Chromosome lifetime map

David Lleres, University of Dundee

Browse Wellcome Images for others like this

Download this image from Wellcome Images

Image of a human chromosome in metaphase created by fluorescence lifetime imaging microscopy/Förster resonance energy transfer (FLIM/FRET). The colours in this image indicate the density of chromatin in the chromosome, like a heat map (red shows high density, blue low). A low density of chromatin indicates a high level of gene expression, and a high density indicates repression of gene expression.

What is chromatin?

Chromatin is the combination of DNA and proteins that results in the tight coiling of the DNA helix. Chromatin formation is important to ensure the long DNA molecule becomes sufficiently packed to fit into the cell nucleus.

Chromatin prevents DNA being damaged during cell division, or mitosis. In the metaphase stage of mitosis, chromatin packs DNA into the characteristic shape of chromosomes shown here. In the next stage, anaphase, the chromosomes are pulled apart and ultimately the cell divides. This structure is very strong, and prevents damage when the chromosomes are pulled apart.

Researchers are using the FLIM/FRET technique to better study chromatin and chromosome structure. It may help to understand why cells behave and respond differently to anticancer drug treatment and why cells do not divide properly.

Why did the judges like this image?

Adam Rutherford, editor at 'Nature' and presenter of BBC 4's 'Genome', explains: "In the ten years since the Human Genome Project revealed that we had fewer than 23 000 genes, geneticists have been exploring the mystery of what the other 97 per cent of the human genome is for. This beautiful chromosome shows how the overall structure of a genome is dynamically arranged, and how the density of chromatin is variable. This type of picture helps to reveal that large areas of the genome are active, and not the 'junk DNA' that they were once called."