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Full-Text Articles in Life Sciences
Pseudoreplication Revisited, Robert A. Heffner, Mark J. Butler Iv, Colleen Keelan Reilly
Pseudoreplication Revisited, Robert A. Heffner, Mark J. Butler Iv, Colleen Keelan Reilly
Biological Sciences Faculty Publications
No abstract provided.
Structure Of The Gdp-Pi Complex Of Gly203→Ala G(Iα1): A Mimic Of The Ternary Product Complex Of Galpha-Catalyzed Gtp Hydrolysis, Albert M. Berghuis, Ethan Lee, André S. Raw, Alfred G. Gilman, Stephen R. Sprang
Structure Of The Gdp-Pi Complex Of Gly203→Ala G(Iα1): A Mimic Of The Ternary Product Complex Of Galpha-Catalyzed Gtp Hydrolysis, Albert M. Berghuis, Ethan Lee, André S. Raw, Alfred G. Gilman, Stephen R. Sprang
Biological Sciences Faculty Publications
Background: G proteins play a vital role in transmembrane signalling events. In their inactive form G proteins exist as heterotrimers consisting of an α subunit, complexed with GDP and a dimer of βγ subunits. Upon stimulation by receptors, G protein α subunits exchange GDP for GTP and dissociate from βγ. Thus activated, α subunits stimulate or inhibit downstream effectors. The duration of the activated state corresponds to the single turnover rate of GTP hydrolysis, which is typically in the range of seconds. In G(iα1), the Gly203→Ala mutation reduces the affinity of the substrate for Mg2+, inhibits a key …
Structures Of The Extracellular Domain Of The Type I Tumor Necrosis Factor Receptor, James H. Naismith, Tracey Q. Devine, Tadahiko Kohno, Stephen R. Sprang
Structures Of The Extracellular Domain Of The Type I Tumor Necrosis Factor Receptor, James H. Naismith, Tracey Q. Devine, Tadahiko Kohno, Stephen R. Sprang
Biological Sciences Faculty Publications
Background: Tumor necrosis factor (TNF) is a powerful cytokine that is involved in immune and pro-inflammatory responses. Two TNF receptors that belong to the cysteine-rich low affinity nerve growth factor receptor family (TNF-R1 and TNF-R2) are the sole mediators of TNF signalling. Signalling is thought to occur when a trimer of TNF binds to the extracellular domains of two or three receptor molecules, which permits aggregation and activation of the cytoplasmic domains. The complex is then internalized within an endocytic vesicle, whereupon it dissociates at low pH. Structure of the soluble extracellular domain of the receptor (sTNF-R1) both in the …
Directed Insertion Of A Selectable Marker Into A Circular Plasmid Of Borrelia Burgdorferi, Patricia Rosa, D. Scott Samuels, Daniel Hogan, Brian Stevenson, Sherwood Casjens, Kit Tilly
Directed Insertion Of A Selectable Marker Into A Circular Plasmid Of Borrelia Burgdorferi, Patricia Rosa, D. Scott Samuels, Daniel Hogan, Brian Stevenson, Sherwood Casjens, Kit Tilly
Biological Sciences Faculty Publications
Studies of the biology of Borrelia burgdorferi and the pathogenesis of Lyme disease are severely limited by the current lack of genetic tools. As an initial step toward facile genetic manipulation of this pathogenic spirochete, we have investigated gene inactivation by allelic exchange using a mutated borrelial gyrB gene that confers resistance to the antibiotic coumermycin A(1) as a selectable marker. We have transformed B. burgdorferi by electroporation with a linear fragment of DNA in which this selectable marker was flanked by sequences from a native borrelial 26-kb circular plasmid. We have identified coumermycin A(1)-resistant transformants in which gyrB had …
Competition And Facilitation: Contrasting Effects Of Artemisia Tridentata On Desert Vs Montane Pines, Ragan M. Callaway, Eh Delucia, Darrin Moore, R Nowak, W. H. Schlesinger, Brenda J. Moor
Competition And Facilitation: Contrasting Effects Of Artemisia Tridentata On Desert Vs Montane Pines, Ragan M. Callaway, Eh Delucia, Darrin Moore, R Nowak, W. H. Schlesinger, Brenda J. Moor
Biological Sciences Faculty Publications
Circumstantial evidence suggests that Artemisia tridentata may out-compete Pinus ponderosa and P. jefferyi for water at ecotones between shrub steppe and montane forest vegetation in the Great Basin. Other studies indicate that within the shrub steppe Artemisia may act as a nurse plant for a third species of pine, P. monophylla. We used field experiments to study these contrasting effects of Artemisia on P, ponderosa and P. monophylla within the contest of the distributional patterns in western Nevada of all three species on andesite, and on sites where hydrothermal activity has altered the andesite. At intermediate elevations in the Great …
A Protocol For Ecosystem Management, Jack A. Stanford, G. C. Poole
A Protocol For Ecosystem Management, Jack A. Stanford, G. C. Poole
Biological Sciences Faculty Publications
No abstract provided.
