Showing papers by "Public Health Research Institute published in 2004"
TL;DR: The current knowledge of DNA transport during transformation is reviewed, and proteins related to those involved in the assembly of type IV pili and type II secretion systems are reviewed.
Abstract: Naturally competent bacteria are able to take up exogenous DNA and undergo genetic transformation. The transport of DNA from the extracellular milieu into the cytoplasm is a complex process, and requires proteins that are related to those involved in the assembly of type IV pili and type II secretion systems, as well as a DNA translocase complex at the cytoplasmic membrane. Here, we will review the current knowledge of DNA transport during transformation.
745 citations
TL;DR: The identification and functional relevance of a highly biologically active lipid species—a polyketide synthase-derived phenolic glycolipid (PGL) produced by a subset of M. tuberculosis isolates belonging to the W-Beijing family that show ‘hyperlethality’ in murine disease models are described.
Abstract: Fifty million new infections with Mycobacterium tuberculosis occur annually, claiming 2-3 million lives from tuberculosis worldwide. Despite the apparent lack of significant genetic heterogeneity between strains of M. tuberculosis, there is mounting evidence that considerable heterogeneity exists in molecules important in disease pathogenesis. These differences may manifest in the ability of some isolates to modify the host cellular immune response, thereby contributing to the observed diversity of clinical outcomes. Here we describe the identification and functional relevance of a highly biologically active lipid species-a polyketide synthase-derived phenolic glycolipid (PGL) produced by a subset of M. tuberculosis isolates belonging to the W-Beijing family that show 'hyperlethality' in murine disease models. Disruption of PGL synthesis results in loss of this hypervirulent phenotype without significantly affecting bacterial load during disease. Loss of PGL was found to correlate with an increase in the release of the pro-inflammatory cytokines tumour-necrosis factor-alpha and interleukins 6 and 12 in vitro. Furthermore, the overproduction of PGL by M. tuberculosis or the addition of purified PGL to monocyte-derived macrophages was found to inhibit the release of these pro-inflammatory mediators in a dose-dependent manner.
705 citations
TL;DR: It is determined that S. aureus likely has a primarily clonal population structure and that spa typing can singly index genetic variation with 88% direct concordance with the microarray and can correctly assign isolates to phylogenetic lineages.
Abstract: Strain typing of microbial pathogens has two major aims: (i) to index genetic microvariation for use in outbreak investigations and (ii) to index genetic macrovariation for use in phylogenetic and population-based analyses. Until now, there has been no clear indication that one genetic marker can efficiently be used for both purposes. Previously, we had shown that DNA sequence analysis of the protein A gene variable repeat region (spa typing) provides a rapid and accurate method to discriminate Staphylococcus aureus outbreak isolates from those deemed epidemiologically unrelated. Here, using the hypothesis that the genetic macrovariation within a low-level recombinogenic species would accurately be characterized by a single-locus marker, we tested whether spa typing could congruently index the extensive genetic variation detected by a whole-genome DNA microarray in a collection of 36 isolates, which was recovered from 10 countries on four continents over a period of four decades, that is representative of the breadth of diversity within S. aureus. Using spa and coa typing, pulsed-field gel electrophoresis (PFGE), and microarray and multilocus enzyme electrophoresis (MLEE) data in molecular epidemiologic and evolutionary analyses, we determined that S. aureus likely has a primarily clonal population structure and that spa typing can singly index genetic variation with 88% direct concordance with the microarray and can correctly assign isolates to phylogenetic lineages. spa typing performed better than MLEE, PFGE, and coa typing in discriminatory power and in the degree of agreement with the microarray at various phylogenetic depths. This study showed that genetic analysis of the repeat region of protein A comprehensively characterizes both micro- and macrovariation in the primarily clonal population structure of S. aureus.
483 citations
TL;DR: The results suggested that the inherent neutralization resistance of JR-FL, and presumably of related primary isolates, is to a great extent mediated by gp120 V1/V2 domain structure rather than by sequence variations at the target sites.
