Regensburg 2010 – scientific programme
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BP: Fachverband Biologische Physik
BP 21: Neurobiophysics and Sensory Transduction
BP 21.9: Talk
Wednesday, March 24, 2010, 16:30–16:45, H43
Chromatin rearrangements transform mammalian photoreceptor nuclei into micro-lenses — •Moritz Kreysing1, Lars Boyde1, Kevin Chalut1, Irina Solovei2, Boris Joffe2, Leo Peichel3, Thomas Cremer2, and Jochen Guck1 — 1Cavendish Laboratory, University of Cambridge, UK — 2Institute for Human Genetics, LMU Munich, Germany — 3MPI for Brain Research, Frankfurt, Germany
The vertebrate retina is inverted with respect to its optical function. This means light needs to propagate through hundreds of microns of living neuronal tissue before it can be detected by the photoreceptor cells.
In this work we focus on the optical properties of the photoreceptor nuclei that are stored in multiple layers directly before the light sensitive segments. Based on micro-interferometry we show that a unique inversion of their spatial chromatin distribution in mammals with a nocturnal lifestyle transforms these nuclei into micro-lenses. Analytical models and finite difference time domain simulations suggest that the arrangement of these nuclei in columns greatly improves transmission characteristics by a reduction of scattering and an effective channeling of light through the outer nuclear layer.
These results change our understanding of the mammalian retina as an optical system. Furthermore, our findings indicate that the standard model of a nucleus with the heterochromatin located near the nuclear envelope is not the only solution to gene expression and regulation.