Not just a bunch of noodles: Defining the timeline of chromosome organization

What is it about?

Many of us imagine the DNA inside our cells as a jumble of noodles. However, DNA is more organized than this inside the nucleus, with chromosomes occupying distinct nuclear territories. It is unclear though whether this organization is always present or whether it appears at some point during development after fertilization of the egg. We studied chromosome organization by observing the mobility of chromosomes inside in the nucleus in developing nematode embryos from the 2-cell to the 48-cell stage. We found that chromosome mobility decreases in 8-cell embryos, indicating the establishment of chromosome organization at this point.

Featured Image

Why is it important?

Chromosome organization in the nucleus is important for gene expression and may have other purposes as well. For example, we found that in nematodes, the timing of chromosome organization coincides with the appearance of epigenetic marks, which regulate gene expression, and of a nuclear domain called the nucleolus. Now that we have identified the precise timing of nuclear chromosome organization in nematodes, we will be able to conduct future studies to determine the factors responsible for initiating this organization.