bluuebunny/crossref_metadata_2025 huggingface dataset:
Uranium Monosulfide. I. Vaporization, Thermodynamics, and Phase Behavior
Authors: Cater E. David , Gilles Paul W. , Thorn R. J.
Published: July 2004

The rate of evaporation of uranium monosulfide has been measured over the 900-deg temperature range 1840° to 2730°K and a pressure range 10—3 to 10—8 atm, with an estimated accuracy of ±4%, by collection of vapor effusing from tungsten effusion cells containing the solid. The congruently evaporating composition was shown to be S/U=1.00. The effusion rate is expressed in terms of an ``effective'' vapor pressure PE calculated as though the entire vapor consisted of gaseous US molecules. An empirical equation derived by the method of least squares from the data is logPE(atm)=−1.7382+3.127×104/T−1.3181×108/T2+0.093776×1012/T3.Mass spectrometric measurements [E. D. Cater, E. G. Rauh, and R. J. Thorn, J. Chem. Phys. 35, 619 (1961)] show that the vaporization actually occurs both to gaseous US and to gaseous U+S. The present data are treated to yield the heats of sublimation at 2300°K to gaseous molecules, 150.3±2.1, and to gaseous elements, 271.2±4.0 kcal/mole, where the quoted uncertainties are estimated errors. The corresponding entropies of sublimation are: to molecules, 38.4±0.6, and to atoms, 65.5±1.6 cal/degmole. The lattice parameter of uranium monosulfide is 5.4903±0.0002 A. The melting point is 2735+30–5°K. The monosulfide solid phase appears to encompass a small composition range. Values derived from the experimental data and the literature for absolute entropies at 2300°K are 45±2 eu for solid, and 83±3 eu for gaseous US, where estimated errors are given. The heat of formation of solid US at 298°K from the gaseous atoms is estimated to be —273±5 kcal/mole and from the solid elements, —90±5. The free energies of formation of solid and gaseous monosulfide between 2100 and 2400°K are expressed by the equations ΔFf∘(US,s)=64.0T−268000cal/moleΔFf∘(US,g)=38.8T−152000cal/mole

A semitheoretical treatment gives nonlinear equations for the temperature dependences of the free energies and entropies of vaporization.
Dipole Moments of α,ω-Dibromoparaffins and Their Temperature Dependence
Authors: Hayman H. J. G. , Eliezer I.
Published: July 2004

The dipole moments of the eight α,ω-dibromoparaffins from dibromopropane to dibromodecane together with those of n-propyl and n-butyl bromide have been determined at 25° and 64°C in benzene solution. The results obtained are in good quantitative agreement with the theory developed previously on the assumption that the flexibility of these molecules is due to independent restricted rotations about the various C–C bonds. The data obtained were insufficient for determining the form of the potential barriers restricting these rotations, but could be interpreted in terms of the usual picture of gauche-trans rotational isomerism on the assumption that the energy of a gauche isomer is 0.40±0.12 kcal/mole more than that of the corresponding trans isomer, except for the rotations of the CH2Br groups when the energy difference is somewhat less, 0.34±0.14 kcal/mole.
Effect of Relaxation of Chemical Energy on the Thermal Conductivity of the System N2O4⇌2NO2
Authors: Srivastava B. N. , Barua A. K.
Published: July 2004

Franck and Spalthoff's treatment has been applied to interpret our thermal conductivity data for the system N2O4⇌2NO2. The results are satisfactory in view of the several simplifying assumptions in the treatment, when the chemical accommodation coefficient is also considered. It is seen that the none too satisfactory results obtained previously by Coffin when applying Franck and Spalthoff's treatment to this system are mainly due to the neglect of the chemical accommodation coefficient.
d-Hybridization of the Pi Bond in the 2pπu State of H2+
Authors: Sovers Ojars , Kauzmann Walter
Published: July 2004

LCAO—MO calculations have been made for the 2pπu state of H2+. Trial wave functions have been constructed which involve dπ orbitals as well as pπ orbitals about the two nuclei, and the energy has been computed for internuclear distances between 2 and 10 a.u. The discrepancies between these energies and the exact energies are decreased by as much as 87% as compared with the discrepancies obtained on using p orbitals alone. Inclusion of d orbitals also results in a considerable improvement in the equilibrium internuclear distance. The maximum ratio of the coefficients of the d orbitals to those of the p orbitals is about 0.24. The approximate wave functions have also been compared graphically with the exact solution.
Statistics of Orientation Effects in Linear Polymer Molecules
Authors: DiMarzio Edmund A.
Published: July 2004

This paper is concerned with the effects of orientation on the combinatorial term g for the number of ways to pack together Nx linear polymers (x mers). Accordingly g is evaluated as a function of the number of molecules in each permitted direction for the case of straight rigid rods. The permitted directions can be continuous so that g is derived as a function of the continuous function f(r) which gives the density of rods lying in the solid angle Δr, or the permitted directions can be discrete so that g is the number of ways to pack molecules onto a lattice. To illustrate the usefulness of the orientation dependent combinatorial terms, liquid crystals are discussed. Another phase is found to exist in addition to the previously predicted nematic phase. This phase is tentatively identified with the cholesteric phase.

