bluuebunny/crossref_metadata_2025_split huggingface dataset:
d-Ribulose-5-Phosphate 3-Epimerase: Cloning and Heterologous Expression of the Spinach Gene, and Purification and Characterization of the Recombinant Enzyme1
Authors: Chen Yuh-Ru , Hartman Fred C. , Lu Tse-Yuan S. , Larimer Frank W. 
Published: July 2002

Abstract
We have achieved, to our knowledge, the first high-level heterologous expression of the gene encodingd-ribulose-5-phosphate 3-epimerase from any source, thereby permitting isolation and characterization of the epimerase as found in photosynthetic organisms. The extremely labile recombinant spinach (Spinacia oleracea L.) enzyme was stabilized bydl-α-glycerophosphate or ethanol and destabilized byd-ribulose-5-phosphate or 2-mercaptoethanol. Despite this lability, the unprecedentedly high specific activity of the purified material indicates that the structural integrity of the enzyme is maintained throughout isolation. Ethylenediaminetetraacetate and divalent metal cations did not affect epimerase activity, thereby excluding a requirement for the latter in catalysis. As deduced from the sequence of the cloned spinach gene and the electrophoretic mobility under denaturing conditions of the purified recombinant enzyme, its 25-kD subunit size was about the same as that of the corresponding epimerases of yeast and mammals. However, in contrast to these other species, the recombinant spinach enzyme was octameric rather than dimeric, as assessed by gel filtration and polyacrylamide gel electrophoresis under nondenaturing conditions. Western-blot analyses with antibodies to the purified recombinant enzyme confirmed that the epimerase extracted from spinach leaves is also octameric.
Fusicoccin, 14-3-3 Proteins, and Defense Responses in Tomato Plants1
Authors: Roberts Michael R. , Bowles Dianna J. 
Published: July 2002

AbstractFusicoccin (FC) is a fungal toxin that activates the plant plasma membrane H+-ATPase by binding with 14-3-3 proteins, causing membrane hyperpolarization. Here we report on the effect of FC on a gene-for-gene pathogen-resistance response and show that FC application induces the expression of several genes involved in plant responses to pathogens. Ten members of the FC-binding 14-3-3 protein gene family were isolated from tomato (Lycopersicon esculentum) to characterize their role in defense responses. Sequence analysis is suggestive of common biochemical functions for these tomato 14-3-3 proteins, but their genes showed different expression patterns in leaves after challenges. Different specific subsets of 14-3-3 genes were induced after treatment with FC and during a gene-for-gene resistance response. Possible roles for the H+-ATPase and 14-3-3 proteins in responses to pathogens are discussed.
Stage- and Tissue-Specific Expression of Ethylene Receptor Homolog Genes during Fruit Development in Muskmelon1
Authors: Sato-Nara Kumi , Yuhashi Ken-Ichi , Higashi Katsumi , Hosoya Kazushige , Kubota Mitsuru , Ezura Hiroshi 
Published: July 2002

Abstract
We isolated two muskmelon (Cucumis melo) cDNA homologs of the Arabidopsis ethylene receptor genes ETR1 andERS1 and designated them Cm-ETR1(C.meloETR1; accession no. AF054806) andCm-ERS1 (C.meloERS1; accession no. AF037368), respectively. Northern analysis revealed that the level of Cm-ERS1mRNA in the pericarp increased in parallel with the increase in fruit size and then markedly decreased at the end of enlargement. In fully enlarged fruit the level of Cm-ERS1 mRNA was low in all tissues, whereas that of Cm-ETR1 mRNA was very high in the seeds and placenta. During ripening Cm-ERS1 mRNA increased slightly in the pericarp of fruit before the marked increase of Cm-ETR1 mRNA paralleled climacteric ethylene production. These results indicate that both Cm-ETR1 andCm-ERS1 play specific roles not only in ripening but also in the early development of melon fruit and that they have distinct roles in particular fruit tissues at particular developmental stages.
Aluminum Tolerance Genes on the Short Arm of Chromosome 3R Are Linked to Organic Acid Release in Triticale
Authors: Ma Jian Feng , Taketa Shin , Yang Zhen Ming 
Published: July 2002

