Botryllus schlosseri, a Model Organism for the Study of Tissue Regeneration and the Evolution of Immunity

Botryllus schlosseri is a colonial urochordate that follows the chordate plan of development following sexual reproduction, but invokes a stem cell-mediated budding program during subsequent rounds of asexual reproduction. Botryllus schlosseri exhibits a genetically determined natural transplantation reaction, whereby self-recognition between colonies leads to formation of parabionts with a common vasculature, and contact between incompatible colonies leads to rejection.. Following vascular fusion, stem cells from each Botryllus schlosseri colony compete to overtake germline and/or somatic lineages. Stem cell competition may lead to elimination of the other colony’s genome, or may produce a chimeric colony with mixed genotypes. To gain insight into the evolution and molecular basis of histocompatibility, alternative modes of reproduction, and stem cell-mediated regeneration we sequenced the Botryllus schlosserigenome and transcriptome.

This talk will focus on the method we developed to sequence and assemble a highly repetitive genome (Voskobotnik et al., 2013; eLife), highlight the genomic events underlying the evolution of vertebrates and lymphoid-mediated immunity (Voskobotnik et al., 2013; eLife), and describe the methods used to pinpoint a single gene that encodes self/non-self and determines “graft” outcomes in Botryllus schlosseri (Voskoboynik et al., 2013; Science).