bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dependency of Escherichia coli cell‐division size, and independency of nucleoid segregation on the mode and level of ftsZ expression
Authors: Palacios Pilar , Vicente Miguel , Sánchez Manuel 
Published: October 2006

Summary Expression of ftsZ in strain VIP205 is dissociated from its natural promoters, and is under the control of an inducible tac promoter. This abolishes the oscillation in ftsZ transcription observed in the wild type, allowing different levels of ftsZ expression. We demonstrate that this construction does not affect the expression of other genes, and has no effects on replication or nucleoid segregation. A shift in IPTG from 30 μM, that supports division at wild‐type sizes, to lower (6 μM) or higher (100μM) concentrations, indicates that VIP205 cells can divide within a broad range of FtsZ concentrations. Analysis of the morphological parameters during the transition from one IPTG concentration to another suggests that the correct timing of ftsZ expression, and the correct FtsZ concentration, are required for division to occur at normal cell sizes. After a transient division delay during the transition to lower IPTG concentrations, cells in which ftsZ is expressed continuously (yielding 80% of the wild‐type FtsZ levels) divide with the same division time as the wild type, but at the expense of becoming 1.5 times larger. A precise control of ftsZ expression is required for normal division, but the existence of additional regulators to maintain the correct timing during the cell cycle cannot be ruled out.
Differential binding of BvgA to two classes of virulence genes of Bordetella pertussis directs promoter selectivity by RNA polymerase
Authors: Zu Tao , Manetti Riccardo , Rappuoli Rino , Scarlato Vincenzo 
Published: October 2006

Summary Transcription of virulence genes of Bordetella pertussis is co‐ordinately regulated by the BvgA and BvgS proteins, which are members of the two‐component family of bacterial signal‐transduction proteins. BvgS is the transmembrane sensor and BvgA the transcriptional regulator. By gel mobility shift assays we demonstrate that phosphorylated BvgA (BvgAP) forms distinct complexes with the filamentous haemag‐glutinin (PFHA) promoter DNA at different BvgAP: DNA ratios. DNase I protection analyses show that phosphorylation of BvgA not only enhances affinity of the protein for the binding sites of the PFH and bvgP1 promoters, but it extends significantly the bound region towards position ‐35 of these promoters. Conversely, a 10‐fold higher amount of BvgAP is required for binding to a large DNA region, from ‐168 to ‐60, of the pertussis toxin (Ptox) promoter sequence. These findings suggest that the molecular interaction of BvgA P with the Ptox promoter is different from its interaction with the PFHA and bvgP1 promoters. The ß70Escherichia coli RNA polymerase (RNP) does not bind to the bug‐regulated promoters. However, following the formation of a BvgAP‐promoter complex, the E. coli RNP specifically recognizes and binds to the bvg‐regulated promoters. Thus, BvgAP exerts its action at the level of promoter recognition by directing promoter selectivity by RNP.
ERA, a novel cis‐acting element required for autoregulation and ethanol repression of PDC1 transcription in Saccharomyces cerevisiae
Authors: Liesen Thomas , Hollenberg Cornelis P. , Heinisch Jürgen J. 
Published: October 2006

Summary Yeast pyruvate decarboxylase (Pdc) catalyses the reaction at the branch‐point of fermentation and respiration. In this work we have investigated the mechanisms of its transcriptional regulation in response to glucose and the non‐fermentable carbon source ethanol. For this purpose we studied the function of different promoter fragments of PDC1, encoding the major pyruvate decarboxylase enzyme in wild‐type cells, in the basal CYC1 promoter context. Thus, we identified a sequence mediating the response to ethanol and provide evidence showing that transcription of PDC1 is controlled by ethanol repression rather than by glucose induction. Furthermore, we showed that the same sequence is responsible for an autoregulatory process, leading to increased transcription from both the PDC1 and the PDC5 promoters, in strains in which the genomic copy of PDC1 is deleted. In addition, we have confirmed the role of Rap1 binding and have demonstrated that the Gcr1 protein also acts in transcriptional activation. DNA‐protein interactions at the consensus Rap1 ‐binding site and the newly identified ethanol‐repression sequence (5 ‐AAATGC‐ATA‐3, termed 'ERA') were investigated by gel‐shift and footprint analyses. Both DNA‐binding activities were found in extracts from cells grown in media containing glucose or ethanol as the carbon source, indicating that the capacity to bind is not altered by the carbon source used.
Organizational characteristics and information content of an archaeal genome: 156kb of sequence from Sulfolobus solfataricus P2
Authors: Sensen C. W. , Klenk H.‐P. , Singh R. K. , Allard G. , Chan C. C.‐Y. , Liu Q. Y. , Penny S. L. , Young F. , Schenk M. E. , Gaasterland T. , Doolittle W. F. , Ragan M. A. , Charlebois R. L. 
Published: October 2006

