Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biologists ID molecular block for social ’cheaters’

07.10.2004


Social cooperation is one of the most difficult adaptations for evolutionary biologists to explain because competition for resources inside the collective should lead to evolved traits that allow individuals to "cheat" the collective, win more resources and reproduce faster than their more cooperative neighbors -- thus undermining the social collective. In new research, evolutionary biologists and geneticists at Rice University and Baylor College of Medicine have isolated a genetic mechanism that counters competitive pressures and stabilizes cooperation. Their research appears in the Oct. 7 issue of the journal Nature.



Using the latest tools of molecular genetics, the researchers found that the phenomenon known as pleiotropy -- which occurs when a gene affects more than one inherited trait -- plays a crucial role in preventing "cheaters" from exploiting their neighbors within slime mold colonies that are formed by the social amoeba Dictyostelium discoideum. "What we’ve found is a molecular block to cheating and the genetic mechanism it relies on-- tying cooperative genes tightly with the essential function of reproduction," said paper co-author Joan Strassmann, professor of ecology and evolutionary biology at Rice. "Such a mechanism makes the loss of social genes costly to cheaters, and we believe this pleiotropic mechanism may be indicative of a general mechanism that’s employed in many species to stabilize cooperation."

The Rice-Baylor experiments draw upon one of the most extraordinary examples of social cooperation among microorganisms: when slime mold amoebae run out of the bacteria they eat, they group, then form a fruiting body in which about one-fifth of the single-celled individuals within the colony sacrifice themselves to form the stalk that holds up the spores. Before forming a stalk, the colony goes through a stage where it forms a slug-like structure. During this stage, cells produce a signaling molecule called DIF-1 that causes some members of the colony to differentiate themselves from the rest of the group and enter a prestalk stage of development. Using biotechnology, the research team created a mutant strain of Dictyostelium without the gene dimA, which codes for a key protein that Dictyostelium cells use to recognize DIF-1. "We wanted to see if cells without dimA could cheat the system by ignoring DIF-1 and thereby increase their chances of becoming spore cells rather than stalk cells," said paper co-author David Queller, professor of ecology and evolutionary biology at Rice. "We created colonies that contained roughly a 50-50 mix of our mutants and wild type strains of Dictyostelium, As expected, the dimA knockouts -- the cheaters -- were predisposed to move to the back of the slug, the position occupied by cells in the prespore stage of development."


But despite this advantage during stalk development, the cheaters were far less likely than their native counterparts to make it into the actual spores atop the stalk, a finding that surprised the entire research team. The researchers conducted a series of tests to determine whether the dimA mutants had an unexpected competitive disadvantage that was skewing the results of the experiment. One of those tests involved looking for a marker gene expressed only in prestalk cells. Using this marker gene, they determined that many cells in the spores were wild type cells that were initially tagged to become stalk cells. These cells underwent a late-stage developmental about-face and supplanted dimA knockout cells that were initially targeted to become spores.

"This test confirmed that the dimA gene was essential not only for DIF-1 recognition but also for spore production," said paper co-author Gad Shaulsky, associate professor of molecular and human genetics at Baylor College of Medicine. "We don’t know the precise biomolecular pathway for this second function, but we know that dimA codes for a transcription factor that binds with DNA in the nucleus to control gene expression. Because transcription factors often control more than one gene, we believe the absence of dimA may be interfering with an unknown recognition pathway that is essential for spore selection."

The results are the first published by a unique Rice-Baylor collaborative that won $5 million from the National Science Foundation last year to apply the latest techniques of modern molecular genetics and large-scale genomics to the study of social evolution. The project was one of the first funded by the NSF’s new Frontiers in Integrated Biological Research program.

Other co-authors on the paper, "Pleiotropy as a mechanism to stabilize cooperation," are Kevin Foster, a former Huxley Fellow in ecology and evolutionary biology at Rice who is now a Fellow at the Wissenschaftkolleg in Berlin, and Chris Thompson, a former post-doctoral researcher at Baylor College of Medicine who is now at The University of Manchester.

Jade Boyd | EurekAlert!
Further information:
http://www.rice.edu

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>