Parinaz Fozouni L&S Sciences
The Evolution of the Animal Innate Immune System
All animals share a common ancestor that underwent a transition to evolve multicellularity. To better understand this transition, we compare animals to choanoflagellates, their closest living relatives. Multicellular animals faced many challenges not shared by their unicellular ancestors. One such challenge was the evolution of mechanisms to defend against pathogens seeking to exploit the new niches present in a multicellular organism. My project aims to lay the groundwork for asking whether Toll-like receptors (TLRs), critical components of the innate immune system, evolved in the earliest animals to answer this challenge. As little is understood about choanoflagellate innate immunity, characterizing the role of their putative TLRs will increase our knowledge about choanoflagellate immunity, especially in hypothesizing the changing role of immunity in the evolution of multicellularity. Characterizing the role of these TLRs in choanoflagellates would provide valuable insights into the basic immunological tool kit of the last common ancestor of animals.