bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Potassium on
Saccharomyces cerevisiae
Resistance to Fluconazole
Authors: Stella Carlos A. , Burgos Hilda I. 
Published: July 2002

ABSTRACT

Susceptibility of strain S288c of
Saccharomyces cerevisiae
to fluconazole was assayed in the presence and absence of KCl. Addition of 150 mM KCl renders the strain more sensitive to the antifungal agent. The effect is caused by the K
+
ion rather than the anion or the osmolarity of the medium. The increase in sensitivity does not modify the values of intracellular and extracellular pH established in the presence of KCl.
Inducible, but Not Constitutive, Resistance of Gonococci to Hydrophobic Agents Due to the MtrC-MtrD-MtrE Efflux Pump Requires TonB-ExbB-ExbD Proteins
Authors: Rouquette-Loughlin Corinne , Stojiljkovic Igor , Hrobowski Tara , Balthazar Jacqueline T. , Shafer William M. 
Published: July 2002

ABSTRACTThe MtrC-MtrD-MtrE efflux pump possessed byNeisseria gonorrhoeaeis very similar to the MexA-MexB-OprM efflux pump ofPseudomonas aeruginosa. Because the antimicrobial resistance property afforded by the MexA-MexB-OprM efflux pump also requires the TonB protein, we asked whether a similar requirement exists for the gonococcal efflux pump. Unlike earlier studies withP. aeruginosa, we found that constitutive levels of gonococcal resistance to hydrophobic antimicrobial agents (i.e., Triton X-100 [TX-100]) did not require the TonB, ExbB, or ExbD protein. However, inducible levels of TX-100 resistance in gonococci had an absolute requirement for the TonB-ExbB-ExbD system, suggesting that such resistance in gonococci has an energy requirement above and beyond that required for constitutive pump activity.
Behavioral Responses of
Rhodobacter sphaeroides
to Linear Gradients of the Nutrients Succinate and Acetate
Authors: Packer Helen L. , Armitage Judith P. 
Published: July 2002

ABSTRACT

Rhodobacter sphaeroides
cells were tethered by their flagella and subjected to increasing and decreasing nutrient gradients. Using motion analysis, changes in flagellar motor rotation were measured and the responses of the cells to the chemotactic gradients were determined. The steepness and concentration ranges of increasing and decreasing gradients were varied, and the bacterial responses were measured. This allowed the limits of gradients that would invoke changes in flagellar behavior to be determined and thus predicts the nature of gradients that would evoke chemotaxis in the environment. The sensory threshold was measured at 30 nM, and the response showed saturation at 150 μM. The study determined that cells detected and responded to changing concentration rates as low as 1 nM/s for acetate and 5 nM/s for succinate. The complex sensory system of
R. sphaeroides
responded to both increasing and decreasing concentration gradients of attractant with different sensitivities. In addition, transition phases involving changes in the motor speed and the smoothness of motor rotation were found.
Genetically Controlled Self-Aggregation of Cell-Surface-Engineered Yeast Responding to Glucose Concentration
Authors: Zou Wen , Ueda Mitsuyoshi , Tanaka Atsuo 
Published: July 2002

ABSTRACT

We constructed an arming (cell-surface-engineered) yeast displaying two types of agglutinin (modified a-agglutinin and α-agglutinin) on the cell surface, with agglutination being independent of both mating type and pheromones. The modified a-agglutinin was artificially prepared by the fusion of the genes encoding Aga1p and Aga2p. The modified a-agglutinin could induce agglutination of cells displaying Agα1p (α-agglutinin). The upstream region of the isocitrate lyase gene of
Candida tropicalis
(
UPR-ICL
), active at a low glucose concentration, was used as the promoter to express the modified a-agglutinin- and α-agglutinin-encoding genes. The arming yeast displaying both agglutinins agglutinated and sedimented in response to decreased glucose concentration. When the glucose concentration was high, the arming yeast grew normally. In the late log phase, when the glucose concentration became very low, agglutination occurred suddenly and drastically and yeast cells sedimented completely. Sedimentation was confirmed by weighing the aggregated cells after filtration of the broth. Strains in which aggregation can be genetically controlled can be used in industrial processes in which the separation of yeast cells from the supernatant is necessary.
Neurovirulence of Type 1 Polioviruses Isolated from Sewage in Japan
Authors: Horie Hitoshi , Yoshida Hiromu , Matsuura Kumiko , Miyazawa Miwako , Ota Yoshihiro , Nakayama Takashi , Doi Yutaka , Hashizume So 
Published: July 2002

