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Articles 421 - 450 of 602

Full-Text Articles in Biology

Cost Of Defense In The Context Of Plant Competition: Brassica Rapa May Grow And Defend, David H. Siemens, Shannon H. Garner, Thomas Mitchell-Olds, Ragan M. Callaway Feb 2002

Cost Of Defense In The Context Of Plant Competition: Brassica Rapa May Grow And Defend, David H. Siemens, Shannon H. Garner, Thomas Mitchell-Olds, Ragan M. Callaway

Biological Sciences Faculty Publications

Theory on costs of plant defense against herbivory in stressful environments predicts that costs should increase when competition is intense. This amplifies a fundamental dilemma that plants are thought to face: allocate limited resources to grow fast enough to compete, or invest these resources in secondary metabolites to maintain defense. We studied costs associated with genetic and environmental variation in secondary metabolite production of Brassica rapa in the presence and absence of the generalist competitor Lolium perenne. We used experimental quantitative genetics (artificial selection) to manipulate genetic variation, and herbivore-induction treatments to produce environmental variation in myrosinase and glucosinolate …

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Crystallization Of Complex Between Soluble Domains Of Adenylyl Cyclase And Activated Gs Alpha, John J. Tesmer, Roger K. Sunahara, David A. Fancy, Alfred G. Gilman, Stephen R. Sprang Jan 2002

Crystallization Of Complex Between Soluble Domains Of Adenylyl Cyclase And Activated Gs Alpha, John J. Tesmer, Roger K. Sunahara, David A. Fancy, Alfred G. Gilman, Stephen R. Sprang

Biological Sciences Faculty Publications

No abstract provided.

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Percent G+C Profiling Accurately Reveals Diet-Related Differences In The Gastrointestinal Microbial Community Of Broiler Chickens, Juha H. A. Apajalahti, Anu Kettunen, Michael R. Bedford, William E. Holben Dec 2001

Percent G+C Profiling Accurately Reveals Diet-Related Differences In The Gastrointestinal Microbial Community Of Broiler Chickens, Juha H. A. Apajalahti, Anu Kettunen, Michael R. Bedford, William E. Holben

Biological Sciences Faculty Publications

Broiler chickens from eight commercial farms in Southern Finland were analyzed for the structure of their gastrointestinal microbial community by a nonselective DNA-based method, percent G+C-based profiling. The bacteriological impact of the feed source and in-farm whole-wheat amendment of the diet was assessed by percent G+C profiling. Also, a phylogenetic 16S rRNA gene (rDNA)-based study was carried out to aid in interpretation of the percent G+C profiles. This survey showed that most of the 16S rDNA sequences found could not be assigned to any previously known bacterial genus or they represented an unknown species of one of the taxonomically heterogeneous …

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Isolation And Characterization Of A Novel As(V)-Reducing Bacterium: Implications For Arsenic Mobilization And The Genus Desulfitobacterium, Allison Niggemyer, Stefan Spring, Erko Stackebrandt, Frank Rosenzweig Dec 2001

Isolation And Characterization Of A Novel As(V)-Reducing Bacterium: Implications For Arsenic Mobilization And The Genus Desulfitobacterium, Allison Niggemyer, Stefan Spring, Erko Stackebrandt, Frank Rosenzweig

Biological Sciences Faculty Publications

Dissimilatory arsenate-reducing bacteria have been implicated in the mobilization of arsenic from arsenic-enriched sediments. An As(V)-reducing bacterium, designated strain GBFH, was isolated from arsenic-contaminated sediments of Lake Coeur d'Alene, Idaho. Strain GBFH couples the oxidation of formate to the reduction of As(V) when formate is supplied as the sole carbon source and electron donor. Additionally, strain GBFH is capable of reducing As(V), Fe(III), Se(VI), Mn(IV) and a variety of oxidized sulfur species. 16S ribosomal DNA sequence comparisons reveal that strain GBFH is closely related to Desulfitobacterium hafniense DCB-2T and Desulfitobacterium frappieri PCP-1T. Comparative physiology demonstrates that D …

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Facilitation And Competition On Gradients In Alpine Plant Communities, Philippe Choler, Richard Michalet, Ragan M. Callaway Dec 2001

