Scientists Modify Zebrafish Germ Line

A discovery by researchers at Purdue University may not sound all that exciting, but it could revolutionize genetic research.

Researcher Paul Collodi and his team developed a technique that allowed them to genetically modify cells they had removed from a zebrafish embryo. When they inserted the modified cells back into the embryo, they demonstrated that the genetic changes they made were present in the zebrafish’s germ line. When the embryo grows into an adult and breeds, the changes in its genome will be passed on to its offspring.

This is an incredible discovery because until now the only animal that germ line changes could be made to was the mouse. But using mice for this sort of research has a number of problems, not the least of which is the cost. The process with mice can end up costing thousands of dollars per mouse.

“With mice you have maybe a dozen embryos to work with,” Purdue’s Paul Collodi told Science Daily, “and you have to do surgery to transplant the embryos back into the mother. Compare that to the zebrafish embryo where we can modify 100 embryos an hour, and, because the embryos develop outside the mother, we don’t have to do surgery. The entire developmental phase takes only four days.”

With a little more refining of the process, genetically modified zebrafish could play a key role in the research that will occupy those studying the human genome — mapping how various genes work to produce specific proteins.

“With the human genome project they’re sequencing genes, and each of those genes causes the body to produce various proteins at different times,” Collodi said. “If you want to understand what the genes actually do, you have to study the function of the proteins they produce, and the zebrafish makes a nice model for that.”

The one hurdle that researchers still have to overcome is finding a way to prolong the length of time they can keep the zebrafish embryo cells in the lab before they have to reinsert them. Currently researchers have only been able to keep the embryo cells alive for a few days. They will need to find a way to keep them alive for several weeks in order to make the sort of genetic modifications that researchers will want to study.


Zebrafish could become genetics “lab rat” of choice. Science Daily, March 6, 2001.

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