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Articles 331 - 360 of 602

Full-Text Articles in Biology

Stress Responses In Tropical Sparrows: Comparing Tropical And Temperate Zonotrichia, Haruka Wada, Ignacio T. Moore, Creagh W. Breuner, John C. Wingfield Jul 2006

Stress Responses In Tropical Sparrows: Comparing Tropical And Temperate Zonotrichia, Haruka Wada, Ignacio T. Moore, Creagh W. Breuner, John C. Wingfield

Biological Sciences Faculty Publications

Seasonal modulation of the adrenocortical response appears to be ubiquitous in mid- to high- latitude vertebrates but has not been investigated in tropical vertebrates. Previous studies demonstrate that temperate passerines show seasonality in corticosterone secretion and corticosteroid binding globulin capacities. We examined seasonal and sex differences in the stress response in an equatorial population of Zonotrichia capensis, the only Zonotrichia that breeds in the tropics, and compared the results with those of northern Zonotrichia. Seasonal differences in tropical Zonotrichia would presumably be independent of photoperiod and thus directly related to such activities as reproduction and feather molt. In addition, we …

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Linking Scales In Stream Ecology, Winsor H. Lowe, Gene E. Likens, Mary E. Power Jul 2006

Linking Scales In Stream Ecology, Winsor H. Lowe, Gene E. Likens, Mary E. Power

Biological Sciences Faculty Publications

The hierarchical structure of natural systems can be useful in designing ecological studies that are informative at multiple spatial scales. Although stream systems have long been recognized as having a hierarchical spatial structure, there is a need for more empirical research that exploits this structure to generate an understanding of population biology, community ecology, and species-ecosystem linkages across spatial scales. We review studies that link pattern and process across multiple scales of stream-habitat organization, highlighting the insight derived from this multiscale approach and the role that mechanistic hypotheses play in its successful application. We also describe afrontier in stream research …

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Facilitation By Pinus Flexilis During Succession: A Hierarchy Of Mechanisms Benefits Other Plant Species, Dayna Baumeister, Ragan M. Callaway Jul 2006

Facilitation By Pinus Flexilis During Succession: A Hierarchy Of Mechanisms Benefits Other Plant Species, Dayna Baumeister, Ragan M. Callaway

Biological Sciences Faculty Publications

Studies of facilitation have primarily been limited to single mechanisms, species, or environments. We examined interacting mechanisms governing the facilitative effects of Pinus flexilis on two later successional understory species, Pseudotsuga menziesii and Ribes cereum, in different microhabitats and seasons at the ecotone between the Rocky Mountain forests and Great Plains grasslands in Montana, USA. In field surveys, 69% of Pseudotsuga and 91% of Ribes were located beneath P. flexilis even though P. flexilis subcrowns accounted for a small proportion of available habitat. For three years, we monitored the survival of Pseudotsuga and Ribes seedlings experimentally planted beneath …

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Estimating Detection Probablities Of River Birds Using Double Surveys, Robert J. Fletcher Jr., Richard L. Hutto Jul 2006

Estimating Detection Probablities Of River Birds Using Double Surveys, Robert J. Fletcher Jr., Richard L. Hutto

Biological Sciences Faculty Publications

We describe a method for surveying birds in river habitats that allows for rapid assessment across broad spatial scales and estimation of detection probabilities. Our river survey approach incorporates a double-survey technique, whereby observers in two canoes simultaneously survey birds along a river reach. Data are in the form of a two-sample mark-recapture history, and covariates suspected of influencing detection probabilities can be included in the modeling process and evaluated using information-theoretic approaches. We provide an example using the method along the Madison and upper Missouri rivers in Montana. Overall, detection probabilities for each observer ranged from 57% to 89%, …

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Environmental Signals Generate A Differential And Coordinated Expression Of The Heme Receptor Gene Family Of Bartonella Quintana, James M. Battisti, Kate N. Sappington, Laura S, Smitherman, Nermi L. Parrow, Michael F. Minnick Jun 2006

Environmental Signals Generate A Differential And Coordinated Expression Of The Heme Receptor Gene Family Of Bartonella Quintana, James M. Battisti, Kate N. Sappington, Laura S, Smitherman, Nermi L. Parrow, Michael F. Minnick

