bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurospora Spore KillersSk-2andSk-3Suppress Meiotic Silencing by Unpaired DNA
Authors: Raju Namboori B , Metzenberg Robert L , Shiu Patrick K T 
Published: March 2007

AbstractIn Neurospora crassa, pairing of homologous DNA segments is monitored during meiotic prophase I. Any genes not paired with a homolog, as well as any paired homologs of that gene, are silenced during the sexual phase by a mechanism known as meiotic silencing by unpaired DNA (MSUD). Two genes required for MSUD have been described previously: sad-1 (suppressor of ascus dominance), encoding an RNA-directed RNA polymerase, and sad-2, encoding a protein that controls the perinuclear localization of SAD-1. Inactivation of either sad-1 or sad-2 suppresses MSUD. We have now shown that MSUD is also suppressed by either of two Spore killer strains, Sk-2 and Sk-3. These were both known to contain a haplotype segment that behaves as a meiotic drive element in heterozygous crosses of killer × sensitive. Progeny ascospores not carrying the killer element fail to mature and are inviable. Crosses homozygous for either of the killer haplotypes suppress MSUD even though ascospores are not killed. The killer activity maps to the same 30-unit-long region within which recombination is suppressed in killer × sensitive crosses. We suggest that the region contains a suppressor of MSUD.
Neutral Evolution of Multiple Quantitative Characters: A Genealogical Approach
Authors: Griswold Cortland K , Logsdon Benjamin , Gomulkiewicz Richard 
Published: March 2007

AbstractThe G matrix measures the components of phenotypic variation that are genetically heritable. The structure of G, that is, its principal components and their associated variances, determines, in part, the direction and speed of multivariate trait evolution. In this article we present a framework and results that give the structure of G under the assumption of neutrality. We suggest that a neutral expectation of the structure of G is important because it gives a null expectation for the structure of G from which the unique consequences of selection can be determined. We demonstrate how the processes of mutation, recombination, and drift shape the structure of G. Furthermore, we demonstrate how shared common ancestry between segregating alleles shapes the structure of G. Our results show that shared common ancestry, which manifests itself in the form of a gene genealogy, causes the structure of G to be nonuniform in that the variances associated with the principal components of G decline at an approximately exponential rate. Furthermore we show that the extent of the nonuniformity in the structure of G is enhanced with declines in mutation rates, recombination rates, and numbers of loci and is dependent on the pattern and modality of mutation.
Genetic Positioning of Centromeres Using Half-Tetrad Analysis in a 4x–2xCross Population of Potato
Authors: Park Tae-Ho , Kim Jong-Bo , Hutten Ronald C B , van Eck Herman J , Jacobsen Evert , Visser Richard G F 
Published: March 2007

AbstractFrom biological and genetic standpoints, centromeres play an important role in the delivery of the chromosome complement to the daughter cells at cell division. The positions of the centromeres of potato were determined by half-tetrad analysis in a 4x–2x population where the male parent produced 2n pollen by first-division restitution (FDR). The genetic linkage groups and locations of 95 male parent-derived amplified fragment length polymorphism markers could be determined by comparing their position on a 2x–2x highly saturated linkage map of potato. Ten centromere positions were identified by 100% heterozygosity transmitted from the 2n heterozygous gametes of the paternal parent into the tetraploid offspring. The position of these centromeric marker loci was in accordance with those predicted by the saturated 2x–2x map using the level of marker clustering as a criterion. Two remaining centromere positions could be determined by extrapolation. The frequent observation of transmission of 100% heterozygosity proves that the meiotic restitution mechanism is exclusively based on FDR. Additional investigations on the position of recombination events of three chromosomes with sufficient numbers of markers showed that only one crossover occurred per chromosome arm, proving strong interference of recombination between centromere and telomere.
Phylogenetic and Genomewide Analyses Suggest a Functional Relationship Betweenkayak, the Drosophila Fos Homolog, andfig, a Predicted Protein Phosphatase 2C Nested Within akayakIntron
Authors: Hudson Stephanie G , Garrett Matthew J , Carlson Joseph W , Micklem Gos , Celniker Susan E , Goldstein Elliott S , Newfeld Stuart J 
Published: March 2007

