Featured Research

from universities, journals, and other organizations

To Arctic animals, time of day really doesn't matter

Date:
March 15, 2010
Source:
Cell Press
Summary:
In the far northern reaches of the Arctic, day versus night often doesn't mean a whole lot. During parts of the year, the sun does not set; at other times, it's just the opposite. A new study shows that Arctic reindeer have come up with a solution to living under those extreme conditions: They've abandoned use of the internal clock that drives the daily biological rhythms in other organisms.

Wild arctic reindeer in the wilderness of Svalbard islands, Norway.
Credit: iStockphoto/Laila Røberg

In the far northern reaches of the Arctic, day versus night often doesn't mean a whole lot. During parts of the year, the sun does not set; at other times, it's just the opposite. A new study reported online on March 11th in Current Biology, a Cell Press publication, shows that Arctic reindeer have come up with a solution to living under those extreme conditions: They've abandoned use of the internal clock that drives the daily biological rhythms in other organisms.

"Our findings imply that evolution has come up with a means of switching off the cellular clockwork," said Andrew Loudon of the University of Manchester. "Such daily clocks may be positively a hindrance in environments where there is no reliable light-dark cycle for much of the year."

Light-dark cycles drive hormone rhythms via a circuit that involves the eye and nervous system projections to structures involved in regulating hormone rhythms, in particular melatonin, Loudon explained. In most mammals, this wiring circuit also involves an internal clock that drives hormone levels in a rhythmic 24-hour fashion, even when there is no light-dark cycle.

"In reindeer, it is this clock element that seems to be missing," Loudon said. The reindeer show no natural internal rhythm of melatonin secretion at all. Instead, hormone levels rise and fall in direct response to light and dark. The researchers show that melatonin levels remain at or below detectable levels during daylight hours. Those hormone concentrations spike almost as soon as the light goes out, only to dive again when it switches back on.

Further studies by Loudon and his colleague Karl-Arne Stokkan of the University of Tromsø in Norway using reindeer skin cells showed that two well-known clock genes don't oscillate the way they do in other organisms as a way of keeping time. "We suspect that they have the full range of normal clock genes, but these are regulated in a different way in reindeer," Loudon said.

The researchers say that the findings initially came as a surprise, but they now suspect that similar patterns will be uncovered in other Arctic animals.

"Synchronization of seasonal cycles in mammals is a prominent feature of physiological adaptation in northern temperate and Arctic species," Loudon and Stokkan write. "Studies of seasonal sheep reveal that melatonin signals need only be present for a few weeks of the year to entrain an annual reproductive cycle. It is attractive to speculate that in reindeer, informative melatonin signals associated with equinoxes directly entrain a 'circannual clock' that, at least in reindeer, may not involve circadian mechanisms."

The researchers include Weiqun Lu, University of Manchester, Manchester, UK, Qing-Jun Meng, University of Manchester, Manchester, UK; Nicholas J.C. Tyler, University of Tromsø, Tromsø, Norway; Karl-Arne Stokkan, University of Tromsø, Tromsø, Norway; and Andrew S.I. Loudon, University of Manchester, Manchester, UK.


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Journal Reference:

  1. Weiqun Lu, Qing-Jun Meng, Nicholas J.C. Tyler, Karl-Arne Stokkan, and Andrew S.I. Loudon. A Circadian Clock Is Not Required in an Arctic Mammal. Current Biology, 2010; DOI: 10.1016/j.cub.2010.01.042

Cite This Page:

Cell Press. "To Arctic animals, time of day really doesn't matter." ScienceDaily. ScienceDaily, 15 March 2010. <www.sciencedaily.com/releases/2010/03/100311123516.htm>.
Cell Press. (2010, March 15). To Arctic animals, time of day really doesn't matter. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2010/03/100311123516.htm
Cell Press. "To Arctic animals, time of day really doesn't matter." ScienceDaily. www.sciencedaily.com/releases/2010/03/100311123516.htm (accessed April 18, 2014).

Share This



More Plants & Animals News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Vermont Goat Meat Gives Refugees Taste of Home

Vermont Goat Meat Gives Refugees Taste of Home

AP (Apr. 18, 2014) — Dairy farmers and ethnic groups in Vermont are both benefiting from a unique collaborative effort that's feeding a growing need for fresh and affordable goat meat. (April 18) Video provided by AP
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) — Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) — A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. Video provided by Newsy
Powered by NewsLook.com
The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) — Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins