3 SANES CH 3 2009 + GI_1 (2)

3 SANES CH 3 2009 + GI_1 (2) - Development of the Nervous...

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Development of the Nervous System Chapter 3 Sanes, Reh and Harris Cell Division, Neuronal Birthdates, and Neuronal Migration
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Important issues in chapter 3 1. Cell division in the vertebrate neural tube takes place near the ventricular surface. 1. Precursor cells in the neural tube only produce neurons, astrocytes and oligodendroglia. 3. After the last neuroblast cell division, the immature neurons migrate to a location close to or far from the ventricle. 4. New neurons are produced after birth in all vertebrate brains.
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G1 phase = RNA and protein synthesis = 6-12 hr S phase = Replication of DNA = 6-8 hr G2 phase = hanging around with 4n DNA =3-4 hr M phase = cell division (mitosis) = 1 hr HistoneH3 labels Dividing cells Immature Neurons that incorporated BrdU Bromodeoxyuridine (BrdU) is a synthetic nucleoside analog of uridine that is incorporated into DNA during the S phase and labels dividing cells which can be visualized by immunocytochemistry. For this purpose it is analogous to 3H thymidine. Axons Contain neurofilaments V outer limiting layer
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Birth is on E 20-21 in mice RNA and Protein Synthesis is prolonged in the G1 phase DNA Replication Data from mouse cortex in which gestation is 21 days Progenitor cell cycle during embryogenesis Rate and number of divisions are controlled by Cyclins in all living things
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Cyclins are so named because their concentration varies in a cyclical fashion during the cell cycle; they are produced or degraded as needed in order to drive the cell through the different stages of the cell cycle. Thus, cyclins control the rate and number of cell divisions through activation of a type I cyclin- dependent kinase (Cdk). Kinases are gene products which, when activated, phosphorylate other proteins: type I = phosphorylate proteins at a serine or threonine amino acid type II = phosphorylate proteins at a tyrosine amino acid Phosphatases = proteins that de=phosphorylate phosphoproteins Cyclin A+B Cyclin E Cyclin gene names vary with species Cyclin gene expression controls the rate, duration and frequency of cell division Cyclin D
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Normal mouse retina Cyclin D - KO P27kip KO This is a negative regulator of cyclins Both Cyclin D And P27kip - KO Cyclins are regulatory subunits that activate cyclin-dependent kinases (Cdk) with expression epochs linked to the cell division cycle Normally Cyclin D expression initiates repeated cell division during the G1 phase by activating cyclin-dependent kinases (Cdk’s)
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Important issues in chapter 3 1. Cell division in the vertebrate neural tube takes place near the ventricular surface. 1. Progenitor cells in the neural tube produce only
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This note was uploaded on 03/06/2010 for the course NSC 269 taught by Professor Ebner during the Spring '10 term at Vanderbilt.

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3 SANES CH 3 2009 + GI_1 (2) - Development of the Nervous...

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