AbstractA gene located within the intron of a larger gene is an uncommon arrangement in any species. Few of these nested gene arrangements have been explored from an evolutionary perspective. Here we report a phylogenetic analysis of kayak (kay) and fos intron gene (fig), a divergently transcribed gene located in a kay intron, utilizing 12 Drosophila species. The evolutionary relationship between these genes is of interest because kay is the homolog of the proto-oncogene c-fos whose function is modulated by serine/threonine phosphorylation and fig is a predicted PP2C phosphatase specific for serine/threonine residues. We found that, despite an extraordinary level of diversification in the intron–exon structure of kay (11 inversions and six independent exon losses), the nested arrangement of kay and fig is conserved in all species. A genomewide analysis of protein-coding nested gene pairs revealed that ∼20% of nested pairs in D. melanogaster are also nested in D. pseudoobscura and D. virilis. A phylogenetic examination of fig revealed that there are three subfamilies of PP2C phosphatases in all 12 species of Drosophila. Overall, our phylogenetic and genomewide analyses suggest that the nested arrangement of kay and fig may be due to a functional relationship between them.
Neuromotor Outcome at 2 Years of Very Preterm Infants Who Were Treated With High-Frequency Oscillatory Ventilation or Conventional Ventilation for Neonatal Respiratory Distress Syndrome
Authors: Truffert Patrick , Paris-Llado Josefa , Escande Benoît , Magny Jean-François , Cambonie Gilles , Saliba Elie , Thiriez Gérard , Zupan-Simunek Véronique , Blanc Thierry , Rozé Jean-Christophe , Bréart Gérard , Moriette Guy 
Published: March 2007

OBJECTIVE. In a previous multicenter, randomized trial, elective use of high-frequency oscillatory ventilation was compared with the use of conventional ventilation in the management of respiratory distress syndrome in preterm infants &lt;30 weeks. No difference in terms of respiratory outcome was observed, but concerns were raised about an increased rate of severe intraventricular hemorrhage in the high-frequency ventilation group. To evaluate outcome, a follow-up study was conducted until a corrected age of 2 years. We report the results concerning neuromotor outcome.
METHODS. Outcome was able to be evaluated in 192 of the 212 infants who survived until discharge from the neonatal unit: 97 of 105 infants of the high-frequency group and 95 of 104 infants of the conventional ventilation group.
RESULTS. In the infants reviewed, mean birth weight and gestational age were similar in the 2 ventilation groups. As in the overall study population, the following differences were observed between the high-frequency ventilation group and the conventional ventilation group: lower 5-minute Apgar score, fewer surfactant instillations, and a higher incidence of severe intraventricular hemorrhage. At a corrected age of 2 years, 93 of the 97 infants of the high-frequency group and 79 of the 95 infants of the conventional ventilation group did not present any neuromotor disability, whereas 4 infants of the high-frequency group and 16 infants of the conventional ventilation group had cerebral palsy.
CONCLUSIONS. Contrary to our initial concern about the increased rate of severe intraventricular hemorrhage in the high-frequency ventilation group, these data suggest that early use of high-frequency ventilation, compared with conventional ventilation, may be associated with a better neuromotor outcome. Because of the small number of patients studied and the absence of any explanation for this finding, we can conclude only that high-frequency oscillatory ventilation is not associated with a poorer neuromotor outcome.
Transcriptional profiling of subjects from the Iowa adoption studies
Authors: Philibert Robert A. , Ryu Gi‐Yung , Yoon Jae‐Geun , Sandhu Harinder , Hollenbeck Nancy , Gunter Tracy , Barkhurst Amanda , Adams William , Madan Anup 
Published: March 2007

AbstractTranscriptional profiling has been used to identify gene expression patterns indicative of general medical illnesses such as atherosclerosis. However, whether these methods can identify common psychiatric disorders has not been established. To answer this question with respect to nicotine use, we used genome‐wide expression profiling lymphoblast cell lines from six actively smoking Iowa Adoption Studies (IAS) subjects and nine “clean” control subjects, followed by real‐time PCR (RT‐PCR) of gene expression patterns in lymphoblast derived RNA from 94 subjects in the IAS. As compared to those from controls without a history of smoking (n = 9), the expression levels of 579 of 29,098 genes were significantly up‐regulated and expression levels of 584 of 29,098 genes were significantly down‐regulated in lymphoblast lines from currently smoking subjects (n = 6). RT‐PCR confirmation of four select RNA levels confirmed the validity of the overall profile and revealed highly significant relationships between the expression of some of these transcripts and (1) major depression, (2) antisocial personality, (3) nicotine dependence, and (4) cannabis dependence. We conclude that the use of expression profiling may contribute significant insights into the biology of complex behavioral disorders. © 2007 Wiley‐Liss, Inc.
Biological relationship between central and South American Chibchan speaking populations: Evidence from mtDNA
Authors: Melton Phillip E. , Briceño I. , Gómez A. , Devor E.J. , Bernal J.E. , Crawford M.H. 
Published: March 2007