Biological Sciences Faculty Publications

Of all bacteria, Bartonella quintana has the highest reported in vitro hemin requirement, yet an explanation for this remains elusive. To produce diseases such as trench fever, endocarditis, and bacillary angiomatosis, B. quintana must survive and replicate in the disparate environments of the Pediculus humanus corporis (body louse) gut and the human vasculature. We previously identified a five-member family of hemin binding proteins (Hbps) synthesized by B. quintana that bind hemin on the outer surface but share no similarity to known bacterial heme receptors. In the present study, we examine the transcription, regulation, and synthesis of this virulence factor family …

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Role Of The Stable Signal Peptide And Cytoplasmic Domain Of G2 In Regulating Intracellular Transport Of The Junín Virus Envelope Glycoprotein Complex, Sudhakar S. Agnihothram, Joanne York, Jack H. Nunberg Jun 2006

Role Of The Stable Signal Peptide And Cytoplasmic Domain Of G2 In Regulating Intracellular Transport Of The Junín Virus Envelope Glycoprotein Complex, Sudhakar S. Agnihothram, Joanne York, Jack H. Nunberg

Biological Sciences Faculty Publications

Enveloped viruses utilize the membranous compartments of the host cell for the assembly and budding of new virion particles. In this report, we have investigated the biogenesis and trafficking of the envelope glycoprotein (GP-Q of the Junin arenavirus. The mature GP-C complex is unusual in that it retains a stable signal peptide (SSP) as an essential component in association with the typical receptor-binding (G1) and transmembrane fusion (G2) subunits. We demonstrate that, in the absence of SSP, the G1-G2 precursor is restricted to the endoplasmic reticulum (ER). This constraint is relieved by coexpression of SSP in trans, allowing transit of …

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Unexpected Diversity And Complexity Of The Guerrero Negro Hypersaline Microbial Mat, Ruth E. Ley, J. Kirk Harris, Joshua Wilcox, John R. Spear, Scott R. Miller, Brad M. Bebout, Julia A. Maresca, Donald A. Bryant, Mithcell L. Sogin, Norman R. Pace May 2006

Unexpected Diversity And Complexity Of The Guerrero Negro Hypersaline Microbial Mat, Ruth E. Ley, J. Kirk Harris, Joshua Wilcox, John R. Spear, Scott R. Miller, Brad M. Bebout, Julia A. Maresca, Donald A. Bryant, Mithcell L. Sogin, Norman R. Pace

Biological Sciences Faculty Publications

We applied nucleic acid-based molecular methods, combined with estimates of biomass (ATP), pigments, and microelectrode measurements of chemical gradients, to map microbial diversity vertically on a millimeter scale in a hypersaline microbial mat from Guerrero Negro, Baja California Sur, Mexico. To identify the constituents of the mat, small-subunit rRNA genes were amplified by PCR from community genomic DNA extracted from layers, cloned, and sequenced. Bacteria dominated the mat and displayed unexpected and unprecedented diversity. The majority (1,336) of the 1,586 bacterial 16S rRNA sequences generated were unique, representing 752 species (>= 97% rRNA sequence identity) in 42 of the …

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What Use Is Half A Wing In The Ecology And Evolution Of Birds?, Kenneth P. Dial, Ross J. Randall, Terry R. Dial May 2006

What Use Is Half A Wing In The Ecology And Evolution Of Birds?, Kenneth P. Dial, Ross J. Randall, Terry R. Dial

Biological Sciences Faculty Publications

The use of incipient wings during ontogeny in living birds reveals not only the function of these developing forelimbs in growing birds’ survival but also the possible employment of protowings during transitional stages in the evolution of flight. When startled, juvenile galliform birds attempt aerial flight even though their wings are not fully developed. They also flap their incipient wings when they run up precipitous inclines, a behavior we have described as wing-assisted incline running (WAIR), and when they launch from elevated structures. The functional benefit of beating these protowings has only recently been evaluated. We report the first ontogenetic …

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A Framework For Understanding Ecological Traps And An Evaluation Of Existing Evidence, Bruce A. Robertson, Richard L. Hutto May 2006

A Framework For Understanding Ecological Traps And An Evaluation Of Existing Evidence, Bruce A. Robertson, Richard L. Hutto

Biological Sciences Faculty Publications

When an animal settles preferentially in a habitat within which it does poorly relative to other available habitats, it is said to have been caught in an “ecological trap.” Although the theoretical possibility that animals may be so trapped is widely recognized, the absence of a clear mechanistic understanding of what constitutes a trap means that much of the literature cited as support for the idea may be weak, at best. Here, we develop a conceptual model to explain how an ecological trap might work, outline the specific criteria that are necessary for demonstrating the existence of an ecological trap, …