A procedure is developed for the calculation of the orientation dependent combinatorial term associated with the packing together of molecules of arbitrary shape. A very approximate application of this procedure results in an approximate expression for the combinatorial term which allows one to predict qualitatively the change in the entropy of packing as a function of stretch. It is found that the entropy of packing has the proper behavior to explain the initial deviation of the experimental stress-strain curve from the previous theoretical predictions.
Calculation of Depolarization Ratios, Anisotropies, and Average Dimensions of n-Alkanes
Authors: Smith Richard P. , Mortensen Earl M.
Published: July 2004

A general scheme is outlined for the calculation of the anisotropy of the polarizability and the depolarization ratio for alkane chains. Computed results are given for these quantities and also for the mean-square end-end distance and the mean-square radius, for chains of up to 10 carbon atoms. The effects of various weighting-factor approximations, of excluded volume, of temperature, and of trans-gauche energy difference are discussed. The theoretical and experimental depolarization ratios are compared and discussed.
Effect of Electronegativity and Magnetic Anisotropy of Substituents on C13 and H1 Chemical Shifts in CH3X and CH3CH2X Compounds
Authors: Spiesecke H. , Schneider W. G.
Published: July 2004

An investigation has been made of the major contributions which make up the relative chemical shifts in CH3X and CH3CH2X compounds. In order to obtain more detailed information, both the carbon and hydrogen chemical shifts were measured. The carbon shifts were obtained by measuring natural abundance C13 resonances in the pure liquids; the H1 resonances were measured on gaseous samples to avoid solvent effects. The results reveal surprisingly large contributions to both C13 and H1 shifts arising from magnetic anisotropy effects of the X substituent. In CH3X compounds, the contribution to the proton shifts is negative while that to the C13 shifts is positive. In CH3CH2X compounds, these effects contribute to the resonance shifts of carbon and hydrogen nuclei in both the methylene and methyl group. When such contributions are allowed for, an approximate correlation with the electronegativity of X can be obtained, indicating that inductive effects, together with anisotropy effects, account for the major part of the relative chemical shifts in these molecules. The quantitative determination of inductive parameters of substituents from chemical shift data is, however, somewhat limited. The presence of a large magnetic anisotropy within the molecule also affects the nuclear resonance shifts of neighboring molecules and gives rise to a ``solvent dilution shift''; for the C13 resonance of CH3I this amounts to 7.3 ppm.
Raman Spectra and Ionic Interactions in Molten Nitrates
Authors: Janz George J. , James David W.
Published: July 2004

A simple experimental assembly designed for use with a conventional Toronto-type source and capable of use at temperatures up to 700°C is described for the Raman technique. Application to the series of molten inorganic salts Li, Na, K, Cs, Rb, and Ag/NO3, and selected mixtures of these, is reported. The Raman frequencies, relative intensities, depolarization ratios, and vibrational force constants are discussed. A regular variation of the Raman frequencies and force constants which correlates with the change in the polarizing power of the cationic environment is noted. The results are examined in the light of current views on the structure of molten salts.
Membrane lipid patterns typify distinct anaerobic methanotrophic consortia
Authors: Blumenberg Martin , Seifert Richard , Reitner Joachim , Pape Thomas , Michaelis Walter
Published: July 2004

The anaerobic oxidation of methane (AOM) is one of the major sinks of this substantial greenhouse gas in marine environments. Recent investigations have shown that diverse communities of anaerobic archaea and sulfate-reducing bacteria are involved in AOM. Most of the relevant archaea are assigned to two distinct phylogenetic clusters, ANME-1 and ANME-2. A suite of specific
13
C-depleted lipids demonstrating the presence of consortia mediating AOM in fossil and recent environments has been established. Here we report on substantial differences in the lipid composition of microbial consortia sampled from distinct compartments of AOM-driven carbonate reefs growing in the northwestern Black Sea. Communities in which the dominant archaea are from the ANME-1 cluster yield internally cyclized tetraether lipids typical of thermophiles. Those in which ANME-2 archaea are dominant yield
sn
-2-hydroxyarchaeol accompanied by crocetane and crocetenes. The bacterial lipids from these communities are also distinct even though the sulfate-reducing bacteria all belong to the
Desulfosarcina
/
Desulfococcus
group. Nonisoprenoidal glycerol diethers are predominantly associated with ANME-1-dominated communities. Communities with ANME-2 yield mainly conventional, ester-linked diglycerides. ANME-1 archaea and associated sulfate-reducing bacteria seem to be enabled to use low concentrations of methane and to grow within a broad range of temperatures. Our results offer a tool for the study of recent and especially of fossil methane environments.
Small-molecule-based identification of dynamic assembly of E2F–pocket protein–histone deacetylase complex for telomerase regulation in human cells
Authors: Won Jaejoon , Chang Seungwoo , Oh Sangtaek , Kim Tae Kook
Published: July 2004

