First Person: Joan Strassmann

摘要

When most people hear the word amoeba, they don't think of something that's social. What is "social" about the amoebas you study? Much of the time, D. discoideum are solitary amoebas that eat bacteria in the soil and divide by binary fission. When they starve, though, they aggregate through a cascade of signals and form a multicellular body. This step is extremely interesting because multicellular bodies are usually formed through a single-cell bottleneck [such as the fertilized egg that we all once were]. Because different genotypes-different genetic variants-of D. discoideum can aggregate and form a multi-cellular body in which some cells die and others live, we can test ideas about cooperation and conflict that could not be tested in an organism that doesn't have genetic variability in it. [This is in contrast to multicellular organisms, which have the same genotypes in every cell of their bodies.] If there are different genotypes of D. discoideum in the area, they can come together to form the multicellular body. In a way, the amoebas can fit into the paradigm of a social group [such as ants] or the paradigm of a multicellular body [such as seaweed, flatworms, or humans].