Abstract
Triticale, a hybrid between wheat and rye, shows a high degree of Al tolerance that is inherited from rye, but the mechanisms of high Al tolerance in both rye and triticale are unknown. We found that the short arm of chromosome 3R carries genes necessary for Al tolerance in triticale (×Triticosecale Wittmark cv Currency). Detailed comparative studies with a 3DS.3RL translocation line (ST22) and a non-substitution line (ST2) were conducted. Root elongation was similarly inhibited by Al in ST2 and ST22 during the first 12 h of Al treatment, but more strongly in ST22 than in ST2 at 18 h and thereafter. The root inhibition induced by other metals (Cu, Cd, and La) was similar between ST2 and ST22, suggesting that the action of the genes for Al tolerance on the short arm of triticale chromosome 3R is highly specific to Al. A 2-fold larger amount of malate and citrate was released from the roots of ST2 than from ST22 at 12 and 18 h after Al treatment, respectively. The marked lag phase in the inhibition of root elongation and the release of organic acids implies that the expression of genes on the short arm of triticale chromosome 3R is induced by Al, and that these genes are necessary for the release of organic acids.
Biochemical Evidence for Two Novel Enzymes in the Biosynthesis of 3-Dimethylsulfoniopropionate in Spartina alterniflora1
Authors: Kocsis Michael G. , Hanson Andrew D. 
Published: July 2002

Abstract
3-Dimethylsulfoniopropionate (DMSP) is an osmoprotectant accumulated by the cordgrass Spartina alterniflora and other salt-tolerant plants. Previous in vivo isotope tracer and metabolic modeling studies demonstrated that S. alterniflora synthesizes DMSP via the routeS-methyl-Met → 3-dimethylsulfoniopropylamine (DMSP-amine) → 3-dimethylsulfoniopropionaldehyde → DMSP and indicated that the first reaction requires a far higher substrate concentration than the second to attain one-half-maximal rate. As neither of these reactions is known from other organisms, two novel enzymes are predicted. Two corresponding activities were identified inS. alterniflora leaf extracts using specific radioassays. The first, S-methyl-Met decarboxylase (SDC), strongly prefers the l-enantiomer ofS-methyl-Met, is pyridoxal 5′-phosphate-dependent, generates equimolar amounts of CO2 and DMSP-amine, and has a high apparent Km (approximately 18 mm) for its substrate. The second enzyme, DMSP-amine oxidase (DOX), requires O2 for activity, shows an apparentKm for DMSP-amine of 1.8 mm, and is not accompanied by DMSP-amine dehydrogenase or transaminase activity. Very little SDC or DOX activity was found in grasses lacking DMSP. These data indicate that SDC and DOX are the predicted novel enzymes of DMSP synthesis.
Interaction energies between β‐lactam antibiotics and E. coli penicillin‐binding protein 5 by reversible thermal denaturation
Authors: Beadle Beth M. , Nicholas Robert A. , Shoichet Brian K. 
Published: July 2002

