the level of chromatin structure. Regulation of all members of the a- and [3-globin clusters is affected by the erythroid regulatory factor GATA-1. Separate mechanisms exist for regulation of individual members of the family. As an example, we describe the control mechanisms that play a role in the expression of the p-globin gene, which is expressed only in primitive lineage erythroid cells. In addressing the involvement of chromatin structure in gene activation, we have examined the role of locus control elements, and also considered the way in which RNA polymerase molecules might accommodate to the presence of nucleosomes on transcribed genes.
Retinoid receptors and binding proteins
Authors: Lohnes David , Dierich Andrée , Ghyselinck Norbert , Kastner Phillipe , Lampron Carmen , Lemeur Marianne , Lufkin Thomas , Mendelsohn Cathy , Nakshatri Hari , Chambon Pierre 
Published: May 2013

ABSTRACT
Retinoids, in particular all-trans retinoic acid (T-RA), are essential for normal development and homeostasis of vertebrates. Although many effects of retinoids, particularity with regard to teratogenicity, have been described in the literature, the mechanisms by which these simple signalling molecules work has only recently begun to be elucidated. We now recognize at least two classes of retinoid-binding proteins and two families of retinoid receptors. The ultimate interpretation of the retinoid signal within a given cell is probably the result of a complex series of interactions between these proteins, yet little is understood concerning the role each member of this signalling pathway plays. It is therefore imperative to dissect the molecular mechanisms which transduce the effects of these ligands, both in vivo and in isolated systems. One approach we are employing is gene targeting of retinoic acid receptors (RARs) and cellular retinoid-binding proteins to generate mice in which one or more of these genes has been functionally inactivated.
Synaptic vesicle proteins and regulated exocytosis
Authors: Elferink Lisa A. , Scheller Richard H. 
Published: May 2013

ABSTRACT
The recent identification of novel proteins associated with the membranes of synaptic vesicles has ignited the field of molecular neurobiology to probe the function of these molecules. Evidence is mounting that the vesicle proteins vamp (synaptobrevin), rab3A, synaptophysin, synaptotagmin (p65) and SV2 play an important role in regulated exocytosis, by regulating neurotransmitter uptake, vesicle targeting and fusion with the presynaptic plasma membrane.
Membrane traffic in polarized neurons in culture
Authors: Hoop Meltsje J. de , Dotti Carlos G. 
Published: May 2013

ABSTRACT
Fetal hippocampal neurons develop axons and dendrites in culture. To study how neurons form and maintain different plasma membrane domains, hippocampal neurons were infected with RNA viruses and the distribution of the viral glycoproteins was analyzed by light and electron microscopy. Infection of hippocampal cells with vesicular stomatitis virus (VSV) and fowl plague virus (FPV) resulted in the polarized distribution of the newly synthesized viral glycoproteins. The VSV glycoprotein appeared firstly in the Golgi apparatus and then in the dendrites. In contrast, the hemagglutinin of FPV, after accumulation in the Golgi apparatus, moved to the axons. These results suggest that the mechanism of sorting of viral glycoproteins might be similar in neurons and MDCK cells, a cell line of epithelial origin. In these cells the VSV glycoprotein and the hemagglutinin of FPV distribute to the basolateral and apical membranes, respectively. Transport of viral glycoproteins to both neuronal domains was microtubule dependent. Nocoda- zole treatment of infected neurons inhibited the delivery of axonal and dendritic viral glycoproteins equally.
To investigate if the analogy between epithelial cells and neurons extended to include an endogenous plasma membrane protein, the distribution of Thy-1, a GPI- linked protein, was analyzed. By immunofluorescence and immunoelectron microscopy, Thy-1 was found exclusively along the axonal surface. In epithelial cells GPI-anchored proteins are located apically.
The existence of a barrier on the neuronal plasma membrane that would prevent intermixing of axonal and dendritic proteins was analyzed by a liposomefusion assay. Fluorescently labeled liposomes containing the GDia ganglioside were added to FPV-infected neurons. The liposomes bound specifically to the hemagglutinin protein, expressed on the axonal surface. After fusion, fluorescent labelling was observed along the axon but not diffusing into the cell body and dendrites. The barrier that prevented lipid diffusion appeared to be located in the axonal hillock region.
Our work shows that experimental strategies that have proven useful in the understanding of membrane sorting in epithelial cells, can also be used to unveil the mechanism of neuronal sorting.
Traffic of synaptic vesicle proteins in polarized and nonpolarized cells
Authors: Cameron Patricia , Mundigl Olaf , Camilli Pietro De 
Published: May 2013

