proper place and at the proper time. Research supports the existence of an extracellular signal, A-factor, which is necessary for developmental gene expression and for the development of a complete fruiting body. Ability to eavesdrop It has been shown that an M. xanthus swarm is capable of eavesdropping on the extracellular signals that are produced by the bacteria it preys upon, leading to changes in swarm behaviour increasing its efficiency as a predator. This allows for a highly adaptive physiology that will have likely contributed to the near ubiquitous distribution of the myxobacteria. Importance in research The complex life cycles of the myxobacteria make them very attractive models for the study of gene regulation as well as cell to cell interactions. The traits of M. xanthus make it very easy to study, and therefore important to research. Laboratory strains of M. xanthus are available that are capable of planktonic growth in shaker culture, so that they are easy to grow in large numbers. The tools of classical and molecular genetics are relatively well-developed in M. xanthus. Although the fruiting bodies of M. xanthus are relatively primitive compared with, say, the elaborate structures produced by Stigmatella aurantiaca and other myxobacteria, the great majority of genes known to be involved in development are conserved across species. In order to make agar cultures of M. xanthus grow into fruiting bodies, one simply can plate the bacteria on starvation media. Furthermore, it is possible to artificially induce the production of myxospores without the intervening formation of fruiting bodies, by adding compounds such as glycerol or various metabolites to the medium. In this way, different stages in the developmental cycle can be experimentally isolated. The genome of M. xanthus has been completely sequenced. The size of its genome may reflect the complexity of its life cycle. At 9.14 megabase, it had the largest known prokaryotic genome until the sequencing of Sorangium cellulosum (12.3 Mb), which is also a myxobacterium. Developmental cheating Social cheating exists among M. xanthus commonly. As long as mutants are not too common, if they are unable to perform the group beneficial function of producing spores, they will still reap the benefit of the population as a whole. Research has shown that 4 different types of M. xanthus mutants showed forms of cheating during development, by being over-represented among spores relative to their initial frequency in the mixture. Evolution In 2003, two