April 7, 2017
by John Hopton
Octopuses have a good change of being among the world's most interesting creatures, and newly published research adds weird evolutionary habits to their noteworthy features.
Evolutionary changes that benefit an organism tend to occur at the start of the molecular production process, with mutations in DNA being transcribed into RNA before being translated into an altered protein. For cephalopods, however, this is not the case. (We should mention that there are of course other cephalopods and not only octopuses - squid for example. They're interesting too. In a tasty sort of way).
In cephalopods, proteins can be altered without there previously having been any alteration of the basic sequence of the DNA blueprint.
The study, published in the journal Cell, also hints that squid and octopuses may be of greater evolutionary age than previously believed.
by John Hopton
Octopuses have a good change of being among the world's most interesting creatures, and newly published research adds weird evolutionary habits to their noteworthy features.
Evolutionary changes that benefit an organism tend to occur at the start of the molecular production process, with mutations in DNA being transcribed into RNA before being translated into an altered protein. For cephalopods, however, this is not the case. (We should mention that there are of course other cephalopods and not only octopuses - squid for example. They're interesting too. In a tasty sort of way).
In cephalopods, proteins can be altered without there previously having been any alteration of the basic sequence of the DNA blueprint.
The study, published in the journal Cell, also hints that squid and octopuses may be of greater evolutionary age than previously believed.
Unusually stable DNA
The unusual process of changing proteins without changing DNA is referred to by the researchers as 'RNA editing'.
Scientific American explains that: RNA editing...involves enzymes swapping out one RNA base (or nitrogen-based “letter” in the RNA/DNA alphabet) for another, presumably in the interest of an organism adapting to its environment."
Such editing is found in other creatures, including humans, however, it is very rare. Only a few dozen sites among some 20,000 genes in humans can be identified as doing something like this.
In cephalopods, though, the process is very common and is used in part to respond to changes in the temperature of the ocean.
Squid have roughly the same number of genes as humans, yet more than half undergo RNA editing. The editing happens particularly in the nervous system of a cephalopod, including in gene coding for ion channels that assist in electrical communication between neurons.
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