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Why is there life? U of I researchers and a multidisciplinary team seek the answer
By Susan Jongeneel
Media/Communications Specialist, University of Illinois College of Agricultural, Consumer and Environmental Sciences
URBANA, Ill. — University of Illinois microbiologists Isaac Cann and Roderick Mackie of the Animal Sciences Department at the College of Agricultural, Consumer and Environmental Sciences (ACES) said that an $8 million, five-year NASA Astrobiology Institute (NAI) grant just awarded to scientists working at the Institute for Genomic Biology (IGB) at the U of I, Baylor and UC-Davis, is “building on an Illinois tradition” of multidisciplinary cooperation.
The project brings together researchers from microbiology, geobiology, computational chemistry, genomics and physics. The group is interested in “universal biology,” the study of how living matter emerged and evolved. Their findings could have implications for NASA’s search for life elsewhere in the universe.
The research builds on a paradigm-shattering discovery made by Carl Woese, microbiologist and current holder of the Ikenberry Endowed Chair at the U of I. In 1977, he discovered a new domain of life, the Archaea. In doing so, he overturned the dogma that there are only two domains of life, the Eukarya (animals, plants, fungi, and some single-celled organism) and the Prokaryotes (all other organisms).
By analyzing a molecular chronometer, he found two groups within the Prokaryotes, as different from each other as they were from the Eukarya. The Archaea have a simple genetic makeup and, like bacteria, no nucleus. Many thrive under anaerobic conditions or at high temperatures, similar to what has been imagined to be the early environment of Earth.
Woese also hypothesized that life sprang not from a common ancestor but rather, from a loosely knit, diverse conglomeration, or “soup,” of non-cellular entities that he called progenotes. They evolved as a unit and exchanged information between themselves rather than from parent to progeny.
The progenotes became cells and broke into several distinct communities, at which point they could no longer exchange genetic material related to fundamental processes of life. Woese called this the Darwinian Threshold. The communities became the three primary lines of descent: Bacteria, Archaea and Eukarya.
Cann and his collaborators, Gary Olsen and Rachel Whitaker of the U of I, and Scott Dawson of UC-Davis, will look for evidence that progenotes and the Darwinian Threshold existed. They will take components from the DNA replication, transcription and translation machineries of one domain and try to fit them into other domains.
“Isaac has a very special system where he can take components of the replication machinery from the different domains of life and mix and match to see whether they work or not,” explained professor Rod Mackie, who is also part of the NAI project.
A process that accepts a component from another domain has not crossed the threshold, which is why it is still amenable to change. It is evidence of the existence of the threshold and the pre-Darwinian state.
Why work with the Archaea?
“They are storage of a lot of nature’s really brilliant inventions that are not present in bacteria and eukaryotes,” Cann said. “The more we look at them, the more we see the excellence of nature.”
Mackie, U of I professors Bruce Fouke (geology) and Charles Werth (civil engineering), and Susan Rosenberg and Philip Hastings from Baylor College of Medicine (molecular and human genetics) are exploring how cells respond to their environments. This question is important for astrobiology because it dictates the nature and speed of evolution and may be a factor in assessing new forms of life that are discovered elsewhere.
They use a geobiocell, a microfluidic device in which they can establish steep environmental gradients under controlled conditions. The device allows them to look at changes in a very small place at a very rapid pace, making it easier to see how the genomes of cells and simple communities respond to changes in their environment.
Cann and Mackie hope their research will shed light on molecular processes that we do not fully understand now.
ACES Associate Dean of Research Neal Merchen said, “The contributions of Professors Cann and Mackie to this project illustrate the tremendous breadth of impactful research carried out by ACES faculty and the engagement of our scientists in teams that are addressing the biggest questions in biology.”
In addition to the research, the project includes an educational/public outreach component, growing out of initiatives led by Fouke at IGB. Cann said the fact that these initiatives were already in place was very important to the success of the grant.
The education component includes a middle-school Student Teacher Scientist Partnership (STSP) program with the National Park Service at Yellowstone National Park, web-based videos for middle-school students that will also be used in Sweden, online undergraduate and graduate courses at the College of Liberal Arts and Sciences, and an astrobiology course at the Illinois Osher Lifelong Institute for students ages 50 and older.
From the Dec. 26, 2012-Jan. 1, 2013, issue