Emergence of Novel Color Vision in Mice Engineered to Express a Human Cone Photopigment

Neuroscience Research Institute and Department of Psychology, University of California, Santa Barbara, CA 93106, USA.
Science (Impact Factor: 33.61). 04/2007; 315(5819):1723-5. DOI: 10.1126/science.1138838
Source: PubMed

ABSTRACT Changes in the genes encoding sensory receptor proteins are an essential step in the evolution of new sensory capacities. In primates, trichromatic color vision evolved after changes in X chromosome-linked photopigment genes. To model this process, we studied knock-in mice that expressed a human long-wavelength-sensitive (L) cone photopigment in the form of an X-linked polymorphism. Behavioral tests demonstrated that heterozygous females, whose retinas contained both native mouse pigments and human L pigment, showed enhanced long-wavelength sensitivity and acquired a new capacity for chromatic discrimination. An inherent plasticity in the mammalian visual system thus permits the emergence of a new dimension of sensory experience based solely on gene-driven changes in receptor organization.

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    • "Such adaptability and plasticity of the brain will make the knock-in mice understand the world deeper than other mice. The above experiment in [5] inspires us a very interesting and challenging problem: can we exploit a computational model that is able to expand its cognitive dimension online freely? If this is achieved, the agent with such computational model will be able to expand its sensing capability during its lifetime. "
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    ABSTRACT: The proposed perception evolution network (PEN) is a biologically inspired neural network model for unsupervised learning and online incremental learning. It is able to automatically learn suitable prototypes from learning data in an incremental way, and it does not require the predefined prototype number or the predefined similarity threshold. Meanwhile, being more advanced than the existing unsupervised neural network model, PEN permits the emergence of a new dimension of perception in the perception field of the network. When a new dimension of perception is introduced, PEN is able to integrate the new dimensional sensory inputs with the learned prototypes, i.e., the prototypes are mapped to a high-dimensional space, which consists of both the original dimension and the new dimension of the sensory inputs. In the experiment, artificial data and real-world data are used to test the proposed PEN, and the results show that PEN can work effectively.
    IEEE transactions on neural networks and learning systems 04/2015; DOI:10.1109/TNNLS.2015.2416353 · 4.29 Impact Factor
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    • "Although two distinct opsins is the norm in Pteropus (Wang et al. 2004; Müller et al. 2007; Zhao et al. 2009a), trichromatic vision is plausible in P. samoensis for two reasons: first, the visual system of Pteropodidae is strikingly similar to that of primates (Pettigrew 1986, 1995; Fig. 2), suggesting that P. samoensis has the neural preadaptations to support trichromatic vision. Such homoplasy is not strictly necessary, however, as the engineering of trichromatic mice demonstrates (Jacobs et al. 2007). Second, duplication of the long wavelength-sensitive (LWS) opsin gene is documented in at least one pteropodid species, Haplonycteris fischeri (Wang et al. 2004). "
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    ABSTRACT: A nocturnal bottleneck during mammalian evolution left a majority of species with two cone opsins, or dichromatic color vision. Primate trichromatic vision arose from the duplication and divergence of an X-linked opsin gene, and is long attributed to tandem shifts from nocturnality to diurnality and from insectivory to frugivory. Opsin gene variation and at least one duplication event exist in the order Chiroptera, suggesting that trichromatic vision could evolve under favorable ecological conditions. The natural history of the Samoan flying fox (Pteropus samoensis) meets these conditions-it is a large bat that consumes nectar and fruit and demonstrates strong diurnal proclivities. It also possesses a visual system that is strikingly similar to that of primates. To explore the potential for opsin gene duplication and divergence in this species, we sequenced the opsin genes of 11 individuals (19 X-chromosomes) from three South Pacific islands. Our results indicate the uniform presence of two opsins with predicted peak sensitivities of ca. 360 and 553 nm. This result fails to support a causal link between diurnal frugivory and trichromatic vision, although it remains plausible that the diurnal activities of P. samoensis have insufficient antiquity to favor opsin gene renovation.
    Journal of Comparative Physiology 10/2014; DOI:10.1007/s00359-014-0951-x · 2.04 Impact Factor
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    • "keys, and some of the heterozygous mice gained red-green color vision capacities (Jacobs et al. 2007). Interestingly, red-green color vision in the mice was very weak compared with that shown by humans with normal trichromacy or by the monkeys treated with gene therapy; it was so weak, in fact, that it was not detected in two of the five mice tested. "
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    ABSTRACT: It has been possible to use viral-mediated gene therapy to transform dichromatic (red-green color-blind) primates to trichromatic. Even though the third cone type was added after the end of developmental critical periods, treated animals acquired red-green color vision. What happened in the treated animals may represent a recapitulation of the evolution of trichromacy, which seems to have evolved with the acquisition of a third cone type without the need for subsequent modification to the circuitry. Some transgenic mice in which a third cone type was added also acquired trichromacy. However, compared with treated primates, red-green color vision in mice is poor, indicating large differences between mice and monkeys in their ability to take advantage of the new input. These results have implications for understanding the limits and opportunities for using gene therapy to treat vision disorders caused by defects in cone function.
    Cold Spring Harbor Perspectives in Medicine 08/2014; 4(11). DOI:10.1101/cshperspect.a017418 · 9.47 Impact Factor
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