How conversion of forests to cropland affects climate

Date:

September 8, 2014

Source:

Yale School of Forestry & Environmental Studies

Summary:

The conversion of forests into cropland worldwide has triggered an atmospheric change to emissions of biogenic volatile organic compounds that -- while seldom considered in climate models -- has had a net cooling effect on global temperatures, according to a new study.

The conversion of forests into cropland worldwide has triggered an atmospheric change that, while seldom considered in climate models, has had a net cooling effect on global temperatures, according to a new Yale study.

Writing in the journal Nature Climate Change, Professor Nadine Unger of the Yale School of Forestry & Environmental Studies (F&ES) reports that large-scale forest losses during the last 150 years have reduced global emissions of biogenic volatile organic compounds (BVOCs), which control the atmospheric distribution of many short-lived climate pollutants, such as tropospheric ozone, methane, and aerosol particles.

Using sophisticated climate modeling, Unger calculated that a 30-percent decline in BVOC emissions between 1850 and 2000, largely through the conversion of forests to cropland, produced a net global cooling of about 0.1 degrees Celsius. During the same period, the global climate warmed by about 0.6 degrees Celsius, mostly due to increases in fossil fuel carbon dioxide emissions.

According to her findings, the climate impact of declining BVOC emissions is on the same magnitude as two other consequences of deforestation long known to affect global temperatures, although in opposing ways: carbon storage and the albedo effect. The lost carbon storage capacity caused by forest conversion has exacerbated global warming. Meanwhile, the disappearance of dark-colored forests has also helped offset temperature increases through the so-called albedo effect. (The albedo effect refers to the amount of radiation reflected by the surface of the planet. Light-colored fields, for instance, reflect more light and heat back into space than darker forests.)

Unger says the combined effects of reduced BVOC emissions and increased albedo may have entirely offset the warming caused by the loss of forest-based carbon storage capacity.

"Land cover changes caused by humans since the industrial and agricultural revolutions have removed natural forests and grasslands and replaced them with croplands," said Unger, an assistant professor of atmospheric chemistry at F&ES. "And croplands are not strong emitters of these BVOCs -- often they don't emit any BVOCs."

"Without doing an earth-system model simulation that includes these factors, we can't really know the net effect on the global climate. Because changes in these emissions affect both warming and cooling pollutants," she noted.

Unger said the findings do not suggest that increased forest loss provides climate change benefits, but rather underscore the complexity of climate change and the importance of better assessing which parts of the world would benefit from greater forest conservation.

Since the mid-19^th century, the percentage of the planet covered by cropland has more than doubled, from 14 percent to 37 percent. Since forests are far greater contributors of BVOC emissions than crops and grasslands, this shift in land use has removed about 30 percent of Earth's BVOC sources, Unger said.

Not all of these compounds affect atmospheric chemistry in the same way. Aerosols, for instance, contribute to global "cooling" since they generally reflect solar radiation back into space. Therefore, a 50 percent reduction in forest aerosols has actually spurred greater warming since the pre-industrial era.

However, reductions in the potent greenhouse gases methane and ozone -- which contribute to global warming -- have helped deliver a net cooling effect.

These emissions are often ignored in climate modeling because they are perceived as a "natural" part of Earth system, explained Unger. "So they don't get as much attention as human-generated emissions, such as fossil fuel VOCs," she said. "But if we change how much forest cover exists, then there is a human influence on these emissions."

These impacts have also been ignored in previous climate modeling, she said, because scientists believed that BVOC emissions had barely changed between the pre-industrial era and today. But a study published last year by Unger showed that emissions of these volatile compounds have indeed decreased. Studies by European scientists have produced similar results.

The impact of changes to ozone and organic aerosols are particularly strong in temperate zones, she said, while methane impacts are more globally distributed.

The sensitivity of the global climate system to BVOC emissions suggests the importance of establishing a global-scale long-term monitoring program for BVOC emissions, Unger noted.

Date:

September 8, 2014

Source:

Indiana University

Summary:

Three easy -- one could even say slow -- 5-minute walks can reverse harm caused to leg arteries during three hours of prolonged sitting, researchers report. Sitting for long periods of time is associated with risk factors such as higher cholesterol levels and greater waist circumference that can lead to cardiovascular and metabolic disease. When people sit, slack muscles do not contract to effectively pump blood to the heart. Blood can pool in the legs and affect the endothelial function of arteries, or the ability of blood vessels to expand from increased blood flow.

AN Indiana University study has found that three easy -- one could even say slow -- 5-minute walks can reverse harm caused to leg arteries during three hours of prolonged sitting.

Sitting for long periods of time, like many people do daily at their jobs, is associated with risk factors such as higher cholesterol levels and greater waist circumference that can lead to cardiovascular and metabolic disease. When people sit, slack muscles do not contract to effectively pump blood to the heart. Blood can pool in the legs and affect the endothelial function of arteries, or the ability of blood vessels to expand from increased blood flow.

This study is the first experimental evidence of these effects, said Saurabh Thosar, a postdoctoral researcher at Oregon Health & Science University, who led the study as a doctoral candidate at IU's School of Public Health-Bloomington.

"There is plenty of epidemiological evidence linking sitting time to various chronic diseases and linking breaking sitting time to beneficial cardiovascular effects, but there is very little experimental evidence," Thosar said. "We have shown that prolonged sitting impairs endothelial function, which is an early marker of cardiovascular disease, and that breaking sitting time prevents the decline in that function."