Abiotic Stress And The Relative Importance Of Interference And Facilitation In Montane Bunchgrass Communities In Western Montana, John T. Greenlee, Ragan M. Callaway
Abiotic Stress And The Relative Importance Of Interference And Facilitation In Montane Bunchgrass Communities In Western Montana, John T. Greenlee, Ragan M. Callaway
Biological Sciences Faculty Publications
No abstract provided.
Evidence For Acquisition In Nature Of A Chromosomal 2,4-Dichlorophenoxyacetic Acid/(Alpha)-Ketoglutarate Dioxygenase Gene By Different Burkholderia Spp., V. Grace Matheson, Larry J. Forney, Yuichi Suwa, Cindy H. Nakahatsu, Alan J. Sexstone, William E. Holben
Evidence For Acquisition In Nature Of A Chromosomal 2,4-Dichlorophenoxyacetic Acid/(Alpha)-Ketoglutarate Dioxygenase Gene By Different Burkholderia Spp., V. Grace Matheson, Larry J. Forney, Yuichi Suwa, Cindy H. Nakahatsu, Alan J. Sexstone, William E. Holben
Biological Sciences Faculty Publications
We characterized the gene required to initiate the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) by the soil bacterium Burkholderia sp. strain TFD6, which hybridized to the tfdA gene of the canonical 2,4-D catabolic plasmid pJP4 under low-stringency conditions. Cleavage of the ether bond of 2,4-D by cell extracts of TFD6 proceeded by an (alpha)-ketoglutarate-dependent reaction,characteristic of TfdA (F. Fukumori and R. P. Hausinger, J. Bacteriol. 175:2083-2086, 1993). The TFD6 tfdA gene was identified in a recombinant plasmid which complemented a tfdA transposon mutant of TFD6 created by chromosomal insertion of Tn5. The plasmid also expressed TfdA activity in Escherichia coli …
Characterization Of A Chromosomally Encoded 2,4-Dichlorophenoxyacetic Acid/A-Ketoglutarate Dioxygenase From Burkholderia Sp. Strain Rasc, Yuichi Suwa, Alice D. Wright, Fumitasu Fukimori, Kathy A. Nummy, Robert P. Hausinger, William E. Holben, Larry J. Forney
Characterization Of A Chromosomally Encoded 2,4-Dichlorophenoxyacetic Acid/A-Ketoglutarate Dioxygenase From Burkholderia Sp. Strain Rasc, Yuichi Suwa, Alice D. Wright, Fumitasu Fukimori, Kathy A. Nummy, Robert P. Hausinger, William E. Holben, Larry J. Forney
Biological Sciences Faculty Publications
The findings of previous studies indicate that the genes required for metabolism of the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) are typically encoded on broad-host-range plasmids. However, characterization of plasmid-cured strains of Burkholderia sp. strain RASC, as well as mutants obtained by transposon mutagenesis, suggested that the 2,4-D catabolic genes were located on the chromosome of this strain. Mutants of Burkholderia strain RASC unable to degrade 2,4-D (2,4-D- strains) were obtained by insertional inactivation with Tn5. One such mutant (d1) was shown to have Tn5 inserted in tfdARASC, which encodes 2,4-D/alpha-ketoglutarate dioxygenase. This is the first reported example of a …
Impact Of A Parasitic Plant On The Structure And Dynamics Of Salt Marsh Vegetation, Steven C. Pennings, Ragan M. Callaway
Impact Of A Parasitic Plant On The Structure And Dynamics Of Salt Marsh Vegetation, Steven C. Pennings, Ragan M. Callaway
Biological Sciences Faculty Publications
We investigated the effect of a native parasitic plant, Cuscuta salina, on the structure and dynamics of the plant community in a California salt marsh. Cuscuta was common in the middle marsh zones. The abundance of Cuscuta was positively correlated with the abundance of Limonium californicum at two sampling scales (0.25— and ≈\approx40—m2 quadrats). Sampling at the scale of individual plants indicated that the dominant plant in the marsh, Salicornia virginica, was preferred by Cuscuta as a host over Arthrocnemum subterminale, Limonium californicum, and Frankenia salina. This result was confirmed with host—choice experiments in the field. Based on spatial …