Facilitation And Competition On Gradients In Alpine Plant Communities, Philippe Choler, Richard Michalet, Ragan M. Callaway

Biological Sciences Faculty Publications

We conducted a neighbor removal experiment in natural alpine plant communities of the southwestern Alps to test for the relative importance of competitive and facilitative interactions along elevational and topographical gradients. The experimental sites were chosen to encompass most of the floristic diversity observed along gradients of elevation and topography, which are the two main ecological gradients associated with alpine plant communities in the western Alps. The effects of neighbor removal on the survival, aboveground biomass, and reproduction of five target species were tested at each of six experimental sites. Using biomass data, we calculated relative competitive index (RCI) and …

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Structural And Functional Analysis Of Interhelical Interactions In The Human Immunodeficiency Virus Type 1 Gp41 Envelope Glycoprotein By Alanine-Scanning Mutagenesis, Min Lu, Marisa O. Stoller, Shilong Wang, Jie Liu, Melinda B. Fagan, Jack H. Nunberg Nov 2001

Structural And Functional Analysis Of Interhelical Interactions In The Human Immunodeficiency Virus Type 1 Gp41 Envelope Glycoprotein By Alanine-Scanning Mutagenesis, Min Lu, Marisa O. Stoller, Shilong Wang, Jie Liu, Melinda B. Fagan, Jack H. Nunberg

Biological Sciences Faculty Publications

Membrane fusion by human immunodeficiency virus type 1 (HIV-1) is promoted by the refolding of the viral envelope glycoprotein into a fusion-active conformation. The structure of the gp41 ectodomain core in its fusion-active state is a trimer of hairpins in which three antiparallel carboxyl-terminal helices pack into hydrophobic grooves on the surface of an amino-terminal trimeric coiled coil. In an effort to identify amino acid residues in these grooves that are critical for gp41 activation, we have used alanine-scanning mutagenesis to investigate the importance of individual side chains in determining the biophysical properties of the gp41 core and the membrane …

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Structure Of The Rgrgs Domain Of P115rhogef, Zhe Chen, Clark D. Wells, Paul C. Sternweis, Stephen R. Sprang Sep 2001

Structure Of The Rgrgs Domain Of P115rhogef, Zhe Chen, Clark D. Wells, Paul C. Sternweis, Stephen R. Sprang

Biological Sciences Faculty Publications

p115RhoGEF, a guanine nucleotide exchange factor for Rho GTPase, is also a GTPase activating protein (GAP) for G12 and G13 heterotrimeric Gα subunits. Near its N-terminus, p115RhoGEF contains a domain (rgRGS) with remote sequence identity to RGS (regulators of G protein signaling) domains. The rgRGS domain is necessary but not sufficient for the GAP activity of p115RhoGEF. The 1.9 Å resolution crystal structure of the rgRGS domain shows structural similarity to RGS domains but possesses a C-terminal extension that folds into a layer of helices that pack against the hydrophobic core of the domain. Mutagenesis experiments show that …

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Transduction By Phi Bb-1, A Bacteriophage Of Borrelia Burgdorferi, Christian H. Eggers, Betsy J. Kimmel, James L. Bono, Abdallah F. Elias, Patricia Rosa, D. Scott Samuels Aug 2001

Transduction By Phi Bb-1, A Bacteriophage Of Borrelia Burgdorferi, Christian H. Eggers, Betsy J. Kimmel, James L. Bono, Abdallah F. Elias, Patricia Rosa, D. Scott Samuels

Biological Sciences Faculty Publications

We previously described a bacteriophage of the Lyme disease agent Borrelia burgdorferi designated phi BB-1. This phage packages the host complement of the 32-kb circular plasmids (cp32s), a group of homologous molecules found throughout the genus Borrelia. To demonstrate the ability of phi BB-1 to package and transduce DNA, a kanamycin resistance cassette was inserted into a cloned fragment of phage DNA, and the resulting construct was transformed into B. burgdorferi CA-11.2A cells. The kan cassette recombined into a resident cp32 and was stably maintained. The cp32 containing the kan cassette was packaged by phi BB-1 released from this B. …