SummaryWe have initiated a project to sequence the 3Mbp genome of the thermoacidophilic archaebacterium Sulfolobus solfataricus P2. Cosmids were selected from a provisional set of minimally overlapping clones, subcloned in pUC18, and sequenced using a hybrid (random plus directed) strategy to give two blocks of contiguous unique sequence, respectively, 100389 and 56105bp. These two contigs contain a total of 163 open reading frames (ORFs) in 26–29 putative operons; 56 ORFs could be identified with reasonable certainty. Clusters of ORFs potentially encode proteins of glycogen biosynthesis, oxidative decarboxylation of pyruvate, ATP‐dependent transport across membranes, isoprenoid biosynthesis, protein synthesis, and ribosomes. Putative promoters occur upstream of most ORFs. Thirty per cent of the predicted strong and medium‐strength promoters can initiate transcription at the start codon or within 10 nucleotides upstream, indicating a process of initial mRNA‐ribosome contact unlike that of most eubacterial genes. A novel termination motif is proposed to account for 15 additional terminations. The two contigs differ in densities of ORFs, insertion elements and repeated sequences; together they contain two copies of the previously reported insertion sequence ISC 1217, five additional IS elements representing four novel types, four classes of long non‐IS repeated sequences, and numerous short, perfect repeats.
Anti‐TNF Effects on Destructive Fibroblasts Depend on Mechanical Stress
Authors: Lange F. , Härtl S. , Ungethuem U. , Kuban R. J. , Hammerschmidt S. , Faber S. , Morawietz L. , Wirtz H. , Emmrich F. , Krenn V. , Sack U. 
Published: October 2006

AbstractJoint destruction in rheumatoid arthritis (RA) starts typically at sites of mechanically stressed inserts of the synovial membrane near the cartilage/bone border. In the therapy of RA, tumour necrosis factor (TNF) antagonists have rapidly emerged as a valuable class of anti‐rheumatic agents that reduce joint destruction. The aim of this study was to investigate and profile genes involved in the interaction between articular movement and anti‐TNF therapy in an in vitro model. Murine LS48 cells, an established substitute for invasive RA synovial fibroblasts, were cultured, stretched and/or treated with anti‐TNF‐α antibody for 24 h. RNA was isolated and gene transcript levels were determined using U74Av2 Affymetrix GeneChips to identify transcriptional events. Positive findings were verified by polymerase chain reaction (PCR). We identified 170 differentially regulated genes, including 44 of particular interest. Gene expression fell into different functional groups that can be explained by RA pathogenesis and experimental conditions. For 21 genes of the 44 of particular interest, regulation could be confirmed by real‐time PCR. Remarkably, we found structural as well as functional genes differently regulated between stretched cells, anti‐TNF‐treated cells, and stretched cells treated with anti‐TNF antibody. Additionally, we also found a large number of genes that are apparently not related to the experimental conditions. Mechanical exertion modulates gene expression and subsequently cellular response to anti‐TNF therapy. Results in exerted cells correspond to current knowledge regarding RA pathogenesis and underline the relevance of our experimental approach. Finally, the central function of the interleukin‐18 system in joint destruction could be confirmed by our findings.
Zeocin resistance as a dominant selective marker for transformation and targeted gene deletions in Candida glabrata
Authors: Alderton Alex J. , Burr Ian , Mühlschlegel Fritz A. , Tuite Mick F. 
Published: October 2006

SummaryMany of the genetic tools used to generate gene knockouts in Candida glabrata exploit auxotrophic markers but this is not suitable for use with clinical strains. Antibiotic resistance markers, however, allow one to target genes to be deleted without any prior genetic manipulation of clinical isolates. Such antibiotic selection markers have been widely reported for the manipulation of Saccharomyces cerevisiae. However, very few antibiotic resistance markers have been shown to be useful in C. glabrata. Here, we report the use of Zeocin resistance (ZeoR), encoded by the ble gene from Streptoalloteichus hindustanus, as a new positive selection marker for the genetic manipulation of C. glabrata including clinical strains that we show are significantly more sensitive to Zeocin than to G418. The potential of the ZeoR marker for targeted gene disruption in C. glabrata was confirmed by constructing deletions of the ADE2 in both a laboratory and a clinical strain of C. glabrata, using both short (90 bp) and long (400 bp) homology cassettes.
Yeast associated with human infections in south‐eastern Nigeria
Authors: Abia‐Bassey L. N. , Utsalo S. J. 
Published: October 2006

