Cloning Techniques


There are many different techniques used for cloning today.
The three major and main techniques used today are:
the Roslin Technique,
the Honolulu technique,
and "Twinning", the initial splitting of a zygote

For the Roslin Technique a sheep was used to experiment the technique on. The Roslin Technique has an adult donor cell and a unfertilized egg cell to start with. First the nucleus of an egg cell is removed. The nucleus is the structure that contains all the genetic information of the egg cell. Then donor cell is starved by lacking nutrients, this causes it to be in a suspended state. The reason for it is so that it will be a match with the enucleated egg cell. Then the donor and egg cell are placed closely together and with an electric pulse they are fused together to help development. Then the developing egg is placed into the oviduct of the sheep also known as the fallopian tube. It? purpose is to serve as an incubator as it takes the form of an embryo and further helps growth. After about six days in the oviduct of the sheep the embryo is placed into the uterus of a surrogate mother. A surrogate mother is the subject being used to carry and give birth to embryo that are not her own. Finally after a normal pregnancy, the surrogate mother will have a clone which contains the same genetic information of the adult donor cell.





For the Honolulu Technique mice were the subjects used to test the experiment. For a long time mice have been the most difficult animals to clone. This technique also has a lot of similarity to the Roslin Technique. For this technique we also have a donor cell and a unfertilized egg to start with. Cumulus cells are used because they remain natural in a suspended state then it is inserted into the enucleated egg. It takes about one full hour for the egg to adapt to it? new nucleus. After it is allowed to sit still for about five hours, yet no changes of development happen during that moment. After an additional five hours it is placed into a culture which helps with the development. The culture aids with development process as the electric pulse does with the Roslin Technique but less stress is put on the cell. Later the egg cell develops into an embryo which is then placed into the uterus of a surrogate mother mouse. After a normal term of pregnancy for a mouse a clone is born. It is also believed that the Honolulu technique is the most effective technique up to date.



For the twinning technique, a monkey was used for the experiment. First a sperm sample and an egg from a mother are gathered for the technique. After fertilization of the egg, it grows into eight different cells, researchers then split them up into four different embryos where each have two cells. Last, the four embryos are implanted into surrogate mothers, unfortunately three of the embryo did not survive, but the fourth did and a cloned monkey was born called Tetra.





SOURCES
http://www.stedwards.edu/newc/capstone/sp2000/biotechnology/ways.htm

http://library.thinkquest.org/24355/data/createnav.html?tqskip1=1&tqtime=1201

http://www.cnn.com/2000/NATURE/01/13/monkey.cloning/