ABSTRACT
Sixteen type 1 poliovirus strains were isolated from a sewage disposal plant located downstream of the Oyabe River in Japan between October 1993 and September 1995. The isolates were intratypically differentiated as vaccine-derived strains. Neutralizing antigenicity analysis with monoclonal antibodies and estimation of neurovirulence by mutant analysis by PCR and restriction enzyme cleavage (MAPREC) were performed for 13 type 1 strains of these isolates. The isolates were classified into three groups. Group I (five strains) had a variant type of antigenicity and neurovirulent phenotype. Group II (four strains) had the vaccine type of antigenicity and neurovirulent phenotype. Group III (four strains) had the vaccine type of antigenicity and an attenuated phenotype. Furthermore, it was demonstrated that the virulent isolates were neutralized by human sera obtained after oral poliomyelitis vaccine (OPV) administration, and the sera of rats immunized with inactivated poliovirus vaccine. Although vaccination was effective against virulent polioviruses, virulent viruses will continue to exist in the environment as long as OPV is in use.
Differentiation of
Phytophthora infestans
Sporangia from Other Airborne Biological Particles by Flow Cytometry
Authors: Day Jennifer P. , Kell Douglas B. , Griffith Gareth W. 
Published: July 2002

ABSTRACT

The ability of two different flow cytometers, the Microcyte (Optoflow) and the PAS-III (Partec), to differentiate sporangia of the late-blight pathogen
Phytophthora infestans
from other potential airborne particles was compared. With the PAS-III, light scatter and intrinsic fluorescence parameters could be used to differentiate sporangia from conidia of
Alternaria
or
Botrytis
spp., rust urediniospores, and pollen of grasses and plantain. Differentiation between
P. infestans
sporangia and powdery mildew conidia was not possible by these two methods but, when combined with analytical rules evolved by genetic programming methods, could be achieved after staining with the fluorescent brightener Calcofluor white M2R. The potential application of these techniques to the prediction of late-blight epiphytotics in the field is discussed.
Genomic Sequence and Evolution of Marine Cyanophage P60: a New Insight on Lytic and Lysogenic Phages
Authors: Chen Feng , Lu Jingrang 
Published: July 2002

ABSTRACT

The genome of cyanophage P60, a lytic virus which infects marine
Synechococcus
WH7803, was completely sequenced. The P60 genome contained 47,872 bp with 80 potential open reading frames that were mostly similar to the genes found in lytic phages like T7, phi-YeO3-12, and SIO1. The DNA replication system, consisting of primase-helicase and DNA polymerase, appeared to be more conserved in podoviruses than in siphoviruses and myoviruses, suggesting that DNA replication genes could be the critical elements for lytic phages. Strikingly high sequence similarities in the regions coding for nucleotide metabolism were found between cyanophage P60 and marine unicellular cyanobacteria.
Comparative Analysis of Human Cytomegalovirus-Specific CD4
+
T-Cell Frequency and Lymphoproliferative Response in Human Immunodeficiency Virus-Positive Patients
Authors: Piccinini Giampiero , Comolli Giuditta , Genini Emilia , Lilleri Daniele , Gulminetti Roberto , Maccario Rita , Revello Maria Grazia , Gerna Giuseppe 
Published: July 2002

