Campus scientists complete genome
Hartman Cohen, News Office staff
team of University scientists led by Microbiology professor Shiladitya
DasSarma, in collaboration with noted molecular biotechnologist
Leroy Hood of the Institute of Systems Biology (ISB) in Seattle,
has completed the genome sequence of Halobacterium species NRC-1,
an "extremophilic" microorganism that grows best in an
environment 10 times saltier than sea water. The achievement was
published in the Oct. 3 edition of the journal Proceedings of the
National Academy of Sciences (PNAS).
This not only
is the first genome project completed on campus, according to University
researchers, but the first genome of any halophile (salt-loving
microbe) and one of the first of several dozen genome projects of
whole organisms ever completed, according to The Institute for Genomic
on Halobacterium should contribute toward some of the greatest unsolved
mysteries of biology today, including our understanding of evolution
as well as of the fundamental life process in higher cells,"
says DasSarma. "There is a tremendous genetic resource in the
genomes of microorganisms. In fact, it is one of the last, largely
untapped, natural resources on our planet."
DasSarma and Hood
led a consortium of researchers from 12 universities and research
centers in the U.S., Canada, and the U.K., on the three-year, $1.2-million
project funded by the National Science Foundation (NSF). Participating
institutions included Stanford University, University of Wisconsin,
University of Pennsylvania, and the Marine Biological Laboratory
at Woods Hole, Mass.
NRC-1 is a member of the archaea, the third branch of life in the
biological world. Archaea are evolutionary relics, microorganisms
that are among the most ancient forms of life, yet they represent
a third of all living creatures. Astronomical numbers of Halobacterium
-- which are microscopic, rod-shaped organisms -- can be found in
bodies of very salty water, including the Great Salt Lake and the
Dead Sea. The single-celled organism utilizes sunlight to synthesize
energy, giving off a red byproduct, and has been harvested for commercial
use for its light-sensitive properties. When a body of water turns
bright pink or red, it is often a sign that millions of halo-bacteria
are present. These microorganisms, and their red pigment, can remain
in salt crystals left behind long after a lake dries up.
genome is one of the first and only genetically tractable archaea
to be sequenced. As such, it represents the key to both unlocking
the scientific mysteries of archaea and opening avenues of practical
use of our natural genetic resources," says DasSarma. According
to DasSarma, this particular genome will serve as an excellent model
for all organisms in the archaeon. "Some aspects of the biology
of Halobacterium resemble higher cells called eukaryotes, especially
the means by which cells turn genes on or off. An understanding
of this genome will help us learn how cells regulate genes. We have
not observed such a sophisticated regulatory network in such a primitive
that a handful of organisms in the archaea have been sequenced before,
but this is the first halophile, or salt-loving organism. Because
they can live under extreme conditions, Halobacterium are easy to
culture. And, because they are completely harmless to humans, the
study of this genome can be useful for teaching biological principles
in colleges and schools, according to the microbiologist.
"These tiny creatures will provide many insights into how more
complex creatures manage life functions, including cell division,
and the way cells transport proteins across biological membranes.
Right now, several biomedical applications using Halobacterium are
being investigated, including the development of orally administered
vaccines, and the design of new antibiotics."
NSF program director
Joanne Tornow says the foundation's goal is to catalyze the development
of similar genomic research. "Genomic projects have produced
a great deal of data, but we're just getting to the point where
we can find answers to a lot of the most interesting biology questions,"
she said. "Every day, we learn more about functional, comparative
and structural genomics. This data will allow us to ask questions
we couldn't ask before."
Leroy Hood may
be best known as the creator of DNA sequencing technology. Forty-three
researchers, including the team leaders, participated in producing
the manuscript outlining their findings.
Ng, who earned his Ph.D. here in 1993 and is currently on the faculty
of ISB, was first author of the manuscript.