Life Sciences Commons^™

Syd-1, A Presynaptic Protein With Pdz, C2 And Rhogap-Like Domains, Specifies Axon Identity In C. Elegans, Steven Hallam, Alexandr Goncharov, Jason Mcewen, Renee Baran, Yishi Jin

Renee Baran

Axons are defined by the presence of presynaptic specializations at specific locations. We show here that loss-of-function mutations in the C. elegans gene syd-1 cause presynaptic specializations to form in the dendritic processes of GABA-expressing motor neurons during initial differentiation. At a later developmental stage, however, syd-1 is not required for the polarity respecification of a subset of these neurons. The SYD-1 protein contains PDZ, C2 and rho–GTPase activating protein (GAP)-like domains, and is localized to presynaptic terminals in mature neurons. A truncated SYD-1 that lacks the rhoGAP domain interferes with neurite outgrowth and guidance. Our data indicate that syd-1 …

Patenting Our Lives And Our Genes: Where Does Congress Stand? Public Commet To Ftc Hearing On Competition And Intellectual Property Law And Policy In The Knowledge-Based Economy, Thomas Horton

Thomas J. Horton

No abstract provided.

Molecular Dynamics Simulations Of Sodium Dodecyl Sulfate Micelle In Water: The Behavior Of Water, Chrystal Bruce, Sanjib Senapati, Max Berkowitz, L. Perera, M. Forbes

Chrystal D. Bruce

Using a 5 ns explicit atom molecular dynamics simulation of a 60 monomer sodium dodecyl sulfate micellar system containing 7579 TIP3P water molecules, the behavior of water in different electrostatic environments was examined. Structural evaluation of the system revealed that penetration of water molecules into the micelle was restricted to the headgroup region, leaving a 12 Å water-free hydrocarbon core. Water molecules near the headgroup exhibit a distortion of the water−water hydrogen bonding network due to headgroup oxygen−water hydrogen bond formation. The dynamic implications of this distortion are manifested in the decay of the dipole autocorrelation function, Φ(t) and translational …

Pseudomonas Aeruginosa Elastase Stimulates Erk Signaling Pathway And Enhances Il- 8 Production By Alveolar Epithelial Cells In Culture, Ali Azghani, J. W. Baker, S. Shetty, E. J. Miller, G. J. Bhat

Ali Azghani

Characterizing Gene Expression During Lens Formation In Xenopus Laevis: Evaluating The Model For Embryonic Lens Induction, Brian Walter, Jonathan Henry, Maria Carinato, Jonathan Schaefer, Adam Wolfe, Brian Walter, Kimberly Perry, Tricia Elbl

Brian Walter

Few directed searches have been undertaken to identify the genes involved in vertebrate lens formation. In the frog Xenopus, the larval cornea can undergo a process of transdifferentiation to form a new lens once the original lens is removed. Based on preliminary evidence, we have shown that this process shares many elements of a common molecular/genetic pathway to that involved in embryonic lens development. A subtracted cDNA library, enriched for genes expressed during cornea-lens transdifferentiation, was prepared. The similarities/identities of specific clones isolated from the subtracted cDNA library define an expression profile of cells undergoing cornea-lens transdifferentiation ("lens regeneration") and …

The Biophysics Of Leaf Growth In Salt-Stressed Barley. A Study At The Cell Level., Wieland Fricke, Winfried Peters

Winfried S. Peters

Molecular Dynamics Simulation Of Sodium Dodecyl Sulfate Micelle In Water: Micellar Structural Characteristics And Counterion Distribution, Chrystal Bruce, Max Berkowitz, Lalith Perera, Malcolm Forbes

Chrystal D. Bruce

An all-atom 5 nanosecond molecular dynamics simulation of a water-solvated micelle containing 60 sodium dodecyl sulfate monomers was performed. Structural properties such as the radius of gyration, eccentricity, micellar size, accessible surface area, dihedral angle distribution, carbon atom distribution, and the orientation of the monomers toward the micelle center of mass were evaluated. The results indicate a stable micellar system over the duration of the simulation. Evaluation of the structure and motion of the sodium counterions show (1) a long equilibration time (1 nanosecond) is required to achieve a stable distribution of counterions and (2) approximately 25% of the sodium …

The Expression Of The Let-7 Small Regulatory Rna Is Controlled By Ecdysone During Metamorphosis In Drosophila Melanogaster, Lorenzo Sempere, Edward Dubrovsky, Veronica Dubrovskaya, Edward Berger, Victor Ambros

Victor R. Ambros

In Caenorhabditis elegans, the heterochronic pathway controls the timing of developmental events during the larval stages. A component of this pathway, the let-7 small regulatory RNA, is expressed at the late stages of development and promotes the transition from larval to adult (L/A) stages. The stage-specificity of let-7 expression, which is crucial for the proper timing of the worm L/A transition, is conserved in Drosophila melanogaster and other invertebrates. In Drosophila, pulses of the steroid hormone 20-hydroxyecdysone (ecdysone) control the timing of the transition from larval to pupal to adult stages. To test whether let-7 expression is regulated by ecdysone …

