bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution of the Mismatch DNA Repair System to the Generation of Stationary-Phase-Induced Mutants of
Bacillus subtilis
Authors: Pedraza-Reyes Mario , Yasbin Ronald E.
Published: September 2004

A reversion assay system previously implemented to demonstrate the existence of adaptive or stationary-phase-induced mutagenesis in
Bacillus subtilis
was utilized in this report to study the influence of the mismatch DNA repair (MMR) system on this type of mutagenesis. Results revealed that a strain deficient in MutSL showed a significant propensity to generate increased numbers of stationary-phase-induced revertants. These results suggest that absence or depression of MMR is an important factor in the mutagenesis of nongrowing
B. subtilis
cells because of the role of MMR in repairing DNA damage. In agreement with this suggestion, a significant decrease in the number of adaptive revertant colonies, for the three markers tested, occurred in
B. subtilis
cells which overexpressed a component of the MMR system. Interestingly, the single overexpression of
mutS
, but not of
mutL
, was sufficient to decrease the level of adaptive mutants in the reversion assay system of
B. subtilis
. The results presented in this work, as well as in our previous studies, appear to suggest that an MMR deficiency, putatively attributable to inactivation or saturation with DNA damage of MutS, may occur in a subset of
B. subtilis
cells that differentiate into the hypermutable state.
Two Proteins with Ornithine Acetyltransferase Activity Show Different Functions in
Streptomyces clavuligerus:
Oat2 Modulates Clavulanic Acid Biosynthesis in Response to Arginine
Authors: de la Fuente A. , Martín J. F. , Rodríguez-García A. , Liras P.
Published: September 2004

The
oat2
gene, located in the clavulanic acid gene cluster in
Streptomyces clavuligerus
, is similar to
argJ
, which encodes
N
-acetylornithine:glutamic acid acetyltransferase activity. Purified proteins obtained by expression in
Escherichia coli
of the
argJ
and
oat2
genes of
S. clavuligerus
posses
N
-acetyltransferase activity. The kinetics and substrate specificities of both proteins are very similar. Deletion of the
oat2
gene did not affect the total
N
-acetylornithine transferase activity and slightly reduced the formation of clavulanic acid under standard culture conditions. However, the
oat2
mutant produced more clavulanic acid than the parental strain in cultures supplemented with high levels (above 1 mM) of arginine. The purified
S. clavuligerus
ArgR protein bound the arginine box in the
oat2
promoter, and the expression of
oat2
was higher in mutants with a disruption in
argR
(arginine-deregulated), confirming that the Arg boxes of
oat2
are functional in vivo. Our results suggest that the Oat2 protein or one of its reaction products has a regulatory role that modulates clavulanic acid biosynthesis in response to high arginine concentrations.
N-Linked Protein Glycosylation Is Required for Full Competence in
Campylobacter jejuni
81-176
Authors: Larsen Joseph C. , Szymanski Christine , Guerry Patricia
Published: September 2004

The recent sequencing of the virulence plasmid of
Campylobacter jejuni
81-176 revealed the presence of genes homologous to type IV secretion systems (TFSS) that have subsequently been found in
Helicobacter pylori
and
Wolinella succinogenes
. Mutational analyses of some of these genes have implicated their involvement in intestinal epithelial cell invasion and natural competence. In this report, we demonstrate that one of these type IV secretion homologs, Cjp3/VirB10, is a glycoprotein. Treatment with various glycosidases and binding to soybean agglutinin indicated that the structure of the glycan present on VirB10 contains a terminal GalNAc, consistent with previous reports of N-linked glycans in
C. jejuni
. Site-directed mutagenesis of five putative N-linked glycosylation sites indicated that VirB10 is glycosylated at two sites, N32 and N97. Mutants in the N-linked general protein glycosylation (
pgl
) system of
C. jejuni
are significantly reduced in natural transformation, which is likely due, in part, to lack of glycosylation of VirB10. The natural transformation defect in a
virB10
mutant can be complemented in
trans
by using a plasmid expressing wild-type VirB10 or an N32A substitution but not by using a mutant expressing VirB10 with an N97A substitution. Taken together, these results suggest that glycosylation of VirB10 specifically at N97 is required for the function of the TFSS and for full competence in
C. jejuni
81-176.
Bifidobacterium longum
Requires a Fructokinase (Frk; ATP:
d
-Fructose 6-Phosphotransferase, EC 2.7.1.4) for Fructose Catabolism
Authors: Caescu Cristina I. , Vidal Olivier , Krzewinski Frédéric , Artenie Vlad , Bouquelet Stéphane
Published: September 2004

Although the ability of
Bifidobacterium
spp. to grow on fructose as a unique carbon source has been demonstrated, the enzyme(s) needed to incorporate fructose into a catabolic pathway has hitherto not been defined. This work demonstrates that intracellular fructose is metabolized via the fructose-6-P phosphoketolase pathway and suggests that a fructokinase (Frk; EC 2.7.1.4) is the enzyme that is necessary and sufficient for the assimilation of fructose into this catabolic route in
Bifidobacterium longum
. The
B. longum
A10C fructokinase-encoding gene (
frk
) was expressed in
Escherichia coli
from a pET28 vector with an attached N-terminal histidine tag. The expressed enzyme was purified by affinity chromatography on a Co
2+
-based column, and the pH and temperature optima were determined. A biochemical analysis revealed that Frk displays the same affinity for fructose and ATP (

