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: PacifiCorp Energy pleads guilty in bird deaths

add to favorites email to friend print save as pdf

Related Stories

People finding their 'waze' to once-hidden streets

1 hour ago

When the people whose houses hug the narrow warren of streets paralleling the busiest urban freeway in America began to see bumper-to-bumper traffic crawling by their homes a year or so ago, they were baffled.

Identity theft victims face months of hassle

1 hour ago

As soon as Mark Kim found out his personal information was compromised in a data breach at Target last year, the 36-year-old tech worker signed up for the retailer's free credit monitoring offer so he would ...

Observers slam 'lackluster' Lima climate deal

2 hours ago

A carbon-curbing deal struck in Lima on Sunday was a watered-down compromise where national intransigence threatened the goal of a pact to save Earth's climate system, green groups said.

Your info has been hacked. Now what do you do?

2 hours ago

Criminals stole personal information from tens of millions of Americans in data breaches this past year. Of those affected, one in three may become victims of identity theft, according to research firm Javelin. ...

New Bond script stolen in Sony hack

2 hours ago

An "early version" of the screenplay for the new James Bond film was the latest victim of a massive hacking attack on Sony Pictures Entertainment, its producers said in a statement on their website Sunday.

Ag-tech could change how the world eats

7 hours ago

Investors and entrepreneurs behind some of the world's newest industries have started to put their money and tech talents into farming - the world's oldest industry - with an audacious agenda: to make sure there is enough ...

Recommended for you

A vegetarian carnivorous plant

22 hours ago

Carnivorous plants catch and digest tiny animals in order and derive benefits for their nutrition. Interestingly the trend towards vegetarianism seems to overcome carnivorous plants as well. The aquatic carnivorous bladderwort, ...

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.