The PHYA gene is transcriptionally active in dark-grown seedlings, but its expression is strongly inhibited in the light in monocots.

TLS Online TPP Program

#Id: 3853

#Unit 5. Developmental Biology

In D. discoideum cAMP phosphodiesterase RegA plays a crucial role in regulating intracellular cAMP levels cells & level of PKA activity.

TLS Online TPP Program

#Id: 3854

#Unit 5. Developmental Biology

RegA is activated by phosphorylation of an aspartate in its response regulator domain.

TLS Online TPP Program

#Id: 3855

#Unit 5. Developmental Biology

Dictyostelia (social amoebas)

solitary haploid amoebae live on decaying logs, eating bacteria and reproducing by binary fission.

TLS Online TPP Program

#Id: 3856

#Unit 5. Developmental Biology

Dictyostelium can utilize one of three survival strategies when food starvation-

(1) Microcyst formation, favoured in dark & wet conditions, or ammonia levels are high.
(2) Zygote formation, favoured in dark & wet conditions, & triggered by ethylene produced by the cells.
(3) Cell aggregation & differentiation

TLS Online TPP Program

#Id: 3857

#Unit 5. Developmental Biology

Phosphorylation of RegA is mediated by sensor histidine kinases/phosphatases which either phosphorylate or dephosphorylate themselves on a histidine residue when a signal molecule binds to their sensor domain.

TLS Online TPP Program

#Id: 3858

#Unit 5. Developmental Biology

Cell Aggregation & Differentiation is common to all Dictyostelids.
It consists of an interconnected programme of cell movement and cell differentiation.