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Biological Sciences Faculty Publications

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Articles 841 - 870 of 1156

Full-Text Articles in Biology

Structure Of The P115rhogef Rgrgs Domain-Galpha13/I1 Chimera Complex Suggests Convergent Evolution Of A Gtpase Activator, Zhe Chen, William D. Singer, Paul C. Sternweis, Stephen R. Sprang Feb 2005

Structure Of The P115rhogef Rgrgs Domain-Galpha13/I1 Chimera Complex Suggests Convergent Evolution Of A Gtpase Activator, Zhe Chen, William D. Singer, Paul C. Sternweis, Stephen R. Sprang

Biological Sciences Faculty Publications

p115RhoGEF, a guanine nucleotide exchange factor (GEF) for Rho GTPase, is also a GTPase-activating protein (GAP) for G12 and G13 heterotrimeric Galpha subunits. The GAP function of p115RhoGEF resides within the N-terminal region of p115RhoGEF (the rgRGS domain), which includes a module that is structurally similar to RGS (regulators of G-protein signaling) domains. We present here the crystal structure of the rgRGS domain of p115RhoGEF in complex with a chimera of Galpha13 and Galphai1. Two distinct surfaces of rgRGS interact with Galpha. The N-terminal betaN-alphaN hairpin of rgRGS, rather than its RGS module, forms intimate contacts with the catalytic site …

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Phylogenetic Reconstruction Of Exoristinae Using Molecular Data: A Bayesian Re-Analysis, John O. Stireman Iii Feb 2005

Phylogenetic Reconstruction Of Exoristinae Using Molecular Data: A Bayesian Re-Analysis, John O. Stireman Iii

Biological Sciences Faculty Publications

A few years ago I published the results of a phylogenetic analysis of New World Exoristinae based on molecular data from two genes, 28S rDNA and Elongation Factor 1-alpha (Stireman 2002). In that study I employed parsimony, neighbor joining, and maximum likelihood inference methods to generate phylogenetic reconstructions, and explored a variety of weighting schemes and combinations of the sequence data (i.e. each gene separately and both together). The results of these analyses generally supported recent taxonomic hypotheses (e.g., Herting 1984; Wood 1987; O’Hara and Wood 2004). For example, Tachinidae and Exoristinae were reconstructed as monophyletic in most analyses, as …

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The Genetics Of Ray Pattern Variation In Caenorhabditis Briggsae, Scott Everet Baird, Cynthia R. Davidson, Justin C. Bohrer Jan 2005

The Genetics Of Ray Pattern Variation In Caenorhabditis Briggsae, Scott Everet Baird, Cynthia R. Davidson, Justin C. Bohrer

Biological Sciences Faculty Publications

Background: How does intraspecific variation relate to macroevolutionary change in morphology? This question can be addressed in species in which derived characters are present but not fixed. In rhabditid nematodes, the arrangement of the nine bilateral pairs of peripheral sense organs (rays) in tails of males is often the most highly divergent character between species. The development of ray pattern involves inputs from hometic gene expression patterns, TGFβ signalling, Wnt signalling, and other genetic pathways. In Caenorhabditis briggsae, strain-specific variation in ray pattern has provided an entrée into the evolution of ray pattern. Some strains were fixed for a derived …

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Fecycle: Attempting An Iron Biogeochemical Budget From A Mesoscale Sf6 Tracer Experiment In Unperturbed Low Iron Waters, Robert Michael Mckay, P. W. Boyd, C. S. Law, D. A. Hutchins, E. R. Abraham, P. L. Croot, M. Ellwood, R. D. Frew, M. Hadfield, J. Hall, S. Handy, C. Hare, J. Higgins, P. Hill, K. A. Hunter, K. Leblanc, M. T. Maldonado, C. Mioni, M. Oliver, S. Pickmere, M. Pinkerton, K. Safi, S. Sander, S. A. Sanudo-Wilhelmy, M. Smith, R. Strzepek, A. Tovar-Sanchez, S. W. Wilhelm Jan 2005