ABSTRACT

Evaluation of human cytomegalovirus (HCMV)-specific T-helper immunity could contribute in optimizing anti-HCMV therapy in human immunodeficiency virus (HIV)-infected patients. Testin the lymphoproliferative response (LPR) is the standard technique used to evaluate T-helper response, but its use in the routine diagnostic laboratory setting can be problematic. The most promising new alternative technique is the determination of HCMV-specific CD4
+
T-cell frequency by flow cytometry detection of intracellular cytokine production after short-term antigen-specific activation of peripheral blood mononuclear cells. HCMV-specific LPR and CD4
+
T-cell frequency were compared in a group of 78 blood samples from 65 HIV-infected patients. The results showed concordance in 80.7% of samples. In addition, comparative analysis of sequential blood samples from 13 HIV-infected patients showed that while in about half of patients the T-helper HCMV-specific immune response remained stable during highly active antiretroviral therapy (HAART), in the other half declining levels of the HCMV-specific CD4
+
-mediated immune response were determined by either one or both assays. In conclusion, our data suggest that the determination of HCMV-specific CD4
+
T-cell frequency can be considered a valuable alternative to the LPR test for the detection of HCMV-specific T-helper response in HIV-infected patients. It could facilitate wider screening of anti-HCMV T-helper activity in HIV-infected patients, with potential benefits for clinicians in deciding strategies of discontinuation or maintenance of anti-HCMV therapy.
Insecticide-Treated Bed Nets Reduce Plasma Antibody Levels and Limit the Repertoire of Antibodies to
Plasmodium falciparum
Variant Surface Antigens
Authors: Askjaer Nikolaj , Maxwell Caroline , Chambo William , Staalsoe Trine , Nielsen Morten , Hviid Lars , Curtis Chris , Theander Thor G. 
Published: July 2002

ABSTRACT

The use of insecticide-treated bed nets (ITN) has been documented to reduce malaria morbidity and mortality in areas with endemic malaria, but concerns have been raised that ITN usage could affect the acquisition of malaria immunity. Several lines of evidence have indicated that antibodies against variant surface antigens (VSA) are important in the development of naturally acquired immunity to
Plasmodium falciparum
malaria and may thus be good indicators of immune status. We have compared the levels of VSA antibodies in plasma from children who have used ITN for 4 years to levels in plasma from children from a nearby village not using ITN. A total of 97 plasma samples were analyzed using 13 different
P. falciparum
isolates. We found that the children using ITN had significantly lower VSA antibody levels and recognized a smaller proportion of the VSA expressed by the tested parasite isolates than children not using ITN.
fbpABC
Gene Cluster in
Neisseria meningitidis
Is Transcribed as an Operon
Authors: Khun Heng H. , Deved Vinay , Wong Howard , Lee B. Craig 
Published: July 2002

ABSTRACT

The neisserial
fbpABC
locus has been proposed to constitute a single transcriptional unit. To confirm this operonic arrangement, transcription assays using reverse transcriptase PCR amplification were conducted with
Neisseria meningitidis
. The presence of
fbpAB
and
fbpBC
transcripts obtained by priming cDNA synthesis with an
fbpC
-sequence-specific oligonucleotide indicates that
fbpABC
is organized as a single expression unit. The ratio of
fbpA
to
fbpABC
mRNA was approximately between 10- to 20-fold, as determined by real-time quantitative PCR.
Macropinocytosis as a Mechanism of Entry into Primary Human Urethral Epithelial Cells by
Neisseria gonorrhoeae
Authors: Zenni Michael K. , Giardina Peter C. , Harvey Hillery A. , Shao Jianqiang , Ketterer Margaret R. , Lubaroff David M. , Williams Richard D. , Apicella Michael A. 
Published: July 2002