Temperature-Driven Variation In Substrate Oxygenation And The Balance Of Competition And Facilitation, Ragan M. Callaway, Leah King
Temperature-Driven Variation In Substrate Oxygenation And The Balance Of Competition And Facilitation, Ragan M. Callaway, Leah King
Biological Sciences Faculty Publications
Emergent wetland plants often alleviate the effects of anaerobic soils on root respiration by passively transporting oxygen belowground through continuous air spaces (aerenchyma) in leaves and roots. Oxygen leaked from the roots into the rhizosphere may oxidize minerals in the soil or become available to other plants. Some spatial patterns in marsh plant communities suggest interspecific facilitative interactions, but there is little experimental evidence for interplant facilitation via soil oxygenation. We investigated the capability of the widespread, highly aerenchymous wetland plant, Typa latifolia, to aerate sediments and affect the growth of two non—aerenchymous neighbors, Salix exigua and Myosotis laxa, both …
Analysis Of Linear Plasmid Dimers In Borrelia Burgdorferi Sensu Lato Isolates: Implications Concerning The Potential Mechanism Of Linear Plasmid Replication, Richard T. Marconi, Sherwood Casjens, Ulrike G. Munderloh, D. Scott Samuels
Analysis Of Linear Plasmid Dimers In Borrelia Burgdorferi Sensu Lato Isolates: Implications Concerning The Potential Mechanism Of Linear Plasmid Replication, Richard T. Marconi, Sherwood Casjens, Ulrike G. Munderloh, D. Scott Samuels
Biological Sciences Faculty Publications
The Borrelia genome is composed of a linear chromosome and a number of variable circular and linear plasmids. Atypically large linear plasmids of 92 to 105 kb have been identified in several Borrelia burgdorferi sensu lato isolates and characterized. These plasmids carry the p27 and ospAB genes, which in other isolates reside on a 50-kb plasmid. Here we demonstrate that these plasmids are dimers of the 50-kb ospAB plasmid (pAB50). The 94-kb plasmid from isolate VS116, pVS94, was an exception and did not hybridize with any plasmid gene probes. When this plasmid was used as a probe, homologous sequences in …
Top-Down Cascade From A Bitrophic Predator In An Old-Field Community, Matthew D. Moran, Thomas P. Rooney, L. E. Hurd
Top-Down Cascade From A Bitrophic Predator In An Old-Field Community, Matthew D. Moran, Thomas P. Rooney, L. E. Hurd
Biological Sciences Faculty Publications
We tested the hypothesis that a bitrophic (third and fourth level) arthropod predator can exert a cascading, top-down influence on other arthropods and plants in an early successional old field. First-stadium mantids, Tenodera sinensis, were added to replicated open-field plots in numbers corresponding to naturally occurring egg hatch density and allowed to remain for ≈ 2 mo. Sticky-trap dispersal barriers around both control and mantid-addition plots allowed us to monitor emigration of arthropods continuously during the experiment. Biomass of herbivores, carnivores, and plants, and abundances of arthropod taxa within plots were determined at the beginning, middle, and end of …
Variation In Leaf Structure And Function In Quercus Douglasii Trees Differing In Root Architecture And Drought History, Ragan M. Callaway, Bruce E. Mahall
Variation In Leaf Structure And Function In Quercus Douglasii Trees Differing In Root Architecture And Drought History, Ragan M. Callaway, Bruce E. Mahall
Biological Sciences Faculty Publications
