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Full-Text Articles in Life Sciences
Blue-Throated Hummingbird Song: A Pinnacle Of Nonoscine Vocalizations, Millicent S. Ficken, Kathryn M. Rusch, Sandra J. Taylor, Donald R. Powers
Blue-Throated Hummingbird Song: A Pinnacle Of Nonoscine Vocalizations, Millicent S. Ficken, Kathryn M. Rusch, Sandra J. Taylor, Donald R. Powers
Faculty Publications - Department of Biological & Molecular Science
Little is known about the structure and function of hummingbird vocalizations. We studied the vocalizations of Blue-throated Hummingbirds (Lampornis clemenciae) at two sites in southeastern Arizona. Songs were produced by males and females. Male songs consisted of arrays of notes organized in clusters of ‘‘song units.’’ Within sites, all males shared the same song units. Individual differences occurred in some temporal aspects of song, and slight but consistent differences in note structure occurred between the two sites. The organization of units within songs was marked by rigid syntax, and long songs were produced by agglutination of units. Male …
The Holliday Junction In An Inverted Repeat Dna Sequence: Sequence Effects On The Structure Of Four-Way Junctions, Brandt F. Eichman, Jeff Vargason, Blaine H.M. Mooers, P. Shing Ho
The Holliday Junction In An Inverted Repeat Dna Sequence: Sequence Effects On The Structure Of Four-Way Junctions, Brandt F. Eichman, Jeff Vargason, Blaine H.M. Mooers, P. Shing Ho
Faculty Publications - Department of Biological & Molecular Science
Holliday junctions are important structural intermediates in recombination, viral integration, and DNA repair. We present here the single-crystal structure of the inverted repeat sequence d(CCGGTACCGG) as a Holliday junction at the nominal resolution of 2.1 Å. Unlike the previous crystal structures, this DNA junction has B-DNA arms with all standard Watson–Crick base pairs; it therefore represents the intermediate proposed by Holliday as being involved in homologous recombination. The junction is in the stacked-X conformation, with two interconnected duplexes formed by coaxially stacked arms, and is crossed at an angle of 41.4° as a right-handed X. A sequence comparison with previous …
The Extended And Eccentric E-Dna Structure Induced By Cytosine Methylation Or Bromination, Jeff Vargason, Brandt F. Eichman, P. Shing Ho
The Extended And Eccentric E-Dna Structure Induced By Cytosine Methylation Or Bromination, Jeff Vargason, Brandt F. Eichman, P. Shing Ho
Faculty Publications - Department of Biological & Molecular Science
Cytosine methylation or bromination of the DNA sequence d(GGCGCC)2 is shown here to induce a novel extended and eccentric double helix, which we call E-DNA. Like B-DNA, E-DNA has a long helical rise and bases perpendicular to the helix axis. However, the 3′-endo sugar conformation gives the characteristic deep major groove and shallow minor groove of A-DNA. Also, if allowed to crystallize for a period of time longer than that yielding E-DNA, the methylated sequence forms standard A-DNA, suggesting that E-DNA is a kinetically trapped intermediate in the transition to A-DNA. Thus, the structures presented here chart a crystallographic pathway …
B2-Adrenergic Receptor Activates Extracellular Signal-Regulated Kinases (Erks) Via The Small G Protein Rap1 And The Serine/Threonine Kinase B-Raf, John M. Schmitt, Philip J. S. Stork
B2-Adrenergic Receptor Activates Extracellular Signal-Regulated Kinases (Erks) Via The Small G Protein Rap1 And The Serine/Threonine Kinase B-Raf, John M. Schmitt, Philip J. S. Stork
Faculty Publications - Department of Biological & Molecular Science
G protein-coupled receptors can induce cellular proliferation by stimulating the mitogen-activated protein (MAP) kinase cascade. Heterotrimeric G proteins are composed of both a and By subunits that can signal independently to diverse intracellular signaling pathways including those that activate MAP kinases. In this study, we examined the ability of isoproterenol, an agonist of the B2-adrenergic receptor (b2AR), to stimulate extracellular signal-regulated kinases (ERKs). Using HEK293 cells, which express endogenous b2AR, we show that isoproterenol stimulates ERKs via b2AR. This action of isoproterenol requires cAMP-dependent protein kinase and is insensitive to pertussis toxin, suggesting that Gas activation of cAMP-dependent protein kinase …
Cd28 And The Tyrosine Kinase Lck Stimulate Mitogen-Activated Protein Kinase Activity In T Cells Via Inhibition Of The Small G Protein Rap1, Kendall D. Carey, Tara J. Dillon, John M. Schmitt, Allison M. Baird, Amy D. Holdorf, David B. Straus, Andrey S. Shaw, Philip J. S. Stork
Cd28 And The Tyrosine Kinase Lck Stimulate Mitogen-Activated Protein Kinase Activity In T Cells Via Inhibition Of The Small G Protein Rap1, Kendall D. Carey, Tara J. Dillon, John M. Schmitt, Allison M. Baird, Amy D. Holdorf, David B. Straus, Andrey S. Shaw, Philip J. S. Stork
Faculty Publications - Department of Biological & Molecular Science
Proliferation of T cells via activation of the T-cell receptor (TCR) requires concurrent engagement of accessory costimulatory molecules to achieve full activation. The best-studied costimulatory molecule, CD28, achieves these effects, in part, by augmenting signals from the TCR to the mitogen-activated protein (MAP) kinase cascade. We show here that TCR-mediated stimulation of MAP kinase extracellular-signal-regulated kinases (ERKs) is limited by activation of the Ras antagonist Rap1. CD28 increases ERK signaling by blocking Rap1 action. CD28 inhibits Rap1 activation because it selectively stimulates an extrinsic Rap1 GTPase activity. The ability of CD28 to stimulate Rap1 GTPase activity was dependent on the …
Interface Between Titanium Miniplate/Screw And Human Calvaria, Kun Hwang, John M. Schmitt, Jeffrey O. Hollinger
Interface Between Titanium Miniplate/Screw And Human Calvaria, Kun Hwang, John M. Schmitt, Jeffrey O. Hollinger
Faculty Publications - Department of Biological & Molecular Science
This study demonstrates interfacial changes of titanium miniplate/screw with normal calvaria and nonvascularized calvarial bone graft ensued from craniectomy in a 53-year-old female. In 18 months after operation, a right parietal bone containing an L-shaped miniplate with screws, 5mm long and 2mm in external diameter, was harvested, fixed, and embedded in methylmetacrylate. Fifteen micrometer thick sections were made by an EXAKT cutting-grinding system (Exakt Company, Hamburg, Germany), and reviewed under the bright field light microscope. The mean of the bonecontacting surface ratio (BCSR) in six screwed bone was 64.1%; 69.3% in normal bone, and 60.4% in grafted bone. The trabecular …
Does The Aquatic Salamander, Siren Intermedia, Respond To Chemical Cues From Prey?, Aaron M. Sullivan, Paul W. Frese, Alicia Mathis
Does The Aquatic Salamander, Siren Intermedia, Respond To Chemical Cues From Prey?, Aaron M. Sullivan, Paul W. Frese, Alicia Mathis
Faculty Publications - Department of Biological & Molecular Science
No abstract provided.