Featured Research

from universities, journals, and other organizations

In sync: Squid, glowing companions march in genetic harmony

Date:
January 28, 2010
Source:
University of Wisconsin-Madison
Summary:
Most humans are blissfully unaware that we owe our healthful existence to trillions of microbes that make their home in the nooks and crannies of the human body, primarily the gut. During evolutionary history, humans and bacteria have forged a mutually beneficial coexistence that provides the microbes' room and board in exchange for an array of biochemical services that help support everything from the digestion of food to a robust immune system. But the intimate details of the relationship -- how the cells of the host and the cells of the bacteria coexist and interact -- are murky.

The genetic interplay between the Hawaiian bobtail squid (pictured) and the symbiotic bacteria that colonize its predator-fooling light organ have been charted to reveal a daily rhythm that sets the stage for a balanced, lifelong relationship. The new knowledge of the genetic crosstalk between squid and bacterium, discovered by Margaret McFall-Ngai, a professor of medical microbiology and immunology, may help scientists better understand symbiosis, as well as similar tactics employed by the bacteria that make us sick.

Most humans are blissfully unaware that we owe our healthful existence to trillions of microbes that make their home in the nooks and crannies of the human body, primarily the gut.

Related Articles


During evolutionary history, humans and bacteria have forged a mutually beneficial coexistence that provides the microbes' room and board in exchange for an array of biochemical services that help support everything from the digestion of food to a robust immune system.

But the intimate details of the relationship -- how the cells of the host and the cells of the bacteria coexist and interact -- are murky. Now, however, with the help of a diminutive Pacific Ocean squid and the bioluminescent bacteria that colonize its light-emitting, predator-fooling organ, scientists may have found a key to how animal hosts and their microbial symbionts maintain a healthy, rhythmic coexistence.

In a study published the week of Jan. 18 in the Proceedings of the National Academy of Sciences, researchers led by Margaret McFall-Ngai and Edward Ruby, professors of medical microbiology and immunology at the University of Wisconsin-Madison, chart the genetic interplay of symbiosis, revealing a daily molecular choreography that may well be characteristic of higher animals, including humans. If true, the insight would have important practical implications for human and animal health, as similar events occur when our tissues are colonized by the germs that make us sick.

"Nobody has a good handle on how the balance between host and symbiont is achieved," notes McFall-Ngai.

The Wisconsin researchers have studied the symbiotic interplay between the tiny Hawaiian bobtail squid, a two-inch creature common to the warm waters of the Pacific, and a glowing bacterium, Vibrio fischeri, for more than 20 years. The microbe colonizes and powers the animal's light organ, which serves to confuse squid predators lurking in the ocean depths at night when the squid is most active.

The idea behind the new study, explains McFall-Ngai, was to document the daily genetic dialogue between the bacterial symbionts and host-squid cells. Using microarrays that reveal which genes of the partners in an interaction are turned on or off, the group led by McFall-Ngai and Ruby found a daily pattern of activity that seems to show how host and bacterium maintain a healthy and balanced relationship.

"We found it is an extremely dynamic interaction, a profound daily rhythm on the part of both partners," says McFall-Ngai.

Several years ago, the Wisconsin researchers discovered that each day at dawn the bobtail squid expels about 90 percent of the bacteria that colonize its light organ. It had also been noted that the intensity of the bacterium's bioluminescence waxed and waned, with the most light produced at night when the squid is most active and most vulnerable to predators.

The new PNAS study assessed at different times of day the genetic activity of the squid host cells that support the bacterial symbionts as well as the bacteria themselves.

"Just before dawn, the animal turns on the majority of the genes associated with the cytoskeleton," the internal scaffolding of cells, according to McFall-Ngai. A close look at the tissues using electron microscopy revealed that the structure of the tissue colonized by Vibrio fischeri was dramatically disrupted at that time, with portions of the host-squid membranes shed into the spaces that the bacteria colonize.

Similar cytoskeletal changes have previously been observed in human pathogenesis, for example, in the destruction of intestinal tissues by E. coli 0157, which occurs in contaminated hamburger.

In the case of the squid, just after dawn and following the daily expulsion of the symbionts, the animal shuts down the genes of the cytoskeleton. As the residual symbionts begin to repopulate the tissues, the squid's cells regain their highly organized daytime condition. In response to the released host membranes, the bacteria turn on all the genes and pathways associated with using those membranes as food. Once that nutrient supply is exhausted, the squid then provide the symbionts with complex sugars for sustenance.

The bacteria, says McFall-Ngai, seem to be cycling through different metabolic states in response to different food sources provided by the host. The details teased out of the squid and its bioluminescent bacterium, says McFall-Ngai, may be more generally applicable to animal-microbial associations: "It is quite likely that such daily rhythms on the maintenance of animal-bacterial symbioses are more universal than in just this little squid."

The study was supported by grants from the W.M. Keck Foundation, the National Institutes of Health and the National Science Foundation.


Story Source:

The above story is based on materials provided by University of Wisconsin-Madison. The original article was written by Terry Devitt. Note: Materials may be edited for content and length.


Journal Reference:

  1. Wier et al. Transcriptional patterns in both host and bacterium underlie a daily rhythm of anatomical and metabolic change in a beneficial symbiosis. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.0909712107

Cite This Page:

University of Wisconsin-Madison. "In sync: Squid, glowing companions march in genetic harmony." ScienceDaily. ScienceDaily, 28 January 2010. <www.sciencedaily.com/releases/2010/01/100127223616.htm>.
University of Wisconsin-Madison. (2010, January 28). In sync: Squid, glowing companions march in genetic harmony. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2010/01/100127223616.htm
University of Wisconsin-Madison. "In sync: Squid, glowing companions march in genetic harmony." ScienceDaily. www.sciencedaily.com/releases/2010/01/100127223616.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Cambodian Capital's Only Working Elephant to Retire in Jungle

Cambodian Capital's Only Working Elephant to Retire in Jungle

AFP (Nov. 25, 2014) Phnom Penh's only working elephant was blessed by a crowd of chanting Buddhist monks Tuesday as she prepared for a life of comfortable jungle retirement after three decades of giving rides to tourists. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Buzz60 (Nov. 24, 2014) A Swedish Adventure racing team travels to try and win a world title, but comes home with something way better: a stray dog that joined the team for much of the grueling 430-mile race. Jen Markham has the story. Video provided by Buzz60
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