Welcome to Sott.net
Mon, 29 Aug 2016
The World for People who Think

Science & Technology


DNA and not RNA is the main repository of genetic information

© Huiqing Zhou, Duke University
The DNA double helix (shown on the left) can contort itself into different shapes to absorb chemical damage to the basic building blocks (A, G, C and T, depicted by a black dot) of genetic code. In contrast, an RNA double helix (shown on the right) is so rigid and unyielding that rather than accommodating damaged bases, it falls apart completely.
Durham, NC - A new study could explain why DNA and not RNA, its older chemical cousin, is the main repository of genetic information. The DNA double helix is a more forgiving molecule that can contort itself into different shapes to absorb chemical damage to the basic building blocks -- A, G, C and T -- of genetic code. In contrast, when RNA is in the form of a double helix it is so rigid and unyielding that rather than accommodating damaged bases, it falls apart completely.

The research, published August 1, 2016 in the journal Nature Structural and Molecular Biology, underscores the dynamic nature of the DNA double helix, which is central to maintaining the stability of the genome and warding off ailments like cancer and aging. The finding will likely rewrite textbook coverage of the difference between the two purveyors of genetic information, DNA and RNA.

"There is an amazing complexity built into these simple beautiful structures, whole new layers or dimensions that we have been blinded to because we didn't have the tools to see them, until now," said Hashim M. Al-Hashimi, Ph.D., senior author of the study and professor of biochemistry at Duke University School of Medicine.

DNA's famous double helix is often depicted as a spiral staircase, with two long strands twisted around each other and steps composed of four chemical building blocks called bases.

Each of these bases contain rings of carbon, along with various configurations of nitrogen, oxygen, and hydrogen. The arrangement of these atoms allow G to pair with C and A to pair with T, like interlocking gears in an elegant machine.

When Watson and Crick published their model of the DNA double helix in 1953, they predicted exactly how these pairs would fit together. Yet other researchers struggled to provide evidence of these so-called Watson-Crick base pairs. Then in 1959, a biochemist named Karst Hoogsteen took a picture of an A-T base pair that had a slightly skewed geometry, with one base rotated 180 degrees relative to the other. Since then, both Watson-Crick and Hoogsteen base pairs have been observed in still images of DNA.

Five years ago, Al-Hashimi and his team showed that base pairs constantly morph back and forth between Watson-Crick and the Hoogsteen configurations in the DNA double helix. Al-Hashimi says that Hoogsteen base pairs typically show up when DNA is bound up by a protein or damaged by chemical insults. The DNA goes back to its more straightforward pairing when it is released from the protein or has repaired the damage to its bases.

"DNA seems to use these Hoogsteen base pairs to add another dimension to its structure, morphing into different shapes to achieve added functionality inside the cell," said Al-Hashimi.


Giant stellar void in the center of the Milky Way

© University of Tokyo
An artist's impression of the implied distribution of young stars, represented here by Cepheids shown as blue stars, plotted on the background of a drawing of the Milky Way. With the exception of a small clump in the Galactic center, the central 8,000 light years appear to have very few Cepheids, and hence very few young stars.
A major revision is required in our understanding of our Milky Way Galaxy according to an international team led by Prof Noriyuki Matsunaga of the University of Tokyo. The Japanese, South African and Italian astronomers find that there is a huge region around the centre of our own Galaxy, which is devoid of young stars. The team publish their work in a paper in Monthly Notices of the Royal Astronomical Society.

© University of Tokyo
An artist's illustration of the Milky Way, the galaxy we live in, with the locations of the newly discovered Cepheid stars marked by the yellow points. The previously known objects, located around the sun (marked by a red cross), are indicated by small white dots. The central green circle around the core of the galaxy marks the location of the 'Cepheid desert.
The Milky Way is a spiral galaxy containing many billions of stars with our Sun about 26,000 light years from its centre. Measuring the distribution of these stars is crucial to our understanding of how our Galaxy formed and evolved. Pulsating stars called Cepheids are ideal for this. They are much younger (between 10 and 300 million years old) than our Sun (4.6 billion years old) and they pulsate in brightness in a regular cycle. The length of this cycle is related to the luminosity of the Cepheid, so if astronomers monitor them they can establish how bright the star really is, compare it with what we see from Earth, and work out its distance.

