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Biological Sciences Faculty Publications

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Articles 871 - 900 of 1156

Full-Text Articles in Biology

Rapid Evolution Of An Invasive Plant, John L. Maron, Montserrat Vilà, Riccardo Bommarco, Sarah Elmendorf, Paul Beardsley May 2004

Rapid Evolution Of An Invasive Plant, John L. Maron, Montserrat Vilà, Riccardo Bommarco, Sarah Elmendorf, Paul Beardsley

Biological Sciences Faculty Publications

Exotic plants often face different conditions from those experienced where they are native. The general issue of how exotics respond to unfamiliar environments within their new range is not well understood. Phenotypic plasticity has historically been seen as the primary mechanism enabling exotics to colonize large, environmentally diverse areas. However, new work indicates that exotics can evolve quickly, suggesting that contemporary evolution may be more important in invasion ecology than previously appreciated. To determine the influence of contemporary evolution, phenotypic plasticity, and founder effects in affecting phenotypic variation among introduced plants, we compared the size, fecundity, and leaf area of …

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Role Of Hydrophobic Residues In The Central Ectodomain Of Gp41 In Maintaining The Association Between Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Subunits Gp120 And Gp41, Joanne York, Jack H. Nunberg May 2004

Role Of Hydrophobic Residues In The Central Ectodomain Of Gp41 In Maintaining The Association Between Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Subunits Gp120 And Gp41, Joanne York, Jack H. Nunberg

Biological Sciences Faculty Publications

The interaction between the gp120 and gp41 subunits of the human immunodeficiency virus envelope glycoprotein serves to stabilize the virion form of the complex and to transmit receptor-induced conformational changes in gp120 to trigger the membrane fusion activity of gp41. In this study, we used site-directed mutagenesis to identify amino acid residues in the central ectodomain of gp41 that contribute to the stability of the gp120-gp41 association. We identified alanine mutations at six positions, including four tryptophan residues, which result in mutant envelope glycoprotein complexes that fail to retain gp120 on the cell surface. These envelope glycoproteins readily shed their …

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Seasonal Dynamics Of Shallow-Hyporheic-Zone Microbial Community Structure Along A Heavy-Metal Contamination Gradient, Kevin P. Feris, Philip W. Ramsey, Chris Frazar, Matthias Rillig, Johnnie N. Moore, William E. Holben Apr 2004

Seasonal Dynamics Of Shallow-Hyporheic-Zone Microbial Community Structure Along A Heavy-Metal Contamination Gradient, Kevin P. Feris, Philip W. Ramsey, Chris Frazar, Matthias Rillig, Johnnie N. Moore, William E. Holben

Biological Sciences Faculty Publications

Heavy metals contaminate numerous freshwater streams and rivers worldwide. Previous work by this group demonstrated a relationship between the structure of hyporheic microbial communities and the fluvial deposition of heavy metals along a contamination gradient during the fall season. Seasonal variation has been documented in microbial communities in numerous terrestrial and aquatic environments, including the hyporheic zone. The current study was designed to assess whether relationships between hyporheic microbial community structure and heavy-metal contamination vary seasonally by monitoring community structure along a heavy-metal contamination gradient for more than a year. No relationship between total bacterial abundance and heavy metals was …

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Gc Fractionation Enhances Microbial Community Diversity Assessment And Detection Of Minority Populations Of Bacteria By Denaturing Gradient Gel Electrophoresis, William Holben, Keving P. Feris, Anu Kettunen, Juha H. A. Apajalahti Apr 2004

Gc Fractionation Enhances Microbial Community Diversity Assessment And Detection Of Minority Populations Of Bacteria By Denaturing Gradient Gel Electrophoresis, William Holben, Keving P. Feris, Anu Kettunen, Juha H. A. Apajalahti

