EPIDEMIOLOGICAL STATUS OF EXTENDED SPECTRUM BETALACTAMASE PRODUCING Klebsiella pneumoniae IN SUB-SAHARIAN AFRICA (MALI) IN INTERNATIONAL ADOPTION

Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011

Portrait of Candida albicans Adherence Regulators

Cell-substrate adherence is a fundamental property of microorganisms that enables them to exist in biofilms. Our study focuses on adherence of the fungal pathogen Candida albicans to one substrate, silicone, that is relevant to device-associated infection. We conducted a mutant screen with a quantitative flow-cell assay to identify thirty transcription factors that are required for adherence. We then combined nanoString gene expression profiling with functional analysis to elucidate relationships among these transcription factors, with two major goals: to extend our understanding of transcription factors previously known to govern adherence or biofilm formation, and to gain insight into the many transcription factors we identified that were relatively uncharacterized, particularly in the context of adherence or cell surface biogenesis. With regard to the first goal, we have discovered a role for biofilm regulator Bcr1 in adherence, and found that biofilm regulator Ace2 is a major functional target of chromatin remodeling factor Snf5. In addition, Bcr1 and Ace2 share several target genes, pointing to a new connection between them. With regard to the second goal, our findings reveal existence of a large regulatory network that connects eleven adherence regulators, the zinc-response regulator Zap1, and approximately one quarter of the predicted cell surface protein genes in this organism. This limited yet sensitive glimpse of mutant gene expression changes had thus defined one of the broadest cell surface regulatory networks in C. albicans

Identification of proteins associated with the yeast mitochondrial RNA polymerase by tandem affinity purification

The abundance of mitochondrial (mt) transcripts varies under different conditions, and is thought to depend upon rates of transcription initiation, transcription termination/attenuation and RNA processing/degradation. The requirement to maintain the balance between RNA synthesis and processing may involve coordination between these processes; however, little is known about factors that regulate the activity of mtRNA polymerase (mtRNAP). Recent attempts to identify mtRNAP–protein interactions in yeast by means of a generalized tandem affinity purification (TAP) protocol were not successful, most likely because they involved a C-terminal mtRNAP–TAP fusion (which is incompatible with mtRNAP function) and because of the use of whole-cell solubilization protocols that did not preserve the integrity of mt protein complexes. Based upon the structure of T7 RNAP (to which mtRNAPs show high sequence similarity), we identified positions in yeast mtRNAP that allow insertion of a small affinity tag, confirmed the mature N-terminus, constructed a functional N-terminal TAP–mtRNAP fusion, pulled down associated proteins, and identified them by LC–MS–MS. Among the proteins found in the pull-down were a DEAD-box protein (Mss116p) and an RNA-binding protein (Pet127p). Previous genetic experiments suggested a role for these proteins in linking transcription and RNA degradation, in that a defect in the mt degradadosome could be suppressed by overexpression of either of these proteins or, independently, by mutations in either mtRNAP or its initiation factor Mtf1p. Further, we found that Mss116p inhibits transcription by mtRNAP in vitro in a steady-state reaction. Our results support the hypothesis that Mss116p and Pet127p are involved in modulation of mtRNAP activity. Copyright © 2009 John Wiley & Sons, Ltd

Inter-Species Complementation of the Translocon Beta Subunit Requires Only Its Transmembrane Domain

In eukaryotes, proteins enter the secretory pathway through the translocon pore of the endoplasmic reticulum. This protein translocation channel is composed of three major subunits, called Sec61α, β and γ in mammals. Unlike the other subunits, the β subunit is dispensable for translocation and cell viability in all organisms studied. Intriguingly, the knockout of the Sec61β encoding genes results in different phenotypes in different species. Nevertheless, the β subunit shows a high level of sequence homology across species, suggesting the conservation of a biological function that remains ill-defined. To address its cellular roles, we characterized the homolog of Sec61β in the fission yeast Schizosaccharomyces pombe (Sbh1p). Here, we show that the knockout of sbh1+ results in severe cold sensitivity, increased sensitivity to cell-wall stress, and reduced protein secretion at 23°C. Sec61β homologs from Saccharomyces cerevisiae and human complement the knockout of sbh1+ in S. pombe. As in S. cerevisiae, the transmembrane domain (TMD) of S. pombe Sec61β is sufficient to complement the phenotypes resulting from the knockout of the entire encoding gene. Remarkably, the TMD of Sec61β from S. cerevisiae and human also complement the gene knockouts in both yeasts. Together, these observations indicate that the TMD of Sec61β exerts a cellular function that is conserved across species

