Biol 446 - Kreig hw

Biol 446 - Kreig hw - Suneet Bhansali Biology 446 A. B. C....

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Suneet Bhansali Biology 446 Krieg, etc. C-P Heisenberg Paper A. In order to measure the strength of adhesions between fish embryo cells, Krieg used atomic force microscope as a single-cell force spectroscope. B. The AFM seems more like a micromanipulator that can measure forces exerted by its micro-needles because Krieg et al. used AFM to measure the forces between two isolated zebrafish germ-layer cells by bringing the two cells into contact until a specific force was reached. C. No, when adhesion forces between progenitors of the same type were measured, ectoderm cells showed less cohesion then mesoderm or endoderm cells. The ectoderm cells were the least cohesive. D. Cells of different types followed the ectoderm model in that they too had very little adhesive forces between them. E. In order to impair E-cadherin function, Krieg et al depleted the amount of Ca+2 ions from the medium and used morpholino antisense oligonucleotides to knock down E-cadherin levels. Then to test whether E-cadherin affected cell-cell adhesion, they measured the adhesion of ectoderm, mesoderm, and endoderm progenitors to substrates coated with E- cadherin. F. Mesoderm and endoderm progenitors adhered more to E-cadherin coated substrates than did endoderm progenitors. This allowed the team to deduce that adhesion of progenitors to cadherins is correlated with their cohesive properties. G. To test the strength of contractility of surfaces from ectoderm, mesoderm, and endoderm cells, the team deformed the surface of individual cells with a colloidal force probe and used AFM to record force indentation curves. Then the force-indentation curves were used to extract cell-cortex tension using cortical shell-liquid core or liquid droplet model. H. By measuring the differences in cell-cortex tensions of germ-layer progenitors in the
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This note was uploaded on 11/05/2011 for the course BIOL 446 taught by Professor Staff during the Fall '10 term at UNC.

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Biol 446 - Kreig hw - Suneet Bhansali Biology 446 A. B. C....

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