ABSTRACT

Gonococcal entry into primary human urethral epithelial cells (HUEC) can occur by macropinocytosis. Scanning and transmission electron microscopy revealed lamellipodia surrounding gonococci, and confocal laser scanning microscopy analysis showed organisms colocalized with
M
r
70,000 fluorescein isothiocyanate-labeled dextran within the cells. Phosphoinositide 3-kinase inhibitors and an actin polymerization inhibitor prevented macropinocytic entry of gonococci into HUEC.
Are B Lymphocytes of Importance in SevereStaphylococcus aureusInfections?
Authors: Gjertsson Inger , Hultgren Olof Hörnquist , Stenson Martin , Holmdahl Rikard , Tarkowski Andrzej 
Published: July 2002

ABSTRACTTo investigate the role of B cells in experimental, superantigen-mediatedStaphylococcus aureusarthritis and sepsis, we used gene-targeted B-cell-deficient mice. The mice were inoculated intravenously with a toxic shock syndrome toxin 1 (TSST-1)-producingS. aureusstrain. The B-cell-deficient and thus agamma-globulinemic mice showed striking similarities to the wild-type control animals with respect to the development of arthritis, the mortality rate, and the rate of bacterial clearance. Surprisingly, we found that the levels of gamma interferon in serum were significantly lower (P< 0.0001) in B-cell-deficient mice than in the controls, possibly due to impaired superantigen presentation and a diminished expression of costimulatory molecules. In contrast, the levels of interleukin-4 (IL-4), IL-6, and IL-10 in serum were equal in both groups. Our findings demonstrate that neither mature B cells nor their products significantly contribute to the course ofS. aureus-induced septic arthritis.
Host and Tissue Specificity of
Trichomonas vaginalis
Is Not Mediated by Its Known Adhesion Proteins
Authors: Addis Maria Filippa , Rappelli Paola , Fiori Pier Luigi 
Published: July 2002

ABSTRACT

Adhesion of
Trichomonas vaginalis
is believed to be dependent on four adhesion proteins, which are thought to bind to vaginal epithelial cells in a specific manner with a ligand-receptor type of interaction. However, the specific receptors on the host cell have not yet been identified. In this work, the ability of the
T. vaginalis
adhesins to bind to cells of different histologic derivations and from different species has been studied. HeLa, CHO, and Vero cell lines; erythrocytes from different species; and a prokaryote without a cell wall,
Mycoplasma hominis
, were employed in order to investigate the cell specificity of the
T. vaginalis
adhesins. We observed that the
T. vaginalis
adhesins are able to bind to the different cell types to the same extent, suggesting that the host and tissue specificity of
T. vaginalis
adhesion should not be due to specificity of the parasite adhesins. Our results suggest that the data published to date on the subject are probably artifactual and that the experiments reported in the literature are not appropriate for identification of protozoan adhesins.
Epitope Mapping of Monoclonal Antibodies Capable of Neutralizing Cytotoxic Necrotizing Factor Type 1 of Uropathogenic
Escherichia coli
Authors: Meysick K. C. , Mills M. , O'Brien A. D. 
Published: July 2002

