Understanding Biotechnology

What is Biotechnology

Overview of Biotechnology

History of Biotechnology

Why do we do biotechnology?

Biotechnology for the environment

Biotechnology for food and agriculture

A famous clone is Dolly the sheep, the very first cloned mammal, who was born in 1997.

Genes, plants and animals can all be cloned. The techniques behind cloning are discussed in the chapter called What is Biotechnology?.

Here, we look at what has been done with clones and why?

Cloning genes

Polymerase chain reaction (PCR) is used to make many copies of the gene of interest. The fragments of DNA can be analysed for forensic purposes, medical research and genetic studies.

Cloning animals

Dolly was produced by somatic cell nuclear transfer (SCNT). The nucleus of an egg cell from an adult sheep was removed and replaced with the nucleus from a mammary (udder) cell of an other adult sheep. The egg was then inserted into the uterus of a different sheep, where it developed into a sheep embryo just like a normal fertillised egg.

Dolly was an exact genetic copy (a clone) of the animal from which the mammary cell nucleus was taken — her genetic mother. But, although Dolly was genetically identical to her ‘mother', she was not her identical twin. Identical twins are genetically identical because they developed from the same fertilised egg, whereas Dolly's DNA came from a mature cell of her ‘mother'.

Dolly was put down at the age of six after developing a chronic lung disease. Her breed of sheep normally lives for ten to twelve years. An extensive post-mortem found no evidence to suggest that being a clone contributed to her early death.

Click on the image below to see how Dolly was cloned.

Since Dolly, many other mammalian species have been cloned, including cows, pigs, mice, cats, dogs and rats.

Monkeys have also been cloned; Tetra, a rhesus monkey, was the first primate to be cloned using a method that splits the original cells in an embryo to make multiple identical animals. However, the cloning process is still inefficient: only around 3% of cell nuclei that are transferred to donor eggs result in live births.

The Roslin Institute in Edinburgh produced Dolly the sheep: http://www.roslin.ac.uk/

Calf clone with a difference

Milk is recognised as a major source of nutrition, particularly of calcium and protein. The researchers, from Monash University and Genetics Australia Cooperative Limited, supported by the Cooperative Research Centre (CRC) for Innovative Dairy Products, wanted to investigate methods to efficiently increase milk's nutritional value.

The scientists added a cow milk protein gene to skin cells collected from an elite Holstein cow. The genetically modified cells were cultured and used to create embryos that were transferred into surrogate cows.

In 2002, fourteen GM calves were born that had the extra milk protein gene. They were Australia's first cloned calves. The Dairy CRC no longer does GM cow research, but scientists in New Zealand have produced GM cows that produce high-protein milk for the cheese industry.

High-protein milk is one of only many potential uses for GM cows. In the United States, for example, human medicines are already being produced in the milk of cows and goats. The technology could also be used to produce healthier animals with improved resistance to diseases.

Cooperative Research Centre for Innovative Dairy Products: www.dairycrc.com

Cloning humans?

But, why would we want a cloned human embryo?

The cloned embryo could either be:

• implanted into a uterus to grow into a whole organism (called reproductive cloning)
• harvested for embryonic stem cells that are used to grow into any type of tissue, (called nuclear transfer technology and previously known as therapeutic cloning).

All forms of human cloning are illegal in Australia.

Nuclear transfer - cloning human cells for therapy

Nuclear transfer does not result in pregnancy or the birth of a cloned baby. Instead, embryonic stem cells are removed at a very early stage and grown in the laboratory, until there are enough to be stimulated to develop into other human cell types like skin or muscle cells. This is the basis of stem cell research.

Stem cells could be used in many applications, including production of healthy cells to replace damaged cells in the body, or growth of organs for organ transplants.

Although nuclear transfer holds great potential as a mechanism to treat and cure diseases, it is also very controversial. This is because the embryo is destroyed when the stem cells are removed.

For this reason, research is currently focused on collecting stem cells from other sources, such as cord blood and adult tissues. These sources do not require the production of a cloned human embryo, and are therefore less controversial.

In Australia, nuclear transfer is illegal, because it is a form of cloning a human embryo.

Reproductive cloning - cloning a whole human

The aim of reproductive cloning is to produce a living clone of a human from their DNA. This technology is illegal in many countries around the world. The technique is not well established, and a number of ethical issues need to be discussed first.

The Australian Government, in agreement with most other countries, is opposed to the cloning of human beings for reproductive purposes, and has passed the Prohibition of Human Cloning Act 2002 (Cth).

The success rate of animal reproductive cloning is still very low, Many attempts are needed before a cloned embryo is formed, each time using hundreds of donor and egg cells. Cloned animals have presented a number of abnormalities in both their genes and development.

At present, the scientific community in general considers human cloning to be unethical, because of the safety and social concerns.

The possible uses of reproductive cloning could be to:

• reproduce endangered wildlife
• produce children for people who are unable to have a child
• clone a child that may have passed away.