Squid’s nerve fiber has been used in research for decades. But recently, researchers found out that editing squid genomes could pave the way for a more complete understanding of the nervous system and also unlock mysteries of the brain. Squids have a highly developed nervous and sensory system with complex brains and eyes. The Longfin inshore squid, a species of the loliginidae squid family, has been an important organism in neuroscience research. Its giant axon, nerve fiber, is essential for research. The axon is long in diameter and it carries the signal throughout the body
Last year, this study took a major step after a group of neuroscience students successfully used CRISPR-Cas9, a gene-editing tool to disable or knock out a gene in the Doryteuthis squid, a talented group of mollusks, Cephalopods, a small squid that belongs to the loliginidae family. This experiment led the researchers to investigate the genetics behind the cephalopods’ abilities, from color-changing cells to mating behavior.
The giant fibers were discovered in 1936, initially, the scientists thought they were blood vessels. From then the researchers began using them for experiments on the electrical and chemical mechanisms of the nervous system and the brain. The squid axon was so big that the scientists could attach electrodes to it and zap it. Many scientists even call the giant squid axon “Nature’s gift to neuroscience.” The study of squid nerves has bagged two Nobel Prizes and also resulted in hundreds of scientific papers. The first Nobel Prize was awarded to Alan Hodgen and his student Andrew Huxley in 1963 for revealing how nerves transmit electrical communication with other cells. The second Nobel prize was awarded in 1970 for elucidating the role of neurotransmitters.
The human genome consists of about 3.2 million bases or letters whereas a squid’s genome has 4.5 billion letters and half of it are made up of repetitive sequences. Sequencing those letters is like piecing an enormous puzzle together that depicts any empty blue sky, says Albertin, senior research scientist. After a massive effort to sequence and fit those billions of fragments of squid DNA form like a curveball. Doryteuthis squid’s eggs have a thick rubbery outer layer which is difficult to puncture by the fragile needles. These needles are used to inject the molecular editing tool CRISPR- Cas9 into the egg. The CRISPR-Cas won’t reach its target if the needle doesn’t puncture far, on the other hand, if the egg won’t develop if the needle punctures too far.
After much trial and error, scientists have experimented with knocking out the genes. Scientists also have focused on adding a gene to the squid to produce a protein. This protein fluoresces green when it binds to calcium and it also flows into the axon. This pigmentation knockout allows researchers to watch nerve development, so they begin working in a transparent squid. Leonid Moroz, a neuroscience major with UF health sums up the research, he says that with the combination of neural complexity and evolutionary distinctiveness, any basic research on cephalopods will speed up our understanding of the brain and it also helps to unlock mysteries of the brain.