Abstract: A major problem hampering the development of an effective vaccine against human immunodeficiency virus type 1 (HIV-1) is the resistance of many primary viral isolates to antibody-mediated neutralization. To identify factors responsible for this resistance, determinants of the large differences in neutralization sensitivities of HIV-1 pseudotyped with Env proteins derived from two prototypic clade B primary isolates were mapped. SF162 Env pseudotypes were neutralized very potently by a panel of sera from HIV-infected individuals, while JR-FL Env pseudotypes were neutralized by only a small fraction of these sera. This differential sensitivity to neutralization was also observed for a number of monoclonal antibodies (MAbs) directed against sites in the V2, V3, and CD4 binding domains, despite often similar binding affinities of these MAbs towards the two soluble rgp120s. The neutralization phenotypes were switched for chimeric Envs in which the V1/V2 domains of these two sequences were exchanged, indicating that the V1/V2 region regulated the overall neutralization sensitivity of these Envs. These results suggested that the inherent neutralization resistance of JR-FL, and presumably of related primary isolates, is to a great extent mediated by gp120 V1/V2 domain structure rather than by sequence variations at the target sites. Three MAbs (immunoglobulin G-b12, 2G12, and 2F5) previously reported to possess broad neutralizing activity for primary HIV-1 isolates neutralized JR-FL virus at least as well as SF162 virus and were not significantly affected by the V1/V2 domain exchanges. The rare antibodies capable of neutralizing a broad range of primary isolates thus appeared to be targeted to exceptional epitopes that are not sensitive to V1/V2 domain regulation of neutralization sensitivity.
265 citations
TL;DR: Campylobactor jejuni was isolacted from stool cultures from 14 of 46 partients with Guillain‐Barré syndrome and from 6 of healthy persons, and the difference was highly significant (P<0.0001); serological evidence of recent.
Abstract: Campylobacter jejuni was isolated from stool cultures from 14 (30%) of 46 patients with Guillain-Barre syndrome and from 6 (1.2%) of 503 healthy persons, and the difference was highly significant (p < 0.0001). In addition, serological evidence of recent C. jejuni infection was found in 5 of 29 patients with negative stool cultures. Therefore, 41% of patients were associated with C. jejuni infection. Ten of 12 (83%) isolates from patients with Guillain-Barre syndrome belonged to Penner serogroup 19, which is a rare serogroup in sporadic patients with C. jejuni enteritis. In the lectin typing study, all serogroup 19 strains from patients with Guillain-Barre syndrome were shown to contain terminal beta-N-acetylglucosamine residues on their cell surface, but serogroup 19 strains from patients with enteritis were not.
251 citations
TL;DR: The differential cytokine-chemokine response was mediated by extracted lipids, suggesting that these molecules regulate host responses to infection.
Abstract: In vitro infection of monocytes with Mycobacterium tuberculosis HN878 and related W/Beijing isolates preferentially induced interleukin-4 (IL-4) and IL-13, which characterize Th2 polarized immunity. In contrast, CDC1551 induced more IL-12 and other molecules associated with phagocyte activation and Th1 protective immunity. The differential cytokine-chemokine response was mediated by extracted lipids, suggesting that these molecules regulate host responses to infection.
232 citations
TL;DR: A standardized definition for the identification of M. tuberculosis strains belonging to the Beijing/W lineage, as described in this work, will facilitate further studies on the spread and characterization of this widespread genotype family of M., tuberculosis strains.
Abstract: Mycobacterium tuberculosis Beijing genotype strains are highly prevalent in Asian countries and in the territory of the former Soviet Union. They are increasingly reported in other areas of the world and are frequently associated with tuberculosis outbreaks and drug resistance. Beijing genotype strains, including W strains, have been characterized by their highly similar multicopy IS6110 restriction fragment length polymorphism (RFLP) patterns, deletion of spacers 1 to 34 in the direct repeat region (Beijing spoligotype), and insertion of IS6110 in the genomic dnaA-dnaN locus. In this study the suitability and comparability of these three genetic markers to identify members of the Beijing lineage were evaluated. In a well-characterized collection of 1,020 M. tuberculosis isolates representative of the IS6110 RFLP genotypes found in The Netherlands, strains of two clades had spoligotypes characteristic of the Beijing lineage. A set of 19 Beijing reference RFLP patterns was selected to retrieve all Beijing strains from the Dutch database. These reference patterns gave a sensitivity of 98.1% and a specificity of 99.7% for identifying Beijing strains (defined by spoligotyping) in an international database of 1,084 strains. The usefulness of the reference patterns was also assessed with large DNA fingerprint databases in two other European countries and for identification strains from the W lineage found in the United States. A standardized definition for the identification of M. tuberculosis strains belonging to the Beijing/W lineage, as described in this work, will facilitate further studies on the spread and characterization of this widespread genotype family of M. tuberculosis strains.
228 citations
TL;DR: The results of stroke cost studies provide insight into the distribution of the costs of stroke and the impact of stroke on the national expenditure on health care, with special attention to the allocation of resources among different health care facilities.
