Friday, February 15, 2013

Cellular renewal process may underlie benefits of omega fatty acids

Feb. 13, 2013 ? A search for genes that change their levels of expression in response to nutrient deprivation has uncovered potential clues to the mechanism underlying the health benefits of omega fatty acids. In the Feb. 15 issue of Genes & Development, Massachusetts General Hospital (MGH) researchers describe finding that feeding omega-6 fatty acids to C. elegans roundworms or adding them to cultured human cells activates a cellular renewal process called autophagy, which may be deficient in several important diseases of aging. A process by which defective or worn-out cellular components and molecules are broken down for removal or recycling, autophagy is also activated in metabolically stressful situations, allowing cells to survive by self-digesting nonessential components.

"Enhanced autophagy implies improved clearance of old or damaged cellular components and a more efficient immune response," says Eyleen O'Rourke, PhD, of MGH Molecular Biology, lead author of the report. "It has been suggested that autophagy can extend lifespan by maintaining cellular function, and in humans a breakdown in autophagic function may involved in diseases including inflammatory bowel disease, Parkinson's disease, and in a more complex way in cancer and metabolic syndrome."

O'Rourke is a research fellow in the laboratory of MGH investigator Gary Ruvkun, PhD, whose team investigates the development, longevity and metabolism of C.elegans. Ruvkun and other researchers have discovered that simple mutations in genetic pathways conserved throughout evolution can double or triple the lifespan of C. elegans and that similar mutations in the corresponding mammalian pathways also regulate lifespan. Many of these mutations also make animals resistant to starvation, suggesting that common molecular mechanisms may underlie both response to nutrient deprivation and the regulation of lifespan.

To find these mechanisms O'Rourke searched genomic databases covering many types of animals for shared genes that respond to fasting by changing their expression. She found that expression of the C. elegans gene lipl-4 increases up to seven times in worms not given access to nutrients. A transgenic strain that constantly expresses elevated levels of lipl-4, even when given full access to food, was found to have increased levels of arachidonic acid (AA), an omega-6, and eicosapentanoic acid (EPA), an omega-3 fatty acid and to resist the effects of starvation.

Following the implication that omega fatty acids stimulate a process leading to starvation resistance, the researchers found that feeding AA and another omega-6 fatty acid, but not EPA, activated autophagy in non-transgenic C. elegans with full access to nutrients. Since activation of autophagy has been shown to increase lifespan in several genetic models, the authors tested the effect of omega-6 fatty acids on C. elegans lifespan and found that roundworms consuming a full normal diet supplemented with omega-6 fatty acids lived 20 to 25 percent longer than usual.

Since dietary supplementation with both omega-3 and omega-6 fatty acids has been shown to prevent or improve several human health conditions, the researchers tested the response of cultured human cells to omega fatty acid supplementation. As in C. elegans, the human cells responded to supplementation with the omega-6 acids, but not to EPA, by activation of autophagy, measured by levels of marker proteins. That result suggests that omega-6 acids induce autophagy across the full range of multicellular animal species. The researchers then showed that the lifespan-increasing properties of omega-6 fatty acids in C. elegans depend on the presence of genes required for autophagy.

"Almost all the mechanisms of lifespan extension studied until now -- sterility, insulin insensitivity, and caloric restriction -- have been shown to depend on activation of autophagy," says O'Rourke. "Our finding that omega-6 supplementation activated roundworms' cellular response to fasting -- namely autophagy -- even though the worms were eating normally suggests that consumption of omega-6 fatty acids may provide the benefits of caloric restriction without the need to limit food consumption. It also suggests that the reported benefits of omega-6 acids could depend in part on activation of an evolutionarily ancient program for surviving food deprivation."

O'Rourke and her co-authors note that many investigators and clinicians believe that omega-6 fatty acids -- commonly found in meats, poultry and vegetable oils -- may increase the risk of cardiovascular disease, despite epidemiologic evidence that omega-6 consumption actually reduces cardiovascular risks. "We hope that our findings -- made by investigating the cellular responses of a 1-millimeter roundworm -- will lead the scientific and medical community to look back at all the epidemiologic, basic and clinical research data and to study the effects of omega-6 fatty acids on multiple types of human cells and live animals in order to gain better knowledge on how balanced intake of these nutrients benefits human health," she says.

