In the world of medicine, research on embryonic stem cells offers the possibility of curing fatal and debilitating diseases. In the world of aquaculture, embryonic stem cell research may enhance production and reduce environmental risks.
With funding from Illinois-Indiana Sea Grant, a team of Purdue University scientists have developed fish embryonic stem cell lines that can potentially be used to modify the genetic characteristics of any fish species. Paul Collodi and his team established these cultured cells from zebrafish that can form viable eggs or sperm when transplanted into an embryo. The cells may be used in the future to introduce specific alterations into the fish chromosomes.
One of the ultimate goals of this research is to use these cell lines to grow fish that are lacking the hormone necessary for fertility (which can be reversed by adding the hormone to the fish’s diet). Controlling fertility in aquaculture production offers a way to reduce the threat of non-native species escaping and disrupting the balance of local waterways. A prime example of an invasive species escaping from aquaculture production is Asian carp. These fish have moved up the Mississippi River and pose a threat to the Great Lakes.
“If this technology is successful, it also offers many possibilities of enhancing aquaculture production through the manipulation of specific desirable genes. In an aquaculture setting, we may be able to control growth, disease, and reproduction rates, or change species characteristics and improve survival capabilities,” said Collodi. “Zebrafish possess a number of characteristics that make them ideal for developing this technology, including that they are relatively inexpensive and easy to maintain in the laboratory, but once we successfully develop gene-transfer methods, they will be applied to commercially important species.”
“This work may also have implications for research into the genetic basis for human disease and the development of new drugs,” said Collodi. “We are doing very basic research into gene function during embryonic development, which may offer insight into developmental abnormalities and help pinpoint which genes play a role in disease.”
This project has involved a series of difficult steps. First, the scientists developed a technique to grow zebrafish embryonic cells in a culture dish long enough to be practical for genetic research. Stem cells have the ability to develop into any kind of tissue, which makes them particularly useful for introducing genetic alterations. For example, it is critical that when these cells are transplanted into a host embryo, they have the ability to differentiate into sperm or egg, providing the means to pass on the altered trait.
The next step was to make specific genetic alterations in embryonic stem cells and to isolate these altered cells in a culture dish. The researchers used a red fluorescent protein gene as a way of identifying these cells. Now Collodi’s team is working to transfer the selected cells that carry the genetic alteration back into an embryo to produce fish with the altered trait. “We are using pigmentation pattern to determine if the embryonic stem cells contributed to the germ line of the host embryo and the genetic alteration was transferred to the next generation,” he said.
Collodi now has funding from the USDA and the National Institute of Health to continue this work. “The initial support from Illinois-Indiana Sea Grant allowed our lab to generate this promising data that has led to much larger funding opportunities,” he added.
The Illinois-Indiana Sea Grant College Program is one of more than 30 National Sea Grant College Programs. Created by Congress in 1966, Sea Grant combines university, government, business and industry expertise to address coastal and Great Lakes needs. Funding is provided by the National Oceanic Atmospheric Administration (NOAA), U. S. Department of Commerce, the University of Illinois at Urbana-Champaign and Purdue University at West Lafayette, Indiana.