Young animals of the North American squid: In the animal on the right, the genes for the color of certain skin pigments are switched off
Photo: Karen CrawfordThe list of animals that researchers have already edited with the Crispr gene scissors is long: they include mice, monkeys have also been there, fruit flies and zebrafish. So far, the results have been of particular interest for basic research.
With Crispr, scientists have for the first time a tool with which they can switch off or change individual genes in the body cheaply, quickly and with great precision. This makes it possible to find out what role individual genome segments play in the development of diseases, the perception of pain or the development of the brain.
This manipulation has not yet worked with squids. Researchers working with Karen Crawford from the Eugene Bell Center at the University of Chicago report that they are particularly interesting for research into the nervous system and thus also with a view to diseases such as Alzheimer's and Parkinson's.
Problems with the needle
Cephalopods, which include octopuses, have the largest brains of any invertebrate and are considered to be very intelligent. The North American squid, with which Crawford is also experimenting, made research into nerve impulses possible in the 1950s. In 1963 the Nobel Prize for Medicine was awarded for this.
The relatively new and very precise Crispr gene scissors have not yet been used in molluscs. In order to switch genes on or off in all body cells of an individual, scientists have to change the genome of the animals in the embryonic stage and bring the gene scissors into a unicellular embryo. However, the squid embryos are surrounded by a sturdy shell.
The fine needles that professionals normally work with in such experiments always broke off. So Crawford developed tiny scissors with which she first cut a small hole in the embryo shell, through which a specially made quartz needle then passed, with which she could bring Crispr into the cell.
Incorporate phosphors into the genome
The team's first goal was to switch off a gene whose function it already knew. This is how you can check whether the scissors are working. The selected gene sequence called TDO controls the color of the eyes and certain pigments in the skin of the squid.
North American squids: They helped researchers win the Nobel Prize for Medicine
Photo: Roger HanlonIf Crispr changed the TDO gene so that the squid cells could no longer read the information it contained, animals with colorless skin emerged and the typical reddish spots had disappeared. The method was successful in more than 90 percent, the researchers write in a study from the end of July in the specialist magazine "Current Biology".
In the future, they want to use the technology to study more precisely how nerve cells control the body of squid. They also hope to gain knowledge for the further development of artificial intelligences and materials research, because squids can adapt their skin color to their surroundings.
However, Crawford and colleagues want to transfer their method to other cephalopod species first. The North American squid that was used in the current experiments is quite large for a laboratory animal at up to 50 centimeters. In addition, it has not yet allowed itself to be bred for several generations in captivity.
The researchers therefore now want to try to apply Crispr to the species Euprymna berryi as well. The small cuttlefish grow to a maximum of three centimeters and are easier to keep in the laboratory. It remains to be seen whether the new technique of inserting the gene scissors into the eggs will also work in the much smaller animals.
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