October 06, 2010
SIUC researcher part of NSF ‘tree of life’ project
CARBONDALE, Ill. -- Worms and humans are decidedly different creatures, but a researcher at Southern Illinois University Carbondale is working on a project that he hopes will better define what we both have in common and where each species resides in what scientists call the “tree of life.”
Frank E. Anderson, associate professor of zoology in the College of Science, is a researcher on a five-year, almost $3 million project that is part the National Science Foundation’s “Assembling the Tree of Life” effort. Anderson will focus on sequencing the genes of annelids, a group of animals that includes more than 16,000 species of segmented worms living on land and in water.
Anderson, who will get about $480,000 of the grant to run his part of the study at SIUC, will work with researchers at Auburn University, Colgate University, the Texas A&M University at Galveston and the University of Kansas.
In addition to answering basic biological questions, the study ultimately could help pave the way for advances in medicine as well as help in the search for life on other planets.
Some researchers working on the “tree of life” want to develop a deep understanding of how all living organisms are genetically related, and characterize the single common ancestor they all share.
“We have a name for that ancestor -- the LUCA,” Anderson explained. “It’s an acronym that stands for the Last Universal Common Ancestor.
“The ultimate goal is to get as good an estimate as we can of the entire tree; everything from viruses to mammals,” he said. “We’re all connected evolutionarily. It just depends on how far back you need to go to find what we have in common.”
The researchers’ effort is the next step in the centuries-old quest by scientists to find out who we are biologically.
Scientist know that life in its very simplest form appeared on Earth more than 3 billion years ago, with chemical signs of life dating back even farther than that. About 2 billion years ago, eukaryotes, life that featured cells with nuclei, appeared. More complex creatures, such as animals and fungi, showed up about 1 billion to 600 million years ago.
Scientists in the 18th century began comparing life forms based on anatomical structures, Anderson said. In the late 19th century, Charles Darwin and others began suggesting that all life was connected and shared a common ancestor at some point in the distant past.
In the 1960s and 70s, researchers went far beyond such surface observations, looking at molecules and proteins and ultimately figuring out how to sequence DNA. At the same time, computers that could handle large amounts data were developed, and scientists using them to make comparisons showed that all life forms were related genetically.
The “life tree” effort seeks to better define that big picture.
“When we look at the tree of life, we’re trying to figure out all those relationships,” Anderson said. “To do that, we break it into pieces and try to figure out what’s going on in there, and then how that piece relates to everything else.
“We know some things, but not everything, about what the LUCA was like,” he said. “We want to know, what kind of genes did it have? What was it capable of metabolically? The way you do that is you look at all the life that has derived from that. We can trace back from what organisms have now to that common set of genes.”
In this case, Anderson’s piece of the puzzle involves looking at a few specific genes in the mitochondria in the cells of annelids. Mitochondria, which are known as the “powerhouse of the cell” because they produce energy, are actually bacteria that eukaryotes assimilated at some point in the past.
While Anderson will focus on just a few genes across thousands of annelid species, others on the project will look at many genes for a few annelid species. Researchers hope this tiered approach will allow them to obtain a good genetic cross section of the huge annelid phylum in just a few years.
A key aspect of the study will involve researchers from all over the world in a scientific community-based DNA sequencing project. The researchers are asking fellow scientists everywhere to send Anderson and others interesting samples of annelids for DNA sequencing.
In his laboratory at SIUC, Anderson routinely does such work, turning around a sample in just a couple of days. SIUC doctoral, graduate and undergraduate students will assist in the work, gaining invaluable research experience in the process.
Anderson will enter all the information into a database, which eventually will be joined with other data in an effort to find relationships and commonalities across all life forms.
“We want to tie this together and use that information to tell us how the major groups in the tree are related to each other; “ he said.
While the project is rooted in basic science, it has potential ramifications for other areas, including medicine.
For example, researchers test new drugs on mice, using the mouse as a stand-in for human subjects. From a strictly biological point of view, this makes perfect sense, as mice are extremely similar to humans in important ways, Anderson said.
“But there are important differences too. Some things that work on a mouse may be toxic to humans, so anytime you’re using a model organism you need to know exactly how similar it is to us. A good way to figure that out is a tree that shows just how related they are and what changes occur along the different branches,” he said. “It puts everything in a context, just like we know to test things on a mouse, not a cactus, because a mouse is more similar to us. The tree of life even enhances that idea.”
Along with additional implications for agriculture, forestry and toxicology, the work may also help scientists know what to look for when exploring other planets for signs of life.
“If we know on this planet what life looked like 3.5 billion years ago, it might tell us more about what to look for on Mars or other planets,” he said. “We may find the evolution of life isn’t that hard. We may go out in the universe and find it is filled with life. What may be rare is complex life.”
The project might also give answers and perspective to the age-old question of what makes us human.
“If the tree is ever fully resolved, we theoretically could step down through the branches and see what features our ancestors had,” Anderson said. “We could reconstruct it. We could maybe walk it all the way back to the LUCA. I think that would be of inherent interest.