Wyoming Agricultural Experiment Station

UW scientists study how complexity developed from simple cell

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Naomi Ward

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Ekaterina Gottshall

Consider this a matter of scrambling down the family tree to its roots.

Really old roots.

Or perhaps it’s more like blowing the dust off the family album – the human album – and opening to the first pages billions of years ago.

Naomi Ward, an associate professor in the Department of Molecular Biology at the University of Wyoming, is the senior author on a paper recently published in Proceedings of the National Academy of Sciences USA (PNAS).

The research examines how simple bacterial cells could have made the transition to more complex cells, leading to plants, animals and humans.

The paper, “Spatially segregated transcription and translation in cells of the endomembrane-containing bacterium Gemmata obscuriglobus,” was published online this week, and describes research supported by a grant from the National Science Foundation (NSF).

Ekaterina Gottshall, a graduate student in the Molecular and Cellular Life Sciences Ph.D. program, is first author on the paper and main contributor to the experimental work. Other authors are assistant professor Jay Gatlin, also in molecular biology, and Corrine Seebart, an assistant research scientist in Ward’s group.

Ward’s version of genealogy looks at how simple bacterial cells, which do not have the nuclear membrane that separates transcription and translation (the reading of DNA instructions to make protein), could have evolved into eukaryotic cells (plants, animals, humans), which have transcription and translation occurring in separate locations.

This evolutionary step was an important part of developing greater cell complexity in ancient eukaryotic cells.

The membrane-no membrane distinction, and separation of the two processes, serves as a definition.

“This is usually considered to be a very fundamental way in which bacterial cells differ from our cells,” said Ward. “However, cells of Gemmata obscuriglobus (the bacterium they studied) have complex internal membranes, making them look superficially like eukaryotic cells.”

Gottshall wanted to know if transcription and translation could occur in different places in the cell just like in a eukaryote cell.

“We asked this question because the way in which complex eukaryotic cells evolved from a simpler ancestor is not completely understood, and we thought that studying this question in Gemmata might shed some light on that problem,” said Gottshall.

It is generally thought that two of the major membrane-bound compartments in animal and plant cells – mitochondria, the power plants of the cell, and chloroplasts, where photosynthesis occurs – were formed when ancient bacteria took up residence in an ancient proto-eukaryotic cell.

Some estimates place the move-in date around 1.8 billion years ago. Bacterial microfossils first appear about 3.5 billion years ago.

Ward and her research group found a substantial amount of G. obscuriglobus translation does occur in a different place from transcription, as is found in eukaryotic cells.

“Although this is not the first time this has been reported for bacteria, it is the first time it has been reported for such a complex bacterial cell,” said Ward. “Although we don’t know whether this uncoupled gene expression in Gemmata arose in the same way it did in the ancient eukaryotic cell, it shows us one possible way in which it might have been organized.”

The research has yielded another product unusual in molecular biology or other kinds of experimental science.

Ward recently participated in an art-science collaborative experiment (The Ucross-Pollination Experiment), organized by UW philosophy professor Jeff Lockwood. She collaborated with philosophy professor H.L. Hix to explore form in poetry and science, and one of the products was a poem based on the PNAS paper.

Ward believes the poem helps achieve one of the goals of the NSF as well as the Ucross Experiment (supported by the Ucross Foundation and the Wyoming Humanities Council, and a diversity of UW departments and programs), to make science more approachable to non-scientists.

http://www.wyomingextension.org/news/2014/07/15/uw-scientists-study-how-complexity-developed-from-simple-cell/

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