Behavior of Rhodopsin and Metarhodopsin in Isolated Rhabdoms of Crabs and Lobster
The photoreceptor organelles — the rhabdoms — of decapod Crustacea are elongate structures consisting of interleaved layers of microvilli from seven or eight retinular cells (1,2,3). When the eyes are broken open in an appropriate saline, the rhabdoms detach from the surrounding retinular cells, and individual rhabdoms can be identified under the microscope and studied spectrophotometrically with laterally-incident microbeams. All of the spectrophotometric measurements of rhabdoms described in this communication were performed on an instrument similar to that of Liebman and Entine (4). We have examined freshly-isolated rhabdoms as well as organelles fixed in 5% glutaraldehyde. The original reason for introducing glutaraldehyde fixation was to stabilize the structure of the isolated rhabdoms for periods commensurate with the measurements of pigment we wish to make (5). Although glutaraldehyde does not alter the absorption spectrum of either rhodopsin or metarhodopsin, it can hasten the destruction of both pigments, and therefore it is a useful tool in analyzing the pigment composition of rhabdoms by means of difference spectra.
KeywordsDifference Spectrum Blue Crab Visual Pigment Green Crab Retinular Cell
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