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The above story is reprinted from materials provided by Massachusetts General Hospital, via EurekAlert!, a service of AAAS.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. E. J. O'Rourke, P. Kuballa, R. Xavier, G. Ruvkun. ?-6 Polyunsaturated fatty acids extend life span through the activation of autophagy. Genes & Development, 2013; DOI: 10.1101/gad.205294.112

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/~3/wtyeik7QzSI/130213152523.htm

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Thursday, January 24, 2013

Dear Prudence: Desperate Single

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New 2-D material for next generation high-speed electronics

Jan. 21, 2013 ? Scientists at CSIRO and RMIT University have produced a new two-dimensional material that could revolutionise the electronics market, making "nano" more than just a marketing term.

The material -- made up of layers of crystal known as molybdenum oxides -- has unique properties that encourage the free flow of electrons at ultra-high speeds.

In a paper published in the January issue of materials science journal Advanced Materials, the researchers explain how they adapted a revolutionary material known as graphene to create a new conductive nano-material.

Graphene was created in 2004 by scientists in the UK and won its inventors a Nobel Prize in 2010. While graphene supports high speed electrons, its physical properties prevent it from being used for high-speed electronics.

The CSIRO's Dr Serge Zhuiykov said the new nano-material was made up of layered sheets -- similar to graphite layers that make up a pencil's core.

"Within these layers, electrons are able to zip through at high speeds with minimal scattering," Dr Zhuiykov said.

"The importance of our breakthrough is how quickly and fluently electrons -- which conduct electricity -- are able to flow through the new material."

RMIT's Professor Kourosh Kalantar-zadeh said the researchers were able to remove "road blocks" that could obstruct the electrons, an essential step for the development of high-speed electronics.

"Instead of scattering when they hit road blocks, as they would in conventional materials, they can simply pass through this new material and get through the structure faster," Professor Kalantar-zadeh said.

"Quite simply, if electrons can pass through a structure quicker, we can build devices that are smaller and transfer data at much higher speeds.

"While more work needs to be done before we can develop actual gadgets using this new 2D nano-material, this breakthrough lays the foundation for a new electronics revolution and we look forward to exploring its potential."

In the paper titled 'Enhanced Charge Carrier Mobility in Two-Dimensional High Dielectric Molybdenum Oxide,' the researchers describe how they used a process known as "exfoliation" to create layers of the material ~11 nm thick.

The material was manipulated to convert it into a semiconductor and nanoscale transistors were then created using molybdenum oxide.

The result was electron mobility values of >1,100 cm2/Vs -- exceeding the current industry standard for low dimensional silicon.

The work, with RMIT doctoral researcher Sivacarendran Balendhran as the lead author, was supported by the CSIRO Sensors and Sensor Networks Transformational Capability Platform and the CSIRO Materials Science and Engineering Division.

It was also a result of collaboration between researchers from Monash University, University of California -- Los Angeles (UCLA), CSIRO, Massachusetts Institute of Technology (MIT) and RMIT.

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The above story is reprinted from materials provided by CSIRO Australia.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Sivacarendran Balendhran, Junkai Deng, Jian Zhen Ou, Sumeet Walia, James Scott, Jianshi Tang, Kang L. Wang, Matthew R. Field, Salvy Russo, Serge Zhuiykov, Michael S. Strano, Nikhil Medhekar, Sharath Sriram, Madhu Bhaskaran, Kourosh Kalantar-zadeh. Enhanced Charge Carrier Mobility in Two-Dimensional High Dielectric Molybdenum Oxide. Advanced Materials, 2013; 25 (1): 109 DOI: 10.1002/adma.201203346

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/matter_energy/technology/~3/iVeA9nSoozs/130122122442.htm

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