Genetically engineered mice with an additional class of cone photoreceptors: Implications for the evolution of color vision

Philip M. Smallwood, Bence P. Ölveczky, Gary L. Williams, Gerald H. Jacobs, Benjamin E. Reese, Markus Meister, Jeremy Nathans

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


Among eutherian mammals, only primates possess trichromatic color vision. In Old World primates, trichromacy was made possible by a visual pigment gene duplication. In most New World primates, trichromacy is based on polymorphic variation in a single X-linked gene that produces, by random X inactivation, a patchy mosaic of spectrally distinct cone photoreceptors in heterozygous females. In the present work, we have modeled the latter strategy in a nonprimate by replacing the X-linked mouse green pigment gene with one encoding the human red pigment. In the mouse retina, the human red pigment seems to function normally, and heterozygous female mice express the human red and mouse green pigments at levels that vary between animals. Multielectrode array recordings from heterozygous female retinas reveal significant variation in the chromatic sensitivities of retinal ganglion cells. The data are consistent with a model in which these retinal ganglion cells draw their inputs indiscriminately from a coarse-grained mosaic of red and green cones. These observations support the ideas that (i) chromatic signals could arise from stochastic variation in inputs drawn nonselectively from red and green cones and (ii) tissue mosaicism due to X chromosome inactivation could be one mechanism for driving the evolution of CNS diversity.

Original languageEnglish (US)
Pages (from-to)11706-11711
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number20
StatePublished - Sep 30 2003


  • Cone visual pigments
  • Mouse genetics
  • Retinal ganglion cells
  • Trichromacy

ASJC Scopus subject areas

  • General


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