One of the big fundamental questions tackled within EuroDYNA concerned the detailed structure of how the DNA double helix is folded in the nucleus of higher organisms. Although the double helix structure was discovered by Crick and Watson in 1953, the way it folds and stretches such that it fits in the cell nucleus is only now becoming clear, as is its relevance both for cell replication and gene expression. At the EuroDYNA conference, John van Noort from Leiden University in the Netherlands reported that the DNA molecule, which in humans and most mammals is about two metres in length but only 2 nanometres in diameter, is coiled up like a spring in a solenoid structure. In such a folded structure it behaves according to the well known Hooke's law, stating that up to a certain point the extension is proportional to the force applied. It turns out chromatin is a very elastic molecular complex, capable of stretching to three times its normal rest length without breaking, according to van Noort. Even more remarkably and here it differs from a familiar metal spring - even if stretched beyond three times its rest length, the chromatin solenoid is capable of repairing itself and regaining its former shape and elasticity.
Indeed the ability of DNA to repair itself is essential for the long term survival of the cell and ultimately of the whole organism. DNA damage occurs not just from factors outside the cell nucleus, but also during the process of cell division (mitosis). The overall objective is to hand down the correct genetic code to the daughter cells during mitosis, a process so important that a number of surveillance and repair systems have been put in place to ensure its completion. One of those systems is called PRR (Post Replicative Repair) and it is highly conserved among all organi
|Contact: Astrid Lunkes|
European Science Foundation