 |
|
Symposium marks 30th anniversary of discovery of third domain of life
October 17, 2007CHAMPAIGN, Ill. - 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.
University of Illinois at Urbana-Champaign
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.
University of Illinois at Urbana-Champaign
Archaea Current Events and Archaea News RSSUnusual microbial ropes grow slowly in cave lake
Deep inside the Frasassi cave system in Italy and more than 1,600 feet below the Earth's surface, divers found filamentous ropes of microbes growing in the cold water, according to a team of Penn State researchers.
New cell division mechanism discovered
A novel cell division mechanism has been discovered in a microorganism that thrives in hot acid. The finding may also result in insights into key processes in human cells, and in a better understanding of the main evolutionary lineages of life on Earth.
Bold traveler's journey toward the center of the Earth
The first ecosystem ever found having only a single biological species has been discovered 2.8 kilometers (1.74 miles) beneath the surface of the earth in the Mponeng gold mine near Johannesburg, South Africa.
The Structure of the Mre11 Protein Bound to DNA
Repairing breaks in the two strands of the DNA double helix is critical for avoiding cancer. In humans and other organisms, a molecular machine called the MRN complex is responsible for finding and signaling double-strand breaks (DSBs), then launching the error-free method of DNA repair called homologous recombination.
Molecular sleuths track evolution through the ribosome
A new study of the ribosome, the cell's protein-building machinery, sheds light on the oldest branches of the evolutionary tree of life and suggests that differences in ribosomal structure between the three main branches of that tree are "molecular fossils" of the early evolution of protein synthesis.
Study reveals surprising details of the evolution of protein translation
A new study of transfer RNA, a molecule that delivers amino acids to the protein-building machinery of the cell, challenges long-held ideas about the evolutionary history of protein synthesis.
Microbes beneath sea floor genetically distinct
Tiny microbes beneath the sea floor, distinct from life on the Earth's surface, may account for one-tenth of the Earth's living biomass, according to an interdisciplinary team of researchers, but many of these minute creatures are living on a geologic timescale.
Nature publishes new evidence about the deep biosphere written by biogeoscientists
Biogeoscientists show evidence of 90 billion tons of microbial organisms-expressed in terms of carbon mass-living in the deep biosphere, in a research article published online by Nature, July 20, 2008.
Deep sea methane scavengers captured
Scientists of the Helmholtz Centre for Environmental Research (UFZ) in Leipzig and the California Institute of Technology (Caltech) in Pasadena succeeded in capturing syntrophic (means "feeding together") microorganisms that are known to dramatically reduce the oceanic emission of methane into the atmosphere.
Manufactured Buckyballs don't harm microbes that clean the environment
Even large amounts of manufactured nanoparticles, also known as Buckyballs, don't faze microscopic organisms that are charged with cleaning up the environment, according to Purdue University researchers.
More Archaea Current Events and Archaea News Articles
 | Bergey's Manual of Systematic Bacteriology Volume 1: The Archaea and the Deeply Branching and Phototrophic Bacteria by George M. Garrity Michigan State Univ., East Lansing. Major provider of an outline of bacterial systematics since 1923. For microbiologists at all levels and in all sub-disciplines. Previous edition: c1984. Complete in four... |
 | Archaea: Molecular and Cellular Biology |
 | Archaea: Evolution, Physiology, and Molecular Biology Introduced by Crafoord Prize winner Carl Woese, this volume combines reviews of the major developments in archaeal research over the past 10-15 years with more specialized articles dealing with important recent breakthroughs. Drawing on major themes presented at the June 2005 meeting held in Munich to honor the archaea pioneers Wolfram Zillig and Karl O. Stetter, the book provides a thorough... |
 | The Surprising Archaea: Discovering Another Domain of Life by John L. Howland Although they comprise one of the three fundamental branches of life, the Archaea were only recognized as a group about twenty years ago. This recognition was based on similarities between their RNA sequences, similarities all the more striking because of the diversity of archaeal lifestyles. They include microorganisms that live in boiling water, within the guts of animals, or in concentration... |
 | Archaea: New Models for Prokaryotic Biology |
| The Third Domain: Untold Story of Archaea and the Future of Biotechnology.(Book review): An article from: The Humanist by Kenneth Krause This digital document is an article from The Humanist, published by American Humanist Association on March 1, 2008. The length of the article is 1446 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser.Citation DetailsTitle: The Third Domain: Untold Story... | |
 | Respiration in Archaea and Bacteria: Diversity of Prokaryotic Respiratory Systems (Advances in Photosynthesis and Respiration) The book summarizes the achievements of the past decade in the biochemistry, bioenergetics, structural and molecular biology of respiratory processes in selected genera of the domain Bacteria along with an extensive coverage of the redox chains of extremophiles belonging to the Archaean domain. The volume is a unique piece of work since it contains a series of chapters dealing with metabolic... |
 | Archaea: A Laboratory Manual The protocols in these three books are selected to provide a detailed guide to experiments with the methanogenic, extremely halophilic, and thermophilic sulfur-utilizing Archaea, with overviews to highlight areas of future development. The individual protocols consist of an introduction describing the specific applications of the techniques, step-by-step procedures for applying the protocols,... |
| Molecular Biology of Archaea: Based on the Symposium Molecular Biology of Archaea, May 11-14, 1993, Munich, Frg by Felicitas Pfeifer, Peter Palm | |
| Production, Purification and Charactization of Novel Thermoactive Glucoamylases from the Hyperacidophilic Archaea Thermoplasma Acidophilum, Picrophilus ... Oshimae (Berichte Aus Der Biotechnologie) by Ehab Serour |
| © 2009 BrightSurf.com |