K
m

fructose
= 0.739 ± 0.18 mM and

K
m

ATP
= 0.756 ± 0.08 mM), is highly specific for
d
-fructose, and is inhibited by an excess of ATP (>12 mM). It was also found that
frk
is inducible by fructose and is subject to glucose-mediated repression. Consequently, this work presents the first characterization at the molecular and biochemical level of a fructokinase from a gram-positive bacterium that is highly specific for
d
-fructose.
Activation of the Rcs Signal Transduction System Is Responsible for the Thermosensitive Growth Defect of anEscherichia coliMutant Lacking Phosphatidylglycerol and Cardiolipin
Authors: Shiba Yasuhiro , Yokoyama Yasuko , Aono Yoshiko , Kiuchi Takashi , Kusaka Jin , Matsumoto Kouji , Hara Hiroshi
Published: September 2004

The lethal effect of anEscherichia coli pgsAnull mutation, which causes a complete lack of the major acidic phospholipids, phosphatidylglycerol and cardiolipin, is alleviated by a lack of the major outer membrane lipoprotein encoded by thelppgene, but anlpp pgsAstrain shows a thermosensitive growth defect. Using transposon mutagenesis, we found that this thermosensitivity was suppressed by disruption of thercsC,rcsF, andyojNgenes, which code for a sensor kinase, accessory positive factor, and phosphotransmitter, respectively, of the Rcs phosphorelay signal transduction system initially identified as regulating the capsular polysaccharide synthesis (cps) genes. Disruption of thercsBgene coding for the response regulator of the system also suppressed the thermosensitivity, whereas disruption ofcpsEdid not. By monitoring the expression of acpsB′-lacfusion, we showed that the Rcs system is activated in thepgsAmutant and is reverted to a wild-type level by thercsmutations. These results indicate that envelope stress due to an acidic phospholipid deficiency activates the Rcs phosphorelay system and thereby causes the thermosensitive growth defect independent of the activation of capsule synthesis.
Towards Designer Cellulosomes in Clostridia: Mannanase Enrichment of the Cellulosomes Produced by
Clostridium cellulolyticum
Authors: Perret Stéphanie , Bélaich Anne , Fierobe Henri-Pierre , Bélaich Jean-Pierre , Tardif Chantal
Published: September 2004

The
man5K
gene of
Clostridium cellulolyticum
was cloned and overexpressed in
Escherichia coli
. This gene encodes a 424-amino-acid preprotein composed of an N-terminal leader peptide, followed by a dockerin module and a C-terminal catalytic module belonging to family 5 of the glycosyl hydrolases. Mature Man5K displays 62% identity with ManA from
Clostridium cellulovorans
. Two forms of the protein were purified from
E. coli
; one form corresponds to the full-length enzyme (45 kDa), and a truncated form (39 kDa) lacks the N-terminal dockerin module. Both forms exhibit the same typical family 5 mannanase substrate preference; they are very active with the galactomannan locust bean gum, and the more galacto-substituted guar gum molecules are degraded less. The truncated form, however, displays fourfold-higher activity with galactomannans than the full-length enzyme. Man5K was successfully overproduced in
C. cellulolyticum
by using expression vectors. The
trans
-produced protein was found to be incorporated into the cellulosomes and became one of the major enzymatic components. Modified cellulosomes displayed 20-fold-higher specific activities than control fractions on galactomannan substrates, whereas the specific activity on crystalline cellulose was reduced by 20%. This work clearly showed that the composition of the cellulosomes is obviously regulated by the relative amounts of the enzymes produced and that this composition can be engineered in clostridia by structural gene cloning.
Two Chimeric Chromosomes ofStreptomyces coelicolorA3(2) Generated by Single Crossover of the Wild-Type Chromosome and Linear Plasmid SCP1
Authors: Yamasaki Masayuki , Kinashi Haruyasu
Published: September 2004

Streptomyces coelicolorA3(2) strain 2106 carries a 1.85-Mb linear plasmid, SCP1′-cysD, in addition to a 7.2-Mb linear chromosome. Macrorestriction analysis indicated that both linear DNAs are hybrids of the wild-type chromosome and the linear plasmid SCP1 on each side. Nucleotide sequencing of the fusion junctions revealed no homology between the recombination regions. SCP1′-cysDcontains an SCP1 telomere and a chromosomal telomere at each end and therefore does not have terminal inverted repeats. In addition, SCP1′-cysDcould not be eliminated from strain 2106 by various mutagenic treatments. Thus, we concluded that both the 7.2-Mb chromosome and SCP1′-cysDare chimeric chromosomes generated by a single crossover of the wild-type chromosome and SCP1. This may be regarded as a model of chromosomal duplication in genome evolution.
Complete Genomic Sequence of Bacteriophage B3, a Mu-Like Phage of
Pseudomonas aeruginosa
Authors: Braid Michael D. , Silhavy Jennifer L. , Kitts Christopher L. , Cano Raul J. , Howe Martha M.
Published: September 2004

Bacteriophage B3 is a transposable phage of
Pseudomonas aeruginosa
. In this report, we present the complete DNA sequence and annotation of the B3 genome. DNA sequence analysis revealed that the B3 genome is 38,439 bp long with a G+C content of 63.3%. The genome contains 59 proposed open reading frames (ORFs) organized into at least three operons. Of these ORFs, the predicted proteins from 41 ORFs (68%) display significant similarity to other phage or bacterial proteins. Many of the predicted B3 proteins are homologous to those encoded by the early genes and head genes of Mu and Mu-like prophages found in sequenced bacterial genomes. Only two of the predicted B3 tail proteins are homologous to other well-characterized phage tail proteins; however, several Mu-like prophages and transposable phage D3112 encode approximately 10 highly similar proteins in their predicted tail gene regions. Comparison of the B3 genomic organization with that of Mu revealed evidence of multiple genetic rearrangements, the most notable being the inversion of the proposed B3 immunity/early gene region, the loss of Mu-like tail genes, and an extreme leftward shift of the B3 DNA modification gene cluster. These differences illustrate and support the widely held view that tailed phages are genetic mosaics arising by the exchange of functional modules within a diverse genetic pool.
Genome-Wide Molecular Clock and Horizontal Gene Transfer in Bacterial Evolution
Authors: Novichkov Pavel S. , Omelchenko Marina V. , Gelfand Mikhail S. , Mironov Andrei A. , Wolf Yuri I. , Koonin Eugene V.
Published: September 2004

