S T A N F O R D M E D I C I N E

Volume 17 Number 3 FALL 2000

On the Cover

Admitting Women to Medical School for More than a Century. 

Cover illustration by Janet Woolley.

Stanford Medicine, published quarterly by Stanford University Medical Center, aims to keep readers informed about the education, research, clinical care and other goings on at the Medical Center.

 

  

For the special section for Alumni, click on the link below:
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ping pong with a zebrafish

HOW A MODEL ORGANISM CAN EXPLAIN WHAT

BECAUSE MODEL ORGANISMS ARE ALL DERIVED FROM THE SAME TREE OF LIFE THAT PRODUCED HUMANS, MANY OF THESE CREATURES' GENES AND PROTEINS ARE SIMILAR TO OUR OWN. The primitive yeast, which last shared an ancestor with humans many millions of years ago, has fewer genes in common with modern humans than the zebrafish does, yet many genes in all three species are recognizably related and the proteins that they encode carry out the same functions within a cell.

Using model organisms, researchers can apply the "ping-pong" approach -- bouncing between data from humans and animal models -- to figure out the function of an unknown human gene. Here's how it works: A researcher with the sequence of a human gene in hand, scans databases of the DNA sequences of model organisms, looking for a similar gene. If the researcher locates an equivalent gene, let's say in zebrafish, he or she will likely be able to learn the gene's function -- because this information is noted in databases as well. Then, by inference, the human geneticists can quickly assign a function to the unknown human gene.

Similarly, researchers can take a handful of zebrafish genes with known functions and scan the human sequence for their counterparts. A match quickly reveals the location and function of human genes that were previously hidden among the millions of DNA letters that comprise the genome. KRISTIN WEIDENBACH

Related story:
Zebrafish: A Model for Life