Abstract: Purpose— With the rapid international spread of interventions, there is a need to understand the economic implications of these changes and to interpret these economic implications on the international level. The purpose of this study is to systematically compare total health care expenditures on stroke, the costs of stroke per capita, and the distribution of stroke costs within different countries, with special attention to the allocation of resources among different health care facilities. Methods— Studies for this literature review were selected by conducting a literature search from January 1966 to July 2003. Key methodological, country-related, and monetary issues of the selected stroke cost studies were evaluated using a checklist. Results— After selection, 25 stroke cost studies were reviewed. Although the selected cost of illness studies used different methodologies, the estimated expenditures for stroke are approximately similar. The proportion of national health care in the 8 countries studied i...
226 citations
TL;DR: It is estimated that its etiologic agent, Mycobacterium tuberculosis, infects almost a third of the human population and kills two million people every year.
Abstract: Tuberculosis remains a worldwide threat despite the availability of the BCG vaccine and antibiotic treatment. It is estimated that its etiologic agent, Mycobacterium tuberculosis , infects almost a third of the human population and kills two million people every year ([27][1]). The recent human
215 citations
TL;DR: Asymptomatic PAOD is a significant predictor of cardiovascular morbidity and mortality among the elderly population and in high-risk subjects, measurement of the ABPI provides valuable information on future cardiovascular events.
199 citations
TL;DR: A novel bacterium that infects laboratory rats was isolated from wild Rattus norvegicus rats in Japan and it was revealed that the organism represents a novel clade in the family Anaplasmataceae, which includes the Schotti variant found in Ixodes ricinus ticks in the Netherlands and the Ehrlichia-like Rattus strain found in R. norveGicus rats from China.
Abstract: A novel bacterium that infects laboratory rats was isolated from wild Rattus norvegicus rats in Japan. Transmission electron microscopy of the spleen tissue revealed small cocci surrounded by an inner membrane and a thin, rippled outer membrane in a membrane-bound inclusion within the cytoplasm of endothelial cells. Phylogenetic analysis of the 16S rRNA gene sequence of the bacterium found in R. norvegicus rats and Ixodes ovatus ticks in Japan revealed that the organism represents a novel clade in the family Anaplasmataceae, which includes the Schotti variant found in Ixodes ricinus ticks in the Netherlands and the Ehrlichia-like Rattus strain found in R. norvegicus rats from China. The novel clade was confirmed by phylogenetic analysis of groESL sequences found in R. norvegicus rats and Ixodes ovatus ticks in Japan. No serological cross-reactivity was detected between this bacterium and members of the genera Anaplasma, Ehrlichia or Neorickettsia in the family Anaplasmataceae. It is proposed that this new cluster of bacteria should be designated ‘Candidatus Neoehrlichia mikurensis’.
TL;DR: The whole blood intracellular cytokine assay proved sensitive and specific for detecting mycobacteria-specific immunity 10 weeks after Bacillus Calmette-Guerin (BCG) vaccination of newborns from a rural field site.
TL;DR: The results demonstrate that nonmultiresistant hospital strains such as UK EMRSA-15 may be able to circulate in the community and could be mistaken for CMRSA based on their resistance profiles.
Abstract: Community methicillin-resistant Staphylococcus aureus (CMRSA) strains are being isolated with increasing frequency around the world. In Western Australia CMRSA are endemic in geographically remote communities and have been found to belong to five different contour-clamped homogeneous electric field (CHEF) electrophoretic patterns. Representatives of each of these CHEF patterns have been compared to CMRSA representative of CHEF patterns from other Australian states and New Zealand. With one exception, all of the isolates were nonmultiresistant and were not resistant to many antimicrobial agents other than the β-lactams. With one exception, which is not believed to be a CMRSA, all of the isolates harbored a β-lactamase plasmid. Erythromycin resistance was associated with a 2-kb plasmid. One of the β-lactamase plasmids was found to be able to acquire additional resistance determinants to become a multiple resistance plasmid. There were 10 multilocus sequence types belonging to eight distantly related clonal complexes of S. aureus. One new sequence type was found. Although most of the CMRSA harbored the type IVa SCCmec, a type IV structural variant was found and two new SCCmec types were identified. Protein A gene (spa) typing revealed two new spa types and, with two exceptions, corresponded to multilocus sequence typing. In contrast to other reports on CMRSA, most of the CMRSA strains studied here did not contain the Panton-Valentine leukocidin genes. The results also demonstrate that nonmultiresistant hospital strains such as UK EMRSA-15 may be able to circulate in the community and could be mistaken for CMRSA based on their resistance profiles.
