Penn State: New clues could help scientists harness the power of photosynthesis


Photsynth 070716 newcluescoul.jpgThis illustration is a model of Chl f synthase, potentially a ChlF dimer, based on the known X-ray structure of the core of the Photosystem II reaction center. Photosystem II is the light-driven enzyme that oxidizes water to produce oxygen …more

Identification of a gene needed to expand light harvesting in photosynthesis into the far-red-light spectrum provides clues to the development of oxygen-producing photosynthesis, an evolutionary advance that changed the history of life on Earth. “Knowledge of how photosynthesis evolved could empower scientists to design better ways to use light energy for the benefit of mankind,” said Donald A. Bryant, the Ernest C. Pollard Professor of Biotechnology and professor of biochemistry and molecular biology at Penn State University and the leader of the research team that made the discovery.

This discovery, which could enable scientists to engineer crop plants that more efficiently harness the energy of the Sun, will be published online by the journal Science on Thursday July 7, 2016.

“Photosynthesis usually ranks about third after the origin of life and the invention of DNA in lists of the greatest inventions of evolution,” said Bryant. “Photosynthesis was such a powerful invention that it changed the Earth’s atmosphere by producing oxygen, allowing diverse and complex life forms—algae, plants, and animals—to evolve.”

The researchers identified the gene that converts chlorophyll a—the most abundant -absorbing pigment used by plants and other organisms that harness energy through —into chlorophyll f—a type of chlorophyll that absorbs light in the far-red range of the light spectrum. There are several different types of chlorophyll, each tuned to absorb light in different wavelengths. Most organisms that get their energy from photosynthesis use light in the visible range, wavelengths of about 400 to 700 nanometers. Bryant’s lab previously had shown that chlorophyll f allows certain cyanobacteria—bacteria that use photosynthesis and that are sometimes called blue-green algae—to grow efficiently in light just outside of the usual human visual range—far-red light (700 to 800 nanometers). The ability to use light wavelengths other than those absorbed by plants, algae, and other cyanobacteria confers a powerful advantage to those organisms that produce chlorophyll f—they can survive and grow when the visible light they normally use is blocked.

New clues could help scientists harness the power of photosynthesis
This illustration shows the newly discovered evolutionary scheme for the type-1 and type-2 reaction centers of photosynthesis. Reaction centers are protein machines that convert light energy into stable reductants that can be used by cells …more

 

“There is nearly as much energy in the far-red and near-infrared light that reaches the Earth from the Sun as there is in visible light,” said Bryant. “Therefore, the ability to extend in plants into this range would allow the plants to more efficiently use the energy from the Sun and could increase plant productivity.”

The gene the researchers identified encodes an enzyme that is distantly related to one of the main components of the protein machinery used in oxygen-producing photosynthesis. The researchers showed that the conversion of chlorophyll a to chlorophyll f requires only this one enzyme in a simple system that could represent an early intermediate stage in the evolution of photosynthesis. Understanding the mechanism by which the enzyme functions could provide clues that enable scientists to design better ways to use light energy.

“There is intense interest in creating as an alternative energy source,” said Bryant. “Understanding the evolutionary trajectory that nature used to create oxygen production in photosynthesis is one component that will help scientists design an efficient and effective system. The difficulty is that photosynthesis is an incredibly complex process with hundreds of components and, until now, there were few known intermediate stages in its evolution. The simple system that we describe in this paper provides a model that can be further manipulated experimentally for studying those early stages in the evolution of photosynthesis.”

By disabling the gene that encodes the enzyme in two cyanobacteria that normally produce chlorophyll f, the researchers demonstrated that the enzyme is required for the production of chlorophyll f. The experiment showed that, without this enzyme, these cyanobacteria could no longer synthesize chlorophyll f. By artificially adding the gene that encodes the enzyme, the researchers also showed that this one enzyme is all that is necessary to convert cyanobacteria that normally do not produce chlorophyll f into ones that can produce it.

Another clue that the newly identified enzyme could represent an early stage in the evolution of photosynthesis is that the enzyme requires light to catalyze its reaction and may not require oxygen, as scientists had previously suspected. “Because the enzyme that synthesizes chlorophyll f requires light but may not require oxygen for its activity, it is possible that it evolved before Photosystem II, the photosynthetic complex that produces oxygen and to which the enzyme is related. If the enzyme is an evolutionary predecessor of Photosystem II, then evolution borrowed an enzyme that was originally used for synthesis and used it to evolve an that could produce oxygen, which ultimately led to changes in Earth’s atmosphere,” said Bryant.