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Restoring Enriched Grasslands: Effects Of Mowing On Species Richness, Productivity, And Nitrogen Retention, John L. Maron, Robert L. Jefferies Aug 2001

Restoring Enriched Grasslands: Effects Of Mowing On Species Richness, Productivity, And Nitrogen Retention, John L. Maron, Robert L. Jefferies

Biological Sciences Faculty Publications

Species-rich grasslands that become enriched with nitrogen often suffer decreases in species richness, increases in plant biomass, and invasion by weedy exotic species. Suitable techniques to restore enriched grasslands and reestablish native communities are increasingly needed. Here we report results of a 5-yr experiment in enriched coastal prairie grasslands (Bodega Marine Reserve, Bodega Bay, California, USA), to determine the combined effects of mowing and biomass removal on total soil nitrogen, net rates of mineralization, nitrogen retention, and species richness and biomass. We mowed and removed plant biomass from plots in areas where the N-fixing shrub, bush lupine (Lupinus arboreus …

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Establishing A Direct Role For The Bartonella Bacilliformis Invasion-Associated Locus B (Ialb) Protein In Human Erythrocyte Parasitism, Sherry A. Coleman, Michael F. Minnick Jul 2001

Establishing A Direct Role For The Bartonella Bacilliformis Invasion-Associated Locus B (Ialb) Protein In Human Erythrocyte Parasitism, Sherry A. Coleman, Michael F. Minnick

Biological Sciences Faculty Publications

The invasion-associated locus A and B genes (ialAB) of Bartonella bacilliformis were previously shown to confer an erythrocyte-invasive phenotype upon Escherichia coli, indirectly implicating their role in virulence. We report the first direct demonstration of a role for ialB as a virulence factor in B, bacilliformis. The presence of a secretory signal sequence and amino acid sequence similarity to two known outer membrane proteins involved in virulence suggested that IalB was an outer membrane protein, To develop an antiserum for protein localization, the ialB gene was cloned in frame into an expression vector with a six-histidine tag and under control …

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C2 Domains From Different Ca2+ Signaling Pathways Display Functional And Mechanistic Diversity, E. A. Nalefski, M. A. Wisner, J. Z. Chen, S. R. Sprang, M. Fukuda, K. Mikoshiba, J. J. Falke Mar 2001

C2 Domains From Different Ca2+ Signaling Pathways Display Functional And Mechanistic Diversity, E. A. Nalefski, M. A. Wisner, J. Z. Chen, S. R. Sprang, M. Fukuda, K. Mikoshiba, J. J. Falke

Biological Sciences Faculty Publications

The ubiquitous C2 domain is a conserved Ca2+-triggered membrane-docking module that targets numerous signaling proteins to membrane surfaces where they regulate diverse processes critical for cell signaling. In this study, we quantitatively compared the equilibrium and kinetic parameters of C2 domains isolated from three functionally distinct signaling proteins: cytosolic phospholipase A2-α (cPLA2-α), protein kinase C-β (PKC-β), and synaptotagmin-IA (Syt-IA). The results show that equilibrium C2 domain docking to mixed phosphatidylcholine and phosphatidylserine membranes occurs at micromolar Ca2+ concentrations for the cPLA2-α C2 domain, but requires 3- and 10-fold higher Ca2+ …

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Experimental Model Of Human Body Louse Infection Using Green Fluorescent Protein-Expressing Bartonella Quintana, Pierre-Edouard Fournier, Michael F. Minnick, Hubert Lepidi, Eric Salvo, Didier Raoult Mar 2001

Experimental Model Of Human Body Louse Infection Using Green Fluorescent Protein-Expressing Bartonella Quintana, Pierre-Edouard Fournier, Michael F. Minnick, Hubert Lepidi, Eric Salvo, Didier Raoult

Biological Sciences Faculty Publications

A laboratory colony of human body lice was experimentally infected by feeding on rabbits made artificially bacteremic with a green fluorescent protein-expressing Bartonella quintana. B. quintana was detected in the gut and feces until death but not in the eggs. The life span of the lice was not modified. The rabbit model should provide valuable clues to the role of lice in the transmission of B. quintana.

