The Zebrafish

This image is courtesy of Sarah Farrington of the Center for Cancer Research at MIT. It comes from the home page of ZFIN ("Zebrafish Information Network"):

The zebrafish, Danio rerio, has become another popular "model" organism with which to study fundamental biological questions.

It is a small (1–1.5 inches)(2.5–3.8 cm) freshwater fish that grows easily in aquaria (it is available at many pet stores).

Some of its advantages for biologists:

"Forward" and "Reverse" Genetics


Since Mendel's time, most genetics has involved

So this "forward" genetics proceeds from phenotype -> genotype.

Some examples in these pages:

These methods have been called "forward" genetics to distinguish them from a more recent approach, which has become an urgent priority with the successes of genome sequencing.


Rapid methods of DNA sequencing has generated a vast amount of data.
List of some of the organisms whose complete genome has been sequenced.
Thousands of suspected genes have been revealed (e.g., finding open reading frames — ORFs), but the function of many of them is still unknown.

But now with

So this "reverse" genetics proceeds from genotype -> phenotype.

Reverse genetics has been applied successfully to

For example, the function of a mysterious gene sequence in Danio can be studied by

Links to other examples of how this technology is used in reverse genetics.

Because we share so many similar gene sequences (orthologous genes) with Danio, if one can discover the function of the gene in Danio, then we have a better idea of the role of its ortholog in humans.

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18 December 2020