We describe a simple theoretical framework for identifying orthologous sets of genes that deviate from a clock-like model of evolution. The approach used is based on comparing the evolutionary distances within a set of orthologs to a standard intergenomic distance, which was defined as the median of the distribution of the distances between all one-to-one orthologs. Under the clock-like model, the points on a plot of intergenic distances versus intergenomic distances are expected to fit a straight line. A statistical technique to identify significant deviations from the clock-like behavior is described. For several hundred analyzed orthologous sets representing three well-defined bacterial lineages, the α-Proteobacteria, the γ-Proteobacteria, and theBacillus-Clostridiumgroup, the clock-like null hypothesis could not be rejected for ∼70% of the sets, whereas the rest showed substantial anomalies. Subsequent detailed phylogenetic analysis of the genes with the strongest deviations indicated that over one-half of these genes probably underwent a distinct form of horizontal gene transfer, xenologous gene displacement, in which a gene is displaced by an ortholog from a different lineage. The remaining deviations from the clock-like model could be explained by lineage-specific acceleration of evolution. The results indicate that although xenologous gene displacement is a major force in bacterial evolution, a significant majority of orthologous gene sets in three major bacterial lineages evolved in accordance with the clock-like model. The approach described here allows rapid detection of deviations from this mode of evolution on the genome scale.
Symbiotic Autoregulation of
nifA
Expression in
Rhizobium leguminosarum
bv. viciae
Authors: Martínez Marta , Palacios José M. , Imperial Juan , Ruiz-Argüeso Tomás
Published: September 2004

NifA is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. In
Rhizobium leguminosarum
bv. viciae UPM791, the
nifA
gene is part of a gene cluster (
orf71 orf79 fixW orf5 fixABCX nifAB
) separated by 896 bp from an upstream and divergent truncated duplication of
nifH
(Δ
nifH
). Symbiotic expression analysis of genomic
nifA
::
lacZ
fusions revealed that in strain UPM791
nifA
is expressed mainly from a σ
54
-dependent promoter (P

nifA1

) located upstream of
orf71
. This promoter contains canonical NifA upstream activating sequences located 91 bp from the transcription initiation site. The transcript initiated in P

nifA1

spans 5.1 kb and includes
nifA
and
nifB
genes. NifA from
Klebsiella pneumoniae
was able to activate transcription from P

nifA1

in a heterologous
Escherichia coli
system. In
R. leguminosarum
, the P

nifA1

promoter is essential for effective nitrogen fixation in symbiosis with peas. In its absence, partially efficient nitrogen-fixing nodules were produced, and the corresponding bacteroids exhibited only low levels of
nifA
gene expression. The basal level of
nifA
expression resulted from a promoter activity originating upstream of the
fixX-nifA
intergenic region and probably from an incomplete duplication of P

nifA1

located immediately upstream of
fixA
.
Transcription Regulation by the
Mycobacterium tuberculosis
Alternative Sigma Factor SigD and Its Role in Virulence
Authors: Raman Sahadevan , Hazra Rohan , Dascher Christopher C. , Husson Robert N.
Published: September 2004

Mycobacterium tuberculosis
, an obligate mammalian pathogen, adapts to its host during the course of infection via the regulation of gene expression. Of the regulators of transcription that play a role in this response, several alternative sigma factors of
M. tuberculosis
have been shown to control gene expression in response to stresses, and some of these are required for virulence or persistence in vivo. For this study, we examined the role of the alternative sigma factor SigD in
M. tuberculosis
gene expression and virulence. Using microarray analysis, we identified several genes whose expression was altered in a strain with a
sigD
deletion. A small number of these genes, including
sigD
itself, the gene encoding the autocrine growth factor RpfC, and a gene of unknown function, Rv1815, appear to be directly regulated by this sigma factor. By identifying the in vivo promoters of these genes, we have determined a consensus promoter sequence that is putatively recognized by SigD. The expression of several genes encoding PE-PGRS proteins, part of a large family of related genes of unknown function, was significantly increased in the
sigD
mutant. We found that the expression of
sigD
is stable throughout log phase and stationary phase but that it declines rapidly with oxygen depletion. In a mouse infection model, the
sigD
mutant strain was attenuated, with differences in survival and the inflammatory response in the lung between mice infected with the mutant and those infected with the wild type.
Involvement of
exo5
in Production of Surface Polysaccharides in
Rhizobium leguminosarum
and Its Role in Nodulation of
Vicia sativa
subsp.
nigra
Authors: Laus Marc C. , Logman Trudy J. , van Brussel Anton A. N. , Carlson Russell W. , Azadi Parastoo , Gao Mu-Yun , Kijne Jan W.
Published: September 2004

