'Super Plants' That Resist Drought Created

In what could be the solution to world food crisis, scientists from the Faculty of Biology at Technion University in Haifa have created what they call "super plants" by modifying a longevity hormone in the genes known as zytokinin.

The research has been published in the Proceedings of the National Academy of Sciences of the US, Xinhua reported.

"Let's take a staple food, for example rice, when the photosynthesis ends, the rice stops growing, it's a natural process with every plant," said Technion University Biology professor and president of the Kinneret College Simon Gepstein, who led the research.

"But by extending the juvenile hormone, we have managed to extend the life of the plant, therefore producing more crops."

In plants, ageing comes about when zytokinin levels drops, so the researchers prevented the breakdown of the juvenile hormone and made it stay higher for a longer period, preventing the ageing.

"We not only extended the plant's life and managed to make it yield more, but we have also extended the shelf life of the vegetables and fruits it gives," Gepstein said.

"The vegetables and fruits now last double and sometimes three times more after they are cut if they come from the genetically modified plants. I took a modified lettuce home and it took 21 days for it to start getting brown, whereas normal lettuces go bad in five or six days," he said.

Gepstein believes the super plants can be the solution for food shortage in the world, not only because the plants live longer and give more vegetables that can last more on the shelf, but also because they hardly need any water.

"These plants can survive droughts, they can go on for a month without water and even if you water them, they only need 30 percent the amount of liquid normal plants do," he said.

Gepstein discovered this feature of his genetically modified plants by sheer chance, when he forgot to water them for a few weeks.

"We found out that after a month of not getting any water they were as good as when they do get it, so we could take their seeds to arid zones or areas where there is severe drought risks and feed the population with them," the researcher said.

His team is now exploring other possible features these "super plants" may have, like their resilience to pests and parasites and heat as well as cold.

"Despite all the bad the word 'genetically modified' has, I can tell our plants are not dangerous for human health, because we have altered them using their own components, they have nothing added to them," Gepstein said.

Currently, the researcher said, seed companies from all over the world are running field tests with the seeds to verify that these plants can grow outdoors as well, as they did in the greenhouses of Technion University.

"If all goes well, we may be able to see these super plants growing in fields worldwide," Gepstein said.

Source-IANS

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'Human Liver' from Stem Cells Created

by Sheela Philomena on? July 04, 2013 at 11:43 AM Genetics & Stem Cells News Scientists have created human liver tissue from stem cells. Creating lab-grown tissue to replenish organs damaged by accident or disease is a Holy Grail for the pioneering field of research into the premature cells known as stem cells.
Now Takanori Takebe of the Yokohama City University Graduate School of Medicine and a team report in the journal Nature that they grew tissue "resembling the (human) adult liver" in a lab mouse.

They first created induced pluripotent stem (iPS) cells which they mixed with other cell types and coaxed into "liver buds" -- the precursor clusters that develop into a liver.

The buds, each about five millimetres (0.2 inches) big, were then transplanted onto a mouse brain, where they were observed transforming into a "functional human liver" complete with blood vessels, the scientists wrote.

"To our knowledge, this is the first report demonstrating the generation of a functional human organ from pluripotent stem cells," said the report.

The technique has yet to be tested in humans, but serves as an important proof of concept, it added.

Stem cells are infant cells that can develop into any part of the body.

Until a few years ago, when iPS cells were created, the only way to obtain stem cells was to harvest them from human embryos.

This is controversial because it requires the destruction of the embryo, a process to which religious conservatives and others object.

iPS cells are easily-obtainable mature cells that are "reprogrammed" into a versatile, primitive state from where they can develop into any kind of cell in the body.

Takebe told a press conference ahead of the report's release that the man-made liver was observed through a replacement glass skull that was fitted around the mouse's brain.

The liver developed blood vessels which fused with those of the animal.

It also performed certain human-specific liver functions -- producing proteins and processing specific drugs.

"We have concluded that this liver is functioning," the scientist said. "We think this is enough for improving the survival after liver failure."

Scientists commenting on the research described it as promising.

"This science opens up the distinct possibility of being able to create mini-livers from the skin cells of a patient dying of liver failure," said Malcolm Alison, professor of stem cell biology at the Queen Mary University of London.

"Human mature liver cells transplanted on their own can fail to thrive, but if immature liver cells are first combined with their normally nurturing supportive cells, they can mature in the transplanted host and function efficiently," he said in a statement issued by the Science Media Centre.

