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The approach to predictive medicine that is taking genomics research by storm

The approach to predictive medicine that is taking genomics research by storm | Amazing Science | Scoop.it

Polygenic risk scores represent a giant leap for gene-based diagnostic tests. Here is what they mean for predictive personalized medicine:

 

When researchers completed the first drafts of the human genome in the early 2000s, many expected that it would mark the start of a medical revolution. Geneticists started searching for the differences that might explain why one person develops diabetes or heart disease whereas another does not. The idea was simple: compare a group of people with the condition to a group without and look for differences in their DNA. The variations generally came in the form of DNA-letter swaps, known as single nucleotide polymorphisms, or SNPs. If people with a condition tended to have a T at a certain location whereas others had a C, that suggested that the SNP was associated in some way with the disease.

 

These genome-wide association studies — or GWASs, as they came to be known — became very popular. But after years of searching, scientists could still only explain a small bit of the inherited risk for common diseases. It turned out that most of these conditions were related to many more SNPs than scientists had first expected, says Ali Torkamani, a geneticist at the Scripps Research Institute, La Jolla, California.

 

Worse still, a majority of the variants conferred a very small risk — detectable only when surveying huge groups of people.“We didn’t have the sample size to really drive prediction as well as some people naively thought,” says Ewan Birney, director of the European Bioinformatics Institute in Hinxton, UK. By 2007, geneticists were fretting about something they called “missing heritability”. It was clear that many of these conditions had a genetic component, but GWASs clearly weren’t catching much of it.

 

Today, things are finally changing. With access to massive data sets, as well as advances in how data are analyzed, scientists are getting better at measuring those very small risks. A prime example is the technique geneticist Kathiresan used to generate his 6.6-million SNP score, which was published in August 20181. He and his team took data from a 2015 meta-analysis that combined 48 GWASs, consisting of 61,000 people with coronary artery disease and 120,000 controls2. They then tested their polygenic predictor on 290,000 people in the UK Biobank, finding that those scoring in the highest few percentiles had on average several times higher risk of developing the disease than did the rest of the population. Of the 23,000 people who received the highest scores, for example, 7% had coronary artery disease, compared with 2.7% of the remaining population. The group conducted similar analyses for four other disorders, including inflammatory bowel disease and breast cancer, each time identifying a group who scored in the top few percentiles and were at particularly high risk.

 

Understanding how people will react to polygenic scores is a high priority for researchers. Ripatti and his colleagues have given more than 7,000 individuals in Finland information about their likelihood of developing heart disease, based on both polygenic scores and conventional risk factors such as high blood pressure. Most of the respondents say that getting this information motivates them to make positive changes, says Ripatti. Preliminary results suggest that those with high genetic risk are the most likely to take actions such as losing weight or stopping smoking.

 

In nearby Estonia, researchers are in the process of genotyping 100,000 individuals, adding to the 50,000 the country has already sampled. And unlike many other biobanks, participants in the Estonian project can sign up to receive feedback. Among the results being returned to them are polygenic risk scores for type 2 diabetes and cardiovascular disease, says Lili Milani, a geneticist at the Estonian Genome Center at the University of Tartu, Estonia. Similar to the Finnish work, participants are shown graphs of how lifestyle changes could reduce or increase their risk. And, says Milani, initial indications are that people are glad for the advice.

 

For now, people are receiving their scores from genetic counsellors. But Milani is working with the Estonian government to work out how to integrate genomic data into the health-care system, so that it can be used every day by doctors. The country ultimately aims to genotype anyone who’s interested, right up to its entire population of 1.3 million, Milani says. “The goal is to build something so great that all doctors will want to recommend it and all of the population will want it.”

 

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Human Accelerated Regions (HARs) and Other Human-Specific Sequence Variations in the Context of Evolution and Their Relevance for Brain Development

Human Accelerated Regions (HARs) and Other Human-Specific Sequence Variations in the Context of Evolution and Their Relevance for Brain Development | Amazing Science | Scoop.it

This review article discusses, in a format of a timeline, the studies of different types of genetic variants, present in Homo sapiens, but absent in all other primate, mammalian, or vertebrate species, tested so far. The main characteristic of these variants is that they are found in regions of high evolutionary conservation.

 

These sequence variations include single nucleotide substitutions (called human accelerated regions or HARs), deletions, and segmental duplications. The rationale for finding such variations in the human genome is that they could be responsible for traits, specific to our species, of which the human brain is the most remarkable.

 

As became obvious, the vast majority of human-specific single nucleotide substitutions are found in noncoding, likely regulatory regions. A number of genes, associated with these human-specific alleles, often through novel enhancer activity, were in fact shown to be implicated in human-specific development of certain brain areas, including the prefrontal cortex.

 

Human-specific deletions may remove regulatory sequences, such as enhancers. Segmental duplications, because of their large size, create new coding sequences, like new functional paralogs. Further functional study of these variants will shed light on evolution of our species, as well as on the etiology of neurodevelopmental disorders.

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What Will Earth's Climate Look Like by 2050?

What Will Earth's Climate Look Like by 2050? | Amazing Science | Scoop.it
Spoiler alert: it won't be nice.

 

By 2050, we could be living on a drastically different planet Earth — one that’s much harder to survive on. We’d see higher ocean levels, warmer temperatures, and more extreme weather events.

 

To demonstrate what life on the planet might be like in the future, meteorologists from countries around the world created weather reports of a day in 2050. While the reports were, of course, fictional, they were based on various scientific data. The Brazilian report included rains so heavy in South Brazil and the West Amazon that they surpassed the expected amount of rainfall for the month in a few days. Northern Brazil and the East Amazon, meanwhile, were struggling with drought. Similar, but less drastic, conditions have already occurred in Brazil. In 2014, rainfall from a series of storms over three days was three times higher than the historical average. Eleven people died in the storms.

 

The rest of the predictions involved similarly bleak conditions and included events such as drought, heat waves and hurricanes. They also predicted warmer-than-usual temperatures that would change the ecosystems of the area.

 

Who Will It Impact?

Spoiler alert: everybody on planet Earth. If we hit two degrees of warming by 2050 (which we are well on the way right now), most of the people alive today will experience extreme climate changes (fires, flooding, extreme wind). It would impact everyone, but some areas would feel stronger effects sooner than others.
 
If we decrease our emissions, about 1 billion people could be living in drastically different climates than they are today. If your emissions levels stay where they are now, that number could be as high as 5 billion. Despite the tendency to focus on the Arctic when looking for the impacts of climate change, tropical regions would likely experience significant impacts first. Temperatures in the Arctic historically have varied much more than in the tropics, meaning tropical areas aren’t as prepared to adjust to changing temperatures.
 
