Chimeric monkeys grown from zygotes
By Nicholai Cushing
Cloning has been the basis of many science fiction programs, books and films for many, many years, but cloning may be more possible than ever before. The Oxford Dictionary defines clone as “… an organism or cell, or group of organisms or cells, produced asexually from one ancestor or stock, to which they are genetically identical” (OxfordDictionaries 2012). Dolly the sheep was one of the most notable clones in history although she only lived from 1996 to 2003. Her untimely death still fuels much of the debate on cloning ethics happening today (Science Museum). Creating a stable and efficient cloning program may be a long way in the future but Masahito Tachibana of the Oregon National Primate Research Centre (Shepherd R.2012) has made a huge advance in embryonic stem cell research.
Rhesus Monkey: Image source ARKive <http://www.arkive.org/rhesus-macaque/macaca-mulatta/image-G13876.html>
Masahito Tachibana and his team have managed to successfully breed three chimeric male monkeys all now between four and six months old. The monkeys were grown directly from stem cells contained in early zygotes and incubated in females. The product was three male Rhesusmonkeys (Macaca mulatta) each with mixed DNA from six distinct lineages (Shepherd R. 2012). The monkeys essentially have up to six genetic parents caused by the mixture of DNA in the chimeric embryos but all have identical sets of DNA making them all clones of each other. When the stem cells were extracted from the embryos the research team used zygotes still in the very early developmental stages to extract totipotent stem cells. Usually the embryonic stem cells are grown in petri dishes in lines instead of being extracted from the early zygotes (Shepherd R.2012) and this suggests that these fresh stem cells have more potency then stem cells from frozen embryos. This could mean that due to monkeys and humans coming from a common ancestor in the primate family that cloning from human stem cells is not far off. There are huge debates about the use of human embryonic stem cells in research with scientific, religious and other groups clashing about meddling with these cells. Some adult tissues also contain stem cells but these are not totipotent and can only generate cells exactly the same or very closely related for example red and white blood cells (Medical NewsToday).
Stem cell formation (this diagram is for humans but applies to many other animals): Image source <http://en.wikipedia.org/wiki/File:Stem_cells_diagram.png>
This new research by Tachibana and his team may hold some of the solutions to being able to viable human organs, nerve fibres and tissues from totipotent stem cells but also opens the door to the possibilities of curing some diseases such as Parkinson’s (Shepherd R. 2012). The sooner the issues surrounding human stem cell research are resolved the sooner scientists can begin to pursue further testing and research in this very important genetic field. The birth of the three monkeys Chimero, Roku and Hex is a huge leap now but only a tiny step in the right direction.
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Science Museum, Dolly the sheep, 1996-2003, viewed 14 March 2012
Shepherd R. 2012, Monkeys Born From Stem Cells, press release, 07 January 2012, Medical News Today, viewed 12 March 2012