Biological Sciences Faculty Publications

Effectively and accurately assessing total microbial community diversity is one of the primary challenges in modern microbial ecology. This is particularly true with regard to the detection and characterization of unculturable populations and those present only in low abundance. We report a novel strategy, GC fractionation combined with denaturing gradient gel electrophoresis (GC-DGGE), which combines mechanistically different community analysis approaches to enhance assessment of microbial community diversity and detection of minority populations of microbes. This approach employs GC fractionation as an initial step to reduce the complexity of the community in each fraction. This reduced complexity facilitates subsequent detection of …

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Soil Fungi Alter Interactions Between The Invader Centaurea Maculosa And North American Natives, Ragan M. Callaway, Giles C. Thelen, Sara Barth, Philip W. Ramsey, James E. Gannon Apr 2004

Soil Fungi Alter Interactions Between The Invader Centaurea Maculosa And North American Natives, Ragan M. Callaway, Giles C. Thelen, Sara Barth, Philip W. Ramsey, James E. Gannon

Biological Sciences Faculty Publications

Soil microbes may affect the way exotic invasive plants interact with native neighbors. We investigated the effects of soil fungi on interactions between the invasive weed Centaurea maculosa (spotted knapweed) and six species native to the intermountain prairies of the northwestern United States. We also compared the effect of C. maculosa on the composition of the soil microbial community to that of the native species. In the field, fungicide (Benomyl) reduced AM mycorrhizal colonization of C. maculosa roots by >80%. Fungicide did not significantly reduce non-AM fungi. When grown alone, the biomass of C. maculosa was not affected by the …

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Variation In Sulfide Tolerance Of Photosystem Ii In Phylogenetically Diverse Cyanobacteria From Sulfidic Habitats, Scott R. Miller, Brad M. Bebout Feb 2004

Variation In Sulfide Tolerance Of Photosystem Ii In Phylogenetically Diverse Cyanobacteria From Sulfidic Habitats, Scott R. Miller, Brad M. Bebout

Biological Sciences Faculty Publications

Physiological and molecular phylogenetic approaches were used to investigate variation among 12 cyanobacterial strains in their tolerance of sulfide, an inhibitor of oxygenic photosynthesis. Cyanobacteria from sulfidic habitats were found to be phylogenetically diverse and exhibited an approximately 50-fold variation in photosystem II performance in the presence of sulfide. Whereas the degree of tolerance was positively correlated with sulfide levels in the environment, a strain's phenotype could not be predicted from the tolerance of its closest relatives. These observations suggest that sulfide tolerance is a dynamic trait primarily shaped by environmental variation. Despite differences in absolute tolerance, similarities among strains …

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Splicing Affects Presentation Of Rna Dimerization Signals In Hiv-2 In Vitro, Jean-Marc Lanchy, Quenna N. Szafran, J. Stephen Lodmell Jan 2004

Splicing Affects Presentation Of Rna Dimerization Signals In Hiv-2 In Vitro, Jean-Marc Lanchy, Quenna N. Szafran, J. Stephen Lodmell

Biological Sciences Faculty Publications

During retroviral replication, full-length viral RNAs are encapsidated into new virus particles, while spliced RNAs are excluded. The Retroviridae are unique among viruses in that infectious viral particles contain a dimer of two identical genomic RNA strands. A variety of experimental data has suggested that dimerization and encapsidation of full-length viral RNAs are linked processes, although whether dimerization is a prerequisite for encapsidation, or conversely, dimerization follows encapsidation, has not been firmly established. If dimerization was the sole determinant for encapsidation, then spliced viral RNAs might be expected to display a reduced capacity for dimerization, resulting in their exclusion from …

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Chemical Defenses In Garlic Mustard (Alliaria Petiolata) And Their Potential Role In Species Interactions In Forest Understories, Don Cipollini Jan 2004

Chemical Defenses In Garlic Mustard (Alliaria Petiolata) And Their Potential Role In Species Interactions In Forest Understories, Don Cipollini

