A cGMP-gated cation channel in depolarizing photoreceptors of the lizard parietal eye
Article Abstract:
Exposure to light causes the rods and cones of the two lateral eyes of vertebrates to hyperpolarize. This can be attributed to a cyclic GMP cascade that results in cGMP hydrolysis and the consequent closure of cGMP-gated cation channels that open in the dark. In contrast, the parietal or third eye of lizards and other lower vertebrates depolarize when illuminated. Despite these opposite reactions, evidence is found indicating that both lateral eyes and parietal eyes use a cGMP signalling cascade for phototransduction without the involvement of inositol-1,4,5-trisphosphate.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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Strange case of the third eye
Article Abstract:
Research on the eyes of lizards has resulted in an exception to the commonly held belief that all vertebrate photoreceptors hyperpolarize. The lizard parietal eye was found to have a primary light response that is depolarizing. The same photoreceptors also show a hyperpolarizing light response. Questions raised by these findings include the role of the phospholipase C in the depolarizing response of the eye, and the bistable nature of the photopigment found in the eye.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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Antagonistic chromatic mechanisms in photoreceptors of the parietal eye of lizards
Article Abstract:
Chromatic antagonism in the parietal eye of lizards originates in the chromatically dependant hyperpolarizing and depolarizing response of the photoreceptors to light. Unlike other vertebrate eyes, the third eye of the lizard does not contain interneurons, meaning that photoreceptors synapse directly into ganglion cells. Antagonistic chromatic mechanisms modulate the ganglion cell responses. This may be provide lizards with enhanced detection of dawn and dusk.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
User Contributions:
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