SummaryA total of 1921 specimens from nine clinical sources were examined by direct microscopy and culture to recover yeast associated with human infection. Identification of yeast was based on their carbon assimilation patterns, using API 20C AUX and ID 32 C (bioMérieux, France) commercial kits. A total of 178 specimens (9.3%) were positive for yeast. Most of the yeast isolates were recovered from urine samples and genital swabs. Prevalence was significantly higher in women (14.7%) than in men (1.4%) (P < 0.05). The age group 21–30 years recorded the highest prevalence of yeast infection (65.2%) followed by age group 11–20 years (16.9%) and >40 years (9.0%). When genital samples were considered, prevalence was significantly higher in the age group 21–30 years than that in older ones (P < 0.05). Isolates recovered included seven species of Candida and Trichosporon inkin. C. albicans accounted for the highest number of isolates (128) followed by C. tropicalis (23) and C. parapsilosis (9). Two isolates each of C. famata and C. norvegensis were recorded and are reported for the first time in Nigeria. The two isolates of T. inkin were recovered from perianal lesions and are also reported for the first time from Nigeria. C. albicans, C. glabrata, C. parapsilosis and C. krusei were found to be the most common yeast species that act as agents of human disease in south‐eastern Nigeria.
Tinea capitis among rural school children of the district of Magude, in Maputo province, Mozambique
Authors: Sidat Mohsin M. , Correia Della , Buene Titos P. 
Published: October 2006

SummaryThe study was carried out in two rural primary schools of the District of Magude, the largest district of Maputo Province in 2001. The prevalence of tinea capitis in each school was 11.6% (49/422) and 6.8% (18/263) and affected predominantly male children. The most common dermatophytes isolated from both schools were Microsporum audouinii. However, Trichophyton mentagrophytes was also found to be an important causal agent of tinea capitis in the District of Magude. Although the prevalence of tinea capitis found in our study is relatively high compared to previous cross‐sectional studies carried out in Mozambique, it is still closely related to the prevalence rates reported for African countries. Tinea capitis continues to be an important public health issue in Mozambique, particularly in primary school setting.
Detection of Candida species by PCR in self‐collected vaginal swabs of women after taking antibiotics
Authors: Tabrizi Sepehr N. , Pirotta Marie V. , Rudland Elice , Garland Suzanne M. 
Published: October 2006

SummaryWomen undergoing antibiotic treatment can develop vulvovaginal candidiasis. This study evaluated polymerase chain reaction (PCR) for the detection of Candida species in comparison with the conventional laboratory culture methods in samples from women with and without symptoms of postantibiotic candidiasis. The self‐collected vaginal swabs from 90 women, with no recent symptoms of vulvovaginal candidiasis (VVC), who were prescribed antibiotics for non‐genital infection were evaluated 8 days after completion of antibiotics and/or at the time of developing symptoms of VVC. Broad‐spectrum fungal PCR was performed on extracted DNA from each sample. Overall PCR detected four additional Canidida albicans, three Candida parapsilosis and one Candida tropicalis when compared with culture. All but one case additionally detected by PCR were found in patients with no VVC symptoms. PCR, although more sensitive than conventional culture methods, in this small number of cases, has not been able to detect Candida species in significantly more patients with symptoms suggestive of candidiasis. The results of this study may indicate that other agents including other yeast species may be responsible for symptoms of postantibiotic vulvovaginitis.
Role of the Blood‐Brain Barrier in the Formation of Long‐Chain ω‐3 and ω‐6 Fatty Acids from Essential Fatty Acid Precursors
Authors: Moore Steven A. , Yoder Elizabeth , Spector Arthur A. 
Published: October 2006

