Somatic Cell Nuclear Transfer

From Embryology

Introduction

Page Under Development

Dolly the Sheep
Mice cloned from adult keratinocytes[1]

In 1996 Dolly the sheep was the first animal to be produced by somatic cell nuclear transfer (SCNT) using an adult-derived somatic cell as nuclear donor. A somatic cell refers to the fact that a cell that is not a germ cell (spermatozoa, oocyte) is used to generate a zygote from which the embryo develops. This topic is closely related to Stem Cells.

A range of different cell types has now been successfully applied to a range of species (cattle, mice, goats, pigs, cats, rabbits, horses, rats, dogs and ferrets. (see review[2])

SCNT Links: Introduction | Stem Cells - Induced | Stem Cells - SCNT | Epigenetics | Stem Cells | ART | Fertilization | Week 1 | Category:Zygote

Some Recent Findings

  • Inheritance of mitochondrial DNA in serially recloned pigs by somatic cell nuclear transfer (SCNT)[3] "Somatic cell nuclear transfer (SCNT) has been established for the transmission of specific nuclear DNA. However, the fate of donor mitochondrial DNA (mtDNA) remains unclear. Here, we examined the fate of donor mtDNA in recloned pigs through third generations. ... These results indicate that heteroplasmy that originate from donor and recipient mtDNA is maintained in recloned pigs, resulting from SCNT, unlike natural reproduction."
  • Number of blastomeres and distribution of microvilli in cloned mouse embryos during compaction[4] "We concluded that: (i) the cleavage of blastomeres in cloned embryos was slow at least before compaction; (ii) the distribution of microvilli in cloned, normal, parthenogenetic, and tetraploid embryos was coherent before and after compaction; and (iii) the initiation of compaction in somatic cell nuclear transfer (SCNT) embryos was delayed compared with that of intracytoplasmic sperm injection (ICSI) embryos."

SCNT Animal Timeline


Oocyte Enucleation

Sheep OOcyte Nucleus[10]

Before a somatic cell nuclei can be introduced into an oocyte, the oocyte's own nucleus needs to be removed. This process of oocyte nuclear removal is described as "oocyte enucleation". A recent study in cattle found oocyte imaging had a higher efficiency. [11]

The oocyte nucleus can be identified by:

  1. Hoechst staining and UV irradiation.
  2. Oocyte imaging.

Somatic Cell Source

A number of different tissues have been used as the somatic cell nucleus source including:

  • ovarian cumulus cells
  • fibroblasts
  • mammary epithelium
  • lymphocytes
  • neural stem cells
  • olfactory
  • myoblasts

Epigenetics

Several studies have reported that introduction of the somatic nuclei leads to deleterious epigenetic changes including DNA methylation and histone acetylation.

Mitochondria

Legislation

This technique essentially results in a clone of the original animal and therefore has been regulated by different countries in many different ways.

Australia

2010 - Cloning Legislative Review Committee Established

An independent committee has been established by the Federal Government to review cloning legislation in Australia (22 December 2010).

The independent Legislation Review Committee for the review of the Prohibition of Human Cloning for Reproduction Act 2002 and the Research Involving Human Embryos Act 2002 was announced today by the Federal Minister for Mental Health and Ageing, Mark Butler.

2006 - Prohibition of Human Cloning for Reproduction and the Regulation of Human Embryo Research Amendment Act 2006 (formerly known as the Patterson Bill) came into effect in June 2007.

2002 - Research Involving Human Embryos Act 2002 and the Prohibition of Human Cloning Act 2002 were passed by Parliament in December 2002.

Links: Cloning Legislative Review Committee Established | - Cloning | Australian Statistics

USA

2012 - Human somatic cell nuclear transfer and cloning by The Ethics Committee of the American Society for Reproductive Medicine.[12]

"This document presents arguments that conclude that it is unethical to use somatic cell nuclear transfer (SCNT) for infertility treatment due to concerns about safety; the unknown impact of SCNT on children, families, and society; and the availability of other ethically acceptable means of assisted reproduction. This document replaces the ASRM Ethics Committee report titled, "Human somatic cell nuclear transfer (cloning)," last published in Fertil Steril 2000;74:873-6."

References

  1. <pubmed>17299040</pubmed>| PMC1815251
  2. <pubmed>22681293</pubmed>
  3. <pubmed>22809505</pubmed>
  4. <pubmed>20735894</pubmed>
  5. <pubmed>8598906</pubmed>
  6. <pubmed>9596577</pubmed>
  7. <pubmed>9690471</pubmed>
  8. <pubmed>10331804</pubmed>
  9. <pubmed>10993078</pubmed>
  10. <pubmed>22132111</pubmed>| PLoS One.
  11. <pubmed>22816525</pubmed>
  12. <pubmed>22795681</pubmed>

Journals

  • Zygote An international journal dedicated to the rapid publication of original research in early embryology, Zygote covers interdisciplinary studies in animals and humans, from gametogenesis through fertilization to gastrulation.

Reviews

<pubmed>22536140</pubmed> <pubmed>22000472</pubmed> <pubmed>21982229</pubmed> <pubmed>21555407</pubmed> <pubmed></pubmed> <pubmed></pubmed> <pubmed></pubmed> <pubmed></pubmed>

Articles

Search Pubmed

August 2012 "somatic cell nuclear transfer" All (1883) Review (360) Free Full Text (585) Published in 2012 (125)

Search Pubmed: somatic cell nuclear transfer


Glossary Links

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Cite this page: Hill, M.A. (2024, March 28) Embryology Somatic Cell Nuclear Transfer. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Somatic_Cell_Nuclear_Transfer

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G