Organisms such as plants, fungi and primitive animal life are classified as having an innate immune system, which defends against invaders by recognizing predetermined patterns of molecules. About 520 million years ago, a different form of immunity emerged - the adaptive immune system, shared by humans and other organisms with jaws and vertebrae. This type relies on an army of antibodies and other immune system cells to customize its response to an array of pathogens and remember the encounter for future reference.
"We were asking the question why and where did this sharp division occur? What were the most primitive organisms that exhibit the molecules that we use in our adaptive immune systems?" Ostrov said.
"In this study, we have identified the missing link between the innate immune system and the adaptive immune system, and we have found this link just below the level of jawed vertebrates," he said. "We found an intermediate. We found an immune system that is possessing features of both the innate immune system and the adaptive system."
In their most recent study, UF and USF scientists - including geneticist Gary Litman, of USF's Moffitt Cancer Center - bombarded a highly concentrated, crystallized form of an immune system protein isolated from the fish with X-rays, yielding incredibly high-resolution images of its structure. The lancelet also is known as amphioxus, or by the scientific name Branchiostoma floridae.
"We were surprised not only by how similar the molecules are to our immune response proteins but also that the crystals diffracted to a level of resolution that no one has ever been able to achieve studying these adaptive immune response proteins - atom
Source:University of Florida