Activation of telomerase is crucial for cells to gain immortality. Most normal human somatic cells have a limited proliferative life span, and expression of the rate-limiting telomerase catalytic subunit, known as human telomerase reverse transcriptase (hTERT), has been believed to be tightly repressed. This model of hTERT regulation is challenged by the recent identification of the induction of hTERT in normal cycling human fibroblasts during their transit through S phase. Here we show the small-molecule-based identification of the assembly and disassembly of E2F–pocket protein–histone deacetylase (HDAC) complex as a key mechanistic basis for the repression and activation of hTERT in normal human cells. A cell-based chemical screen was used to identify a small molecule, CGK1026, that derepresses hTERT expression. CGK1026 inhibits the recruitment of HDAC into E2F–pocket protein complexes assembled on the hTERT promoter. Chromatin immunoprecipitation analysis reveals dynamic alterations in hTERT promoter occupancy by E2F and pocket proteins according to the cell cycle-dependent regulation of hTERT. Dominant-negative or protein-knockout strategies to disrupt the assembly of E2F–pocket protein–HDAC complex derepress hTERT and telomerase activity. Taken together with the results on the regulatory function of these complexes in cellular senescence and tumorigenesis, our findings suggest that dynamic assembly of E2F–pocket protein–HDAC complex plays a central role in the regulation of hTERT in a variety of proliferative conditions (e.g., normal cycling, senescent, and tumor cells).
Recombinant poxvirus boosting of DNA-primed rhesus monkeys augments peak but not memory T lymphocyte responses
Authors: Santra Sampa , Barouch Dan H. , Korioth-Schmitz Birgit , Lord Carol I. , Krivulka Georgia R. , Yu Faye , Beddall Margaret H. , Gorgone Darci A. , Lifton Michelle A. , Miura Ayako , Philippon Valerie , Manson Kelledy , Markham Phillip D. , Parrish John , Kuroda Marcelo J. , Schmitz Jörn E. , Gelman Rebecca S. , Shiver John W. , Montefiori David C. , Panicali Dennis , Letvin Norman L.
Published: July 2004

Although a consensus has emerged that an HIV vaccine should elicit a cytotoxic T lymphocyte (CTL) response, the characteristics of an effective vaccine-induced T lymphocyte response remain unclear. We explored this issue in the simian human immunodeficiency virus/rhesus monkey model in the course of assessing the relative immunogenicity of vaccine regimens that included a cytokine-augmented plasmid DNA prime and a boost with DNA or recombinant pox vectors. Recombinant vaccinia virus, recombinant modified vaccinia Ankara (MVA), and recombinant fowlpox were comparable in their immunogenicity. Moreover, whereas the magnitude of the peak vaccine-elicited T lymphocyte responses in the recombinant pox virus-boosted monkeys was substantially greater than that seen in the monkeys immunized with plasmid DNA alone, the magnitudes of recombinant pox boosted CTL responses decayed rapidly and were comparable to those of the DNA-alone-vaccinated monkeys by the time of viral challenge. Consistent with these comparable memory T cell responses, the clinical protection seen in all groups of experimentally vaccinated monkeys was similar. This study, therefore, indicates that the steady-state memory, rather than the peak effector vaccine-elicited T lymphocyte responses, may be the critical immune correlate of protection for a CTL-based HIV vaccine.
Evidence for defective energy homeostasis in amyotrophic lateral sclerosis: Benefit of a high-energy diet in a transgenic mouse model
Authors: Dupuis Luc , Oudart Hugues , René Frédérique , de Aguilar Jose-Luis Gonzalez , Loeffler Jean-Philippe
Published: July 2004

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterized by selective loss of motor neurons and progressive muscle wasting. Growing evidence indicates that mitochondrial dysfunction, not only occurring in motor neurons but also in skeletal muscle, may play a crucial role in the pathogenesis. In this regard, the life expectancy of the ALS G93A mouse line is extended by creatine, an intracellular energy shuttle that ameliorates muscle function. Moreover, a population of patients with sporadic ALS exhibits a generalized hypermetabolic state of as yet unknown origin. Altogether, these findings led us to explore whether alterations in energy homeostasis may contribute to the disease process. Here, we show important variations in a number of metabolic indicators in transgenic ALS mice, which in all shows a metabolic deficit. These alterations were accompanied early in the asymptomatic phase of the disease by reduced adipose tissue accumulation, increased energy expenditure, and concomitant skeletal muscle hypermetabolism. Compensating this energetic imbalance with a highly energetic diet extended mean survival by 20%. In conclusion, we suggest that hypermetabolism, mainly of muscular origin, may represent by itself an additional driven force involved in increasing motor neuron vulnerability.
Effects of dietary omega-3 polyunsaturated fatty acids on brain gene expression
Authors: Kitajka Klára , Sinclair Andrew J. , Weisinger Richard S. , Weisinger Harrison S. , Mathai Michael , Jayasooriya Anura P. , Halver John E. , Puskás László G.
Published: July 2004

Polyunsaturated fatty acids (PUFA) are essential structural components of the central nervous system. Their role in controlling learning and memory has been well documented. A nutrigenomic approach with high-density microarrays was used to reveal brain gene-expression changes in response to different PUFA-enriched diets in rats. In aged rats fed throughout life with PUFA-enriched diets, genes with altered expressions included transthyretin, α-synuclein, and calmodulins, which play important roles in synaptic plasticity and learning. The effect of perinatal omega-3 PUFA supply on gene expression later in life also was studied. Several genes showed similar changes in expression in rats fed omega-3-deficient diets in the perinatal period, regardless of whether they or their mothers were fed omega-3 PUFA-sufficient diets after giving birth. In this experiment, among the down-regulated genes were a kainate glutamate receptor and a DEAD-box polypeptide. Among the up-regulated genes were a chemokine-like factor, a tumor necrosis factor receptor, and cytochromec. The possible involvement of the genes with altered expression attributable to different diets in different brain regions in young and aged rats and the possible mode of regulatory action of PUFA also are discussed. We conclude that PUFA-enriched diets lead to significant changes in expression of several genes in the central nervous tissue, and these effects appear to be mainly independent of their effects on membrane composition. The direct effects of PUFA on transcriptional modulators, the downstream developmentally and tissue-specifically activated elements might be one of the clues to understanding the beneficial effects of the omega-3 PUFA on the nervous system.
Noninactivating voltage-gated sodium channels in severe myoclonic epilepsy of infancy
Authors: Rhodes Thomas H. , Lossin Christoph , Vanoye Carlos G. , Wang Dao W. , George Alfred L.
Published: July 2004

