Navigation Links
Making mice with enhanced color vision

Researchers at the Johns Hopkins School of Medicine and their colleagues have found that mice simply expressing a human light receptor in addition to their own can acquire new color vision, a sign that the brain can adapt far more rapidly to new sensory information than anticipated.

This work, appearing March 23 in Science, also suggests that when the first ancestral primate inherited a new type of photoreceptor more than 40 million years ago, it probably experienced immediate color enhancement, which may have allowed this trait to spread quickly.

"If you gave mice a new sensory input at the front end, could their brains learn to make use of the extra data at the back end?" asks Jeremy Nathans M.D., Ph.D., professor of molecular biology and genetics, neuroscience, and ophthalmology at Hopkins. "The answer is, remarkably, yes. They did not require additional generations to evolve new sight."

Retinas of primates such as humans and monkeys are unique among mammals in that they have three visual receptors that absorb short (blue), medium (green) and long (red) wavelengths of light. Mice, like other mammals, only have two; one for short and one for medium wavelengths.

In the study, the researchers designed a "knock-in" mouse that has one copy of its medium wavelength receptor replaced with the human long wavelength receptor, so both were expressed in the retina. The human receptors were biologically functional in the mice, but the real question was whether the mice could use the new visual information.

To address this question, the researchers used a classic preference test; mice set before three light panels were trained to touch the one panel that appeared to differ from the other two. A correct answer was rewarded with a drop of soy milk.

To circumvent thorny issues related to the subjective nature of color perception -- everyone who has had a discussion as to whether the "green" they see is the same as t he "green" their friend sees can attest to this -- the researchers only tested whether the mice could discriminate among the lights.

"Each photoreceptor absorbs a range of wavelengths, but the efficiency changes with wavelength," Nathans explains. "For example, one photoreceptor might absorb green light only half as efficiently as red light. If an animal had only this type of photoreceptor, then a green light that was twice as bright as a red light would look identical to the red one. But if the animal adds a second photoreceptor with different absorption properties, then by comparing both receptors, the red and green lights could always be distinguished."

Normal mice failed to discriminate yellow versus red lights when the light intensities were set to give equal activation of their middle wavelength receptor. However, mice with both the human long wavelength and the mouse middle wavelength receptors learned to tell the difference, although it took over 10,000 trials to learn to make the distinction.

Nathans suggests that these knock-in mice mimic how our earliest primate ancestors acquired trichromatic vision, color vision based on three receptors. At some point in the past, random mutations created a variant of one receptor gene, located on the X chromosome, producing two different receptor types. Present-day New World (South American) monkeys still use this system, which means that in these monkeys only certain females can acquire trichromatic color vision.

In contrast, among Old World (African) primates such as humans, the two different X chromosome genes duplicated so that each X chromosome now carries the genes for both receptor types, giving both males and females trichromatic color vision.

"You could say that the original primate color vision system, and the one that New World monkeys still use today, is the poor man's -- or to be accurate, poor woman's -- version of color vision," Nathans says.


'"/>

Source:Johns Hopkins Medical Institutions


Related biology news :

1. Making Sure Sacred Sheep Dont Become Extinct
2. Muscle repair: Making a good system better, faster; implications for aging, disease
3. Making plant cells work like miniature factories
4. Making medicine smarter
5. Making a face: A new and earlier marker of neural crest development
6. Mouse with designer liver has enhanced glucose tolerance, insulin response
7. Study finds that nutritionally enhanced rice reduces iron deficiency
8. Researchers report technique for freezing and preserving genetically enhanced pig embryos
9. Fish growth changes enhanced by climate change
10. Scientists genetically engineer tomatoes with enhanced folate content
11. ASU researchers finds novel chemistry at work to provide parrots vibrant red colors
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:7/20/2017)... -- Delta (NYSE: DAL ) customers now can use fingerprints ... Washington National Airport (DCA). ... Delta launches biometrics to board aircraft at Reagan Washington National ... Delta,s biometric boarding pass experience that launched ... into the boarding process to allow eligible Delta SkyMiles Members who are ...
(Date:5/16/2017)... -- Veratad Technologies, LLC ( www.veratad.com ), an innovative and ... solutions, announced today they will participate as a sponsor ... May 17, 2017, in Washington D.C.,s ... Identity impacts the lives of billions of ... digital world, defining identity is critical to nearly every ...
(Date:4/18/2017)... 2017  Socionext Inc., a global expert in SoC-based imaging and ... the M820, which features the company,s hybrid codec technology. A demonstration ... Probe, Inc., will be showcased during the upcoming Medtec Japan at ... the Las Vegas Convention Center April 24-27. ... Click here for an ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... October 12, 2017 , ... DuPont Pioneer ... that they have entered into a multiyear collaboration to identify and characterize novel ... additional tools for gene editing across all applications. , Under the terms of ...
(Date:10/11/2017)... Charlotte, N.C. (PRWEB) , ... October 11, 2017 ... ... ARCS® Foundation President Andi Purple announced Dr. Suneel I. Sheikh, the ... Laboratories ( ASTER Labs ), Inc. has been selected for membership in ...
(Date:10/11/2017)... Oct. 11, 2017  VMS BioMarketing, a leading provider of ... oncology Clinical Nurse Educator (CNE) network, which will launch this ... communication among health care professionals to enhance the patient care ... staff, and other health care professionals to help women who ... ...
(Date:10/10/2017)... ... ... San Diego-based team building and cooking events company, Lajollacooks4u, has unveiled a ... new look is part of a transformation to increase awareness, appeal to new markets ... It will also expand its service offering from its signature gourmet cooking classes and ...
Breaking Biology Technology: