Individual cells divide through a process called mitosis, during which the cell's copied DNA is separated between two resulting daughter cells. Despite recent advances in cell biology, the mechanism by which DNA condenses during mitosis is still poorly understood. Researchers recently tracked small stretches of DNA wound around histone proteins, called nucleosomes, to better characterize nucleosome behavior during cell division.
DNA is organized as chromatin, which are dynamic structures comprised of DNA, RNA, and proteins that regulate the accessibility of genes for expression and the overall configuration of genetic material in the cell. Histone proteins, for example, are positively charged proteins that bind to negatively charged DNA. DNA wraps around these histone proteins to form nucleosomes, which help condense nearly six feet of human genomic DNA into a nucleus only 10 micrometers (1 x 10 -6 m) across.
During mitosis, DNA condenses before being divided between two daughter cells. A protein complex called condensins is involved in assembling the condensed chromosomes. However, researchers are still unsure how cells achieve chromosome assembly during cell division.
To address this, a team of researchers from the National Institute of Genetics in Mishima, Japan, part of the Research Organization of Information and Systems (ROIS), used single-nucleosome imaging to reveal the factors that contribute to the organization and compaction of chromosomes during mitosis in living .