Fecycle: Attempting An Iron Biogeochemical Budget From A Mesoscale Sf6 Tracer Experiment In Unperturbed Low Iron Waters, Robert Michael Mckay, P. W. Boyd, C. S. Law, D. A. Hutchins, E. R. Abraham, P. L. Croot, M. Ellwood, R. D. Frew, M. Hadfield, J. Hall, S. Handy, C. Hare, J. Higgins, P. Hill, K. A. Hunter, K. Leblanc, M. T. Maldonado, C. Mioni, M. Oliver, S. Pickmere, M. Pinkerton, K. Safi, S. Sander, S. A. Sanudo-Wilhelmy, M. Smith, R. Strzepek, A. Tovar-Sanchez, S. W. Wilhelm

Biological Sciences Faculty Publications

An improved knowledge of iron biogeochemistry is needed to better understand key controls on the functioning of high-nitrate low-chlorophyll (HNLC) oceanic regions. Iron budgets for HNLC waters have been constructed using data from disparate sources ranging from laboratory algal cultures to ocean physics. In summer 2003 we conducted FeCycle, a 10-day mesoscale tracer release in HNLC waters SE of New Zealand, and measured concurrently all sources (with the exception of aerosol deposition) to, sinks of iron from, and rates of iron recycling within, the surface mixed layer. A pelagic iron budget (timescale of days) indicated that oceanic supply terms (lateral …

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Introduction – Regional Monitoring Programs, Richard L. Hutto, C. John Ralph Jan 2005

Introduction – Regional Monitoring Programs, Richard L. Hutto, C. John Ralph

Biological Sciences Faculty Publications

There is increasing interest in the initiation of regional or statewide monitoring programs that are less extensive than national efforts such as the Breeding Bird Survey. A number of regional programs have been in existence for a decade or more, so the papers in this section represented an effort to bring together the collective experience of the people who had developed these programs, and to hear about the benefits and drawbacks of their particular designs. Speakers reviewed why they felt there was a need for a regional monitoring effort, examined the designs and response variables associated with their regional monitoring …

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Monitoring For Adaptive Management In Coniferous Forests Of The Northern Rockies, Jock S. Young, John R. Hoffland, Richard L. Hutto Jan 2005

Monitoring For Adaptive Management In Coniferous Forests Of The Northern Rockies, Jock S. Young, John R. Hoffland, Richard L. Hutto

Biological Sciences Faculty Publications

Monitoring can and should be much more than the effort to track population trends; it can be a proactive effort to understand the effects of human activities on bird populations. It should be an integral part of the adaptive management process. With this in mind, the Northern Region Landbird Monitoring Program has a dual focus: (1) to monitor long-term bird population trends, and (2) to study bird-habitat relationships and management effects. By conducting permanent, longterm monitoring transects every other year, we are free to use the intervening years to study the effects of specific management activities. The coordination and funding …

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Fire On The Mountain: Birds And Burns In The Rocky Mountains, Natasha B. Kotliar, Victoria A. Saab, Richard L. Hutto Jan 2005

Fire On The Mountain: Birds And Burns In The Rocky Mountains, Natasha B. Kotliar, Victoria A. Saab, Richard L. Hutto

Biological Sciences Faculty Publications

No abstract provided.

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Demonstration Of Toxicity To Fish And To Mammalian Cells By Pfiesteria Species: Comparison Of Assay Methods And Strains, Joann M. Burkholder, Andrew S. Gordon, Peter D. Moeller, J. Mac Law, Kathryn J. Coyne, Alan J. Lewitus, John S. Ramsdell, Harold G. Marshall, Nora J. Deamer, S. Craig Cary, Jason W. Kempton, Steven L. Morton, Parke A. Rublee Jan 2005

Demonstration Of Toxicity To Fish And To Mammalian Cells By Pfiesteria Species: Comparison Of Assay Methods And Strains, Joann M. Burkholder, Andrew S. Gordon, Peter D. Moeller, J. Mac Law, Kathryn J. Coyne, Alan J. Lewitus, John S. Ramsdell, Harold G. Marshall, Nora J. Deamer, S. Craig Cary, Jason W. Kempton, Steven L. Morton, Parke A. Rublee

