Mechanisms of Light Adaptation in Photoreceptor Cells: Phototransduction Protein and Ion Trafficking Between the Functional Compartments of Rods

Principal investigator: ARI KOSKELAINEN
Researcher: Elina Sahala

Laboratory of Biomedical Engineering, Helsinki University of Technology

The vertebrate visual system can operate over a wide range of light intensities, covering more than ten orders of magnitude. The dark-adapted photoreceptors, however, have limited dynamic ranges of operation, covering only about two log units for both rods and cones. Therefore, to avoid output signal saturation Nature has supplied the photoreceptor cells with several feedback mechanisms to control the gain of the phototransduction cascade (a process known as light adaptation).

This project is aimed at clarifying novel molecular mechanisms of light adaptation in vertebrate photoreceptors in a quantitative way, and constructing a new quantitative model for photoresponses at different mean illuminations. Our approach is to measure phototransduction protein and ion (calcium and hydrogen) movements between the two functional compartments of rods, the outer and the inner segment, by two-photon confocal laser scanning microscopy combined with electrophysiology.

Contact: ari.koskelainen(at)tkk.fi, tel. +358 9 451 3177