TL;DR: Early in infection, differential expression of cytokines and cytokine receptors revealed that the mutant strain less efficiently suppresses key indicators of a Th1-type immune response, suggesting an immunomodulatory role for sulfatides in the pathogenesis of tuberculosis.
TL;DR: It is shown that ComEC contains an intramolecular disulphide bond in its N‐terminal extracellular loop (between the residues C131 and C172), which is required for the stability of the protein, and is probably introduced by BdbDC, a pair of competence‐induced oxidoreductase proteins.
Abstract: ComEC is a putative channel protein for DNA uptake in Bacillus subtilis and other genetically transformable bacteria. Membrane topology studies suggest a model of ComEC as a multispanning membrane protein with seven transmembrane segments (TMSs), and possibly with one laterally inserted amphipathic helix. We show that ComEC contains an intramolecular disulphide bond in its N-terminal extracellular loop (between the residues C131 and C172), which is required for the stability of the protein, and is probably introduced by BdbDC, a pair of competence-induced oxidoreductase proteins. By in vitro cross-linking using native cysteine residues we show that ComEC forms an oligomer. The oligomerization surface includes a transmembrane segment, TMS-G, near the cytoplasmic C-terminus of ComEC.
TL;DR: Nuclease-resistant, cytoplasmically resident molecular beacons were used to specifically label b-actin mRNA in living and motile chicken embryonic fibroblasts to enable further studies of the mechanism of b- actin mRNA localization, and will be useful for understanding the dynamics of mRNA distribution in other living cells.
TL;DR: The results suggest that overexpression of drug efflux pumps and/or selection of drug target site mutations are at least partially responsible for itraconazole resistance and could be considered mechanisms for the emergence of clinical resistance to this drug.
Abstract: We investigated the evolution of resistance to the antifungal drug itraconazole in replicate populations of Aspergillus fumigatus that were founded from a strain with a genotype of sensitivity to a single drug and then propagated under uniform conditions. For each population, conidia were serially transferred 10 times to agar medium either with or without itraconazole. After 10 transfers in medium supplemented with itraconazole, 10 itraconazole-resistant mutant strains were isolated from two populations. These mutant strains had different growth rates and different levels of itraconazole resistance. Analysis of the ergosterol contents of these mutants showed that they accumulate ergosterol when they are grown in the presence of itraconazole. The replacement of the CYP51A gene of the wild-type strain changed the susceptibility pattern of this strain to one of itraconazole resistance only when CYP51A genes with N22D and M220I mutations were used as selectable marker genes. Real-time quantitative reverse transcription-PCR was used to assess the levels of expression of the Afumdr1, Afumdr2, Afumdr3, Afumdr4, AtrF transporter, CYP51A, and CYP51B genes in these mutant strains. Most mutants showed either constitutive high-level expression or induction upon exposure of Afumdr3, Afumdr4, and AtrF to itraconazole. Our results suggest that overexpression of drug efflux pumps and/or selection of drug target site mutations are at least partially responsible for itraconazole resistance and could be considered mechanisms for the emergence of clinical resistance to this drug.
TL;DR: There appear to be differences between Nagoya and Uppsala with respect to both indoor and outdoor pollution levels of the measured pollutants.
TL;DR: The gyrB gene proved more highly differential than 16S, while, at the same time, as analytical as costly and laborious DNA:DNA hybridization techniques in differentiating species within the B. cereus group.
TL;DR: The role of patients in the feasibility of cardiovascular preventive care in general practice was explored by means of a qualitative study and patients' understanding of prevention of cardiovascular disease (CVD) was often insufficient.
TL;DR: Inter-observer agreement in cases with pneumonia was much worse than the agreement in negative (i.e. non-pneumonia) cases, and a general practitioner's selection of patients with a higher chance of having pneumonia for chest radiography would not improve the observer agreement.
TL;DR: Cigarettes smoked per day increased significantly in shift compared with daytime workers, and only for smoking, an unfavorable change was observed, which may explain, at most, only a part of the excess cardiovascular disease risk reported in shift workers.