Inter-Species Complementation of the Translocon Beta Subunit Requires Only Its Transmembrane Domain

In eukaryotes, proteins enter the secretory pathway through the translocon pore of the endoplasmic reticulum. This protein translocation channel is composed of three major subunits, called Sec61α, β and γ in mammals. Unlike the other subunits, the β subunit is dispensable for translocation and cell viability in all organisms studied. Intriguingly, the knockout of the Sec61β encoding genes results in different phenotypes in different species. Nevertheless, the β subunit shows a high level of sequence homology across species, suggesting the conservation of a biological function that remains ill-defined. To address its cellular roles, we characterized the homolog of Sec61β in the fission yeast Schizosaccharomyces pombe (Sbh1p). Here, we show that the knockout of sbh1+ results in severe cold sensitivity, increased sensitivity to cell-wall stress, and reduced protein secretion at 23°C. Sec61β homologs from Saccharomyces cerevisiae and human complement the knockout of sbh1+ in S. pombe. As in S. cerevisiae, the transmembrane domain (TMD) of S. pombe Sec61β is sufficient to complement the phenotypes resulting from the knockout of the entire encoding gene. Remarkably, the TMD of Sec61β from S. cerevisiae and human also complement the gene knockouts in both yeasts. Together, these observations indicate that the TMD of Sec61β exerts a cellular function that is conserved across species

Genetic markers associated with resistance to beta-lactam and quinolone antimicrobials in non-typhoidal Salmonella isolates from humans and animals in central Ethiopia

Abstract Background Beta-lactam and quinolone antimicrobials are commonly used for treatment of infections caused by non-typhoidal Salmonella (NTS) and other pathogens. Resistance to these classes of antimicrobials has increased significantly in the recent years. However, little is known on the genetic basis of resistance to these drugs in Salmonella isolates from Ethiopia. Methods Salmonella isolates with reduced susceptibility to beta-lactams ( n \u2009=\u200943) were tested for genes encoding for beta-lactamase enzymes, and those resistant to quinolones ( n \u2009=\u200929) for mutations in the quinolone resistance determining region (QRDR) as well as plasmid mediated quinolone resistance (PMQR) genes using PCR and sequencing. Results Beta-lactamase genes ( bla ) were detected in 34 (79.1%) of the isolates. The dominant bla gene was bla TEM, recovered from 33 (76.7%) of the isolates, majority being TEM-1 (24, 72.7%) followed by TEM-57, (10, 30.3%). The bla OXA-10 and bla CTX-M-15 were detected only in a single S. Concord human isolate. Double substitutions in gyr A (Ser83-Phe\u2009+\u2009Asp87-Gly) as well as par C (Thr57-Ser\u2009+\u2009Ser80-Ile) subunits of the quinolone resistance determining region (QRDR) were detected in all S. Kentucky isolates with high level resistance to both nalidixic acid and ciprofloxacin. Single amino acid substitutions, Ser83-Phe ( n \u2009=\u20094) and Ser83-Tyr ( n \u2009=\u20091) were also detected in\ua0the gyr A gene. An isolate of S . Miami susceptible to nalidixic acid but intermediately resistant to ciprofloxacin had Thr57-Ser and an additional novel mutation (Tyr83-Phe) in the par C gene. Plasmid mediated quinolone resistance (PMQR) genes investigated were not detected in any of the isolates. In some isolates with decreased susceptibility to ciprofloxacin and/or nalidixic acid, no mutations in QRDR or PMQR genes were detected. Over half of the quinolone resistant isolates in the current study 17 (58.6%) were also resistant to at least one of the beta-lactam antimicrobials. Conclusion Acquisition of bla TEM was the principal beta-lactamase resistance mechanism and mutations within QRDR of gyr A and par C were the primary mechanism for resistance to quinolones. Further study on extended ..

Wildfire Effects on the Ecohydrology of a Sierra Nevada Watershed

The mountain watersheds of the Sierra Nevada supply the majority of California's water, but this supply has always been highly variable. The 2012-2016 drought in California has demonstrated that this water supply is also highly vulnerable to increasing temperatures and/or reduced precipitation. Not only did the 2012-2016 drought reduce water supply for human use, but it also led to unprecedented forest mortality and fire damage. Unfortunately, the fire suppression strategy that was nearly uniformly applied to mountain forests during the 20$^{th}$ century may have exacerbated the effects of drought by increasing vegetation density and thus increasing evapotranspiration and precipitation interception. Could restoring fire regimes to their pre-European settlement condition increase water yield from these forested catchments? Such a policy would also have the potential to restore the ecological function of landscapes and reduce the risk of catastrophic fires (such as the 2013 Rim Fire) by reducing fuel loads. This dissertation studies the hydrological and landscape-level ecological effects of restoring a frequent, mixed severity fire regime to the Illilouette Creek Basin in Yosemite National Park. A combination of field measurements, historical data analysis, remote sensing, and modeling approaches are employed to strengthen the argument by providing multiple lines of evidence. There is limited data available for Illilouette Creek Basin during much of the four decades in which the new fire regime became established, inhibiting direct evaluation of the fire regime's effects. Nevertheless, a variety of different metrics and analyses indicate a number of important changes that can be attributed to the restored fire regime: increased landscape diversity (including reduced forest cover), increased soil moisture and streamflow (both according to measurements and hydrological modeling), and decreased drought stress (both according to observations and from hydrological modeling)

