Genetically Designed Sheep

By Jerilyn Watson

This is Steve Ember with the VOA Special English SCIENCE REPORT.

A research company in Scotland says it has produced two young sheep from sheep cells containing specially designed genetic material.

The publication Nature reported the research. It was done by PPL Therapeutics PLC, a company with headquarters in Edinburgh. The company helped produce Dolly, the first cloned sheep, in Nineteen-Ninety-Seven.

PPL scientists created the two baby sheep by placing genetic material in a special place in sheep cells. Then they united these specially changed cells with sheep eggs. The nuclei had been removed from the eggs. This process of cell changing and cloning produced the two baby sheep with the genetic changes. Tests of the two lambs showed the genetic changes were successful.

The process was difficult, however. The changed genetic material had to be placed correctly within extremely small chromosomes for the changes to succeed. Only fourteen lambs were born from more than four-hundred embryos. Tests showed that thirteen of the lambs had the right gene in the targeted area. However, all but two of the lambs later died. One of the genetically changed lambs had a gene added. This gene directed her body to produce a protein useful for treating the human lung disease emphysema. The lamb produced large amounts of the protein in her milk.

The researchers' success with the two lambs may help them produce genetic changes in other large animals. It may permit scientists to turn off unwanted genes in animals. The success also may help PPL in its efforts to create pigs with special organs. These organs could be placed in humans suffering from failure of their hearts, kidneys or other organs. The process used to produce the lambs could help make pig organs more similar to those of humans.

People suffering organ failure often die because there are not enough human organs that can be placed in them in a transplant operation. PPL scientists say producing pigs with organs similar to human organs could help solve that problem.

The process also could help scientists turn off an unwanted gene in pigs and other animals. This gene causes the human body to reject an animal organ received in a transplant operation.

This VOA Special English Science Report was written by Jerilyn Watson. This is Steve Ember.