Evolution of Adaptive Immunity

Future Work/Research

Further research and more work in this field of immunobiology needs to take place to address the questions still brewing.

• What is the nature of the RAG transposon?
• What are the functions of antigen receptors in different organisms?
• How is the VLR system regulated?
• Did T-and B-like lymphoid cells really emerge in the common ancestor of jawless and jawed vertebrates
• What were the pressures that selected for the emergence of the AIS?

My Hypothesis

The evolution of viruses and bacterial infections has caused the adaptive immune system to become more responsive and effective in terminating more various types of invaders.

With the continued development and evolution of technology and the expansion of the processes that evolutionary biologist use, I am confident that the answers to these questions can some day be resolved.

MY HYPOTHESIS

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Alternative AIS in Jawless Fish

Works Cited

The New Adaptive Immune System

Scientists have come to the astonishing conclusion that the jawless fish that lived 500 million years ago possessed an alternate form of adaptive immunity comprised of variable lymphocyte receptors that was strikingly similar to the system in jawed fish.

DIFFERENCE:

Jawless AIS

Jawed AIS

VS

From then to now

Antibodies in the jawed AIS were used for antigen recognition

B/T cell Receptors

VLR

The jawed fish that lived 500 mya possessed an adaptive immune system that protected and prevented the growth of pathogen growth by using:

• diverse immunoglobulins (antibodies) to detect antigens and other pathogens
• B-cells that help produce antibodies
• T-cells that recognize and kill virus-infected cells directly and maintain the memory of past antigens

Variable lymphocyte receptors (VLR) in the jawless AIS used for antigen recognition

The first jawed fish that walked on land from water carried the RAG-based AIS and passed it on as an inheritable traits to its offspring, and eventually reptiles, and then us. We as mammals share essentially the same immune system as those jawed fish. When it comes down to it, the development of antibodies that protect vertebrates against the increasing diversity of invaders is the primary example of the evolution of the adaptive immunity system.

Bartl, Simon. "Did the Molecules of Adaptive Immunity Evolve from the Innate Immune System?" Oxford Journals. Oxford University Press, 6 Jan. 20002. Web. 05 June 2016. <http://icb.oxfordjournals.org/content/43/2/338.full>.

Boundless. "Whole-Genome Duplication - Boundless Open Textbook."Boundless. Boundless Biology, 26 May 2016. Web. 05 June 2016. <https://www.boundless.com/biology/textbooks/boundless-biology-textbook/evolution-and-the-origin-of-species-18/evolution-of-genomes-127/whole-genome-duplication-509-13089/>.

Dehal, Paramvir. "Two Rounds of Whole Genome Duplication in the Ancestral Vertebrate." PLOS Biology:. Public Library of Science, 6 Sept. 2005. Web. 05 June 2016. <http://journals.plos.org/plosbiology/article?id=10.1371%2Fjournal.pbio.0030314>.

Flajnik, Martin F., and Masanori Kasahara. "Origin and Evolution of the Adaptive Immune System: Genetic Events and Selective Pressures."Nature Reviews. Genetics. U.S. National Library of Medicine, 04 Jan. 2010. Web. 04 June 2016. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3805090/>.

Fugmann, Sebastian D. "The Origins of the RAG Genes – from Transposition to V(D)J Recombination." Seminars in Immunology. U.S. National Library of Medicine, 04 Feb. 2010. Web. 04 June 2016. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2823946/>.

Herrin, Brantley R. "Alternative Adaptive Immunity in Jawless Vertebrates."Alternative Adaptive Immunity in Jawless Vertebrates. The Journal of Immunology, 10 May 2010. Web. 04 June 2016. <http://www.jimmunol.org/content/185/3/1367.full>.

Janeway, Charles A., Jr. "Evolution of the Adaptive Immune Response."National Center for Biotechnology Information. U.S. National Library of Medicine, 23 Mar. 2001. Web. 05 June 2016. <http://www.ncbi.nlm.nih.gov/books/NBK27108/>.

Lee, Jie-Oh. "Structural Diversity of the Hagfish Variable Lymphocyte Receptors*." Structural Diversity of the Hagfish Variable Lymphocyte Receptors. The Journal of Biological Chemistry, 17 Nov. 2006. Web. 05 June 2016. <http://www.jbc.org/content/282/9/6726.long>.

Doubling of Genetic Material

Provides organisms with redundant alleles that can evolve freely with little selection pressure

The duplicated genes can undergo neofunctionalization or subfunctionalization which could help the organism adapt to the new environment or survive different stress conditions

Evolution of Adaptive Immunity

Whole Genome Duplication

Changes in gene expression

• Leads to massive evolutionary change
• Doubling genetic material
• changes in gene expression

The RAG transposon and other genes that are important in maintaining the AIS that were dormant in the jawless fish species, became active during the speciation of the jawed fish from the jawless

My Hypothesis

Recombinant-Activating Gene

(RAG)

Importance of Adaptive Immunity

• encodes enzymes participate in the rearrangement and recombination of the genes of immunoglobulin, B and T receptor molecules

Allows an organism to produce RAG protein/enzymes that changes the genes to fit the antigen it is defending against appropriately.

• Antibodies, B/T cells, and
• Immunological memory
• Protects the body from antigens and pathogens that the innate immune system does not protect against

• involved in the hypermutation of B receptor genes.

Allow antibodies to recognize various antigens by mutating their DNA and changing super fast

The evolution of viruses and bacterial infections has caused the adaptive immune system to become more responsive and effective in terminating more various types of invaders.

Emergence of Adaptive immunity

500 mya, there were two superclasses of fish. One jawed, the other jawless. Two macroevolutionary events are believed to have attributed to the genesis of the AIS (Adaptive Immunity System): the emergence of the recombination-activating gene (RAG) transposon and two rounds of whole-genome duplication.