Biological Sciences Faculty Publications

Garlic mustard [Alliaria petiolata [(M. Bieb) Cavara & Grande; Brassicaceae] is a European native biennial herb, first recorded on Long Island, NY in the 1860s, and is expanding rapidly in northeastern and midwestern forests in the U.S. and in southern Canada. Garlic mustard flourishes in moist woodlands with moderate exposure to light, but it can grow in a diversity of other habitats. It is found in natural areas, woodlots, and along edges of agricultural fields and lawns throughout North America. Several life history traits likely contribute to the invasiveness of this species. It has a high inbreeding rate and can …

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On The Ecological Status Of The Concept "Boundary Conditions" - A Few Methodological Remarks, Lubomira Burchardt, Krzystof Lastowski, Harold G. Marshall Jan 2004

On The Ecological Status Of The Concept "Boundary Conditions" - A Few Methodological Remarks, Lubomira Burchardt, Krzystof Lastowski, Harold G. Marshall

Biological Sciences Faculty Publications

Plant and animal populations are frequently found in habitats where the environmental conditions are considered extreme or challenging for life form to exist. These conditions may be classified as either: (1) Supreme: a situation characteristic of degradation conditions where only a few species live under stress, and (2) Extra-ordinary: habitats that provide high biodiversity that are under stress conditions. Due to the differences in what we consider extreme conditions, it is necessary to distinguish between these two categories, because they are not comparable. Our presentation will include examples of these two extreme environmental categories.

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Thermodynamic Characterization Of The Binding Of Activator Of G Protein Signaling 3 (Ags3) And Peptides Derived From Ags3 With G Alpha I1, Anirban Adhikari, Stephen R. Sprang Dec 2003

Thermodynamic Characterization Of The Binding Of Activator Of G Protein Signaling 3 (Ags3) And Peptides Derived From Ags3 With G Alpha I1, Anirban Adhikari, Stephen R. Sprang

Biological Sciences Faculty Publications

Activator of G protein signaling 3 (AGS3) is a guanine nucleotide dissociation inhibitor (GDI) that contains four G protein regulatory (GPR) or GoLoco motifs in its C-terminal domain. The entire C-terminal domain (AGS3-C) as well as certain peptides corresponding to individual GPR motifs of AGS3 bound to G alpha i1 and inhibited the binding of GTP by stabilizing the GDP-bound conformation of G alpha i1. The stoichiometry, free energy, enthalpy, and dissociation constant for binding of AGS3-C to G alpha i1 were determined using isothermal titration calorimetry. AGS3-C possesses two apparent high affinity (Kd approximately 20 nm) and two apparent …

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Mitogenic Effect Of Bartonella Bacilliformis On Human Vascular Endothelial Cells And Involvement Of Groel, Michael F. Minnick, Laura S. Smitherman, D. Scott Samuels Dec 2003

Mitogenic Effect Of Bartonella Bacilliformis On Human Vascular Endothelial Cells And Involvement Of Groel, Michael F. Minnick, Laura S. Smitherman, D. Scott Samuels

Biological Sciences Faculty Publications

Bartonellae are bacterial pathogens for a wide variety of mammals. In humans, bartonellosis can result in angioproliferative lesions that are potentially life threatening to the patient, including bacillary angiomatosis, bacillary peliosis, and verruga peruana. The results of this study show that Bartonella bacilliformis, the agent of Oroya fever and verruga peruana, produces a proteinaceous mitogen for human vascular endothelial cells (HUVECs) that acts in a dose-dependent fashion in vitro with maximal activity at >72 h of exposure and results in a 6- to 20-fold increase in cell numbers relative to controls. The mitogen increases bromodeoxyuridine (BrdU) incorporation into HUVECs …

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Aada Confers Streptomycin Resistance In Borrelia Burgdorferi, Kristi L. Frank, Sharyl F. Bundle, Michele E. Kresge, Christian H. Eggers, D. Scott Samuels Nov 2003

