(main axis flattened)

Capitulum (head)

The peduncle is reduced to a flat, concave, or convex disc, the receptacle that bears small sessile and centripetally arranged flowers called florets, surrounded by an involucre of bracts

Examples: Helianthus annuus (Sunflower), Zinnia, Tagetes erecta (Marigold), Cosmos, Mimosa pudica (touch-me-not), Acacia, etc.

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Within the nucleus, R-Smads are modified by:

Phosphorylation of linker domains

Acetylation of MH1 domains

Dephosphorylation of the C-terminal serines by nuclear

phosphatases

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BMP proteins, activate a different set of receptors that are similar to the TGF-β RI and RII proteins but phosphorylate other R-Smads, Smad1, Smad5, & Smad8

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Smad4 was originally called DPC (deleted in pancreatic cancer)

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Negative regulators of TGF-β signaling are induced by TGF-β signaling (Example of Negative feedback): 

Ski 

SnoN 

I-Smads (Smad7)

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SnoN and Ski trigger abnormal cell proliferation by blocking the Smad-complex.

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#XL - T Zoology