| Chinese scientists announced Tuesday that they have successfully developed a technique which could lead to the breeding of transgenic sheep in large numbers.
Dr. Liu Mingjun with the Xinjiang Academy of Zootechnical Science said that the technique called "lentivirus " was more efficient and predictable than traditional methods, and could give China the edge for breeding genetically altered sheep and establishing a new transgenic sheep species.
Between February and April, 118 pregnant ewes carrying transgenic embryos delivered 162 lambs under the auspices of Liu's team. Of the new born, 92 were transgenic lambs, setting a record high transgenic efficiency rate of 56.8 percent.
By contrast, the transgenic efficiency -- proportion of transgenic lambs to the testing of newly born -- of traditional techniques ranged only from one percent to five percent on average.
Previous publications showed that the scientists of Roslin Institute of Edinburgh University made seven transgenic lambs with somatic cell cloning in one experiment, with an efficiency of 2.25 percent.
Liu said that his research team had for two years been doing transgenic experiments including cloning genes related to muscle- and wool-growth.
Last Autumn, the research team employed the innovative lentivirus technique to have 473 transgenic embryos transferred into 255 ewes. And 118 ewes got pregnant.
Liu said that the technique would require scientists to inject the cloned exogenous genes related to muscle- and wool-growth into lentivirus vectors.
The vector, a molecule invisible to naked eyes, can facilitate the integration of the desired genes with the host chromosome and thus improve the success rate of transgenic breeding, he said.
So far, 61 of the 92 transgenic sheep have survived.
Since American scientists gained the world's first transgenic sheep through microinjection in 1985, scientists from developed countries including the United Kingdom and Canada have been using transgenic techniques to cultivate new sheep species.
Liu said that his research aimed to strengthen sheep's muscle growth and increase the productivity and quality of sheep wool.
"The next thing we will do is to monitor the growth of the transgenic sheep, and conduct in-depth analysis and examination to screen out the best animals for the cultivation of a new species," he said.
A key premise to the cultivation of a new species, Liu said, was to obtain a stable and efficient transgenic technique.
To more easily track the transfer of the target genes, the research team also launched a separate experiment during the same period using green fluorescent protein gene as the genetic change marker.
A total of 11 new borns have been found to carry the marker gene. When put under ultraviolet lights, eight of them could be seen as displaying a clear green light on the nose, skin and hooves.
"It indicates that the marker gene has been effectively expressed," said he. |
