What Is Biotechnology? - Biotechnology and Your Health: Pharmaceutical Applications - page 20

CONNECTIONS
The ability to move a gene from one organism to another at will was
built on basic discoveries about the biology and genetics of cells and
whole organisms. The biotechnologist's toolbox includes methods
to precisely clip DNA and insert it into a new cell, along with other
Reproductive Cloning
Laboratory methods have been used to produce animals that are genetically identical to
one another. These procedures are also called cloning, specifically reproductive cloning,
because the goal is to produce a live animal. Animal and human clones are not unknown.
Identical twins, because they derive from the same fertilized egg that splits into two, are
genetically identical, and each is therefore a clone of the other. But the form of cloning
that concerns and sometimes alarms people is the process by which the nucleus of an
adult individual's cell is substituted for the nucleus of a fertilized egg, with the goal of
generating a genetic copy of the donor of the nucleus. Dolly the sheep, the first cloned
mammal, was produced in 1996 by substituting the nucleus from a skin cell of a sheep
for the nucleus of an unfertilized egg. Many such transfers were done, and each egg was
cultured in the laboratory until it developed into an embryo and was then placed into the
uterus of an ewe treated with hormones to mimic pregnancy. Hundreds of embryos were
produced, but only one resulted in a live birth. Others died early in development or were
born with fatal birth defects. A similar method has been used to produce cloned sheep,
goats, cows, mice, pigs, cats, rabbits, and a gaur, which is an endangered ox. The method
is called somatic nuclear transfer ( SNT ). The cells in animal and human bodies
destined to develop into sperm or eggs are called germ cells , and the rest of the cells
are called somatic cells . The process is not a sure thing. In every species in which SNT
has been tried, experience has shown that many embryos die early in development or,
if born alive, have significant birth defects.
The morality and ethics of human reproductive cloning have been hotly debated
since Dolly's birth, and the issues are of great concern to many religious faiths. The debate
centers on respect for the earliest form of human life, and different ideas about the stage
of development at which a human embryo should be granted protection as a “person.”
This debate will not be easily cooled. Ethical and moral issues aside, after thorough review
of results with different animal species, the scientific and medical consensus is that
reproductive cloning of humans is too dangerous and should not be attempted.