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Tuesday, 20 October 2009

(Bio)technology, October, 2009

First a cool video.

Here's a quote of the article:"

As it processes information, the brain often synchronises large groups of neurons to fire at the same frequency, a process called "phase-locking". Like broadcasting different radio stations at different frequencies, this allows different "task forces" of neurons to communicate among themselves without interference from others.

The brain also constantly reorganises its task forces, so the stable periods of phase-locking are interspersed with unstable periods in which the neurons fire out of sync in a blizzard of activity.

He found that the length of time the children's brains spent in both the stable phase-locked states and the unstable phase-shifting states correlated with their IQ scores. For example, phase shifts typically last 55 milliseconds, but an additional 1 millisecond seemed to add as many as 20 points to the child's IQ. A shorter time in the stable phase-locked state also corresponded with greater intelligence - with a difference of 1 millisecond adding 4.6 IQ points to a child's score.

Thatcher, meanwhile, has found that certain regions in the brains of people with autism spend less time than average in the unstable, phase-shifting states. These abnormalities reduce the capacity to process information and, suggestively, are found only in the regions associated with social behaviour."
Very very interesting!
  1. Salamanders, regenerative wonders, heal like mammals, people
  2. Printable batteries
  3. One step closer to an artificial nerve cell
  4. Human sperm created from embryonic stem cells (Update)
  5. Researchers enlist DNA to bring carbon nanotubes' promise closer to reality
Short stories:
  1. Discovery pinpoints new connection between cancer cells, stem cells
  2. Nanopillars Promise Cheap, Efficient, Flexible Solar Cells

Salamanders, regenerative wonders, heal like mammals, people

July 1st, 2009
The salamander is a superhero of regeneration, able to replace lost limbs, damaged lungs, sliced spinal cord -- even bits of lopped-off brain. But it turns out that remarkable ability isn't so mysterious after all -- suggesting that researchers could learn how to replicate it in people.

Scientists had long credited the diminutive amphibious creature's outsized capabilities to "pluripotent" cells that, like human , have the uncanny ability to morph into whatever appendage, organ or tissue happens to be needed or due for a replacement.

But in a paper set to appear Thursday in the journal Nature, a team of seven researchers, including a University of Florida zoologist, debunks that notion. Based on experiments on genetically modified axolotl salamanders, the researchers show that cells from the salamander's different tissues retain the "memory" of those tissues when they regenerate, contributing with few exceptions only to the same type of tissue from whence they came.

Standard mammal stem cells operate the same way, albeit with far less dramatic results -- they can heal wounds or knit bone together, but not regenerate a limb or rebuild a spinal cord. What's exciting about the new findings is they suggest that harnessing the salamander's regenerative wonders is at least within the realm of possibility for human medical science.

Also, the salamanders heal perfectly, without any whatsoever, another ability people would like to learn how to mimic, Maden said.

Axolotl salamanders, originally native to only one lake in central Mexico, are evolutionary oddities that become sexually reproducing adults while still in their larval stage. They are useful scientific models for studying because, unlike other salamanders, they can be bred in captivity and have large embryos that are easy to work on.

When an axolotl loses, for example, a leg, a small bump forms over the injury called a blastema. It takes only about three weeks for this blastema to transform into a new, fully functioning replacement leg -- not long considering the animals can live 12 or more years.

The cells within the blastema appear embryonic-like and originate from all tissues around the injury, including the cartilage, skin and muscle. As a result, scientists had long believed these cells were pluripotential -- meaning they came from a variety of sites and could make a variety of things once functioning in their regenerative mode.

Maden and his colleagues at two German institutions tested that assumption using a tool from the transgenic kit: the GFP protein. When produced by genetically modified cells, GFP proteins have the useful quality of glowing livid green under ultraviolet light. This allows researchers to follow the origin, movement and destination of the genetically modified cells.

The researchers experimented on both adult and embryonic salamanders.

With the embryos, the scientists grafted transgenic tissue onto sites already known to develop into certain body parts, then observed how and where the cells organized themselves as the embryo developed. This approach allowed them to see, literally, what tissues the transgenic tissue made. In perhaps the most vivid result, the researchers grafted GFP-modified nerve cells onto the part of the embryo known to develop into the nervous system. Once the creatures developed, ultraviolet light exams of the adults revealed the GFP cells stretched only along nerve pathways -- like glowing green strings throughout the body.

