Dolphins are well-regarded as the most intelligent creatures in the ocean. However, the odd-looking cephalopods such as octopus, squid, and cuttlefish are giving the Einsteins of the sea a run (swim) for their money. More interestingly a recent study dictates that these creatures “don’t always follow the rules laid out in their DNA. Straying from prescribed genetic instructions may have increased the cephalopods’ thinking prowess, but comes at an evolutionary cost.” Researchers from The Cell report that “once genes have been copied from DNA into RNA, these cephalopods heavily edit the genes’ protein-making directions” which in turn results in different forms and functions than would be predicted. Although it sounds like a broad claim to state “all cephalopods” it should be noted researchers took care to involve one squid, two octopus, and one cuttlefish species in their study. Thus, their conclusions are applicable to a wide variety of cephalopods and their related species. The study found that between 80,000 to 130,000 RNA sites had been edited, a very large number when contrasted with the minuscule 1,159 RNA edited sites and 933 edited sites in a nautilus and mollusk, respectively. On a molecular level researchers discovered “RNA editing changes one of the information-carrying subunits of RNA from the nucleotide adenosine to one called inosine. That substitution can change how a cell reads the genetic instructions to build proteins, exchanging one amino acid for another not specified by the DNA instructions.” Although such tweaks to proteins usually produce harmful effects, and evolution tends toward the occam's razor principle of simplicity, cephalopods seem to not follow the trend. As juxtaposition “in the brains of humans and other mammals, fewer than 1 percent of RNA editing sites change protein-coding instructions.” However, computational biologists Noa Liscovitch-Brauer and Eli Eisenberg of Tel Aviv University in Israel and colleagues have discovered that “squid, octopus and cuttlefish edit about 11 to 13 percent of the protein-building RNAs in their brains...cephalopods edit RNA in other tissues, too, but not as much as in the brain.” The findings are complex and much remains unknown. Eisenberg has stated “adding up all the edited and unedited combinations could produce hundreds to thousands of different versions of a protein within a cell. It introduces immense complexity and diversity.” Speculation still flourishes as scientists try to discover why the species edit RNA in the same place, but the commonality among species proposes such edits to be an important facet in cephalopod evolution.
This article and its premise of the discovery of the cephalopod tendency to edit their RNA at first seem unimportant and perhaps random to the unenlightened human. However, when looking more deeply at what evolutionary factors caused the cephalopod brain to develop while their bodies did not can tell us more about evolution and its application to humans. Science is a constantly evolving field, changing and growing at every angle. New discoveries about these cephalopods may encourage or inspire other scientists to look more into human RNA editing. We may discover more about our evolutionary history and how we wound up with such a vastly more developed brain than most creatures here on earth. Evolution of any species, including the unassuming cuttlefish, is integral to our understanding of ourselves and the world around us.
Overall the author of this article, Tina Hesman Saey, did an excellent job. I particularly enjoyed her inclusion of relevant graphs and images. These more qualitative touches made the article more accessible and understandable for the average reader. Additionally, I commend her for her use of quotes as well as her evident in-depth research about the topic. By including the ideas and point of views of many leading researchers on the topic Saey asserts a sense of authority and intellectual exploration of the complex issue. However, there was one aspect upon which Saey could improve. Primarily, I would have appreciated greater in-depth commentary and relevance on her part. The article felt more like a reiteration of the facts rather than a piece of science journalism with new ideas and points of view. Her article demonstrates the balance between research and your own thoughts. It is a small tightrope to walk between infusing your piece with your ideas as well as staying true to the facts. In the future I would recommend Saey fix her problem by dedicating a specific paragraph somewhere in her article where she uses no quotes, only her own commentary, to assert why her article is relevant and should be discussed.
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