recently become interested in questions of transcriptional precision
100bp core promoter
snail = 100_/10 polII read count (‘pausing score’)
sog = 40 5
ths = 15+/- 4
weakly paused ths very small patches of twist expressing cells invaginate. moderately paused sog larger patches invaginate.
comment: most enhancers regulates some degree of elongation and pol, or most promoters do a little enhancer independent priming.
Live imaging of stochastic expression
movie build up: onset of transgene under weakly paused ths promoter. 1 hr.
paused promoters show very little bursting expression.
paused polII to achieve uniform (not necessarily faster) release of polII.
Non-paused promoters get nucleosome promoter exclusion more than paused promoters and are more bursty.
No evidence of memory — just burst
Questions:
Developmental systems where you want the noise?
Criteria for pausing, GC rich DPE, GAGA, good inr no TATA
comment: shadows – also surpressing noise also through affecting bursting frequency.
tup promoter doesn’t rescue gastrulation. Paused but produces fewer mRNA than ths.
Ciona
secondary heart field
neural crest.
hypothalamus pituitary link — two cell types in vertebrates, one cell type in