Range: ±0.14 kb/min
||Fruit fly Drosophila melanogaster
||Garcia HG, Tikhonov M, Lin A, Gregor T. Quantitative imaging of transcription in living Drosophila embryos links polymerase activity to patterning. Curr Biol. 2013 Nov 4 23(21):2140-5. doi: 10.1016/j.cub.2013.08.054. p.2140 right column 2nd paragraphPubMed ID24139738
||"To validate that these fluorescence dynamics faithfully recapitulate actual transcription, [investigators] measure the rate of transcript elongation in live embryos. This is accomplished by using an additional reporter construct in which the MS2 stem loops are located at the 3’ end of the lacZ gene, instead of the 5’ end. Upon entering a n.c. [nuclear cycle], the onset of expression of the 3’ construct shows a clear delay with respect to the 5’ one (Figure 2A and Movie S2)."
||"The time delay measured over multiple embryos yields a rate of elongation r(elongation)=1.54±0.14 kb/min (Figure 2A). Measurements performed in Drosophila cell culture and in fixed embryos of 1.1–1.5 kb/min [ref 18] are in agreement with [investigators’] approach, suggesting that [their] technique gives direct access to the underlying transcriptional dynamics."