ABSTRACT
Neurons have at least two pathways of regulated secretion, which involve two classes of secretory organelles: typical synaptic vesicles (SVs) and large dense-core vesicles. Large dense-core vesicles store and secrete peptide neurotransmitters and amines, and may be seen as the neuronal counterpart of secretory granules of endocrine cells. SVs are highly specialized secretory organelles, which store and secrete non-peptide hormones and play a dominant role in the fast, point-to-point signalling typical of the nervous system. Microvesicles that share a variety of biochemical and functional similarities with SVs (synaptic-like micro vesicles) have recently been described in endocrine cells. SVs and synaptic-like microvesicles are closely related to vesicular carriers of the receptor-mediated recycling pathway. They undergo repeated cycles of exo-endocytosis, which are thought to involve endosomal intermediates.
In mature neurons, SVs are concentrated in axon endings. To gain insight into the mechanisms responsible for SV targeting, we have studied the traffic of SV proteins in both endocrine cells and developing hippocampal neurons in primary culture at different stages of differentiation. Additionally, the distribution of the SV protein synaptophysin, when expressed by transfection in fibroblastic cells or in polarized epithelial cells (MDCK cells), was investigated.
SV proteins are already present in developing neurons at stages preceding the establishment of neuronal polarity. As axons and dendrites form, SV proteins are found in both types of processes, although they become progressively more concentrated in the axon. Throughout these developmental stages SVs undergo active exo-endocytotic recycling. The nonpolarized distribution of SV proteins is observed even at stages when the transferrin receptor, a protein that is present in epithelial cells only at the basolateral surface, is already restricted to dendrites. This indicates that, in immature neurons, SV proteins are not selectively targeted to axons and that the accumulation in axons may at least partially result from a specific retention. In agreement with this finding, synaptophysin, when transfected into MDCK cells, was targeted to both the basolateral and the apical plasma membrane. Brefeldin A, a fungal metabolite that induces a modification of the steady-state localization of endosomal proteins in a variety of cell types, was found to have a different effect on the distribution of SV proteins in dendrites and in axons. Taken together, these observations support the existence of two separate endosomal systems in axons and dendrites, which have differential properties, are enriched in different proteins, and may be related to the basolateral and apical endosomes of epithelial cells.
Biogenesis of structural intercellular junctions during cleavage in the mouse embryo
Authors: Fleming Tom P. , Javed Qamar , Collins Jane , Hay Mark 
Published: May 2013

ABSTRACT
The preimplantation embryo differentiates the trophec-toderm epithelium which, from the 32-cell stage, generates the blastocoel of the blastocyst and, after implantation, gives rise to most extraembryonic lineages of the conceptus. Trophectoderm differentiation begins at compaction (8-cell stage) when cell-cell adhesion, mediated by uvomorulin, and epithelial cell polarisation first occur. Here, we review our work on the biogenesis of tight junctions and desmosomes during epithelial differentiation. Tight junction construction begins at compaction and appears to be a gradual process, both at morphological and molecular levels. This maturation pattern may be due in part to sequential expression of tight junction constituents from the embryonic genome. Tight junction formation is dependent upon uvomorulin adhesion but can be inhibited by different means without apparently disturbing cell adhesion or polarisation. Cell interactions appear to regulate tight junction tissue specificity, in part by controlling the level of synthesis of constituents. Desmosome formation begins at the 32cell stage, particularly as the embryo initiates blastocoel accumulation, and, in contrast with tight junction formation, does not appear to be a gradual process. Thus, nascent desmosomes appear mature in terms of their molecular composition. Desmosomal proteins are synthesised well in advance of desmosome formation but the synthesis of the principal glycoprotein components begins at the blastocyst stage and may regulate the timing of junction assembly. Implications of these differing patterns of biogenesis for the embryo are discussed.
Epithelial cell adhesion and development of cell surface polarity: possible mechanisms for modulation of cadherin function, organization and distribution
Authors: Näthke Inke S. , Hinck Lindsay E. , Nelson W. James 
Published: May 2013

