Featured Research

from universities, journals, and other organizations

Worm bites off enough to chew: Ingenious evolutionary trick

Date:
July 5, 2010
Source:
Max-Planck-Gesellschaft
Summary:
Dramatic scenes are played out under Ralf Sommer’s microscope: his research object, the roundworm Pristionchus pacificus bites another worm, tears open a hole in its side and devours the oozing contents. The squirming victim does not stand a chance in this duel: Caenorhabditis elegans may be a close relative of Pristionchus; unfortunately, however, it does not have the same strong "teeth". Pristionchus’ impressive hunting technique though is not the focus of interest for the biologists. Their concern is the development of its mouthparts.

Sequence of images (from left to right) showing how Pristionchus pacificus preys upon a smaller Caenorhabditis elegans worm. P. pacificus bites a C. elegans worm (left), tears open a hole in its side (middle) and devours the oozing contents (right).
Credit: Max Planck Institute for Developmental Biology / Andreas Weller

Dramatic scenes are played out under Ralf Sommer's microscope: his research object, the roundworm Pristionchus pacificus, bites another worm, tears open a hole in its side and devours the oozing contents.

The squirming victim does not stand a chance in this duel: Caenorhabditis elegans may be a close relative of Pristionchus; unfortunately, however, it does not have the same strong "teeth." Pristionchus' impressive hunting technique though is not the focus of interest for the biologists from the Max Planck Institute for Developmental Biology in Tübingen. Their concern is the development of its mouthparts.

Gilberto Bento and Akira Ogawa from Sommer's team have discovered the control mechanism that lies behind the development of the organism's mouth: if the worm grows up with an abundant supply of bacteria as its source of nutrition, it only develops very small teeth and a narrow oral cavity. If it experiences a lack of food or a high population density at the larval stage, it develops a wide mouth equipped with strong teeth-like denticles. (Nature July 1, 2010)

Worms with wide mouths do not differ genetically from their narrow-mouthed counterparts: "Environmental factors dictate the kind of mouthparts formed by roundworms," says Ralf Sommer, Director of the Department of Evolutionary Biology at the Max Planck Institute for Developmental Biology in Tübingen.

If there is a shortage of food during a sensitive phase in larval development, almost all of the worms develop a wide and heavily-armed mouth. One of the worms' pheromones also triggers the same effect. When this pheromone is present in high concentrations, it signals the presence of high population density. In both cases -- that is, food shortage and overpopulation -- a signalling pathway specific to the worm is activated, which results in the development of strong teeth, thereby enabling predatory behaviour. This signalling pathway is already known to the researchers: the hormone dafachronic acid and its receptor also ensure that, in times of scarcity, the worms do not develop into adult individuals but remain in a dormant larval state until the environmental conditions improve again.

"Pristionchus' mouth dimorphism demonstrates two fascinating evolutionary principles simultaneously," says Sommer. First, it shows how frugally evolution works: signalling pathways that have already been established are re-used in a new context -- biologists refer to this process as co-option. In order to assign a new significance to a signalling chain, all that needs to be done is to activate it at a different time or with a different concentration of the signalling molecule that triggers its activation, as occurs in this case. Moreover, the existence of alternative body structures is viewed as paving the way for evolution: "In order to change the mouth structure permanently, the genetic control would only have to be decoupled from the environmental dependency," explains Ralf Sommer.

Whether Prisionchus' stronger mouth structure is better suited to the hunting of other worms or consumption of fungi, is something the Tübingen scientists have only been able to speculate about thus far. "The fact that the mouth dimorphism became established in the course of evolution would suggest that it offers an important advantage in the natural world," says Ralf Sommer.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Gilberto Bento, Akira Ogawa, Ralf J. Sommer. Co-option of the hormone-signalling module dafachronic acid%u2013DAF-12 in nematode evolution. Nature, 2010; DOI: 10.1038/nature09164

Cite This Page:

Max-Planck-Gesellschaft. "Worm bites off enough to chew: Ingenious evolutionary trick." ScienceDaily. ScienceDaily, 5 July 2010. <www.sciencedaily.com/releases/2010/07/100701081901.htm>.
Max-Planck-Gesellschaft. (2010, July 5). Worm bites off enough to chew: Ingenious evolutionary trick. ScienceDaily. Retrieved April 16, 2014 from www.sciencedaily.com/releases/2010/07/100701081901.htm
Max-Planck-Gesellschaft. "Worm bites off enough to chew: Ingenious evolutionary trick." ScienceDaily. www.sciencedaily.com/releases/2010/07/100701081901.htm (accessed April 16, 2014).

Share This



More Plants & Animals News

Wednesday, April 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) — Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) — A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Ebola Outbreak Now Linked To 121 Deaths

Ebola Outbreak Now Linked To 121 Deaths

Newsy (Apr. 15, 2014) — The ebola virus outbreak in West Africa is now linked to 121 deaths. Health officials fear the virus will continue to spread in urban areas. Video provided by Newsy
Powered by NewsLook.com
In Washington, a Push to Sterilize Stray Cats

In Washington, a Push to Sterilize Stray Cats

AFP (Apr. 14, 2014) — To curb the growing numbers of feral cats in the US capital, the Washington Humane Society is encouraging residents to set traps and bring the animals to a sterilization clinic, after which they are released.. Duration: 02:29 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:
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