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Invasive Plant Suppresses The Growth Of Native Tree Seedlings By Disrupting Belowground Mutualisms, Kristina A. Stinson, Stuart A. Campbell, Jeff R. Powell, Benjamin E. Wolfe, Ragan M. Callaway, Giles C. Thelen, Steven G. Hallett, Daniel Prati, John N. Klironomos May 2006

Invasive Plant Suppresses The Growth Of Native Tree Seedlings By Disrupting Belowground Mutualisms, Kristina A. Stinson, Stuart A. Campbell, Jeff R. Powell, Benjamin E. Wolfe, Ragan M. Callaway, Giles C. Thelen, Steven G. Hallett, Daniel Prati, John N. Klironomos

Biological Sciences Faculty Publications

The impact of exotic species on native organisms is widely acknowledged, but poorly understood. Very few studies have empirically investigated how invading plants may alter delicate ecological interactions among resident species in the invaded range. We present novel evidence that antifungal phytochemistry of the invasive plant, Alliaria petiolata, a European invader of North American forests, suppresses native plant growth by disrupting mutualistic associations between native canopy tree seedlings and belowground arbuscular mycorrhizal fungi. Our results elucidate an indirect mechanism by which invasive plants can impact native flora, and may help explain how this plant successfully invades relatively undisturbed forest habitat.

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Time For International Policies On Biological Invasions, Inderjit, Ragan M. Callaway, Shalini Kaushik Mar 2006

Time For International Policies On Biological Invasions, Inderjit, Ragan M. Callaway, Shalini Kaushik

Biological Sciences Faculty Publications

No abstract provided.

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Mutations Conferring Aminoglycoside And Spectinomycin Resistance In Borrelia Burgdorferi, Daniel Criswell, Virginia L. Tobiason, J. Stephen Lodmell, D. Scott Samuels Feb 2006

Mutations Conferring Aminoglycoside And Spectinomycin Resistance In Borrelia Burgdorferi, Daniel Criswell, Virginia L. Tobiason, J. Stephen Lodmell, D. Scott Samuels

Biological Sciences Faculty Publications

We have isolated and characterized in vitro mutants of the Lyme disease agent Borrelia burgdorferi that are resistant to spectinomycin, kanamycin, gentamicin, or streptomycin, antibiotics that target the small subunit of the ribosome. 16S rRNA mutations A1185G and C1186U, homologous to Escherichia coli nucleotides A1191 and C1192, conferred > 2,200-fold and 1,300-fold resistance to spectinomycin, respectively. A 16S rRNA A1402G mutation, homologous to E. coli A1408, conferred > 90-fold resistance to kanamycin and > 240-fold resistance to gentamicin. Two mutations were identified in the gene for ribosomal protein S12, at a site homologous to E. coli residue Lys-87, in mutants selected in streptomycin. …

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Linking Direct And Indirect Data On Dispersal: Isolation By Slope In A Headwater Stream Salamander, Winsor H. Lowe, Gene E. Likens, Mark A. Mcpeek, Don C. Buso Feb 2006

Linking Direct And Indirect Data On Dispersal: Isolation By Slope In A Headwater Stream Salamander, Winsor H. Lowe, Gene E. Likens, Mark A. Mcpeek, Don C. Buso

Biological Sciences Faculty Publications

There is growing recognition of the need to incorporate information on movement behavior in landscape-scale studies of dispersal. One way to do this is by using indirect indices of dispersal (e.g., genetic differentiation) to test predictions derived from direct data on movement behavior. Mark–recapture studies documented upstream-biased movement in the salamander Gyrinophilus porphyriticus (Plethodontidae). Based on this information, we hypothesized that gene flow in G. porphyriticus is affected by the slope of the stream. Specifically, because the energy required for upstream dispersal is positively related to slope, we predicted gene flow to be negatively related to change in elevation between …

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An Introduced Predator Alters Aleutian Island Plant Communities By Thwarting Nutrient Subsidies, John L. Maron, James A. Estes, Donald A. Croll, Eric M. Danner, Sarah C. Elmendorf, Stacey L. Buckelew Feb 2006

