Lecture 22 - Developmental Genetics 11-21

Lecture 22 - Developmental Genetics 11-21 - Developmental...

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Developmental Genetics Principles of Biology Lecture 22 Prof. David Fitch © 2007 D. Fitch
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Developmental genetics Development: from one cell, a multicellular organism Model systems amenable to experimentation big surprise to developmental biologists in the 1990s (but predicted by evolution): they all share similar mechanisms and genes Processes of development Different cells result from differential expression of same genome genomic equivalence, stem cells Hierarchical gene regulation controls development Factors influencing this differential expression cytoplasmic determinants and cell-cell interactions (signaling, "induction") Pattern formation leads to fields of different cells specific examples from several model systems These developmental mechanisms have changed during evolution, leading to diversity of form
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Model systems Attributes of good model systems lab-friendly (easy to maintain) fast generation times easily scored traits representative of other organisms
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Caenorhabditis elegans pharynx ring intestine gonad sperm vas deferens male tail spermathecae vulva cloaca anus rectum phasmid stoma uterus embryo intestine Good for genetics short generation time (3.5-4 days), many progeny, can self or cross Cell lineage is completely known for both sexes transparent, foundation for development at single-cell resolution, allows genetics of cell lineage (e.g., programmed cell death) Small genome size (<100 Mbp) Not "soil nematode"! but prob. human commensal (compost)
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Developmental processes Fertilization Cleavage to make blastula Morphogenesis (change in cell shape and position) to make gastrula During these stages, many events occur, such as: cell determination and pattern formation often involves cell signaling (induction and inhibition) cell differentiation (including morphogenesis, cell death, and other fates)
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terms pluripotent: able to differentiate into different cell types competent: able to adopt a particular cell fate determination: progressive restriction of developmental potential, commitment to particular cell fate (or set of potential fates) differentiation: attainment of a particular "cell fate" or cell function cell lineage: division pattern of cells stem cell lineage: produces a stem cell and a cell with restricted fate induction: positive response to a cell-cell signaling event lateral inhibition: prevention, via signaling, of particular cell fates cytoplasmic determinants: factors inherited from mother cell that influence fates of daughter cells; may localize asymmetrically axis: axis along which cells will differentiate (e.g., anteroposterior) pattern formation: differentiation of fields of cells along an axis
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Genomic equivalence Two alternative hypotheses about developmental control: Keep the same genome all the time, just change gene expression Prediction:
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This note was uploaded on 04/29/2008 for the course BIO V23.0011 taught by Professor Fitch during the Spring '08 term at NYU.

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Lecture 22 - Developmental Genetics 11-21 - Developmental...

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