bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complete Cellulase System in the Marine BacteriumSaccharophagus degradansStrain 2-40T
Authors: Taylor Larry E. , Henrissat Bernard , Coutinho Pedro M. , Ekborg Nathan A. , Hutcheson Steven W. , Weiner Ronald M. 
Published: May 2006

ABSTRACTSaccharophagus degradansstrain 2-40 is a representative of an emerging group of marine complex polysaccharide (CP)-degrading bacteria. It is unique in its metabolic versatility, being able to degrade at least 10 distinct CPs from diverse algal, plant and invertebrate sources. TheS. degradansgenome has been sequenced to completion, and more than 180 open reading frames have been identified that encode carbohydrases. Over half of these are likely to act on plant cell wall polymers. In fact, there appears to be a full array of enzymes that degrade and metabolize plant cell walls. Genomic and proteomic analyses reveal 13 cellulose depolymerases complemented by seven accessory enzymes, including two cellodextrinases, three cellobiases, a cellodextrin phosphorylase, and a cellobiose phosphorylase. Most of these enzymes exhibit modular architecture, and some contain novel combinations of catalytic and/or substrate binding modules. This is exemplified by endoglucanase Cel5A, which has three internal family 6 carbohydrate binding modules (CBM6) and two catalytic modules from family five of glycosyl hydrolases (GH5) and by Cel6A, a nonreducing-end cellobiohydrolase from family GH6 with tandem CBM2s. This is the first report of a complete and functional cellulase system in a marine bacterium with a sequenced genome.
Ectopic Overexpression of Wild-Type and Mutant
hipA
Genes in
Escherichia coli
: Effects on Macromolecular Synthesis and Persister Formation
Authors: Korch Shaleen B. , Hill Thomas M. 
Published: May 2006

ABSTRACT

Persistence is an epigenetic trait that allows a small fraction of bacteria, approximately one in a million, to survive prolonged exposure to antibiotics. In
Escherichia coli
an increased frequency of persisters, called “high persistence,” is conferred by mutations in the
hipA
gene, which encodes the toxin entity of the toxin-antitoxin module
hipBA
. The high-persistence allele
hipA7
was originally identified because of its ability to confer high persistence, but little is known about the physiological role of the wild-type
hipA
gene. We report here that the expression of wild-type
hipA
in excess of
hipB
inhibits protein, RNA, and DNA synthesis in vivo. However, unlike the RelE and MazF toxins, HipA had no effect on protein synthesis in an in vitro translation system. Moreover, the expression of wild-type
hipA
conferred a transient dormant state (persistence) to a sizable fraction of cells, whereas the rest of the cells remained in a prolonged dormant state that, under appropriate conditions, could be fully reversed by expression of the cognate antitoxin gene
hipB
. In contrast, expression of the mutant
hipA7
gene in excess of
hipB
did not markedly inhibit protein synthesis as did wild-type
hipA
and yet still conferred persistence to ca. 10% of cells. We propose that wild-type HipA, upon release from HipB, is able to inhibit macromolecular synthesis and induces a bacteriostatic state that can be reversed by expression of the
hipB
gene. However, the ability of the wild-type
hipA
gene to generate a high frequency of persisters, equal to that conferred by the
hipA7
allele, may be distinct from the ability to block macromolecular synthesis.
Molecular Basis of
l
-Rhamnose Branch Formation in Streptococcal Coaggregation Receptor Polysaccharides
Authors: Yoshida Yasuo , Ganguly Soumya , Bush C. Allen , Cisar John O. 
Published: May 2006

ABSTRACT

The presence of
l
-rhamnose (Rha) branches in the coaggregation receptor polysaccharides (RPS) of
Streptococcus gordonii
38 and
Streptococcus oralis
J22 was eliminated by replacement of
wefB
with
ermAM
in these strains. The expression of this gene in
S. oralis
34 did not, however, result in the addition of Rha branches to the linear RPS of this strain, which is identical to that produced by the
wefB
-deficient mutant of
S. gordonii
38. This paradoxical finding was explained by a subtle difference in acceptor specificity of the galactose-1-phosphotransferases encoded by downstream
wefC
in
S. gordonii
38 and
wefH
in
S. oralis
34. These genes were distinguished by the unique ability of WefC to act on the branched acceptor formed by the action of WefB.
Evolution of Immunity and Host Chromosome Integration Site of P2-Like Coliphages
Authors: Karlsson Joakim L. , Cardoso-Palacios Carlos , Nilsson Anders S. , Haggård-Ljungquist Elisabeth 
Published: May 2006