AbstractWe examined mitochondrial DNA (mtDNA) haplogroup and haplotype diversity in 188 individuals from three Chibchan (Kogi, Arsario, and Ijka) populations and one Arawak (Wayuú) group from northeast Colombia to determine the biological relationship between lower Central American and northern South American Chibchan speakers. mtDNA haplogroups were obtained for all individuals and mtDNA HVS‐I sequence data were obtained for 110 samples. Resulting sequence data were compared to 16 other Caribbean, South, and Central American populations using diversity measures, neutrality test statistics, sudden and spatial mismatch models, intermatch distributions, phylogenetic networks, and a multidimensional scaling plot. Our results demonstrate the existence of a shared maternal genetic structure between Central American Chibchan, Mayan populations and northern South American Chibchan‐speakers. Additionally, these results suggest an expansion of Chibchan‐speakers into South America associated with a shift in subsistence strategies because of changing ecological conditions that occurred in the region between 10,000–14,000 years before present. Am J Phys Anthropol, 2007. © 2007 Wiley‐Liss, Inc.
Carbon nanotubes‐reinforced PET nanocomposite by melt‐compounding
Authors: Anand K Anoop , Agarwal U. S. , Joseph Rani 
Published: March 2007

AbstractPoly(ethylene terephthalate) (PET) nanocomposites with single‐walled carbon nanotubes (SWNTs) have been prepared by a simple melt compounding method. With increasing concentration (0–3 wt %) of SWNTs, the mechanical and dynamic mechanical properties improved, corresponding to effective reinforcement. Melt rheological characterization indicated the effective entanglements provided by SWNTs in the melt state as well. Thermogravimetric analysis suggested no influence of SWNTs on the thermal stability of PET. Electrical conductivity measurements on the composite films pointed out that the melt compounded SWNTs can result in electrical percolation albeit at concentrations exceeding 2 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation of grafted copolymers via oxidized polypropylene
Authors: Dang V. , Fezza R. , Shu C. , Phan T. , Song C. 
Published: March 2007

AbstractA new and novel class of oxidized polypropylene containing bound peroxide functionalities can be used as polymerization initiators to produce polypropylene‐grafted copolymers. Upon heat treatment, the peroxide functionalities in the oxidized polypropylene act as a source of free radicals, reacting with the unsaturated double bonds of the monomer and initiating polymerization. The grafting reaction is carried out in the solid state in a reactor. The advantage of grafting via this new class of oxidized polypropylene is the elimination of expensive and environmentally unfriendly organic peroxides. A number of monomers have been grafted using oxidized polypropylene, including vinyl acetate, vinyl pyrrolidinone, methacrylic anhydride, and maleic anhydride. Oxidized polypropylene‐grafted copolymers are effective compatibilizers for PP/ETP blends and good coupling agents in glass‐ reinforced formulations. Preparation, characterization, and mechanical properties of terpolymers prepared from sequential grafting of oxidized polypropylene are also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Effect of poly(ethylene‐co‐glycidyl methacrylate) compatibilizer content on the morphology and physical properties of ethylene vinyl acetate–wood fiber composites
Authors: Dikobe D. G. , Luyt A. S. 
Published: March 2007

AbstractIn this study, ethylene vinyl acetate (EVA)–wood fiber (WF) (uncompatibilized) and EVA/poly(ethylene‐co‐glycidyl methacrylate) (EGMA)‐WF (compatibilized) were blended, and their morphology as well as mechanical, thermal, O2 permeability, and water absorption properties were investigated. It is shown that there is a possible interaction between EVA and WF. This interaction seems to be very weak, and the resulting composites have poor properties. The presence of EGMA in the composite improved most of the investigated properties. IR analysis shows that there is a grafting reaction between EGMA and WF. The resulting composites have better properties than EVA or its uncompatibilized composites. The amount of compatibilizer has an effect on the properties of the composites. The mechanical properties improved with increasing EGMA content, but thermal stability decreased with increasing EGMA content. Oxygen permeability and water absorption decreased with an increase in EGMA content in the composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Die Bicentenario‐Chiloe‐Brücke: Seismische und dynamische Untersuchungen
Authors: Sadegh‐Azar Hamid 
Published: March 2007