Aada Confers Streptomycin Resistance In Borrelia Burgdorferi, Kristi L. Frank, Sharyl F. Bundle, Michele E. Kresge, Christian H. Eggers, D. Scott Samuels

Biological Sciences Faculty Publications

To enhance genetic manipulation of the Lyme disease spirochete Borrelia burgdorferi, we assayed the aadA gene for the ability to confer resistance to the antibiotics spectinomycin and streptomycin. Using the previously described pBSV2 as a backbone, a shuttle vector, termed pKFSS1, which carries the aadA open reading frame fused to the B. burgdorferi flgB promoter was constructed. The hybrid flgB promoter-aadA cassette confers resistance to spectinomycin and streptomycin in both B. burgdorferi and Escherichia coli. pKFSS1 has a replication origin derived from the 9-kb circular plasmid and can be comaintained in B. burgdorferi with extant shuttle vector pCE320, which has …

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Evolution Of Avian Locomotion: Correlates Of Flight Style, Locomotor Modules, Nesting Biology, Body Size, Development, And The Origin Of Flapping Flight, Kenneth P. Dial Oct 2003

Evolution Of Avian Locomotion: Correlates Of Flight Style, Locomotor Modules, Nesting Biology, Body Size, Development, And The Origin Of Flapping Flight, Kenneth P. Dial

Biological Sciences Faculty Publications

No abstract provided.

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Differences In Hyporheic-Zone Microbial Community Structure Along A Heavy-Metal Contamination Gradient, Kevin P. Feris, Philip W. Ramsey, Frazar Chris, Johnnie N. Moore, James E. Gannon, William E. Holben Sep 2003

Differences In Hyporheic-Zone Microbial Community Structure Along A Heavy-Metal Contamination Gradient, Kevin P. Feris, Philip W. Ramsey, Frazar Chris, Johnnie N. Moore, James E. Gannon, William E. Holben

Biological Sciences Faculty Publications

Heavy metals contaminate numerous freshwater streams and rivers worldwide. Previous work by this group demonstrated a relationship between the structure of hyporheic microbial communities and the fluvial deposition of heavy metals along a contamination gradient during the fall season. Seasonal variation has been documented in microbial communities in numerous terrestrial and aquatic environments, including the hyporheic zone. The current study was designed to assess whether relationships between hyporheic microbial community structure and heavy-metal contamination vary seasonally by monitoring community structure along a heavy-metal contamination gradient for more than a year. No relationship between total bacterial abundance and heavy metals was …

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Selective Plating Underestimates Abundance And Shows Differential Recovery Of Bifidobacterial Species From Human Feces, Juha H. A. Apajalahti, Anu Kettunen, Päivi H. Nurminen, Hanna Jatila, William E. Holben Sep 2003

Selective Plating Underestimates Abundance And Shows Differential Recovery Of Bifidobacterial Species From Human Feces, Juha H. A. Apajalahti, Anu Kettunen, Päivi H. Nurminen, Hanna Jatila, William E. Holben

Biological Sciences Faculty Publications

The aim of the present work was to compare the efficacies and levels of selectivity of different culture-dependent and -independent methods for analyzing bifidobacteria in human stool samples. The three different culture media used here significantly differed from each other, particularly with regard to the recovery of Bifidobacterium adolescentis. Bifidobacterium medium failed to recover B. adolescentis; Beerens medium recovered some B. adolescentis organisms (17% of total bifidobacteria), whereas tomato-Eugon medium recovered mainly B. adolescentis organisms (58% of total bifidobacteria). A culture-independent method that combines GC fractionation of bacterial community DNA and 16S rRNA sequencing indicated that B. adolescentis organisms accounted …

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Monitoring Immediate-Early Gene Expression Through Firefly Luciferase Imaging Of Hrs/J Hairless Mice, Michael E. Geusz, Anne M. Collaco Aug 2003