ABSTRACT
Epithelial cell adhesion is principally regulated by calcium-dependent cell adhesion proteins, termed cadherins. Recent studies indicate that cadherin function is modulated by a class of proteins, termed catenins, that bind to the cytoplasmic domain of cadherin. Here we review the evidence that catenins regulate cadherin function in cell-cell adhesion, and discuss their role in inititiating cell surface polarity in epithelial cells.
Protein traffic in polarized epithelial cells: the polymeric immunoglobulin receptor as a model system
Authors: Mostov Keith 
Published: May 2013

ABSTRACT
As a model system to study protein traffic in polarized epithelial cells, we have used the polymeric immunoglobulin receptor. This receptor travels first to the basolateral surface, where it can bind polymeric IgA or IgM. The receptor is then endocytosed and delivered to endosomes. The receptor is sorted into transcytotic vesicles, which are exocytosed at the apical surface. The 103-amino acid cytoplasmic domain of the receptor contains several sorting signals. The 17 residues closest to the membrane are an autonomous signal that is necessary and sufficient for basolateral sorting. For rapid endocytosis there are two independent signals, both of which contain critical tyrosine residues. Finally, transcytosis is signaled by phosphorylation of a particular serine.
Role of heterotrimeric G proteins in polarized membrane transport
Authors: Pimplikar Sanjay W. , Simons Kai 
Published: May 2013

ABSTRACT
MDCK cells maintain the polarized distribution of surface proteins mainly by sorting the newly synthesized proteins in the irans-Golgi network (TGN). In order to identify the components of the putative sorting machinery and to study factors that affect the sorting process, we have developed an in vitro system that reconstitutes the transport of viral glycoproteins from the TGN to the apical or basolateral surface. We have used this system to study effects of membrane impermeable reagents (such as peptides and antibodies) on the polarized transport. We observed that reagents affecting the stimulatory class (Gs) of heterotrimeric GTP binding proteins (G proteins) influenced the apical but not the basolat-eral transport. In contrast, reagents specific for the inhibitory class of G proteins (Gi) affected the basolateral but not the apical transport. These results show that the heterotrimeric G proteins differentially regulate the two pathways of polarized transport. The G proteins may regulate the process of polarized sorting of proteins in a fashion analogous to their role in signal transduction by providing a communication link with the cytosolic side of the membrane.
Endosomal pathways for water channel and proton pump recycling in kidney epithelial cells
Authors: Brown Dennis , Sabolic Ivan 
Published: May 2013

ABSTRACT
The plasma membrane composition of virtually all eukaryotic cells is maintained and continually modified by the recycling of specific protein and lipid components. In the kidney collecting duct, urinary acidification and urinary concentration are physiologically regulated at the cellular level by the shuttling of proton pumps and water channels between intracellular vesicles and the plasma membrane of highly specialized cell types. In the intercalated cell, hydrogen ion secretion into the urine is modulated by the recycling of vesicles carrying a proton pumping ATPase to and from the plasma membrane. In the principal cell, the antidiuretic hormone, vasopressin, induces the insertion of vesicles that contain proteinaceous water channels into the apical cell membrane, thus increasing the permeability to water of the epithelial layer. In both cell types, ‘coated’ carrier vesicles are involved in this process, but whereas clathrin-coated vesicles are involved in the endocytotic phase of water channel recycling, the transporting vesicles in intercalated cells are coated with the cytoplasmic domains of the proton pumping ATPase. By a combination of morphological and functional techniques using FITC-dextran as an endosomal marker, we have shown that recycling endosomes from intercalated cells are acidifying vesicles but that they do not contain water channels. In contrast, principal cell vesicles that recycle water channels do not acidify their lumens in response to ATP. These non-acidic vesicles lack functionally important subunits of the vacuolar proton ATPase, including the 16 kDa proteolipid that forms the transmembrane proton pore. Because these endosomes are directly derived via clathrin-mediated endocytosis, our results indicate that endocytotic clathrin-coated vesicles are non-acidic compartments in principal cells. In contrast, recycling vesicles in intercalated cells contain large numbers of proton pumps, arranged in hexagonally packed arrays on the vesicle membrane. These pumps are inserted into the apical plasma membrane of A-type (acid-secreting) intercalated cells, and the baso-lateral plasma membrane of B-type (bicarbonate-secreting) cells in the collecting duct. Both apical and baso-lateral targeting of H+-ATPase-containing vesicles in these cells may be directed by microtubules, because polarized insertion of the pump into both membrane domains is disrupted by microtubule depolymerizing agents. However, the basolateral localization of other transporting proteins in intercalated cells, including the band 3-like anion exchanger and facilitated glucose transporters, is not affected by microtubule disruption.
The role of PRP8 protein in nuclear pre-mRNA splicing in yeast
Authors: Beggs Jean D. , Teigelkamp Stefan , Newman Andrew J. 
Published: May 2013

