Featured Research

from universities, journals, and other organizations

Symbiotic bacteria program circadian-like rhythms in squid using light and chemicals

Date:
April 2, 2013
Source:
American Society for Microbiology
Summary:
Glowing bacteria inside squid use light and chemical signals to control circadian-like rhythms in the animals, according to a new study. The results of the study show that, in addition to acting as a built-in lamp, the bacteria also control when the squid expresses a gene that entrains, or synchronizes, circadian rhythms in animals.

Glowing bacteria inside squids use light and chemical signals to control circadian-like rhythms in the animals, according to a study to be published on April 2 in mBioฎ, the online open-access journal of the American Society for Microbiology.

The Hawaiian bobtail squid, Euprymna scolopes, houses a colony of Vibrio fischeri bacteria in its light organ, using the bacteria at night as an antipredatory camouflage while it ventures out to hunt. The results of the study show that, in addition to acting as a built-in lamp, the bacteria also control when the squid expresses a gene that entrains, or synchronizes, circadian rhythms in animals.

"To our knowledge, this is the first report of bacteria entraining the daily rhythms of host tissues," says corresponding author Margaret McFall-Ngai of the University of Wisconsin -- Madison. If bacteria can entrain daily rhythms in an animal, McFall-Ngai says, it's reasonable to think these influences will eventually be found in other animals. It's possible that microbial partners in the human gut, for instance, could similarly influence human daily rhythms through chemical signaling.

Like all animals, squids make proteins that set their inner clock to environmental light. E. scolopes produces two of these "light entrainment" proteins (cryptochromes, or CRYs), and one is regulated in the squid's head, just like every other animal. McFall-Ngai and her co-authors noticed that escry1, the gene that encodes the other protein, is most highly expressed in the light organ, where the squid houses its glowing bacterial symbionts. "The animal uses the luminescence in the evening, so the luminescence is greatest at night. The gene escry1 cycles with the bioluminescence of the animal and not with environmental light," says McFall-Ngai.

But is it the bacterial luminescence that synchronizes the cycling, or is it the bacteria themselves? It's both, says McFall-Ngai.

The bacteria are necessary for cycling, she says, since squid grown without their bacterial symbionts do not cycle their expression of escry1, and mimicking the bacterial light with a blue light did not induce the cycling.

And they showed that the light is also necessary, because squids grown with defective V. fischeri symbionts that lack the ability to luminesce didn't cycle their expression of escry1 either. With light-defective bacteria in their light organs, squids exposed to the blue light got back on track, cycling escry1 production as usual.

What is it about the bacteria that could be signaling to the squid? Long experience taught McFall-Ngai where to turn next: microbe-associated molecular patterns (MAMPs), molecules that signal the presence of microbes to other creatures. "In this system we have found again and again that bacterial surface molecules are active at inducing all kinds of cellular behavior in the host," says McFall-Ngai.

Her hunch was right. MAMPs plus light turned cycling on. In squid grown without symbionts, light, combined with MAMPs (either the lipid A component of lipopolysaccharide or the peptidoglycan monomer), could induce some degree of cycling. The squid did not respond fully, though, maybe because the MAMPs were only injected into their seawater habitat, not presented directly to the light organ.

The fact that a bacterium can control a daily rhythm in a squid is exciting for other areas of biology, says McFall-Ngai, because all animals, including humans, have clock genes like escry1.

"Recently, in two different studies, biologists have found that there is profound circadian rhythm in both the epithelium [of the human gut] and the mucosal immune system of the gut that is controlled by these clock genes. What are we missing? Are the bacteria affected by or inducing the cycling of the tissues with which they associate?" We don't know," says McFall-Ngai, but it's an area ripe for study.

Moving forward with the squid symbiosis, McFall-Ngai says her lab will try to tie in the transcription of escry1 with cycling in the squid's metabolism to see what changes the squid actually experiences while it's under the spell of its bacterial symbionts.


Story Source:

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


Journal Reference:

  1. Elizabeth A. C. Heath-Heckman, Suzanne M. Peyer, Cheryl A. Whistler, Michael A. Apicella, William E. Goldman and Margaret J. McFall-Ngai. Bacterial Bioluminescence Regulates Expression of a Host Cryptochrome Gene in the Squid-Vibrio Symbiosis. mBio, 2013; DOI: 10.1128/mBio.00167-13

Cite This Page:

American Society for Microbiology. "Symbiotic bacteria program circadian-like rhythms in squid using light and chemicals." ScienceDaily. ScienceDaily, 2 April 2013. <www.sciencedaily.com/releases/2013/04/130402091646.htm>.
American Society for Microbiology. (2013, April 2). Symbiotic bacteria program circadian-like rhythms in squid using light and chemicals. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2013/04/130402091646.htm
American Society for Microbiology. "Symbiotic bacteria program circadian-like rhythms in squid using light and chemicals." ScienceDaily. www.sciencedaily.com/releases/2013/04/130402091646.htm (accessed September 30, 2014).

Share This



More Plants & Animals News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

California University Designs Sustainable Winery

California University Designs Sustainable Winery

Reuters - US Online Video (Sep. 27, 2014) — Amid California's worst drought in decades, scientists at UC Davis design a sustainable winery that includes a water recycling system. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
Argentina Worries Over Decline of Soybean Prices

Argentina Worries Over Decline of Soybean Prices

AFP (Sep. 27, 2014) — The drop in price of soy on the international market is a cause for concern in Argentina, as soybean exports are a major source of income for Latin America's third largest economy. Duration: 01:10 Video provided by AFP
Powered by NewsLook.com
Mama Bear, Cubs Hang out in California Backyard

Mama Bear, Cubs Hang out in California Backyard

Reuters - US Online Video (Sep. 27, 2014) — A mama bear and her two cubs climb trees, wrestle and take naps in the backyard of a Monrovia, California home. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
'Crazy' Climate Forces Colombian Farmers to Adapt

'Crazy' Climate Forces Colombian Farmers to Adapt

AFP (Sep. 26, 2014) — Once upon a time, farming was a blissfully low-tech business on Colombia's northern plains. Duration: 02:05 Video provided by AFP
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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