Seasonal changes in leaf specific mass, nitrogen, chlorophyll, and photosynthetic properties were measured for two groups of spatially intermixed Quercus douglasii trees with different drought histories and apparently different root architectures. One group, referred to as ''high-psi(pd) trees, included trees with low amounts of fine root biomass in the upper 50 cm of soil and high predawn xylem pressure potentials (psi(pd)) during summer drought. These two characteristics indicate that trees in this group have deep roots, which may reach the water table. The second group, referred to as ''low-psi(pd) trees, had three to five times higher fine root biomass in …
Seeing Double: Crystal Structures Of The Type I Tnf Receptor, James H. Naismith, Barbara J. Brandhuber, Tracey Q. Devine, Stephen R. Sprang
Seeing Double: Crystal Structures Of The Type I Tnf Receptor, James H. Naismith, Barbara J. Brandhuber, Tracey Q. Devine, Stephen R. Sprang
Biological Sciences Faculty Publications
The crystal structure of the extracellular domain of the type I tumor necrosis factor receptor (sTNF-R1) has been determined to 2.25 Å at pH 7.5. We have also solved the structure of sTNF-R1 at pH 3.7. sTNF-R1 is an elongated molecule consisting of a linear combination of four cysteine-rich motifs. Interestingly, the crystal structure reveals two distinct dimers of the receptor. One dimer is formed by a parallel arrangement of receptors, the other by an antiparallel arrangement of receptors. In the parallel arrangement of the receptors, the tumor necrosis factor (TNF) binding face of the receptor is completely exposed to …
Toxin Producing Phytoplankton In Chesapeake Bay, Harold G. Marshall
Toxin Producing Phytoplankton In Chesapeake Bay, Harold G. Marshall
Biological Sciences Faculty Publications
Three diatoms and nine dinoflagellates, known to be associated with toxin production, have been identified within Chesapeake Bay. Over the past several decades this number has increased to its present level so that they now represent approximately 1.7% the total number of phytoplankton species reported for the Bay.
Scaling Of Muscle Composition, Wing Morphology, And Intermittent Flight Behavior In Woodpeckers, Bret W. Tobalske
Scaling Of Muscle Composition, Wing Morphology, And Intermittent Flight Behavior In Woodpeckers, Bret W. Tobalske
Biological Sciences Faculty Publications
Existing theory and empirical evidence suggest that body size should have a profound influence upon the composition of flight muscles and the performance of intermittent flight in birds. I examine the relationships between functional morphology and intermittent flight behavior within a closely-related group of birds using six species of woodpeckers (Picidae): Downy Woodpecker (Picoides pubescens, 27.2 g), Red-naped Sapsucker (Sphyrapicus nuchalis, 47.4 g), Hairy Woodpecker (P. villosus, 70.5 g), Lewis' Woodpecker (Melanerpes lewis, 106.6 g), Northern Flicker (Colaptes auratus, 148.1 g), and Pileated Woodpecker (Dryocopus pileatus, 262.5 g). In woodpeckers with a body mass less than 100 g, the pectoralis …
Effects Of Regional Origin And Genotype On Intraspecific Root Communication In The Desert Shrub Ambrosia Dumosa (Asteraceae), Bruce E. Mahall, Ragan M. Callaway
Effects Of Regional Origin And Genotype On Intraspecific Root Communication In The Desert Shrub Ambrosia Dumosa (Asteraceae), Bruce E. Mahall, Ragan M. Callaway
Biological Sciences Faculty Publications
Previous work has shown that the contact inhibition that occurs among roots of Ambrosia dumosa shrubs has a self/nonself recognition capability. In the current study, we investigated some of the geographic and genotypic dimensions of this recognition capability by using root observation chambers to observe the effects of encounters of individual roots on root elongation rates. We measured such effects in encounters between roots of plants from the same region and compared these to effects in encounters between roots of plants from two different regions. We also measured effects of encounters between roots of plants from the same clones and …