Lecture3Notes

Lecture3Notes - 1 Karina S. Cramer [email protected] 9/29/11...

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Unformatted text preview: 1 Karina S. Cramer [email protected] 9/29/11 Developmental Neurobiology N152 Neural induction leads to expression of proneuronal bHLH genes BMP signaling leads to inhibition of Sox transcription. Inductive signals inhibit BMP and permit transcription of Sox, which activates proneural genes. Other signaling pathways interact with these genes: Wnt, FGF Lateral inhibition is mediated by the neurogenic genes Notch and Delta When notch is inactive, ASC genes activate their own transcription and also Delta, a ligand for Notch. This cell would become a neuroblast. When Notch is activated by Delta expressed on a neighboring cell, Notch is cleaved. The intracellular domain binds to SuH (CSL) then the complex enters the nucleus and activate expression of HES, which represses both ASC and Delta expression. Genes that regulate neurogenesis e.g., Achaete-scute: mutants have fewer neuroblasts. e.g., Notch, Delta: Mutants have too many neuroblasts. Each cluster of proneural cells yields a single neuroblast 2 Whole-mount in situ hybridization Pax-6 label in a developing embryo Courtesy of Scott Gilbert Immunohistochemistry Process of localizing proteins in cells by exploiting the principle that antibodies bind to speciFc antigens. Direct Method (not sensitive) Indirect Method (sensitive) Confocal analysis of growth of hippocampal neurons after 7-days in- vitro. Immunostaining reveals neurons via a dendrite-speciFc marker , while the cytoskeletal Flaments of f-actin highlighy structures rich in f-actin, such as growth cones at tips of neuritis. Courtesy of the London Centre for Nanotechnology. Regionalization Regions within the nervous system acquire distinct identities. This process results in large part from gradients of signaling molecules and from distinct expression patterns that result from these signals. DeFning the anterior-posterior axis Hox genes Other factors Brain organizers DeFning the dorsal-ventral axis Patterning in the cerebral cortex Regionalization of the neural tube along the anterior-posterior axis yields the forebrain, midbrain, hindbrain, and spinal column. These regions are further subdivided, and relate to the anatomical organization of the mature brain. Vertebrate neural tube: anterior-posterior regions 3 Anterior-posterior regionalization in fies A-P axis is deFned by mRNA ` s deposited into the egg. Maternal eect genes induce expression o Gap genes. Combinations o Gap genes infuence l pair rule z genes, which aect alternate segments. Segment polarity genes deFne the A-P axis within a segment. Homeotic genes deFne segment identity. Hox gene cluster is needed or segment identity In beetles, deletion o this cluster give the right number o segments, but they all have the morphology o the antennal segment....
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This note was uploaded on 12/13/2011 for the course BIOSCI 93 taught by Professor Staff during the Fall '11 term at UC Irvine.

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Lecture3Notes - 1 Karina S. Cramer [email protected] 9/29/11...

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