ABSTRACT

The amount and distribution of variation in the genomic region containing the genes in the lytic-lysogenic genetic switch and the sequence that determines the integration site into the host chromosome were analyzed for 38 P2-like phages from
Escherichia coli
. The genetic switch consists of two convergent mutually exclusive promoters, Pe and Pc, and two repressors, C and Cox. The immunity repressor C blocks the early Pe promoter, leading to the establishment of lysogeny. The Cox repressor blocks expression of Pc, allowing lytic growth. Phylogenetic analyses showed that the C and Cox proteins were distributed into seven distinct classes. The phylogenetic relationship differed between the two proteins, and we showed that homologous recombination plays a major role in creating alterations in the genetic switch, leading to new immunity classes. Analyses of the host integration site for these phages resulted in the discovery of a previously unknown site, and there were at least four regular integration sites. Interestingly, we found no case where phages of the same immunity class had different host attachment sites. The evolution of immunity and integration sites is complex, since it involves interactions both between the phages themselves and between phages and hosts, and often, both regulatory proteins and target DNA must change.
Rapid Succession within the
Veillonella
Population of a Developing Human Oral Biofilm In Situ
Authors: Palmer Robert J. , Diaz Patricia I. , Kolenbrander Paul E. 
Published: May 2006

ABSTRACT

Streptococci are the primary component of the multispecies oral biofilm known as supragingival dental plaque; they grow by fermentation of sugars to organic acids, e.g., lactic acid. Veillonellae, a ubiquitous component of early plaque, are unable to use sugars; they ferment organic acids, such as lactate, to a mixture of shorter-chain-length acids, CO
2
, and hydrogen. Certain veillonellae bind to (coaggregate with) streptococci in vitro. We show that, between 4 and 8 hours into plaque development, the dominant strains of
Veillonella
change in their phenotypic characteristics (coaggregation and antibody reactivity) as well as in their genotypic characteristics (16S RNA gene sequences as well as strain level fingerprint patterns). This succession is coordinated with the development of mixed-species bacterial colonies. Changes in community structure can occur very rapidly in natural biofilm development, and we suggest that this process may influence evolution within this ecosystem.
The
Haemophilus influenzae
Type b
hcsA
and
hcsB
Gene Products Facilitate Transport of Capsular Polysaccharide across the Outer Membrane and Are Essential for Virulence
Authors: Sukupolvi-Petty Soila , Grass Susan , StGeme Joseph W. 
Published: May 2006

ABSTRACT

Haemophilus influenzae
type b is a common cause of invasive bacterial disease, especially among children in underdeveloped countries. The type b polysaccharide capsule is a polymer of ribose and ribitol-5-phosphate and is a critical determinant of virulence. Expression of the type b capsule is dependent upon the
cap
b locus, which consists of three functionally distinct regions, designated regions 1 to 3. Region 3 contains the
hcsA
and
hcsB
genes, which share significant homology with genes that have been implicated in encapsulation in other pathogenic bacteria but have unclear functions. In this study, we inactivated
hcsA
alone,
hcsB
alone, and both
hcsA
and
hcsB
together and examined the effects of these mutations on polysaccharide transport and bacterial virulence properties. Inactivation of
hcsA
alone resulted in accumulation of polysaccharide in the periplasm and a partial decrease in surface-associated polysaccharide, whereas inactivation of
hcsB
alone or of both
hcsA
and
hcsB
together resulted in accumulation of polysaccharide in the periplasm and complete loss of surface-associated polysaccharide. All mutations eliminated serum resistance and abrogated bacteremia and mortality in neonatal rats. These results indicate that the
hcsA
and
hcsB
gene products have complementary functions involved in the transport of polysaccharide across the outer membrane and are essential for virulence.
Overexpression of PrfA Leads to Growth Inhibition ofListeria monocytogenesin Glucose-Containing Culture Media by Interfering with Glucose Uptake
Authors: Marr A. K. , Joseph B. , Mertins S. , Ecke R. , Müller-Altrock S. , Goebel W. 
Published: May 2006

