This is a Shannon Award providing partial support for the research projects that fall short of the assigned institute's funding range but are in the margin of excellence. The Shannon Award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. The abstract below is taken from the original document submitted by the principal investigator. Neuritogenesis governs developmental migration, axonogenesis and dendritic arborization of neurons, CNS phenomena which are aberrant in experimental FAS. Neuritogenesis depends mechanistically upon 1) plasma membrane-substratum adhesion and 2) neurital plasma membrane extension. The simple gangliosides G-M3 and G-D3 promote plasma membrane integrin- regulated and carbohydrate shear-modulated substrate adhesion. Syntheses of G-M3/G-D3 by IC-Golgi derived exofacial (ecto) sialyl transferases relocated within EGF-induced recycling endosomes, which are formed by EGF-induced endocytosis, may be a unique neuronal mechanism for promoting adhesion, by producing targeted localization of plasma membrane G-M3/G- D3. Chronic exposure of cells to ethanol reduces EGF-receptor (EGFR) endocytosis, thus limiting endosomal G-M3/G-D3 re-tailoring, and weakening adhesion loci. The effects of chronic ethanol exposure on G- M3/G-D3 sialylation in EGFR-induced endosomes will be quantitated in both a chick neuron culture and in an in ovo FAS model. Neurite plasma membrane extension requires addition to the plasma membrane of Golgi-derived plasma membrane elements with a very high structural content of neuritogenic (terminally-sialylated gangliotetraosyl ceramide) ganglioside glycoforms, particularly the major gangliosides G-T1b, G-Q1b. Attenuated neuritogenesis results from inhibition of cytoskeletally regulated anterograde Golgi biosynthesis of G-T1b, G-Q1b. Dose-and time-dependent chronic ethanol-induced inhibition of biosynthesis of these gangliosides in neuron culture and a parallel whole embryo in ovo FAS model will be traced with [3H]ManNAc, as an obligate sialic acid precursor. Vulnerability of the differentiating embryonic CNS neuron to chronic ethanol-induced biosynthetic inhibition of sialylation of key neuronal gangliosides will be documented in detail. Evaluation will be made of exogenous re-supply of the neurital plasma membrane with building block gangliosides (G-T1B/G-Q1b) in neurite preservation A) in neuron culture and B) in vivo in embryonic chick brain, during chronic exposure to ethanol.
