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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/25524

Title: Rod-like Properties of Small Single Cones: Transmutated Photoreceptors of Garter Snakes (Thamnophis proximus)
Authors: Yang, Guang Yu Clement
Advisor: Chang, Belinda
Department: Cell and Systems Biology
Keywords: rhodopsin
garter snake
electron miscroscopy
in vitro expression
Issue Date: 31-Dec-2010
Abstract: While nocturnal basal snakes have rod-dominant retinae, diurnal garter snakes have all-cone retinae. Previous work from the Chang lab identified three visual pigments expressed in the photoreceptors of Thamnophis proximus: SWS1, LWS and RH1. I further characterized T. proximus photoreceptors using electron microscopy, immunohistochemistry, and in vitro protein expression. T. proximus have four types of morphological cones: double cones, large single cones, small single cones, and very small single cones. Some small single cones have rod-like features, such as rod-like outer-segment membranes and a lack of micro-droplets. Immunohistochemistry showed that rod-specific transducin is expressed in some T. proximus photoreceptors. In vitro expression of T. proximus RH1 produced a functional rhodopsin with λmax at 485nm, which corresponds to microspectrophotometry measurement from some small single cones. Current results suggest that small single cones of T. proximus may have evolved from ancestral rods, and secondarily acquired a cone-like morphology as adaptation to diurnality.
URI: http://hdl.handle.net/1807/25524
Appears in Collections:Master
Department of Cell and Systems Biology - Master theses

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