ABSTRACTListeria monocytogenesstrains expressing high levels of the virulence regulator PrfA (mutant PrfA* or wild-type PrfA) show strong growth inhibition in minimal media when they are supplemented with glucose but not when they are supplemented with glucose-6-phosphate compared to the growth of isogenic strains expressing low levels of PrfA. A significantly reduced rate of glucose uptake was observed in a PrfA*-overexpressing strain growing in LB supplemented with glucose. Comparative transcriptome analyses were performed with RNA isolated from aprfAmutant and an isogenic strain carrying multiple copies ofprfAorprfA* on a plasmid. These analyses revealed that in addition to high transcriptional up-regulation of the known PrfA-regulated virulence genes (group I), there was less pronounced up-regulation of the expression of several phage and metabolic genes (group II) and there was strong down-regulation of several genes involved mainly in carbon and nitrogen metabolism in the PrfA*-overexpressing strain (group III). Among the latter genes are thenrgAB,gltAB, andglnRAoperons (involved in nitrogen metabolism), theilvBoperon (involved in biosynthesis of the branched-chain amino acids), and genes for some ABC transporters. Most of the down-regulated genes have been shown previously to belong to a class of genes inBacillus subtiliswhose expression is negatively affected by impaired glucose uptake. Our results lead to the conclusion that excess PrfA (or PrfA*) interferes with a component(s) essential for phosphotransferase system-mediated glucose transport.
Réactivité carbanionique de l'enchainement Pv—CH2—CH2—S—. Application à la synthèse d'un nouveau type de coordinats phosphorylés tétradentés
Authors: Savignac Monique , Cadiot Paul , Mathey François 
Published: May 2006

The tert-butyllithium metallation of compounds containing the group Pv—CH2—CH2—SR proceeds by elimination of the group SR (R = H, CH3) followed by addition of tert-BuLi. Application of this addition–elimination reaction to functionalized phosphine-oxides [Formula: see text] leads to the synthesis of γ-diphosphorylated compounds. These dissociate in basic medium following a mechanism which is the reverse of their formation as shown by treatment of the reaction mixture with p-chlorobenzaldehyde to give ethyl p-chlorocinnamate. [Journal Translation]
Calcul des déplacements chimiques par la méthode des perturbations finies au niveau INDO avec GIAO et approximation de London. I. 13C et 1H
Authors: Vauthier E. , Odiot S. , Tonnard F. 
Published: May 2006

A formalism for the calculation of σ in the finite perturbation method is developed by keeping hermitian the first order perturbed matrix in B. The σ formalism is separated into mono, di, and triatomic terms, and the importance of the electron densities of neighboring and remote bonds is shown. 13C chemical shifts depend only slightly on the remote bonds in contrast to those for 1H. A calculation of the screening constant for a series of 16 sp and sp2 carbons gives an average precision of 5 ppm for the 13C nuclei. [Journal Translation]
Spectres photoélectroniques de cyclohexène-2 ones-1 diversement substituées en position 3. Correlations avec la réactivité
Authors: Pfister-Guillouzo Geneviève , Geribaldi Serge , Gal Jean-François 
Published: May 2006

We have recorded the photoelectronic spectra of 32 differently 3-substituted 2-cyclohexen-1-ones as well as those of 10 para-substituted acetophenones. Assignment of most of the cyclohexenone bands is made and the substituent effects on the π-electron ionization potentials and of the oxygen lone pair are discussed. The linear relationship between the ionization potential of the carbonyl oxygen lone pair and σp-type constants as well as those between the ionization potentials and the enthalpies of complexation (ΔH0) of the ketones with BF3 in methylene chloride allows us to propose that the direct conjugative interaction between the substituents and the carbonyl group is weak in the free ketone but becomes very strong in the complexed or protonated state. The existence of two distinct relationships (ΔH0 = f(PI n0) for 3-substituted cyclohexenones and the aromatic ketones indicates that this type of expression cannot be used for the comparison of the Lewis basicities of different types of ketones; on the contrary, these expressions do allow for the comparison of the relative basicities of the same type. [Journal Translation]
Étude des bases de Schiff dérivées de la salicylaldehyde et de la 2-aminopyridine. Propriétés et capacité de complexation
Authors: Capitán-Vallvey L. F. , Salinas F. , Jiménez C. , Cuadros L. 
Published: May 2006

The spectroscopic (ir, uv, nmr, and ms) and thermal properties of N-(4-methyl-2-pyridyl)benzaldimine, N-(6-methyl-2-pyridyl)benzaldimine, N-(4-methyl-2-pyridyl)salicylaldimine and N-(6-methyl-2-pyridyl)salicylaldimine have been studied. Their acidity constants are discussed in relationship to their stereochemistry. Finally, reaction of these compounds with metal salts has been studied in a qualitative manner. [Journal Translation]
Synthèse de nucleosides pyrimidiques à partir de bromures de désoxy-4-pentopyranosyles non totalement protégés
Authors: Gagnieu Christian H. , Grouiller Annie V. , Pacheco Henri 
Published: May 2006

