bicd130_06_lecture11r

Bicd130_06_lecture11 - BICD 130 Embryos Genes and Development Midterm Exam Pick-up Jackie Vignes 4334 Bonner Hall(82)2-0654 10 AM 4 PM The

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Unformatted text preview: BICD 130 Embryos, Genes, and Development Midterm Exam Pick-up Jackie Vignes 4334 Bonner Hall (82)2-0654 10 AM - 4 PM The combinatorial potential of alternative splicing The Drosophila Dscam gene can theoretically produce 38,016 isoforms Dscam (Down syndrome cell adhesion molecule) is involved in controlling axon targeting in the fly nervous system Mechanisms of Differential Gene Activity Differential gene transcription Selective nuclear RNA processing Differential mRNA stability Selective mRNA translation Differential protein modification Differential protein stability mRNA for the milk protein casein is stabilized in the presence of the hormone prolactin t1/2= 28.5 hrs t1/2= 1.1 hrs The lin-4 microRNA negatively regulates accumulation of lin-14 mRNA in the worm C. elegans Bagga et al. (2005) Cell 122: 553-563 Science 294, 853-858 (2001) MicroRNAs ("miRs") encoded in the human genome Mechanisms of Differential Gene Activity Differential gene transcription Selective nuclear RNA processing Differential mRNA stability Selective mRNA translation Differential protein modification Differential protein stability Sea urchin: Ribosomes are recruited into polyribosomes after fertilization Sea urchin: Early protein synthesis is programmed by stored maternal mRNAs Actinomycin D is an inhibitor of transcription Surf clam: Masked maternal mRNA for ribonucleotide reductase (RR) Masking by inclusion in mRNP (ribonucleoprotein) particle A wide variety of both protostomes and deuterostomes use translational control of stored maternal mRNAs Localization of maternal mRNAs in Xenopus Progressive localization of Vg1 mRNA in developing oocytes The Vg1 protein is a member of the TGF- family of signaling molecules, and is required for proper embryonic patterning, including mesoderm induction Mechanisms of Differential Gene Activity Differential gene transcription Selective nuclear RNA processing Differential mRNA stability Selective mRNA translation Differential protein modification Differential protein stability Post-translational modification can regulate protein activity FGF FGFR PKC myogenin Structure of a basic helix-loop-helix (bHLH) protein dimer Progressive Establishment of Cell Fate COMMITMENT: Restriction of developmental fate potential (not necessarily irreversible) DIFFERENTIATION: Final expression of specialized cell characteristics Two Ways of Specifying Cell Fate The European Way: Who you are depends on who your parents are The American Way: Who you are depends on who your neighbors are Modes of Cell Fate Specification AUTONOMOUS: Factors expressed by, or localized within, the cell itself ("determinants") direct its commitment to a specific fate CONDITIONAL: External factors (such as interaction with other cells) specify the cell s fate Modes of Cell Fate Specification AUTONOMOUS: Factors expressed by, or localized within, the cell itself ("determinants") direct its commitment to a specific fate CONDITIONAL: External factors (such as interaction with other cells) specify the cell s fate Larval form of ascidian (sea squirt) Ascidian: Bilateral cleavage symmetrically partitions regions of colored cytoplasm associated with different cell fates Cell fates are autonomously specified in the 8-cell ascidian embryo Autonomous differentiation of muscle tissue is associated with inheritance of "yellow crescent" cytoplasm acetylcholinesterase Artificial redistribution of yellow crescent cytoplasm confers muscleforming capacity on additional blastomeres Rearrangement of cytoplasm following fertilization in the ascidian creates the yellow crescent What is the ascidian muscle determinant? Nature 409: 724-729 (2001) Localization of macho-1 mRNA mimics that of the muscle determinant Ectopic injection of macho-1 mRNA results in ectopic formation of muscle cells Front: myosin Back: AchE Modes of Cell Fate Specification AUTONOMOUS: Factors expressed by, or localized within, the cell itself ("determinants") direct its commitment to a specific fate CONDITIONAL: External factors (such as interaction with other cells) specify the cell s fate ...
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This note was uploaded on 04/29/2008 for the course BICD 130 taught by Professor Tour during the Fall '07 term at UCSD.

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