Analysis of two exopolysaccharide-deficient mutants of
Rhizobium leguminosarum
, RBL5808 and RBL5812, revealed independent Tn
5
transposon integrations in a single gene, designated
exo5
. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in
exo5
affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo5-deficient rhizobia do not produce extracellular polysaccharide (EPS) or capsular polysaccharide (CPS), both of which contain glucuronic acid. Carbohydrate composition analysis and nuclear magnetic resonance studies demonstrated that EPS and CPS from the parent strain have very similar structures. Lipopolysaccharide (LPS) molecules produced by the mutant strains are deficient in galacturonic acid, which is normally present in the core and lipid A portions of the LPS. The sensitivity of
exo5
mutant rhizobia to hydrophobic compounds shows the involvement of the galacturonic acid residues in the outer membrane structure. Nodulation studies with
Vicia sativa
subsp.
nigra
showed that
exo5
mutant rhizobia are impaired in successful infection thread colonization. This is caused by strong agglutination of EPS-deficient bacteria in the root hair curl. Root infection could be restored by simultaneous inoculation with a Nod factor-defective strain which retained the ability to produce EPS and CPS. However, in this case colonization of the nodule tissue was impaired.
Coexistence ofWolbachiawithBuchnera aphidicolaand a Secondary Symbiont in the AphidCinara cedri
Authors: Gómez-Valero Laura , Soriano-Navarro Mario , Pérez-Brocal Vicente , Heddi Abdelaziz , Moya Andrés , García-Verdugo José Manuel , Latorre Amparo
Published: September 2004

Intracellular symbiosis is very common in the insect world. For the aphidCinara cedri, we have identified by electron microscopy three symbiotic bacteria that can be characterized by their different sizes, morphologies, and electrodensities. PCR amplification and sequencing of the 16S ribosomal DNA (rDNA) genes showed that, in addition to harboringBuchnera aphidicola, the primary endosymbiont of aphids,C. cedriharbors a secondary symbiont (S symbiont) that was previously found to be associated with aphids (PASS, or R type) and an α-proteobacterium that belongs to theWolbachiagenus. Using in situ hybridization with specific bacterial probes designed for symbiont 16S rDNA sequences, we have shown thatWolbachiawas represented by only a few minute bacteria surrounding the S symbionts. Moreover, the observedB. aphidicolaand the S symbionts had similar sizes and were housed in separate specific bacterial cells, the bacteriocytes. Interestingly, in contrast to the case for all aphids examined thus far, the S symbionts were shown to occupy a similarly sized or even larger bacteriocyte space thanB. aphidicola. These findings, along with the facts thatC. cedriharbors theB. aphidicolastrain with the smallest bacterial genome and that the S symbionts infect allCinaraspp. analyzed so far, suggest the possibility of bacterial replacement in these species.
Substrate Binding Analysis of the 23S rRNA Methyltransferase RrmJ
Authors: Hager Jutta , Staker Bart L. , Jakob Ursula
Published: September 2004

The 23S rRNA methyltransferase RrmJ (FtsJ) is responsible for the 2′-O methylation of the universally conserved U2552 in the A loop of 23S rRNA. This 23S rRNA modification appears to be critical for ribosome stability, because the absence of functional RrmJ causes the cellular accumulation of the individual ribosomal subunits at the expense of the functional 70S ribosomes. To gain insight into the mechanism of substrate recognition for RrmJ, we performed extensive site-directed mutagenesis of the residues conserved in RrmJ and characterized the mutant proteins both in vivo and in vitro. We identified a positively charged, highly conserved ridge in RrmJ that appears to play a significant role in 23S rRNA binding and methylation. We provide a structural model of how the A loop of the 23S rRNA binds to RrmJ. Based on these modeling studies and the structure of the 50S ribosome, we propose a two-step model where the A loop undocks from the tightly packed 50S ribosomal subunit, allowing RrmJ to gain access to the substrate nucleotide U2552, and where U2552 undergoes base flipping, allowing the enzyme to methylate the 2′-O position of the ribose.
Importance of
Rhodospirillum rubrum
H
+
-Pyrophosphatase under Low-Energy Conditions
Authors: García-Contreras Rodolfo , Celis Heliodoro , Romero Irma
Published: September 2004

The physiological role of the membrane-bound pyrophosphatase of
Rhodospirillum rubrum
was investigated by the characterization of a mutant strain. Comparisons of growth levels between the wild type and the mutant under different low-potential conditions and during transitions between different metabolisms indicate that this enzyme provides
R. rubrum
with an alternative energy source that is important for growth in low-energy states.
Major Role of NAD-Dependent Lactate Dehydrogenases in Aerobic Lactate Utilization in
Lactobacillus plantarum
during Early Stationary Phase
Authors: Goffin Philippe , Lorquet Frédérique , Kleerebezem Michiel , Hols Pascal
Published: September 2004

NAD-independent lactate dehydrogenases are commonly thought to be responsible for lactate utilization during the stationary phase of aerobic growth in
Lactobacillus plantarum
. To substantiate this view, we constructed single and double knockout mutants for the corresponding genes,
loxD
and
loxL
. Lactate-to-acetate conversion was not impaired in these strains, while it was completely blocked in mutants deficient in NAD-dependent lactate dehydrogenase activities, encoded by the
ldhD
and
ldhL
genes. We conclude that NAD-dependent but not NAD-independent lactate dehydrogenases are involved in this process.
Recent Genetic Transfer between
Lactococcus lactis
and Enterobacteria
Authors: Bolotin Alexander , Quinquis Benoit , Sorokin Alexei , Ehrlich Dusko S.
Published: September 2004

