Octopuses and squid have confirmed their reputation as Earth-bound “aliens” with the discovery that they can edit their own genetic instructions.
Unlike other animals, cephalopods – the family that includes octopuses, squid and cuttlefish – do not obey the commands of their DNA to the letter.
Instead, they sometimes interfere with the code as it is being carried by a molecular “messenger”. This has the effect of diversifying the proteins their cells can produce, leading to some interesting variations.
The system may have produced a special kind of evolution based on RNA editing rather than DNA mutations and could be responsible for the complex behaviour and high intelligence seen in cephalopods, some scientists believe.
RNA, a close cousin of DNA, is used to transfer software-like instructions from the genes to protein-making machinery in cells.
Scientists discovered that more than 60 per cent of RNA transcripts in the squid brain are re-coded by editing. In other animals, ranging from fruit flies to humans, such re-coding events only occur a fraction of 1 per cent of the time.
Similar high levels of RNA editing were identified in three other “smart” cephalopod species, two octopuses and one cuttlefish.
The mechanics of cephalopod RNA editing are still being investigated.
“When do they turn it on, and under what environmental influences? It could be something as simple as temperature changes or as complicated as experience, a form of memory,” says Joshua Rosenthal, lead author from the Marine Biological Laboratory at Woods Hole, US.
Octopuses and other cephalopods have a number of characteristics that have caused experts to compare them with aliens, including instantaneous colour-changing camouflage, blue blood, and an ability to see polarised light.
Journal reference: Cell, DOI: 10.1016/j.cell.2017.03.025