Biological Sciences Faculty Publications

Toxicity and its detection in the dinoflagellate fish predators Pfiesteria piscicida and Pfiesteria shumwayae depend on the strain and the use of reliable assays. Two assays, standardized fish bioassays (SFBs) with juvenile fish and fish microassays (FMAs) with larval fish, were compared for their utility to detect toxic Pfiesteria. The comparison included strains with confirmed toxicity, negative controls (noninducible Pfiesteria strains and a related nontoxic cryptoperidiniopsoid dinoflagellate), and P. shumwayae strain CCMP2089, which previously had been reported as nontoxic. SFBs, standardized by using toxic Pfiesteria (coupled with tests confirming Pfiesteria toxin) and conditions conducive to toxicity expression, reliably detected …

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Vertebrate Gld2 Poly(A) Polymerases In The Germline And The Brain, Labib Rouhana, Liaoteng Wang, Natascha Buter, Jae Eun Kwak, Craig A. Schiltz, Tania Gonzalez, Ann E. Kelley, Charles F. Landry, Marvin Wickens Jan 2005

Vertebrate Gld2 Poly(A) Polymerases In The Germline And The Brain, Labib Rouhana, Liaoteng Wang, Natascha Buter, Jae Eun Kwak, Craig A. Schiltz, Tania Gonzalez, Ann E. Kelley, Charles F. Landry, Marvin Wickens

Biological Sciences Faculty Publications

Cytoplasmic polyadenylation is important in the control of mRNA stability and translation, and for early animal development and synaptic plasticity. Here, we focus on vertebrate poly(A) polymerases that are members of the recently described GLD2 family. We identify and characterize two closely related GLD2 proteins in Xenopus oocytes, and show that they possess PAP activity in vivo and in vitro and that they bind known polyadenylation factors and mRNAs known to receive poly(A) during development. We propose that at least two distinct polyadenylation complexes exist in Xenopus oocytes, one of which contains GLD2; the other, maskin and Pumilio. GLD2 protein …

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Mechanical Properties Of The Integument Of The Common Gartersnake, Thamnophis Sirtalis (Serpentes: Colubridae), Gabriel Rivera, Alan H. Savitzky, Jeffrey A. Hinkley Jan 2005

Mechanical Properties Of The Integument Of The Common Gartersnake, Thamnophis Sirtalis (Serpentes: Colubridae), Gabriel Rivera, Alan H. Savitzky, Jeffrey A. Hinkley

Biological Sciences Faculty Publications

The evolution of the ophidian feeding mechanism has involved substantial morphological restructuring associated with the ability to ingest relatively large prey. Previous studies examining the morphological consequences of macrophagy have concentrated on modifications of the skull and cephalic musculature. Although it is evident that macrophagy requires highly compliant skin, the mechanical properties of the ophidian integument have received limited attention, particularly in the context of feeding. We examined mechanical properties of skin along the body axis in Thamnophis sirtalis (Colubridae). Data were collected from tensile tests and were analyzed using a multivariate analysis of variance (MANOVA) and post-hoc multiple comparison …

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3,4-Methylenedioxymethamphetamine Activates Nuclear Factor- Κb, Increases Intracellular Calcium, And Modulates Gene Transcription In Rat Heart Cells, David A. Tiangco, Frank A. Lattanzio Jr., Christopher J. Osgood, Stephen J. Beebe, Julie A. Kerry, Barbara Y. Hargrave Jan 2005

3,4-Methylenedioxymethamphetamine Activates Nuclear Factor- Κb, Increases Intracellular Calcium, And Modulates Gene Transcription In Rat Heart Cells, David A. Tiangco, Frank A. Lattanzio Jr., Christopher J. Osgood, Stephen J. Beebe, Julie A. Kerry, Barbara Y. Hargrave

Biological Sciences Faculty Publications

3,4-Methylenedioxymethamphetamine (MDMA) is an illicit psychoactive drug that has gained immense popularity among teenagers and young adults. The cardiovascular toxicological consequences of abusing this compound have not been fully characterized. The present study utilized a transient transfection/dual luciferase genetic reporter assay, fluorescence confocal microscopy, and gene expression macroarray technology to determine nuclear factor-κB (NF-κB) activity, intracellular calcium balance, mitochondrial depolarization, and gene transcription profiles, respectively, in cultured rat striated cardiac myocytes (H9c2) exposed to MDMA. At concentrations of 1×10−3 M and 1×10−2 M, MDMA significantly enhanced NF-κB reporter activity compared with 0 M (medium only) control. This …