The genome sequence of
Lactococcus lactis
revealed that the
ycdB
gene was recently exchanged between lactococci and enterobacteria. The present study of
ycdB
orthologs suggests that
L. lactis
was probably the gene donor and reveals three instances of gene transfer to enterobacteria. Analysis of
ycdB
gene transfer between two
L. lactis
subspecies,
L. lactis
subsp.
lactis
and
L. lactis
subsp.
cremoris
, indicates that the gene can be mobilized, possibly by conjugation.
LIMITS ON THE DIPOLE MOMENTS OF THE τ-LEPTON VIA THE PROCESS e+e-→τ+τ-γ IN A LEFT–RIGHT SYMMETRIC MODEL
Authors: GUTIÉRREZ-RODRÍGUEZ A. , LUIS-NORIEGA L. N. , HERNÁNDEZ-RUÍZ M. A.
Published: September 2004

Limits on the anomalous magnetic moment and the electric dipole moment of the τ lepton are calculated through the reaction e+e-→τ+τ-γ at the Z1-pole and in the framework of a left–right symmetric model. The results are based on the recent data reported by the L3 collaboration at CERN LEP. Due to the stringent limit of the model mixing angle ϕ, the effect of this angle on the dipole moments is quite small.
THE RADIATIVE h0(A0)→γγ DECAYS IN THE TWO-HIGGS DOUBLET MODEL
Authors: ILTAN E. O.
Published: September 2004

We study the radiative h0(A0)→γγ decays in the framework of the general two-Higgs doublet model, the so-called model III. We estimate the decay width of the processes at the order of magnitude of 10-2 GeV for the intermediate values of the Yukawa couplings. We observe that the analysis of the two-photon system provides a comprehensive information for the complex nature of the Yukawa couplings and therefore, the source of the CP violation.
SYMMETRY-PRESERVING LOOP REGULARIZATION AND RENORMALIZATION OF QFTs
Authors: WU YUE-LIANG
Published: September 2004

A new symmetry-preserving loop regularization method proposed in Ref. 1 is further investigated. It is found that its prescription can be understood by introducing a regulating distribution function to the proper-time formalism of irreducible loop integrals. The method simulates in many interesting features to the momentum cutoff, Pauli–Villars and dimensional regularization. The loop regularization method is also simple and general for the practical calculations to higher loop graphs and can be applied to both underlying and effective quantum field theories including gauge, chiral, supersymmetric and gravitational ones as the new method does not modify either the Lagrangian formalism or the spacetime dimension of original theory. The appearance of characteristic energy scale Mc and sliding energy scale μs offers a systematic way for studying the renormalization-group evolution of gauge theories in the spirit of Wilson–Kadanoff and for exploring important effects of higher dimensional interaction terms in the infrared regime.
PROTON DECAY IN SUPERSYMMETRIC GUT MODELS
Authors: WIESENFELDT SÖREN
Published: September 2004

The instability of protons is a crucial prediction of supersymmetric GUTs. We review the decay in minimal supersymmetric SU (5), which is dominated by dimension-five operators, and discuss the implications of the failure of Yukawa unification for the decay rate. In a consistent SU (5) model, where SU (5) relations among Yukawa couplings hold, the proton decay rate can be several orders of magnitude smaller than the present experimental bound. Finally, we discuss orbifold GUTs, where proton decay via dimension-five operators is absent. The branching ratios of dimension-six decay can significantly differ from those in four dimensions.
NONCOMMUTATIVE U(1) GAUGE THEORY AS A NONLINEAR SIGMA MODEL
Authors: YDRI BADIS
Published: September 2004

Noncommutative U (1) gauge theory in four dimensions is shown to be equivalent in some scaling limit to an ordinary nonlinear sigma model in two dimensions. The model in this regime is solvable and the corresponding exact beta function is found. We also show that classical U (n) gauge theory on [Formula: see text] can be approximated by a sequence of ordinary (d-2)-dimensional Georgi–Glashow models with gauge groups U (n(L+1)), where L+1 is the matrix size of the regularized noncommutative plane [Formula: see text].
THE TRIPLE BOTTOM LINE AND IMPACT ASSESSMENT: HOW DO TBL, EIA, SIA, SEA AND EMS RELATE TO EACH OTHER?
Authors: VANCLAY FRANK
Published: September 2004

Triple bottom line (TBL) reporting is a concept that is sweeping across the business sector, government and NGOs. However, many of the issues faced by consideration of the social in TBL are very similar to issues faced by social impact assessment (SIA) in its connections with biophysical environmental impact assessment (EIA) and the financial considerations associated with projects including economic and fiscal impact assessment, and cost-benefit analysis. It would appear that the advocates of TBL and the institutions that have adopted TBL are ignorant of SIA and other forms of impact assessment. The view presented here is that TBL is a fad that presents little that is new, and that TBL would learn a great deal by considering the experience of SIA.
METHANE GAS EMISSIONS FROM LANDFILL: OPPORTUNITIES AND CONSTRAINTS — THE CASE OF AL-RUSSIFA CITY
Authors: MRAYYAN BASSAM
Published: September 2004

The aim of this study was to illustrate the methane gas impacts on AL-Russifa region, Jordan, in addition to the opportunities and obstacles faced. AL-Russifa city suffers serious health and environmental problems as a result of the methane gas emissions from Al-Russifa Landfill.

The uncontrolled methane emissions and the potential of collection, use for producing electricity and the existing activities that include the biogas plant and regulations were analyzed and recommendations presented. The required institutional management and social structure that promote the proper management of solid waste that affect methane emissions need to be advanced through technological exchanges and training programs. Improving the existing biogas project and the establishment of new ones can reduce green house gases while generating electricity; thus reducing Jordan's dependency on imported oil.

