Downloaded 102 times
Uploaded byKashmeera N.A.
Cell aggregation and differentiation in dictyostelium007
The document summarizes the life cycle and cellular aggregation and differentiation process of Dictyostelium, a social amoeba. It has three stages: aggregation, migration, and culmination. During aggregation, thousands of solitary amoeba join together in streams in response to cyclic AMP signals. They migrate as a slug and the prestalk and prespore cells sort out, with prestalk cells becoming the stalk and prespore cells becoming spores. In culmination, the migrating slug forms a fruiting body with a stalk holding aloft a sorus of spores. The cells differentiate into their final fates depending on the stage of their cell cycle during starvation.
More Related Content
Cell aggregation and differentiation in dictyostelium007
- 1. CELL AGGREGATION AND DIFFERENTIATIONIN DICTYOSTELIUM KASHMEERA N.A.
- 2. DICTYOSTELIUM/CELLULAR SLIME MOULD/SOCIAL AMOEBA/MYXAMOEBA Solitaryhaploid amoeba. Becomes multicellular when nutrition starvation occurs.
- 3. LIFE CYCLE –3 STAGES • AGGREGATION. • MIGRATION. • CULMINATION
- 4. AGGREGATION. • Nutrient starvation→ myxamoeba express cAMP • Tens of thousands of myxamoebae join together to form moving streams of cells that converge at a central point.
- 5. • Each myxamoebamove towards c AMP for a minute & release c AMP of their own. • Movement is caused by change in cytoskeletal polarity brought about by c AMP. • After movement cell unresponsive for about 4 minutes. • This time, phosphodiesterase in ECM cleave c AMP in environment & make receptors free to receive another c AMP pulse. • C AMP pulse arrives as spiral waves,cell move one step towards center.
- 6. MIGRATION • Cells pileatop another→tight aggregate • Tip arises,bends →migrating slug/grex/pseudoplasmodium. • Grex with slimy sheath migrate from dark to light.
- 7. • During migration,most prestalk cells are anterior & → stalk. • Prespore cells posterior →spore • Some prestalk cells posterior→cup of sporesac & basal disc of stalk.
- 8. CULMINATION • Grex reachilluminated area→culmination starts. • Grex differentiate→frutingbody & stalk. • Fate of each cell depend on stage of cell cycle they were in while starvation. • Cell in S&early G2 → ↑Ca2+ →stalk • Mid/late G2 →↓Ca2+ →spore.
- 9. Response to cAMP • Diff. in prespore & prestalk cells. • Prespore: c AMP→β catenin→enter nucleus & express spore specific mRNA. • Prestalk(anterior): c AMP suppress this pathway & become stalk.
- 10. Proteins and lipidsimpo. In final differentiation. • Lipid: DIF1(chlorinated lipid) • Proteins: Trishanku, spore differentiation factors(SDF1&2).
- 11. FINALLY… • Stalk cellsdie • Prespore cells→spore
- 12. ALTRUISM IN DICTYOSTELIUM •Prestalk cells act as altruists which die for dispersion of kin cells - the prestalk cells.
- 13. DEVELOPMENTAL BIOLOGY –SCOTT F. GILBERT 9th EDITION
- 14.