Dr. De Tomaso received his BS degree in Biology from Stanford University and his PhD in Cellular and Molecular Biology at Washington University School of Medicine in St. Louis. His doctoral thesis focused on understanding the mechanisms of multi-subunit protein assembly and targeting, using the rodent Na,K-ATPase. Following completion of his PhD, Dr. De Tomaso was a NIH fellow in the laboratory of Irv Weissman at Stanford University, where he worked on both delineating the molecular mechanisms which underlie allorecognition in the primitive chordate, Botryllus schlosseri, as well as understanding the cellular and molecular basis of regeneration in this organism.
Research in our lab is based around the phenomenon of self/non-self recognition (allorecognition) in a primitive chordate organism, Botryllus schlosseri. This allorecognition reaction links a number of disparate fields, including immunology, stem cell, developmental, and evolutionary biology, and also has ecological consequences. Several unique aspects of the Botryllus life history make it a novel, experimentally accessible model organism to ask pertinent questions in these distinct disciplines.
Botryllus individuals undergo a natural transplantation reaction when they come into contact with other members of the same species. Using a combination of genetic, genomic and cell biological approaches, we are focused on understanding the molecular mechanisms which underlie this reaction, which is similar to the MHC-based allorecognition found in the vertebrates, and functionally resembles the way in which bone marrow transplants are recognized and rejected in mice and humans. This allorecognition system exists to prevent the transplant of blood-borne pluripotent stem cells, which once transferred can parasitize other genotypes, replacing their somatic and/or germline tissues. Parasitic abilities are genetically determined and autonomous to the cells themselves, and we are studying the mechanisms which underlie these properties. Transplanted stem cells are able to parasitize other individuals because the adult body plan of Botryllus is colonial, and has an asexual reproductive pathway that can regenerate adult individuals through an independent developmental program lacking any embryonic stages-the only chordate which can do so. The developmental pathways which control the expansion, differentiation, and patterning of asexual regeneration are unknown, and we are studying this process using a variety of techniques. Botryllus occupies a key position in vertebrate evolution, and these studies may provide insights into the origins of many chordate innovations.
Kassmer, S.H., Langenbacher A., and De Tomaso A.W. (2019) Primordial Blasts, a population of blood borne stem cells responsible for whole body regeneration in a basal chordate. bioRxiv, 647578
Kassmer, S.H., Nourizadeh, H., and De Tomaso A.W. (2019) Cellular and molecular mechanisms of regeneration in colonial and solitary Ascidians Dev Biol 448:271-278
Kassmer, S.H., Rodriguez D., and De Tomaso, A.W. (2018) ABC-transporter activity and eicosanoid-signaling are required for germ cell migration a basal chordate bioRxiv, 469098
Rodriguez D, Braden BP, Boyer SW, Taketa DA, Setar L, Calhoun C, Maio AD, Langenbacher A, Valentine MT, and De Tomaso AW. (2017) In vivo manipulation of the extracellular matrix induces vascular regression in a basal chordate. Mol Biol. Cell. 28:1883-1893.
Nydam ML, Stephenson EE, Waldman CE, and De Tomaso AW. (2017) Balancing selection on allorecognition genes in the colonial ascidian Botryllus schlosseri.Dev Comp Immunol. 69:60-74.