Seminar Details

Redefining gene diversification dogmas: Lessons from the immune system of echinoderms




Dr. Matan Oren - Dept of Biological Sciences, The George Washington University, USA


Over evolutionary time, immune systems in a wide range of organisms have acquired different gene diversification mechanisms to adapt to changing environments and rapidly evolving pathogens. One of the most successful mechanism is the V(D)J somatic recombination which give rise to the enormous diversity of Immunoglobulins and T cell receptors. So far, this type of adaptive immunity has been found only in higher vertebrates and its sudden evolutionary appearance is still enigmatic. We are studying an immune gene family in the California purple sea urchin; the Sp185/333. This gene family exemplifies unique structural features including modular exonal units, gene clustering, microsatellites surrounding genes, segmental duplications and allelic mispairing. We found that single sea urchin cells express a single Sp185/333 message and that the genomic Sp185/333 repertoire is different among different individuals and among single cells within an individual. Interestingly, the purple sea urchin, express all basic genes required for V(D)J recombination including RAG1 and RAG2. We also identified two clusters of recombination signal sequences (RSS) in proximity to the Sp185/333 genes. We therefore suspect that a vertebrate-like RAG complex is involved in the Sp185/333 DNA rearrangements.

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