A mammalian clock protein responds directly to light

Jul 01, 2008

We all know that light effects the growth and development of plants, but what effect does light have on humans and animals? A new paper by Nathalie Hoang et al., published in PLoS Biology this week, explores this question by examining cryptochromes in flies, mice, and humans. In plants, cryptochromes are photoreceptor proteins which absorb and process blue light for functions such as growth, seedling development, and leaf and stem expansion.

Cryptochromes are present in humans and animals as well and have been proven to regulate the mechanisms of the circadian clock. But how they work in humans and animals is still somewhat of a mystery.

When plants are exposed to blue light, they experience a reduction in flavin pigments. This reduction activates the cryptochromes and thus allows for growth and seedling development. Hoang et al. sought to study the effect of blue light on fly, animal, and human cryptochromes by exposing them to blue light and measuring the change in the number of oxidized flavins. After a prolonged exposure to blue light, the authors found that the number of flavins did in fact decrease, as they do in plants.

While this research reveals a similarity in the responses of flies, mice, humans, and plants to blue light, the decrease in flavins affects circadian rhythms differently. The mouse cryptochromes, Mcry1 and Mcry2, interact with key parts of the circadian clock: mice with these cryptochromes missing exhibited a complete loss in circadian rhythm behaviors such as wheel-running. However, this change in behavior was independent of light exposure.

Although this paper by Hoang, et al, shows that cryptochromes in animals and humans do respond to light in a similar fashion to those in plants, the question as to how exactly light effects them is still open for further research. Although cryptochromes are mainly found in the retina of the eye, they are also present in many different tissues of the body that are close to the surface. This suggests that cryptochromes may have non-visual functions, and may also affect protein levels and behavior.

Citation: Hoang N, Schleicher E, Kacprzak S, Bouly JP, Picot M, et al. (2008) Human and Drosophila cryptochromes are light activated by flavin photoreduction in living cells. PLoS Biol 6(7): e160. doi:10.1371/journal.pbio.0060160 (biology.plosjournals.org/perls… journal.pbio.0060160)

Source: Public Library of Science

Explore further: Compact wool measurement tool may find home on the range

add to favorites email to friend print save as pdf

Related Stories

At the heart of the circadian clock

Jun 11, 2013

(Phys.org) —Cellular processes in most organisms are regulated by an internal clock, and proteins called cryptochromes are at the core of its central oscillator. The three dimensional structures of cryptochromes ...

Researchers find new light-sensing mechanism in neurons

Mar 03, 2011

A UC Irvine research team led by Todd C. Holmes has discovered a second form of phototransduction light sensing in cells that is derived from vitamin B2. This discovery may reveal new information about cellular ...

Recommended for you

Population genomics unveil seahorse domain

16 hours ago

In a finding vital to effective species management, a team including City College of New York biologists has determined that the lined seahorse (Hippocampus erectus) is more a permanent resident of the we ...

IBM and Mars join together to make food safer with genetics

18 hours ago

(Phys.org)—Computer giant IBM, and food giant Mars, have announced a joint project they are calling "Consortium for Sequencing the Food Supply Chain." The idea is to use modern microbiology, computer crunching ...

Researchers develop new potato cultivar

19 hours ago

Dakota Ruby is the name of a new potato cultivar developed by the NDSU potato breeding project and released by the North Dakota Agricultural Experiment Station. Dakota Ruby has bright red skin, stores well and is intended ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.