Media

• Publications
• Latest News

Using tropical fish to understand colour vision

It is hard to believe that tiny, striped tropical fish could help us to understand the causes of eye disease. UCD Conway scientist, Dr Breandan Kennedy explained how these fish do exactly that to a packed audience of transition year students during a recent Science Alive outreach seminar.

The fact that the genetic code of humans and zebrafish is similar is pivotal to the research carried out by Dr Kennedy, a senior lecturer in the School of Biomolecular & Biomedical Science, and his team.

He told his audience that zebrafish are an ideal organism to use as a model to study disease. They produce large numbers of offspring outside of the mother’s body that mature within three to four months. Their eyes develop rapidly; being present after 24 hours and functioning within five days. 

The audience could easily identify with the comparison of the morphology of the human eye to a camera and the functionality to a mobile phone; the lens changes shape to focus light on the retina; photoreceptors called rods and cones sense the light in the retina and produce a message that is conveyed via the optic nerve to the brain for display.  

There are many types of diseases that affect the eye. Some result in total or partial blindness. Those individuals who cannot read the first letter in a standard eye test are deemed clinically blind; having 20/200 vision. The ability to read the last line of this listing gives the perfect 20/20 vision score.

Cataracts and infection are treatable diseases of the eye while retinal degeneration and eye damage resulting from diabetes cannot be treated currently. Developing drug treatments depends on answering key questions; which cells are not working, which genes are defective and which drugs are beneficial.

Breandan Kennedy focuses on the genes that are defective in eye disease. He explained how the research carried out by his team identified the Rx gene, which when missing causes zebrafish and humans to have no eyes. By replacing this gene, the offspring of these fish had normal eye development.  

Students were curious as to how scientists can check whether a fish is blind. Dr Kennedy explained that the zebrafish are placed in a drum of water. This drum has vertical stripes on the inside wall. He showed a movie clip of the zebrafish while the inner drum wall was being rotated. The eyes of one fish flickered as it saw and followed the movement of lines while those of another fish stayed still.

Podcast - 'Using tropical fish to understand colour vision'