ABSTRACT
The removal of introns from precursor messenger RNAs occurs in a large complex, the spliceosome, that contains many proteins and five small nuclear RNAs (snRNAs). The snRNAs interact with the intron-containing substrate RNA and with each other to form a dynamic network of RNA interactions that define the intron and promote splicing. There is evidence that protein splicing factors play important roles in regulating RNA interactions in the spliceosome. PRP8 is a highly conserved protein that is associated in particles with the U5 snRNA and directly binds the substrate RNA in spliceosomes. UV crosslinking has been used to map the binding sites, and shows extensive interaction between PRP8 protein and the 5′exon prior to the first step of splicing and with the 3′splice site region subsequently. It is proposed that PRP8 protein may stabilize fragile interactions between the U5 snRNA and exon sequences at the splice sites, to anchor and align them in the catalytic centre of the spliceosome.
Studies of DNA methylation in animals
Authors: Bird Adrian , Tate Peri , Nan Xinsheng , Campoy Javier , Meehan Richard , Cross Sally , Tweedie Susan , Charlton Jillian , Macleod Donald 
Published: May 2013

ABSTRACT
We have been studying the evolution and function of DNA methylation in vertebrate animals using three related approaches. The first is to further characterise proteins that bind to methylated DNA. Such proteins can be viewed as ‘receptors′ of the methyl-CpG ‘ligand’ that mediate downstream consequences of DNA modification. The second approach involves CpG islands. These patches of non-methylated DNA coincide with most gene promoters, but their origin and functional significance have only recently become the subject of intensive study. The third approach is to trace the evolution of DNA methylation. Genomic methylation patterns of vertebrates are strikingly different from those of invertebrates. By studying methylation in animals that diverged from common ancestors near to the invertebrate/vertebrate boundary, we will assess the possibility that changes in DNA methylation contributed causally to the evolution of the complex vertebrate lineage.
Remarkable Effect of Bases on Core–Shell AgNP@CeO2 Nanocomposite-catalyzed Highly Chemoselective Reduction of Unsaturated Aldehydes
Authors: Mitsudome Takato , Matoba Motoshi , Yamamoto Masaaki , Mizugaki Tomoo , Jitsukawa Koichiro , Kaneda Kiyotomi 
Published: May 2013

Abstract
A highly dispersed core–shell silver nanoparticle–ceria nanocomposite catalyst (AgNP@CeO2-D) was prepared. The addition of bases was found to enhance the catalytic efficiency of AgNP@CeO2-D significantly in the chemoselective reduction of diverse unsaturated aldehydes to the corresponding unsaturated alcohols.
Speech Perception in Children Under Noisy Situations
Authors: Monteiro Natália Fernanda Garro , Molina Samira Vilela , Bevilacqua Maria Cecília , Lauris José Roberto Pereira , Moret Adriane Lima Mortari , Jacob Regina Tangerino de Souza 
Published: May 2013