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Antibody Binding And Neutralization Of Primary And T-Cell Line-Adapted Isolates Of Human Immunodeficiency Virus Type 1, Joanne York, Kathryn E. Follis, Meg Trahey, Phillipe N. Nyambi, Susan Zolla-Pazner, Jack H. Nunberg Mar 2001

Antibody Binding And Neutralization Of Primary And T-Cell Line-Adapted Isolates Of Human Immunodeficiency Virus Type 1, Joanne York, Kathryn E. Follis, Meg Trahey, Phillipe N. Nyambi, Susan Zolla-Pazner, Jack H. Nunberg

Biological Sciences Faculty Publications

The relative resistance of human immunodeficiency virus type 1 (HIV-1) primary isolates (PIs) to neutralization by a wide range of antibodies remains a theoretical and practical barrier to the development of an effective HIV vaccine. One model to account for the differential neutralization sensitivity between Pls and laboratory (or T-cell line-adapted [TCLA]) strains of HN suggests that the envelope protein (Env) complex is made more accessible to antibody binding as a consequence of adaptation to growth in established cell lines. Here, we revisit this question using genetically related PI and TCLA viruses and molecularly cloned env genes. By using complementary …

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Development Of Microsatellite Multiplexes For Wild Goats Using Primers Designed From Domestic Bovidae, Celia Maudet, Gordon Luikart, Pierre Taberlet Jan 2001

Development Of Microsatellite Multiplexes For Wild Goats Using Primers Designed From Domestic Bovidae, Celia Maudet, Gordon Luikart, Pierre Taberlet

Biological Sciences Faculty Publications

Many wild goat taxa (Capra spp.) are endangered and would benefit from the availability of molecular tools that are useful for population management and conservation. We developed microsatellite DNA markers useful in all wild goat species, by using a cross-species amplification approach. Seventy-five microsatellite primer pairs designed from domestic cattle (Bos taurus), sheep (Ovis aries) and goat (Capra hircus) were tested oil three distantly related Capra species: C. ibex ibex, C. [i.] sibirica, and C. pyrenaica. On average, 90% of the domestic ungulate primers amplified a microsatellite PCR product in the …

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Hemin-Binding Surface Protein From Bartonella Quintana, James A. Carroll, Sherry A. Coleman, Laura S. Smitherman, Michael F. Minnick Dec 2000

Hemin-Binding Surface Protein From Bartonella Quintana, James A. Carroll, Sherry A. Coleman, Laura S. Smitherman, Michael F. Minnick

Biological Sciences Faculty Publications

Bartonella quintana, the agent of trench fever and a cause of endocarditis and bacillary angiomatosis in humans, has the highest reported in vitro hemin requirement for any bacterium. We determined that eight membrane-associated proteins from B. quintana bind hemin and that a similar to 25-kDa protein (HbpA) was the dominant hemin binding protein. Like many outer membrane proteins, HbpA partitions to the detergent phase of a Triton X-114 extract of the cell and is heat modifiable, displaying an apparent molecular mass shift from approximately 25 to 30 kDa when solubilized at 100 degreesC. Immunoblots of purified outer and inner membranes …

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Characterization Of Borrelia Burgdorferi Blya And Blyb Proteins: A Prophage-Encoded Holin-Like System, Christopher J. Damman, Christian H. Eggers, D. Scott Samuels Dec 2000

Characterization Of Borrelia Burgdorferi Blya And Blyb Proteins: A Prophage-Encoded Holin-Like System, Christopher J. Damman, Christian H. Eggers, D. Scott Samuels

Biological Sciences Faculty Publications

The conserved cp32 plasmid family of Borrelia burgdorferi was recently shown to be packaged into a bacteriophage particle (C. H. Eggers and D. S. Samuels, J. Bacteriol. 181:7308-7313, 1999), This plasmid encodes BlyA, a 7.4-kDa membrane-interactive protein, and BlyB, an accessory protein, which were previously proposed to comprise a hemolysis system. Our genetic and biochemical evidence suggests that this hypothesis is incorrect and that BlyA and BlyB function instead as a prophage-encoded holin or holin-like system for this newly described bacteriophage, An Escherichia coli mutant containing the blyAB locus that was defective for the normally cryptic host hemolysin SheA was …

