What is Mitochondrial DNA and What Role Does it Play?

Posted by on Thursday, November 16th, 2017 in General

In the cloning process, we utilize oocytes, or unfertile eggs, from a commercial source. These oocytes are enucleated, meaning the nuclear DNA is removed and discarded. A cell from the genetic donor’s cell line or Genetic Preservation, which contains the nuclear DNA of the genetic donor, will be inserted into the enucleated oocyte to ultimately make a cloned embryo.  This process is repeated for all mammalian species that we  clone as part of the Somatic Cell Nuclear Transfer (SCNT) or cloning process.

In the cytoplasm of the enucleated oocyte or unfertile egg, there are organelles called mitochondria (mtDNA). Mitochondria are part of the cellular machinery that makes up cellular biology i.e. the powerhouse of the cell. The mitochondrial DNA is located in the mitochondria of the cell. The following are the key points in understanding mtDNA:

  • The mitochondrial genome is extremely small when compared to the nuclear genome of an individual. The nuclear genome contains approximately 3 billion base pairs of DNA; the mitochondrial genome contains approximately 17,000 base pairs of DNA. The small number of genes in the mitochondrial genome is highly conserved in mammals.
  • Nuclear DNA is contributed by equal numbers of chromosomes from the sire and dam (half of the DNA is from the sire, half of the DNA is from the dam). The mtDNA is only contributed from the dam. This mtDNA contribution comes for the ovum (egg) produced by the dam.

o The mtDNA of the cloned male is not passed on to its progeny because sperm contains only small amounts of mtDNA that does not enter the egg or oocyte of the female. This means the use of cloned males has no impact on the mtDNA of their progeny and the progeny will carry the same nuclear DNA contribution as the genetic donor.

o The mtDNA of the cloned female may be influenced by the oocyte that is used to create the cloned embryo or it may not be if the mtDNA haplotypes are the same. The female will carry the same nuclear DNA contribution as the genetic donor.

  • From the scientific studies in livestock, using large populations, differences in performance traits have not been shown as the result of differences in mitochondrial DNA (mtDNA) source. (Van Vleck LD, KJ Hanford, and SD Snowder, 2005).

For more information on ViaGen and their cloning technology, or if you have other questions about cloning,  simply call 1-888-8ViaGen or view their website at www.viagen.com.

By: Diane

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