Neurobiology

• Competence

  Cells have the ability to become neural precursor.

  • exposed to the right combination of signals
• Commitment


  Cells have received the signals to become neural precursor cells. Cells can progress to become neurons or glia

  • occurs even if cells are exposed to signals that inhibit neural characteristics.
• Specification 


  Cells are neural precursor cells

  • cells can respond to signals that will repress neural characteristics.
• Determination 


  Cells will become a neuron by itself (autonomously) even if placed in a different region of the embryo.
• Differentiation

  Neural precursor cells become neurons.

  • became specialized cell type
  • look different
  • contain different functions
• Presumptive Mesoderm Cells

  • Initiate gastrulation
  • induce neural ectoderm
  • Upon invagination, the presumptive mesodermal cells signal to ectodermal layer to become neural ectoderm
• Richard Harland Lab (1992)

  1. Isolate organizer cells from gastrula. Purify mRNA
  2. Expose fertilized frog eggs to ultraviolet light. Irradiated eggs do not form an organizer or undergo gastrulation.
  3. Inject resulting blastulas with organizer mRNA- one type of mRNA for each blastula
• Injection of noggin mRNA into UV treated embryos does what?

  Restores body axis
• Animal Cap Experiment: noggin

  1. Dissected out animal cap cells (normally form epidermis)
  2. Placed in dish and allowed to autonomously develop. Cells became epidermal.
  3. Place animal cap cells with the addition of noggin protein. Cells developed into neural with no dorsal mesoderm