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Long-Toed Salamanders In Harvested And Intact Douglas-Fir Forests Of Western Montana, George P. Naughton, Colin B. Henderson, Kerry R. Foresman, Rex L. Mcgraw Ii Dec 2000

Long-Toed Salamanders In Harvested And Intact Douglas-Fir Forests Of Western Montana, George P. Naughton, Colin B. Henderson, Kerry R. Foresman, Rex L. Mcgraw Ii

Biological Sciences Faculty Publications

There is little known about how timber harvest practices have affected terrestrial amphibians in the northern Rocky Mountains. Especially lacking is information on the effects of revised harvest methods that fall within the framework of environmental or New Forestry. We estimated the relative abundance of a common forest amphibian, the long-toed salamander (Ambystoma macrodactylum) captured in pitfall arrays on intact, environmentally harvested, and overstory-removal harvested sites in mixed-conifer forests of western Montana. Pitfall data from 1994 through 1996 showed that previously logged sites contained significantly fewer long-toed salamanders regardless of harvest method used. The number of salamanders captured …

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Sensitivity Of Species Habitat-Relationship Model Performance To Factors Of Scale, J. W. Karl, P. J. Heglund, E. O. Garton, J. M. Scott, N. M. Wright, Richard L. Hutto Dec 2000

Sensitivity Of Species Habitat-Relationship Model Performance To Factors Of Scale, J. W. Karl, P. J. Heglund, E. O. Garton, J. M. Scott, N. M. Wright, Richard L. Hutto

Biological Sciences Faculty Publications

Researchers have come to different conclusions about the usefulness of habitat-relationship models for predicting species presence or absence. This difference frequently stems from a failure to recognize the effects of spatial scales at which the models are applied. We examined the effects of model complexity, spatial data resolution, and scale of application on the performance of bird habitat relationship (BHR) models on the Craig Mountain Wildlife Management Area and on the Idaho portion of the U.S. Forest Service's Northern Region. We constructed and tested BHR models for 60 bird species detected on the study areas. The models varied by three …

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Monitoring Bacterial Transport By Stable Isotope Enrichment Of Cells, William Holben, Peggy H. Ostrom Nov 2000

Monitoring Bacterial Transport By Stable Isotope Enrichment Of Cells, William Holben, Peggy H. Ostrom

Biological Sciences Faculty Publications

Understanding the transport and behavior of bacteria in the environment has broad implications in diverse areas, ranging from agriculture to groundwater quality, risk assessment, and bioremediation. The ability to reliably track and enumerate specific bacterial populations in the context of native communities and environments is key to developing this understanding. We report a novel bacterial tracking approach, based on altering the stable carbon isotope value (delta C-13) Of bacterial cells, which provides specific and sensitive detection and quantification of those cells in environmental samples. This approach was applied to the study of bacterial transport in saturated porous media. The transport …

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Facilitation May Buffer Competitive Effects: Indirect And Diffuse Interactions Among Salt Marsh Plants, Ragan M. Callaway, Steven C. Pennings Oct 2000

Facilitation May Buffer Competitive Effects: Indirect And Diffuse Interactions Among Salt Marsh Plants, Ragan M. Callaway, Steven C. Pennings

Biological Sciences Faculty Publications

Direct interactions among plant species may be highly modified by indirect or diffuse effects within a multispecies community. We investigated the direct and diffuse effects of two salt marsh perennials, Monanthechloe littoralis and Arthrocnemum subterminale, on winter annuals and the perennial herb Limonium californicum in a salt marsh in central California. In permanent plots, Monanthechloe had expanded substantially in the upper marsh over the past 13 yr, while Arthrocnemum and all annual species had decreased. These dynamics suggest that Monanthechloe may directly outcompete most other species in the upper marsh. In contrast, Arthrocnemum is known to facilitate some annual species. …

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A Biochemical Mechanism For Nonrandom Mutations And Evolution, Barbara E. Wright Jun 2000

A Biochemical Mechanism For Nonrandom Mutations And Evolution, Barbara E. Wright

Biological Sciences Faculty Publications

No abstract provided.

