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3-6-13_germ cells and germ plasm

If pole cells form they should be of the second

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Unformatted text preview: donor. If pole cells form, they should be of the second embryo’s genotype Wolpert et al., 2e. Fig. 12.13 UV treated: no pole cells Wolpert et al., 2e, Fig. 12.13 We are looking for cells of the second genotype in the sperm/oocytes of the final flies. Result: functional germ cells! Testing whether oskar mRNA is sufficient to recruit germ plasm oskar mRNA is part of a scaffold for germ plasm in Drosophila Anterior components Staufen protein + oskar mRNA form “scaffold” Nurse cells Anterior components We make an engineered form of the oskar gene that encodes oskar + the 3’-UTR of bicoid. bicoid mRNA is normally at the anterior, so the gene, if expressed in mothers, will cause some oskar to be at the anterior Wolpert, 2e, Fig. 12.15 Modified from Gilbert 8e, Fig. 9.8 Testing whether oskar mRNA is sufficient to recruit germ plasm Testing whether oskar mRNA is sufficient to recruit germ plasm Pole cells at anterior A Normal pole cells at posterior P Conclusion: oskar mRNA is sufficient to recruit pole plasm capable of forming pole cells Wolpert, 2e, Fig. 12.15 Wolpert, 2e, Fig. 12.15 Expression of oct4 mRNA correlates with totipotency and ability to form germ cells in mammals Germ cells migrate directionally in vertebrates Primordial germ cells migrate into the genital ridge (gonad primordium) Guidance is mediated in part by a chemokine, SDF-1. PGCs sense SDF-1 via CXCR4, a receptor. Gilbert, 9e, Fig. 16.8 * Germ cells form via cell-cell interactions in mammals Primordial germ cells migrating into gonad Gilbert, 9e, Fig. 16.14 Germ cells form from four clusters in zebrafish germ cell precursors migrate as clusters into the developing gonad, a process also mediated via SDF-1 and CXCR4 Gilbert, 9e, Fig. 16.12 SDF-1 or CXCR4 knockdown perturbs germ cell migration in zebrafish control Courtesy Erez Raz CXCR4 MO SDF1 MO...
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