Species such as coral reefs are highly temperature-sensitive. They’ve already been bleaching in huge numbers. These reefs serve as the habitats for all sorts of ocean life. If we lost those species, the results would be dramatic. Ocean ecosystems would crumble, and we’d lose fish species that are important food sources and that tropical economies, many of which are already struggling, depend on. As ocean levels rise, coastal cities would eventually have to be evacuated as well, displacing huge amounts of people and placing strains on other parts of the world.

What Can We Do?

Is there anything we can do to stop these catastrophes from occurring? The effects of climate change are already happening, so we can’t stop it entirely. We may, however, be able to slow it down and buy ourselves some time.

 

To slow down climate change, we need to reduce our carbon emissions. Switching from fossil fuels to energy sources that don’t produce greenhouse gas emissions, and replacing gasoline-powered cars with electric cars, would go a long way. We also need to stop deforestation and plant more trees. This list could go on and on. Anything that reduces greenhouse gas emissions will help.

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Genomes of seven animals reveal new parts of the human genome for disease development

Genomes of seven animals reveal new parts of the human genome for disease development | Amazing Science | Scoop.it
To unearth new functional regions in the human genome with potential roles in shaping clinically important traits, researchers searched for how elephants, hibernating bats, orcas, dolphins, naked mole rats, and ground squirrels changed critical parts of the human genome that are shared with most other mammals. These regions are highly conserved, but to evolve their highly distinctive traits, these seven species had to change how these conserved DNA elements work.

 

For example, elephants are the largest land mammals and were discovered to have changed several conserved regions associated with DNA repair. This discovery hints at why elephants rarely get cancer despite their large size and may provide clues to the genetics of human cancer. The study was published March 6 2018 in the journal Cell Reports.

 

"What we've done is use animals with extraordinary traits to reveal new elements in the human genome that we think are important, but were hidden to us before," says senior author Christopher Gregg (Twitter: @GreggNeuroLab), a neuroscientist and geneticist at the University of Utah. "By decoding some of the noncoding parts of the genome, these data sets also revealed traits that you wouldn't have thought about in relation to these animals, like bats have enriched pathways involving uterus development and squirrels changed DNA regions related to human pigmentation abnormalities"

 

After casting a wide net, Gregg and his team looked specifically at their finding related to elephant DNA repair. They found elephant-specific changes near a gene called FANCL, a master regulatory of DNA repair. Then, in collaboration with Joshua Schiffman, a pediatric oncologist at the Huntsman Cancer Institute and University of Utah, the group looked directly at elephant cells exposed to irradiation to identify a DNA damage response program in elephant cells. The researchers discovered that the entire set of DNA damage response genes is changed in the elephant--revealing a composite of candidate elements across the genome that can affect cancer.

 

"This was exactly what our hypothesis predicted," Gregg says. "The genes that were responding to DNA damage in elephant cells were enriched with elephant accelerated regions all around them, and what's exciting is those elements are conserved across mammals. They exist in humans, which means they may be relevant for shaping DNA damage responses in human cells."

 

Elephants need to be resistant to mutations because of the amount of cell division required to generate and sustain an organism of an elephant's size and lifespan. Humans are smaller and may have less evolutionary pressure to have similarly enhanced DNA repair mechanisms. Gregg argues that, by understanding the evolution of regulatory elements that contribute to enhanced cancer prevention in elephants, we may learn more about the mechanisms that can prevent cancer in humans.

 

Gregg's success with the elephant motivated his team to use other extraordinary species to further decode noncoding regions of the human genome. For example, bats evolved pointy ears and webbed fingers and toes, and Gregg's team discovered that the bat changed many noncoding regions near genes linked to Stahl ear, a human morphological disorder in which a person has "Spock-like" ears, and syndactyly, a condition in which a person's fingers are fused together. Naked mole rats, which live completely underground and have lost their vision, evolved changes around genes related to human glaucoma, a form of visual degeneration.

 

"What we have now is an atlas of new candidate elements for shaping particular phenotypes," Gregg says. "But this is just the beginning. We need functional studies to determine what the elements we discovered actually do, and whether they do have important functional roles in shaping clinically-relevant phenotypes."

 

Further reading: Animal Genome

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Physicists measured Earth’s mass using neutrinos for the first time

Physicists measured Earth’s mass using neutrinos for the first time | Amazing Science | Scoop.it
Counting tiny particles that can zip straight through the Earth reveals what the planet is like on the inside.

 

Puny particles have given scientists a glimpse inside the Earth.

For the first time, physicists have measured the planet’s mass using neutrinos, minuscule subatomic particles that can pass straight through the entire planet. Researchers also used the particles to probe the Earth’s innards, studying how the planet’s density varies from crust to core.

 

Typically, scientists determine Earth’s mass and density by quantifying the planet’s gravitational pull and by studying seismic waves that penetrate the globe. Neutrinos provide a completely independent test of the planet’s properties. Made using data from the IceCube neutrino observatory at the South Pole, the new planetary profile agreed with traditional measurements, a trio of physicists reports November 5, 2018 in Nature Physics.

 

To make the measurement, the scientists studied high-energy neutrinos that were produced when protons and other energetic particles from space slammed into the Earth’s atmosphere. These neutrinos can zip clean through the entire Earth, but sometimes they smash into atomic nuclei and are absorbed instead. How often neutrinos get stopped in their tracks reveals the density of the stuff they’re traveling through.

 

Neutrinos that arrived at the IceCube detector from different angles probed different layers of the Earth. For example, a neutrino coming from the opposite side of the planet, at the North Pole, would pass through the Earth’s crust, mantle and core before reaching the South Pole. But one that skimmed in at an angle might pass through only the crust. By measuring how many neutrinos came from various angles, the team inferred the densities of different parts of the Earth and its total mass.

 

The technique doesn’t yet reveal anything new about the planet. But one day it might help scientists determine whether all of Earth’s mass comes from normal matter. Perhaps some of the mass is due to something that shuns neutrinos, such as a type of dark matter, a shadowy substance that scientists believe must exist to account for missing mass observed in measurements of other galaxies. Neutrinos could help physicists nail down whether the Earth harbors such dark matter within.

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Yeast-E. coli hybrid shows how mitochondria might have evolved

Yeast-E. coli hybrid shows how mitochondria might have evolved | Amazing Science | Scoop.it

Yeast intentionally stuffed with bacteria may teach scientists something about the origins of cells’ powerhouses. Cellular power-generating organelles, called mitochondria, are thought to have once been bacteria captured by archaea, single-celled microbes that are one of the earliest forms of life. Now, almost all eukaryotic cells (cells with a nucleus) contain mitochondria.

 

At first, the bacteria may have lived inside archaea as endosymbionts, independent organisms that cooperate with their hosts. Over time, mitochondria lost many of their genes and eventually became an integral part of the cell. This scenario has support from genetics. But “if you really want to prove something’s true,” says chemical biologist Peter Schultz, researchers should be able to make something similar in the lab. So Schultz, of the Scripps Research Institute in La Jolla, Calif., and his colleagues created a hybrid cell by fusing two popular lab organisms — the baker’s yeast Saccharomyces cerevisiae and a common gut bacteria called E. coli.