The researchers' main conclusion: Only 'old' muscle cells make 'new' muscle cells, only old skin cells make new skin cells, only old nerve cells make new nerve cells, and so on. The only hint that the axolotl cells could revamp their function came with skin and cartilage cells, which in some circumstances seemed to swap roles, Maden said.

Maden said the findings will help researchers zero in on why salamander cells are capable of such remarkable regeneration. "If you can understand how they regenerate, then you ought to be able to understand why mammals don't regenerate," he said. source

My comment: Wow, that is absolutely amazing. I didn't know that salamanders are such little heroes (wink to Russia). Sure we would like to be able to restore our bodies like them. If you think about it, all the creatures around us are like the Natures laboratory. All kind of genes are mixed in them leading to all kind of great results. We only have to choose what we like and see how to reproduce it. I so hope I'll be able to see one day the full power of this approach. Because it really IS possible to grow a limb and so on. We still have those stem cells in our bodies - the cells from which our bodies grew from first of all. So if we have them, the only problem is how to make them to work for us. It shouldn't be that hard, right? If someone can cure from cancer, then anyone should be able to do it. We have more or less the same hardware. Only the software differs.

Printable batteries

July 2nd, 2009

For a long time, batteries were bulky and heavy. Now, a new cutting-edge battery is revolutionizing the field. It is thinner than a millimeter, lighter than a gram, and can be produced cost-effectively through a printing process.

It was developed by a research team led by Prof. Dr. Reinhard Baumann of the Fraunhofer Research Institution for Electronic Nano Systems ENAS in Chemnitz together with colleagues from TU Chemnitz and Menippos GmbH. "Our goal is to be able to mass produce the batteries at a price of single digit cent range each," states Dr. Andreas Willert, group manager at ENAS.

The characteristics of the battery differ significantly from those of conventional batteries. The printable version weighs less than one gram on the scales, is not even one millimeter thick and can therefore be integrated into bank cards, for example. The battery contains no mercury and is in this respect environmentally friendly. Its voltage is 1.5 V, which lies within the normal range.

By placing several batteries in a row, voltages of 3 V, 4.5 V and 6 V can also be achieved. The new type of battery is composed of different layers: a and a manganese , among others. Zinc and manganese react with one another and produce electricity.

The batteries are printed using a silk-screen printing method similar to that used for t-shirts and signs. At the end of this year, the first products could possibly be finished. source

My comment: Nice. I don't know what is the use of this small batteries, but I'm sure that more creative than me people will figure something out. Something fancy and flashy. And shiny. Lol :)

One step closer to an artificial nerve cell

July 6th, 2009

(PhysOrg.com) -- Scientists at Karolinska Institutet and Linköping University (Sweden) are well on the way to creating the first artificial nerve cell that can communicate specifically with nerve cells in the body using neurotransmitters.

The methods that are currently used to stimulate in the nervous system are based on electrical stimulation. Examples of this are cochlear implants, which are surgically inserted into the cochlea in the inner ear, and electrodes that are used directly in the brain. One problem with this method is that all cell types in the vicinity of the electrode are activated, which gives undesired effects.

Scientists have now used an electrically conducting plastic to create a new type of "delivery electrode" that instead releases the neurotransmitters that use to communicate naturally. The advantage of this is that only neighbouring cells that have receptors for the specific , and that are thus sensitive to this substance, will be activated.

The scientists demonstrate in the article in Nature Materials that the delivery can be used to control the hearing function in the brains of .

The scientists intend to continue with the development of a small unit that can be implanted into the body. It will be possible to program the unit such that the release of neurotransmitters takes place as often or as seldom as required in order to treat the individual patient. Research projects that are already under way are targeted towards hearing, epilepsy and Parkinson's disease.source

My comment: Another very cool thing. I won't comment more, it's obvious this is good research and it will become even better when it reaches people with such needs.

Human sperm created from embryonic stem cells

July 8th, 2009
PhysOrg.com) -- Human sperm have been created using embryonic stem cells for the first time in a scientific development which will lead researchers to a better understanding of the causes of infertility.

Researchers led by Professor Karim Nayernia at Newcastle University and the NorthEast England Stem Cell Institute (NESCI) have developed a new technique which has made the creation of human possible in the laboratory.

Professor Nayernia says: "This is an important development as it will allow researchers to study in detail how sperm forms and lead to a better understanding of in men - why it happens and what is causing it. This understanding could help us develop new ways to help couples suffering infertility so they can have a child which is genetically their own."

"It will also allow scientists to study how cells involved in reproduction are affected by toxins, for example, why young boys with leukaemia who undergo chemotherapy can become infertile for life - and possibly lead us to a solution."