The synthesis of nucleosides 15–19 has been completed in high yield following the method of Hilbert–Johnson, by condensation of 2,4-dimethoxypyrimidine with bromo-4-deoxypento pyranosides in which the C-3 hydroxyl group is free. The presence of this group augments the reactivity of the bromides but does not appear to play an important role in the stereochemistry of the reaction, which is above all influenced by steric factors and the nature of the C-2 substituent. [Journal Translation]
Régiosélectivité de l'hydrogénation catalytique de quelques pyrido[2,3-b]pyrazines
Authors: Cosmao Jean-Marie , Collignon Noel , Queguiner Guy 
Published: May 2006

Catalytic hydrogenation on palladium–carbon in ethanol of several pyrido[2,3-b]pyrazines leads to mixtures of the 1,2,3,4- and 5,6,7,8-tetrahydro derivatives except in two cases: the reduction of the nonsubstituted heterocycle takes place on the pyrazine ring and, in the case of the 2,3-diphenyl derivative, the pyridine ring is reduced. In pure acetic acid this reduction provides only 1,2,3,4-tetrahydropyrido[2,3-b]pyrazines. A study of the reduction of 2,3-diphenylpyrido[2,3-b]pyrazine and several di- and tetrahydro derivatives as a function of solvent acidity suggests that the observed selectivity could result from the isomerization of partially hydrogenated intermediates. [Journal Translation]
Synthèse stéréospecifique de nucléosides pyrimidiques par la méthode de Hilbert–Johnson
Authors: Gagnieu Christian H. , Grouiller Annie V. , Pacheco Henri 
Published: May 2006

Condensation of 2,4-dimethoxy pyrimidine with bromoglucosides derived from methyl 4-deoxypentopyranosides 2–7 and from 3,5,6-tri-O-benzoyl glucofuranose, 20, leads in a stereospecific manner to the nucleosides 8–13 and 22 with the trans 1′,2′ configuration. The stereochemistry of this reaction is not influenced by the structure of the starting sugar but rather is directed by the presence of the C-2 hydroxyl group. The synthesis of epoxide 18, obtained by the action of NaH on the bromohydrine 17, derived from 7, supports the intervention of a reaction assisted by an epoxide-like intermediate derived from the trans-bromohydrine. On the other hand, the cis-bromohydrine undergoes direct substitution of anomeric halogen by base. The possibility of the formation of a carbocation-like intermediate is discounted since SN1 type glycosylation reactions of 19 by MeOH or t-BuOH lead preferentially to products with the cis-configuration. [Journal translation]
Acupuncture for Diagnostic Fiberoptic Bronchoscopy: A Prospective, Randomized, Placebo-Controlled Study
Authors: Cabrini Luca , Gioia Luigi , Gemma Marco , Melloni Giulio , Carretta Angelo , Ciriaco Paola , Puglisi Armando 
Published: May 2006

Patients usually fear fiberoptic bronchoscopy (FBS) and they report a low level of satisfaction after this examination. We evaluated the efficacy of acupuncture in decreasing patient anxiety before diagnostic FBS and in improving tolerance to the examination. In a prospective double-blind study, we enrolled 48 patients scheduled to undergo diagnostic FBS. Patients were randomly assigned to one of three groups. Group A (16 patients): standard FBS, with airway topic anesthesia; Group B (16 patients): standard FBS, with airway topic anesthesia and acupuncture treatment; Group C (16 patients): standard FBS, with airway topic anesthesia and sham acupuncture. EKG, non-invasive arterial pressure, and pulse oximetry were monitored on a routine basis. We evaluated patient anxiety before and after acupuncture and, at the end of FBS, the discomfort suffered during the examination by a 100-mm Visual Analog Scale (VAS).Patient satisfaction in Group A was 50% worse than in Group B ( p = 0.04). We observed a strong, even if not statistically significant, tendency toward a lower pre-FBS anxiety in Group B. Patients in group C had values very close to those recorded in group A. We observed no adverse event and no differences in cardio-respiratory parameters in these three groups; in particular, we did not observe a respiratory depression in Group B.Acupuncture seems an effective resource for a Thoracic Endoscopic Room to improve patient tolerance to FBS.
Role for Brm in Cell Growth Control
Authors: Coisy-Quivy Marjorie , Disson Olivier , Roure Virginie , Muchardt Christian , Blanchard Jean-Marie , Dantonel Jean-Christophe 
Published: May 2006