AbstractIn diesem Beitrag wird die seismische und dynamische Analyse der Bicentenario‐Chiloe‐Brücke in Chile präsentiert. Die Brücke soll den Chacao‐Kanal (Canal De Chacao) überqueren und die Insel Chiloe mit dem Chilenischen Festland verbinden. Der vorgesehene Standort der Brücke liegt in einer der seismisch aktivsten und höchst gefährdeten Zonen der Welt. In unmittelbarer Umgebung wurde das bisher stärkste Erdbeben der Welt registriert (Valdivia‐Erdbeben von 1960 mit einer Magnitude von 9.5). Die Bemessung der Hängebrücke wird somit maßgeblich durch den Lastfall Erdbeben beeinflußt. Die besondere Herausforderung hierbei ist die genaue Berücksichtigung des Einflusses des Baugrunds auf die seismische Einwirkung und die konsistente Erfassung der Boden‐Brücken‐Wechselwirkung. In diesem Aufsatz werden einige wichtige Aspekte und Probleme der seismischen Analyse einer solchen Hängebrücke dargestellt und Lösungswege dafür aufgezeigt. Hierbei wird versucht, die teilweise etwas komplizierten Berechnungsmethoden durch verständliche Formulierungen vereinfacht darzustellen, so daß der Aufsatz für den praktizierenden Ingenieur verständlich bleibt.
Synthesis of (S)‐2‐Ethoxy‐3‐Phenylpropanoic Acid Derivatives and Their Insulin‐Sensitizing Activity
Authors: Wu Ying‐Hua 
Published: March 2007

AbstractA series of (S)‐2‐ethoxy‐3‐phenylpropanoic acid derivatives were synthesized and their insulin‐sensitizing activities were evaluated in 3T3‐L1 cells. Compounds 1b, 1d, 1e and 1f exhibited more potent insulin‐sensitizing activity than rosiglitazone.
Substituent Effect on N‐Benzylideneanilines by DFT Energy Partition
Authors: Ma Yan‐Ping , Bao Peng , Yu Zhong‐Heng 
Published: March 2007

AbstractTo investigate the substituent effect on π‐electron delocalization of the N‐benzylideneaniline (NBA), the vertical resonance energies ΔEV(θ) of eleven substituted NBAs were separated into π and σ parts at the B3LYP/6‐311G(d) level of the Density Functional Theory (DFT). When substituted with an electron‐releasing group –OH, the calculated ΔEV(θ) of NBA was increased, indicative of more resonance destabilization than the mother molecule. However, when substituted with an electron‐withdrawing group –NO2, the calculated ΔEV(θ) values indicated less resonance destabilization. The most destabilizing effect was observed especially when the
–OH group located at the ortho‐position of the aromatic ring in the fragment –NCH–Ar. For most of the substituted NBA molecules, it was the destabilized σ framework that determined the destabilizing feature of the vertical resonance energy, instead of the stabilized π system. When the –NO2 substituent at the para‐position of the aromatic ring of the –NCH–Ar group, the π system had the highest stabilizing effect while the ( framework exhibited the highest destabilizing effect. While the –NO2 substituent was at the para‐position of the left aromatic ring (Ar–), the NBA had the least vertical resonance energy value.
Study on the Supramolecular Interaction of β‐Cyclodextrin with Gemfibrozil by Spectrofluorimetry and Its Analytical Application
Authors: Huang Hui , Liu Fang , Jia Bao‐Xiu , Xu Ke‐Hua , Chen Zhen‐Zhen , Tang Bo 
Published: March 2007

AbstractThe supramolecular interaction of gemfibrozil with β‐cyclodextrin (β‐CD) was studied by spectrofluorimetry. The mechanism of the inclusion was discussed by spectrofluoremetry, infrared spectrum and 1H NMR spectrum. The results showed that a 1:1 (β‐CD:gemfibrozil) complex was formed with an apparent association constant of 3.844×103 L·mol−1. Based on the enhancement of the fluorescent intensity of gemfibrozil, a spectrofluorimetric method for the determination of gemfibrozil in bulk aqueous solution in the presence of β‐CD was developed. The linear range was 3.30 ng·mL−1–6.00 µg·mL−1 with the detection limit of 0.980 ng·mL−1. There was no interference from the excipients normally used in tablet composition and the serum main compositions. The proposed method was then successfully applied to the determination of gemfibrozil in capsules and serum.
A Novel Electrogenerated Chemiluminescence Reaction Scheme Using Core‐Shell Luminol‐Based SiO2 Nanoparticles as a Regulator and Its Analytical Application
Authors: Zhang Li‐Li , Zheng Xing‐Wang , Guo Zhi‐Hui 
Published: March 2007

