From Medical Xpress:

Neuropsin (in blue) was found in nerve cells in the retina of a genetically engineered mouse. Credit: Wendy Yue, Johns Hopkins Medicine

Researchers at Johns Hopkins and the University of Washington report new research that sheds light on how the retina sets its own biological rhythm using a novel light-sensitive pigment, called neuropsin, found in nerve cells at the back of the eye.

“No one knew what neuropsin actually did,” says King-Wai Yau, Ph.D., a professor of neuroscience at Johns Hopkins School of Medicine. “We only knew it existed in the mammalian genome and may help set the timing of reproduction for some birds. Now we think we know what it does in mammals.” The new study, described in a report online on Sept. 21 of the journal Proceedings of the National Academy of Sciences, ushers in a more complex view of the retina, according to Zheng Jiang, Ph.D., a postdoctoral fellow and one of the authors of the paper.

Neuropsin is one of seven related “opsin” proteins in mammals. Four enable the rod and cone cells of the retina to absorb light of different wavelengths and transmit that information to the brain so that the eye can see images. Another opsin, melanopsin, also absorbs light but uses it to guide processes like pupil constriction and . It is found in that connect the retina to the body’s , the suprachiasmatic nuclei of the brain. On its own, this master clock tends to run…

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