Who's who in multicellularity. Self-nonself recognition in multicellular organisms that form chimeras. (a) Cryphonectria parasitica, the causal agent of chestnut blight. Hyphal fusion is restricted to strains that match at all vegetative incompatibility loci [71,72]. Incompatible reactions result in localized cell death and the formation of a barrage zone. Of the six pairings shown, only two (bottom right) are compatible. (b) In the marine tunicate Botryllus schlosseri, fusion or rejection is controlled by a highly polymorphic locus containing multiple immunoglobulin domains (FuHC) . A single population can contain hundreds of different alleles. (c) In the social amoeba Dictyostelium discoideum, thousands of cells aggregate (far left) and subsequently develop into a fruiting body (far right). Cells of genetically different individuals can partially separate during multicellular development . C. parasitica photo by Kent Loeffler, courtesy of the Department of Plant Pathology and Plant-Microbe Biology at Cornell University. B. schlosseri photo courtesy of Tony de Tomaso, University of California, Santa Barbara. D. discoideum, courtesy of Gerda Saxer, Rice University.
Ostrowski and Shaulsky Genome Biology 2009 10:218 doi:10.1186/gb-2009-10-5-218