An Introduced Predator Alters Aleutian Island Plant Communities By Thwarting Nutrient Subsidies, John L. Maron, James A. Estes, Donald A. Croll, Eric M. Danner, Sarah C. Elmendorf, Stacey L. Buckelew

Biological Sciences Faculty Publications

The ramifying effects of top predators on food webs traditionally have been studied within the framework of trophic cascades. Trophic cascades are compelling because they embody powerful indirect effects of predators on primary production. Although less studied, indirect effects of predators may occur via routes that are not exclusively trophic. We quantified how the introduction of foxes onto the Aleutian Islands transformed plant communities by reducing abundant seabird populations, thereby disrupting nutrient subsidies vectored by seabirds from sea to land. We compared soil and plant fertility, plant biomass and community composition, and stable isotopes of nitrogen in soil, plants, and …

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Mechanisms Of Genotoxin-Induced Transcription And Hypermutation In P53, Barbara E. Wright, Jacqueline Reimers, Karen Schmidt, Evan Burkala, Ping Wei, Ping Wei Jan 2006

Mechanisms Of Genotoxin-Induced Transcription And Hypermutation In P53, Barbara E. Wright, Jacqueline Reimers, Karen Schmidt, Evan Burkala, Ping Wei, Ping Wei

Biological Sciences Faculty Publications

It is widely assumed that genotoxin-induced damage (e.g., G-to-T transversions) to the tumor suppressor gene, p53, is a direct cause of cancer. However, genotoxins also induce the stress response, which upregulates p53 transcription and the formation of secondary structures from ssDNA. Since unpaired bases are thermodynamically unstable and intrinsically mutable, increased transcription could be the cause of hypermutation, and thus cancer. Support for this hypothesis has been obtained by analyzing 6662 mutations in all types of cancer compared to lung and colon cancers, using the p53 mutation database. The data suggest that genotoxins have two independent effects: first, they induce …

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Occurrence, Persistence, And Expansion Of Saltcedar (Tamarix Spp.) Populations In The Great Plains Of Montana, Jason P. Sexton, Anna Sala, Kevin Murray Jan 2006

Occurrence, Persistence, And Expansion Of Saltcedar (Tamarix Spp.) Populations In The Great Plains Of Montana, Jason P. Sexton, Anna Sala, Kevin Murray

Biological Sciences Faculty Publications

Saltcedar (Tamarix spp.), a shrub native to Eurasia, is associated with major alterations to wetland and riparian systems in the southwestern United States. Since the 1960s saltcedar has been naturalized in northern states of the U.S. where its growth potential and impacts are not well known. Here, we describe the occurrence, age, size, and relative cover of saltcedar populations in several river basins in central eastern Montana, USA, to identify potential patterns of spread across the region and changes in individual populations as they age. Stands were aged according to the oldest saltcedar individuals and were sampled for dominant plant …

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Northern Region Landbird Monitoring Program: A Usfs-University Of Montana Partnership Designed To Provide Both Short-Term And Long-Term Feedback For Land Managers, Richard L. Hutto, Skip Kowalski Jan 2006

Northern Region Landbird Monitoring Program: A Usfs-University Of Montana Partnership Designed To Provide Both Short-Term And Long-Term Feedback For Land Managers, Richard L. Hutto, Skip Kowalski

Biological Sciences Faculty Publications

The Northern Region Landbird Monitoring Program (NRLMP) began in 1990 as a cooperative effort between the United States Forest Service (USFS) and the University of Montana. The combination of a research-oriented perspective from the University and a management-needs perspective from the National Forests within the Northern Region led to the realization that landbirds as a group might serve as a powerful tool to address more widespread monitoring needs in the USFS Northern Region. The program quickly evolved from one that was put into place specifically to use federally earmarked dollars to address neotropical migratory bird conservation, into a more general …

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Habitat-Specific Impacts Of Multiple Consumers On Plant Population Dynamics, John L. Maron, Matthew J. Kauffman Jan 2006

Habitat-Specific Impacts Of Multiple Consumers On Plant Population Dynamics, John L. Maron, Matthew J. Kauffman

Biological Sciences Faculty Publications

Multiple consumers often attack seeds, seedlings, and adult plants, but their population-level consequences remain uncertain. We examined how insect and small mammal consumers influenced the demography and abundance of the perennial shrub, bush lupine (Lupinus arboreus). In grassland and dune habitats we established replicate experimental lupine populations in 81-m2 plots that were either protected from, or exposed to, herbivorous voles and granivorous mice (via fencing) and/or root feeding insects (via insecticide treatment). Populations were initiated with transplanted seedlings in 1999 and 2000. We followed the demography of these cohorts, subsequent generations, and the seed bank for 5.5 …