Mutations in
SCN1A
, the gene encoding the brain voltage-gated sodium channel α
1
subunit (Na
V
1.1), are associated with at least two forms of epilepsy, generalized epilepsy with febrile seizures plus and severe myoclonic epilepsy of infancy (SMEI). We examined the functional properties of five SMEI mutations by using whole-cell patch-clamp analysis of heterologously expressed recombinant human SCN1A. Two mutations (F902C and G1674R) rendered SCN1A channels nonfunctional, and a third allele (G1749E) exhibited minimal functional alterations. However, two mutations within or near the S4 segment of the fourth repeat domain (R1648C and F1661S) conferred significant impairments in fast inactivation, including persistent, noninactivating channel activity resembling the pattern of channel dysfunction observed for alleles associated with generalized epilepsy with febrile seizures plus. Our data provide evidence for a range of SCN1A functional abnormalities in SMEI, including gain-of-function defects that were not anticipated in this disorder. Our results further indicate that a complex relationship exists between phenotype and aberrant sodium channel function in these inherited epilepsies.
Pre-B cell receptor expression is necessary for thymic stromal lymphopoietin responsiveness in the bone marrow but not in the liver environment
Authors: Vosshenrich Christian A. J. , Cumano Ana , Müller Werner , Di Santo James P. , Vieira Paulo
Published: July 2004

IL-7 and thymic stromal lymphopoietin (TSLP) are two major cytokines controlling murine B cell development. IL-7 has been studied extensively, but only recently has it become possible to unravel the role of TSLP in detail. We studied the biological activities of TSLP in B cell development at distinct ages in the mouse. On the one hand, TSLP is able to give rise to a measurable B1 cell compartment derived from fetal liver pro-B cells, although, as is the case for B2 cells, it does not play a prevalent role in the development of this subset. On the other hand, TSLP drives the proliferation of pro-B cells from the fetal and neonatal liver, but in the bone marrow environment, B cell precursors require pre-B cell receptor expression for TSLP responsiveness.
Exocytosis of IgG as mediated by the receptor, FcRn: An analysis at the single-molecule level
Authors: Ober Raimund J. , Martinez Cruz , Lai Xuming , Zhou Jinchun , Ward E. Sally
Published: July 2004

IgG transport within and across cells is essential for effective humoral immunity. Through a combination of biochemical andin vivoanalyses, the MHC class I-related neonatal Fc receptor (FcRn) is known to play a central role in delivering IgGs within and across cells. However, little is known about the molecular and cellular mechanisms that are involved in the exocytosis of IgG from cells that express FcRn. Here, we use single-molecule fluorescence microscopy to analyze exocytic processes in FcRn-GFP-transfected human endothelial cells. We show that exocytosis can occur by means of multiple modes that range from complete fusion of the exocytic vesicle with the plasma membrane to a slower-release mode (“prolonged release”) that only involves partial mixing of membrane contents. Even for prolonged release, diffusion of FcRn into the plasma membrane can occur, indicating that FcRn is directly involved in IgG exocytosis. The slower-release mode is characterized by periodic, stepwise release of IgG, rather than the rapid burst that is observed for complete-fusion events. Analyses of single-molecule tracks suggest that IgG may be bound to FcRn for several seconds after exocytosis. Unexpectedly, after diffusion out of the exocytic site, IgG and FcRn molecules can also migrate back into the epicenter of the release site. Such retrograde movement may represent a mechanism for FcRn retrieval. Our studies provide insight into the events that lead to IgG exocytosis.
Characterization of synthetic DNA bar codes in
Saccharomyces cerevisiae
gene-deletion strains
Authors: Eason Robert G. , Pourmand Nader , Tongprasit Waraporn , Herman Zelek S. , Anthony Kevin , Jejelowo Olufisayo , Davis Ronald W. , Stolc Viktor
Published: July 2004

Incorporation of strain-specific synthetic DNA tags into yeast
Saccharomyces cerevisiae
gene-deletion strains has enabled identification of gene functions by massively parallel growth rate analysis. However, it is important to confirm the sequences of these tags, because mutations introduced during construction could lead to significant errors in hybridization performance. To validate this experimental system, we sequenced 11,812 synthetic 20-mer molecular bar codes and adjacent sequences (>1.8 megabases synthetic DNA) by pyrosequencing and Sanger methods. At least 31% of the genome-integrated 20-mer tags contain differences from those originally synthesized. However, these mutations result in anomalous hybridization in only a small subset of strains, and the sequence information enables redesign of hybridization probes for arrays. The robust performance of the yeast gene-deletion dual oligonucleotide bar-code design in array hybridization validates the use of molecular bar codes in living cells for tracking their growth phenotype.
IL-2 and IL-15 receptor α-subunits are coexpressed in a supramolecular receptor cluster in lipid rafts of T cells
Authors: Vámosi György , Bodnár Andrea , Vereb György , Jenei Attila , Goldman Carolyn K. , Langowski Jörg , Tóth Katalin , Mátyus László , Szöllösi János , Waldmann Thomas A. , Damjanovich Sándor
Published: July 2004