Explore further: Hot-spring bacteria reveal ability to use far-red light for photosynthesis

More information: “Light-dependent chlorophyll f synthase is a highly divergent paralog of PsbA of photosystem II,” Science, science.sciencemag.org/cgi/doi/10.1126/science.aaf9178

 

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A new kind of biodegradable computer wood chip – Application: Environmentally Friendly-Flexible (Wearable?) Electronics


Bio Computer Chip 053015 uploaded_1076Portable electronics — typically made of non-renewable, non-biodegradable and potentially toxic materials — are discarded at an alarming rate in consumers’ pursuit of the next best electronic gadget.

In an effort to alleviate the environmental burden of electronic devices, a team of University of Wisconsin-Madison researchers has collaborated with researchers in the Madison-based U.S. Department of Agriculture Forest Products Laboratory (FPL) to develop a surprising solution: a semiconductor chip made almost entirely of wood.
The research team, led by UW-Madison electrical and computer engineering professor Zhenqiang “Jack” Ma, described the new device in a paper published today (May 26, 2015) by the journal Nature Communications. The paper demonstrates the feasibility of replacing the substrate, or support layer, of a computer chip, with cellulose nanofibril (CNF), a flexible, biodegradable material made from wood.
“The majority of material in a chip is support. We only use less than a couple of micrometers for everything else,” Ma says. “Now the chips are so safe you can put them in the forest and fungus will degrade it. They become as safe as fertilizer.”
Zhiyong Cai, project leader for an engineering composite science research group at FPL, has been developing sustainable nanomaterials since 2009.
“If you take a big tree and cut it down to the individual fiber, the most common product is paper. The dimension of the fiber is in the micron stage,” Cai says. “But what if we could break it down further to the nano scale? At that scale you can make this material, very strong and transparent CNF paper.”
“You don’t want it to expand or shrink too much. Wood is a natural hydroscopic material and could attract moisture from the air and expand,” Cai says. “With an epoxy coating on the surface of the CNF, we solved both the surface smoothness and the moisture barrier.”Working with Shaoqin “Sarah” Gong, a UW-Madison professor of biomedical engineering, Cai’s group addressed two key barriers to using wood-derived materials in an electronics setting: surface smoothness and thermal expansion. Gong and her students also have been studying bio-based polymers for more than a decade. CNF offers many benefits over current chip substrates, she says.
“The advantage of CNF over other polymers is that it’s a bio-based material and most other polymers are petroleum-based polymers. Bio-based materials are sustainable, bio-compatible and biodegradable,” Gong says. “And, compared to other polymers, CNF actually has a relatively low thermal expansion coefficient.”
The group’s work also demonstrates a more environmentally friendly process that showed performance similar to existing chips. The majority of today’s wireless devices use gallium arsenide-based microwave chips due to their superior high-frequency operation and power handling capabilities. However, gallium arsenide can be environmentally toxic, particularly in the massive quantities of discarded wireless electronics.
Yei Hwan Jung, a graduate student in electrical and computer engineering and a co-author of the paper, says the new process greatly reduces the use of such expensive and potentially toxic material.
“I’ve made 1,500 gallium arsenide transistors in a 5-by-6 millimeter chip. Typically for a microwave chip that size, there are only eight to 40 transistors. The rest of the area is just wasted,” he says. “We take our design and put it on CNF using deterministic assembly technique, then we can put it wherever we want and make a completely functional circuit with performance comparable to existing chips.”
While the biodegradability of these materials will have a positive impact on the environment, Ma says the flexibility of the technology can lead to widespread adoption of these electronic chips.
“Mass-producing current semiconductor chips is so cheap, and it may take time for the industry to adapt to our design,” he says. “But flexible electronics are the future, and we think we’re going to be well ahead of the curve.”
Source: http://www.news.wisc.edu/23805

What Nano-Science can do to Change our Future for the Better:


Heiner Linke

Heiner Linke is a Professor of Nanophysics and the Deputy Director of the Nanometer Structure Consortium at Lund university. Heiner is talking about the possibilities of nano-science to confront future challenges such as energy conservation and environmentally friendly energy production.