Chuck Bednar for redOrbit.com – Your Universe Online
Researchers from the US and Israel have identified the first-ever example of a creature capable of editing its own genetic makeup in order to blend into its surroundings – the squid.
Reporting in a recent edition of the journal eLife, Dr. Eli Eisenberg of the Tel Aviv University Department of Physics and Sagol School of Neuroscience and his colleagues explained that the Doryteuthis pealieii squid can alter most of its own proteins on an as-needed basis.
“We have demonstrated that RNA editing is a major player in genetic information processing rather than an exception to the rule,” explained Dr. Eisenberg, who co-authored the study along with researchers from the University of Connecticut Health Center, Bar-Ilan University in Israel, and the University of Puerto Rico Medical Sciences Campus.
“By showing that the squid’s RNA-editing dramatically reshaped its entire proteome – the entire set of proteins expressed by a genome, cell, tissue, or organism at a certain time – we proved that an organism’s self-editing of mRNA is a critical evolutionary and adaptive force,” he continued, adding that the discovery could also have implications for treating diseases in humans.
Although RNA is a copy of the genetic code that is translated into protein, its so-called transcript can be edited before it is translated into protein. This process can pave the way for different types of those proteins. Scientists have already observed instances of abnormal RNA editing in human patients with various neurological diseases, the study authors noted.
Squid and octopuses change their physiological appearances during the course of their lifetimes, as well as across different habitats. This suggested that extensive recoding might be taking place in those species, but that had never previously been confirmed as the genomes of these creatures (as well as those of most similar species) had yet to be sequences by scientists.
These scientists weren’t squidding around
In the new study, Dr. Eisenberg and his colleagues extracted both DNA and RNA from squid and used sequencing and computational analysis techniques to compare and contrast both types of genetic material. They identified those sequences in which the RNA and DNA did not match-up as having been edited by the creatures.
“It was astonishing to find that 60 percent of the squid RNA transcripts were edited,” Dr. Eisenberg said. “The fruit fly, for the sake of comparison, is thought to edit only 3 percent of its makeup.”
“Why do squid edit to such an extent? One theory is that they have an extremely complex nervous system, exhibiting behavioral sophistication unusual for invertebrates,” he added. “They may also utilize this mechanism to respond to changing temperatures and other environmental parameters.”
The study authors, who were recently given an Israel-US Binational Science Foundation grant to explore the subject of genetic editing in octopuses, hope to use their approach to identify recoding sites in other types of organisms who have yet to have their genomes sequenced.
“We would like to understand better how prevalent this phenomenon is in the animal world. How is it regulated? How is it exploited to confer adaptability?” said Dr. Eisenberg said. “There may be implications for us as well.”
“Human diseases are often the result of ‘misfolded’ proteins, which often become toxic,” he added. “Therefore the question of treating the misfolded proteins, likely to be generated by such an extensive recoding as exhibited in the squid cells, is very important for future therapeutic approaches. Does the squid have some mechanism we can learn from?”
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