Chapel Hill, NC (12/10/99)- The discovery of the minimum numbers of
genes required to produce a living organism will make it possible for scientists
to create new life forms from scratch, a prospect likely to spur considerable
ethical debate.
Researcher
Dr. Clyde A. Hutchison III, professor of microbiology at the University of
North Carolina, and colleagues began with Mycoplasma genitalium, the smallest
known genome capable of independent replication, with 517 genes. Using a a
process of elimination strategy called global transposon mutagenesis, the
researchers disrupted the genes one at a time to determine which were essential
for survival. This revealed that 255 to 340 of protein-coding genes were essential
to life.
"Cells that grow and divide after this procedure can have such disruptive
insertions only in nonessential genes. Surprisingly, the minimal set of genes
we found included about 100 whose function we don't yet understand. This finding
calls into question the prevailing assumption that the basic molecular mechanisms
underlying cellular life are understood, at least broadly," said Dr. Hutchison.
Image- Genome
Map of M. genitalium (click
to enlarge)
Credit:
Owen White, TIGR
While the researchers took a giant step towards creating life, they did not
produce any new life forms. Defining the minimal set of genes required for
an organism to survive in the lab is the first step. There are more elements
to basic life. It is also essential to know what other cellular components
such as proteins and sugars are needed for metabolism and replication. Another
major challenge will be learning how to assemble all of these elements along
with DNA.
The ability to create organisms from new and existing genomes would further
accelerate the rapid rate of development of genetic engineering and biotechnology.
Research in this area could also contribute to the basic understanding of
how life originated and evolved on the planet.
"The prospect of constructing minimal and new genomes does not violate any
fundamental moral precepts or boundaries, but does raise questions that are
essential to consider before the technology advances further. How does work
on minimal genomes and the creation of new free-living organisms change how
we frame ideas of life and our relationship to it? How can the technology
be used for the benefit of all, and what can be done in law and social policy
to ensure that outcome?" asked Dr. Mildred K. Cho of the Stanford University
Center for Biomedical Ethics in an essay in the journal Science.
"The temptation to demonize this fundamental research may be irresistible,"
she said. "However, the scientific community and the public can begin to understand
what is at stake if efforts are made now to identify the nature of the science
involved and to pinpoint key ethical, religious and metaphysical questions."
This new direction in biotechnology could accelerate the pace at which genetically
modified organisms are developed.with unknown and unpredictable effects on
the environment. Unraveling the genomes of harmful bacteria could lead to
new kinds of treatments for infectious disease. However, this knowledge could
also be used to create new infectious agents that could be d as biological
weapons. Ultimately, it might be possible to create modified forms of more
advanced life forms, up to and including humans.
For all of these and many other reasons, it is important that avenues of
communication and discussion among scientists, religious leaders, biomedical
ethicists and the public remain open regarding the various implications of
this new direction in biological research, Cho stressed.
The research appears appears in the Dec.10, 1999 issue of the journal Science.
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