Inshore squid hatchlings (Doryteuthis pealeii). On the left is a control pup; note the black and reddish brown chromatophores evenly placed on its mantle, head and tentacles. In contrast, the embryo on the right was injected with CRISPR-Cas9 targeting a pigmentation gene (tryptophan 2.3 dioxygenase) prior to first cell division; It has very few pigmented chromatophores and light pink to red eyes. Credit: Karen Crawford
A team from the Marine Biology Laboratory (MBL) accomplished the first gene deletion in a cephalopod using squid Doryteuthis pealeii, an exceptionally important research body in biology for nearly a century. The historical study, led by MBL Principal Scientist Joshua Rosenthal and MBL Scientist Whitman Karen Crawford, appears in the July 30 issue of Current biology.
The team used the CRISPR-Cas9 genome edit to remove a pigmentation gene in squid embryos, which removed pigmentation in the eyes and skin cells (chromatophores) with high efficiency.
“This is a critical first step towards the ability to remove (and delete) genes in cephalopods to address a number of biological questions,” says Rosenthal.
Cephalopods (squid, octopus, and cuttlefish) have the largest brain of all invertebrates, a distributed nervous system capable of instant camouflage and sophisticated behaviors, a unique body plan, and the ability to widely recode their own genetic information into messenger RNA, along with other distinctive features. These open many avenues for study and have applications in a wide range of fields, from evolution and development, to medicine, robotics, materials science, and artificial intelligence.
The ability to remove a gene to test its function is an important step in the development of cephalopods as genetically treatable organisms for biological research, increasing the handful of species that currently dominate genetic studies, such as fruit flies, fish zebra and mice.
Doryteuthis pealeii, often called the Woods Hole squid. Studies with D. pealeii have led to important advances in neurobiology, including the description of the fundamental mechanisms of neurotransmission. The Marine Biology Laboratory collects D. pealeii from local waters for an international community of researchers. Credit: Roger Hanlon
It is also a necessary step to have the ability to generate genes that facilitate research, such as genes that encode fluorescent proteins that can be imaged to track neuronal activity or other dynamic processes.
“CRISPR-Cas9 worked very well in Doryteuthis; It was surprisingly efficient, “says Rosenthal. Far more challenging was delivering the CRISPR-Cas system to the single-celled squid embryo, which is surrounded by an extremely tough outer shell, and then raising the embryo through hatching. The team developed micro- scissors to trim the surface of the egg and a beveled quartz needle to deliver the CRISPR-Cas9 reagents through the clip.
Studies with Doryteuthis pealeii They have led to fundamental breakthroughs in neurobiology, beginning with the description of action potential (nerve impulse) in the 1950s, a discovery by which Alan Hodgkin and Andrew Huxley became Nobel Prize winners in 1963. For decades D. pealeii It has attracted neurobiologists from around the world to the MBL, which collects squid from local waters.
Rosenthal and colleagues recently discovered extensive recoding of mRNA in the nervous system of Doryteuthis and other cephalopods. This research is in development for possible biomedical applications, such as pain control therapy.
D. pealeii However, it is not an ideal species to develop as a genetic research organism. It is large and takes up a lot of space in the tank and, most importantly, no one has been able to grow it through multiple generations in the laboratory.
For these reasons, the next goal of the MBL Cephalopod program is to transfer the new elimination technology to a smaller cephalopod species, Euprymna berryi (the hummingbird squid), which is relatively easy to grow to produce genetic strains.
The mysterious and legendary genome of the giant squid is revealed
Current biology (2020). DOI: 10.1016 / j.cub.2020.06.099
Provided by the Marine Biology Laboratory
Citation: First genetic knockout in cephalopods achieved (2020, July 30) retrieved on July 31, 2020 from https://phys.org/news/2020-07-gene-knockout-cephalopod.html
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