 

“It’s a pioneering approach,” says evolutionary biologist Antonio Lazcano of the National Autonomous University of Mexico in Mexico City, who was not involved in the experiments. No one has made such a hybrid organism before. But the work, described October 29 in the Proceedings of the National Academy of Sciences, suggests it may not be so hard to make a free-living organism into an endosymbiont, he says.

 

Not that it was easy to get bacteria adapted to living on their own to grow inside another species’ cells. First, the researchers had to give the yeast and bacteria a reason to team up. Schultz’s team disabled a gene in yeast’s mitochondria so that the organelles couldn’t produce chemical energy in the form of adenosine triphosphate, or ATP, under some circumstances. E. coli were engineered to lack a gene needed to make the B vitamin thiamine, which the bacteria need to live. The team also outfitted the bacteria with a transporter protein that can move ATP and its precursor adenosine diphosphate, or ADP, in or out of the cell. When the bacteria was put inside the yeast cells, the bacteria supplied the ATP the yeast needed to live, and the yeast made thiamine for the bacteria.

 

It wasn’t a perfect arrangement, though. The yeast kept digesting the bacteria. So Schultz’s team equipped the E. coli with SNARE proteins from Chlamydia trachomatis bacteria, which can live inside human cells and cause the sexually transmitted disease chlamydia. SNARE proteins can prevent a host cell’s digestive compartments, called lysosomes, from coming together to dismantle invading microbes. SNARE-outfitted E. coli eventually were able to grow inside the yeast cell, the researchers found. The hybrid yeast-bacteria cells grew for more than 40 generations, the researchers report.

 

There’s no way to know the exact environmental and physiological conditions microbes faced that led to formation of eukaryotic cells 1.5 billion years ago, says evolutionary biologist Ryan Gawryluk of the University of Victoria in Canada who was not involved in the work. Exchanging energy for nutrients may have been one impetus for bacteria and archaea to join forces, but some scientists don’t think it was the evolutionary force that shaped the partnership, he says. After all, “bacteria have no interest in sending ATP outside of their cells.” Mitochondria-precursor bacteria may have been parasites or endosymbionts that gradually lost the ability to live outside the host for other reasons.

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Powerful method probes small-molecule structures

Powerful method probes small-molecule structures | Amazing Science | Scoop.it

Small molecules — from naturally occurring metabolites and hormones to synthetic medicines and pesticides — can have big effects on living things. But for scientists to understand how the molecules work and how to design beneficial ones, they need to know the precise arrangement of atoms and chemical bonds. Now researchers have found a faster, simpler and potentially more reliable way to solve the structures of small molecules. They report their results in ACS Central Science.

 

Currently, the gold standard for determining small-molecule structures is X-ray crystallography. In this technique, researchers crystallize a small molecule and then bombard the crystal with X-rays, which diffract in complex patterns that reveal the molecule’s 3D structure. However, producing large, high-quality crystals is time-consuming or impossible for many compounds. Brian Stoltz, Jose Rodriguez, Hosea Nelson and Tamir Gonen wondered if they could use a form of cryoelectron microscopy to characterize small molecules. Known as microcrystal-electron diffraction (MicroED), this technique was developed 5 years ago to study protein structures. In this technique, electron beams, instead of X-rays, are diffracted from crystals, which can be much smaller than those required for X-ray crystallography.

 

The researchers first tested MicroED on a sample of powdered progesterone, which contained thousands of nanocrystals. They rotated a single crystal and collected electron diffraction data from different angles, determining the structure of the hormone at high resolution (1 angstrom) in less than 30 minutes, compared with weeks or months for X-ray crystallography. They went on to successfully characterize 11 other natural, synthetic and pharmaceutical products, including acetaminophen, ibuprofen and several antibiotics. The researchers even identified four different molecules in a mixture by studying individual nanocrystals.

 

Using MicroED, the researchers analyzed crystals that were a billionth of the size typically needed for X-ray crystallography. The rapid, precise method has the potential to greatly accelerate research in the fields of synthetic chemistry, natural product chemistry and drug discovery, the researchers say.

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Feeding a population of 9 billion in 2050 will require much more food than previously calculated

Feeding a population of 9 billion in 2050 will require much more food than previously calculated | Amazing Science | Scoop.it
Food demand is growing as people get bigger. Feeding a population of 9 billion in 2050 will require much more food than previously calculated.

 

“It will be harder to feed 9 billion people in 2050 than it would be today,” says Gibran Vita, a PhD candidate at NTNU ‘s Industrial Ecology Program. According to WWF, the world’s greatest environmental problem is the destruction of wildlife and plant habitat. A large part of the devastation is due to the demands of an ever-increasing human population. On the other hand, “Zero Hunger” is the second UN Sustainable Development Goal and its challenge is to meet a global growing food demand.

 

The same food doesn’t cut it anymore. Changes in eating habits, attitudes towards food waste, and social and medical conditions have changed the situation. The number of people could level off at around nine billion in a few years, compared to just over 7.6 billion now.

 

But an average person in the future will require more food than today. Changes in eating habits, attitudes towards food waste, increases in height and body mass, and demographic transitions are some of the reasons.

 

Professor Daniel B. Müller and colleagues Felipe Vásquez and Vita analyzed changes in the populations of 186 countries between 1975 and 2014. “We studied the effects of two phenomena. One is that people on average have become taller and heavier. The second is that the average population is getting older,” said Vita. The first phenomenon contributes to increased food demand. The second counteracts the former one.

 

An average adult in 2014 was 14 per cent heavier, about 1.3 per cent taller, 6.2 per cent older, and needed 6.1 per cent more energy than in 1975. Researchers expect this trend to continue for most countries. “An average global adult consumed 2465 kilocalories per day in 1975. In 2014, the average adult consumed 2615 kilocalories,” says Vita.

 

Globally, human consumption increased by 129 per cent during this time span. Population growth was responsible for 116 per cent, while increased weight and height accounted for 15 per cent. Older people need a little less food, but an aging population results in only two per cent less consumption. “The additional 13 per cent corresponds to the needs of 286 million people,” Vásquez says. This in turn corresponds approximately to the food needs of Indonesia and Scandinavia combined.

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Uranium-based complex that allows nitrogen fixation reactions to take place in ambient conditions

Uranium-based complex that allows nitrogen fixation reactions to take place in ambient conditions | Amazing Science | Scoop.it

EPFL scientists have developed an uranium-based complex that allows nitrogen fixation reactions to take place in ambient conditions. The work lays the foundation to develop new processes for synthesizing nitrogen products like cyanamide.