AbstractElongated, more highly polyunsaturated derivatives of linoleic acid (18:2ω‐6) and linolenic acid (18:3ω‐3) accumulate in brain, but their sites of synthesis and mechanism of entry are not well characterized. To investigate the role of the blood‐brain barrier in this process, cultured murine cere‐bromicrovascular endothelia were incubated with [1‐14C]18: 2ω‐6 or [1‐14C]18:3ω‐3 and their elongation/desaturation products determined. The major metabolite of 18:2ω‐6 was 20:4ω‐6, whereas the primary product from 18:3ω‐3 was 20: 5ω‐3. Although these products were found primarily in cell lipids, they were also released from the cells and gradually accumulated in the extracellular fluid. Eicosanoid production was observed from the 20:4ω‐6 and 20:5ω‐3 that were formed. No 22:5ω‐6 or 22:6ω‐3 fatty acids were detected, suggesting that these endothelial cells are not the site of the final desaturation step. Although the uptake of 18:3ω‐3 and 18:2ω‐6 was nearly identical, 18:3ω‐3 was more extensively elongated and desaturated. Competition experiments demonstrated a preference for 18:3ω‐3 by the elongation/desaturation pathway. These findings suggest that the blood‐brain barrier can play an important role in the elongation and desaturation of ω‐3 and ω‐6 essential fatty acids during their transfer from the circulation into the brain.
Demyelination Induced in Aggregating Brain Cell Cultures by a Monoclonal Antibody Against Myelin/Oligodendrocyte Glycoprotein
Authors: de Rosbo Nicole Kerlero , Honegger Paul , Lassmann Hans , Matthieu Jean‐Marie 
Published: October 2006

AbstractA monoclonal antibody (8–18C5) directed against myelin/oligodendrocyte glycoprotein (MOG) induced demyelination in aggregating brain cell cultures. With increasing doses of anti‐MOG antibody in the presence of complement, myelin basic protein (MBP) concentrations decreased in a dose‐related manner. A similar, albeit less pronounced, effect was observed on specific activity of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase. In the absence of complement, anti‐MOG antibody did not induce detectable demyelination. In contrast to the effect of anti‐MOG antibody and as expected, anti‐MBP antibody did not demyelinate aggregating brain cell cultures in the presence of complement. These results provide additional support to the suggestion that MOG, a quantitatively minor myelin component located on the external side of the myelin membrane, is a good target antigen for antibody‐induced demyelination. Indeed, they show that a purified anti‐MOG antibody directed against a single epitope on the glycoprotein can produce demyelination, not only in vivo as previously shown, but also in cultures. Such an observation has not been made with polyclonal antisera raised against purified myelin proteins like MBP and proteolipid protein, the major protein components of the myelin membrane, or myelin‐associated glycoprotein. These observations may have important implications regarding the possible role of anti‐MOG antibodies in demyelinating diseases.
Hexokinase Levels in Discrete Regions of Rat Brain: Evaluation by Quantitative Immuno fluoresence Using Interactive Laser Cytometry and Comparison with Basal Rates of Glucose Utilization
Authors: Burgess Robert W. , Wilson John E. 
Published: October 2006

AbstractRelative levels of hexokinase (ATP:D‐hexose 6‐phosphotransferase, EC 2.7.1.1) have been determined in 16 discrete regions of adult rat brain by a quantitative immunofluorescence method. The distribution of immunofluorescence in brain sections was determined by interactive laser cytometry and related to hexokinase content by comparison with standard sections containing known amounts of the enzyme. In many of these regions, referred to here as group I regions, hexokinase content was correlated with previously reported basal rates of glucose utilization. However, several regions (group II regions) in which hexokinase content exceeded that expected from basal rates of glucose utilization were also detected. Compared with the corresponding regions from albino rat brain, higher hexokinase levels were found in the dorsal and ventral lateral geniculate (group I regions) of pigmented Norway rate, a result reflecting previously reported increased glucose utilization by these regions in pigmented rats. There was no difference in hexokinase levels in the superior colliculus, a group II structure, from albino and pigmented rats, a finding implying that a reported increase in rate of glucose utilization in the superior colliculus of pigmented rats is effected without an increase in hexokinase content. It is suggested that group II regions may be adapted to sustain increases in rates of glucose utilization that are, relative to basal rates, considerably greater than those experienced by group I regions.
Phosphatidylcholine Asymmetry in Electroplax from the Electric Eel: Use of a Phosphatidylcholine Exchange Protein
Authors: Supernovich Carrie , Grain Richard , Rosenberg Philip 
Published: October 2006

