Handmade cloned transgenic sheep rich in omega-3 Fatty acids

PLoS One. 2013;8(2):e55941. doi: 10.1371/journal.pone.0055941. Epub 2013 Feb 20.

Abstract

Technology of somatic cell nuclear transfer (SCNT) has been adapted worldwide to generate transgenic animals, although the traditional procedure relies largely on instrumental micromanipulation. In this study, we used the modified handmade cloning (HMC) established in cattle and pig to produce transgenic sheep with elevated levels of omega-3 (n-3) fatty acids. Codon-optimized nematode mfat-1 was inserted into a eukaryotic expression vector and was transferred into the genome of primary ovine fibroblast cells from a male Chinese merino sheep. Reverse transcriptase PCR, gas chromatography, and chromosome analyses were performed to select nuclear donor cells capable of converting omega-6 (n-6) into n-3 fatty acids. Blastocysts developed after 7 days of in vitro culture were surgically transplanted into the uterus of female ovine recipients of a local sheep breed in Xinjiang. For the HMC, approximately 8.9% (n =925) of reconstructed embryos developed to the blastocyst stage. Four recipients became pregnant after 53 blastocysts were transplanted into 29 naturally cycling females, and a total of 3 live transgenic lambs were produced. Detailed analyses on one of the transgenic lambs revealed a single integration of the modified nematode mfat-1 gene at sheep chromosome 5. The transgenic sheep expressed functional n-3 fatty acid desaturase, accompanied by more than 2-folds reduction of n-6/n-3 ratio in the muscle (p<0.01) and other major organs/tissues (p<0.05). To our knowledge, this is the first report of transgenic sheep produced by the HMC. Compared to the traditional SCNT method, HMC showed an equivalent efficiency but proved cheaper and easier in operation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Chromatography, Gas
  • Clone Cells
  • Cloning, Organism / methods*
  • Fatty Acids, Omega-3 / metabolism*
  • Female
  • Helminth Proteins / genetics
  • Helminth Proteins / metabolism
  • Male
  • Microsatellite Repeats / genetics
  • Nuclear Transfer Techniques
  • Sheep / genetics*

Substances

  • Fatty Acids, Omega-3
  • Helminth Proteins

Grants and funding

This study was funded by the research grants from the China Ministry of Agriculture (2009ZX08008-005B) and the Chinese Academy of Sciences (KSZD-EW-005). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.