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A Defensin-Like Gene Expressed In The Black-Legged Tick, Ixodes Scapularis (Acari: Ixodidae), Wayne L. Hynes, S. M. Ceraul, S. M. Todd, K. C. Seguin, Daniel E. Sonenshine Jan 2005

A Defensin-Like Gene Expressed In The Black-Legged Tick, Ixodes Scapularis (Acari: Ixodidae), Wayne L. Hynes, S. M. Ceraul, S. M. Todd, K. C. Seguin, Daniel E. Sonenshine

Biological Sciences Faculty Publications

The black-legged tick Ixodes scapularis linnaeus (Acari: Ixodidae) is an important vector of microbial pathogens. Knowledge of the tick's innate immune response, particularly defensin and other antimicrobial peptides, is important for understanding how microbes survive in this tick. A defensin gene (slnA) from I. scapularis was obtained by reverse transcription-polymerase chain reaction (RT-PCR) using mRNA extracted from tissues of female ticks. RT-PCR indicated the gene was expressed in the midgut, haemocytes, and fat-body, although no evidence of a peptide was found. Sequencing a cloned cDNA fragment revealed a 225 bp open reading frame encoding a 74 amino acid pre-prodefensin, including …

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The Architecture Of A Proteomic Network In The Yeast, Emad Ramadan, Christopher Osgood, Alex Pothern Jan 2005

The Architecture Of A Proteomic Network In The Yeast, Emad Ramadan, Christopher Osgood, Alex Pothern

Biological Sciences Faculty Publications

We describe an approach to clustering the yeast protein-protein inter-action network in order to identify functional modules, groups of proteins forming multi-protein complexes accomplishing various functions in the cell. We have developed a clustering method that accounts for the small-world nature of the network. The algorithm makes use of the concept of k-cores in a graph, and employs recursive spectral clustering to compute the functional modules. The computed clusters are annotated using their protein memberships into known multi-protein complexes in the yeast. We also dissect the protein interaction network into a global subnetwork of hub proteins (connected to several clusters), …

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Comparison Of Phytoplankton And Autotrophic Picoplankton Populations Over A 24-Hour Period From A Pond's Surface And Subsurface Waters, Harold G. Marshall, Lubomira Burchardt, Elżbieta Wilk-Woźniak Jan 2005

Comparison Of Phytoplankton And Autotrophic Picoplankton Populations Over A 24-Hour Period From A Pond's Surface And Subsurface Waters, Harold G. Marshall, Lubomira Burchardt, Elżbieta Wilk-Woźniak

Biological Sciences Faculty Publications

Phytoplankton abundance and composition relationships within the surface layer changed over short time periods (4-6 hours) in comparison with more constant associations at 2 cm below the surface. Both strata had a diverse algal flora (>50 taxa), but no distinct neuston assemblage characterized the surface layer algal composition over the 24-hour study. The similarity between the two strata indicated the floral composition of the surface layer came from the water column algae below the surface. Chlorophytes, diatoms, cyanobacteria, and cryptophytes represented the most abundant algal categories for both strata with a total mean phytoplankton abundance of 3,566 cells ml …

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Soil Biota Facilitate Exotic Acer Invasions In Europe And North America, Kurt O. Reinhart, Ragan M. Callaway Dec 2004

Soil Biota Facilitate Exotic Acer Invasions In Europe And North America, Kurt O. Reinhart, Ragan M. Callaway

Biological Sciences Faculty Publications

The primary hypothesis for successful exotic plant invasions is that the invaders have escaped the specialist consumers that control them (Enemy Release Hypothesis). However, few studies have rigorously tested this assertion with biogeographical experiments or considered the effects of soil organisms. We tested the Enemy Release Hypothesis and the enhanced role of mutualisms by comparing density patterns of the North American Acer negundo and European A. platanoides trees in their native and nonnative ranges. Invaders that have escaped their natural enemies are predicted to attain greater densities in nonnative than native ranges. To determine whether interactions with soil biota could …

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Loss Of Enemy Resistance Among Introduced Populations Of St. John's Wort (Hypericum Perforatum), John L. Maron, Montserrat Vilà, John Arnason Dec 2004

