Transparent Zebrafish to Aid in Cancer Research

Newest statistics show cancer deaths are decreasing in the US. This appears to be a sign of great progress in the fight against cancer. Still, daily over one thousand Americans are killed by this terminal disease. Therefore, scientists battle on and look for new ways to improve cancer prevention, diagnosis, and treatment methods. At stake is not only the honor to be the first to find an effective treatment or even prevention method, but also big profits. One major obstacle in the battle against cancer is the difficulty to visually observe tumor development and treatment effects. Dissection of animal test subjects is widely used. In order to avoid dissection and study tumor growth and treatment effects in living organisms, researchers have entered a race in the breeding of transparent living organisms. In October 2007 scientists at the Institute for Amphibian Biology at Hiroshima University in Japan already announced the successful breeding of transparent frogs (AC reported). Now scientists at Boston's Children's Hospital have successfully bred a transparent zebrafish for study purposes.

Animal rights activists have already for a long time criticized the dissection of animals for research purposes and suggested computer models instead. Now they will have a little less to complain about. The development of transparent living organisms for research purposes will provide scientists with a cheap and cost cutting research tool. They are able to look through the skin of a living organism and observe the organ, blood vessel, and reproductive organ development without the need for dissection. Scientists can more effectively study what might lead to the development of cancerous cells and how tumors grow and develop. They will be able to literally see the effects of treatment methods and in the long run device more effective treatment, diagnosis, and prevention techniques.

The Japanese scientists at the Institute for Amphibian Biology at Hiroshima University in Japan announced in October 2007 that they successfully bred a transparent frog. However, the frog program is still in its infancy and the process of breeding transparent frogs has yet to be perfected. While the transparent frogs remain transparent into adulthood, only one-sixteenth of a bred frog generation actually turns out to be transparent. As of now, the transparency is not inherited by a viable next generation of frogs. The researchers primarily identify poor egg development as the culprit. Once the process is perfected they will seek to patent their transparent amphibians.

This means the race is on to develop transparent living organisms and to patent the invention as quickly as possible. Big bucks are at stake. The first to develop a valid and durable prototype will be able to provide the scientific world with an effective research tool while patent laws exclude others from doing the same.

Besides the Japanese scientists at other institutions around the world have experimented with the breeding of transparent living organisms. And now scientists at Boston's Children's Hospital under the lead of Richard White, MD, PhD, succeeded in breeding a transparent zebrafish. Zebrafish should actually be better research subjects, as their genetic make-up is similar to that of humans. Therefore, scientists deem them to be good models for human diseases. Like the transparent frog, the transparent zebrafish is transparent throughout life, providing researchers with the opportunity to view internal organs and blood vessels from outside the fish over the life of the organism. The scientists intend to study disease processes like tumor growth and development as well as treatment methods like the engraftment of bone-marrow transplants in this living organism.

The transparent zebrafish was bred by mating two existing breeds of zebrafish, "roy orbison" and "nacre". Zebrafish normally have three pigments in their skin, which are reflective, black, and yellow. The "roy orbison" variety does not have reflective pigments. The "nacre" kind does not have black pigments in their skin. After these two breeds were mated, the offspring turned out to have yellow-pigmented skin, which is clear and allows for observers to view the inside of the fish. The new breed has been named "Casper."

Unlike the transparent frog program, the zebrafish breeding program proves to be more reliable in producing viable transparent offspring. With the zebrafish being closer in their genetic make-up to that of humans, the scientists at Boston's Children's Hospital have made a giant leap forward in the utilization of this type of research tool.