BLG 667 Lecture Notes - Lecture 19: Adaptive Immune System, White Blood Cell, Tunicate
29 Oct 2016
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Document Summary
Invertebrates but deuterostomes have more complex immune systems: many genes coding for immune receptors major evolutionary change, circulating coelomocytes important, no closed circulatory system. Cephalochordates: proteins in ig superfamily, roles have not yet been determined, capable of innate immunity, do not have adaptive immunity. Urochordates aka tunicates: milestone in evolution of adaptive immunity, no t-cells but have a genetic sequence similar to that in vertebrates, early evolution of elements later co-opted, many genes coding for innate immunity aspects. A mutation of the genetic sequence resulted later in t-cells. Since then, we have seen the evolution of many genes that are going to be involved in innate immunity. So what big step changed the game for vertebrates: elements vital to regulation of mhc activity became co-opted and evolved. *mhcs appeared when vertebrates split off of urochordates. Because they didn"t have mhcs yet, they weren"t able to use t-cells.