Monitoring Immediate-Early Gene Expression Through Firefly Luciferase Imaging Of Hrs/J Hairless Mice, Michael E. Geusz, Anne M. Collaco

Biological Sciences Faculty Publications

Background: Gene promoters fused to the firefly luciferase gene (luc) are useful for examining gene regulation in live transgenic mice and they provide unique views of functioning organs. The dynamics of gene expression in cells and tissues expressing luciferase can be observed by imaging this enzyme's bioluminescent oxidation of luciferin. Neural pathways involved in specific behaviors have been identified by localizing expression of immediate-early genes such as c-fos. A transgenic mouse line with luc controlled by the human c-fos promoter (fos::luc) has enabled gene expression imaging in brain slice cultures. To optimize imaging of immediate-early gene expression throughout intact mice, …

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A Structural Linkage Between The Dimerization And Encapsidation Signals In Hiv-2 Leader Rna, J. M. Lanchy, J. D. Ivanovitch, J. Stephen Lodmell Aug 2003

A Structural Linkage Between The Dimerization And Encapsidation Signals In Hiv-2 Leader Rna, J. M. Lanchy, J. D. Ivanovitch, J. Stephen Lodmell

Biological Sciences Faculty Publications

The 5' untranslated leader region of retroviral RNAs contains noncoding information that is essential for viral replication, including signals for transcriptional transactivation, splicing, primer binding for reverse transcription, dimerization of the genomic RNA, and encapsidation of the viral RNA into virions. These RNA motifs have considerable structural and functional overlap. in this study, we investigate the conformational dynamics associated with the use and silencing of a sequence in HIV-2 RNA that is involved in genomic RNA dimerization called stem-loop 1 (SL1) and its relationship with a flanking sequence that is known to be important for encapsidation of viral RNAs. We …

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Ribosomal Localization Of Translation Initiation Factor If2, Stefano Marzi, William Knight, Letizia Brandi, Enrico Caserta, Natalia Soboleva, Walter E. Hill, Claudio O. Gualerzi, J. Stephen Lodmell Aug 2003

Ribosomal Localization Of Translation Initiation Factor If2, Stefano Marzi, William Knight, Letizia Brandi, Enrico Caserta, Natalia Soboleva, Walter E. Hill, Claudio O. Gualerzi, J. Stephen Lodmell

Biological Sciences Faculty Publications

Bacterial translation initiation factor IF2 is a GTP-binding protein that catalyzes binding of initiator fMet-tRNA in the ribosomal P site. The topographical localization of IF2 on the ribosomal subunits, a prerequisite for understanding the mechanism of initiation complex formation, has remained elusive. Here, we present a model for the positioning of IF2 in the 70S initiation complex as determined by cleavage of rRNA by the chemical nucleases Cu(II):1,10-orthophenanthroline and Fe(II):EDTA tethered to cysteine residues introduced into IF2. Two specific amino acids in the GII domain of IF2 are in proximity to helices H3, H4, H17, and H18 of 16S rRNA. …

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River Flows And Water Wars: Emerging Science For Environmental Decision Making, N. Leroy Poff, J. David Allan, Margaret A. Palmer, David D. Hart, Brian D. Richter, Angela H. Arthington, Kevin H. Rogers, Judy L. Meyer, Jack Arthur Stanford Aug 2003

River Flows And Water Wars: Emerging Science For Environmental Decision Making, N. Leroy Poff, J. David Allan, Margaret A. Palmer, David D. Hart, Brian D. Richter, Angela H. Arthington, Kevin H. Rogers, Judy L. Meyer, Jack Arthur Stanford

