Figure 9

Model for genome-nuclear membrane associations in C. elegans. (a) A model for large-scale chromosome arrangements mediated by the nuclear membrane. The large arm regions of autosomes are attached to the nuclear membrane, whereas the central portions of the chromosomes are looped out. For the X chromosome, the left arm is attached to the nuclear membrane, and the central and right portion of the chromosome are largely unattached. (b) A model for small-scale genome-nuclear membrane associations that underlie the large association domains. The small-scale associations often occur at regions with repetitive sequences and silent genes, and leave differentially sized gaps, which are likely looped out from the nuclear membrane. Among the loops, small loops are transcriptionally highly active.