John Georgiou

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Members of the Eph family of receptor tyrosine kinases control many aspects of cellular interactions during development, including axon guidance. Here, we demonstrate that EphB2 also regulates postnatal synaptic function in the mammalian CNS. Mice lacking the EphB2 intracellular kinase domain showed wild-type levels of LTP, whereas mice lacking the entire(More)
The molecular underpinnings of exploration and its link to learning and memory remain poorly understood. Here we show that inducible, modest overexpression of neuronal calcium sensor 1 (Ncs1) selectively in the adult murine dentate gyrus (DG) promotes a specific form of exploratory behavior. The mice also display a selective facilitation of long-term(More)
The intracellular signaling targets used by mammalian axon guidance receptors to organize the nervous system in vivo are unclear. The Nck1 and Nck2 SH2/SH3 adaptors (collectively Nck) can couple phosphotyrosine (pTyr) signals to reorganization of the actin cytoskeleton and are therefore candidates for linking guidance cues to the regulatory machinery of the(More)
Calcium measurements in the presynaptic terminal are essential in the investigation of mechanisms underlying neurotransmitter release. To enhance the genetic analysis of secretory mechanisms, we have developed Ca2+ imaging techniques for Drosophila larval motor nerve terminals. We studied Ca2+ signals in "big" (type Ib) and "small" (type Is) boutons that(More)
BACKGROUND Skeletons are formed in a wide variety of shapes, sizes, and compositions of organic and mineral components. Many invertebrate skeletons are constructed from carbonate or silicate minerals, whereas vertebrate skeletons are instead composed of a calcium phosphate mineral known as apatite. No one yet knows why the dynamic vertebrate skeleton, which(More)
Incretins are endogenous peptides released from the gastrointestinal tract into the circulation during a meal that potentiate glucose-stimulated insulin secretion. At present, there are two established incretins: glucose-dependent insulinotropic polypeptide (GIP) and the truncated glucagon-like peptides (tGLPs), which are now being investigated for use in(More)
We investigated signaling between individual nerve terminals and perisynaptic Schwann cells, the teloglial cells that cover neuromuscular junctions. When deprived of neuronal activity in vivo, either by motor nerve transection or tetrodotoxin injection, perisynaptic Schwann cells rapidly up-regulated glial fibrillary acidic protein. Addition of(More)
Huntingtin interacting protein 1 (HIP1) is a recently identified component of clathrin-coated vesicles that plays a role in clathrin-mediated endocytosis. To explore the normal function of HIP1 in vivo, we created mice with targeted mutation in the HIP1 gene (HIP1(-/-)). HIP1(-/-) mice develop a neurological phenotype by 3 months of age manifest with a(More)
Crustacean and insect neuromuscular junctions typically include numerous small synapses, each of which usually contains one or more active zones, which possess voltage-sensitive calcium channels and are specialized for release of synaptic vesicles. Strength of transmission (the number of quantal units released per synapse by a nerve impulse) varies greatly(More)
Fluorescence resonance energy transfer (FRET), measured by fluorescence intensity-based microscopy and fluorescence lifetime imaging, has been used to estimate the size of oligomers formed by the M(2) muscarinic cholinergic receptor. The approach is based on the relationship between the apparent FRET efficiency within an oligomer of specified size (n) and(More)