The team also believe that studying the process of forming sperm could lead to a better understanding of how are passed on.

In the technique developed at Newcastle, stem cells with XY chromosomes (male) were developed into germline stem cells which were then prompted to complete meiosis - cell division with halving of the chromosome set. These were shown to produce fully mature, sperm called scientifically, In Vitro Derived sperm (IVD sperm).

In contrast, stem cells with XX chromosomes (female) were prompted to form early stage sperm, spermatagonia, but did not progress further. This demonstrates to researchers that the genes on a are essential for meiosis and for sperm maturation.

The IVD sperm will not and cannot be used for fertility treatment. As well as being prohibited by UK law, the research team say fertilization of human eggs and implantation of embryos would hold no scientific merit for them as they want to study the process as a model for research.

These results indicated maturation of the primordial germ cells to haploid male gametes - called IVD sperm - characterised by containing half a chromosome set (23 chromosomes). source

My comment: I don't understand why it is prohibited by UK law to use this sperm for fertility treatment. It's either good sperm or it is not. And the only way to check this is by studying it for as far as it goes and then using it on eggs to see if it will create viable embryos. And if everything is ok, why not use it to help infertile men to have children? What is wrong with this? It's not cloning since there still will be egg of a woman. It's just artificial sperm!

Researchers enlist DNA to bring carbon nanotubes' promise closer to reality

July 8th, 2009

A team of researchers from DuPont and Lehigh University has reported a breakthrough in the quest to produce carbon nanotubes (CNTs) that are suitable for use in electronics, medicine and other applications.

In an article published in the July 9 issue of Nature, the group says it has developed a DNA-based method that sorts and separates specific types of CNTs from a mixture.

CNTs are long, narrow cylinders of graphite with a broad range of electronic, thermal and structural properties that vary according to the tubes' shape and structure. This versatility gives CNTs great promise in electronics, lasers, sensors and biomedicine, and as strengthening elements in .

Current methods of producing CNTs yield mixtures of tubes with different diameters and symmetry, or "chirality." Before the tubes can be used, however, they must be disentangled from a mixture and "purified" into separate species of CNTs of the same electronic type.

"A systematic method of purifying every single-chirality species of the same electronic type from a synthetic mixture of single-walled nanotubes is highly desirable," the DuPont-Lehigh group wrote in Nature, "but the task has proven to be insurmountable to date."

In 2003, a team of scientists from DuPont, MIT and the University of Illinois at Urbana-Champaign developed a new method of separating metallic CNTs from semiconducting CNTs using single-stranded DNA and anion-exchange chromatography. The scientists reported their discovery in Science. The team was led by Zheng and Jagota, who was then a research scientist with DuPont. The new results improve on the 2003 results by identifying more than 20 DNA short sequences that can recognize individual types, or species, of carbon nanotubes and purify them from a mixture.

The new method utilizes tailored and "allows the purification of all 12 major single-chirality semiconducting species from a synthetic mixture, with sufficient yield for both fundamental studies and application development."

"The interesting discovery made by Tu and Zheng," says Jagota, "is that if you choose the DNA sequence correctly, it recognizes a particular type of CNT and enables us to sort that variety cleanly. This kind of practical improvement brings us closer to manufacturing possibility."

How does DNA recognize and sort types of CNTs? The DuPont-Lehigh team says this could be related to DNA's ability to form a structure different from its usual double helix by wrapping around the CNTs.

An alpha helix, like scotch tape wrapped around a pencil to form a tube, is a common shape seen in proteins, one of the main classes of biological molecules. Another common structure seen in proteins is the beta sheet. If you take a long strand in your palm, stretch it out to the tip of your index finger, loop it to your middle finger, then back to your palm, then out to your ring finger, back to your palm and out to your little finger, you form a type of beta sheet.

"Such a structure is not known for DNA," says Jagota, "but we've shown that it is possible as long as you allow the DNA to adsorb on a surface. If the surface is cylindrical, like a CNT, you get a variant called the beta-barrel."

While the researchers do not have absolute proof, they say circumstantial evidence strongly supports their hypothesis that the DNA is forming this well-organized structure and that it recognizes a specific CNT in the same way that biological molecules recognize each other by structure.source

My comment: That is so freaking interesting. It seems that DNA is extremely useful for all kind of things. I think we're just starting to discover the power of the biological machines in our bodies.

Short stories....

