60 research outputs found
Proteasome Nuclear Import Mediated by Arc3 Can Influence Efficient DNA Damage Repair and Mitosis in Schizosaccharomyces Pombe
Proteasomes must efficiently remove their substrates throughout the cells in a timely manner as many of these proteins can be toxic. This study shows that proteasomes can do so efficiently because they are highly mobile. Furthermore this study uncovers that proteasome mobility requires functional Arc3, a subunit of the Arp2/3 complex
Caveolin regulates endocytosis of the muscle repair protein, dysferlin
Dysferlin and Caveolin-3 are plasma membrane proteins associated wtih muscular dystrophy. Patients with mutations in the CAV3 gene show dysferlin mislocalization in muscle cells
A bridge between worlds: understanding network structure to understand change strategy
A number of scholars are exploring district and site relations in organizational change efforts in the larger policy context of No Child Left Behind. These studies suggest the importance of the central office as a support to the work of reform and offer strategies for building relations between district offices and sites in order to implement and sustain change efforts. What is frequently overlooked in these studies is that organizational change efforts are often socially constructed. Therefore, examining the underlying social networks may provide insight into structures that support or constrain efforts at change. This exploratory case study uses social network analysis and interviews to examine the communication and knowledge network structures of central office and site leaders in an ‘in need of improvement’ district facing sanctions under No Child Left Behind. Findings indicate sparse ties among and between school site and central office administrators, as well as a centralized network structure that may constrain the exchange of complex information and ultimately inhibit efforts at change
Ion channel clustering enhances weak electric field detection by neutrophils: apparent roles of SKF96365-sensitive cation channels and myeloperoxidase trafficking in cellular responses
We have tested Galvanovskis and Sandblom’s prediction that ion channel clustering enhances weak electric field detection by cells as well as how the elicited signals couple to metabolic alterations. Electric field application was timed to coincide with certain known intracellular chemical oscillators (phase-matched conditions). Polarized, but not spherical, neutrophils labeled with anti-K v 1.3, FL-DHP, and anti-TRP1, but not anti-T-type Ca 2+ channels, displayed clusters at the lamellipodium. Resonance energy transfer experiments showed that these channel pairs were in close proximity. Dose-field sensitivity studies of channel blockers suggested that K + and Ca 2+ channels participate in field detection, as judged by enhanced oscillatory NAD(P)H amplitudes. Further studies suggested that K + channel blockers act by reducing the neutrophil’s membrane potential. Mibefradil and SKF93635, which block T-type Ca 2+ channels and SOCs, respectively, affected field detection at appropriate doses. Microfluorometry and high-speed imaging of indo-1-labeled neutrophils was used to examine Ca 2+ signaling. Electric fields enhanced Ca 2+ spike amplitude and triggered formation of a second traveling Ca 2+ wave. Mibefradil blocked Ca 2+ spikes and waves. Although 10 μM SKF96365 mimicked mibefradil, 7 μM SKF96365 specifically inhibited electric field-induced Ca 2+ signals, suggesting that one SKF96365-senstive site is influenced by electric fields. Although cells remained morphologically polarized, ion channel clusters at the lamellipodium and electric field sensitivity were inhibited by methyl-β-cyclodextrin. As a result of phase-matched electric field application in the presence of ion channel clusters, myeloperoxidase (MPO) was found to traffic to the cell surface. As MPO participates in high amplitude metabolic oscillations, this suggests a link between the signaling apparatus and metabolic changes. Furthermore, electric field effects could be blocked by MPO inhibition or removal while certain electric field effects were mimicked by the addition of MPO to untreated cells. Therefore, channel clustering plays an important role in electric field detection and downstream responses of morphologically polarized neutrophils. In addition to providing new mechanistic insights concerning electric field interactions with cells, our work suggests novel methods to remotely manipulate physiological pathways.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46726/1/249_2005_Article_1.pd
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Tree-Rings and the Aging of Trees: A Controversy in 19th Century America
During the late 19th Century there was considerable debate in the United States among members of the legal profession, the general public and even some scientists about the validity of using tree rings to determine tree age. In an earlier boundary dispute case in Maryland (1830) the Honorable Theodorick Bland rejected the use of tree rings to establish the date when a purported witness tree was marked with an identifying blaze. Bland did not believe that there was enough scientific evidence or legal precedent to support this idea. A review of the current scientific literature of the time, however, indicates that most scientists, especially in Europe, accepted that tree rings could be used to determine age. In the United States, however, this idea was debated, particularly in the late 19th Century, in both the popular press and scientific publications. The main argument of opponents such as A. L. Child was that the number of tree rings was often wildly in excess of the known age of the tree. These inconsistencies were likely because of the inexperience of the observer, mistaking earlywood and latewood for separate rings, and the presence of a small number of false rings, sometimes called secondary rings. The great ages reported for the giant sequoias may have also raised doubts among the public. Among scientists, however, the relationship between ring number and tree age and between ring width and climate became widely accepted. Several cases heard in both Federal and State Courts as well as Bernhard E. Fernow’s Age of Trees and Time of Blazing Determined by Annual Rings laid to rest any doubt of the relationship between tree rings and age in temperate forests, i.e. one ring equals one year’s growth, and showed that the date when a witness tree was blazed could be easily determined from a cross-section of the trunk.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring Research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
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