Quick Dips

Charting Chromosomes

AgResearch geneticists are finding that they are becoming accepted as world authorities on the gene-mapping of sheep.

This careful analysis of chromosomes to identify and locate individual genes is of great importance in understanding the way characteristics are inherited in a species. The New Zealanders have found themselves a specialised niche in an expanding field.

Drs Grant Montgomery and Tom Broad were recently in England to discuss with other researchers the possibility of a mammalian genetic database. Studies of many different species are currently under way, and the sharing of results between studies is useful because genes often perform the same function in different species. Knowing their location in one case gives a pointer to likely locations in other cases.

"By looking at the maps of other species, I can now plan my own mapping work more efficiently," says Montgomery. "Comparative mapping allows the advantages of these diverse species to be shared, as well as providing information on evolutionary relationships and rates of change."

A practical application of manipulating the inherited characteristics of sheep is growing out of another area of research. A new specialty product, ultra-fine wool, appears a promising option for sheep farmers, judging by current results from a collaboration between AgResearch Tara Hills and a group of high country farmers.

Ultra-fine wool is ideal for the up-market clothing industry. It produces a more luxurious end product than normal wool, and there is a strong demand. Four years ago, over 45,000 Merino ewes were screened for fibre diameter, with the top one percent pooled to form an elite flock for a breeding programme aimed at producing sheep with finer than normal wool.

The outcome seems to have been successful. Fibre diameters in the fine-wool flock are some two microns lower than in a control flock, yet fleece weights and yields are similar. Researchers also predict that the fibre will contine to become 0.1-0.2 microns finer in each new generation.