Wildfire Effects on the Ecohydrology of a Sierra Nevada Watershed

The mountain watersheds of the Sierra Nevada supply the majority of California's water, but this supply has always been highly variable. The 2012-2016 drought in California has demonstrated that this water supply is also highly vulnerable to increasing temperatures and/or reduced precipitation. Not only did the 2012-2016 drought reduce water supply for human use, but it also led to unprecedented forest mortality and fire damage. Unfortunately, the fire suppression strategy that was nearly uniformly applied to mountain forests during the 20$^{th}$ century may have exacerbated the effects of drought by increasing vegetation density and thus increasing evapotranspiration and precipitation interception. Could restoring fire regimes to their pre-European settlement condition increase water yield from these forested catchments? Such a policy would also have the potential to restore the ecological function of landscapes and reduce the risk of catastrophic fires (such as the 2013 Rim Fire) by reducing fuel loads. This dissertation studies the hydrological and landscape-level ecological effects of restoring a frequent, mixed severity fire regime to the Illilouette Creek Basin in Yosemite National Park. A combination of field measurements, historical data analysis, remote sensing, and modeling approaches are employed to strengthen the argument by providing multiple lines of evidence. There is limited data available for Illilouette Creek Basin during much of the four decades in which the new fire regime became established, inhibiting direct evaluation of the fire regime's effects. Nevertheless, a variety of different metrics and analyses indicate a number of important changes that can be attributed to the restored fire regime: increased landscape diversity (including reduced forest cover), increased soil moisture and streamflow (both according to measurements and hydrological modeling), and decreased drought stress (both according to observations and from hydrological modeling)

Hématome rétroplacentaire (facteurs de risque, prise en charge et pronostic materno-foetal. Etude de cohorte sur dix ans)

STRASBOURG-Medecine (674822101) / SudocSudocFranceF

Post-Project Evaluation of Channel Morphology, Invasive Plant Species, and Native Fish Habitat in Putah Creek in Winters, CA Six Years After Channel Relocation

AbstractPutah Creek (drainage area = 2,000 km2) drains the slopes of Cobb Mountain in Lake County, flowing 137 km southeastward into the Yolo Bypass near Davis, California. Lower Putah Creek, the 37km reach from the Solano Diversion Dam to the Yolo Bypass, is confined within a flood control channel.  Dry Creek (drainage area = 44km2) joins Putah Creek near Winters, California.  Putah Creek is regulated by water releases from Monticello Dam at Lake Berryessa.  Dry Creek flows only part of the year and has no dams. Southward channel migration of Putah Creek from the 1990’s was threatening Putah Creek Rd., a paved county road following the south bank of the evaluated stream-section.  The new location of the Putah Creek channel also reduced the amount of gravels entering Putah Creek from Dry Creek.  This was significant because dams reduced the amount of course sediment available from upstream, leaving Dry Creek as one of the only natural sources of the gravels important to the ecology of Putah Creek. In 2005, the Lower Putah Creek Coordinating Committee implemented a project to move the channel of Putah Creek northward to its approximate historical course.  The project included the removal of invasive giant reed (Arundo donax), in part because Arundo appeared to have contributed to the unwanted channel avulsion.  We evaluated the project performance towards the goals of 1. protecting Putah Creek Road, 2. keeping invasive plant species out of the area, 3. facilitating natural transport of Dry Creek gravels into Putah Creek, and 4. improving salmonid habitat.  Our evaluation found that 1. Putah Creek has stayed within the general path of the design channel and is not returning to the southern pre-1997 channel which threatened the road, 2. there is a mix of native plant species (e.g. willow, cottonwood) and invasives (e.g. Arundo, blackberry) in the floodplain, 3. There is no physical barrier separating Putah and Dry Creek, 4.  the channel and floodplain provide good habitat complexity for native fish, but fine sediments cover most of the potential spawning gravels