Abstract: The purpose of the study was to investigate whether the reported increased cardiovascular disease risk in shift workers could be explained by changes in cardiovascular risk factors. In a cohort of 239 shift and 157 daytime workers, 1-year changes in biological and lifestyle cardiovascular risk factors were monitored between the start of a new job and 1 year later. Both body mass index and low-density lipoprotein/high-density lipoprotein cholesterol ratio decreased significantly in shift workers compared with daytime workers (body mass index change: -0.31 and +0.13 kg/m; low-density lipoprotein/high-density lipoprotein ratio change: -0.33 and -0.13 respectively). Cigarettes smoked per day increased significantly in shift compared with daytime workers (+1.42 and -1.03, respectively). Therefore, only for smoking, an unfavorable change was observed. This may explain, at most, only a part of the excess cardiovascular disease risk reported in shift workers.
Journal Article•
TL;DR: In this article, the differences between the immune systems of children and adults relevant to pediatric tuberculosis, M. tuberculosis-specific T-cell immunity in children, and potential application to immunodiagnostics and vaccine development are reviewed.
Abstract: Tuberculosis (TB) is one of the most important causes of infectious morbidity and mortality worldwide. Young children are more likely to develop severe disease from the causative agent Mycobacterium tuberculosis. These clinical observations likely reflect fundamental differences in the immune systems of young children and adults. Essential to effective TB immunity are functioning macrophages, dendritic cells, strong Th1-type T-cell immunity and a relative absence of Th2-type T-cell immunity. Critical differences between adults and children relevant to TB immunity include deficiencies in macrophage and dendritic cell function, deficiencies in the development of Th1-type T-cells in response to pathogens, and the propensity for infants and young children to develop Th2-type CD4+ T-cells in response to immunogens. In this article, knowledge about the requisite components of protective immunity, differences between the immune systems of children and adults relevant to pediatric tuberculosis, M. tuberculosis-specific T-cell immunity in children, and potential application to immunodiagnostics and vaccine development will be reviewed.
TL;DR: Biochemical and functional analyses of the isogenic mutant strain revealed a significant decrease in its abilities to cleave a chromogenic tripeptide substrate, acquire plasminogen from human plasma, and penetrate the extracellular matrix, which indicates that the last two C-terminal lysine residues of surface-exposed SEN contribute significantly to the plAsminogen-binding activity of intact group A streptococci and hence to their ability to exploit host properties to their own advantage
Abstract: Streptococcal surface enolase (SEN) is a major plasminogen-binding protein of group A streptococci. Our earlier biochemical studies have suggested that the region responsible for this property is likely located at the C-terminal end of the SEN molecule. In the present study, the gene encoding SEN was cloned from group A streptococci M6 isolate D471. A series of mutations in the sen gene corresponding to the C-terminal region (428KSFYNLKK435) of the SEN molecule were created by either deleting one or more terminal lysine residues or replacing them with leucine. All purified recombinant SEN proteins with altered C-terminal ends were found to be enzymatically active and were analyzed for their Glu- and Lys-plasminogen-binding activities. Wild-type SEN bound to Lys-plasminogen with almost three times more affinity than to Glu-plasminogen. However, the recombinant mutant SEN proteins with a deletion of Lys434-435 or with K435L and K434-435L replacements showed a significant decrease in Glu- and Lys-plasminogen-binding activities. Accordingly, a streptococcal mutant expressing SEN-K434-435L showed a significant decrease in Glu- and Lys-plasminogen-binding activities. Biochemical and functional analyses of the isogenic mutant strain revealed a significant decrease in its abilities to cleave a chromogenic tripeptide substrate, acquire plasminogen from human plasma, and penetrate the extracellular matrix. Together, these data indicate that the last two C-terminal lysine residues of surface-exposed SEN contribute significantly to the plasminogen-binding activity of intact group A streptococci and hence to their ability to exploit host properties to their own advantage in tissue invasion.
TL;DR: Results demonstrate that the V3 loop is accessible on the native virus envelope, that the strength of binding of anti-V3 Abs correlates with the potency of neutralization, that V3 epitopes may be shared rather than type specific, and that Abs against the V4 loop, particularly those targeting conformational epitopes, can mediate the neutralization of primary isolates.
