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Life as a worm-- the nematode C. elegans

Life as a worm-- the nematode C. elegans. Life as a worm-- the nematode C. elegans. Hermaphrodites do it by themselves. An entire C. elegans hermaphrodite worm consists of exactly 959 cells EVERY SINGLE TIME, allowing one to follow the cell lineage. Here’s how it works.

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Life as a worm-- the nematode C. elegans

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  1. Life as a worm-- the nematode C. elegans

  2. Life as a worm-- the nematode C. elegans

  3. Hermaphrodites do it by themselves

  4. An entire C. elegans hermaphrodite worm consists of exactly 959 cells EVERY SINGLE TIME, allowing one to follow the cell lineage.

  5. Here’s how it works

  6. Was that too fast? Let’s look a bit more closely

  7. Most lineages do not consist of single tissue types but the germline and the gut both arise from single founder cells

  8. Most lineages do not consist of single tissue types but the germline and the gut both arise from single founder cells

  9. Within this lineage is the secret of embryonic development

  10. Even cell death is programmed into the lineage C. elegans was used to identify the machinery that regulates programmed cell death in ALL animals

  11. The Nobel Prize in Physiology or Medicine 2002 "for their discoveries concerning ’ genetic regulation of organ development and programmed cell death'" Sidney Brenner H. Robert Horvitz John Sulston

  12. How can lineage control cell fate? One mechanism is through asymmetric segregation of determinants

  13. A determinant within the P granules is asymmetrically segregated into one cell at the 16-cell stage. That cell is the progenitor of the germline! DNA P granules Gilbert 8.33

  14. In par mutants P granules are found in ALL daughter cells wildtype par-3 mutant

  15. Mutations can alter lineages in many ways

  16. Example #1- lin-22 Changes in the pattern of cell division

  17. Example #1- lin-22 Changes in the pattern of cell division lin-22 is homologous to the Drosophila pair-rule gene hairy

  18. Example #2- lin-14 Changes in the timing of cell division L1 L2 L1 L2 L1 L1 L1

  19. Scientists studying regulation of lin-14 were the first to identify functions for microRNAs

  20. And the heterochronic regulator lin-28 can be part of the recipe For making “induced pluripotent stem cells”

  21. The nematode also provides a great model for organogenesis: e.g., Building the vulva Vulva

  22. Vulva Formation in C. elegans A paradigm for organogenesis One inducing cell Three receiving cells 22 cells One complete organ

  23. The key players One gonadal anchor cells (AC) 6 vulval precursor cells (VPCs)

  24. Cell ablations help define the key players

  25. The anchor cell (AC) signals to the vulval precursor cells (VPCs) to adopt vulval fates

  26. All cells are created equal (or, the road to fame is paved with dead bodies)

  27. The “bag of worms”

  28. The vul mutations helped define the RTK-Ras pathway, which is mutationally activated in about half of all human tumors

  29. Does this remind you of anything we learned earlier?

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