QLS guest seminar - Friday 8 April

[Quantitative Life Sciences]

Friday, 8 April at 11:00

ICTP -  Central Area, 2nd floor, old SISSA building

Speaker: Jonathan DESPONDS - Laboratoire de Physique Téorique, École 
Normale Supérieure, Paris, France

Title:"Gene transcription dynamics in the early drosophila embryo"

Abstract:

Proper development of the adult fly relies on the correct spatial 
assignment of cell types during fly development. The different 
identities of cells are determined by sequentially expressing particular 
subsets of genes in different parts of the embryo.
Bicoid activated Hunchback is essential for Antero-Posterior patterning 
(among others).
The precision of the timing and spatial expression of the hunchback gene 
is regulated at the level of gene expression. This process involves the 
assembly of the transcription machinery and depends on the 
concentrations of the maternal gradients.
Using recent live imaging experiments that span several cell cycles we 
can access information on the dynamics of transcription initiation and 
gain insight into the dynamics of transcription.
We develop an analysis approach based on a tailor made time dependent 
autocorrelation function that overcomes all experimental and 
computational problems to quantify the dynamics of transcription 
initiation. Both eukaryotic and prokaryotic transcription can involve 
more than just switching between an active and inactive state, so we 
extend our analysis to increasing complexity that allows us to infer the 
effective number of transcription initiation steps and the rates for 
progressing through them.
We first discuss the accuracy and potential of our method on simulated 
data and then analyse live MS2-MCP traces from developing fruit fly 
embryos. We identify the bursty nature of transcription initiation from 
the hunchback promoter. We show that in the anterior region where Bicoid 
levels saturate the promoter transcription dynamics is extremely 
reproducible from cell cycle 11 to 13. We give a new method for 
computing the limiting accuracy of the antero-posterior boundary 
sharpness using only the parameters of our model.

Web page: http://indico.ictp.it/event/7841/

-- 
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste,  Italy
Tel. +39-040-2240623
e-mail: qls at ictp.it