Abundant in nature (78% of the air we breathe), nitrogen is rarely used in the industrial production of chemicals, with the most important process being the synthesis of ammonia, which is in turn used for the preparation of agricultural fertilizers.

 

Using nitrogen as a raw material (“feedstock”) for industrial usage is accomplished by a reaction known as “nitrogen fixation”. In this reaction, molecular nitrogen (or “dinitrogen”; N2) is split into two atoms of nitrogen that can then be connected to other elements like hydrogen or carbon, which allow nitrogen to be stored as ammonia or converted directly in higher value compounds.

 

But ammonia is not easy to make on an industrial level; the main process, called “Haber-Bosch”, uses an iron-based catalyst at temperatures around 450oC and pressures of 300 bar — almost 300 times the pressure at sea level. In order to make the process more cost-effective, chemists have focused on the development of new systems that can transform nitrogen into useful compounds using mild low-energy conditions.

 

In 2017, the lab of Marinella Mazzanti at EPFL was able to convert molecular nitrogen into ammonia in ambient conditions by synthesizing a compound containing two uranium(III) ions and three potassium centers held together by a nitride group.

Now, the group, in collaboration with other EPFL groups, has shown that by replacing the nitride bridge in the uranium system with an oxo bridge they can still bind dinitrogen. In addition, the bound dinitrogen can be easily cleaved in ambient conditions by carbon monoxide to make cyanamide, a compound that is widely used in agriculture, pharmaceuticals, and various organic compounds.

 

The reactivity of the oxo-bridged dinitrogen complex was remarkably different compared to the previous nitride complex and the few other nitrogen complexes known in the field. Computational studies then allowed the scientists to relate these differences in reactivity to the bonding in the uranium-oxo/-nitride bridge.

 

“These findings provide important insight into the relation between structure and reactivity that should extend to nitride and oxide materials,” says Marinella Mazzanti. “Moreover, the implementation of these compounds in catalytic systems could ultimately lead to a lower cost access to fertilizers.”

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'Bionic mushrooms' fuse nanotech, bacteria and fungi

'Bionic mushrooms' fuse nanotech, bacteria and fungi | Amazing Science | Scoop.it

In their latest feat of engineering, researchers at Stevens Institute of Technology have taken an ordinary white button mushroom from a grocery store and made it bionic, supercharging it with 3D-printed clusters of cyanobacteria that generate electricity and swirls of graphene nanoribbons that can collect the current.

 

The work, reported in the Nov. 7, 2018 issue of Nano Letters, may sound like something straight out of Alice in Wonderland, but the hybrids are part of a broader effort to better improve our understanding of cells biological machinery and how to use those intricate molecular gears and levers to fabricate new technologies and useful systems for defense, healthcare and the environment.

 

"In this case, our system -- this bionic mushroom -- produces electricity," said Manu Mannoor, an assistant professor of mechanical engineering at Stevens. "By integrating cyanobacteria that can produce electricity, with nanoscale materials capable of collecting the current, we were able to better access the unique properties of both, augment them, and create an entirely new functional bionic system."

 

Cyanobacteria's ability to produce electricity is well known in bioengineering circles. However, researchers have been limited in using these microbes in bioengineered systems because cyanobacteria do not survive long on artificial bio-compatible surfaces. Mannoor and Sudeep Joshi, a postdoctoral fellow in his lab, wondered if white button mushrooms, which naturally host a rich microbiota but not cyanobacteria specifically, could provide the right environment -- nutrients, moisture, pH and temperature -- for the cyanobacteria to produce electricity for a longer period.

 

Mannoor and Joshi showed that the cyanobacterial cells lasted several days longer when placed on the cap of a white button mushroom versus a silicone and dead mushroom as suitable controls. "The mushrooms essentially serve as a suitable environmental substrate with advanced functionality of nourishing the energy producing cyanobacteria," says Joshi. "We showed for the first time that a hybrid system can incorporate an artificial collaboration, or engineered symbiosis, between two different microbiological kingdoms."

 

Mannoor and Joshi used a robotic arm-based 3D printer to first print an "electronic ink" containing the graphene nanoribbons. This printed branched network serves as an electricity-collecting network atop the mushroom's cap by acting like a nano-probe -- to access bio-electrons generated inside the cyanobacterial cells. Imagine needles sticking into a single cell to access electrical signals inside it, explains Mannoor.

 

Next, they printed a" bio-ink" containing cyanobacteria onto the mushroom's cap in a spiral pattern intersecting with the electronic ink at multiple contact points. At these locations, electrons could transfer through the outer membranes of the cyanobacteria to the conductive network of graphene nanoribbons. Shining a light on the mushrooms activated cyanobacterial photosynthesis, generating a photocurrent.

 

In addition to the cyanobacteria living longer in a state of engineered symbiosis, Mannoor and Joshi showed that the amount of electricity these bacteria produce can vary depending on the density and alignment with which they are packed, such that the more densely packed together they are, the more electricity they produce. With 3D printing, it was possible to assemble them so as to boost their electricity-producing activity eight-fold more than the casted cyanobacteria using a laboratory pipette.

 

Recently, a few researchers have 3D printed bacterial cells in different spatial geometrical patterns, but Mannoor and Joshi, as well as co-author Ellexis Cook, are not only the first to pattern it to augment their electricity-generating behavior but also integrate it to develop a functional bionic architecture.

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One-third of known exoplanets may be enormous ocean worlds, good news for alien exo-life search

One-third of known exoplanets may be enormous ocean worlds, good news for alien exo-life search | Amazing Science | Scoop.it

Water is a key ingredient for life — and new research suggests we might find it all over the galaxy.

Scientists looked at the mass of super-Earths, a kind of planet common across the cosmos but not present in our own solar system. These rocky worlds are several times larger than Earth, but the team’s analysis of known super-Earths reveals something astounding: Many of them may be literal water worlds.

According to new research, many of these exoplanets may be half water. By comparison, water is just a tiny fraction of Earth’s mass. But that doesn’t automatically mean that these super-Earths are friendly places to any form of life. The Harvard-led team determined that those planets with 1.5 times Earth’s radius or below would be terrestrial, or rocky.

Super-Earths above 2.5 Earth radius might be more like tiny versions of Neptune or Uranus. The two water-dominated planets in our solar system are far from life friendly. Such hulking super-Earths would be enshrouded by a mostly-water vapor atmosphere. Further below, there might be oceans at extreme pressures and temperatures — between 390 and 930 degrees Fahrenheit (200 to 500 Celsius). But that doesn’t necessarily preclude life.

“Life could develop in certain near-surface layers on these water worlds when the pressure, temperature and chemical conditions are appropriate,” says the study’s lead author, Li Zeng of Harvard University. Zeng also believes that these planets may form more like a gas giant, with a core deep underneath a dense atmosphere.

“One has to realize that, although water appears to be precious and rarer on Earth and other inner solar system terrestrial planets, it is in fact one of the most abundant substance in the universe, since oxygen is the third most abundant element after hydrogen and helium,” Zeng said.

