Projects in my section aim at clarifying the mechanisms of synapse formation and function, with an emphasis on the nicotinic synapses. Nicotinic receptors are found widely in the nervous system, and play important roles in various aspects of behavior and pathological conditions. Specifically, their involvement has been strongly implicated in alcoholism. We use the nervous system of zebrafish as the experimental model. Some experiments focus on the neuromuscular junction, while others directly examine the brain. All projects combine genetics, confocal microscopy, molecular biology and cellular physiology. We presented two posters in the Neuroscience Meeting held in Chicago, 11/2009. Titles of posters are """"""""Kinematic analysis of larval zebrafish locomotion in ethanol"""""""" and """"""""Formation of spinal network determined by domain-specific Pax genes"""""""". The section had its first BSC review in 09/2010. We have on-going collaborations with Dr. Paul Brehm at the Oregon Health and Science University, Dr. Alan Davidson at the Massachusetts General Hospital, Dr. Koichi Kawakami at the National institute of genetics in Japan, Dr. Ralph Nelson at NINDS, Dr. Jerry Yakel at NIEHS, Dr. Roger Papke at the University of Florida, and Dr. Stephen Ikeda and Dr. Stephen Vogel at NIAAA. Ms. Alison Delargy finished her tenure of IRTA fellow at NIAAA. She was accepted in the College of Osteopathic medicine, University of New England, where she is undergoing training to be a medical doctor. Dr. Hiromi Ikeda was newly hired in FY2010 to fill the vacant position. She worked as a postdoc in the labs of Dr. Kerppola in the University of Michigan and Dr. Ajay Chitnis at NICHD/NIH before joining MSS in 03/2010. A manuscript entitled """"""""Formation of spinal network in zebrafish determined by domain-specific Pax genes"""""""" is under revision for the Journal of Comparative Neurology. The abstract is as follows: In the formation of the spinal network, various transcription factors interact to develop specific cell types. Using a gene trap technique, we established a stable line of zebrafish in which the red fluorescent protein (RFP) was inserted in the pax8 gene. RFP insertion marked putative pax8-lineage cells with fluorescence and abolished pax8 expression in homozygous embryos. Pax8 homozygous embryos displayed defects in the otic vesicle, as previously reported in studies using morpholinos. The pax8 homozygous embryos survived to adulthood in contrast to mammalian counterparts that die prematurely. RFP is expressed in the dorsal spinal cord. Examination of the axon morphology revealed that RFP(+) neurons include Commissural Bifurcating Longitudinal (CoBL) interneurons, but other inhibitory neurons such as Commissural Local (CoLo) interneurons and Circumferential Ascending (CiA) interneurons do not express RFP. We examined the effect of pax2a/pax8 gene ablations on interneuron development. In pax8 homozygous embryos, the RFP (+) cells undergo differentiation similar to that of pax8 heterozygous embryos, and the swimming behavior remained intact. In contrast, the RFP (+) cells of pax2a/pax8 double mutants displayed altered cell fates. CoBLs were not observed. Instead, RFP (+) cells exhibited axons descending ipsilaterally: a morphology resembling that of V2a/V2b interneurons. In this study we used the gene trap technique in zebrafish to label a population of neurons as well as to inhibit specific gene expression in those neurons. It revealed the identity of putative pax8-lineage interneurons in the spinal cord and roles of pax2a/pax8 in the network formation of the spinal cord. Another paper in collaboration with Dr.Stepehn Ikeda's lab entitled """"""""Identification and modulation of voltage-gated Ca2+ current in zebrafish Rohon-Beard neurons"""""""" was submitted and is under revision for the Journal of Neurophysiology. A third paper studying adult renal progenitor cells in collaboration with Dr.Davidson's group was submitted and is under review.
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