Despite this, finding Cepheids in the inner Milky Way is difficult, as the Galaxy is full of interstellar dust which blocks out light and hides many stars from view. Matsunaga's team compensated for this, with an analysis of near-infrared observations made with a Japanese-South African telescope located at Sutherland, South Africa. To their surprise they found hardly any Cepheids in a huge region stretching for thousands of light years from the core of the Galaxy.


Scientists identify brain regions affected by hypnosis

© Karl Birrane/Flickr
The power of hypnotic trance to alter your mind and body is due to changes in a few specific areas of the brain, researchers at the Stanford University School of Medicine have discovered.

The scientists scanned the brains of 57 people during guided hypnosis sessions similar to those that might be used clinically to treat anxiety, pain or trauma. Distinct sections of the brain have altered activity and connectivity while someone is hypnotized, they report in Cerebral Cortex.

Senior author David Spiegel, MD, professor and associate chair of psychiatry and behavioral sciences, said:


Russian scientists developing magnetic 3D bioprinter for radiation-monitoring experiments on the ISS

© 3D Bioprinting Solutions / YouTube
Russian scientists in cooperation with the national space agency are developing a magnetic 3D bioprinter that will allow production of living tissue in the micro-gravity conditions of the International Space Station.

The unique technology will be developed in partnership between the United Rocket and Space Corporation, part of the Roscosmos and 3D Bioprinting Solutions, a resident of the Skolkovo Innovation Center.

"The development of a magnetic bioprinter will allow printing tissue and organ constructs which are hypersensitive to the effects of space radiation - sentinel-bodies (eg, thyroid gland) - for biomonitoring of the negative effect of cosmic radiation in the conditions of a prolonged stay in space and for the development of the preventive countermeasures," 3D Bioprinting Solutions said in a press release after signing a contract with the space corporation on Monday.

The scientific team hopes to send the "unique" technology to the ISS by 2018. Scientists envision that in the long term the newly designed bioprinter could potentially be used to correct astronauts' damaged tissues and organs during long space flights. In addition, the company says the new technology could be used on Earth for the "faster" printing of human tissue and organs to save people's lives.

Announcing the new partnership, the United Rocket and Space Corporation's Director General, has called the endeavor "one more step" that will aid "human exploration of other planets." His colleague, the managing partner of the 3D Bioprinting Solutions, Youssef Hesuani believes that the technology will offer a "unique opportunity" to pursue "new approaches in tissue engineering and regenerative medicine."


How did anthrax suddenly flare up in Siberia?

© REUTERS/ Center for Disease Control

Hot days and melting permafrost

In Russia last week several cases of anthrax were reported in a nomadic reindeer herding community. Eight people have been formally diagnosed with the disease and one 12-year-old boy has died.

Anthrax today is commonly thought of as a biological weapon, but anthrax isn't man-made. The disease, caused by a bacteria, shows up in oblique references in written texts as early as 1250 BC. The bacteria occurs naturally in soil, only becoming dangerous when they enter the body of a human or animal, where they multiply, producing a toxin that can cause a host of unpleasant and deadly symptoms ranging from blisters through high fevers, chills, shortness of breath, and nausea.

It can be treated with antibiotics, and is not contagious, but can be spread when people come in contact with infected livestock or products like meat or animal skins that originate from infected animals.

The sudden spike in Siberian anthrax cases has roots in 1941, when the last outbreak happened in the area. Researchers believe that this year's record-breaking stretch of warm temperatures has contributed to melting permafrost, the previously permanently frozen layer of soil in the tundra.

