Visual Neuroscience

Table of Contents - 1993 - Volume 10, Issue 04  

Research Articles

Visual pigments in the sea lamprey, Petromyzon marinus

Ferenc I. Hárosia1 and Jochen Kleinschmidta2

a1 Laboratory of Sensory Physiology, Marine Biological Laboratory, Woods Hole, and Department of Physiology, Boston University School of Medicine, Boston

a2 Department of Ophthalmology, New York University Medical Center, New York

Abstract

We present microspectrophotometric evidence for the existence of two distinct visual pigments residing in two different morphological types of photoreceptor of the sea lamprey. In the upstream migrant Petromyzon marinus, the pigment found in short receptors has a wavelength of peak absorbance (λmax) of 525 nm, whereas the pigment located in long receptors has a λmax of 600 nm. Although the former appears to be pure porphyropsin, the latter is akin to visual pigments found in the red-absorbing cones of amphibian and teleost retinae. The kinship is more than superficial pertaining to λmax of the a–band absorbance to its native maximum value. The presence of an anion-sensitive and an anion-insensitive pigment in a retina implies the expression of two distinct opsin genes. We infer this from several examples of correlation between anion sensitivity and opsin sequence groupings. Moreover, the presence of two distinct opsin genes expressed throughout six vertebrate classes implies their existence in a common ancestor to all.

(Received October 23 1992)

(Accepted December 22 1992)

Keywords

Footnotes

Reprint requests to: Ferenc I. Hárosi, Marine Biological Laboratory, Woods Hole, MA 02543, USA.