Why Zebrafish?

It turns out that the zebrafish is a superb animal for studying development. First, like humans, fish are vertebrates. Second, unlike humans, fish cheerfully mate with almost any other individual of the same species. Third, also unlike humans, fish embryos develop outside the mother- in a petri dish for example- and they develop very rapidly. As a further convenience, the embryos are transparent for the first couple of days of life, so watching them develop is as easy as watching a movie.

Just five days old, this zebrafish is entirely self-sufficient.

Here is what the fish looks like at five days of age. It is a small but perfect little fish. It is mature enough to go hunting. It can catch prey and eat it. From a single cell to this fish, in just five days. It makes you wonder, compared to this fish, what did you accomplish in the last five days?

How do you get your hands on the genes that make this happen? To do that is the goal of the research in my lab. How many genes do you need to get to a five-day-old fish? We already have a rough answer to this very interesting question.

A zebrafish is probably almost as complicated as a human. So, we imagine that fish, like humans, probably have about 30,000 to 50,000 genes. We have reason to believe that most of the time, if I take away one gene, nothing happens! The fish will develop normally most of the time. Only about 2400 genes are essential to development. Take any one of those 2400 away and something goes wrong. You end up with a dead or dying baby fish. It is like a birth defect.

The goal of the research in my lab is to isolate as many of these 2400 genes as we can and figure out how they work. Together, these genes contain the instructions for making a complete baby vertebrate animal. This is the mystery of development! Of life!
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Photos: Hopkins' Lab, MIT