The first genetically modified squid scientists are fascinated by a possible new way of studying marine animals, which are so strange that they are sometimes compared to other life forms.
Scientists report this week that they turned off a pigmentation gene in squid called Doryteuthis pealeii. Their success shows that cephalopods ̵1; which include squid and octopus – can finally be studied using the same genetic tool that allowed scientists to study the biology of more common laboratory animals such as mice and fruit flies. They are easy to keep in the lab, and scientists regularly modify their genes to get an idea of behavior, disease, and possible treatment.
Cephalopods may seem rather strange without scientists who are not interested in their genes. These rat creatures have huge intelligent brains that are not like our own. They travel by jet propulsion, and some can instantly change skin color. All this weirdness is why some biologists want to understand them better.
“They developed these big brains and this sophistication of behavior completely independently,” says Joshua Rosenthal, a researcher at the Marine Biology Laboratory in Woods Hall, Massachusetts. “It makes it possible to compare them with us and see which elements are common and which are unique.”
Until now, the study of cephalopods has prevented the fact that it was not possible to manipulate the genes of squid or octopus. Rosenthal is part of a group that is trying to change all that. The team gathers a wide range of exotic cephalopods – everything from the eagle cuttlefish to dwarf octopuses – to figure out how to keep them in captivity and change their DNA.
Researchers are also working with a well-known local squid that lives in the waters around Woods Deer. Historically, this squid has been important to neurobiologists because it has a giant, easy-to-study nerve cell. Much of what is known about how nerve cells send electrical signals comes from research on this cell, and this study led to the Nobel Prize in 1963. Moreover, scientists have traced the DNA that makes up the genetic code of this squid.
Every summer, a research boat leaves Woods Hole and collects squid, Doryteuthis pealeii. Karen Crawford of St. Mary’s College, Maryland, a key member of the research team, previously figured out how to take sperm and eggs from these squid and produce embryos in the lab.
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Based on this work, she and her colleagues found out how to introduce gene-changing materials into a fertilized egg to disrupt a gene involved in the color of squid skin and eye cells. The biggest problem was penetration through the hard outer layer that surrounded the early squid embryo, Rosenthal said.
“We’ll have needles to break for months,” he says. “So we figured out how to finally insert the injection needle. Finally, it turned out to be one of the biggest checkpoints in this study.”
As a result of squid hatching, there were far fewer small dark spots, which are usually characteristic of the species because the pigmentation gene was knocked out in almost every cell.
“For me, this changes in the game. I was interested in trying to understand how these animals work from the molecular level, so now we actually have the opportunity to go in and see what an individual gene does,” said Carrie Albertin, another member of the research team. who also works at the Marine Biology Laboratory.
It’s honest, if you asked me five years ago if we could do it, I’d just giggle and say, “I dream about it.” But, you know, I didn’t think it would be possible. “We’re here,” says Albertine.
This species of squid cannot be grown to maturity in the laboratory – it is too large. But there are many other, smaller species of squid and octopus, and the team is already working to pass the technology on to those raised in captivity. Researchers are also looking to add genes, not just knock out existing ones.
The work impressed other squid biologists, such as Sarah McAnluthy of the University of Connecticut. She studied the Hawaiian squid bobtail, and says that in the past, researchers have tried to genetically alter cephalopods.
“It’s amazing that they made it work, and it’s a huge step forward for cephalopod researchers around the world,” says McAntual. “We all have to put out bottles of champagne. It’s amazing.”
When biologists study natural squid, they end up “hitting something on the wall of understanding” because they can’t play with animal genetics to explore how its systems work at the most basic level, McAlty says. She believes that the ability to genetically modify cephalopods should make possible all sorts of new experiments.
“If I could do something, I’d start playing with the squid’s immune system completely,” says McAltil, to try to understand how, say, a Hawaiian squid bobtail knows it doesn’t attack the kind of glowing symbiotic bacteria that live inside it.