Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Social amoeba seek kin association

25.11.2008
Starving "social amoebae" called Dictyostelium discoideum seek the support of "kin" when they form multi-cellular organisms made up of dead stalks and living spores, said researchers from Baylor College of Medicine and Rice University in Houston in a report that appears online today in the open-access journal Public Library of Science Biology.

"In fact, these single cells aggregate based on genetic similarity, not true kinship," said Dr. Gad Shaulsky, professor of molecular and human genetics at BCM. However, it demonstrates a discrimination between "self" and "non-self" that is similar to that seen in the immune systems of higher organisms, he said.

Dictyostelium discoideum begins as a single-celled organism. As long as these single cells have sufficient food and a pleasant environment, they are happy to remain that way. However, when food supplies run low, they first move toward one another to form an aggregate. Eventually the aggregate forms a multi-cellular organism made up of spores that can survive and reproduce, and dead cells that form a stalk. The stalk to spore ratio is about one to four.

"Cooperation is one of the success stories of the evolution of life," said Dr. Joan Strassmann, professor and chair of ecology and evolutionary biology at Rice, "Part of that success involves allowing cooperation in a way that controls conflict. One of the best ways to control conflict is cooperating with genetically similar individuals."

This kind of work is important in understanding biofilms, colonies of bacteria or fungi that can harm humans and other mammals, she said. For example, people with cystic fibrosis are vulnerable to the formation of biofilms that can damage the lungs.

In previous work, the collaborators found that Dictyostelium cells sometimes "cheat" by avoiding the deadly stalk pathway, thereby increasing the chances that their genes will be reproduced in future generations.

In this work, they determined that while cheating is still a possibility, the aggregation by genetic similarity reduces the likelihood that the stalk cells will "die" for a genetically distant individual.

"It's not exclusive," said Shaulsky, "but it's a preference. In that context, what are the benefits of cooperating versus the risks? By segregating, they minimize the risk that cells of their genetic similarity will die.'

In the laboratory, the scientists mixed cells from genetically distinct strains and found that they segregate into clusters of genetically similar "kin" after they have aggregated into the multi-cellular form.

"It's as much a self, non-self mechanism as anything," said Strassmann. "The more distant you are genetically, the more able you are to trigger the non-self recognition."

Dr. Elizabeth Ostrowski, a post-doctoral researcher in the Strassmann/(Dr. David) Queller laboratory at Rice and first author on the report, said, "We knew that Dictyostelium was unusual in that it brings different genotypes together in the multi-cellular organism. These results suggest that these organisms also have mechanisms to limit the levels of genetic diversity in the multi-cellular organism." A human's cells, for example, have the same genome everywhere in the body because humans begin development as a single cell.

This kind of work shows the strength of Dictyostelium as a model for understanding other multi-cellular organisms, she said.

"What role does this discrimination for genetic similarity play in the ability of organisms to become multi-cellular?" she said.

"The big thing we found is that Dictyostelium discoideum have social behavior," said Dr. Mariko Katoh, an instructor in molecular and human genetics at BCM and the other first author on the report. "We didn't really know if they could discriminate when the genetic differences were small. That was the surprising part."

In the future, the scientists plan to determine the molecular mechanisms behind the aggregation phenomenon.

Glenna Picton | EurekAlert!
Further information:
http://www.bcm.edu

More articles from Life Sciences:

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

nachricht The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NASA's AIM observes early noctilucent ice clouds over Antarctica

05.12.2016 | Earth Sciences

Shape matters when light meets atom

05.12.2016 | Physics and Astronomy

Researchers uncover protein-based “cancer signature”

05.12.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>