The private α-chains of IL-2 and IL-15 receptors (IL-2R and IL-15R) share the signaling β- and γc-subunits, resulting in both common and contrasting roles of IL-2 and IL-15 in T cell function. Knowledge of the cytokine-dependent subunit assembly is indispensable for understanding the paradox of distinct signaling capacities. By using fluorescence resonance energy transfer and confocal microscopy, we have shown that IL-2Rα, IL-15Rα, IL-2/15Rβ and γc-subunits, as well as MHC class I and II glycoproteins formed supramolecular receptor clusters in lipid rafts of the T lymphoma line Kit 225 FT7.10. Fluorescence crosscorrelation microscopy demonstrated the comobility of IL-15Rα with IL-2Rα and MHC class I. A model was generated for subunit switching between IL-2Rα and IL-15Rα upon the binding of the appropriate cytokine resulting in the formation of high-affinity heterotrimeric receptors. This model suggests a direct role for the α-subunits, to which no definite function has been assigned so far, in tuning cellular responses to IL-2 or IL-15. In addition, both α-chains were at least partially homodimerized/oligomerized, which could be the basis of distinct signaling pathways by the two cytokines.
Genomic DNA double-strand breaks are targets for hepadnaviral DNA integration
Authors: Bill Colin A. , Summers Jesse
Published: July 2004

Integrated hepadnaviral DNA in livers and tumors of chronic hepatitis B patients has been reported for many years. In this study, we investigated whether hepatitis B virus DNA integration occurs preferentially at sites of cell DNA damage. A single I-SceI homing endonuclease recognition site was introduced into the DNA of the chicken hepatoma cell line LMH by stable DNA transfection, and double-strand breaks were induced by transient expression of I-SceI after transfection of an I-SceI expression vector. Alteration of the target cleavage site by imprecise nonhomologous end joining occurred at a frequency of ≈10–3per transfected cell. When replication of an avian hepadnavirus, duck hepatitis B virus, occurred at the time of double-strand break repair, we observed integration of viral DNA at the site of the break with a frequency of ≈10–4per transfected cell. Integration depended on the production of viral double-stranded linear DNA and the expression of I-SceI, and integrated DNA was stable through at least 17 cell divisions. Integration appeared to occur through nonhomologous end joining between the viral linear DNA ends and the I-SceI-induced break, because small deletions or insertions were observed at the sites of end joining. The results suggest that integration of hepadnaviral DNA in infected livers occurs at sites of DNA damage and may indicate the presence of more widespread genetic changes caused by viral DNA integration itself.
Acetaminophen-induced hypothermia in mice is mediated by a prostaglandin endoperoxide synthase 1 gene-derived protein
Authors: Ayoub Samir S. , Botting Regina M. , Goorha Sarita , Colville-Nash Paul R. , Willoughby Derek A. , Ballou Leslie R.
Published: July 2004

Acetaminophen is a widely used antipyretic analgesic, reducing fever caused by bacterial and viral infections and by clinical trauma such as cancer or stroke. In rare cases in humans, e.g., in febrile children or HIV or stroke patients, acetaminophen causes hypothermia while therapeutic blood levels of the drug are maintained. In C57/BL6 mice, acetaminophen caused hypothermia that was dose related and maximum (>2°C below normal) with a dose of 300 mg/kg. The reduction and recovery of body temperature was paralleled by a fall of >90% and a subsequent rise of prostaglandin (PG)E
2
concentrations in the brain. In cyclooxygenase (COX)-2
–/–
mice, acetaminophen (300 mg/kg) produced hypothermia accompanied by a reduction in brain PGE
2
levels, whereas in COX-1
–/–
mice, the hypothermia to this dose of acetaminophen was attenuated. The brains of COX-1
–/–
mice had ≈70% lower levels of PGE
2
than those of WT animals, and these levels were not reduced further by acetaminophen. The putative selective COX-3 inhibitors antipyrine and aminopyrine also reduced basal body temperature and brain PGE
2
levels in normal mice. We propose that acetaminophen is a selective inhibitor of a COX-1 variant and this enzyme is involved in the continual synthesis of PGE
2
that maintains a normal body temperature. Thus, acetaminophen reduces basal body temperature below normal in mice most likely by inhibiting COX-3.
Prospects for inferring very large phylogenies by using the neighbor-joining method
Authors: Tamura Koichiro , Nei Masatoshi , Kumar Sudhir
Published: July 2004

Current efforts to reconstruct the tree of life and histories of multigene families demand the inference of phylogenies consisting of thousands of gene sequences. However, for such large data sets even a moderate exploration of the tree space needed to identify the optimal tree is virtually impossible. For these cases the neighbor-joining (NJ) method is frequently used because of its demonstrated accuracy for smaller data sets and its computational speed. As data sets grow, however, the fraction of the tree space examined by the NJ algorithm becomes minuscule. Here, we report the results of our computer simulation for examining the accuracy of NJ trees for inferring very large phylogenies. First we present a likelihood method for the simultaneous estimation of all pairwise distances by using biologically realistic models of nucleotide substitution. Use of this method corrects up to 60% of NJ tree errors. Our simulation results show that the accuracy of NJ trees decline only by ≈5% when the number of sequences used increases from 32 to 4,096 (128 times) even in the presence of extensive variation in the evolutionary rate among lineages or significant biases in the nucleotide composition and transition/transversion ratio. Our results encourage the use of complex models of nucleotide substitution for estimating evolutionary distances and hint at bright prospects for the application of the NJ and related methods in inferring large phylogenies.
Selective inhibition of the citrate-to-isocitrate reaction of cytosolic aconitase by phosphomimetic mutation of serine-711
Authors: Pitula Joseph S. , Deck Kathryn M. , Clarke Stephen L. , Anderson Sheila A. , Vasanthakumar Aparna , Eisenstein Richard S.
Published: July 2004

