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Cephalopods: A Curious Case of Self-Gene Editing

 

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For the last 150 years, Charles Darwin’s Theory of Evolution and Gregor Mendel’s work with genetics have the backbone of biology. Darwin’s Theory of Evolution suggests that all organisms originated from one common ancestor and over time slowly evolved through a process called natural selection. Natural selection is a process where organisms that are better equipped for survivals in certain environments outlive other organisms and reproduce. Those offspring become equipped to survive in certain conditions and the expression of a certain adaptation within specific populations will increase, slowly eliminating other characteristics that are unfavorable [1]. Mendelian genetics discovered the science of heredity and how traits are transmitted between parent and offspring in genes. Gregor Mendel’s findings can be summarized into two principles: The Principle of Segregation and the Principle of Independent Assortment. The Principle of Segregation says that for any trait, the parent only passes down one version of that allele to its offspring and the Principle of Independent Assortment says that each allele is passed down to offspring independently, allowing for variations that neither parents possess [4]. These two principles, in tandem with Charles Darwin’s Theory of Evolution, which combined are known as neo- darwinism, have been the basis of genetics.

Recently, scientists have made a discovery that reject the ideas of neo-darwinism in cephalopods. Cephalopods, which include octopus, squid, and cuttlefish, are capable of directly editing their genes through RNA editing. In most organisms, ribonucleic acid (RNA) works as a middle man between DNA and protein synthesis. RNA essentially makes a copy of DNA and sends a message to ribosomes, where protein synthesis takes place. In cephalopods, scientist found hundreds of thousands of RNA editing sites within their genomes, as opposed to the rare few that are found in all other organisms. Given that cephalopods directly edit their RNA, they can manipulate the proteins synthesized from their genome, greatly increasing the range of their proteome [3]. Scientist hypothesize that their ability to edit RNA has allowed cephalopods to develop a more intelligent brain and use tools like complex camouflage.

Although RNA editing is fascinating, it has come at the expense of evolution within cephalopods. By foregoing the mechanisms of evolution, these curious creatures have been able to retain a vast database of genetic material and has allowed them to fine-tune their proteins [5]. Scientist have found this being expressed in the brain tissue, where RNA editing has resulted in complex tissues that have allowed for more efficient functionality.

While scientists are still studying the science and mechanisms behind RNA editing, they hope that one day RNA editing will be the solution to genetic disorders and the issues of ethics behind directly editing the genome using techniques like CRISPR [2] . For now, we can just marvel at these alien-like creatures that inhabit the Earth and find hope in the fact that RNA editing is a solution for the future.


References

[1] “Darwin, Evolution, & Natural Selection.” Khan Academy, Khan Academy, http://www.khanacademy.org/science/biology/her/evolution-and-natural-selection/a/darwin-evolution-natural-selection.

[2] Nguyen , Anh. “CRISPR and the Jurassic World of Gene Editing.” The Student Scientist, 15 June 2018, thestudentscientist.org/2018/05/22/crispr-and-the-jurassic-world-of-gene-editing/.

[3] Olena, Abby. “Cephalopod Genomes Contain Thousands of Conserved RNA Editing Sites.” The Scientist, http://www.the-scientist.com/daily-news/cephalopod-genomes-contain-thousands-of-conserved-rna-editing-sites-31695.

[4] O’Neil, Dennis. “Basic Principles of Genetics: Mendel’s Genetics.” BASIC PRINCIPLES OF GENETICS: An Introduction to Mendelian Genetics, www2.palomar.edu/anthro/mendel/mendel_1.htm.

[5] Vlasits, Anna. “Science Reveals Yet Another Reason Octopuses and Squid Are So Weird.” Wired, Conde Nast, 3 June 2017, http://www.wired.com/2017/04/cephalopod-gene-editing/.

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