Biotechnology (continued)
Gene functions can often be blocked by attacking them with
complementary or antisense sequences of the same gene. This
technology has been used by molecular biologists to define
functions for specific genes, but it has also been shown to have
a number of practical applications. In agriculture, it has been
used to generate male sterile plants, enabling the production
of hybrid varieties more easily, and to slow the ripening of
tomatoes. Most importantly, antisense technology presents
the possibility of useful gene therapy. For example, the human
immunodeficiency virus (HIV, the causal agent of AIDS) can be
inhibited by transforming T lymphocytes with antisense nucleic
acids directed against a virus enzyme, reverse transcriptase.
It is now possible to put foreign genes into cells and target
them to specific regions of the recipient genome. This presents
the possibility of developing specific therapies for hereditary
diseases, exemplified by sickle cell anemia, which is caused by
a defect in the β-globin gene that results in defective hemoglo-
bin in affected individuals.
Environment
Microorganisms, either genetically engineered or selected
from natural populations, are used to degrade toxic wastes in
the environment. For example, polycyclic aromatic compounds,
including polychlorinated biphenyls, and petroleum prod-
ucts that contaminate soil and groundwater supplies may be
degraded by populations of microorganisms. These technolo-
gies have the potential to solve some significant environmental
problems. Waste products of industry and agriculture are being
composted, with added microorganisms selected for their
capacity to degrade organic materials.
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