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DNA ribbons

amazing

© 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.

 

I. T.

 

 

Notes :

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

Françoise Livolant, livolant@lps.u-psud.fr


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