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Bartonella Bacilliformis Groel: Effect On Growth Of Human Vascular Endothelial Cells In Infected Cocultures, Laura S. Smitherman, Michael F. Minnick Dec 2005

Bartonella Bacilliformis Groel: Effect On Growth Of Human Vascular Endothelial Cells In Infected Cocultures, Laura S. Smitherman, Michael F. Minnick

Biological Sciences Faculty Publications

Bartonella are the only bacteria known to induce angioproliferative lesions of the human vasculature and liver during infection. Previous work from our lab suggests that GroEL participates in the mitogenic response observed in HUVEC cultures supplemented with the soluble fraction of Bartonella bacilliformis. Work in this study shows that exposure to high concentrations of the fraction is actually cytotoxic for HUVECs. To analyze this phenomenon, live B. bacilliformis-HUVEC cocultures were employed to study the effect of excess bacterial GroEL on the host cell during active infection. Four B. bacilliformis strains were generated to produce varying levels of GroEL. HUVEC cocultures …

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Evolution Of Sexual Dimorphism And Male Dimorphism In The Expression Of Beetle Horns: Phylogenetic Evidence For Modularity, Evolutionary Lability, And Constraint, Douglas J. Emlen, John Hunt, Leigh W. Simmons Oct 2005

Evolution Of Sexual Dimorphism And Male Dimorphism In The Expression Of Beetle Horns: Phylogenetic Evidence For Modularity, Evolutionary Lability, And Constraint, Douglas J. Emlen, John Hunt, Leigh W. Simmons

Biological Sciences Faculty Publications

Beetle horns are enlarged outgrowths of the head or thorax that are used as weapons in contests over access to mates. Horn development is typically confined to males (sexual dimorphism) and often only to the largest males (male dimorphism). Both types of dimorphism result from endocrine threshold mechanisms that coordinate cell proliferation near the end of the larval period. Here, we map the presence/absence of each type of dimorphism onto a recent phylogeny for the genus Onthophagits (Coleoptera: Scarabaeidae) to explore how horn development has changed over time. Our results provide empirical support for several recent predictions regarding the evolutionary …

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Parc Mutations In Fluoroquinolone-Resistant Borrelia Burgdorfeti, Kendal M. Galbraith, Amanda C. Ng, Betsy J. Eggers, Craig R. Kuchel, Christian H. Eggers, D. Scott Samuels Oct 2005

Parc Mutations In Fluoroquinolone-Resistant Borrelia Burgdorfeti, Kendal M. Galbraith, Amanda C. Ng, Betsy J. Eggers, Craig R. Kuchel, Christian H. Eggers, D. Scott Samuels

Biological Sciences Faculty Publications

We have isolated in vitro fluoroquinolone-resistant mutants of the Lyme disease agent, Borrelia burgdorferi. Mutations in parC, which encodes a subunit of topoisomerase IV, were associated with loss of susceptibility to sparfloxacin, moxifloxacin, and Bay-Y3118, but not ciprofloxacin. This is the first description of fluoroquinolone resistance in the spirochete phylum.

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Characterization And Expression Analysis Of The Groesl Operon Of Bartonella Bacilliformis, Julie A. Callison, James M. Battisti, Kate N. Sappington, Laura S. Smitherman, Michael F. Minnick Oct 2005

Characterization And Expression Analysis Of The Groesl Operon Of Bartonella Bacilliformis, Julie A. Callison, James M. Battisti, Kate N. Sappington, Laura S. Smitherman, Michael F. Minnick

Biological Sciences Faculty Publications

The groESL operon of Bartonella bacilliformis, a facultative intracellular, Gram-negative bacterium and etiologic agent of Oroya Fever, was characterized. Sequence analysis revealed an operon containing two genes of 294 (groES) and 1632 nucleotides (groEL) separated by a 55-nt intergenic spacer. The operon is preceded by a 72-nt ORF (ORF1) that encodes a hypothetical protein with homology to a portion of the HrcA repressor for groESL. A divergent fumarate hydratase C (fumC) gene lies further upstream. Deduced amino acid sequences for B. bacilliformis GroEL and GroES revealed a high degree of identity with homologues from other Bartonella and alpha-Protebacteria. A single …