Iron-regulatory protein 1 (IRP1) is a dual-function protein with mutually exclusive roles as a posttranscriptional regulator of animal-cell iron metabolism or as the cytosolic isoform of the iron–sulfur enzyme aconitase (c-acon). Much effort has focused on the role of IRP1 in posttranscriptional gene regulation and in factors that influence its interconversion with c-acon, but little is known about the metabolic function and regulation of c-acon. The role of PKC-dependent phosphorylation of S711 on IRP1/c-acon function was examined. Phosphorylation state-specific antibodies revealed that S711 is phosphorylated by PKC
in vitro
and in human embryonic kidney cells treated with a PKC activator. In
aco1
yeast, the phosphomimetic mutants S711D and S711E exhibited severely impaired aconitase function, whereas S711A and S711T were unaffected relative to the WT protein. Aconitase activity in yeast extracts displayed a similar pattern when assayed for capacity to convert citrate to isocitrate: WT, S711A, and S711T were active, but S711D and S711E activity was undetectable. In contrast, when measured by the conversion of isocitrate to
cis
-aconitate, S711D and S711E displayed substantial activity, indicating that phosphorylation impairs the citrate but not isocitrate mode of aconitase function. This possibility was confirmed
in vivo
by demonstrating that S711D and S711E specifically antagonized the requirement for isocitrate in two metabolic scenarios. Iron-responsive element RNA-binding affinity was unaffected by S711 mutations. Our results show that S711 is a target of phosphorylation capable of conferring distinct effects on c-acon function potentially dictating changes in cytosolic citrate/isocitrate metabolism.
Southern Peru desert shattered by the great 2001 earthquake: Implications for paleoseismic and paleo-El Niño–Southern Oscillation records
Authors: Keefer David K. , Moseley Michael E.
Published: July 2004

In the desert region around the coastal city of Ilo, the great southern Peru earthquake of June 23, 2001 (8.2–8.4 moment magnitude), produced intense and widespread ground-failure effects. These effects included abundant landslides, pervasive ground cracking, microfracturing of surficial hillslope materials, collapse of drainage banks over long stretches, widening of hillside rills, and lengthening of first-order tributary channels. We have coined the term “shattered landscape” to describe the severity of these effects. Long-term consequences of this landscape shattering are inferred to include increased runoff and sediment transport during postearthquake rainstorms. This inference was confirmed during the first minor postearthquake rainstorm there, which occurred in June and July of 2002. Greater amounts of rainfall in this desert region have historically been associated with El Niño events. Previous studies of an unusual paleoflood deposit in this region have concluded that it is the product of El Niño-generated precipitation falling on seismically disturbed landscapes. The effects of the 2001 earthquake and 2002 rainstorm support that conclusion.
Early exit from the labour market through the unemployment pathway in Finland
Authors: Hytti Helka
Published: July 2004

The focus of the study is on patterns of early exit from the labour market in Finland with a special emphasis on the unemployment pathway. The period under review extends from the early 1980s to the turn of the century. The data for the study were obtained from individual-level files formed by combining census data with statistical registries of social security. The study takes a comparative macro-level approach, with comparisons being made between different periods of time. The results are interpreted from the point of view of the connection between early exit, increasing economic openness and structural change in society. In the 1980s, utilization of the unemployment pathway in a given branch depended primarily on how open the branch was to international competition. In the deep economic recession of the 1990s rate of exit was highest in the branches with primarily a domestic focus, which were hardest hit by the recession. The exit rates were remarkably high also in the previously public-sector branches recently opened to competition. After the recession, in 1996–1998, adjustments to international competition seemed to explain a great deal of early exit behaviour. From a broader European perspective the Finnish unemployment pathway, combining economic competitiveness and social cohesion, can be seen as an example of the workability of the European social model. The capability of Finnish early exit policy for adjustment in the face of changing societal and international pressures was further proved in November 2001, when a broad-based agreement on changes in early exit and old age pension schemes was achieved by the labour market partners in line with general objectives put forward by the Government.
Starting the first family
Authors: Oinonen Eriikka
Published: July 2004

In Finland and Spain, marriage rates are equally low, yet cohabitation is rare in Spain and common in Finland. The fertility rate has fallen sharply in Spain, whereas in Finland it is relatively high. Spaniards delay childbearing later than Finns. These characteristics of family formation are not attributed to modern contraceptives, cohabitation or to the female employment rate. Neither women's labour market position nor family policy is the key explanatory factor for the differences in patterns of first family formation and fertility. However, the employment and financial insecurity of young people seem to be an influential factor having negative effects on the first family formation in Finland and Spain.
The Effect of Water, Sugars, and Proteins on the Pattern of Ice Nucleation and Propagation in Acclimated and Nonacclimated Canola Leaves
Authors: Gusta L.V. , Wisniewski M. , Nesbitt N.T. , Gusta M.L.
Published: July 2004

