MODELLING OF POLYCOMB-DEPENDENT CHROMOSOMAL INTERACTIONS INVOLVED IN DROSOPHILA GENE SILENCING

Abstract

The conditions of the chromosomes inside the nucleus in the Rabl configuration have been modelled as self-avoiding polymer chains under restraining conditions. To ensure that the chromosomes remain stretched out and lined up, we fixed their end points to two opposing walls. The numbers of segments N, the distances d1 and d2 between the fixpoints, and the wall-to-wall distance z (as measured in segment lengths) determine an approximate value for the Kuhn segment length kl. We have simulated the movement of the chromosomes using molecular dynamics to obtain the expected distance distribution between the genetic loci in the absence of further attractive or repulsive forces. A comparison to biological experiments on Drosophila Melanogaster yields information on the parameters for our model. With the correct parameters it is possible to draw conclusions on the strength and range of the attraction that leads to pairing.