Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Symposium marks 30th anniversary of discovery of third domain of life

17.10.2007
Thirty years ago this month, researchers at the University of Illinois published a discovery that challenged basic assumptions about the broadest classifications of life. Their discovery – which was based on an analysis of ribosomal RNA, an ancient molecule essential to the replication of all cells – opened up a new field of study, and established a first draft of the evolutionary “tree of life.”

To mark the anniversary of this discovery, the university is holding a symposium Nov. 3-4 (Saturday-Sunday), with a public lecture at the Spurlock Museum on the evening of Nov. 2. “Hidden Before Our Eyes: 30 Years of Molecular Phylogeny, Archaea and Evolution” will detail the exacting work that led to the discovery of a “third domain” of life, the microbes now known as the archaea. The event will revisit the program of research that led to the discovery, explore its impact on the study of evolution, and describe the way in which genetic analysis continues to revolutionize biology, in particular microbial ecology.

In 1977, microbiology professor Carl Woese led the team that identified the archaea as a unique domain of life, distinct from bacteria and other organisms. Prior to this finding, generations of evolutionary biologists and microbiologists believed that the microbes now called archaea were simply another taxon among bacteria. They had divided all living organisms into two broad superkingdoms, or domains: the “prokaryotes,” which included both the true bacteria and archaea; and “eukaryotes,” including all animals, plants, fungi and protists (a diverse group that includes protozoans, algae, slime molds and other organisms). Some prominent biologists still hold to this classification scheme.

Woese had set out to map the evolutionary history of life by comparing RNA sequences of a molecular sequence common to all living cells: the ribosome, which manufactures a cell’s proteins.

Each group of organisms contains sets of genetic sequences in their ribosomal RNA that are distinctive. These genetic “signatures” differentiate the groups. Woese’s analysis of a variety of organisms’ genetic signatures told a story that was different from the conventional wisdom, however.

This surprising discovery came when the researchers looked at the ribosomal RNA (rRNA) of a group of methane-generating microbes that had been classified as bacteria. Illinois microbiology professor Ralph Wolfe, an expert on these “methanogens,” was a member of Woese’s team, along with postdoctoral researcher George Fox, graduate student William Balch and lab technician Linda Magrum.

“Of all the numerous suggestions we had gotten for organisms to study, the one I solicited from my colleague, Ralph Wolfe, turned out to be the most important,” Woese wrote in an account of the discovery. “Ralph was in the process of working out the biochemistry of methanogenesis, which made it natural for him to suggest we characterize the methanogens.”

Wolfe was one of only a handful of researchers studying methanogens in the mid-1970s. These organisms were notoriously difficult to grow in culture because they could survive only in an oxygen-free atmosphere that was rich in hydrogen and carbon dioxide. Balch, a graduate student in Wolfe’s lab, had found a way to create a sealed and pressurized atmosphere inside a test tube that would support these organisms, however. Using this technique, a methanogen now called M. bryantii, was grown in sufficient quantities for study.

Woese had already found a collection of rRNA sequences that were specific to bacteria, and another set of sequences unique to plants, animals and other eukarya. When he sequenced the ribosomal RNA of Wolfe’s methanogen, however, he found that it was strikingly different from that of eukarya and bacteria. Although it shared some universal sequences with the other organisms, it also carried its own unique set of sequences that did not fit with either group. It was “neither fish nor fowl,” Woese said.

The scientists were astonished, and quickly turned their attention to other methanogens. The genetic pattern held: The rRNA signatures of the methanogens were distinct from those of eukaryotes and bacteria. Woese concluded that the methanogens were not bacteria.

Wolfe recalled, “When Carl said they weren’t bacteria, I said: ‘Of course they are bacteria! They look like bacteria! They have this prokaryotic morphology and cell structure.’ ”

But when Wolfe saw how the sequence data fell into discrete groups, with all the methanogens in a category of their own, “I became a believer,” he said.

Their findings were published in the Proceedings of the National Academy of Sciences in October 1977. The paper’s three-sentence abstract stated simply that “the methanogens constitute a distinct phylogenetic group… only distantly related to bacteria.”

A second PNAS paper, published the following month by Woese and Fox, outlined the evidence that there were three – rather than two – superkingdoms, or domains, of life.

“There was general amazement and feeling that something great had been discovered among the physical scientists,” Woese said.

Many microbiologists and other life scientists were unwilling to accept the new classification scheme, however. They continued to see the archaea as a highly differentiated offshoot of the bacterial line.

In 2003, Woese won the $500,000 Crafoord Prize in Biosciences for his discovery of this “third domain of life.” The prize, given by the Royal Swedish Academy of Sciences, marks accomplishments in scientific fields not covered by the Nobel Prizes in sciences, which the academy also selects.

Controversy over the work continued, however. Some scientists described the 1977 announcement of a third domain as an achievement comparable to that of the discovery of a new continent. Others discounted the idea as a “fantastic” hypothesis based on a limited and unreliable pool of data. To this day, many textbooks, dictionaries and other science reference materials include the “classical” and the Woese classification schemes.

Now 79, Woese continues his work as a member of the “Biocomplexity” theme at the Institute for Genomic Biology. He works with collaborators in physics, chemistry, geology and microbiology in a continuing exploration of the genomic complexity of biological systems. He worries about what he sees as a general lack of interest in evolution among microbiologists and other life scientists. And he hopes that a new generation of scientists will make full use of the genomic tools that he believes could revolutionize the study of the origins and evolution of life.

Wolfe, 86, an emeritus professor of microbiology, continues his interest in the physiology and biochemistry of the methanoarchaea.

More information about “Hidden Before Our Eyes,” is available at the symposium Web site: http://archaea.igb.uiuc.edu.

Diana Yates | University of Illinois
Further information:
http://www.news.uiuc.edu/news/07/1016thirddomain.html
http://archaea.igb.uiuc.edu

Further reports about: Archaea Discovery Domain Organisms RNA Woese methanogen microbiology ribosomal sequence

More articles from Life Sciences:

nachricht Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg

nachricht Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>