AbstractPenicillin‐binding proteins (PBPs) catalyze the final stages of bacterial cell wall biosynthesis. PBPs form stable covalent complexes with β‐lactam antibiotics, leading to PBP inactivation and ultimately cell death. To understand more clearly how PBPs recognize β‐lactam antibiotics, it is important to know their energies of interaction. Because β‐lactam antibiotics bind covalently to PBPs, these energies are difficult to measure through binding equilibria. However, the noncovalent interaction energies between β‐lactam antibiotics and a PBP can be determined through reversible denaturation of enzyme–antibiotic complexes. Escherichia coli PBP 5, a d‐alanine carboxypeptidase, was reversibly denatured by temperature in an apparently two‐state manner with a temperature of melting (Tm) of 48.5°C and a van't Hoff enthalpy of unfolding (ΔHVH) of 193 kcal/mole. The binding of the β‐lactam antibiotics cefoxitin, cloxacillin, moxalactam, and imipenem all stabilized the enzyme significantly, with ΔTm values as high as +4.6°C (a noncovalent interaction energy of +2.7 kcal/mole). Interestingly, the noncovalent interaction energies of these ligands did not correlate with their second‐order acylation rate constants (k2/K′). These rate constants indicate the potency of a covalent inhibitor, but they appear to have little to do with interactions within covalent complexes, which is the state of the enzyme often used for structure‐based inhibitor design.
Improvement of Fatigue Strength of Aluminum Alloy by Cavitation
Shotless Peening
Authors: Soyama Hitoshi , Saito Kenichi , Saka Masumi 
Published: July 2002

Abstract
Cavitation impact, which normally produces severe damage in hydraulic machinery, can be used to modify surfaces in the same way as shot peening. Cavitation impact enables the surface of a material to be peened without the use of shot, thus it is called cavitation shotless peening. As there are no solid body collisions occurring in this peening process, the roughness of the peened surface should be less than that produced by shot peening. This characteristic makes it suitable for peening soft metals. In order to demonstrate the improvement of the fatigue strength of aluminum alloy by this process, specimens were subjected to the process, and then tested in a rotating bending fatigue test. Cavitation impacts were produced and controlled by using a submerged high speed water jet with cavitation, i.e., a cavitating jet. It was revealed that the fatigue strength of an aluminum alloy specimen treated by this peening process was 50% stronger than that of a specimen without peening.
Sexual Selection, Receiver Biases, and the Evolution of Sex Differences
Authors: Ryan Michael J. 
Published: July 2002

REVIEW
Recent approaches to analyzing the evolution of female mating preferences emphasize how historical influences on female receiver systems can bias the evolution of male traits that females find attractive. These studies combine animal behavior, sensory biology, phylogenetics, and artificial neural network models. They attempt to understand why specific phenotypes involved in sexual selection have evolved, rather than merely determining whether such traits and preferences are adaptive. It is now clear that traits and preferences often do not coevolve via genetic correlations, that female mating preferences for a given male trait are influenced by adaptations and constraints outside of the context of female responses to that particular trait, and that receiver biases can explain much of the diversity in male signaling phenotypes. It also appears that an understanding of historical effects will prove valuable in investigating why neural and cognitive systems respond to sensory stimuli as they do.
A Pharmacokinetic Study of Amphotericin B Lipid Complex Injection (Abelcet) in Patients with Definite or Probable Systemic Fungal Infections
Authors: Adedoyin Adedayo , Swenson Christine E. , Bolcsak Lois E. , Hellmann Andrzej , Radowska Danuta , Horwith Gary , Janoff Andrew S. , Branch Robert A. 
Published: July 2002

ABSTRACT
This study describes a pharmacokinetic evaluation of amphotericin B (AMB) lipid complex injection (ABLC or Abelcet) in 17 patients with systemic fungal infection administered 5 mg/kg of body weight/day by infusion for 10 to 17 days. The results showed that AMB exhibited multiexponential disposition with high clearance, large volume of distribution at steady state, and long apparent elimination half-life but no evidence of accumulation in the blood after multiple daily doses. The results confirm previous observations and further reinforce the suggestion that ABLC may exist as a depot in the tissues from which free AMB is slowly released to limit exposure.
Photoactive Porphyrin Derivative with Broad-Spectrum Activity against Oral Pathogens In Vitro
Authors: Rovaldi C. R. , Pievsky A. , Sole N. A. , Friden P. M. , Rothstein D. M. , Spacciapoli P. 
Published: July 2002