Infrared video thermography was used to observe ice nucleation temperatures, patterns of ice formation, and freezing rates in nonacclimated and cold acclimated leaves of a spring (cv Quest) and a winter (cv Express) canola (Brassica napus). Distinctly different freezing patterns were observed, and the effect of water content, sugars, and soluble proteins on the freezing process was characterized. When freezing was initiated at a warm subzero temperature, ice growth rapidly spread throughout nonacclimated leaves. In contrast, acclimated leaves initiated freezing in a horseshoe pattern beginning at the uppermost edge followed by a slow progression of ice formation across the leaf. However, when acclimated leaves, either previously killed by a slow freeze (2°C h−1) or by direct submersion in liquid nitrogen, were refrozen their freezing pattern was similar to nonacclimated leaves. A novel technique was developed using filter paper strips to determine the effects of both sugars and proteins on the rate of freezing of cell extracts. Cell sap from nonacclimated leaves froze 3-fold faster than extracts from acclimated leaves. The rate of freezing in leaves was strongly dependent upon the osmotic potential of the leaves. Simple sugars had a much greater effect on freezing rate than proteins. Nonacclimated leaves containing high water content did not supercool as much as acclimated leaves. Additionally, wetted leaves did not supercool as much as nonwetted leaves. As expected, cell solutes depressed the nucleation temperature of leaves. The use of infrared thermography has revealed that the freezing process in plants is a complex process, reminding us that many aspects of freezing tolerance occur at a whole plant level involving aspects of plant structure and metabolites rather than just the expression of specific genes alone.
Proline Betaine Accumulation and Metabolism in Alfalfa Plants under Sodium Chloride Stress. Exploring Its Compartmentalization in Nodules
Authors: Trinchant Jean-Charles , Boscari Alexandre , Spennato Guillaume , Van de Sype Ghislaine , Le Rudulier Daniel
Published: July 2004

The osmoprotectant Pro betaine is the main betaine identified in alfalfa (Medicago sativa). We have investigated the long-term responses of nodulated alfalfa plants to salt stress, with a particular interest for Pro betaine accumulation, compartmentalization, and metabolism. Exposure of 3-week-old nodulated alfalfa plants to 0.2 m NaCl for 4 weeks was followed by a 10-, 4-, and 8-fold increase in Pro betaine in shoots, roots, and nodules, respectively. Isotope-labeling studies in alfalfa shoots indicate that [14C]Pro betaine was synthesized from l-[14C]Pro. [14C]Pro betaine was efficiently catabolized through sequential demethylations via N-methylPro and Pro. Salt stress had a minor effect on Pro betaine biosynthesis, whereas it strongly reduced Pro betaine turnover. Analysis of Pro betaine and Pro compartmentalization within nodules revealed that 4 weeks of salinization of the host plants induced a strong increase in cytosol and bacteroids. The estimated Pro betaine and Pro concentrations in salt-stressed bacteroids reached 7.4 and 11.8 mm, respectively, compared to only 0.8 mm in control bacteroids. Na+ content in nodule compartments was also enhanced under salinization, leading to a concentration of 14.7 mm in bacteroids. [14C]Pro betaine and [14C]Pro were taken up by purified symbiosomes and free bacteroids. There was no indication of saturable carrier(s), and the rate of uptake was moderately enhanced by salinization. Ultrastructural analysis showed a large peribacteroid space in salt-stressed nodules, suggesting an increased turgor pressure inside the symbiosomes, which might partially be due to an elevated concentration in Pro, Pro betaine, and Na+ in this compartment.
The Innate Immunity of a Marine Red Alga Involves Oxylipins from Both the Eicosanoid and Octadecanoid Pathways
Authors: Bouarab Kamal , Adas Fadi , Gaquerel Emmanuel , Kloareg Bernard , Salaün Jean-Pierre , Potin Philippe
Published: July 2004

The oxygenated derivatives of fatty acids, known as oxylipins, are pivotal signaling molecules in animals and terrestrial plants. In animal systems, eicosanoids regulate cell differentiation, immune responses, and homeostasis. In contrast, terrestrial plants use derivatives of C18 and C16 fatty acids as developmental or defense hormones. Marine algae have emerged early in the evolution of eukaryotes as several distinct phyla, independent from the animal and green-plant lineages. The occurrence of oxylipins of the eicosanoid family is well documented in marine red algae, but their biological roles remain an enigma. Here we address the hypothesis that they are involved with the defense mechanisms of the red alga Chondrus crispus. By investigating its association with a green algal endophyte Acrochaete operculata, which becomes invasive in the diploid generation of this red alga, we showed that (1) when challenged by pathogen extracts, the resistant haploid phase of C. crispus produced both C20 and C18 oxylipins, (2) elicitation with pathogen extracts or methyl jasmonate activated the metabolism of C20 and C18 polyunsaturated fatty acids to generate hydroperoxides and cyclopentenones such as prostaglandins and jasmonates, and (3) C20 and C18 hydroperoxides as well as methyl jasmonate did induce shikimate dehydrogenase and Phe ammonialyase activities in C. crispus and conferred an induced resistance to the diploid phase, while inhibitors of fatty acid oxidation reduced the natural resistance of the haploid generation. The dual nature of oxylipin metabolism in this alga suggests that early eukaryotes featured both animal- (eicosanoids) and plant-like (octadecanoids) oxylipins as essential components of innate immunity mechanisms.
Development of Genome-Wide DNA Polymorphism Database for Map-Based Cloning of Rice Genes
Authors: Shen Ying-Jia , Jiang Hua , Jin Jian-Peng , Zhang Zai-Bao , Xi Biao , He You-Yu , Wang Guan , Wang Chen , Qian Lily , Li Xiang , Yu Qing-Bo , Liu Hui-Juan , Chen De-Hui , Gao Jian-Hua , Huang Hai , Shi Tie-Liu , Yang Zhong-Nan
Published: July 2004

