Hox genes and neuronal differentiation during leech development.
Item
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Title
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Hox genes and neuronal differentiation during leech development.
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Identifier
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AAI3310769
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identifier
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3310769
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Creator
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Gharbaran, Rajendra.
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Contributor
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Adviser: Gabriel O. Aisemberg
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Date
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2008
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Molecular | Biology, Neuroscience | Biology, General
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Abstract
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One of the most fascinating and important biological findings over the past two decades was the discovery of the Hox gene family. These genes code for transcription factors that regulate the expression of other genes to bring about the complex organization of the nervous system, their main site of expression. Using an improved technique for antibody purification, I carried out a detailed characterization of the expression of two leech Hox genes (Lox1 and Lox2) and studied the role of Lox1 in the differentiation of a pair of specialized motor neurons (RPE neurons) that innervate the male sex organ.;Lox1 expression was detected in segmental ganglia R4 to M13. Lox2 expression was detected in segmental ganglia M6 to M21. From M8 to M13, the number of Lox1+ nuclei was found to decrease while the number of Lox2 + nuclei remained large. These observations suggest that Lox2 may down-regulate Lox1 expression.;In addition, double-staining experiments led to the identification of several central neurons that express Lox1 or Lox2 . These experiments used antibodies that recognize neuronal markers (FMRFamide, serotonin, enkephalin, and Laz1-1 antigen) in combination with LOX1 and LOX2 antibodies. The Lox1-positive (Lox1+) neurons identified in this manner included the AMS and PMS neurons of M2 and M3, the RPE neurons of M6, the cell 261 of M7-M12, and the HAL neurons of M4. Among the identified neurons that expressed Lox2 were the Rz neurons of M8-M21, the PMS neurons of M7-M21, the RMV and CV neurons of M7-M21, and the AP, NUT, and HAL neurons of M7-M17.;Lox1 expression was also detected in the primordia of the male and female sex organs. Because the sex organs are known to provide guidance cues to the axons of neurons in the nearby sex ganglia (M5 and M6), this observation suggested that Lox1 may control the expression of signaling molecules (by the sex organs) that would be required for axon guidance, target recognition and neuronal differentiation.;RNA interference (RNAi) experiments suggested a role for Lox1 in controlling the differentiation of the RPE neurons, segment-specific motor neurons of ganglion M6 that innervate the male sex organ. Knockdown of Lox1 expression caused a decrease in FMRFamide staining in the RPE neurons, as well as axonal defects.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
