Immune systems in simple organisms
Even though
the evolution of an adaptive immune system occurred only recently in an ancestor
of gnathostome vertebrates, all multicellular organisms share other protective
mechanisms against invasive microorganisms. To get into the evolution
of the immune system, we examine host-pathogen interactions in the basal metazoan
Hydra and the molecular basis of self / non-self recognition in the urochordates
Botryllus and Ciona. |
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Science News Focus, 1 May 2009 |
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The ability to distinguish conspecific but genetically different tissue as nonself (allorecognition) is crucial for several biological processes. (a) Allogeneic recognition (allorecognition) can be divided into tissue histocompatibility and recognition events during gamete interactions that precede fertilization. Various modes of allorecognition are unequally distributed within the animal kingdom. Although correct recognition during fertilization is crucial for all animals, natural transplantation occurs only in colonial animals. Only in vertebrates is the molecular basis of histocompatibility known and connected with the function of the immune system. To what extent allorecognition is based on components of the immune system in invertebrates remains unclear. (b) Allograft rejection, colony fusion and block of self-fertilization in different taxonomic groups. The representatives of each animal group in which allorecognition reactions were studied are listed, with the references in square brackets [23 ,25,27–35,36 ,42 ,43–50]. From: Khalturin & Bosch, 2007, Current Opinion in Immunology |
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From: Miller & Hemmrich, 2007, Genome Biology |