Loss Of Enemy Resistance Among Introduced Populations Of St. John's Wort (Hypericum Perforatum), John L. Maron, Montserrat Vilà, John Arnason

Biological Sciences Faculty Publications

The Evolution of Increased Competitive Ability (EICA) hypothesis predicts that introduced plants should lose enemy resistance and in turn evolve increased size or fecundity. We tested the first prediction of this hypothesis by growing introduced North American and native European genotypes of St. John's Wort (Hypericum perforatum) in common gardens in the state of Washington, USA, and in Girona, Spain. In both gardens we measured levels of hypericin and pseudohypericin (and in Washington, hypericide)— compounds known to be toxic to generalist pathogens and herbivores. In a third common garden, in Spain, we experimentally manipulated native pathogen pressure (by …

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Reconstitution Of Copii Vesicle Fusion To Generate A Pre-Golgi Intermediate Compartment, Dalu Xu, Jesse C. Hay Nov 2004

Reconstitution Of Copii Vesicle Fusion To Generate A Pre-Golgi Intermediate Compartment, Dalu Xu, Jesse C. Hay

Biological Sciences Faculty Publications

What is the first membrane fusion step in the secretory pathway? In mammals, transport vesicles coated with coat complex (COP) II deliver secretary cargo to vesicular tubular clusters (VTCs) that ferry cargo from endoplasmic reticulum exit sites to the Golgi stack. However, the precise origin of VTCs and the membrane fusion step(s) involved have remained experimentally intractable. Here, we document in vitro direct tethering and SNARE-dependent fusion of endoplasmic reticulum-derived COPII transport vesicles to form larger cargo containers. The assembly did not require detectable Golgi membranes, preexisting VTCs, or CON function. Therefore, COPII vesicles appear to contain all of the …

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Evaluating Forensic Dna Evidence: Essential Elements Of A Competent Defense Review, Dan E. Krane Nov 2004

Evaluating Forensic Dna Evidence: Essential Elements Of A Competent Defense Review, Dan E. Krane

Biological Sciences Faculty Publications

No abstract provided.

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The Effects Of Postfire Salvage Logging On Aquatic Ecosystems In The American West, J. R. Karr, Jj Rhodes, Gw Minshall, F. Richard Hauer, R. L. Beschta, C. A. Frissell, D. A. Perry Nov 2004

The Effects Of Postfire Salvage Logging On Aquatic Ecosystems In The American West, J. R. Karr, Jj Rhodes, Gw Minshall, F. Richard Hauer, R. L. Beschta, C. A. Frissell, D. A. Perry

Biological Sciences Faculty Publications

Recent changes in the forest policies, regulations, and laws affecting public lands encourage postfire salvage logging, an activity that all too often delays or prevents recovery. In contrast, the 10 recommendations proposed here can improve the condition of watersheds and aquatic ecosystems.

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Evaluating Forensic Dna Evidence, Dan E. Krane Oct 2004

Evaluating Forensic Dna Evidence, Dan E. Krane

Biological Sciences Faculty Publications

No abstract provided.

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Forensic Dna Evidence: Collection, Mixtures, And Degradation, Dan E. Krane Oct 2004

Forensic Dna Evidence: Collection, Mixtures, And Degradation, Dan E. Krane

Biological Sciences Faculty Publications

No abstract provided.

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Facultative Altitudinal Movements By Mountain White-Crowned Sparrows (Zonotrichia Leucophrys Oriantha) In The Sierra Nevada, Thomas P. Hahn, Keith W. Sockman, Creagh W. Breuner, Martin L. Morton Oct 2004

Facultative Altitudinal Movements By Mountain White-Crowned Sparrows (Zonotrichia Leucophrys Oriantha) In The Sierra Nevada, Thomas P. Hahn, Keith W. Sockman, Creagh W. Breuner, Martin L. Morton

Biological Sciences Faculty Publications

Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha) winter in Mexico and often arrive in the vicinity of their breeding grounds in the Sierra Nevada well before nesting is possible. Arrival at Tioga Pass, Califomia (elevation 3,030 m), usually occurs in early May, but residual winter snow and adverse weather can delay nesting for weeks. We used radiotelemetry to determine whether prebreeding Mountain White-crowned Sparrows engaged in weather-related altitudinal movements during the waiting period between the end of spring migration and onset of breeding during 1995-2001, with a range of residual winter snowpacks. Interannual variation in arrival date and onset …