ABSTRACT

Cytotoxic necrotizing factor type 1 (CNF1) of uropathogenic
Escherichia coli
belongs to a family of bacterial toxins that target the small GTP-binding Rho proteins that regulate the actin cytoskeleton. Members of this toxin family typically inactivate Rho; however, CNF1 and the highly related CNF2 activate Rho by deamidation. Other investigators have reported that the first 190 amino acids of CNF1 constitute the cellular binding domain and that the CNF1 enzymatic domain lies within a 300-amino-acid stretch in the C terminus of the toxin. Amino acids 53 to 75 appear to be critical for cell receptor recognition, while amino acids Cys866 and His881 are considered essential for deamidation activity. To delineate further the functional domains of CNF1, we generated 16 monoclonal antibodies (MAbs) against the toxin and used them for epitope mapping studies. Based on Western blot immunoreactivity patterns obtained from a series of truncated CNF1 proteins, this panel of MAbs mapped to epitopes located throughout the toxin, including the binding and enzymatic domains. All MAbs showed reactivity to CNF1 by Western and dot blot analyses. However, only 7 of the 16 MAbs exhibited cross-reactivity with CNF2. Furthermore, only three MAbs demonstrated the capacity to neutralize toxin in either HEp-2 cell assays (inhibition of multinucleation) or 5637 bladder cell assays (inhibition of cytotoxicity). Since CNF1 epitopes recognized by neutralizing MAbs are likely to represent domains or regions necessary for the biological activities of the toxin, the epitopes recognized by these three MAbs, designated JC4 (immunoglobulin G2a [IgG2a]), BF8 (IgA), and NG8 (IgG2a), were more precisely defined. MAbs JC4 and BF8 reacted with epitopes that were common to CNF1 and CNF2 and located within the putative CNF1 binding domain. MAb JC4 recognized an epitope spanning amino acids 169 to 191, whereas MAb BF8 mapped to an epitope between amino acids 135 and 164. Despite the capacity of both MAbs to recognize CNF2 in Western blot analyses, only MAb BF8 neutralized CNF2. MAb NG8 showed reactivity to a CNF1-specific epitope located between amino acids 683 and 730, a region that includes a very small portion of the putative enzymatic domain. Taken together, these findings identify three new regions of the toxin that appear to be critical for the biological activity of CNF1.
Activation of Extracellular Signal-Related Protein Kinases 1 and 2 of the Mitogen-Activated Protein Kinase Family by Lipopolysaccharide Requires Plasma in Neutrophils from Adults and Newborns
Authors: Bonner S. , Yan S. R. , Byers D. M. , Bortolussi R. 
Published: July 2002

ABSTRACTNeutrophils exposed to low concentrations of gram-negative lipopolysaccharide (LPS) become primed and have an increased oxidative response to a second stimulus (e.g., formyl-methionyl-leucyl-phenylalanine [fMLP]). In studies aimed at understanding newborn sepsis, we have shown that neutrophils of newborns are not primed in response to LPS. To further understand the processes involved in LPS-mediated priming of neutrophils, we explored the role of extracellular signal-related protein kinases (ERK 1 and 2) of the mitogen-activated protein kinase family. We found that LPS activated ERK 1 and 2 in cells of both adults and newborns and that activation was plasma dependent (maximal at ≥5%) through LPS-binding protein. Although fibronectin in plasma is required for LPS-mediated priming of neutrophils of adults assessed by fMLP-triggered oxidative burst, it was not required for LPS-mediated activation of ERK 1 and 2. LPS-mediated activation was dose and time dependent; maximal activation occurred with approximately 5 ng of LPS per ml and at 10 to 40 min. We used the inhibitor PD 98059 to study the role of ERK 1 and 2 in the LPS-primed fMLP-triggered oxidative burst. While Western blotting showed that 100 μM PD 98059 completely inhibited LPS-mediated ERK activation, oxidative response to fMLP by a chemiluminescence assay revealed that the same concentration inhibited the LPS-primed oxidative burst by only 40%. We conclude that in neutrophils, LPS-mediated activation of ERK 1 and 2 requires plasma and that this activation is not dependent on fibronectin. In addition, we found that the ERK pathway is not responsible for the lack of LPS priming in neutrophils of newborns but may be required for 40% of the LPS-primed fMLP-triggered oxidative burst in cells of adults.
Induction of Protective Immunity toListeria monocytogenesby Immunization with Plasmid DNA Expressing a Helper T-Cell Epitope That Replaces the Class II-Associated Invariant Chain Peptide of the Invariant Chain
Authors: Nagata Toshi , Aoshi Taiki , Suzuki Mina , Uchijima Masato , Kim Yeung-Hyen , Yang Zhibo , Koide Yukio 
Published: July 2002

