First identification and localization of a visual pigment in Hydra (Cnidaria, Hydrozoa)

• DOI: 10.1007/s003590100180
• Publication Date: 2003-02-13T03:25:53Z
• Authors: C. Musio; S. Santillo; C. Taddei-Ferretti; L.J. Robles; R. Vismara; L. Barsanti; P. Gualtieri
• Keywords: Lernaean Hydra; Hydrozoa

The cnidarian Hydra does not possess identified photoreceptive structures or specialized cells for light detection; nevertheless, it shows a marked photosensitivity. So far no evidence has been previously reported about the localization of the proteins involved in the photoresponse. We used polyclonal antibodies and immunofluorescence microscopy on whole-mount Hydra to identify a putative rhodopsin-like protein. Our results show an immunoreactivity in the ectodermal layer of Hydra, which corresponds in position to the nervous epidermal sensory cells. These data provide the first identification of a rhodopsin-like protein in a phylogenetically old invertebrate and give a new insight into the Hydra photoreceptive response.