And based on the team’s modeling, up to 35 percent of known planets might be water worlds. That could mean the coming years will lead to the discovery of a whole lot of exo-oceans — and a whole host of new questions.

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Scientists vote on first change to kilogram in a century

Scientists vote on first change to kilogram in a century | Amazing Science | Scoop.it

The weight is defined by a lump of metal in a Paris vault - which could make Earth ‘laughing stock of universe’.

 

For the band of specialists in the much-overlooked arena of metrology, it will be the most profound moment in more than a century. Since 1889, one of the pillars of the science, the kilogram, has been defined by a lump of metal held in a triple-locked vault in a lab on the outskirts of Paris. It is the one true kilogram in the world.

 

But not for much longer. Next week, leading figures in the field are set to make history. At the general conference on weights and measures in Versailles, representatives from 57 nations will vote for change. And so the kilogram, the only metric unit still based on a solitary object, will be reborn. Henceforth, the kilogram will be derived from a fundamental constant, a number that is woven into the fabric of the universe.

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Machine learning spots natural selection at work in human genome

Machine learning spots natural selection at work in human genome | Amazing Science | Scoop.it

Pinpointing where and how the human genome is evolving can be like hunting for a needle in a haystack. Each person’s genome contains three billion building blocks called nucleotides, and researchers must compile data from thousands of people to discover patterns that signal how genes have been shaped by evolutionary pressures.

 

To find these patterns, a growing number of geneticists are turning to a form of machine learning called deep learning. Proponents of the approach say that deep-learning algorithms incorporate fewer explicit assumptions about what the genetic signatures of natural selection should look like than do conventional statistical methods.

 

“Machine learning is automating the ability to make evolutionary inferences,” says Andrew Kern, a population geneticist at the University of Oregon in Eugene. “There is no question that it is moving things forward.”

 

One deep-learning tool called ‘DeepSweep’, developed by researchers at the Broad Institute of MIT and Harvard in Cambridge, Massachusetts, has flagged 20,000 single nucleotides for further study. Some or all of these simple mutations may have helped humans survive disease, drought or what Charles Darwin called the “conditions of life”, researchers reported last month at the annual meeting of the American Society of Human Genetics in San Diego, California.

 

Since the 1970s, geneticists have created mathematical models to describe the fingerprint of natural selection in DNA. If a mutation arises that renders a person better able to survive and produce offspring than their neighbours, the percentage of the population with that gene variant will grow over time.

 

One example is the mutation that gives many adults the ability to drink cow’s milk. It enables the body to produce lactase, an enzyme that digests the sugar in milk, into adulthood. By analysing human genomes with statistical methods, researchers discovered that the mutation spread rapidly through communities in Europe thousands of years ago— presumably because nutrients in cow’s milk helped people to produce healthy children1,2 . Today, nearly 80% of people of European descent carry this variant.

 

Yet geneticists have struggled to identify, and confirm, other specific snippets of the genome that spread throughout populations because they provided an adaptive edge. Deep learning excels at just this sort of task: discovering subtle patterns hidden in large amounts of data. But there is a catch. Deep-learning algorithms often learn to classify information after being trained by exposure to real data; Facebook, for example, primes algorithms to recognize faces on the basis of pictures that people have already labelled. Because geneticists don’t yet know which parts of the genome are being shaped by natural selection, they must train their deep-learning algorithms on simulated data.

 

Generating that simulated data requires researchers to posit what the signature of natural selection looks like, says Sohini Ramachandran, a population geneticist at Brown University in Providence, Rhode Island. “We don’t have ground truth data, so the worry is that we may not be simulating properly.” And because deep-learning algorithms operate as black boxes, it’s hard to know what criteria they use to identify patterns in data, says Philipp Messer, a population geneticist at Cornell University in Ithaca, New York. “If the simulation is wrong, it’s not clear what the response means,” he adds.

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Thanatin from the spined soldier bug is a new type of antibiotic against gram-negative bacteria

Thanatin from the spined soldier bug is a new type of antibiotic against gram-negative bacteria | Amazing Science | Scoop.it

With the increasing resistance of many Gram-negative bacteria to existing classes of antibiotics, identifying new paradigms in antimicrobial discovery is an important research priority. Of special interest are the proteins required for the biogenesis of the asymmetric Gram-negative bacterial outer membrane (OM)

 

Seven Lpt proteins (LptA to LptG) associate in most Gram-negative bacteria to form a macromolecular complex spanning the entire envelope, which transports lipopolysaccharide (LPS) molecules from their site of assembly at the inner membrane to the cell surface, powered by adenosine 5′-triphosphate hydrolysis in the cytoplasm. The periplasmic protein LptA comprises the protein bridge across the periplasm, which connects LptB2FGC at the inner membrane to LptD/E anchored in the OM.

 

Scientists now show that the naturally occurring, insect-derived antimicrobial peptide thanatin targets LptA and LptD in the network of periplasmic protein-protein interactions required to assemble the Lpt complex, leading to the inhibition of LPS transport and OM biogenesis in Escherichia coli.

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Resiniferatoxin (RTX) Is So Hot It Destroys Nerve Fiber Endings

Resiniferatoxin (RTX) Is So Hot It Destroys Nerve Fiber Endings | Amazing Science | Scoop.it

In Morocco there grows a cactus-like plant, that contains a chemical that is so hot that it destroys nerve endings on contact. On the Scoville Scale of hotness, its active ingredient, resiniferatoxin (RTX), clocks in at 16 billion units. That’s 10,000 times hotter than the Carolina reaper, the world’s hottest pepper, and 45,000 times hotter than the hottest of habaneros, and 4.5 million times hotter than a piddling little jalapeno. Euphorbia resinifera, aka the resin spurge, is not to be eaten. Just to be safe, you probably shouldn’t even look at it.

 

But while that toxicity will lay up any mammal dumb enough to chew on the resin spurge, resiniferatoxin has also emerged as a promising painkiller. Inject RTX into an aching joint, and it’ll actually destroy the nerve endings that signal pain. Which means medicine could soon get a new tool to help free us from the grasp of opioids.

 

The human body is loaded with different kinds of sensory neurons. Some flavors respond to light touch, others signal joint position, yet others respond only to stimuli like tissue injury and burns. RTX isn’t going to destroy the endings of all these neurons unbiased. Instead, it binds to a major molecule in specifically pain-sensing nerve endings, called TRPV1.

 

This TRPV1 receptor normally responds to temperature. But it also responds to a family of molecules called pungents, which includes capsaicin, the active ingredient in hot pepper. “So when you put hot pepper on your tongue and it feels like it's burning, it's not because your tongue is on fire,” says Tony Yaksh, an anesthesiologist and pharmacologist at UC San Diego who’s studied RTX. “It's simply activating the same sensory axons that would have been activated if your tongue had been on fire.”

