Meeting Abstract

54.4  Tuesday, Jan. 5  Tight Regulation of Large-Scale Genome Rearrangements: the Sea Lamprey (Petromyzon marinus) SMITH, Jeramiah J.*; AMEMIYA, Chris T.; Benaroya Research Institute; Benaroya Research Institute jsmith@benaroyaresearch.org

Our recent computational and empirical studies have revealed developmentally-regulated and large-scale genome reorganizations in a definitively vertebrate genome (the sea lamprey – Petromyzon marinus: a jawless vertebrate). Several lines of evidence demonstrate that the lamprey undergoes a dramatic remodeling of its genome, resulting in the elimination of hundreds of millions of base pairs (~20% of the genome) from many somatic cell lineages during embryonic development. Embryological studies reveal that many of these rearrangements take place early in development, resulting in a situation wherein an individual’s “germline” and “somatic” cell lineages differ substantially in gene content. Computational and array CGH (comparative genomic hybridization) studies reveal that several distinct genomic regions are altered during this process and have identified specific rearrangement breakpoints. Genomic regions that are removed via programmed rearrangements include genes that are transcribed in adult and juvenile testes or during early embryonic development. Some of these somatically-deleted genes have homologs that are known to contribute to genome stability or the specification of reproductive tissues. Notably, ostensibly similar rearrangements have also been observed in hagfish – suggesting that this dynamic genome biology can be traced to a point very near the common ancestor of all vertebrates. Understanding the mechanisms by which lamprey regulates such extensive remodeling of its genome will provide invaluable insight into factors that can promote stability and change in vertebrate genomes, and the consequences of reorganization in the context of “normal” vertebrate development and cell biology.