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The Signal Peptide Of The Junín Arenavirus Envelope Glycoprotein Is Myristoylated And Forms An Essential Subunit Of The Mature G1-G2 Complex, Joanne York, Victor Romanowski, Min Lu, Jack H. Nunberg Oct 2004

The Signal Peptide Of The Junín Arenavirus Envelope Glycoprotein Is Myristoylated And Forms An Essential Subunit Of The Mature G1-G2 Complex, Joanne York, Victor Romanowski, Min Lu, Jack H. Nunberg

Biological Sciences Faculty Publications

Arenaviruses comprise a diverse family of rodent-borne viruses that are responsible for recurring and emerging outbreaks of viral hemorrhagic fevers worldwide. The Junin virus, a member of the New World arenaviruses, is endemic to the pampas grasslands of Argentina and is the etiologic agent of Argentine hemorrhagic fever. In this study, we have analyzed the assembly and function of the Junin virus envelope glycoproteins. The mature envelope glycoprotein complex is proteolytically processed from the GP-C precursor polypeptide and consists of three noncovalently associated subunits, G1, G2, and a stable 58-amino-acid signal peptide. This tripartite organization is found both on virions …

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Novel Weapons: Invasive Success And The Evolution Of Increased Competitive Ability, Ragan M. Callaway, Wendy M. Ridenour Oct 2004

Novel Weapons: Invasive Success And The Evolution Of Increased Competitive Ability, Ragan M. Callaway, Wendy M. Ridenour

Biological Sciences Faculty Publications

When introduced to new habitats by humans, some plant species become much more dominant. This is primarily attributed to escape from specialist consumers. Release from these specialist enemies is also thought by some to lead to the evolution of increased competitive ability, driven by a decrease in the plant's resource allocation to consumer defense and an increase in allocation to size or fecundity. Here, we discuss a new theory for invasive success – the “novel weapons hypothesis”. We propose that some invaders transform because they possess novel biochemical weapons that function as unusually powerful allelopathic agents, or as mediators of …

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Determining Rates Of Change And Evaluating Group-Level Resiliency Differences In Hyporheic Microbial Communities In Response To Fluvial Heavy-Metal Deposition, Kevin P. Feris, Philip W. Ramsey, Matthias Rillig, Johnnie N. Moore, James E. Gannon, William E. Holben Aug 2004

Determining Rates Of Change And Evaluating Group-Level Resiliency Differences In Hyporheic Microbial Communities In Response To Fluvial Heavy-Metal Deposition, Kevin P. Feris, Philip W. Ramsey, Matthias Rillig, Johnnie N. Moore, James E. Gannon, William E. Holben

Biological Sciences Faculty Publications

Prior field studies by our group have demonstrated a relationship between fluvial deposition of heavy metals and hyporheic-zone microbial community structure. Here, we determined the rates of change in hyporheic microbial communities in response to heavy-metal contamination and assessed group-level differences in resiliency in response to heavy metals. A controlled laboratory study was performed using 20 flowthrough river mesocosms and a repeated-measurement factorial design. A single hyporheic microbial community was exposed to five different levels of an environmentally relevant metal treatment (0, 4, 8, 16, and 30% sterilized contaminated sediments). Community-level responses were monitored at 1, 2, 4, 8, and …

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High Polymorphism In The K-Casein (Csn3) Gene From Wild And Domestic Caprine Species Revealed By Dna Sequencing, Oliver C. Jann, Eva-Maria Prinzenberg, Gordon Luikart, Ana Caroli, Georg Erhardt Jun 2004

High Polymorphism In The K-Casein (Csn3) Gene From Wild And Domestic Caprine Species Revealed By Dna Sequencing, Oliver C. Jann, Eva-Maria Prinzenberg, Gordon Luikart, Ana Caroli, Georg Erhardt

