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DERIVED PHOTOSENSITIVE PIGMENTS FROM INVERTEBRATE EYES
1Laboratory of Biophysics, Columbia University, New York.
The Journal of General Physiology
|October 30, 2009
Summary
Formalin treatment makes crustacean and cephalopod eye pigments photosensitive, revealing a blue-green absorption spectrum. This suggests the light sensitivity of squid photopigments may not depend on their light stability.
Area of Science:
- Biochemistry
- Vision Science
- Marine Biology
Background:
- The visual pigments in marine invertebrates like squid, blue crabs, and horseshoe crabs are crucial for their vision.
- Understanding the properties of these pigments can offer insights into visual mechanisms across different species.
Purpose of the Study:
- To investigate the photosensitivity and spectral properties of red eye pigments from squid, blue crab, and horseshoe crab after formalin treatment.
- To compare the spectral characteristics of the treated pigment with the spectral sensitivity of cephalopod eyes and vertebrate visual purple.
- To explore the relationship between light sensitivity and light stability in normal squid photopigments.
Main Methods:
- Treatment of eye pigments from squid, blue crab, and horseshoe crab with formalin.
- Irradiation of the treated pigment and measurement of density changes.
- Spectrophotometric analysis to determine the difference absorption spectrum.
- Identification of breakdown products, such as retinene, upon bleaching.
Main Results:
- Formalin treatment induced photosensitivity in the red pigments, causing them to bleach in light.
- The resulting difference absorption spectrum showed a maximum around 480 nm (blue-green).
- The spectral properties were similar to cephalopod eye sensitivity and vertebrate visual purple.
- Bleaching of the formalin-sensitized pigment in squid retinas released significant amounts of retinene.
- The pigment was determined not to be melanoid.
Conclusions:
- The formalin-sensitized pigment exhibits spectral properties consistent with visual pigments.
- The release of retinene upon bleaching indicates a role in the visual cycle.
- It is proposed that the light sensitivity of the native squid photopigment might be independent of its light stability.
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