Just like Origami, DNA is intricately folded inside of a cell’s nucleus. DNA compaction differs in distinct cell types, like somatic and germ cells, and is typically tightly controlled by the function of Cohesin, a protein complex that mediates sister chromatid cohesion and DNA looping. In this issue of Genome Research, a study from the Peters lab (IMP Vienna) shows that in frog and human sperm, genomic DNA is not folded by cohesin, as it is in somatic cells, possibly because in these cells DNA is densely packaged by specialized sperm proteins called protamines.

This important paper implies that in sperm from all vertebrate species genomic DNA might be packaged very differently from how it is folded in somatic cells. Curious about the details? Check out the paper.