  An active loop-extrusion mechanism is regarded as the main
out--of--equilibrium mechanism responsible for the structuring of
megabase-sized domains in chromosomes. We developed a model to study the
dynamics of the chromosome fibre by solving the kinetic equations associated
with the motion of the extruder. By averaging out the position of the extruder
along the chain, we build an effective equilibrium model capable of reproducing
experimental contact maps based solely on the positions of extrusion--blocking
proteins. We assessed the quality of the effective model using numerical
simulations of chromosomal segments and comparing the results with
explicit-extruder models and experimental data.