Getting A Grip On Liprins, Renee Baran, Yishi Jin

Renee Baran

Two papers in this issue of Neuron add a new dimension to our understanding of liprin and LAR RPTP function during synapse formation. Kaufmann et al. (2002) present evidence that Dliprin-α interacts with Dlar to regulate presynaptic morphogenesis of the Drosophila neuromuscular junction. Wyszynski et al. (2002) demonstrate that mammalian liprin-α1 forms a complex with the PDZ protein GRIP and LAR in both pre- and postsynaptic compartments of hippocampal neurons and is required for the clustering of the GluR2 glutamate receptor in dendritic spines.

The Spectrin-Ankyrin Skeleton Controls Cd45 Surface Display And Interleukin-2 Production, Deepti Pradhan, Jon Morrow

Deepti Pradhan

Root Deployment And Shoot Growth For Two Desert Species In Response To Soil Rockiness, P. Martre, Gretchen North, E. Bobich, P. Nobel

Gretchen North

Soil texture, as well as the presence of rocks, can determine the water status, growth, and distribution of plants in arid environments. The effects of soil rockiness and soil particle size distribution on shoot and root growth, root system size, rooting depth, and water relations were therefore investigated for the Crassulacean acid metabolism leaf succulent Agave deserti and the C4 bunchgrass Pleuraphis rigida after precipitation events during the summer and winter/spring rainfall periods in the northwestern Sonoran Desert. The soils at the field site varied from sandy (<3% rocks by volume) to rocky (up to 35% rocks), with greater …

Plasma Membrane Aquaporins Play A Significant Role During Recovery From Water Deficit, P. Martre, R. Morillon, F. Barrieu, Gretchen North, P. Nobel, M. Chrispeels

Gretchen North

The role of plasma membrane aquaporins (PIPs) in water relations of Arabidopsis was studied by examining plants with reduced expression of PIP1 and PIP2 aquaporins, produced by crossing two different antisense lines. Compared with controls, the double antisense (dAS) plants had reduced amounts of PIP1 and PIP2 aquaporins, and the osmotic hydraulic conductivity of isolated root and leaf protoplasts was reduced 5- to 30-fold. The dAS plants had a 3-fold decrease in the root hydraulic conductivity expressed on a root dry mass basis, but a compensating 2.5-fold increase in the root to leaf dry mass ratio. The leaf hydraulic conductance …

Relation Of Ramet Size To Acorn Production In Five Oak Species Of Xeric Upland Habitats In South-Central Florida, Warren Abrahamson, J.N. Layne

Warren G. Abrahamson, II

No abstract provided.

Detecting Mitochondrial Permeability Transition By Confocal Imaging Of Intact Cells Pinocytically Loaded With Calcein, Rachel Jones, Alison Smail, Mark Wilson

Mark R Wilson

When studied in vitro, mitochondrial permeability transition (MPT) is associated with an increase in mitochondrial permeability to solutes up to 1500 Da in mass and a loss of electrical potential difference across the inner mitochondrial membrane (delta psi mit). The MPT has been implicated as being important in cellular calcium homeostasis, autophagy and cell death via necrosis and apoptosis. Thus, it is important to develop a valid technique for accurate measurement of this phenomenon in intact cells. We developed a procedure for the detection of MPT in intact cells that avoids disadvantages associated with earlier approaches. In this new technique, …

Evidence That Clusterin Has Discrete Chaperone And Ligand Binding Sites, Johnathon Lakins, Stephen Poon, Simon Easterbrook-Smith, John Carver, Martin Tenniswood, Mark Wilson

Mark R Wilson

Clusterin is the first identified extracellular mammalian chaperone and binds to a wide variety of partly unfolded, stressed proteins. Clusterin also binds to many different unstressed ligands including the cell surface receptor low density lipoprotein receptor-related protein-2 (LRP-2). It is unknown whether clusterin binds to all of these many ligands via one or more binding sites. Furthermore, the region(s) of clusterin involved in these many binding interactions remain to be identified. As part of an investigation of these issues, we expressed recombinant human clusterin in the yeast Pichia pastoris. The resultant protein had variable proteolytic truncations of the C-terminal region …

Alternative Mutations At Position 76 Of The Vacuolar Transmembrane Protein Pfcrt Are Associated With Chloroquine Resistance And Unique Stereospecific Quinine And Quinidine Responses In Plasmodium Falciparum, Roland A. Cooper, Michael T. Ferdig, Xin-Zhuan Su, Lyann M. B. Ursos, Jiabing Mu, Takashi Nomura, David A. Fidock, Paul D. Roepe, Thomas E. Wellems

Roland A. Cooper