Colonial animals typically display the capacity to discriminate between their own tissues and those of unrelated members of their own species, the recognition event culminating in either fusion or rejection. Such allorecognition systems have long been of interest to geneticists by virtue of the substantial allotypic diversity they display. The sequencing of the Hydractinia symbiolongicarpus allorecognition complex will give population geneticists the tools necessary to explore the high diversity of this system and will reveal whether that diversity arises by an unusual genomic architecture. In addition, evolutionists are interested in the role that allorecognition interactions play in mediating conflicts in the units of selection (when selection on the whole favors a different outcome than selection on the parts, such as in human malignancy). Identification of the genes controlling allorecognition will provide the opportunity for evolutionists to study a system that regulates these conflicts.
Immunologists have long maintained that these phenomena lie at the root of vertebrate immunity. Invertebrate allorecognition is therefore of immediate interest in exploring the evolution of the immune system and in identifying candidate vertebrate homologs that might encode human innate immune primers to self.
Finally, the coupling of allorecognition to the mechanisms and outcomes of intraspecies competition are of interest to ecologists. Many hard surfaces in the sea are dominated by encrusting colonial organisms that must compete for space. Sequencing of this invertebrate allorecognition complex will be the first genetic understanding of a mechanism mediating spatial competition.
CSP project participants: Leo W. Buss (proposer) and Stephen Dellaporta (Yale Univ.).