AbstractA novel core‐shell luminol‐based SiO2 nanoparticle was synthesized by two step micro‐emulsion method. While these nanoparticles were used as electrogenerated chemiluminescence (ECL) reagent, the electrochemical (EC) reaction as well as the subsequent chemiluminescence (CL) reaction not only could be separated spatially, but also presented high efficiency for analytical purpose. In this case, the core‐shell luminol‐based SiO2 nanoparticles offered more potential to avoid the contradiction between the EC and the CL reaction conditions. A new ECL method based on the nanoparticle was developed, and isoniazid was selected as a model analyte to illustrate the characteristics of this new ECL method. Under the selected conditions, the proposed ECL response to isoniazid concentration was linear in the range of 1.0×10−10 to 1.0×10−6 g/mL with 2×10−11 g/mL detection limit.
Highly Efficient One‐Pot Synthesis of 2‐Arylmethyl N‐Substituted Anilines via Yb(OTf)3 Catalyzed Three‐Component Reaction
Authors: Wang Li‐Min , Zhang Liang , Hu Liang , Tian He 
Published: March 2007

AbstractAn efficient method has been developed for one‐pot three‐component coupling reactions of various aldehydes, 1‐cyclohexen‐2‐one, and primary or secondary amines in the presence of a catalytic amount of Yb(OTf)3 under mild conditions to afford the corresponding 2‐arylmethyl N‐substituted anilines in good yields. In addition, the catalyst was easily recovered and could be reused for at least four cycles without any loss of activity.
Synthesis and Enantioselective Discrimination of Chiral Fluorescence Receptors Bearing Amino Acid Units
Authors: Xu Kuo‐Xi , He Yong‐Bing , Qing Guang‐Yan , Qin Hai‐Juan , Liu Shun‐Ying , Meng Ling‐Zhi 
Published: March 2007

AbstractTwo chiral fluorescence receptors (1, 2) were synthesized, and their structures were characterized by IR, 1H NMR, 13C NMR, mass spectra and elemental analysis. The chiral recognition of receptors was studied by 1H NMR and fluorescence spectra. The results demonstrate that receptors and dibenzoyl tartrate anion formed a 1:1 complex. The receptor 1 exhibited a good enantioselective recognition ability toward the enantiomers of dibenzoyl tartrate anion.
Calculation of Nuclear Spin Relaxation Times
Authors: L. Sudmeier James , E. Anderson Stanley , S. Frye James 
Published: March 2007

AbstractThis paper summarizes the equations for calculating nuclear spin relaxation times and nuclear Overhauser effects. The relaxation equations deal with the dipolar, quadrupolar, scalar, chemical shift anisotropy, paramagnetic, and spin‐rotation mechanisms for the simplest case of isotropic reorientation of rigid molecules. All equations are defined using consistent units, showing the similarities among various terms and giving numerical examples.
The use of freely diffusible, NMR‐detectable tracers for measuring organ perfusion
Authors: Neil Jeffrey J. 
Published: March 2007

AbstractThe application of NMR techniques to tracer methods for measuring organ perfusion is a relatively recent development. The general theory for measurement of organ perfusion after the administration of exogenous, freely diffusible tracers is discussed with special attention to NMR‐detectable tracers. Different routes of tracer administration are available and are presented in the context of the effect of route of administration on data analysis. A review of the recent literature validating the use of deuterium and fluorine as NMR flow tracers is provided.
Nuclear magnetic resonance measurements of intracellular pH: Biomedical implications
Authors: Malhotra Deepak , Shapiro Joseph I. 
Published: March 2007

AbstractThe measurement of intracellular pH is of crucial importance in biomedical investigation. Nuclear magnetic resonance (NMR) spectroscopy methods allow investigators to monitor this essential parameter in a variety of experimental conditions. Although a number of NMR spectroscopy methods for measuring intracellular pH have been described, the method of using the chemical shift of inorganic phosphate has been employed most widely. In this review, we discuss the various NMR methodologies which allow for measurement of intracellular pH as well as selected topics where these measurements have been employed. Because of the volume of work which has been published using NMR to monitor intracellular pH, we have not attempted to be exhaustive in our review, but rather have tried to highlight the importance of this methodology by reviewing several topics in biology and medicine where NMR measurements of intracellular pH have played an important role in improving our understanding.