 

RTX is a capsaicin analog, only it’s between 500 and 1,000 times more potent. When RTX binds to TRPV1, it props open the nerve cell’s ion channel, letting a whole lot of more calcium in than it normally does. That’s toxic, leading to the inactivation of the pain-sensing nerve endings.

 

Other varieties of sensory neurons are left unaffected, because RTX is highly specific to TRPV1. “So you gain selectivity because it only acts on TRPV1, which is only on a certain class of fibers, which only transmit pain,” says Yaksh. “Therefore you can selectively knock out pain without knocking out, say, light touch or your ability to walk.”

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The Hoyle State: A Primordial Nucleus behind the Elements of Life

The Hoyle State: A Primordial Nucleus behind the Elements of Life | Amazing Science | Scoop.it

Using supercomputers and new mathematical techniques, physicists are working to reveal how the Hoyle state atomic nucleus gives rise to the light elements that enable life, and how it drives the evolution of stars.

 

Carbon, so crucial for the chemistry of all living organisms and life in general, forms at the interior of burning stars in what is called the triple-alpha process: two alpha particles (helium nuclei) react to form beryllium- 8, which in turn reacts with a third alpha particle to form carbon- 12. This last step does not produce the carbon- 12 as we know it, however, but rather an excited state called the Hoyle state.

 

This state is a resonance, meaning it is not localized spatially and it has a finite lifetime governed by its distance (in energy) from the particle-emission threshold. The resonance allows approximately four out of ten thousand decays to produce the ground state of carbon- 12. Fred Hoyle predicted the resonance in 1954, arguing that without it, stable carbon would not exist [1]. Three years later, an experimental group at Caltech proved he was right [2].

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Web resource: 1000 Fungal Genomes Project

Web resource: 1000 Fungal Genomes Project | Amazing Science | Scoop.it

Sequencing unsampled fungal diversity.  Efforts to sequence 1000+ fungal genomes. Also see the Google+ site for more discussion opportunities.

 

This project is in collaboration with the work of the JGI and you can find links on this site to the nomination page for submitting candidate species to the project.

 

The project is continuing to sequence genomes at a fast pace due to the efforts of the DOE JGI’s work and collaborating labs preparing DNA and RNA. The number of genomes in the Mycocosm system is now more than 1000 and the 1KFG project has contributed many hundred to this effort. There are working phylogenetic and comparative genomic papers to describe more of what can be learned from these data about the evolution and biology of fungi.


Via Kamoun Lab @ TSL, Dr. Stefan Gruenwald
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Electrons go fractal: Physicists wrangled electrons into a quantum fractal

Electrons go fractal: Physicists wrangled electrons into a quantum fractal | Amazing Science | Scoop.it
The tiny, repeating structure could reveal weird behavior of electrons in fractional dimensions.

 

Physicists have created an oddity known as a quantum fractal, a structure that could reveal new and strange types of electron behaviors. Fractals are patterns that repeat themselves on different length scales:  Zoom in and the structure looks the same as it does from afar. They’re common in the natural world. For instance, a cauliflower stalk looks like a miniature version of the full head. A lightning stroke splits into many branches, each of which has the same forked structure as the whole bolt.

 

But in the tiny quantum realm, fractals aren’t so easy to come by. Now scientists have artificially created a quantum fractal by placing carbon monoxide molecules on a copper surface. Confined between the molecules, electrons in the copper form a fractal shape of triangles within triangles called a Sierpinski triangle (SN Online: 12/30/02), the researchers report November 12 in Nature Physics. A full-fledged Sierpinski triangle would contain an infinite number of triangles, so the researchers created an approximation to that shape, with enough triangles for its repeating structure to be evident.

 

Electrons inhabiting a fractal don’t live in 3-D like the rest of us. Nor do they exist in a flat 2-D world or a one-dimensional line. Instead they occupy an in-between, fractional number of dimensions. In this case, the scientists found that the electrons lived in approximately the number of dimensions expected for a Sierpinski triangle, 1.58 to be precise.

 

Quantum particles tend to act in unusual ways when confined to one or two dimensions. Scientists don’t yet know how electrons will behave in fractional dimensions, says physicist Cristiane Morais Smith of Utrecht University in the Netherlands. “What can come out of our work is completely uncharted territory.”

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New Air-Conditioner Absorbs Solar Energy and Blasts Radiation Into Space

New Air-Conditioner Absorbs Solar Energy and Blasts Radiation Into Space | Amazing Science | Scoop.it

Scientists are using solar energy and outer space to make a fossil fuel-free air conditioner. This new, developing device works to both heat and cool the area around it without fossil fuels.

 

As people search for solutions to the climate change crisis on Earth, scientists are working to create renewable energy sources as alternatives to fossil fuels. Now, scientists at Stanford University hope to offer a new solution as they are developing a single device that collects solar energy and shoots radiation out into space – acting as both a heater and air conditioner.

Collecting the sun’s energy via solar power has been a leading alternative energy source for many years. But this new work suggests that devices could both collect solar energy could and also use what is described as “space energy,” which isn’t really a source of energy, but rather a heat sink.

Alternative Cooling

Objects emit heat as infrared radiation (a type of light we can’t see). This radiation is mostly reflected back to Earth by reflective particles in the atmosphere. But some of it can escape into space. But this new technology, known as “radiative cooling,” capitalizes on this process and uses infrared light to cool its surrounding area, essentially allowing for fossil fuel-free air conditioning.

Space Energy

The research team thinks that such cooling “space energy” could potentially improve the efficiency of solar cells. And they’ve now developed a device that combines radiative cooling and solar absorption tech. “On a rooftop, we imagine a photovoltaic cell can supply electricity while the radiative cooler can cool down the house on hot summer days,” study lead author Zhen Chen, who is a former postdoctoral research associate at Stanford University and current professor at the Southeast University of China, said in a statement.

 

The device is made up of a solar absorber on top of a radiative cooler, which is composed of layers of nitride, silicon and aluminum. These layers are then vacuum-sealed to prevent heat loss. The device takes in solar energy and reflects infrared radiation in the cooler back to outer space. The device is still in development, but the researchers behind it claim that it can warm the surrounding area up to 75 degrees Fahrenheit (24 degrees Celsius) and cool the surrounding area up to 84 degrees Fahrenheit (29 degrees Celsius). The team also asserts that, since the solar absorber blocks the radiative cooler, it improves its performance.

 

But, while the promise of cooling your home using reflected infrared radiation from outer space sounds intriguing, it’s far from ready. Chen said there is a lot of work left to do before this technology could be scaled up and capable of commercial use.

If it works, the tech could be significant. The International Energy Agency says that emissions from air conditioners will continue to increase dramatically in the years ahead. As our planet warms, more people will use air conditioners and contribute to increased fossil fuel use.

