Transgenic sheep and wool growth: possibilities and current status

Area of Science:

• Animal genetics
• Sheep transgenesis
• Wool fiber science

Background:

• Merino wool quality and performance improvements are ongoing goals.
• Sheep transgenesis enables study of wool keratin protein and fiber properties.
• Gene manipulation offers novel changes to wool fiber characteristics and growth.

Purpose of the Study:

• To establish an efficient sheep transgenesis program.
• To investigate wool keratin gene constructs for improved fiber properties.
• To enhance wool growth rate via increased cysteine supply to follicles.

Main Methods:

• Developed an efficient sheep transgenesis program achieving a 13% transgenic rate in lambs.
• Produced four live F0 transgenic sheep expressing a wool keratin type II intermediate filament gene.
• Generated transgenic sheep with cysteine synthesis genes using Rous sarcoma virus, mouse phosphoglycerate kinase, and sheep small proline-rich protein promoters.

Main Results:

• Transgenic sheep expressing a keratin gene showed phenotypic and ultrastructural fleece changes.
• One transgenic sheep produced low levels of cysteine in the rumen using the small proline-rich protein promoter.
• Cysteine production in the rumen was not detectable at 6 months of age.

Conclusions:

• Sheep transgenesis is a viable method for altering wool characteristics and growth.
• Further optimization is needed to enhance cysteine production for improved wool growth rates.
• The study demonstrates potential for genetic modification to improve wool production in sheep.