Temperate Grassland  Temperatures in the winter often fall below –10ºC, while summers may be very hot, approaching 30ºC, and summer droughts are not uncommon.  Annual rainfall is generally between 25 and 100 cm, too low to support a forest but higher than that in deserts.  Prairie soils are among the richest in the world, having a nutrient content much greater than that of a typical forest soil.

TLS Online TPP Program

#Id: 10297

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 10298

#Unit 4. Cell Communication and Cell Signaling

T-cell education

TLS Online TPP Program

#Id: 10299

#Unit 4. Cell Communication and Cell Signaling

Lineage commitment

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

T-Cell Activation and Differentiation

TLS Online TPP Program

#Id: 10301

#Unit 4. Cell Communication and Cell Signaling

Three signals are required for activation of a naïve T cell

TLS Online TPP Program

#Id: 10302

#Unit 4. Cell Communication and Cell Signaling

Positive Costimulatory Receptors: ICOS

ICOS binds to another member of the growing B7 family, ICOS-ligand (ICOS-L), which is also expressed on a subset of activated APCs.

ICOS plays a key role in maintaining the activity of already differentiated effector and memory T cells.