ABSTRACT

Photodynamic therapy (PDT) has historically been used as a means to treat cancerous tumors but has recently been used to kill bacterial cells through the use of targeted photosensitizers. PDT is a potential adjunct to scaling and root planing in the treatment of periodontal disease. However, the effectiveness of porphyrin derivatives against microorganisms has been limited because some gram-negative bacteria are refractory to photodynamic treatment with these agents. We have designed a porphyrin derivative conjugated to a pentalysine moeity that endows the molecule with activity against gram-positive and gram-negative bacteria. Whereas the porphyrin, chlorin e6, showed in vitro activity against a limited spectrum of bacteria, chlorin e6 conjugated to pentalysine showed in vitro activity against all oral microorganisms tested, including
Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum
subsp.
polymorphum, Actinomyces viscosus
, and the streptococci. Potent antimicrobial activity (≥5-log-unit reduction in the numbers of CFU per milliliter) was retained in the presence of up to 25% whole sheep blood. The use of potent, selective agents such as this chlorin e6–pentalysine conjugate to more effectively reduce the pathogenic bacteria in the periodontal pocket may be a significant tool for the treatment of periodontal disease.
pncA
Mutations as a Major Mechanism of Pyrazinamide Resistance in
Mycobacterium tuberculosis
: Spread of a Monoresistant Strain in Quebec, Canada
Authors: Cheng Shao-Ji , Thibert Louise , Sanchez Tracy , Heifets Leonid , Zhang Ying 
Published: July 2002

ABSTRACT

Pyrazinamide (PZA) is an important first-line tuberculosis drug that is part of the currently used short-course tuberculosis chemotherapy. PZA is a prodrug that has to be converted to the active form pyrazinoic acid by pyrazinamidase (PZase) activity, encoded by the
pncA
gene of
Mycobacterium tuberculosis
, and loss of PZase activity is associated with PZA resistance. To further define the genetic basis of PZA resistance and determine the frequency of PZA-resistant strains having
pncA
mutations, we sequenced the
pncA
gene from a panel of 59 PZA-resistant clinical isolates from Canada, the United States, and Korea. Two strains that did not contain
pncA
mutations and had positive PZase turned out to be falsely resistant. Three PZase-negative strains (MIC, >900 μg of PZA per ml) and one PZase-positive strain (strain 9739) (MIC, >300 μg of PZA per ml) did not have
pncA
mutations. The remaining 53 of the 57 PZA-resistant isolates had
pncA
mutations, confirming that
pncA
mutation is the major mechanism of PZA resistance. Various new and diverse mutations were found in the
pncA
gene. Interestingly, 20 PZA-monoresistant strains and 1 multidrug-resistant isolate from Quebec, Canada, all had the same
pncA
mutation profile, consisting of an 8-nucleotide deletion and an amino acid substitution of Arg140→Ser. Strain typing indicated that these strains are highly related and share almost identical IS
6110
patterns. These data strongly suggest the spread of a PZA-monoresistant strain, which has not previously been described.
Actinomycin Production Persists in a Strain of
Streptomyces antibioticus
Lacking Phenoxazinone Synthase
Authors: Jones George H. 
Published: July 2002

ABSTRACT

Truncated fragments of the phenoxazinone synthase gene,
phsA
, were prepared by the PCR. The resulting fragments were cloned into conjugative plasmid pKC1132 and transferred to
Streptomyces antibioticus
by conjugation from
Escherichia coli
. Two of the resulting constructs were integrated into the
S. antibioticus
chromosome by homologous recombination, and each of the resulting strains, designated 3720/pJSE173 and 3720/pJSE174, contained a disrupted
phsA
gene. Strain 3720/pJSE173 grew poorly, and Southern blotting suggested that genetic changes other than the disruption of the
phsA
gene might have occurred during the construction of that strain. Strain 3720/pJSE174 sporulated well and grew normally on the medium used to prepare inocula for antibiotic production. Strain 3720/pJSE174 also grew as well as the wild-type strain on antibiotic production medium containing either 1 or 5.7 mM phosphate. Strain 3720/pJSE174 was shown to be devoid of phenoxazinone synthase (PHS) activity, and PHS protein was undetectable in this strain by Western blotting. Despite the absence of detectable PHS activity, strain 3720/pJSE174 produced slightly more actinomycin than did the wild-type parent strain in medium containing 1 or 5.7 mM phosphate. The observation that strain 3720/pJSE174, lacking detectable PHS protein or enzyme activity, retained the ability to produce actinomycin supports the conclusion that PHS is not required for actinomycin biosynthesis in
S. antibioticus
.
Phenotypic Characterization of
pncA
Mutants of
Mycobacterium tuberculosis
Authors: Morlock Glenn P. , Crawford Jack T. , Butler W. Ray , Brim Suzanne E. , Sikes David , Mazurek Gerald H. , Woodley Charles L. , Cooksey Robert C. 
Published: July 2002