AbstractPhosphatidylcholine asymmetry in the inner and outer leaflets of the plasma membrane bilayer of the innervated and noninnervated surfaces of the electroplax cell was determined, using a Phosphatidylcholine exchange protein. The exchange protein from bovine liver catalyzed the exchange of Phosphatidylcholine from small unilamellar vesicles to the outer monolayer of the plasma membrane bilayer. The exchange protein did not penetrate to the inner monolayer of the plasma membrane, did not modify the permeability of the electroplax, and did not alter the phospholipid or cholesterol content of the electroplax. In the innervated plasma membrane, 42% of the Phosphatidylcholine is in the outer leaflet, 33% is in the inner leaflet, and 25% is inaccessible to the exchange protein. Corresponding values for the noninnervated plasma membrane are 56, 26, and 18%, respectively. These results are similar to Phosphatidylcholine asymmetry in other biological membranes. This unique cell can be used as a model to test the effects on phospholipid asymmetry of compounds that act on the membrane.
Monoclonal Antibodies Against Myelin Proteolipid Protein: Identification and Characterization of Two Major Determinants
Authors: Yamamura Takashi , Konola Jukka T. , Wekerle Hartmut , Lees Marjorie B. 
Published: October 2006

ABSTRACT: This report describes the preparation and characterization of a panel of monoclonal antibodies (mAbs) against the myelin proteolipid protein (PLP). A Lewis rat was immunized with bovine proteolipid apoprotein and 27 mAbs were selected based on their reactivity against bovine PLP on enzyme‐linked immunosorbent assays. Eleven mAbs recognized the PLP carboxyl‐terminal sequence when tested against a panel of synthetic peptides in a solid‐phase assay. A carboxyl‐terminal pentapeptide (residues 272–276) was sufficient for antibody binding and the terminal phenylalanine residue was found particularly important. Deletion, modification, or replacement of this residue markedly reduced or obliterated antigen‐antibody interaction. Nine mAbs reacted with a second antigenic determinant, residues 209–217, but these could be identified only by competitive immunoassays. This peptide was a more effective inhibitor than the longer peptides 202–217 and 205–221, suggesting that flanking residues may interfere with peptide‐antibody interaction. Seven antibodies did not react with any of the synthetic peptides tested and their determinants remain unidentified. Immunoblot analysis showed that the mAbs reacted with both the PLP and the DM‐20 isoforms. Twenty‐three of the mAbs were of the immunoglobulin G2a or b isotype; the remaining antibodies were immunoglobulin M and all of these were specific for residues 209–217. Cultured murine oligodendrocytes were stained by most of the mAbs tested, but the most intense reactivity was observed with the carboxyl‐terminus‐specific mAbs. The immunocytochemical analyses demonstrate that the mAbs react with the native PLP in situ and show their potential usefulness for studies of the cell biology of myelin and oligodendrocytes.
Tellurium‐Induced Alterations in 3‐Hydroxy‐3‐Methylglutaryl‐CoA Reductase Gene Expression and Enzyme Activity: Differential Effects in Sciatic Nerve and Liver Suggest Tissue‐Specific Regulation of Cholesterol Synthesis
Authors: Toews A. D. , Goodrum J. F. , Lee S. Y. , Eckermann C. , Morell P. 
Published: October 2006

AbstractThe demyelination of peripheral nerves that results from exposure of developing rats to tellurium is due to inhibition of squalene epoxidase, a step in cholesterol biosynthesis. In sciatic nerve, cholesterol synthesis is greatly depressed, whereas in liver, some compensatory mechanism maintains normal levels of cholesterol synthesis. This tissue specificity was further explored by examining, in various tissues, gene expression and enzyme activity of 3‐hydroxy‐3‐methylglutaryl‐CoA reductase, the rate‐limiting enzyme in cholesterol biosynthesis. Exposure to tellurium resulted in pronounced increases in both message levels and enzyme activity in liver, the expected result consequent to up‐regulation of this enzyme in response to decreasing levels of intracellular sterols. In contrast to liver, levels of mRNA and enzyme activity in sciatic nerve were both decreased during the tellurium‐induced demyelinating period. The temporal pattern of changes in 3‐hydroxy‐3‐methylglutaryl‐CoA reductase message levels in sciatic nerve seen following exposure to tellurium was similar to the down‐regulation seen for mRNA specific for PNS myelin proteins. Possible mechanisms for differential control of cholesterol biosynthesis in sciatic nerve and liver are discussed.