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How Dad's Stress Gets Passed Down to Offspring

How Dad's Stress Gets Passed Down to Offspring | Amazing Science | Scoop.it

A stressed-out and traumatized father can leave scars in his children. New research suggests this happens because sperm “learn” paternal experiences via a mysterious mode of intercellular communication in which small blebs break off one cell and fuse with another.

 

Carrying proteins, lipids and nucleic acids, these particles ejected from a cell act like a postal system that extends to all parts of the body, releasing little packages known as extracellular vesicles. Their contents seem carefully chosen. “The cargo inside the vesicle determines not just where it came from but where it’s going and what it’s doing when it gets there,” says Tracy Bale, a neurobiologist at the University of Maryland School of Medicine.

 

Preliminary research Bale and others, announced this week at the annual meeting of the Society for Neuroscience in San Diego, shows how extracellular vesicles can regulate brain circuits and help diagnose neurodegenerative diseases—in addition to altering sperm to disrupt the brain health of resulting offspring. Striking evidence that harsh conditions affect a man’s children came from crop failures and war ravaging Europe more than a century ago. In those unplanned human experiments, prolonged famine appeared to set off a host of health changes in future generations, including higher cholesterol levels and increased rates of obesity and diabetes. To probe the inheritance of such changes at the cellular level, Bale and co-workers performed a series of mouse experiments.

 

It is pretty easy to stress out a mouse. Stick one into a tube it cannot wriggle out of, soak its bedding or blast white noise—and stress hormone levels shoot up, much as they do in people worrying about finances or facing incessant pressure at work. Remarkably, the way a mouse physiologically responds to stress looks noticeably different if—months before conception—its father endured a period of stress. Somehow “their brain develops differently than if their dad hadn’t experienced that stress,” says Chris Morgan, a postdoc in Bale’s lab who helped create the mouse model.

 

The big question is how information about the paternal environment reaches the womb in the first place. After all, Morgan says, the “dad is only in there for one night, perhaps just a few hours.” Could his sperm carry memories of prior trauma? The idea seemed reasonable yet controversial. Because DNA is packed so tightly in the nucleus of a sperm cell, “the thought that [the cell] would respond to anything in the environment really boggled people’s minds,” says Jennifer Chan, a former PhD student in Bale’s lab who’s now a postdoc at Icahn School of Medicine at Mount Sinai in New York City.

 

Rather, there must be some other kind of cell whose DNA does react to environmental changes—and that cell, she reasoned, could then relay that information to sperm cells to transmit at fertilization. She focused on a population of cells that interact with developing sperm by releasing molecules that help sperm grow and mature. They also secrete extracellular vesicles—and Chan showed it is these vesicles whose contents fuse with sperm cells, instilling memories of dad’s prior stress.

 

In one set of experiments Chan stressed a group of male mice, let them mate and looked at stress responses in the pups. The clincher was a set of in vitro fertilization–like experiments in which she collected sperm from a male mouse that had never experienced induced stress. Half his sperm went into a lab dish with vesicles previously exposed to stress hormones. The other half was cultured with vesicles that had no contact with stress hormones.

 

Chan injected sperm cells from each batch into eggs from a non-stressed female, then implanted the fertilized eggs—zygotes—into the same foster mom. The pups from non-stressed zygotes developed normally. Pups from stress-exposed zygotes, however, showed the same abnormal stress response as those whose dads had experienced stress before mating. That showed extracellular vesicles act as the conduit for transmitting paternal stress signals to the offspring, Chan says.

 

The findings are “novel and of very high impact, especially when we consider the impact of military service or other work environments that can confer high stress,” says Robert Rissman, a neuroscientist at the University of California, San Diego, who was not involved with the research. “I think it would be important to better understand the specificity of the effect and how different types of stressors or strength of stressors can modulate this system.”

 

As a first step toward translating the findings to people, Morgan is collaborating with University of Pennsylvania psychiatrist Neill Epperson to track protein and RNA changes in human sperm samples. At the neuroscience meeting, Morgan presented data from a six-month study of 20 undergraduate and graduate students. Each month the participants came in and gave a sperm donation. They also completed a same-day survey asking how stressed they were feeling. Preliminary data suggests just several months after a student reports stress, his sperm shows changes in “small noncoding RNAs”—RNA molecules that do not get translated to protein but instead control which genes get turned on or off.

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Synthetic molecule invades double-stranded DNA and RNA under normal physiological conditions

Synthetic molecule invades double-stranded DNA and RNA under normal physiological conditions | Amazing Science | Scoop.it

Carnegie Mellon University researchers have developed a synthetic molecule that can recognize and bind to double-stranded DNA or RNA under normal physiological conditions. The molecule could provide a new platform for developing methods for the diagnosis and treatment of genetic conditions. Their findings are published in Communications Chemistry, a new Nature journal.

 

The work was carried out by an international team of experts, including Carnegie Mellon Professor of Chemistry Danith Ly, an expert in peptide nucleic acid design, chemistry postdoc Shivaji Thadke and chemistry graduate student Dinithi Perera, Chemistry Professor and nuclear magnetic resonance expert Roberto Gil, and Arnab Mukherjee, a computer scientist at The Indian Institute of Science Education and Research at Pune.

 

"Since the double-helical structure of DNA was first elucidated by Watson and Crick, scientists have been trying to design molecules that can bind to DNA and allow one to control the flow of genetic information," said Ly. "This is the first bifacial molecule that can invade double-stranded DNA or RNA under biologically relevant conditions."

 

DNA, which contains all of an organism's genetic information, is made up of two strands of nucleotides. The nucleotides connect with each other using hydrogen bonds, forming a helical chain of Watson-Crick base pairs. While these base pairs provide a relatively simple code to our genetic information, getting into the double helix to change the code is difficult due to the strong bonds between the base-pairs.

 

Ly and his colleagues at Carnegie Mellon University's Institute for Biomolecular Design and Discovery (IBD) and Center for Nucleic Acids Science and Technology (CNAST) are leaders in the design and development of gamma peptide nucleic acids (gamma PNAs). Synthetic analogs to DNA and RNA, gamma PNAs can be programmed to bind to the genetic material (DNA or RNA) that causes disease, allowing them to search for detrimental sequences and bind to them to prevent a gene from malfunctioning.

 

The group has created double-faced gamma PNAs called Janus gamma PNAs. Named after the two-faced Roman god, Janus PNAs are able to recognize and bind with both strands of a DNA or RNA molecule.

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Global warming has never stopped in the past hundred years

Global warming has never stopped in the past hundred years | Amazing Science | Scoop.it

Global warming has been attributed to persistent increases in atmospheric greenhouse gasses (GHGs), especially in CO2, since 1870, the beginning of the Industrial Revolution. Nevertheless, the upward trend in global mean surface temperature (GMST) slowed or even paused during the first decade of the twenty-first century, even though CO2 levels continued to rise and reached nearly 400 ppm in 2013. This episode has typically been termed the global warming hiatus or slowdown in warming. The hiatus is characterized as a near-zero trend over a period. Detection found that the hiatus appeared during 2001-2013/2002-2012 with extremely weak interannual variability in some GMST sequences, and the slowdown in the others.

