‘Extreme’ genes sheds light on origins of photosynthesis

December 15, 2009

While most school children understand that green plants photosynthesize, absorb carbon dioxide and produce oxygen, few people consider the profound global-scale effects that photosynthesis has had on Earth. One of those actively shedding light on the origins and evolution of photosynthesis is Jeffrey Touchman, assistant professor in the School of Life Sciences.

Oxygen, one of the by-products of photosynthesis by microbes such as cyanobacteria and their descendants (including algae and higher plants), transformed the Precambrian Earth and made possible the evolution of more complex organisms. With an $867,000 award from the National Science Foundation and the USDA National Institute of Food and Agriculture, Touchman works to illuminate large gaps in the available genetic data for photosynthetic microbes through the study of phototrophic extremophiles (organisms living in unusually harsh and exotic environments). His research is focused on genome sequencing and molecular analyses of heliobacteria, proteobacteria and a cyanobacterium with the ability to shift into anoxygenic (oxygen-free) photosynthesis in the presence of sulfide, a possible evolutionary “missing link” between anoxygenic and oxygenic photosynthetic organisms. Download Full Image

“Knowing how photosynthesis originated and evolved is essential to obtaining the deep understanding required to yield improvements in bioenergy, agriculture and the environment,” Touchman said.

Touchman, who is also an adjunct investigator at The Translational Genomics Research Institute (TGen), has chosen his photosynthetic, microbial partners carefully; each bears a unique metabolism, physiology or ecology and differs in fundamental ways from sequenced genomes of any other phototroph. Hidden in these organisms’ various genetic codes may be hallmarks: traces of early evolutionary innovations pointing to the origin of oxygen-evolving high-energy photosynthesis.

There are important linkages between Touchman’s work on earthbound origins and astrobiology as well. Phototrophic extremophiles are excellent model microbes for studies of interplanetary photosynthetic exchange, Touchman said. That is, exchange that might come about in stellar systems that have terrestrial-type rocky planets that could be capable of exchanging gneiss and rocky material. The arrival of oxygenic photosynthesis via transport of materials by external means, such as meteorites, could profoundly change the direction of biological evolution on a planet’s surface.

Transpermia or rocky panspermia is the possibility of the exchange of micro-organisms between planets via impact material. Paul Davies, director of ASU’s Beyond Center for Fundamental Concepts in Science, developed some of the thinking upon which Touchman’s extraterrestrial pursuits are based.

"Some micro-organisms can survive interplanetary journeys cocooned inside rocks blasted off planets by comet and asteroid impacts," he said. "That rocky panspermia is an effective mechanism for spreading life within a planetary system.

“Oxygen is a central biosignature or fingerprint of life sought in the atmospheric spectra of planets beyond our solar system. Detailed molecular understanding of how photosynthetic microbes can push the boundaries of extreme-environment existence on our own planet will also fill important gaps in our current understanding of extra-terrestrial potential for oxygen-evolving photosynthesis.”

Touchman’s research is part of a suite of innovative genetic and genetic engineering studies being conducted with cyanobacteria by School of Life Sciences faculty in coordination with the Center for Bioenergy and Photosynthesis in the College of Liberal Arts and Sciences. Most notable of these are translational life science studies to advance bioenergy – biodiesel and biohydrogen studies supported by Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) program funding, headed by professor Willem Vermaas – and work on natural sunscreens by professor Ferran Garcia-Pichel.

Margaret Coulombe

Director, Executive Communications, Office of the University Provost


Three law students named Cohen Professionalism Scholars

December 15, 2009

Vivian Corral-Nava, a first-year student at the Sandra Day O'Connor College of Law, was chosen to be the 2009/2010 Cohen Professionalism Scholar with honorable-mention distinction awarded to two other 1Ls, Ganes McCulloch and Kenneth Moskow.

The presentation of the fifth annual Cohen Professional Scholars competition, designed to address integrity in the legal profession, was made on Wednesday, Nov. 18, in the Great Hall by Maricopa County Superior Court Judge Bruce R. Cohen (Class of 1981) and his wife Loren. Download Full Image

The Cohens sponsor the competition in which the winners receive scholarships and plaques. The students also will accompany the couple on a trip to the Museum of Tolerance in Los Angeles for a private tour.

The Cohens have long recognized the accomplishments and distinction of each member of the entering law class. Cohen noted, however, that "as soon as it is known to others that someone is attending law school and is studying to become an attorney, that person is subjected to ridicule and "lawyer jokes." While students aren't responsible for this less-than-stellar reputation of the legal profession," he said, "they must assume the responsibility for changing the public view by bringing honor to the profession. By instilling that message from the start of their law education, we are hoping that it assists the students in this undertaking."

Cohen said this year's essays were exceptional and the selection process was challenging.

"Each year, when Loren and I review the submissions, our optimism for the future of the legal profession is renewed," he said. "We are always amazed by the breadth of topics covered and insights demonstrated in the essays."

Corral-Nava captured a core concept regarding maintaining integrity. Cohen said she poetically noted that what people do and accomplish in their professional and personal lives is based largely on facing the day's challenges and being prepared to do so on every following day.

Her essay, "Resiliency," focused in an abstract way on the richness and fullness of her experiences, even the moments in which she feels the most defeated and challenged as a law student.

"The most important factor I see contributing to the legal profession is to never quit," Corral-Nava said. "Never give up, and simply choosing to get up each and every day and do it all again is what keeps us grounded."

She said she was surprised to be selected the first-place winner, and that, in the midst of preparing for final exams, facing deadlines and spending long hours in the library, the honor "could not have come at a better time."

To read Corral-Nava's essay, click here.

Cohen">http://www.law.asu.edu/files/Administration/Communication/News/2009/2009... commented that Ganes McCulloch poignantly addressed the difficulty of selecting between just two viable choices, and showed that integrity is not simply measured by choosing between right and wrong. McCulloch's essay, "Ethical Call to Duty," likens a choice made by a young man at a busy international border, where a distraught woman asks him to carry her children's medications across that border, an act that was illegal but necessary.

McCulloch said the best part of being named a Cohen Scholar isn't the recognition or scholarship money, but the chance to meet with the Cohens after the awards ceremony.

"He is a sincere man," McCulloch said of the judge. "One can't help but feel like every word he speaks is truly from his heart. It was a privilege to spend some time conversing with the two of them."

To read McCulloch's essay, click here.

The">http://www.law.asu.edu/files/Administration/Communication/News/2009/2009... Cohens were moved by Moskow's recognition that the small things people do create larger-scale issues.

"If unchecked, minor departures from a proper course of action contribute to the major violations of one's integrity," Cohen said. The essay, "Integrity," references the "broken window theory," which says that when vandals break a window and it's left unfixed, more windows will be broken, vandals will move in and fires will be set. In the same way, small things that fracture our integrity invite bigger things, Moskow wrote.

To read Moskow's essay, click here">http://www.law.asu.edu/files/Administration/Communication/News/2009/Mosk....

Janie Magruder, jane.magruder">mailto:jane.magruder@asu.edu">jane.magruder@asu.edu
(480) 727-9052
Sandra Day O'Connor College of Law