DNA polymorphism is the basis to develop molecular markers that are widely used in genetic mapping today. A genome-wide rice (Oryza sativa) DNA polymorphism database has been constructed in this work using the genomes of Nipponbare, a cultivar of japonica, and 93-11, a cultivar of indica. This database contains 1,703,176 single nucleotide polymorphisms (SNPs) and 479,406 Insertion/Deletions (InDels), approximately one SNP every 268 bp and one InDel every 953 bp in rice genome. Both SNPs and InDels in the database were experimentally validated. Of 109 randomly selected SNPs, 107 SNPs (98.2%) are accurate. PCR analysis indicated that 90% (97 of 108) of InDels in the database could be used as molecular markers, and 68% to 89% of the 97 InDel markers have polymorphisms between other indica cultivars (Guang-lu-ai 4 and Long-te-pu B) and japonica cultivars (Zhong-hua 11 and 9522). This suggests that this database can be used not only for Nipponbare and 93-11, but also for other japonica and indica cultivars. While validating InDel polymorphisms in the database, a set of InDel markers with each chromosome 3 to 5 marker was developed. These markers are inexpensive and easy to use, and can be used for any combination of japonica and indica cultivars used in this work. This rice DNA polymorphism database will be a valuable resource and important tool for map-based cloning of rice gene, as well as in other various research on rice (http://shenghuan.shnu.edu.cn/ricemarker).
Binding of Arabinogalactan Proteins by Yariv Phenylglycoside Triggers Wound-Like Responses in Arabidopsis Cell Cultures
Authors: Guan Yu , Nothnagel Eugene A.
Published: July 2004

Arabinogalactan-proteins (AGPs) are cell wall proteoglycans and are widely distributed in the plant kingdom. Classical AGPs and some nonclassical AGPs are predicted to have a glycosylphosphatidylinositol lipid anchor and have been suggested to be involved in cell-cell signaling. Yariv phenylglycoside is a synthetic probe that specifically binds to plant AGPs and has been used to study AGP functions. We treated Arabidopsis suspension cell cultures with Yariv phenylglycoside and observed decreased cell viability, increased cell wall apposition and cytoplasmic vesiculation, and induction of callose deposition. The induction of cell wall apposition and callose synthesis led us to hypothesize that Yariv binding of plant surface AGPs triggers wound-like responses. To study the effect of Yariv binding to plant surface AGPs and to further understand AGP functions, an Arabidopsis whole genome array was used to monitor the transcriptional modifications after Yariv treatment. By comparing the genes that are induced by Yariv treatment with genes whose expressions have been previously shown to be induced by other conditions, we conclude that the gene expression profile induced by Yariv phenylglycoside treatment is most similar to that of wound induction. It remains uncertain whether the Yariv phenylglycoside cross-linking of cell surface AGPs induces these genes through a specific AGP-based signaling mechanism or through a general mechanical perturbation of the cell surface.
A Novel Inhibitor of 9-cis-Epoxycarotenoid Dioxygenase in Abscisic Acid Biosynthesis in Higher Plants
Authors: Han Sun-Young , Kitahata Nobutaka , Sekimata Katsuhiko , Saito Tamio , Kobayashi Masatomo , Nakashima Kazuo , Yamaguchi-Shinozaki Kazuko , Shinozaki Kazuo , Yoshida Shigeo , Asami Tadao
Published: July 2004

Abscisic acid (ABA) is a major regulator in the adaptation of plants to environmental stresses, plant growth, and development. In higher plants, the ABA biosynthesis pathway involves the oxidative cleavage of 9-cis-epoxycarotenoids, which may be the key regulatory step in the pathway catalyzed by 9-cis-epoxycarotenoid dioxygenase (NCED). We developed a new inhibitor of ABA biosynthesis targeting NCED and named it abamine (ABA biosynthesis inhibitor with an amine moiety). Abamine is a competitive inhibitor of NCED, with a K  i of 38.8 μ  m. In 0.4 m mannitol solution, which mimics the effects of osmotic stress, abamine both inhibited stomatal closure in spinach (Spinacia oleracea) leaves, which was restored by coapplication of ABA, and increased luminescence intensity in transgenic Arabidopsis containing the RD29B promoter-luciferase fusion. The ABA content of plants in 0.4 m mannitol was increased approximately 16-fold as compared with that of controls, whereas 50 to 100 μ  m abamine inhibited about 50% of this ABA accumulation in both spinach leaves and Arabidopsis. Abamine-treated Arabidopsis was more sensitive to drought stress and showed a significant decrease in drought tolerance than untreated Arabidopsis. These results suggest that abamine is a novel ABA biosynthesis inhibitor that targets the enzyme catalyzing oxidative cleavage of 9-cis-epoxycarotenoids. To test the effect of abamine on plants other than Arabidopsis, it was applied to cress (Lepidium sativum) plants. Abamine enhanced radicle elongation in cress seeds, which could be due to a decrease in the ABA content of abamine-treated plants. Thus, it is possible to think that abamine should enable us to elucidate the functions of ABA in cells or plants and to find new mutants involved in ABA signaling.