A better way to discover gene function in the social amoeba Dictyostelium discoideum
- Division of Biology, University of California San Diego, La Jolla, California 92093, USA
- Correspondence: Hillary Sussman, Executive Editor, hsussman{at}cshl.edu
This extract was created in the absence of an abstract.
For many years, the social amoeba Dictyostelium discoideum has served as a system to understand what it takes to generate a multicellular organism. Biochemistry and biophysics have defined many of the underlying interactions of protein and cytoskeletal complexes, and sequence analyses have quantitatively defined the changes in gene expression programs. However, the dearth of genetic studies that offer insight into the roles of specific genes has prevented the more widespread use of this fascinating model organism. The eukaryotic amoebas of Dictyostelium provide all the advantages of growth as a microorganism and development as a multicellular organism. As a consequence, they can be analyzed using the techniques of microbial genetics that rely on having millions, even billions, of cells from which to select rare mutant strains; at the same time, they present a myriad of multicellular phenotypes from which to pick. The fact that Dictyostelium can grow and develop just as well as a haploid or a diploid makes the initial screening for mutants fast and simple and allows straightforward mapping by complementation. Dominance and recessivity can be easily determined in diploids formed with wild-type strains.
These characteristics were exploited from 1950 to 1990, initially by Maurice Sussman at Brandeis University in Massachusetts, and then by John Asworth, Bill Loomis, Peter Newell, Keith Williams, Kai Yanagisawa, and their students all over the world, who collectively formed the Dictyostelium community (Newell 1978; Loomis 1987). N-methyl-N′-nitro-N-nitrosoguanidine (NTG) was soon found to be the mutagen of choice that allowed a large number of morphological and temperature-sensitive mutants to be isolated. Loci were recognized by failure of alleles to complement in diploids and then mapped to specific chromosomes by parasexual genetics. The developmental genes could be formally arranged in dependent hierarchies, but there was no way to know what …
