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Full-Text Articles in Biology

Physical Interaction Between Vivid And White Collar Complex Regulates Photoadaptation In Neurospora, Chen-Hui H. Chen, Bradley S. Demay, Amy S. Gladfelter, Jay Dunlap, Jennifer J. Loros Sep 2010

Physical Interaction Between Vivid And White Collar Complex Regulates Photoadaptation In Neurospora, Chen-Hui H. Chen, Bradley S. Demay, Amy S. Gladfelter, Jay Dunlap, Jennifer J. Loros

Dartmouth Scholarship

Photoadaptation, the ability to attenuate a light response on prolonged light exposure while remaining sensitive to escalating changes in light intensity, is essential for organisms to decipher time information appropriately, yet the underlying molecular mechanisms are poorly understood. In Neurospora crassa, VIVID (VVD), a small LOV domain containing blue-light photoreceptor protein, affects photoadaptation for most if not all light-responsive genes. We report that there is a physical interaction between VVD and the white collar complex (WCC), the primary blue-light photoreceptor and the transcription factor complex that initiates light-regulated transcriptional responses in Neurospora. Using two previously characterized VVD mutants, we show …


Stoichiometric Controls Of Mercury Dilution By Growth, Roxanne Karimi, Celia Y. Chen, Paul C. Pickhardt, Nicholas S. Fisher, Carol L. Folt May 2007

Stoichiometric Controls Of Mercury Dilution By Growth, Roxanne Karimi, Celia Y. Chen, Paul C. Pickhardt, Nicholas S. Fisher, Carol L. Folt

Dartmouth Scholarship

Rapid growth could significantly reduce methylmercury (MeHg) concentrations in aquatic organisms by causing a greater than proportional gain in biomass relative to MeHg (somatic growth dilution). We hypothesized that rapid growth from the consumption of high-quality algae, defined by algal nutrient stoichiometry, reduces MeHg concentrations in zooplankton, a major source of MeHg for lake fish. Using a MeHg radiotracer, we measured changes in MeHg concentrations, growth and ingestion rates in juvenile Daphnia pulex fed either high (C:P = 139) or low-quality (C:P = 1317) algae (Ankistrodesmus falcatus) for 5 d. We estimated Daphnia steady-state MeHg concentrations, using a …


A Role For The Light-Dependent Phosphorylation Of Visual Arrestin, Paul G. Alloway, Patrick J. Dolph May 1999

A Role For The Light-Dependent Phosphorylation Of Visual Arrestin, Paul G. Alloway, Patrick J. Dolph

Dartmouth Scholarship

Arrestins are regulatory proteins that participate in the termination of G protein-mediated signal transduction. The major arrestin in the Drosophila visual system, Arrestin 2 (Arr2), is phosphorylated in a light-dependent manner by a Ca2+/calmodulin-dependent protein kinase and has been shown to be essential for the termination of the visual signaling cascade in vivo. Here, we report the isolation of nine alleles of the Drosophila photoreceptor cell-specific arr2 gene. Flies carrying each of these alleles underwent light-dependent retinal degeneration and displayed electrophysiological defects typical of previously identified arrestin mutants, including an allele encoding a protein that lacks the major Ca2+/calmodulin-dependent protein …


Ets-Core Binding Factor: A Common Composite Motif In Antigen Receptor Gene Enhancers, Batu Erman, Marta Cortes, Barbara S. Nikolajczyk, Nancy A. Speck, Ranjan Sen Dec 1997

Ets-Core Binding Factor: A Common Composite Motif In Antigen Receptor Gene Enhancers, Batu Erman, Marta Cortes, Barbara S. Nikolajczyk, Nancy A. Speck, Ranjan Sen

Dartmouth Scholarship

A tripartite domain of the murine immunoglobulin μ heavy-chain enhancer contains the μA and μB elements that bind ETS proteins and the μE3 element that binds leucine zipper-containing basic helix-loop-helix (bHLH-zip) factors. Analysis of the corresponding region of the human μ enhancer revealed high conservation of the μA and μB motifs but a striking absence of the μE3 element. Instead of bHLH-zip proteins, we found that the human enhancer bound core binding factor (CBF) between the μA and μB elements; CBF binding was shown to be a common feature of both murine and human enhancers. Furthermore, mutant enhancers that bound …


The Primary Structure Of A Fungal Chitin Deacetylase Reveals The Function For Two Bacterial Gene Products., Dimitris Kafetzopoulos, George Thireos, John N. Vournakis, Vassilis Bouriotis Sep 1993

The Primary Structure Of A Fungal Chitin Deacetylase Reveals The Function For Two Bacterial Gene Products., Dimitris Kafetzopoulos, George Thireos, John N. Vournakis, Vassilis Bouriotis

Dartmouth Scholarship

Chitin deacetylase (EC 3.5.1.41) hydrolyzes the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin. A cDNA to the Mucor rouxii mRNA encoding chitin deacetylase was isolated, characterized, and sequenced. Protein sequence comparisons revealed significant similarities of the fungal chitin deacetylase to rhizobial nodB proteins and to an uncharacterized protein encoded by a Bacillus stearothermophilus open reading frame. These data suggest the functional homology of these evolutionarily distant proteins. NodB is a chitooligosaccharide deacetylase essential for the biosynthesis of the bacterial nodulation signals, termed Nod factors. The observed similarity of chitin deacetylase to the B. stearothermophilus gene product suggests that this gene …