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DNA ribbons


© F. Livolant/CNRS Photothèque


Don't be mistaken, you're not looking through a kaleidoscope, but through a polarizing microscope. This iridescent ribbon is made of aligned DNA molecules arranged locally in a hexagonal network. In this liquid crystal, the orientation of molecules may vary, giving this image of undulations. The blue colours of birefringence come from the DNA ordering. A totally disorganized sample would appear black. Françoise Livolant, from the Laboratory of Physics of Solids,1 obtained these images by dissolving short DNA fragments (150 bp) in a buffered solution, at concentrations comparable to those found in a bacteriophage capsid, or in the head of some spermatozoids (i.e., around 500 mg/ml). Analysis of the textures of the sample allows researchers to better understand how DNA is organized in crowded conditions, in conditions of viscosity close to its natural environment.


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Notes :

1. Laboratoire de Physique des solides (CNRS / Université Paris XI joint lab).
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Contacts :

Françoise Livolant,


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