Discovery pinpoints new connection between cancer cells, stem cells

July 1st, 2009

A molecule called telomerase, best known for enabling unlimited cell division of stem cells and cancer cells, has a surprising additional role in the expression of genes in an important stem cell regulatory pathway, say researchers at the Stanford University School of Medicine. The unexpected finding may lead to new anticancer therapies and a greater understanding of how adult and embryonic stem cells divide and specialize.

"Telomerase is the factor that accounts for the unlimited division of cancer cells," said Steven Artandi, MD, PhD, associate professor of hematology, "and we're very excited about what this connection might mean in human disease."

In many ways, telomerase is the quintessential molecule of mystery — hugely important and yet difficult to pin down. Telomerase was known to stabilize telomeres, special caps that protect the ends of . It stitches short pieces of DNA on these chromosome ends in and some , conferring a capacity for unlimited cell division denied to most of the body's other cells. Its importance is highlighted by the fact that it is inappropriately activated in more than 90 percent of cancer cells, suggesting that drugs or treatments that block telomerase activity may be effective anticancer therapies. However, its vast size, many components and relative rarity — it is not expressed in most of the body's cells — hinder attempts to learn more about it.

Artandi and his lab have spent many years identifying and studying the components of the telomerase complex. In this most recent study, they were following up on a previous finding suggesting that one part, a protein called TERT, was involved in more than just maintaining telomeres. They had discovered that overexpressing TERT in the skin of mice stimulated formerly resting adult stem cells to divide — even in the absence of other telomerase components. "This was a pretty clear hint that TERT was involved in something more than just telomere maintenance," he said.

Artandi and his colleagues recognized that the cells' response to TERT mimicked that seen when another protein, beta-catenin, was overexpressed in mouse skin. Beta-catenin is a component of a vital signaling cascade known as the Wnt pathway, which is important in development, stem cell maintenance and stem cell activation. Stanford developmental biologist and professor Roeland Nusse, PhD, a collaborator on the current study, identified the first Wnt molecule in 1982.In this study, Artandi and his colleagues purified the TERT protein from cultured human cells and found that it was associated with a chromatin-remodeling protein implicated in the Wnt pathway. They showed that overexpression of TERT in the presence of the remodeling protein enhanced the expression of Wnt-inducible genes. Finally, they found that TERT is required for mouse to respond appropriately to Wnt signals and that blocking TERT expression impairs the development of frog embryos.

source


Nanopillars Promise Cheap, Efficient, Flexible Solar Cells

July 9th, 2009

(PhysOrg.com) -- Researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have demonstrated a way to fabricate efficient solar cells from low-cost and flexible materials. The new design grows optically active semiconductors in arrays of nanoscale pillars, each a single crystal, with dimensions measured in billionths of a meter.

A solar cell's basic job is to convert light energy into charge-carrying electrons and "holes" (the absence of an electron), which flow to electrodes to produce a current. Unlike a typical two-dimensional solar cell, a nanopillar array offers much more surface for collecting light. Computer simulations have indicated that, compared to flat surfaces, nanopillar semiconductor arrays should be more sensitive to light, have a greatly enhanced ability to separate electrons from holes, and be a more efficient collector of these charge carriers.

"Unfortunately, early attempts to make based on pillar-shaped semiconductors grown from the bottom-up yielded disappointing results. Light-to-electricity efficiencies were less than one to two percent," says Javey. "Epitaxial growth on single crystalline substrates was often used, which is costly. The nanopillar dimensions weren't well controlled, pillar density and alignment was poor, and the quality of the interface between the semiconductors was poor."

Javey devised a new, controlled way to use a method called the "vapor-liquid-solid" process to make large-scale modules of dense, highly ordered arrays of single-crystal nanopillars.

The efficiency of the test device was measured at six percent, which while less than the 10 to 18 percent range of mass-produced commercial cells is higher than most photovoltaic devices based on nanostructured materials - even though the nontransparent copper-gold electrodes on top of the Javey group's test device cut its efficiency by 50 percent. In future, top contact transparency can easily be improved.

Other factors that greatly affect the efficiency of a 3-D nanopillar-array solar cell include its density and the exposed length of the pillars in contact with the window material. These dimensions are easily optimized in future generations of the device.

Concerned with practical applications as well as theoretical performance, the researchers made a flexible solar cell of the same design. They sheathed the whole solar cell in clear plastic (polydimethylsiloxane) to make a bendable device, which could be flexed with only marginal effect on performance - and no degradation of performance after repeated bending. source




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