Biological Sciences Faculty Publications

Real and apparent conflicts between ecosystem and human needs for fresh water are contributing to the emergence of an alternative model for conducting river science around the world. The core of this new paradigm emphasizes the need to forge new partnerships between scientists and other stakeholders where shared ecological goals and river visions are developed, and the need for new experimental approaches to advance scientific understanding at the scales relevant to whole-river management. We identify four key elements required to make this model succeed: existing and planned water projects represent opportunities to conduct ecosystem-scale experiments through controlled river flow manipulations; …

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Effect Of Phosphorus Amendments On Present Day Plankton Communities In Pelagic Lake Erie, Steven W. Wilhelm, Jennifer M. Debruyn, Osnat Gillor, Michael R. Twiss, Kasey Livingston, Richard A. Bourbonniere, Lisa D. Pickell, Charles G. Trick, Amanda L. Dean, Robert Michael Mckay Jul 2003

Effect Of Phosphorus Amendments On Present Day Plankton Communities In Pelagic Lake Erie, Steven W. Wilhelm, Jennifer M. Debruyn, Osnat Gillor, Michael R. Twiss, Kasey Livingston, Richard A. Bourbonniere, Lisa D. Pickell, Charles G. Trick, Amanda L. Dean, Robert Michael Mckay

Biological Sciences Faculty Publications

To address questions regarding the potential impact of elevated total phosphorus (TP) inputs (due to relaxed regulations of TP loading), a series of TP enrichment experiments were conducted at pelagic stations in the 3 hydrologically distinct basins of Lake Erie. Results of nutrient assimilation measurements and assays for nutrient bioavailability suggest that the chemical speciation, and not concentration, of nitrogenous compounds may influence phytoplankton community structure; this in turn may lead to the selective proliferation of cyanobacteria in the eastern basin of the lake. Assays with cyanobacterial bioluminescent reporter systems for P and N availability as well as N-tot:P-tot assimilation …

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Differences In Cottonwood Growth Between A Losing And A Gaining Reach Of An Alluvial Floodplain, Mary J. Harner, Jack Arthur Stanford Jun 2003

Differences In Cottonwood Growth Between A Losing And A Gaining Reach Of An Alluvial Floodplain, Mary J. Harner, Jack Arthur Stanford

Biological Sciences Faculty Publications

Interstitial flow of river (hyporheic) water influences algal productivity, benthic assemblages, and locations of fish spawning. However, little is known of the effects of hyporheic flow on the growth of riparian vegetation. By increasing water availability and nutrient delivery, regional upwelling of hyporheic water may increase the growth of terrestrial vegetation. We tested and accepted the hypothesis that cottonwood trees (Populus trichocarpa) in a gaining reach of an alluvial floodplain grow faster than trees in a losing reach by comparing basal areas and ages on an expansive floodplain in western Montana (USA). Trees in the gaining reach had …

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Phenotypic Plasticity And Interactions Among Plants, Ragan M. Callaway, Steven C. Pennings, Christina L. Richards May 2003

Phenotypic Plasticity And Interactions Among Plants, Ragan M. Callaway, Steven C. Pennings, Christina L. Richards

Biological Sciences Faculty Publications

We know a great deal about the plastic responses of plant phenotypes to the abiotic and biotic environment, but very little about the consequences of phenotypic plasticity for plant communities. In other words, we know that plant traits can vary widely for a given genotype, but we know little about the importance of trait-mediated interactions (TMI) among plants. Here, we discuss three major factors that affect the expression of phenotypic plasticity: variation in the abiotic environment, variation in the presence or identity of neighbors, and variation in herbivory. We consider how plastic responses to these factors might affect interactions among …

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Differential Expression Of The Invasion-Associated Locus B (Ialb) Gene Of Bartonella Bacilliformis In Response To Environmental Cues, Sherry A. Coleman, Michael F. Minnick Apr 2003

Differential Expression Of The Invasion-Associated Locus B (Ialb) Gene Of Bartonella Bacilliformis In Response To Environmental Cues, Sherry A. Coleman, Michael F. Minnick