The lack of financial, technical expertise and awareness among public and private sectors, in addition to the bureaucracy and the short time pay back phenomena are all considered as constraints for achieving such prosperous environmental projects. Establishing upgraded institutions will need to embrace improved capability to generate replicable projects that serve as a vehicle for solving pollution problems and promoting sustainable development.
Intracellular signaling specificity in response to uniaxial vs. multiaxial stretch: implications for mechanotransduction
Authors: Hornberger Troy A. , Armstrong Dustin D. , Koh Timothy J. , Burkholder Thomas J. , Esser Karyn A.
Published: September 2004

Several lines of evidence suggest that muscle cells can distinguish between specific mechanical stimuli. To test this concept, we subjected C2C12myotubes to cyclic uniaxial or multiaxial stretch. Both types of stretch induced an increase in extracellular signal-regulated kinase (ERK) and protein kinase B (PKB/Akt) phosphorylation, but only multiaxial stretch induced ribosomal S6 kinase (p70S6k) phosphorylation. Further results demonstrated that the signaling events specific to multiaxial stretch (p70S6kphosphorylation) were elicited by forces delivered through the elastic culture membrane and were not due to greater surface area deformations or localized regions of large tensile strain. Experiments performed using medium that was conditioned by multiaxial stretched myotubes indicated that a release of paracrine factors was not sufficient for the induction of signaling to p70S6k. Furthermore, incubation with gadolinium(III) chloride (500 μM), genistein (250 μM), PD-98059 (250 μM), bisindolylmaleimide I (20 μM), or LY-294002 (100 μM ) did not block the multiaxial stretch-induced signaling to p70S6k. However, disrupting the actin cytoskeleton with cytochalasin D did block the multiaxial signaling to p70S6k, with no effect on signaling to PKB/Akt. These results demonstrate that specific types of mechanical stretch activate distinct signaling pathways, and we propose that this occurs through direct mechanosensory-mechanotransduction mechanisms and not through previously defined growth factor/receptor binding pathways.
ATP regulates anion channel-mediated organic osmolyte release from cultured rat astrocytes via multiple Ca2+-sensitive mechanisms
Authors: Mongin Alexander A. , Kimelberg Harold K.
Published: September 2004

Ubiquitously expressed volume-regulated anion channels (VRACs) are activated in response to cell swelling but may also show limited activity in nonswollen cells. VRACs are permeable to inorganic anions and small organic osmolytes, including the amino acids aspartate, glutamate, and taurine. Several recent reports have demonstrated that neurotransmitters or hormones, such as ATP and vasopressin, induce or strongly potentiate astrocytic whole cell Cl− currents and amino acid release, which are inhibited by VRAC blockers. In the present study, we explored the intracellular signaling mechanisms mediating the effects of ATP on d-[3H]aspartate release via the putative VRAC pathway in rat primary astrocyte cultures. Cells were exposed to moderate (5%) or substantial (30%) reductions in medium osmolarity. ATP strongly potentiated d-[3H]aspartate release in both moderately swollen and substantially swollen cells. These ATP effects were blocked (≥80% inhibition) by intracellular Ca2+ chelation with BAPTA-AM, calmodulin inhibitors, or a combination of the inhibitors of protein kinase C (PKC) and calmodulin-dependent kinase II (CaMK II). In contrast, control d-[3H]aspartate release activated by the substantial hyposmotic swelling showed little (≤25% inhibition) sensitivity to the same pharmacological agents. These data indicate that ATP regulates VRAC activity via two separate Ca2+-sensitive signaling cascades involving PKC and CaMK II and that cell swelling per se activates VRACs via a separate Ca2+/calmodulin-independent signaling mechanism. Ca2+-dependent organic osmolyte release via VRACs may contribute to the physiological functions of these channels in the brain, including astrocyte-to-neuron intercellular communication.
Increased expression of poly(ADP-ribose) polymerase-1 contributes to caspase-independent myocyte cell death during heart failure
Authors: Pillai Jyothish B. , Russell Hyde M. , Raman Jai , Jeevanandam Valluvan , Gupta Mahesh P.
Published: September 2004

Poly(ADP-ribose) polymerase-1 (PARP-1) plays a pivotal role in regulating genome stability, cell cycle progression, and cell survival. However, overactivation of PARP has been shown to contribute to cell death and organ failure in various stress-related disease conditions. In this study, we examined the role of PARP in the development and progression of cardiac hypertrophy. We measured the expression of PARP in mouse hearts with physiological (swimming exercise) and pathological (aortic banding) cardiac hypertrophy as well as in human heart samples taken at the time of transplantation. PARP levels were elevated both in swimming and banded mice hearts and demonstrated a linear positive correlation with the degree of cardiac hypertrophy. A dramatic increase (4-fold) of PARP occurred in 6-wk banded mice, accompanied by apparent signs of ventricular dilation and myocyte cell death. PARP levels were also elevated (2- to 3-fold) in human hearts with end-stage heart failure compared with controls. However, we found no evidence of caspase-mediated PARP cleavage in either mouse or human failing hearts. Overexpression of PARP in primary cultures of cardiac myocytes led to suppression of gene expression and robust myocyte cell death. Furthermore, data obtained from the analysis of PARP knockout mice revealed that these hearts produce an attenuated hypertrophic response to aortic banding compared with controls. Together, these results demonstrate a role for PARP in the onset and progression of cardiac hypertrophy and suggest that some events related to cardiac hypertrophy growth and progression to heart failure are mediated by a PARP-dependent mechanism.
The role of the glia limitans in ADP-induced pial arteriolar relaxation in intact and ovariectomized female rats
Authors: Xu Hao-Liang , Ye Shuhua , Baughman Verna L. , Feinstein Douglas L. , Pelligrino Dale A.
Published: September 2004

