What is Cloning?
"Cloning"
– an umbrella term traditionally used by scientists to describe different processes for duplicating biological material. Generally speaking, cloning refers to
copying genes and other pieces of chromosomes to generate enough identical material – DNA – for further study. Two other types of cloning
produce complete, genetically identical animals: - Blastomere separation
(sometimes called "twinning" after the naturally occurring process that creates identical twins) involves splitting a developing embryo soon after fertilisation of the egg by a sperm (sexual reproduction) to give rise to two or more embryos.
The resulting organisms are identical twins (clones) containing DNA from both the mother and the father. Using somatic cell nuclear transfer, scientists transfer genetic material from the nucleus of an adult cell to an egg whose nucleus, and thus its genetic material, had been removed. (All cells that are not egg or sperm cells are somatic cells.) This is how Dolly was produced – transferring the nucleus of an adult sheep's udder cell to an emptied egg cell.
Why clone?
One goal of research on cloning is to develop efficient ways to alter animals genetically and reproduce them reliably.
Alterations have included adding genes (such as those for human proteins) to
create drug-producing animals or directly add a normal gene to an individual with a particular disease-causing defect (gene therapy). Others have tried
to
inactivate genes to study the effects and possibly create animal models of human diseases. Cloning technology may also someday be used in therapy for humans:
- to produce whole organs
from single cells, or - to
strengthen a diseased organ by injection of a few healthy cells, or - to
raise animals having genetically altered organs that are suitable for transplanting into humans (xenotransplantation).
The technique used to produce Dolly and other cloned animals is an extension of 40 years of research using DNA from non-human embryonic and fetal cells.
Before this demonstration, scientists believed that once a cell transformed to a specialised liver, heart, udder, bone, or any other type of cell, the change was permanent and unneeded genes in the cell became permanently inactive.
Dolly's creators demonstrated that nuclei of an adult animal’s specialised cells can be made to revert to a non-specialised, embryonic state, thus restoring the ability to give rise to any kind of cell.
Explorations into how cells revert to an undifferentiated state may also provide insights into the process by which cells become cancerous.
Using the same technique that produced Dolly, researchers have cloned a number of large and small animals including sheep, goats, mice and cows. But scientists still remain uncertain about whether genetic changes in the cells used to obtain nuclei will lead to adverse effects on the health of the cloned animals.
More on cloning:
Cloning Fact Sheet - Human
Genome Project Information.
From The
Human Genome Program of the U.S. Department of Energy. Human Genome Project Information Website Roslin Institute – Where Dolly was produced. Cloning issues in reproduction, science and medicine
A consultation paper prepared in January 1998 by the Human Genetics Advisory Commission as part of a joint UK wide exercise with the Human Fertilisation and Embryology Authority, with a particular emphasis on implications for human medicine (January 1998).
The final report, also entitled Cloning issues in reproduction, science and medicine was issued in December 1998. Prohibition of Cloning Human Beings Council of Europe
Includes the text and background notes to the Protocol banning human cloning in Europe (January 1998), developed under the Convention on Bioethics.
Council of Europe and Bioethics
Nuffield Council on Bioethics
An advisory body sponsored by the Nuffield Foundation to examine ethical issues arising from recent advances in biological and medical research. Welcome to the DEFRA website – Department for Environment, Food & Rural Affairs, UK. Geron Corporation
Company focused on developing therapeutic and diagnostic products for regenerative medicine – like telomerase, human embryonic stem cells and nuclear transfer. PPL Therapeutics plc
One of the world's leading companies in the application of transgenic technology to the production of human proteins for therapeutic and nutritional use. Ifgene
International Forum for Genetic Engineering. An international forum to promote discussion about the moral and ethical aspects of genetic engineering, includes a list of further sources. (US) Biotechnology Information Center
A useful starting point for information on all aspects of biotechnology provided by the (US) National Agricultural Library (US) National Biotechnology Advisory Committee
NIH Web site for the body advising the US government on biotechnology issues (US) National Bioethics Advisory Commission
An advisory body set up by President Clinton in 1995 to deal with the implications of recent advances in biological and medical research. See Reports for their report on human cloning (June 1997). (US) National Reference Center for Bioethics Literature
A US national resource for literature and resources relating bioethics. Reflections on cloning
Vatican’s view on cloning
and
notes on cloning (September 1997). 
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