While scientists have traditionally turned to rodents when it comes to understanding the biology behind a particular condition, Sidra’s pioneering program is all based around one particular species of freshwater fish.
Genetic similarities
The zebrafish is a minnow species which gains its name from the blue stripes found on either side of its body. Commonly found in the waters of southeast Asia, it appeals to geneticists because humans and zebrafish
share 70 per cent of our genes.
“No one would imagine that a tiny fish from the Indian Ocean would be used in biomedical research,” says Dr Sahar Da’as, who leads the Sidra Medicine Zebrafish Facility. “But of the genes we have in common, 84 per cent are related to human disease genes.”
This isn’t as much as mice or indeed other mammals, but zebrafish do offer two crucial advantages.
Researchers can easily maintain several thousand fish in a small lab, while they develop remarkably quickly. Within 24 hours of being hatched as a single cell, they already have a head, tail, and a beating heart. By five days, they are fully formed and swimming around.
“Five days in the fish’s life is equivalent to nine months in humans, while that would be around 21 days for rats and mice,” says Da’as. “So within one week, we are able to give answers to patients.”
When any child with mysterious, unexplained symptoms – which can range from seizures to muscle wastage to a malformed skull – presents to doctors at Sidra, their genome is immediately sequenced and screened for known gene mutations.
If the patient is found to carry a particularly unusual mutation, one that scientists have never encountered before, they begin the process of attempting to replicate the biology in a zebrafish embryo.
