Genome Dynamism in a Basal Vertebrate: Challenges and Biological Implications

The lamprey (Petromyzon marinus) is a vertebrate species that undergoes programmed genome rearrangements during embryonic development that results in deletion of ~20% of its germline DNA from the soma. This genomic differentiation of germline and soma is intriguing, because the germline plays a unique biological role, wherein it must retain the ability to undergo meiotic recombination and the capacity to differentiate into every cell type (pluripotency). This sets the germline at odds with somatic tissues since factors that promote recombination and pluripotency in germ cells can potentially disrupt genome integrity or specification of cell fate if misexpressed in other cell types, i.e., germline and soma are in biological conflict. We will discuss the specific genomic challenges we encounter with the lamprey and how such problems may be applicable to de novo genome projects in other vertebrates, as well as the far-reaching biological implications from our analyses.