Related Experiment Video
Updated: May 11, 2026

Determination of Photoreceptor Cell Spectral Sensitivity in an Insect Model from In Vivo Intracellular Recordings
Published on: February 26, 2016
C-opsin expressing photoreceptors in echinoderms
Esther M Ullrich-Lüter1, Salvatore D'Aniello, Maria I Arnone
1Universität Bonn, Institut für Evolutionsbiologie und Ökologie, An der Immenburg 1, 53121 Bonn, Germany.
Abstract:
Today's progress in molecular analysis and, in particular, the increased availability of genome sequences have enabled us to investigate photoreceptor cells (PRCs) in organisms that were formerly inaccessible to experimental manipulation. Our studies of marine non-chordate deuterostomes thus aim to bridge a gap of knowledge regarding the evolution of deuterostome PRCs prior to the emergence of vertebrates' eyes. In this contribution, we will show evidence for expression of a c-opsin photopigment, which, according to our phylogenetic analysis, is closely related to an assemblage of chordate visual c-opsins. An antibody raised against sea urchins' c-opsin protein (Sp-Opsin1) recognizes epitopes in a variety of tissues of different echinoderms. While in sea urchins this c-opsin is expressed in locomotory and buccal tube feet, spines, pedicellaria, and epidermis, in brittlestars and starfish we found the immuno-reaction to be located exclusively in cells within the animals' spines. Structural characteristics of these c-opsin+ PRC types include the close vicinity/connection to nerve strands and a, so far unexplored, conspicuous association with the animals' calcite skeleton, which previously has been hypothesized to play a role in echinoderm photobiology. These features are discussed within the context of the evolution of photoreceptors in echinoderms and in deuterostomes generally.
Related Concept Videos
Channel Rhodopsins
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Photoreceptors and Visual Pathways
Anatomy of the Eyeball
The Retina
G-Protein Gated Ion Channels
Sensory organs,...
Unrenewable Cells
Photoreceptors
The retina is composed of several layers and contains specialized cells called photoreceptors. The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy. There are two types of photoreceptors—rods and cones—which differ in the shape of their outer...

