Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 41: Protein structure and dynamics I

BP 41.10: Talk

Thursday, March 19, 2015, 12:30–12:45, H 1058

Refractive index regulation of the vertebrate retina. — •Alfonso Garcia-Ulloa, Heike Petzold, Alexandr Dibrov, Kaushikaram Subramanian, and Moritz Kreysing — Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany

Due to its similarity, the vertebrate retina serves as a model system for the brain, and yet it is different. Whereas brain tissue is opaque on sub-millimeter scale, the retina is of high optical quality and manages to suppress the backscattering of photons on their way to the sensitive photoreceptors.

Although the molecular basis of the retina's optical quality is largely unknown so far, physical optics clearly states that the magnitude of scattering at given particle sizes mostly depends on the refractive index contrast. Also, it has been noted that phase contrast based microscopy technique yields small signals when applied to retinal tissues. These observations raise the question of what regulates the retinal refractive index distribution.

We hypothesize that proteins with housekeeping functions, highly soluble and with high weight-specific refractive indices fulfill the role of refractive index regulators in the retina. In mouse models, the expression of crystallins has been localized in regions of high refractive index contrast like the nuclei, in the inner nuclear layer and in between nuclei, in the outer nuclear layer.

Our study establishes the role of refractive index regulators in specific retinal layers by combining fluorescent localization, quantitative phase-contrast microscopy and quantitative mass spectrometry.