Comment: The recent anthrax outbreak occurred in the Yamal peninsula, where massive craters were discovered a few years ago. Could there be a correlation? See also:


Unfair fight? F-35 jet's super stealth technology makes training drills tough

© Flickr/ US Air Force
The F-35's many flaws have been well documented. But according to pilots, one aspect of the fifth-generation fighter works so well that it's actually causing new problems.

After months of delays, the US Air Force is expected to deem its F-35 variant combat ready this week. That status means that the fighters are undergoing new exercises to test the plane's capabilities and prepare pilots.

But the aircraft's state-of-the-art stealth technology is evidently making it difficult for the military to carry out those drills. Exercises performed at Mountain Home Air Force Base in Idaho were meant to test the plane's ability to evade surface-to-air missiles [SAM], but ground units had a difficult time locking onto the aircraft.

"If they never saw us, they couldn't target us," said Lt. Col. George Watkins, according to Defense News.


Rotary engine technology can be found in living cells

These miniature rotary motors measure a mere 20 x 10 nanometers (billionths of a meter) yet spin at up to 42,000 rpm (see here), generating 3 ATP per revolution.
Gone are the days when evolutionists asserted that life would never produce wheels or gears. It was impossible, they thought, for structures like that to arrive by natural selection, because too many coordinated mutations would be required. A wheel without an axle would provide no fitness advantage. One gear could achieve nothing without a matching gear. That was before we learned about the planthopper with its gear-driven jumping feet and the exquisite rotary engines of cells: the bacterial flagellum and the ATP synthase motor, on which all life depends.

Since ATP synthase earned its discoverers a Nobel Prize in 1997, it has remained an object of fascination. New imaging techniques have been steadily improving the focus on these miniature rotary motors that measure a mere 20 x 10 nanometers (billionths of a meter) yet spin at up to 42,000 rpm (see here), generating 3 ATP per revolution. As some years have passed since we discussed these motors in detail, readers may wish to pause to refresh their memories with our video about these amazing machines (above) before learning about some new discoveries.

Comment: What about the origins of life itself?

Fireball 3

NASA to launch 7-year mission to potential civilization-destroying asteroid "Bennu"

NASA is about to launch a $1 billion 7-year mission to probe asteroid Benny, which may carry the building blocks of organic life, but also has a chance of hitting Earth late in the next century.

"It may be destined to cause immense suffering and death," Dante Lauretta, professor of planetary science at Arizona University and the lead researcher on the OSIRIS-REx mission, told the Sunday Times.

Comment: Perhaps asteroid Bennu has "friends" that we haven't sighted yet.


Scientists design solar cell that produces burnable fuel from carbon dioxide and sunlight

© University of Illinois at Chicago/Jenny Fontaine
Simulated sunlight powers a solar cell that converts atmospheric carbon dioxide directly into syngas.
Researchers at the University of Illinois at Chicago have engineered a potentially game-changing solar cell that cheaply and efficiently converts atmospheric carbon dioxide directly into usable hydrocarbon fuel, using only sunlight for energy.

The finding is reported in the July 29 issue of Science and was funded by the National Science Foundation and the U.S. Department of Energy. A provisional patent application has been filed.

Unlike conventional solar cells, which convert sunlight into electricity that must be stored in heavy batteries, the new device essentially does the work of plants, converting atmospheric carbon dioxide into fuel, solving two crucial problems at once. A solar farm of such "artificial leaves" could remove significant amounts of carbon from the atmosphere and produce energy-dense fuel efficiently.

"The new solar cell is not photovoltaic -- it's photosynthetic," says Amin Salehi-Khojin, assistant professor of mechanical and industrial engineering at UIC and senior author on the study.


Roscosmos prepares to explore Jupiter's moon Ganymede

© Wikipedia
Russia's space agency Roscosmos intends to send an orbiter and a lander to Jupiter within the next 10 years.

The main goal of the project is to explore Jupiter's moon Ganymede for the existence of primitive life forms.