Kuang Dong Wuu
The elucidation of DNA double helical structure in 1953 by Watson and Crick opened
up the revolutionary era of molecular biology. A tremendous progress has been made
in the field of biological sciences in the past 50 years. At the same time, somatic cell
culture, in vitro fertilization, nuclear transplantation, and the establishment of
embryonic stem cell lines are all flourished during this period This lecture will outline
the most important breakthroughs in biotechnology at both molecular and cellular
levels and their possible mpacts on future human well-being.
Four key molecular technologies
1.Recombinant DNA
After the discovery of restriction endonuclease by H.Smith and D.Nathans in
1970,scientists are able to transfer a gene or a fragment of DNA from one species
to another,e.g.,a human insulin gene to a bacterial plasmid .this is called genetic
engineering and a powerful tool in biotechnology.
2.Amplification of recombinant DNA molecules in cloning vectors
The gene or DNA sequence of interest is inserted into a specially chosen cloning
vector.Most of the commonly used cloning vectors have been derived from viral
chromosomes or plasmids.
3.Amplification of DNAS by the polymerase chain reaction
The polymerase chain reaction ,usually referred to as PCR,is an extremely
powerful procedure that allows the amplification of a selected sequence in a
genome a millionfold or more .PCR can be used to clone a given DNA sequence in
vitro ,without the use of living cells during the cloning process.
4.Transgenic plant and animals
Transgenic animals :By microinjection of DNA into fertilized eggs.
Transgenic plants :By using the Ti plasmid of Agrobacterium tumefaciens as
Application of genetic engineering
1.Genomic studies of various organisms
Genomic is the subdivision of genetics devoted to the mapping ,sequencing and
Functional analysis of genomes. The genomics was divided into structural
genomics---the study of genome structure---and functional genomics---the study of
genome function . New array hybridization and gene chip technologies allow
researchers to monitor the expression of entire genomes---all the genes in an
organism---at varies stages of growth and development or in response to
environmental changes.
2.Diagnosis,prevention and therapy of human inherited diseases
The mutant genes responsible for several inherited human diseases can be
Accurately diagnosed by screening genomic DNA for the genetic defect . The
Results of these tests provide information that allow genetic counselors to inform
Families of the risk of an affected child .
Gene therapy involves the addition of a normal copy of a gene to the genome of an
Individual who carries defective copies of the gene . Physicians are currently testing
The effectiveness of somatic gene therapy in the treatment of patients with
Adenosine deaminase-deficient severe combined immunodeficiency disease.
3.Paternity test and forensic application
DNA fingerprints detect and record polymorphisms in the genomes of individuals .
DNA prints provide strong evidence of individual identity ,evidence that may be
Extremely valuable in paternity and forensic cases .
4.Production of eukaryotic proteins in bacteria
Valuable proteins that could be isolated from eukaryotes in small amounts and at
Great expanse can now be produced in large quantities in genetically engineered
Bacteria . Proteins such as human insulin and human growth hormone are valuable
Pharmaceuticals used to treat diabetes and pituitary dwarfism,respectively . Other
Proteins have important industrial applications .
5.Gene vaccine
Genes that produce viral proteins or bacterial proteins can be inserted into plasmid
DNA . By subcutaneous injection of the recombinant plasmid into human body ,the
Viral or bacterial genes are expressed which can induce the human immune
6.The applications of transgenic plants
Synthetic, modified or other foreign genes can now be introduced into most plants.
The resulting transgenic plants provide valuable systems in which to study
the function of the individual genes. Many transgenic crops, such as soybean,
cotton,wheat, etc., are extremely important their commercial value.
7.The applications of transgenic animals
Transgenic mice are produced routinely in laboratories throughout the world. They
provide valuable tools for the study of gene expression in mammals and an excellent
model system with which to test various gene-transfer vectors and methodologies
for possible use in humans.
Another potentially important use of transgenic animals is for the production and
secretion of valuable proteins in milk.
Applications of cell culture and nuclear transplantation
Cell culture
Every cultured human cell contains the whole human genome. We can study the
gene defects and metabolic errors by studying the cultured cells.
In vitro fertilization
By fusing human perms and eggs in vitro and then transfer the early embryos into
female, a perfect normal baby can be born in this way . It is so called test tube baby.
This has been in common practice for over two decades all over the world.
Nuclear transplantation
Transfer of a single nucleus at a specific stage of development, to an enucleated
unfertilized egg, provided an opportunity to investigate whether cellular
differentiation to that stage involved irreversible genetic modifications. Nuclear
transplantation from adult somatic cells have been successfully used to produce
sheep, cattle, mouse, and other mammals.
Establishment of human embryonic stem cell lines
Human blastocyst-derived cell lines have been established that have normal
karyotypes, express high level of telomerase activity, and express cell surface
markers that characterize primate embryonic stem cells but do not characterize
other early lineages. These cell lines should be useful in human developmental
biology, drug discovery, and transplantation medicine.
The relevance of biotechnology to many aspects of human life and society,
including health insurance; food production; forensics; ethics of human reproduction;
prevention, treatment, and gene therapy of human inherited diseases, in chronicled
almost daily in the news media. Both positive and negative impacts on human life will
be prevailing in the future.