 

The hiatus is often attributed to internal climate variability, external forcing, or both, involving an increase in aerosols in the stratosphere during the period 2000-2010, the negative phase of the Interdecadal Pacific Oscillation (IPO) accompanying intensified trade winds, extensive heat uptake by the deep ocean or an extremely low number of sunspots during the latest solar activity cycle.

 

A new study published in hScientific Reports reveals that the global warming has never stopped in the past hundred years, with maximum rate of change after Second World War II and almost constant rate (0.08oC/10a) during the latest three decades. However, the key cooling against global warming comes from the interannual variability of the temperature that is coincided with the variability of the sea surface temperature in the equatorial mid-eastern Pacific. Hence, the hiatus is merely a decadal balance between global warming and the cooling resulting from anomalous sea surface temperature in equatorial Pacific.

 

The hiatus ended in 2014 as a new El Niño Southern Oscillation (ENSO) event was developing in the equatorial mid-eastern Pacific which caused a rapid warming in the earth. On the other hand, the multidecadal climate oscillation follows a downward path with increase in cooling.

 

"Our study suggests that future climate conditions will likely rely on competition between multidecadal cooling and global warming if the multidecadal climate cycle repeats, as was experienced during the second half of the twentieth century." Says Dr. Xingang Dai, the lead author from Institute of Atmospheric Physics at Chinese Academy of Sciences.

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Rare Blue Asteroid Reveals Itself During Fly-By

Rare Blue Asteroid Reveals Itself During Fly-By | Amazing Science | Scoop.it

Blue asteroids are rare, and blue comets are almost unheard of. An international team led by Teddy Kareta, a doctoral student at the University of Arizona's Lunar and Planetary Laboratory, investigated Phaethon, a bizarre asteroid that sometimes behaves like a comet, and found it even more enigmatic than previously thought.

 

Kareta presented the results during a press conference on Oct. 23 at the 50th annual meeting of the American Astronomical Society's Division for Planetary Science in Knoxville, Tennessee. Using telescopes in Hawaii and Arizona, the team studied sunlight reflected off Phaethon, which is known to be blue in color. Blue asteroids, which reflect more light in the blue part of the spectrum, make up only a fraction of all known asteroids. A majority of asteroids are dull grey to red, depending on the type of material on their surface.

 

Phaethon sets itself apart for two reasons: it appears to be one of the "bluest" of similarly colored asteroids or comets in the solar system; and its orbit takes it so close to the sun that its surface heats up to about 800 degrees Celsius (1,500 degrees Fahrenheit), hot enough to melt aluminum. Astronomers have been intrigued by Phaethon for other reasons, too. It has the qualities of both an asteroid and a comet based on its appearance and behavior.

 

Phaethon always appears as a dot in the sky, like thousands of other asteroids, and not as a fuzzy blob with a tail, like a comet. But Phaethon is the source of the annual Geminid meteor shower, easily seen in early-to-mid December.

 

Meteor showers occur when Earth passes through the trail of dust left behind on a comet's orbit. When they occur and where they appear to originate from depends on how the comet's orbit is oriented with respect to the Earth. Phaethon is thought to be the "parent body" of the Geminid meteor shower because its orbit is very similar to the orbit of the Geminid meteors.

 

Until Phaeton was discovered in 1983, scientists linked all known meteor showers to active comets and not asteroids. "At the time, the assumption was that Phaethon probably was a dead, burnt-out comet," Kareta said, "but comets are typically red in color, and not blue. So, even though Phaeton's highly eccentric orbit should scream 'dead comet,' it's hard to say whether Phaethon is more like an asteroid or more like a dead comet."

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The Cultural Brain Hypothesis: How culture drives brain expansion, sociality, and history

The Cultural Brain Hypothesis: How culture drives brain expansion, sociality, and history | Amazing Science | Scoop.it

In the last few million years, the cranial capacity of the human lineage dramatically increased, more than tripling in size [13]. This rapid expansion of the human brain size may be part of a gradual and longer-term trend toward larger, more complex brains in many taxa [37]. These patterns of increasing brain size are puzzling since brain tissue is energetically expensive [813].

 

Efforts to understand the evolutionary forces driving brain expansion have focused on climatic, ecological, and social factors [131415]. Scientists now provide an integrated model that attempts to explain both the broader patterns across taxa and the human outlier. To do this, they develop an analytic model and agent-based simulation based on the Cultural Brain Hypothesis (CBH): the idea that brains have been selected for their ability to store and manage information via some combination of individual (asocial) or social learning [1621]. The researchers develop the idea that bigger brains have evolved for more learning and better learning. The information acquired through these various learning processes is locally adaptive, on average, and could be related to a wide range of behavioral domains, which could vary from species to species. The forms of learning they model could plausibly apply to problems such as finding resources, avoiding predators, locating water, processing food, making tools, and learning skills, as well as to more social strategies related to deception, coercion, manipulation, coordination or cooperation. Their results suggest that the same underlying selective process that led to widespread social learning [22] may also explain the correlations observed across species in variables related to brain size, group size, social learning, innovation, and life history. Moreover, the parameters in the formal representation of our theory offer hypotheses for why brains have expanded more in some lineages than others [4423].

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Amazon rainforest can't keep up with climate change

Amazon rainforest can't keep up with climate change | Amazing Science | Scoop.it

A team of more than 100 scientists has assessed global warming's impact on thousands of tree species across the Amazon rainforest, assessing the winners and losers from 30 years of climate change.

 

Their analysis found that the effects of climate change are altering the rainforest’s composition of tree species, but not quickly enough to keep up with the changing environment. The team, led by University of Leeds in collaboration with more than 30 institutions around the world, used long-term records from more than a hundred plots as part of the Amazon Forest Inventory Network (RAINFOR) to track the lives of individual trees across the Amazon region.

 

Their results found that since the 1980s, the effects of global environmental change – stronger droughts, increased temperatures and higher levels of carbon dioxide in the atmosphere – has slowly affected specific tree species’ growth and mortality.

 

In particular, the study found that the most moisture-loving tree species are dying more frequently than other species and those suited to drier climates are unable to replace them.

 

Lead author Dr Adriane Esquivel Muelbert, from the School of Geography at Leeds, said: "The ecosystem’s response is lagging behind the rate of climate change. "The data showed us that the droughts that hit the Amazon basin in the last decades had serious consequences for the make-up of the forest, with higher mortality in tree species most vulnerable to droughts and not enough compensatory growth in species better equipped to survive drier conditions."

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