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Outcrossing Rate And Inbreeding Depression In The Perennial Yellow Bush Lupine, Lupinus Arboreus (Fabaceae), Pamela Kittelson, John L. Maron May 2000

Outcrossing Rate And Inbreeding Depression In The Perennial Yellow Bush Lupine, Lupinus Arboreus (Fabaceae), Pamela Kittelson, John L. Maron

Biological Sciences Faculty Publications

Little is known about the breeding systems of perennial Lupinus species. We provide information about the breeding system of the perennial yellow bush lupine, Lupinus arboreus, specifically determining self-compatibility, outcrossing rate, and level of inbreeding depression. Flowers are self-compatible, but autonomous self-fertilization rarely occurs; thus selfed seed are a product of facilitated selfing. Based on four isozyme loci from 34 maternal progeny arrays of seeds we estimated an outcrossing rate of 0.78. However, when we accounted for differential maturation of selfed seeds, the outcrossing rate at fertilization was lower, ∼0.64. Fitness and inbreeding depression of 11 selfed and outcrossed families …

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The Impacts Of A Nonindigenous Marine Predator In A California Bay, Edwin D. Grosholz, Gregory M. Ruiz, Cheryl A. Dean, Kim A. Shirley, John L. Maron, Peter G. Connors May 2000

The Impacts Of A Nonindigenous Marine Predator In A California Bay, Edwin D. Grosholz, Gregory M. Ruiz, Cheryl A. Dean, Kim A. Shirley, John L. Maron, Peter G. Connors

Biological Sciences Faculty Publications

Coastal marine ecosystems worldwide are being altered rapidly by the invasion of nonindigenous species. Unlike terrestrial and freshwater systems, the impacts of an invading species have never been quantified on multiple trophic levels for a marine food web. We measured the impact of the nonindigenous green crab, Carcinus maenas, on a coastal marine food web in central California and found that this predator exerted strong “top-down” control, significantly reducing the abundances of several of the 20 invertebrate species monitored over a 9-yr period. Densities of native clams, Nutricola tantilla and Nutricola confusa, and native shore crabs, Hemigrapsus oregonensis, showed 5-fold …

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Integrating Development With Evolution: A Case Study With Beetle Horns, Douglas J. Emlen May 2000

Integrating Development With Evolution: A Case Study With Beetle Horns, Douglas J. Emlen

Biological Sciences Faculty Publications

No abstract provided.

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Disruption Of The Borrelia Burgdorferi Gac Gene, Encoding The Naturally Synthesized Gyra C-Terminal Domain, Scott W. Knight, Betsy J. Kimmel, Christian H. Eggers, D. Scott Samuels Apr 2000

Disruption Of The Borrelia Burgdorferi Gac Gene, Encoding The Naturally Synthesized Gyra C-Terminal Domain, Scott W. Knight, Betsy J. Kimmel, Christian H. Eggers, D. Scott Samuels

Biological Sciences Faculty Publications

The C-terminal domain of the A subunit of DNA gyrase, which we term Gac, is naturally synthesized in Borrelia burgdorferi as an abundant DNA-binding protein. Full-length GyrA, which includes the C-terminal domain, is also synthesized by the spirochete and functions as a subunit of DNA gyrase, We have disrupted synthesis of Gac as an independent protein and demonstrated that it is not essential for growth in a coumarin-resistant background. We detected no alterations in DNA maintenance, condensation, or topology In B. burgdorferi lacking this small DNA-binding protein.

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A Bacteriophage-Like Particle From Bartonella Bacilliformis, Kent D. Barbian, Michael F. Minnick Mar 2000

A Bacteriophage-Like Particle From Bartonella Bacilliformis, Kent D. Barbian, Michael F. Minnick

Biological Sciences Faculty Publications

Bartonella bacilliformis and Bartonella henselae, the respective agents of Oroya fever and cat-scratch disease in humans, are known to produce bacteriophage-like particles (BLPs) that package 14 kbp segments of the host chromosome. Data from this study suggest that other Bartonella species including Bartonella quintana, Bartonella doshiae and Bartonella grahamii also contain similar BLPs, as evidenced by the presence of a 14 kbp extrachromosomal DNA element in their genomes, whereas Bartonella elizabethae and Bartonella clarridgeiae do not. A purification scheme utilizing chloroform, DNase I and centrifugation was devised to isolate BLPs from B. bacilliformis. Intact BLPs were observed by transmission electron …

