The Hydractinia allorecognition system

AbstractHydractinia symbiolongicarpus is a colonial hydroid and a long-standing model system for the study of invertebrate allorecognition. TheHydractinia allorecognition system allows colonies to discriminate between their own tissues and those of unrelated conspecifics that co-occur with them on the same substrate. This recognition mediates spatial competition and mitigates the risk of stem cell parasitism. Here, I review how we have come to our current understanding of the molecular basis of allorecognition inHydractinia. To date, two allodeterminants have been identified, calledAllorecognition 1 (Alr1) andAllorecognition 2 (Alr2), which occupy a genomic region called the allorecognition complex (ARC). Both genes encode highly polymorphic cell surface proteins that are capable of homophilic binding, which is thought to be the mechanism of self/non-self discrimination. Here, I review how we have come to our current understanding ofAlr1 andAlr2. Although both are members of the immunoglobulin superfamily, their evolutionary origins remain unknown. Moreover, existing data suggest that the ARC may be home to a family ofAlr-like genes, and I speculate on their potential functions.
Source: Immunogenetics - Category: Genetics & Stem Cells Source Type: research