Abstract: Antibodies (Abs) against the V3 loop of the human immunodeficiency virus type 1 gp120 envelope glycoprotein were initially considered to mediate only type-specific neutralization of T-cell-line-adapted viruses. However, recent data show that cross-neutralizing V3 Abs also exist, and primary isolates can be efficiently neutralized with anti-V3 monoclonal Abs (MAbs). The neutralizing activities of anti-V3 polyclonal Abs and MAbs may, however, be limited due to antigenic variations of the V3 region, a lack of V3 exposure on the surface of intact virions, or Ab specificity. For clarification of this issue, a panel of 32 human anti-V3 MAbs were screened for neutralization of an SF162-pseudotyped virus in a luciferase assay. MAbs selected with a V3 fusion protein whose V3 region mimics the conformation of the native virus were significantly more potent than MAbs selected with V3 peptides. Seven MAbs were further tested for neutralizing activity against 13 clade B viruses in a single-round peripheral blood mononuclear cell assay. While there was a spectrum of virus sensitivities to the anti-V3 MAbs observed, 12 of the 13 viruses were neutralized by one or more of the anti-V3 MAbs. MAb binding to intact virions correlated significantly with binding to solubilized gp120s and with the potency of neutralization. These results demonstrate that the V3 loop is accessible on the native virus envelope, that the strength of binding of anti-V3 Abs correlates with the potency of neutralization, that V3 epitopes may be shared rather than type specific, and that Abs against the V3 loop, particularly those targeting conformational epitopes, can mediate the neutralization of primary isolates.
TL;DR: Results do not support the use of adjunctive high-dose thalidomide therapy in the treatment of tuberculous meningitis and motor outcome after 6 months of antituberculosis therapy was similar in the two groups, even though the thalidmide group showed greater neurologic compromise on admission.
Abstract: Childhood tuberculous meningitis is associated with serious long-term sequelae, including mental retardation, behavior disturbances, and motor handicap. Brain damage in tuberculous meningitis results from a cytokine-mediated inflammatory response, which causes vasculitis and obstructive hydrocephalus. Thalidomide, a potent tumor necrosis factor alpha inhibitor, was well tolerated and possibly showed some clinical benefit in children with tuberculous meningitis during a pilot study. The purpose of the present study was to assess the effect of adjunctive thalidomide in addition to standard antituberculosis and corticosteroid therapy on the outcome of tuberculous meningitis. Thalidomide (24 mg/kg/day orally) or placebo was administered in a double-blind randomized fashion for 1 month to patients with stage 2 or 3 tuberculous meningitis. The study was terminated early because all adverse events and deaths occurred in one arm of the study (thalidomide group). Thirty of the 47 children enrolled received adjunctive thalidomide, of whom 6 (20%) developed a skin rash, 8 (26%) hepatitis, and 2 (6%) neutropenia or thrombocytopenia. Four deaths (13%) occurred in patients with very severe neurologic compromise at baseline; two deaths were associated with a rash. Motor outcome after 6 months of antituberculosis therapy was similar in the two groups, even though the thalidomide group showed greater neurologic compromise on admission. In addition, the mean IQ of the two treatment groups did not differ significantly (mean IQ thalidomide group 57.8 versus mean IQ control group 67.5; P = .16). These results do not support the use of adjunctive high-dose thalidomide therapy in the treatment of tuberculous meningitis.
TL;DR: The clinical outcome and patient satisfaction after implantation of monofocal and multifocal intraocular lenses was compared and success of both IOLs depends on preoperative expectations and postoperative quality of aided near vision.
TL;DR: Staphylococcus aureus remains an important human pathogen affecting both outpatients and those hospitalized and the time above the MPC(90) was significantly shorter for all agents.
TL;DR: In this paper, the authors used optical tweezers to demonstrate that the DNA transport machinery in Bacillus subtilis is a force-generating motor, and they found an uptake rate of 80 ± 10 bp s−1 that was forceindependent at external forces <40 pN, indicating that a powerful molecular machine supports DNA transport.
Abstract: Bacteria can acquire genetic diversity, including antibiotic resistance and virulence traits, by horizontal gene transfer. In particular, many bacteria are naturally competent for uptake of naked DNA from the environment in a process called transformation. Here, we used optical tweezers to demonstrate that the DNA transport machinery in Bacillus subtilis is a force-generating motor. Single DNA molecules were processively transported in a linear fashion without observable pausing events. Uncouplers inhibited DNA uptake immediately, suggesting that the transmembrane proton motive force is needed for DNA translocation. We found an uptake rate of 80 ± 10 bp s−1 that was force-independent at external forces <40 pN, indicating that a powerful molecular machine supports DNA transport.
TL;DR: Resistance mechanisms in fluconazole-resistant isolates of C. albicans isolated from AIDS patients from nine Brazilian hospitals include the presence of point mutations in the ERG11 gene and overexpression of ERG 11, and several genes encoding efflux pumps, as measured by quantitative real-time reverse transcriptase polymerase chain reaction.