Using a microscope invented at the Marine Biological Laboratory (MBL), a collaborative team of biologists, instrument developers, and computational scientists has for the first time measured the density of a relatively inscrutable, highly condensed form of chromosomal material that appears in the cells of human beings and other eukaryotes. MBL scientists Michael Shribak (the microscope’s inventor) and Tomomi Tani, together with Kazuhiro Maeshima of the National Institute of Genetics, Japan, recently reported their findings in Molecular Biology of the Cell.