Dusko Ilic from Kings College London said "the promise of an off-shelf-liver seems much closer than one could hope even a year ago", but the strategy has yet to be proven in humans.

"Whilst the title of the paper is 'functional human liver', these liver buds do not contain the biliary structures (which drain toxins out of the liver) or immune cells that characterise real human liver," added Stuart Forbes, professor of transplantation and regenerative medicine at the University of Edinburgh.

Chris Mason of University College London said the buds may be useful for drug testing in the lab, which is currently restricted by the limited availability of liver cells from human cadavers.

Takebe said the method may also work in organs like the pancreas, kidneys or lungs, but it would be another 10 years before trials are done in humans.

One key requirement would be to shrink the "buds" to a much smaller size so they can be injected into the bloodstream and taken up by the body internally, he said.

Source-AFP

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Artificial Forest Created for Solar Water Splitting

Scientists with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have reported the first fully integrated nanosystem for artificial photosynthesis. While "artificial leaf" is the popular term for such a system, the key to this success was an "artificial forest."

"Similar to the chloroplasts in green plants that carry out photosynthesis, our artificial photosynthetic system is composed of two semiconductor light absorbers, an interfacial layer for charge transport, and spatially separated co-catalysts," explained Peidong Yang, a chemist with Berkeley Lab's Materials Sciences Division, who led this research.

"To facilitate solar water- splitting in our system, we synthesized tree-like nanowire heterostructures, consisting of silicon trunks and titanium oxide branches. Visually, arrays of these nanostructures very much resemble an artificial forest," he said.

Solar technologies are the ideal solutions for carbon-neutral renewable energy - there's enough energy in one hour's worth of global sunlight to meet all human needs for a year. Artificial photosynthesis, in which solar energy is directly converted into chemical fuels, is regarded as one of the most promising of solar technologies.

A major challenge for artificial photosynthesis is to produce hydrogen cheaply enough to compete with fossil fuels. Meeting this challenge requires an integrated system that can efficiently absorb sunlight and produce charge-carriers to drive separate water reduction and oxidation half-reactions.

"In natural photosynthesis the energy of absorbed sunlight produces energized charge-carriers that execute chemical reactions in separate regions of the chloroplast. We've integrated our nanowire nanoscale heterostructure into a functional system that mimics the integration in chloroplasts and provides a conceptual blueprint for better solar-to-fuel conversion efficiencies in the future," Yang said.

When sunlight is absorbed by pigment molecules in a chloroplast, an energized electron is generated that moves from molecule to molecule through a transport chain until ultimately it drives the conversion of carbon dioxide into carbohydrate sugars. This electron transport chain is called a "Z-scheme" because the pattern of movement resembles the letter Z on its side.

Yang and his colleagues also use a Z-scheme in their system only they deploy two Earth abundant and stable semiconductors - silicon and titanium oxide - loaded with co-catalysts and with an ohmic contact inserted between them.

Silicon was used for the hydrogen-generating photocathode and titanium oxide for the oxygen-generating photoanode. The tree-like architecture was used to maximize the system's performance. Like trees in a real forest, the dense arrays of artificial nanowire trees suppress sunlight reflection and provide more surface area for fuel producing reactions.

"Upon illumination photo-excited electron-hole pairs are generated in silicon and titanium oxide, which absorb different regions of the solar spectrum. The photo-generated electrons in the silicon nanowires migrate to the surface and reduce protons to generate hydrogen while the photo-generated holes in the titanium oxide nanowires oxidize water to evolve oxygen molecules. The majority charge carriers from both semiconductors recombine at the ohmic contact, completing the relay of the Z-scheme, similar to that of natural photosynthesis," Yang explained.

Arrays of tree-like nanowires consisting of Si trunks and TiO2 branches facilitate solar water-splitting in a fully integrated artificial photosynthesis system.

Under simulated sunlight, this integrated nanowire-based artificial photosynthesis system achieved a 0.12-percent solar-to-fuel conversion efficiency. Although comparable to some natural photosynthetic conversion efficiencies, this rate will have to be substantially improved for commercial use.

However, the modular design of this system allows for newly discovered individual components to be readily incorporated to improve its performance. For example, Yang noted that the photocurrent output from the system's silicon cathodes and titanium oxide anodes do not match, and that the lower photocurrent output from the anodes is limiting the system's overall performance.

A paper describing this research appeared in the journal NANO Letters.

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