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Changes In Bird Abundance After Wildfire: Importance Of Fire Severity And Time Since Fire, Kristina M. Smucker, Richard L. Hutto, Brian M. Steele Oct 2005

Changes In Bird Abundance After Wildfire: Importance Of Fire Severity And Time Since Fire, Kristina M. Smucker, Richard L. Hutto, Brian M. Steele

Biological Sciences Faculty Publications

Fire can cause profound changes in the composition and abundance of plant and animal species, but logistics, unpredictability of weather, and inherent danger make it nearly impossible to study high-severity fire effects experimentally. We took advantage of a unique opportunity to use a before–after/control–impact (BACI) approach to analyze changes in bird assemblages after the severe fires of 2000 in the Bitterroot Valley, Montana. Observers surveyed birds using 10-minute point counts and collected vegetation data from 13 burned and 13 unburned transects for five years before fire and three years after fire. We compared changes in vegetation variables and relative bird …

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A Peptide Core Motif For Binding To Heterotrimeric G Protein Alpha Subunits, William W. Ja, Anirban Adhikari, Ryan J. Austin, Stephen R. Sprang, Richard W. Roberts Sep 2005

A Peptide Core Motif For Binding To Heterotrimeric G Protein Alpha Subunits, William W. Ja, Anirban Adhikari, Ryan J. Austin, Stephen R. Sprang, Richard W. Roberts

Biological Sciences Faculty Publications

Recently, in vitro selection using mRNA display was used to identify a novel peptide sequence that binds with high affinity to Galpha(i1). The peptide was minimized to a 9-residue sequence (R6A-1) that retains high affinity and specificity for the GDP-bound state of Galpha(i1) and acts as a guanine nucleotide dissociation inhibitor (GDI). Here we demonstrate that the R6A-1 peptide interacts with Galpha subunits representing all four G protein classes, acting as a core motif for Galpha interaction. This contrasts with the consensus G protein regulatory(GPR) sequence, a 28-mer peptide GDI derived from the GoLoco (Galpha(i/0)-Loco interaction)/GPR motif that shares no …

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Evolution Of Morphological Integration: Developmental Accommodation Of Stress-Induced Variation, Alexander V. Badyaev, Kerry R. Foresman, Rebecca L. Young Sep 2005

Evolution Of Morphological Integration: Developmental Accommodation Of Stress-Induced Variation, Alexander V. Badyaev, Kerry R. Foresman, Rebecca L. Young

Biological Sciences Faculty Publications

Extreme environmental change during growth often results in an increase in developmental abnormalities in the morphology of an organism. The evolutionary significance of such stress-induced variation depends on the recurrence of a stressor and on the degree to which developmental errors can be accommodated by an organism's ontogeny without significant loss of function. We subjected populations of four species of soricid shrews to an extreme environment during growth and measured changes in the patterns of integration and accommodation of stress-induced developmental errors in a complex of mandibular traits. Adults that grew under an extreme environment had lower integration of morphological …

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Structural And Molecular Characterization Of A Preferred Protein Interaction Surface On G Protein Beta Gamma Subunits, Tara L. Davis, Tabetha M. Bonacci, Stephen R. Sprang, Alan V. Smrcka Aug 2005

Structural And Molecular Characterization Of A Preferred Protein Interaction Surface On G Protein Beta Gamma Subunits, Tara L. Davis, Tabetha M. Bonacci, Stephen R. Sprang, Alan V. Smrcka

Biological Sciences Faculty Publications

G protein betagamma subunits associate with many binding partners in cellular signaling cascades. In previous work, we used random-peptide phage display screening to identify a diverse family of peptides that bound to a common surface on Gbetagamma subunits and blocked a subset of Gbetagamma effectors. Later studies showed that one of the peptides caused G protein activation through a novel Gbetagamma-dependent, nucleotide exchange-independent mechanism. Here we report the X-ray crystal structure of Gbeta(1)gamma(2) bound to this peptide, SIGK (SIGKAFKILGYPDYD), at 2.7 A resolution. SIGK forms a helical structure that binds the same face of Gbeta(1) as the switch II region …

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Human Activity Mediates A Trophic Cascade Caused By Wolves, Mark Hebblewhite, Clifford A. White, Clifford G. Nietvelt, John A. Mckenzie, Tomas E. Hurd, John M. Fryxell, Suzanne E. Bayley, Paul C. Paquet Aug 2005