Biological Sciences Faculty Publications

We assessed polymorphisms in exon IV of the k-casein gene (CSN3) in ten different breeds of domestic goat (Capra hircus) from three continents and in three related wild caprine taxa (Capra ibex, Capra sibirica and Capra aegagrus). Thirty-five DNA samples were sequenced within a 558 bp fragment of exon IV. Nine polymorphic sites were identified in domestic goat, including four new polymorphisms. In addition to four previously described polymorphic positions, a total of 13 polymorphisms allowed the identification of 13 DNA variants, corresponding to 10 protein variants. Because of conflicting nomenclature of these variants, we propose …

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Kinetic Isotope Effects In Ras-Catalyzed Gtp Hydrolysis: Evidence For A Loose Transition State, Xinlin Du, Gavin E. Black, Paolo Lecchi, Fred P. Abramson, Stephen R. Sprang Jun 2004

Kinetic Isotope Effects In Ras-Catalyzed Gtp Hydrolysis: Evidence For A Loose Transition State, Xinlin Du, Gavin E. Black, Paolo Lecchi, Fred P. Abramson, Stephen R. Sprang

Biological Sciences Faculty Publications

A remote labeling method has been developed to determine (18)O kinetic isotope effects (KIEs) in Ras-catalyzed GTP hydrolysis. Substrate mixtures consist of (13)C-depleted GTP and [(18)O,(13)C]GTP that contains (18)O at phosphoryl positions of mechanistic interest and (13)C at all carbon positions of the guanosine moiety. Isotope ratios of the nonvolatile substrates and products are measured by using a chemical reaction interface/isotope ratio mass spectrometer. The isotope effects are 1.0012 (0.0026) in the gamma nonbridge oxygens, 1.0194 (0.0025) in the leaving group oxygens (the beta-gamma oxygen and the two beta nonbridge oxygens), and 1.0105 (0.0016) in the two beta nonbridge oxygens. …

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Cancer. A Bull's Eye For Targeted Lung Cancer Therapy, John D. Minna, Adi F. Gazdar, Stephen R. Sprang, Joachim Herz Jun 2004

Cancer. A Bull's Eye For Targeted Lung Cancer Therapy, John D. Minna, Adi F. Gazdar, Stephen R. Sprang, Joachim Herz

Biological Sciences Faculty Publications

No abstract provided.

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Evolution Of Morphological Integration. I. Functional Units Channel Stress-Induced Variation In Shrew Mandibles, Alexander V. Badyaev, Kerry R. Foresman Jun 2004

Evolution Of Morphological Integration. I. Functional Units Channel Stress-Induced Variation In Shrew Mandibles, Alexander V. Badyaev, Kerry R. Foresman

Biological Sciences Faculty Publications

Stress-induced deviations from normal development are often assumed to be random, yet their accumulation and expression can be influenced by patterns of morphological integration within an organism. We studied within-individual developmental variation ( fluctuating asymmetry) in the mandible of four shrew species raised under normal and extreme environments. Patterns of among-individual variation and fluctuating asymmetry were strongly concordant in traits that were involved in the attachment of the same muscles (i.e., functionally integrated traits), and fluctuating asymmetry was closely integrated among these traits, implying direct developmental interactions among traits involved in the same function. Stress-induced variation was largely confined to …

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Uncoupling Conformational Change From Gtp Hydrolysis In A Heterotrimeric G Protein Alpha-Subunit, Celestine J. Thomas, Xinlin Du, Pilong Li, Ying Wang, Elliott M. Ross, Stephen R. Sprang May 2004

Uncoupling Conformational Change From Gtp Hydrolysis In A Heterotrimeric G Protein Alpha-Subunit, Celestine J. Thomas, Xinlin Du, Pilong Li, Ying Wang, Elliott M. Ross, Stephen R. Sprang

Biological Sciences Faculty Publications

Heterotrimeric G protein alpha (G alpha) subunits possess intrinsic GTPase activity that leads to functional deactivation with a rate constant of approximately 2 min(-1) at 30 degrees C. GTP hydrolysis causes conformational changes in three regions of G alpha, including Switch I and Switch II. Mutation of G202-->A in Switch II of G alpha(i1) accelerates the rates of both GTP hydrolysis and conformational change, which is measured by the loss of fluorescence from Trp-211 in Switch II. Mutation of K180-->P in Switch I increases the rate of conformational change but decreases the GTPase rate, which causes transient but …

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