Biological Sciences Faculty Publications

Bartonella bacilliformis is the causative agent of the biphasic human disease, Oroya fever. During the primary disease phase, up to 100% of the circulating erythrocytes can be parasitized and 80% lysed. During the secondary phase of this disease, bacterial invasion shifts to endothelial cells lining the vasculature. B. bacilliformis is transferred between human hosts by the sandfly, Lutzomyia verrucarum. To investigate the regulation of ialB by environmental cues signaling vector-to-host transmission; nuclease protection assays were performed to compare the amount of ialB mRNA in bacteria subjected to temperature shift, pH change, oxidative stress, or hemin limitation. The amount of ialB …

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Mapping The Galpha13 Binding Interface Of The Rgrgs Domain Of P115rhogef, Zhe Chen, William D. Singer, Clark D. Wells, Stephen R. Sprang, Paul C. Sternweis Mar 2003

Mapping The Galpha13 Binding Interface Of The Rgrgs Domain Of P115rhogef, Zhe Chen, William D. Singer, Clark D. Wells, Stephen R. Sprang, Paul C. Sternweis

Biological Sciences Faculty Publications

Structural requirements for function of the Rho GEF (guanine nucleotide exchange factor) regulator of G protein signaling (rgRGS) domains of p115RhoGEF and homologous exchange factors differ from those of the classical RGS domains. An extensive mutagenesis analysis of the p115RhoGEF rgRGS domain was undertaken to determine its functional interface with the Galpha(13) subunit. Results indicate that there is global resemblance between the interaction surface of the rgRGS domain with Galpha(13) and the interactions of RGS4 and RGS9 with their Galpha substrates. However, there are distinct differences in the distribution of functionally critical residues between these structurally similar surfaces and an …

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Energetic Adaptations Along A Broad Latitudinal Gradient: Implications For Widely Distributed Assemblages, Jeffrey Gibson Miner, James E. Garvey, Dennis R. Devries, Russell A. Wright Feb 2003

Energetic Adaptations Along A Broad Latitudinal Gradient: Implications For Widely Distributed Assemblages, Jeffrey Gibson Miner, James E. Garvey, Dennis R. Devries, Russell A. Wright

Biological Sciences Faculty Publications

Most community-based models in ecology assume that all individuals within a species respond similarly to environmental conditions and thereby exert identical effects as consumers or prey. Rather, individuals differ among systems, with important implications for population demographics and community interactions. For widely distributed assemblages made up of poikilotherms with high first-year mortality, species-specific differences in growth reaction norms as affected by both temperature and genotype will influence biotic interactions. For a broadly distributed fish assemblage, first-year growth does not vary with latitude for a planktivorous prey species, but declines with increasing latitude for a terminal piscivore. Size-based competitive interactions between …

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Five-Member Gene Family Of Bartonella Quintana, Michael F. Minnick, Kate N. Sappington, Laura S. Smitherman, Siv G. E. Andersson, Olof Karlberg, James A. Carroll Feb 2003

Five-Member Gene Family Of Bartonella Quintana, Michael F. Minnick, Kate N. Sappington, Laura S. Smitherman, Siv G. E. Andersson, Olof Karlberg, James A. Carroll

Biological Sciences Faculty Publications

Bartonella quintana, the agent of trench fever and an etiologic agent of bacillary angiomatosis, has an extraordinarily high hemin requirement for growth compared to other bacterial pathogens. We previously identified the major hemin receptor of the pathogen as a 30-kDa surface protein, termed HbpA. This report describes four additional homologues that share approximately 48% amino acid sequence identity with hbpA. Three of the genes form a paralagous cluster, termed hbpCAB, whereas the other members, hbpD and hbpE, are unlinked. Secondary structure predictions and other evidence suggest that Hbp family members are beta-barrels located in the outer membrane and contain eight …

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Wing-Assisted Incline Running And The Evolution Of Flight, Kenneth P. Dial Jan 2003