We examined whether the glia limitans (GL) influences pial arteriolar relaxation elicited in vivo by the purinergic (P2Y1 receptor) agonist ADP in female rats, and whether that influence is altered in ovariectomized (Ovx) females. A validated model for GL injury was used, topical application of the gliotoxin l-α-aminoadipic acid (l-αAAA), 24 h before the study. In both intact and Ovx females, l-αAAA had no effect on responses to the NO donor, S-nitroso- N-acetyl penicillamine, but ADP-induced pial arteriolar dilations were significantly reduced (by 33–90%), compared with vehicle-treated controls. When NG-nitro-l-arginine (l-NNA) was administered to l-αAAA-treated rats, the ADP response was virtually lost in intact females, but no further reductions were observed in the Ovx rats. On the other hand, in l-αAAA-treated Ovx females, when the gap junction blocker, Gap 27, was subsequently added to the suffusate, ADP reactivity fell to very low levels. In vehicle-treated control rats, l-NNA and Gap 27 reduced ADP reactivity by ∼50% in intact and Ovx females, respectively. An earlier study indicated that the endothelium was a key site of influence for l-NNA (intact) and Gap 27 (Ovx). Thus present and previous results imply that the ADP response in pial arterioles represents the additive actions of an endothelial and a GL component. That supposition was confirmed in the present study by the finding that combining endothelial and GL injury produced an essentially complete loss of ADP reactivity in both intact and Ovx females. Finally, topical application of the selective P2Y1 antagonist, MRS-2179, was associated with a nearly complete suppression of the ADP response in both intact and Ovx females. These results suggest that 1) ADP-induced pial arteriolar dilation involves additive contributions from P2Y1 receptors present in both vascular endothelium and the GL; 2) the influence of the GL component is not altered by ovariectomy; and 3) the gap junction-dependent component of the ADP response in Ovx females is unlikely to include the GL and probably resides in the vessels themselves.
Thyroid status and endothelium-dependent vasodilation in skeletal muscle
Authors: McAllister R. M. , Albarracin I. , Jasperse J. L. , Price E. M.
Published: September 2004

Cardiovascular dysfunction is characteristic of both hypo- and hyperthyroidism. Endothelium-dependent dilation of conductance vessels is impaired in hypothyroidism but augmented in hyperthyroidism. We hypothesized that these alterations in dilation extend into the resistance vasculature of skeletal muscle. To test this hypothesis, rats were made hypothyroid with propylthiouracil (Hypo; n = 13) or hyperthyroid with triiodothyronine (Hyper; n = 9) over 3–4 mo. Compared with euthyroid controls (Eut; n = 14), Hypo rats were characterized by reduced skeletal muscle oxidative capacity and blunted growth; Hyper rats exhibited increased muscle oxidative capacity and left ventricular hypertrophy ( P < 0.05 for all effects). Vasodilation to the endothelium-dependent agent acetylcholine (∼2 × 10−4 M) in skeletal muscle was determined in situ. Conductance in certain muscles increased from control [e.g., soleus: 0.98 ± 0.15 (Eut), 0.79 ± 0.14 (Hypo), and 1.06 ± 0.24 ml·min−1·100 g−1·mmHg−1 (Hyper); not significant among groups] to acetylcholine [1.91 ± 0.21 (Eut), 2.28 ± 0.26 (Hypo), and 2.15 ± 0.33 ml·min−1·100 g−1·mmHg−1 (Hyper); P < 0.05 vs. control values for all groups] but did not differ among groups. Expression of mRNA for the endothelial isoform of nitric oxide synthase in resistance vessels isolated from various muscles was similarly unchanged with alterations in thyroid status [e.g., soleus 1A arterioles: 33.15 ± 0.58 (Eut), 32.73 ± 0.27 (Hypo), and 32.80 ± 0.54 (Hyper) cycles at threshold; not significant]. These data suggest that endothelium-dependent dilation of resistance vasculature in skeletal muscle is unchanged in both hypo- and hyperthyroidism. These data also emphasize the importance of examining resistance vasculature to improve understanding of effects of chronic disease on integrated cardiovascular function.
Activation of Metabotropic Glutamate Receptors Inhibits High-Voltage-Gated Calcium Channel Currents of Chicken Nucleus Magnocellularis Neurons
Authors: Lu Yong , Rubel Edwin W
Published: September 2004

Using whole cell patch-clamp recordings, we pharmacologically characterized the voltage-gated Ca2+ channel (VGCC) currents of chicken nucleus magnocellularis (NM) neurons using barium as the charge carrier. NM neurons possessed both low- and high-voltage-activated Ca2+ channel currents (HVA IBa2+). The N-type channel blocker (ω-conotoxin-GVIA) inhibited more than half of the total HVA IBa2+, whereas blockers of L- and P/Q-type channels each inhibited a small fraction of the current. Metabotropic glutamate receptor (mGluR)-mediated modulation of the HVA IBa2+ was examined by bath application of glutamate (100 μM), which inhibited the HVA IBa2+ by an average of 16%. The inhibitory effect was dose dependent and was partially blocked by ω-conotoxin-GVIA, indicating that mGluRs modulate N and other type HVA IBa2+. The nonspecific mGluR agonist, (1S,3R)-1-aminocyclopentane-1,3-dicarbosylic acid (1S,3R-ACPD), mimicked the inhibitory effect of glutamate on HVA IBa2+. Group I–III mGluR agonists showed inhibition of the HVA current with the most potent being the group III agonist l(+)-2-amino-4-phosphonobutyric acid. 1S,3R-ACPD (200 μM) had no effect on K+ or Na+ currents. The firing properties of NM neurons were also not altered by 1S,3R-ACPD. We propose that the inhibition of VGCC currents by mGluRs limits depolarization-induced Ca2+ entry into these highly active NM neurons and regulates their Ca2+ homeostasis.
Neural Representation of Vocalizations in the Primate Ventrolateral Prefrontal Cortex
Authors: Romanski Lizabeth M. , Averbeck Bruno B. , Diltz Mark
Published: September 2004