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The Advantages Of Clonal Integration Under Different Ecological Conditions: A Community-Wide Test, Steven C. Pennings, Ragan M. Callaway Mar 2000

The Advantages Of Clonal Integration Under Different Ecological Conditions: A Community-Wide Test, Steven C. Pennings, Ragan M. Callaway

Biological Sciences Faculty Publications

The "connectedness" of clonal plants has been shown to promote survival and growth in a variety of single-species, single-factor studies, but experiments comparing the relative advantages of clonality across multiple habitats and species are rare, raising the concern that generalizations about the benefits of clonality might be biased by the particular species or habitat studied. We studied the importance of clonal integration in southeastern USA salt marsh plants, using all six of the common clonal species in the community, by following the success of intact and severed clonal fragments invading three habitat treatments. Clonal integration was most important for growth …

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Genetic Variation Among Endosymbionts Of Widely Distributed Vestimentiferan Tubeworms, Carol A. Di Meo, Ami E. Wilbur, William E. Holben, Robert A. Feldman, Robert C. Vrijenhoek, S. Craig Cary Feb 2000

Genetic Variation Among Endosymbionts Of Widely Distributed Vestimentiferan Tubeworms, Carol A. Di Meo, Ami E. Wilbur, William E. Holben, Robert A. Feldman, Robert C. Vrijenhoek, S. Craig Cary

Biological Sciences Faculty Publications

Vestimentiferan tubeworms thriving in sulfidic deep-sea hydrothermal vents and cold seeps are constrained by their nutritional reliance on chemoautotrophic endosymbionts. In a recent phylogenetic study using 16S ribosomal DNA, we found that endosymbionts from vent and seep habitats form two distinct clades,vith little variation within each clade. In the present study, we used two different approaches to assess the genetic variation among biogeographically distinct vestimentiferan symbionts, DNA sequences were obtained for the noncoding, internal transcribed spacer (ITS) regions of the rRNA operons of symbionts associated with six different genera of vestimentiferan tubeworms. ITS sequences from endosymbionts of host genera collected …

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Stress And Developmental Stability: Vegetation Removal Causes Increased Fluctuating Asymmetry In Shrews, Alexander V. Badyaev, Kerry R. Foresman, Miguel V. Fernandes Feb 2000

Stress And Developmental Stability: Vegetation Removal Causes Increased Fluctuating Asymmetry In Shrews, Alexander V. Badyaev, Kerry R. Foresman, Miguel V. Fernandes

Biological Sciences Faculty Publications

Environmental stress can increase phenotypic variation in populations by affecting developmental stability of individuals. While such increase in variation results from individual differences in ability to buffer stress, groups of individuals and different traits may have different sensitivity to stressful conditions. For example, the sex that is under stronger directional selection for faster growth may be more sensitive to stressful conditions during development. On an individual level, stress-induced variation in a trait may be related to the strength of stabilizing selection that acts on the trait. We experimentally examined sensitivity of mandibular development to stress in a free-living population of …

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Structure Of A Rat Α1-Macroglobulin Receptor-Binding Domain Dimer, Tsan Xiao, Dianne L. Decamp, Stephen R. Sprang Jan 2000

Structure Of A Rat Α1-Macroglobulin Receptor-Binding Domain Dimer, Tsan Xiao, Dianne L. Decamp, Stephen R. Sprang

Biological Sciences Faculty Publications

α-Macroglobulin inhibits a broad spectrum of proteinases by forming macromolecular cages inside which proteinases are cross-linked and trapped. Upon formation of a complex with proteinase, α-macroglobulin undergoes a large conformational change that results in the exposure of its receptor-binding domain (RBD). Engagement of this domain by α-macroglobulin receptor permits clearance of the α-macroglobulin: proteinase complex from circulation. The crystal structure of rat α1-macroglobulin RBD has been determined at 2.3 Å resolution. The RBD is composed of a nine-stranded β-sandwich and a single α-helix that has been implicated as part of the receptor binding site and that lies on …

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