Altruism and Cooperation in the Social Amoeba Dictyostelium discoideum

K. Manjunath and L. Muthukumar

Presented

by

Prof. K. ManjunathDept. of Microbiology and Biotechnology,

Bangalore University, Bangalore - 56

What is Co-operation?

Multiple individuals or cells engaging in a common task for mutual benefit.

In this image of a tennis doubles match, the men in white are co-operating with each other for the mutual benefit of a combined win/win situation.Whereas the they are competing against the men in black. In a competition there is a loser and a winner.

CHEATING

Cheater

Engaging in behavior that exploits the co-operative behavior of con-specifics by imposing fitness costs on them, while providing fitness benefits to the cheaters.

Co-operator

EVOLUTION HAS INVENTED WAYS OF PREVENTING CHEATING

Kin Selection

Jamieson GorrellNat Commun. 2010 Jun 1;1:22

A mother squirrel adopts a relative’s abandoned Baby squirrel and includes it in her litter. This altruistic behavior is displayed only towards a relatives abandoned baby.

Kin Selection has evolved to prevent and reduce cheating.

Altruism and Cooperation are seen in both Macro and Microrganisms.

With Kin

Adapted from Matt Zimmerman

We are interested in the Social Amoeba Dictyostelium discoideum

Eichenger, L., et al. Nature 2005

Domain: EukaryaKingdom: AmoebozoaSuperphylum: ConosaPhylum: MycetozoaClass: DictyosteliaOrder: DictyosteliidaFamily: DictyosteliidaeGenus: DictyosteliumSpecies: D. discoideum

Raper, 1935

Dictyostelium has a Remarkable Bimodal Life Cycle that shows Behaviors of Altruism and Cooperation at the Microscopic level.

Ostrowski Laboratory

www.nature.comHarwood lab

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D.discoideum amoeba form a Co-operative Organised Membrane Covered Migratory Pseudo-plasmodium

Jacobus J. Boomsma Nature 2011 469, 308–309

www.mun.ca

The Prespore cells of the pseudo-plasmodium form the Spore and the Prestalk cells form the Stalk

Stalk formation is thought of as the classic representation of “ALTRUISTIC behavior with Kin”

The altruistic prestalk cells die to aid the dispersion of the prespore kin cells.

In Summary Both the Behavior of Amoeba in Slug Formation and Migration and the Stalk cells are the simplest Representation of Co-operation and Altruism respectively as seen in macro-organisms

Dictyostelium is increasingly being studied as a Model Organism for Genes that Enhance Altruistic Behavior i.e. Stalk Formation or Enhance Cheating i.e. Spore Formation.

Aggregating Amoeba from Multiple Clones from the Wild Cheat by Contributing Less than their Share Towards the Sterile Stalk.

Strassman 2000, Nature Volume 204

The ChtB mutant Dictyostelium Contributes More than its Fair Share Towards Spores and Inhibits Wild-Type Strains From forming Spores.

Santorelli et al 2013

Polyketides Act as Morphogens in Dictyostelium

The DiPKS1 gene product Polyketide MPBD is required for spore maturation

wild knockout

Narita et al 2005

DiPks1 and DiPks37 are required for Stalk to Spore Ratio

Lavanya Muthukumar, Alzu Manocha, NII, New Delhi 2011.

50% 50%AX2 DiPKS1/37Dko30% 70%

DiPks14 is Required For Normal Slug Formation and Migration

WT PKS14 K/O

1mm 1mm

Lavanya Muthukumar, Bangalore University 2013

Microarray analysis of DiPKS14KO Strains Show a Down Regulation of Gene Transcripts Involved in Protein Synthesis

SLUG SLUG

MOUNDMOUND

FB FB

Lavanya Muthukumar, Bangalore University 2013

Kinselection, altruism, reciprocal altruism, interdependent fortunes

Summary

1. PKS genes which produce Morphogens such as DIF1 and MPBD are

involved in spore and stalk cell fate determination enhancing either stalk or

spore Cell fate.

2. DiPKS14 gene also seems to be required for appropriate behavior of the

co-operative organized pseudoplasmodium, such as slug size and slug

migration.

3. Whether DiPKS14 affects slug behavior by influencing stalk and spore cell

ratios remains to be determined.

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