ABSTRACT

We examined the correlation of mutations in the pyrazinamidase (PZase) gene (
pncA
) with the pyrazinamide (PZA) resistance phenotype with 60
Mycobacterium tuberculosis
isolates. PZase activity was determined by the method of Wayne (L. G. Wayne, Am. Rev. Respir. Dis.
109:
147–151, 1974), and the entire
pncA
nucleotide sequence, including the 74 bp upstream of the start codon, was determined. PZA susceptibility testing was performed by the method of proportions on modified Middlebrook and Cohn 7H10 medium. The PZA MICs were ≥100 μg/ml for 37 isolates, 34 of which had alterations in the
pncA
gene. These mutations included missense substitutions for 24 isolates, nonsense substitutions for 3 isolates, frameshifts by deletion for 4 isolates, a three-codon insertion for 1 isolate, and putative regulatory mutations for 2 isolates. Among 21 isolates for which PZA MICs were <100 μg/ml, 3 had the same mutation (Thr47→Ala) and 18 had the wild-type sequence. For the three Thr47→Ala mutants PZA MICs were 12.5 μg/ml by the method of proportions on 7H10 agar; two of these were resistant to 100 μg of PZA per ml and the third was resistant to 800 μg of PZA per ml by the BACTEC method. In all, 30 different
pncA
mutations were found among the 37
pncA
mutants. No PZase activity was detected in 35 of 37 strains that were resistant to ≥100 μg of PZA per ml or in 34 of 37
pncA
mutants. Reduced PZase activity was found in the three mutants with the Thr47→Ala mutation. This study demonstrates that mutations in the
pncA
gene may serve as a reliable indicator of resistance to ≥100 μg of PZA per ml.
Comparison of Efficacies of RWJ-270201, Zanamivir, and Oseltamivir against H5N1, H9N2, and Other Avian Influenza Viruses
Authors: Govorkova Elena A. , Leneva Irina A. , Goloubeva Olga G. , Bush Karen , Webster Robert G. 
Published: July 2002

ABSTRACT
The orally administered neuraminidase (NA) inhibitor RWJ-270201 was tested in parallel with zanamivir and oseltamivir against a panel of avian influenza viruses for inhibition of NA activity and replication in tissue culture. The agents were then tested for protection of mice against lethal H5N1 and H9N2 virus infection. In vitro, RWJ-270201 was highly effective against all nine NA subtypes. NA inhibition by RWJ-270201 (50% inhibitory concentration, 0.9 to 4.3 nM) was superior to that by zanamivir and oseltamivir carboxylate. RWJ-270201 inhibited the replication of avian influenza viruses of both Eurasian and American lineages in MDCK cells (50% effective concentration, 0.5 to 11.8 μM). Mice given 10 mg of RWJ-270201 per kg of body weight per day were completely protected against lethal challenge with influenza A/Hong Kong/156/97 (H5N1) and A/quail/Hong Kong/G1/97 (H9N2) viruses. Both RWJ-270201 and oseltamivir significantly reduced virus titers in mouse lungs at daily dosages of 1.0 and 10 mg/kg and prevented the spread of virus to the brain. When treatment began 48 h after exposure to H5N1 virus, 10 mg of RWJ-270201/kg/day protected 50% of mice from death. These results suggest that RWJ-270201 is at least as effective as either zanamivir or oseltamivir against avian influenza viruses and may be of potential clinical use for treatment of emerging influenza viruses that may be transmitted from birds to humans.
Metallo-β-Lactamase Producers in Environmental Microbiota: New Molecular Class B Enzyme inJanthinobacterium lividum
Authors: Rossolini Gian Maria , Condemi Maria Adelaide , Pantanella Fabrizio , Docquier Jean-Denis , Amicosante Gianfranco , Thaller Maria Cristina 
Published: July 2002

