Spotlight

Jean Fleming Sheep Scientist

By Judith Doyle

Becoming part of an international network of scientists working on gene expression in sheep was a major benefit of a recent overseas study trip made by Dr Jean Fleming.

The trip came courtesy of British Airways as part of the first Zonta Science Award. The Wellington branch of the professional women's service club is keen to raise the public profile of women in science. The biennial prize has been approved by the Human Rights Commission to encourage women to remain in science careers.

"One of the delightful outcomes of the Zonta Science Award trip was to discover all these wonderful women working in the labs I visited in the United States, Scotland and France," Fleming said.

The lab visits involved Fleming's research into the fecundity gene in Booroola Merino sheep. The gene boosts the ovulation rate in Booroola ewes, resulting in a high lambing rate. If a genetic marker for the gene could be found, it could be tagged with other desireable traits, such as meat or wool quality or disease resistance.

Fleming gathered useful information on growth factor gene probes from Professor Marian Blum at New York's Fishberg Research Institute of Neurobiology. She exchanged ideas with Dr Judy McNeilly on the expression of pituitary hormone genes in sheep at Edinburgh's Institute of Animal Physiology and Genetics Research. Her visit to the Reproductive Physiology Laboratories in Nouzilly, France, has led to collaboration between the lab and Fleming's Wallaceville Animal Research Centre.

Fleming's objective is to establish methods to measure gene expression -- the process of turning on a gene and producing a protein. It's a new field and the lab visits have proved useful in gathering information. If gene expression can be measured, then direct comparisons can be made between animals with and without the fecundity gene. Central to this is the extraction and analysis of the messenger RNA, the intermediary between the gene and the protein.

"My role is to look at which genes are switched on and whether the presence of the fecundity gene causes the production of more hormone or not", Fleming said. "The quantitation of the small amounts of messenger RNA is right at the forefront of research at the moment and people are only just developing methods for doing it."

The Booroola Merino breed was developed last century by Samuel Marsden, from Merinos, Cape sheep and the Bengal breed. Studies have shown that the superfertility was genetic and that it came from a single gene or a closely linked set of genes.

"We think the fecundity gene is a fortuitous mutation coming from one of these early breeds that were crossed with the Merino," said Dr Fleming. "However, at the moment we cannot tell which lambs have the gene and which do not. We are desperately looking for a DNA marker. We are also interested in the mechanism by which the fecundity gene influences ovulation rate, as this may have implications in fertility control in humans."

Fleming came to sheep studies via a roundabout route. In Britain, she spent the 70s studying brain biochemistry, looking at genetic neurological diseases such as Huntingdon's Disease. On her retun to New Zealand, she worked on rat hormones and reproductive biochemistry. An MSc at Wellington Clinical School was followed by a PhD looking at how the hypothalamus controls hormone release from the pituitary.

"It's very rare that you ever do work on human tissue because -- obviously -- you can't get it readily, so I used the sheep as an animal model. I learned how to dissect the brain and all about the control of the reproductive axis through the brain. Within New Zealand there were perhaps a handful of scientists who knew their way around the sheep brain at that time."

Wallaceville researchers wanted to measure the brain hormone in Booroola Merinos that stimulates the pituitary to release the reproductive hormone. Fleming's experience made her the most appropriate person for the study. Study leave in Australia taught her how to analyse RNA. Since then she has set up a molecular biology laboratory at Wallaceville to look at gene expression in Booroola sheep.

Fleming hopes to have a method for quantitating the RNA for one pituitary hormone established by the middle of this year. Once achieved for one gene, it will be easier to set up a system for other genes.

Being able to examine how other labs around the world are tackling the problems in this very new field brings her goals and objectives that much closer, Fleming believes.

Judith Doyle is a freelance writer based in Wellington.