Biologist Battles Conventional Wisdom for Thirty Years

Are there really three forms of life on the earth? For years, scientists have classified organisms into one of two superkingdoms, prokaryote and eukaryote. For thirty years, a group of scientists from the University of Illinois have said there are three, fighting up an uphill battle against conventional wisdom which is akin to Gallileo telling the Church that the earth was round.

What distinguishes a prokaryote from a eukaryote is the cell structure and organization. Prokaryotes have no nucleus, they are basically a bag filled with structured organic chemicals. Eukaryotes, on the other hand, have a distinct nucleus as well as a variety of other organ-like structures (organelles) in which discrete functions are carried out.

In 1977, a team of researchers under the leadership of Microbiologist Carl Woese were working with methanobacters, attempting for to be the first group to effectively grow cultures to determine how this strain of bacteria makes methane. The researchers created a means of sealing and voiding test tubes, then refilling them in an atmosphere somewhat akin to that which existed about 3.5 billion years ago in the Archaaen Era, when there was no free oxygen in the air. Methanobacters will not reproduce in an oxygen-rich environment, and require large amounts of hydrogen and carbon dioxide.

This gave the scientists an abundance of this bacteria for the first time, enough to study their entire structure, including the RNA in their ribosome-like structures. Ribosomes in eukaryotes are organelles which help in the transcription of DNA into proteins as well as 'oversee' the actual production of certain materials.

The scientists' surprise, the RNA in the methanobacters did not "match up" with the RNA from other types of bacteria, to a similar extent as the RNA from prokaryotes differs from that in eukaryotes. The researchers then set about the task of testing and comparing a variety of bacteria, and discovered that certain families shared the same characteristics with the newly-named archae organisms, and had the same level of differentiation from more advanced bacteria.

The team quickly published their findings in the Proceedings of the National Academy of Sciences in October 1977 with a simple three sentence abstract that belied the revolutionary nature of their findings. They followed up that paper the following month with their detailed data in the same journal, which was met with general approval and amazement by some, and ridicule and disbelief by others.

Some evolutionary biologists have embraced the theory, which neatly fills in a gap in their own studies on the increased complexity of the eukaryotes over prokaryotes. Some have postulated that the archae were at some time engulfed and incorporated into the structures of more advanced organisms, eventually leading to the organelles present in virtually every plant and animal today.

The University of Illinois will be presenting a symposium on the subject entitled "Hidden Before Our Eyes: 30 Years of Molecular Phylogeny, Archaea and Evolution" on November 2, 2007 at 7 p.m. at the Spurlock Auditorium on the Urbana-Champaign campus.