Abstract
Recently, we have shown implication of Brm, the catalytic subunit of the SWI/SNF chromatin remodeling complex, in repression of cyclin A expression in quiescent cells. Here, we have examined the fate of cells lacking Brm throughout the cycle. We find that despite elevated levels of cyclins A and E, these cells can respond to serum starvation, however, without reaching a canonical G0 phase as they continue to express high levels of c-Myc and have an abnormally large average size. The response to serum starvation can be correlated with increased levels of Rb proteins p130 and p107 as well as increased association of p27 with the cyclin-dependent kinases, possibly compensating for the higher levels of G1 cyclins by reducing their associated kinase activity. After serum stimulation, reentry into the cycle occurs normally, but the S phase is delayed and shorter. In addition, the M phase has an increased duration, and we observed frequent faulty chromosome segregation events in anaphase. Altogether, our data suggest that cells can partially overcome the absence of Brm by activating several compensatory mechanisms to control the cell cycle. However, they remain profoundly affected, unable to enter a canonical quiescent state, presenting a shorter S phase, and finally unable to perform correct chromosome segregation. (Cancer Res 2006; 66(10): 5069-76)
The Phosphoinositide 3-Kinase/Akt Pathway: A New Target in Human Renal Cell Carcinoma Therapy
Authors: Sourbier Carole , Lindner Véronique , Lang Hervé , Agouni Abdelali , Schordan Eric , Danilin Sabrina , Rothhut Sylvie , Jacqmin Didier , Helwig Jean-Jacques , Massfelder Thierry 
Published: May 2006

Abstract
Metastatic renal cell carcinoma is resistant to current therapies. The phosphoinositide 3-kinase (PI3K)/Akt signaling cascade induces cell growth, cell transformation, and neovascularization. We evaluated whether targeting this pathway could be of therapeutic value against human renal cell carcinoma. The activation of the PI3K/Akt pathway and its role in renal cell carcinoma progression was evaluated in vitro in seven human cell lines by Western blot, cell counting, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, terminal deoxyribonucleotide transferase–mediated nick-end labeling assays, and fluorescence-activated cell sorting analysis, using two PI3K inhibitors, LY294002 and wortmannin, as well as by transfection with various Akt constructs and through Akt knockdown by small interfering RNA (siRNA). In vivo nude mice bearing human renal cell carcinoma tumor xenografts were treated with LY294002 (75 mg/kg/wk, 4 weeks, i.p.). Tumor growth was measured and tumors were subjected to Western blot and immunohistochemical analysis. Akt was constitutively activated in all cell lines. Constitutive phosphorylation of glycogen synthase kinase-3 (GSK-3) was observed in all cell lines, whereas forkhead transcription factor and mammalian target of rapamycin, although expressed, were not constitutively phosphorylated. Exposure to LY294002 or wortmannin decreased Akt activation and GSK-3 phosphorylation and reduced cell growth by up to 70% through induction of cell apoptosis. These effects were confirmed by transfection experiments with Akt constructs or Akt siRNA. Importantly, LY294002 induced up to 50% tumor regression in mice through tumor cell apoptosis. Tumor neovascularization was significantly increased by LY294002 treatment. Blood chemistries showed no adverse effects of the treatment. Our results suggest an important role of PI3K/Akt inhibitors as a potentially useful treatment for patients with renal cell carcinoma. (Cancer Res 2006; 66(10): 5130-42)
Acetyl-CoA Carboxylase α Is Essential to Breast Cancer Cell Survival
Authors: Chajès Véronique , Cambot Marie , Moreau Karen , Lenoir Gilbert M. , Joulin Virginie 
Published: May 2006

Abstract
Activation of de novo fatty acid synthesis is a characteristic feature of cancer cells. We have recently described an interaction between acetyl-CoA carboxylase α (ACCα), a key enzyme in fatty acid synthesis, and BRCA1, which indicates a possible connection between lipid synthesis and genetic factors involved in susceptibility to breast and ovarian cancers. For this reason, we explored the role of ACCα in breast cancer cell survival using an RNA interference (RNAi) approach. We show that specific silencing of either the ACCα or the fatty acid synthase (FAS) genes in cancer cells results in a major decrease in palmitic acid synthesis. Depletion of the cellular pool of palmitic acid is associated with induction of apoptosis concomitant with the formation of reactive oxygen species (ROS) and mitochondrial impairment. Expression of a small interfering RNA (siRNA)–resistant form of ACCα mRNA prevented the effect of ACCα-RNAi but failed to prevent the effect of FAS gene silencing. Furthermore, supplementation of the culture medium with palmitate or with the antioxidant vitamin E resulted in the complete rescue of cells from both ACCα and FAS siRNA–induced apoptosis. Finally, human mammary epithelial cells are resistant to RNAi against either ACCα or FAS. These data confirm the importance of lipogenesis in cancer cell survival and indicate that this pathway represents a key target for antineoplastic therapy that, however, might require specific dietary recommendation for full efficacy. (Cancer Res 2006; 66(10): 5287-94)