University of California researchers at Irvine reveal how an ancient flavoprotein response to ultraviolet (UV), blue, and red light informs internal circadian processes over the time of day.
The study, led by Todd C. Holmes, Ph.D., Professor at the Faculty of Physiology and Biophysics of the UCI School of Medicine, is titled "Various mechanisms of Drosophila CRYPTOCHROME-mediated photoreceptive membrane depolarization and in vivo clock reset" and was published in Proceedings of the National Academy of Sciences .
Phototransduction is relatively well characterized in the eyes and other external photoreceptors of animals for imaging vision. Much less understood are phototransduction mechanisms in non-eye-sensitive cells, including central brain neurons. In the study conducted by the UCI School of Medicine, researchers showed how blue and ultraviolet light (UV) produces a persistent light response that is critical to a form of non-imaging vision in which the ambient light values are averaged and reported to determine the time of day internal circadian processes. Red light causes a light reaction that does not last much longer.
"Imaging works so fast that humans, and probably other animals, perceive the visual world as a continuous process," said Holmes. "Our eyes capture moment-to-moment changes in the light that allow us to see objects and movements, even moving from a light to a dark environment, a very different kind of vision, the non-imaging vision, It's important to inform us about the time of day, based on the color and intensity of light.It's a slower visual process that captures an average of light levels rather than moment-to-moment changes in light. "That discovered that was not imaging See invertebrates based on the redox chemistry of a photosensitive protein called Cryptochrome. Biochemical redox chemistry is typically associated with metabolism.
"The protein ancestors of cryptochromes were ultraviolet-activated DNA repair enzymes that evolved more than 3 billion years ago, before the advent of our present oxygen-rich atmosphere, which protects us from harmful ultraviolet radiation. These first light-detecting mechanisms evolved When single cell organisms developed the ability to repair their UV-damaged DNA after they got too close to the water surface, this ancient form of non-imaging vision persists to this day. "
Light is the primary regulator of circadian rhythms and evokes a wide range of daytime behaviors. By better understanding the response of insects to short-wave light, researchers hope to find new, green alternatives to combat harmful insects, such as mosquitoes and flies, and reduce the need for toxic pesticides.
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Lisa S. Baik et al., "Different Mechanisms of CRYPTOCHROME-mediated Light-Directed Membrane Dolarization of Drosophila and In-vivo Reset of the Clock, Proceedings of the National Academy of Sciences (201
Study reveals non-imaging light-sensing mechanism of circadian neurons (2019, 7 November)
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