5 research outputs found
Molecular Identification and Reconstitution of Depolarization-Induced Exocytosis Monitored by Membrane Capacitance
Regulated exocytosis of neurotransmitters at synapses is fast and tightly regulated. It is unclear which proteins constitute the “minimal molecular machinery” for this process. Here, we show that a novel technique of capacitance monitoring combined with heterologous protein expression can be used to reconstitute exocytosis that is fast (<0.5 s) and triggered directly by membrane depolarization in Xenopus oocytes. Testing synaptic proteins, voltage-gated Ca(2+) channels, and using botulinum and tetanus neurotoxins established that the expression of a Ca(2+) channel together with syntaxin 1A, SNAP-25, and synaptotagmin was sufficient and necessary for the reconstitution of depolarization-induced exocytosis. Similar to synaptic exocytosis, the reconstituted release was sensitive to neurotoxins, modulated by divalent cations (Ca(2+), Ba(2+), and Sr(2+)) or channel (Lc-, N-type), and depended nonlinearly on divalent cation concentration. Because of its improved speed, native trigger, and great experimental versatility, this reconstitution assay provides a novel, promising tool to study synaptic exocytosis
Landau-Ginzburg Realization of Open String TFT.
We investigate B-type topological Landau-Ginzburg theory with one variable,
with D2-brane boundary conditions. We find that the allowed brane
configurations are determined in terms of the possible factorizations of the
superpotential, and compute the corresponding open string chiral rings. These
are characterized by bosonic and fermionic generators that satisfy certain
relations. Moreover we show that the disk correlators, being continuous
functions of deformation parameters, satisfy the topological sewing
constraints, thereby proving consistency of the theory. In addition we show
that the open string LG model is, in its content, equivalent to a certain
triangulated category introduced by Kontsevich, and thus may be viewed as a
concrete physical realization of it.Comment: Latex, 29p, 1 fig, refs added, various minor corrections, example
section droppe