E N D
3. What are Planaria? Freshwater flatworms (phylum: Platyhelminthes)
Live in freshwater under leaves and stones
Avoid light (negative phototaxis)
Free living not parasites
Carnivores eat decaying meat, insects and larvae (egg yolks or liver in the lab)
1-20 mm in size
Long lived
Use sexual or asexual reproduction
4. Overview of Brown Planaria Dugesia tigrina
5. Planaria are complex organisms
9. Why study Planaria to learn about stem cells? Planaria have an amazing ability to regenerate parts of themselves
Planaria regeneration is a great model for demonstrating stem cell function and complexity of tissue regeneration
They can grow easily in the lab
10. Neoblast = Planaria Stem Cell 20-30% of all the cells in a planaria are Neoblasts.
Neoblasts divide by mitosis and can make more of themselves. They are the only dividing cells in planaria.
When a planaria is wounded, neoblasts migrate to the site and begin dividing
Neoblasts can become ANY cell the planaria needsnerve cells, flame cells, reproductive cells
12. Neoblasts and Stem Cells are Totipotent Totipotent Stem Cell
Blood Nerve Skin
They can become any cell type in the body
In Humans: Totipotent cells are limited to
early embryonic division
In Planaria: Neoblasts are always present
13.
turning on the
right genes at the
right time
in the cells that come from the dividing stem cells (neoblast). Regeneration requires
14. Care and Feeding of Planaria The water is very important! Fresh water from a pond, stream or lake is best; spring water is adequate
Keep cultures in a cool, dark place
Feed planaria at least once a week
Change the water twice a week, especially after feeding
After cutting them, the cultures should not be fed
15. Student Laboratory Investigation Each team will receive 3 planaria:
Experimental Planaria #1
Every team will cut this into half, separating
the anterior from the posterior halves.
Experimental Planaria #2
This will be cut in a manner determined by your team.
Control Planaria
This will not be cut.
16. Plenty of Planaria