Recoverin Does Not Influence the Threshold for Cone-Mediated Vision in Mice

Abstract

Purpose:: To determine if recoverin affects cone-mediated vision in mice. In previous studies we showed that recoverin deficiency (Rv-/-) raises the threshold for scotopic vision of mice in a water maze by 4X. Recoverin is expressed from the same gene in both rods and cones. We used mice in which vision is mediated only by cones to evaluate the influence of recoverin on cone-mediated vision.

Methods:: We used a previously described method, a water maze, to evaluate the ability of mice to visually discriminate a black wall from 5 white walls^1,2. All experiments were done using mice with a deficiency of rod transducin (GNAT1-/-). (GNAT1-/- mice were produced by Janis Lem and colleagues). By varying the intensity of illumination of the water maze we determined the visual thresholds of GNAT1-/- mice and GNAT1-/-;Rv-/- mice. (Rv-/- mice were produced by Jeannie Chen and colleagues). We also compared the sensitivities of ERG b-waves from GNAT1-/- mice with GNAT1-/-;Rv-/- mice.

Results:: The visual thresholds in dim light for GNAT1-/- mice and GNAT1-/-;Rv-/- mice were indistinguishable. Consistent with this, the sensitivity of the ERG b-wave for GNAT1-/- and GNAT1-/-;Rv-/- mice were also indistinguishable. The kinetics of b-wave responses from both strains also were indistinguishable.

Conclusions:: Recoverin does not affect the threshold for cone-mediated vision in dim light in mice. Additional studies will be done to determine if recoverin affects cone-mediated vision at higher levels of illumination. ¹Hayes, J.M. and Balkema, G.W. (1993). Behav. Genet. 23:395 ²Nathan et al. (2006). Photochem. Photobiol. (Epub ahead of print)

Keywords: photoreceptors: visual performance • photoreceptors