In this study, we examined the role of the ventrolateral prefrontal cortex in encoding communication stimuli. Specifically, we recorded single-unit responses from the ventrolateral prefrontal cortext (vlPFC) in awake behaving rhesus macaques in response to species-specific vocalizations. We determined the selectivity of vlPFC cells for 10 types of rhesus vocalizations and also asked what types of vocalizations cluster together in the neuronal response. The data from the present study demonstrate that vlPFC auditory neurons respond to a variety of species-specific vocalizations from a previously characterized library. Most vlPFC neurons responded to two to five vocalizations, while a small percentage of cells responded either selectively to a particular vocalization type or nonselectively to most auditory stimuli tested. Use of information theoretic approaches to examine vocalization tuning indicates that on average, vlPFC neurons encode information about one or two vocalizations. Further analysis of the types of vocalizations that vlPFC cells typically respond to using hierarchical cluster analysis suggests that the responses of vlPFC cells to multiple vocalizations is not based strictly on the call's function or meaning but may be due to other features including acoustic morphology. These data are consistent with a role for the primate vlPFC in assessing distinctive acoustic features.
Phosphene Induction and the Generation of Saccadic Eye Movements by Striate Cortex
Authors: Tehovnik E. J. , Slocum W. M. , Carvey C. E. , Schiller P. H.
Published: September 2004

The purpose of this review is to critically examine phosphene induction and saccadic eye movement generation by electrical microstimulation of striate cortex (area V1) in humans and monkeys. The following issues are addressed: 1) Properties of electrical stimulation as they pertain to the activation of V1 elements; 2) the induction of phosphenes in sighted and blind human subjects elicited by electrical stimulation using various stimulation parameters and electrode types; 3) the induction of phosphenes with electrical microstimulation of V1 in monkeys; 4) the generation of saccadic eye movements with electrical microstimulation of V1 in monkeys; and 5) the tasks involved for the development of a cortical visual prosthesis for the blind. In this review it is concluded that electrical microstimulation of area V1 in trained monkeys can be used to accelerate the development of an effective prosthetic device for the blind.
Generation of a bovine oocyte cDNA library and microarray: resources for identification of genes important for follicular development and early embryogenesis
Authors: Yao Jianbo , Ren Xiaoning , Ireland James J. , Coussens Paul M. , Smith Timothy P. L. , Smith George W.
Published: September 2004

The oocyte is a key regulator of ovarian folliculogenesis and early embryonic development. However, the composition of the oocyte transcriptome and identities and functions of key oocyte-specific genes involved in the above processes are relatively unknown. Using a PCR-based cDNA amplification method (SMART technology), we constructed a bovine oocyte cDNA library. Analysis of 230 expressed sequence tags (ESTs) from this library identified 102 unique sequences. Although some correspond to housekeeping genes (e.g., ribosomal protein L15) and some represent genes previously known to be expressed in oocytes and other tissues, most encode for genes whose expression in mammalian oocytes has not been reported previously (e.g., cocaine- and amphetamine-regulated transcript) or genes of unknown function. Sixteen did not show significant sequence similarity to any entries in the GenBank database and were classified as novel. Using over 2,000 unsequenced, randomly selected cDNA clones from the library, we constructed an oocyte microarray and performed experiments to identify genes preferentially expressed in fetal ovary (an enriched source of oocytes) relative to somatic tissues. Eleven clones were identified by microarray analysis with consistently higher expression in fetal ovaries (collected from animals at days 210–260 of gestation) compared with spleen and liver. DNA sequence analysis of these clones revealed that two correspond to JY-1, a novel bovine oocyte-specific gene. The remaining nine clones represent five identified genes and one additional completely novel gene. Increased abundance of mRNA in fetal ovary for five of the six genes identified was confirmed by real-time PCR. Results demonstrate the potential utility of these unique resources for identification of oocyte-expressed genes potentially important for reproductive function.
The radius of starlikeness for convex functions of complex order
Authors: Polatoglu Yaşar , Bolcal Metin , Şen Arzu
Published: September 2004

We will give the relation between the class of Janowski starlike
functions of complex order and the class of Janowski convex
functions of complex order. As a corollary of this relation, we
obtain the radius of starlikeness for the class of Janowski convex
functions of complex order.
On scalar type spectral operators, infinite differentiable and Gevrey ultradifferentiable C0‐semigroups
Authors: Markin Marat V.
Published: September 2004

Necessary and sufficient conditions for a scalar type spectral
operator in a Banach space to be a generator of an infinite
differentiable or a Gevrey ultradifferentiable C0‐semigroup
are found, the latter formulated exclusively in terms of the
operator′s spectrum.
Units in families of totally complex algebraic number fields
Authors: Vulakh L. Ya.
Published: September 2004

Multidimensional continued fraction algorithms associated with
GLn(ℤk), where ℤk is the ring of integers of an imaginary quadratic field K, are introduced and applied to find systems of fundamental units in families of totally
complex algebraic number fields of degrees four, six, and eight.
Stability of multipliers on Banach algebras
Authors: Miura Takeshi , Hirasawa Go , Takahasi Sin-Ei
Published: September 2004

Suppose A is a Banach algebra without order. We show that an
approximate multiplier T : A → A is an exact multiplier. We also consider an approximate multiplier T on a Banach algebra which need not be without order. If, in addition,
T is approximately additive, then we prove the
Hyers‐Ulam‐Rassias stability of T.