Human Activity Mediates A Trophic Cascade Caused By Wolves, Mark Hebblewhite, Clifford A. White, Clifford G. Nietvelt, John A. Mckenzie, Tomas E. Hurd, John M. Fryxell, Suzanne E. Bayley, Paul C. Paquet

Biological Sciences Faculty Publications

Experimental evidence of trophic cascades initiated by large vertebrate predators is rare in terrestrial ecosystems. A serendipitous natural experiment provided an opportunity to test the trophic cascade hypothesis for wolves (Canis lupus) in Banff National Park, Canada. The first wolf pack recolonized the Bow Valley of Banff National Park in 1986. High human activity partially excluded wolves from one area of the Bow Valley (low-wolf area), whereas wolves made full use of an adjacent area (high-wolf area). We investigated the effects of differential wolf predation between these two areas on elk (Cervus elaphus) population density, adult …

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Using Airborne Multispectral Imagery To Evaluate Geomorphic Work Across Floodplains Of Gravel-Bed Rivers, M. S. Lorang, D. C. Whited, Richard F. Hauer, J. S. Kimball, Jack Arthur Stanford Aug 2005

Using Airborne Multispectral Imagery To Evaluate Geomorphic Work Across Floodplains Of Gravel-Bed Rivers, M. S. Lorang, D. C. Whited, Richard F. Hauer, J. S. Kimball, Jack Arthur Stanford

Biological Sciences Faculty Publications

Fluvial processes of cut and fill alluviation and channel abandonment or avulsion are essential for maintaining the ecological health of floodplain ecosystems characteristic of gravel-bed rivers. These dynamic processes shape the floodplain landscape, resulting in a shifting mosaic of habitats, both above and below ground. We present a new and innovative methodology to quantitatively assess the geomorphic work potential necessary to maintain a shifting habitat mosaic for gravel-bed river floodplains. This approach can be used to delineate critical habitats for preservation through land acquisition and conservation easements, often critical elements of river restoration plans worldwide. Spatially explicit modeling of water …

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Analysis Of The Ospc Regulatory Element Controlled By The Rpon-Rpos Regulatory Pathway In Borrelia Burgdorferi, Xiaofeng F. Yang, Meghan C. Lybecker, Utpal Pal, Sophie M. Alani, Jon Blevins, Andrew T. Revel, D. Scott Samuels Jul 2005

Analysis Of The Ospc Regulatory Element Controlled By The Rpon-Rpos Regulatory Pathway In Borrelia Burgdorferi, Xiaofeng F. Yang, Meghan C. Lybecker, Utpal Pal, Sophie M. Alani, Jon Blevins, Andrew T. Revel, D. Scott Samuels

Biological Sciences Faculty Publications

Outer surface lipoprotein C (OspC) is a key virulence factor of Borrelia burgdorferi. ospC is differentially regulated during borrelial transmission from ticks to rodents, and such regulation is essential for maintaining the spirochete in its natural enzootic cycle. Recently, we showed that the expression of ospC in B. burgdorferi is governed by a novel alternative sigma factor regulatory network, the RpoN-RpoS pathway. However, the precise mechanism by which the RpoN-RpoS pathway controls ospC expression has been unclear. In particular, there has been uncertainty regarding whether ospC is controlled directly by RpoS (sigma(s)) or indirectly through a transactivator (induced by RpoS). …

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Unpalatable Plants Protect Neighbors From Grazing And Increase Plant Community Diversity, Ragan M. Callaway, David Kikodze, Marina Chiboshvili, Liana Khetsuriani Jul 2005

Unpalatable Plants Protect Neighbors From Grazing And Increase Plant Community Diversity, Ragan M. Callaway, David Kikodze, Marina Chiboshvili, Liana Khetsuriani

Biological Sciences Faculty Publications

Tasty plants can be protected from herbivores by unpalatable neighbors. We used experimental exclosures, removal of unpalatable species, and transplants of palatable and unpalatable species in subalpine meadows of the Caucasus Mountains of Georgia to study the effects of two unpalatable species on plant communities. We found that Cirsium obalatum and Veratrum lobelianum, two large native perennial herbs that invade after heavy grazing, had strong facilitative effects on communities through their indirect effects on livestock herbivores. These unpalatable invaders had different effects on community composition when livestock were present than when livestock were excluded. Furthermore, removing Cirsium and Veratrum …

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