Fig. 1

Top: A schematic showing the key elements of the model nucleus of D. melanogaster. Bottom panels: The four initial configurations (bottom panels) of the D. melanogaster chromosome arms [2 L (red), 2R (orange), 3 L (yellow), 3R (green), X (blue) and 4 (cyan)] that serve as the starting points of the simulations described here. The nucleolus is shown as a gray sphere (on bottom panels). The arms are fully “territorial” at the beginning of each simulation. The initial configurations correspond to the different mutual arrangements of the chromosome arms (nucleus topologies) experimentally determined by Hochstrasser et al. [108]. From left to right: CIS-X6S, CIS-X7N, TRANS-X3S and TRANS-X4N nucleus topologies. Here, the “CIS” configuration refers to chromosome arrangement in which the two “R” arms (orange and green) or two “L” arms (red and yellow) of autosomes are next to each other in 3D space, while “TRANS” arrangement is complementary to it