New Engineered Bacteria becomes a Biofuel Precursor

Research shows using genetic engineering approach, desired products can be produced.

Global population explosion puts us in a very difficult stage where it is very important to have alternatives to modern day fuels like gasoline that fuels million of cars with internal combustion engines as our current biofuels sources are exhaustible. In a recent finding published in PNAS, Scientists at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Department of Systems Biology at Harvard Medical School have engineered a bacterium which is capable of producing biofuel precursors that is reported to have high-octane fatty acid moieties.

The E. coli uses a natural oil production mechanism to convert sugars into fats which are then used in the bacteria’s cell membrane. By genetically altering E. coli, researchers were able to convert the sugars to the imitation fossil fuel. Pamela Silver and her team are focusing on medium-chain fatty acids (MCFA), those with chains between four and 12 carbons long as they are just the right length to be transformed into an energy-packed liquid fuel for internal-combustion engines. Fatty acids with shorter chains do not store enough energy to be good fuels and they tend to vaporize easily, while those with chains longer than 12 carbons are too waxy. Through genetic engineering approach, a drug was used which blocks the enzyme that extends fatty-acid chain synthesis. This led to the production of eight-carbon fatty acid called octanoate which can be converted into octane. Basically, they stopped the usual pathway where addition of carbon atoms leads to build up of long chain fatty acids in the middle such that it only produces MCFA. This led to the buildup of MCFA pool.

Though gasoline produces more energy than current biofuels when burned in an internal combustion engine, and remains liquid in wide temperature range but burning gasoline itself adds huge amounts of carbon dioxide to the atmosphere which is a global concern. The strategy reported in this study should be widely useful in a range of metabolic engineering applications in which essential enzymes divert flux away from a desired product. It will also help in producing precursors of pharmaceuticals, bioplastics, herbicides, detergents, and more.

Source: J. P. Torella, T. J. Ford, S. N. Kim, A. M. Chen, J. C. Way, P. A. Silver. Tailored fatty acid synthesis via dynamic control of fatty acid elongation. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1307129110

Super Sugar Keeps Naked Mole Rats Cancer-Free

Researchers have discovered how nature’s oddest creature has given up the secret of its incredible cancer immunity and longevity.

The naked mole rat, a hairless rodent that lives underground has never been known to get cancer, despite its unusually long 30-year lifespan. Researchers at the University of Rochester, New York have achieved a breakthrough by discovering a chemical compound which is a complex sugar, called hyaluronan that exists between cells in body tissues and helps keeps them from clumping and forming tumors.

Known as high molecular weight hyaluronan, HMW-HA is a part of extracellular matrix of many animals but naked mole rats are unusual in producing it about five times the size found in mice, rats and humans. It has an annoying tendency to clog up vacuum pumps and tubing in the laboratory, that’s when it caught attention.

Researchers tested the role of HMW-HA by removing the gooey substance from naked mole rat cells. As predicted, those rats became susceptible to tumors, thereby suggesting its role in conferring resistance against cancer. The research, published in the journal Nature showed that mole rat hyaluronan activates a powerful anti-cancer gene called p16 which prevents cells proliferation when too many of them crowd together. The important gene HAS2 was responsible for producing high levels of HMW-HA in mole rats owing to production-boosting mutations to the enzyme that synthesizes HA and low activity of the enzyme that degrades the molecule.

Researchers then tried to prompt tumor growth by exposing the mole rats to proteins that cause cancer in mice. Nothing happened until the production of hyaluronan was altered. The biologists speculate that naked mole rats have evolved a higher concentration of HA in the skin to provide skin elasticity needed for life in underground tunnels. This trait may have then been co-opted to provide cancer resistance and longevity to this species.

The finding establishes hyaluronan as a key player in cancer that could lead to exciting new opportunities in cancer treatments for human patients.

Source: Xiao Tian, Jorge Azpurua, Christopher Hine, Amita Vaidya, Max Myakishev-Rempel, Julia Ablaeva, Zhiyong Mao, Eviatar Nevo, Vera Gorbunova, Andrei Seluanov. High-molecular-mass hyaluronan mediates the cancer resistance of the naked mole rat. Nature, 2013; DOI: 10.1038/nature12234

 

How to Trigger the Fruit Growth Hormone

Research shows ethylene is responsible for regulating the action of other hormones in the plant developmental pathways.

If someone told you to put your rock hard green McIntosh apple with a banana as that would make it ripe, you sure would scoff a little. But, believe your ears and do that yourself. It’s an easy way to get that red juicy goodness without spending a single penny! It sounds like magic –  but it’s pure science. A very recent study by scientists from the Salk institute for Biological Studies have published their finding in the online international journal eLIFE – stating that the plant hormone ethylene alone activates thousand of other genes in a plant.

Ethylene is a gaseous plant hormone that acts at trace levels to stimulate or regulate a variety of processes, including the regulation of plant growth, the ripening of fruit and the shedding of leaves. It is also produced in response to wounding or pathogen attack, exposure to environmental signals such as extreme temperature or drought conditions. All these effects are produced by altering the expression of different genes. Although the effects of ethylene on plants are well documented, much less is known about how its many functions are controlled and coordinated at the molecular level. So how does it work?

It was validated in the model plant Arabidopsis thaliana, by performing molecular level studies to see what happens when it is exposed to ethylene gas? What genes are turned on and what they actually do? It was evidenced that ethylene directly activates a protein, known as EIN3 which is a master regulator in ethylene signaling pathway. Scientists used a technique called ChIP-Seq to identify those regions of DNA where EIN3 binds to. And the number was surprising: over a thousand!

Two interesting things were discovered. First, when EIN3 is activated by ethylene, it activates all those genes that activate its own production. Second, it targets all other hormone signaling pathway in plant because half of the genomic targets of the EIN3 protein were found to be in other hormone signaling pathways.

This clearly shows how ethylene genetically controls the intricate signaling and developmental pathways in the plant. The piece of knowledge generated from this study would help in mapping interconnections between the hormone pathways that have implications on agriculture.

 

Reference: Katherine Noelani Chang, Shan Zhong, Matthew T Weirauch, Gary Hon, Mattia Pelizzola, Hai Li, Shao-shan Carol Huang, Robert J Schmitz, Mark A Urich, Dwight Kuo, Joseph R Nery, Hong Qiao, Ally Yang, Abdullah Jamali, Huaming Chen, Trey Ideker, Bing Ren, Ziv (2013). Temporal transcriptional response to ethylene gas drives growth hormone cross-regulation in Arabidopsis eLife