Summary
Introduction: The ability to understand speech is impaired by many factors during evaluations, especially under noise, and it is still more complex for children under these conditions.
Objective: To analyze the speech perception in children with a normal hearing in different noise situations.
Method: Way of study transverse section. The Brazilian Hearing in Noise Test (HINT) was performed in 21 children aged between 7 and 14 with a standard hearing and no cognitive alterations. The sentence lists were randomly used in these situations: silence (S), frontal noise (FN); right-side noise (RN); left-side noise (LN); noise at 180°. (RT) and a comparison between the result of the compound noise (CN) and the diffuse noise in four sound areas at 45°; 135°; 225° e 315° (4 BXS).
Results: The statistical analysis showed a significant difference among the following situations: RN with FN; BN with FN; and it was worse with 4 BXS, where a difference for RN, BN, CN, LN and FN was found. To analyze a correlation with age, it was significant regarding the age, as a result of HINT values only for the frontal noise.
Conclusion: The significant differences in the results of speech perception among the different hearing conditions in the evaluated individuals suggest carefulness when choosing the stimulus in evaluations of speech perception in the noise in hearing-impaired children. Accordingly, researches in this field are necessary to determine the standards and variations related to its application and result interpretation.
On the generalized Davenport constant and the Noether number
Authors: Cziszter Kálmán , Domokos Mátyás 
Published: May 2013

Abstract
Known results on the generalized Davenport constant relating zero-sum sequences over a finite abelian group are extended for the generalized Noether number relating rings of polynomial invariants of an arbitrary finite group. An improved general upper degree bound for polynomial invariants of a non-cyclic finite group that cut out the zero vector is given.
Assessment of snowmelt runoff modelling and isotope analysis: a case study from the western Himalaya, India
Authors: Ahluwalia Rajeev Saran , Rai S.P. , Jain Sanjay K. , Kumar Bhishm , Dobhal D.P. 
Published: May 2013

AbstractThe major river systems of India, i.e. the Indus, Ganga and Brahmaputra river systems originating in the Himalayan region, are considered the lifeline of the Indian subcontinent. The main sources maintaining the flow of the Himalayan rivers are snow/glacial melt runoff, rainfall runoff and base flow. The Beas River originates from Beas Kund Glacier in the Himalayan region and flows down to join the Sutlej River, which is a tributary of the Indus River system. In the present study two approaches, namely hydrologic modelling and isotope analysis, have been applied to estimate the contribution of snow and glacier melt. Samples of streamflow, rainfall and snow for isotopic analysis were collected daily from April to September and weekly from October to March during 2010 and 2011. The isotope analysis of samples reveals that the snow/glacier melt contribution to the Beas River at Manali is 50% of the total flow during these 2 years. Snowmelt runoff modelling has been carried out using the SNOWMOD model, and the snow/glacier melt runoff contribution is calculated to be 52% of the total flow during the same period. These findings indicate that the results obtained from the two approaches are similar.
Multiscale spatial variability of lidar-derived and modeled snow depth on Hardangervidda, Norway
Authors: Melvold Kjetil , Skaugen Thomas 
Published: May 2013

AbstractThis study presents results from an Airborne Laser Scanning (ALS) mapping survey of snow depth on the mountain plateau Hardangervidda, Norway, in 2008 and 2009 at the approximate time of maximum snow accumulation during the winter. The spatial extent of the survey area is >240 km2. Large variability is found for snow depth at a local scale (2 m2), and similar spatial patterns in accumulation are found between 2008 and 2009. The local snow-depth measurements were aggregated by averaging to produce new datasets at 10, 50, 100, 250 and 500 m2 and 1 km2 resolution. The measured values at 1 km2 were compared with simulated snow depth from the seNorge snow model (www.senorge.no), which is run on a 1 km2 grid resolution. Results show that the spatial variability decreases as the scale increases. At a scale of about 500 m2 to 1 km2 the variability of snow depth is somewhat larger than that modeled by seNorge. This analysis shows that (1) the regional-scale spatial pattern of snow distribution is well captured by the seNorge model and (2) relatively large differences in snow depth between the measured and modeled values are present.