May 13, 1998 FORT LAUDERDALE, Fla. -- Researchers have succeeded in introducing a gene that produces a human photopigment into laboratory mice, creating transgenic rodents that have the widest known spectral range of vision of any mammal.
Electrophysiological test indicates the pigment functions normally in the mice and the gene is transferable from one generation to another, according to the researchers from the University of Washington and the University of California, Santa Barbara.
Creation of the transgenic mice will give scientists a new vehicle for studying human vision problems, as well as a tool for investigating the evolution of sight and how the nervous system reacts to new sources of information, says Michael Crognale, a UW research assistant professor of psychology and Samir Deeb, a UW research professor of medical genetics.
Deeb will describe the characteristics of the new line of mice at the annual meeting of the Association for Research in Vision and Ophthalmology here, May 14. The research also was published last week in Investigative Ophthalmology and Visual Science.
Normal mice and humans both have visual spectral ranges that extend over about 300 nanometers. What the two species see, however, is different. The wild or laboratory mouse's vision stretches from the ultra-violet range, which humans can't see, up through medium wavelengths to yellow-green. Humans see in a spectrum that extends from violet to red.
Mice lack the photopigment or protein that allows them to see long-wave or red light. To expand the spectral range of mouse vision, the researchers introduced the gene that produces human L-photopigment (long wave) into mice embryos. The result is the line of mice that can see over a range of about 360 nanometers, more than humans or old world primates (apes and pack monkeys), which have the widest natural vision range of any mammal, says Crognale. Some birds, insects and fish have even wider vision ranges.
The researchers hope to use the mice to investigate a number of scientific questions. Crognale is interested in understanding how the transgenic mice are able to use information being gathered by the new photopigment.
"We are investigating how the nervous system reacts to new information," he explains. "We want to know how adaptable the neural system is. Does it allow an animal to immediately take advantage of the information or does it first have to develop specialized neural hardware or connections?"
"This relates to questions of human evolution and to understanding how neurons know how or what to connect to. In addition, we are interested in how a new capability or mutation like this is passed along. Some researchers have argued that for a mutation to be conserved it must confer some kind of benefit to the animal, or at least not cost the animal."
Deeb, meanwhile, will look at introducing mutations of the long-wave photopigment into mice to see if they modify cells in the animals' retinas and effect their vision.
Other members of the research team that contributed to developing the mice are Gerald Jacobs, a professor of psychology at the Neuroscience Research Institute at UCSB; Jing Huang, a technician at the UW Department of Ophthalmology; Salam Shaaban, UW post-doctoral researcher now in private industry, and Jack Calderone, a UCSB graduate student.
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