Over The Horizon

Yac, Yac, Yac

When molecular biologists talk about YACs, the subject under discussion is not four-legged hairy ox-type animals, but Yeast Artificial Chromosomes used in gene mapping.

AgResearch Molecular Biology Unit scientist Dr Murray Broom has just returned from the US where he helped set up a YAC library to assist cattle gene mapping.

YACs are a resource needed to map genes of any species. It involves cutting up the DNA of any species into large pieces, and modifying this DNA to resemble a yeast chromosome. This foreign DNA is put into a yeast which then accepts it as its own. YACs are used to dissect particular regions on the animal's chromosome.

Libraries of different DNA pieces important to gene mapping are built up. AgResearch has a YAC library of 40,000 clones of different pieces of sheep DNA, which give the necessary coverage of the sheep genome. They're valuable for finding genes that are responsible for production traits such as lean growth, high fleece weight and disease resistance.

Sharing information on genomes is an essential way of building knowledge on the genes of all species, including humans.

Broom spent three months working with department scientists in Nebraska, setting up a YAC library and training staff in YAC production techniques to help cattle gene mappers in finding production genes of interest.