Wing-Assisted Incline Running And The Evolution Of Flight, Kenneth P. Dial

Biological Sciences Faculty Publications

Flapping wings of galliform birds are routinely used to produce aerodynamic forces oriented toward the substrate to enhance hindlimb traction. Here, I document this behavior in natural and laboratory settings. Adult birds fully capable of aerial flight preferentially employ wing-assisted incline running (WAIR), rather than flying, to reach elevated refuges (such as cliffs, trees, and boulders). From the day of hatching and before attaining sustained aerial flight, developing ground birds use WAIR to enhance their locomotor performance through improved foot traction, ultimately permitting vertical running. WAIR provides insight from behaviors observable in living birds into the possible role of incipient …

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Gyra Mutations In Ciprofloxacin-Resistant Bartonella Bacilliformis Strains Obtained In Vitro, Michael F. Minnick, Zachary R. Wilson, Laura S. Smitherman, D. Scott Samuels Jan 2003

Gyra Mutations In Ciprofloxacin-Resistant Bartonella Bacilliformis Strains Obtained In Vitro, Michael F. Minnick, Zachary R. Wilson, Laura S. Smitherman, D. Scott Samuels

Biological Sciences Faculty Publications

We isolated and characterized mutants of Bartonella bacilliformis that are resistant to the fluoroquinolone antibiotic ciprofloxacin, which targets the A subunit of DNA gyrase. Mutants had single point mutations in the gyrA gene that changed either Asp-90 to Gly or Asp-95 to Asn and had 3- or 16-fold higher resistance, respectively, to ciprofloxacin than did wild-type B. bacilliformis. Asp-95 is homologous to Asp-87 of Escherichia coli GyrA and is a common residue mutated in fluoroquinolone-resistant strains of other bacteria. This is the first report of a mutation at an Asp-90 homologue, which corresponds to Asp-82 in E. coli GyrA.

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Soil Fungi And The Effects Of An Invasive Forb On Grasses: Neighbor Identity Matters, Ragan M. Callaway, Bruce E. Mahall, Chris Wicks, Joel Pankey, Catherine Zabinski Jan 2003

Soil Fungi And The Effects Of An Invasive Forb On Grasses: Neighbor Identity Matters, Ragan M. Callaway, Bruce E. Mahall, Chris Wicks, Joel Pankey, Catherine Zabinski

Biological Sciences Faculty Publications

We studied the effects of soil fungi on interactions between Centaurea melitensis, an exotic invasive weed in central California, and two co-occurring grasses, Nassella pulchra and Avena barbata. The fungicide benomyl reduced the abundance of arbuscular mycorrhizal (AM) fungi in plant roots but did not affect non-AM fungi. Centaurea plants grown alone were >50% smaller with the resident microbial community intact than when benomyl was applied. When grown with Nassella, the effect of benomyl was reversed. Centaurea grew almost five times larger with the resident microbial community intact. Fungicide had no effect on the biomass of Centaurea …

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Increase In Biomass And Soldier Production For Coptotermes Formosanus (Shiraki) Workers Maintained In The Laboratory For Up To Nine Months, Deborah Waller Jan 2003

Increase In Biomass And Soldier Production For Coptotermes Formosanus (Shiraki) Workers Maintained In The Laboratory For Up To Nine Months, Deborah Waller

Biological Sciences Faculty Publications

The factors that influence rates of soldier production in subterranean termites are poorly understood. In the present study, foraging groups of Coptotermes formosanus Shiraki were collected from baldcypress trees in Lake Charles, Lousiana, in November 1985, and February, April/May and August 1986. Termites were maintained in the laboratory for nine months, seven months, four/five months and zero months, respectively, and then examined for survivorship, termite biomass and soldier production after incubation for an additional five weeks at 30° C. Within collection periods, there was no association between survivorship and soldier production or between mean dry biomass and soldier production. However, …

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