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 A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>