ABSTRACTListeriaepitope-specific helper T (Th) cells were able to be primed and induced in vivo by immunization with a plasmid carrying an invariant chain (Ii) gene whose class II-associated invariant chain peptide (CLIP) region was replaced by aListeriaTh epitope. Immunization of C3H/He mice with an Ii-LLO 215-226 plasmid induced specific interferon-γ- and interleukin 2-producing Th cells and conferred significant protective immunity against listerial infection.
Transcriptional and Mutational Analyses of theStreptomyces lividans recXGene and Its Interference with RecA Activity
Authors: Vierling Silke , Weber Tilmann , Wohlleben Wolfgang , Muth Günther 
Published: July 2002

ABSTRACTThe role of the 20,922-Da RecX protein and its interference with RecA activity were analyzed inStreptomyces lividans. TherecXgene is located 220 bp downstream ofrecA. Transcriptional analysis by reverse transcriptase PCR demonstrated thatrecXandrecAconstitute an operon. WhilerecAwas transcribed at a basal level even under noninducing conditions, arecA-recXcotranscript was only detectable after induction ofrecAfollowing DNA damage. TherecA-recXcotranscript was less abundant than therecAtranscript alone. TherecXgene was inactivated by gene replacement. The resulting mutant had a clearly diminished colony size, but was not impaired in recombination activity, genetic instability, and resistance against UV irradiation. Expression of an extra copy of theS. lividans recAgene under control of the thiostrepton-inducibletipApromoter was lethal to therecXmutant, demonstrating that RecX is required to overcome the toxic effects ofrecAoverexpression. Since inactivation of therecXgene did not influence transcription ofrecA, the putative function of the RecX protein might be the downregulation of RecA activity by interaction with the RecA protein or filament.
A Gene Cluster for the Mevalonate Pathway from
Streptomyces
sp. Strain CL190
Authors: Takagi Motoki , Kuzuyama Tomohisa , Takahashi Shunji , Seto Haruo 
Published: July 2002

ABSTRACT

A biosynthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC
1.1.1.34
), the rate-limiting enzyme of the mevalonate pathway for isopentenyl diphosphate biosynthesis, had previously been purified from
Streptomyces
sp. strain CL190 and its corresponding gene (
hmgr
) had been cloned (S. Takahashi, T. Kuzuyama, and H. Seto, J. Bacteriol. 181:1256–1263, 1999). Sequence analysis of the flanking regions of the
hmgr
gene revealed five new open reading frames,
orfA
to -
E
, which showed similarity to those encoding eucaryotic and archaebacterial enzymes for the mevalonate pathway. Feeding experiments with [1-
13
C]acetate demonstrated that
Escherichia coli
JM109 harboring the
hmgr
gene and these open reading frames used the mevalonate pathway under induction with isopropyl β-
d
-thiogalactopyranoside. This transformant could grow in the presence of fosmidomycin, a potent and specific inhibitor of the nonmevalonate pathway, indicating that the mevalonate pathway, intrinsically absent in
E. coli
, is operating in the
E. coli
transformant. The
hmgr
gene and
orfABCDE
are thus unambiguously shown to be responsible for the mevalonate pathway and to form a gene cluster in the genome of
Streptomyces
sp. strain CL190.
Identification of an Ancillary Protein, YabF, Required for Activity of the KefC Glutathione-Gated Potassium Efflux System in
Escherichia coli
Authors: Miller S. , Ness L. S. , Wood C. M. , Fox B. C. , Booth I. R. 
Published: July 2002

ABSTRACT

A new subunit, YabF, for the KefC K
+
efflux system in
Escherichia coli
has been identified. The subunit is required for maximum activity of KefC. Deletion of
yabF
reduces KefC activity 10-fold, and supply of YabF in
trans
restores activity. IS
2
and IS
10
R insertions in
yabF
can be isolated as suppressors of KefC activity consequent upon the V427A and D264A KefC mutations.