ABSTRACTEleven environmental samples from different sources were screened for the presence of metallo-β-lactamase-producing bacteria by using a selective enrichment medium containing a carbapenem antibiotic and subsequently testing each isolate for production of EDTA-inhibitable carbapenemase activity. A total of 15 metallo-β-lactamase-producing isolates, including 10Stenotrophomonas maltophiliaisolates, 3Chryseobacteriumspp., oneAeromonas hydrophilaisolate, and oneJanthinobacterium lividumisolate (a species in which production of metallo-β-lactamase activity was not previously reported), were obtained from 8 samples. In theJ. lividumisolate, named JAC1, production of metallo-β-lactamase activity was elicited upon exposure to β-lactams. Screening of a JAC1 genomic library for clones showing a reduced imipenem susceptibility led to the isolation of a metallo-β-lactamase determinant encoding a new member (named THIN-B) of the highly divergent subclass B3 lineage of metallo-β-lactamases. THIN-B is most closely related (35.6% identical residues) to the L1 enzyme ofS. maltophiliaand more distantly related to the FEZ-1 enzyme ofLegionella gormanii(27.8% identity) and to the GOB-1 enzyme ofChryseobacterium meningosepticum(24.2% identity). Sequences related toblaTHIN-B, and inducible production of metallo-β-lactamase activity, were also detected in theJ. lividumtype strain DSM1522. Expression of theblaTHIN-Bgene inEscherichia coliresulted in decreased susceptibility to several β-lactams, including penicillins, cephalosporins (including cephamycins and oxyimino cephalosporins), and carbapenems, revealing a broad substrate specificity of the enzyme. The results of this study indicated that metallo-β-lactamase-producing bacteria are widespread in the environment and identified a new molecular class B enzyme in the environmental speciesJ. lividum.
Nosocomial Outbreak of Carbapenem-Resistant
Pseudomonas aeruginosa
with a New
bla
IMP
Allele,
bla
IMP-7
Authors: Gibb Alan Patrick , Tribuddharat Chanwit , Moore Richard A. , Louie Thomas J. , Krulicki Wally , Livermore David M. , Palepou Marie-France I. , Woodford Neil 
Published: July 2002

ABSTRACT

Pseudomonas aeruginosa
isolates from an outbreak in Canada were highly resistant to carbapenems and ceftazidime but not piperacillin. They produced a novel integron-associated metallo-β-lactamase, designated IMP-7, with 91% identity to IMP-1.
bla
IMP-7
was not detected with standard
bla
IMP
-specific primers, owing to mismatches in the forward primer.
Mutations Affecting the Rossman Fold of Isoleucyl-tRNA Synthetase Are Correlated with Low-Level Mupirocin Resistance in
Staphylococcus aureus
Authors: Antonio Martin , McFerran Neil , Pallen Mark J. 
Published: July 2002

ABSTRACT

The isoleucyl-tRNA synthetase (
ileS
) gene was sequenced in toto from 9 and in part from 31
Staphylococcus aureus
strains with various degrees of susceptibility to mupirocin. All strains for which the mupirocin MIC was greater than 8 μg/ml contained point mutations affecting the Rossman fold via Val-to-Phe changes at either residue 588 (V588F) or residue 631 (V631F). The importance of the V588F mutation was confirmed by an allele-specific PCR survey of 32 additional strains. Additional mutations of uncertain significance were found in residues clustered on the surface of the IleS protein.