The researchers were able to demonstrate that during a three-hour period, the flow-mediated dilation, or the expansion of the arteries as a result of increased blood flow, of the main artery in the legs was impaired by as much as 50 percent after just one hour. The study participants who walked for 5 minutes each hour of sitting saw their arterial function stay the same -- it did not drop throughout the three-hour period. Thosar says it is likely that the increase in muscle activity and blood flow accounts for this.

"American adults sit for approximately eight hours a day," he said. "The impairment in endothelial function is significant after just one hour of sitting. It is interesting to see that light physical activity can help in preventing this impairment."

The study involved 11 non-obese, healthy men between the ages of 20-35 who participated in two randomized trials. In one trial they sat for three hours without moving their legs. Researchers used a blood pressure cuff and ultrasound technology to measure the functionality of the femoral artery at baseline and again at the one-, two- and three-hour mark.

In the second trial, the men sat during a three-hour period but also walked on a treadmill for 5 minutes at a speed of 2 mph at the 30-minute mark, 1.5-hour mark and 2.5-hour mark. Researchers measured the functionality of the femoral artery at the same intervals as in the other trial.

Brain mechanism underlying recognition of hand gestures develops even when blind

Date:

September 5, 2014

Source:

National Institutes of Natural Sciences

Summary:

Researchers have discovered that activated brain regions of congenitally blind individuals and activated brain regions of sighted individuals share common regions when recognizing human hand gestures. They indicated that a region of the neural network that recognizes others' hand gestures is formed in the same way even without visual information.

Brain mechanism underlying recognition of hand gestures develops even when blind

Does a distinctive mechanism work in the brain of congenitally blind individuals when understanding and learning others' gestures? Or does the same mechanism as with sighted individuals work? Japanese researchers figured out that activated brain regions of congenitally blind individuals and activated brain regions of sighted individuals share common regions when recognizing human hand gestures. They indicated that a region of the neural network that recognizes others' hand gestures is formed in the same way even without visual information.

The findings are discussed in The Journal of Neuroscience.

Our brain mechanism perceives human bodies from inanimate objects and shows a particular response. A part of a region of the "visual cortex" that processes visual information supports this mechanism. Since visual information is largely used in perception, this is reasonable, however, for perception using haptic information and also for the recognition of one's own gestures, it has been recently learned that the same brain region is activated. It came to be considered that there is a mechanism that is formed regardless of the sensory modalities and recognizes human bodies.

Blind and sighted individuals participated in the study of the research group of Assistant Professor Ryo Kitada of the National Institute for Physiological Sciences, National Institutes of Natural Sciences. With their eyes closed, they were instructed to touch plastic casts of hands, teapots, and toy cars and identify the shape. As it turned out, sighted individuals and blind individuals could make an identification with the same accuracy. Through measuring the activated brain region using functional magnetic resonance imaging (fMRI), for plastic casts of hands and not for teapots or toy cars, the research group was able to pinpoint a common activated brain region regardless of visual experience. On another front, it also revealed a region showing signs of activity that is dependent on the duration of the visual experience and it was also learned that this region functions as a supplement when recognizing hand gestures.

As Assistant Professor Ryo Kitada notes, "Many individuals are active in many parts of the society even with the loss of their sight as a child. Developmental psychology has been advancing its doctrine based on sighted individuals. I wish this finding will help us grasp how blind individuals understand and learn about others and be seen as an important step in supporting the development of social skills for blind individuals."

In one of nature's innovations, a single cell smashes and rebuilds its own genome

Date:

September 8, 2014

Source:

Princeton University

Summary:

A pond-dwelling, single-celled organism has the remarkable ability to break its own DNA into nearly a quarter-million pieces and rapidly reassemble those pieces when it's time to mate. This elaborate process could provide a template for understanding how chromosomes in more complex animals such as humans break apart and reassemble, as can happen during the onset of cancer.

A study led by Princeton University researchers found that the pond-dwelling, single-celled organism Oxytricha trifallax (above) has the remarkable ability to break its own DNA into nearly a quarter-million pieces and rapidly reassemble those pieces when it's time to mate. This elaborate process could provide a template for understanding how chromosomes in more complex animals such as humans break apart and reassemble, as can happen during the onset of cancer.

Life can be so intricate and novel that even a single cell can pack a few surprises, according to a study led by Princeton University researchers.

The pond-dwelling, single-celled organism Oxytricha trifallax has the remarkable ability to break its own DNA into nearly a quarter-million pieces and rapidly reassemble those pieces when it's time to mate, the researchers report in the journal Cell. The organism internally stores its genome as thousands of scrambled, encrypted gene pieces. Upon mating with another of its kind, the organism rummages through these jumbled genes and DNA segments to piece together more than 225,000 tiny strands of DNA. This all happens in about 60 hours.

The organism's ability to take apart and quickly reassemble its own genes is unusually elaborate for any form of life, explained senior author Laura Landweber, a Princeton professor of ecology and evolutionary biology. That such intricacy exists in a seemingly simple organism accentuates the "true diversity of life on our planet," she said.

"It's one of nature's early attempts to become more complex despite staying small in the sense of being unicellular," Landweber said. "There are other examples of genomic jigsaw puzzles, but this one is a leader in terms of complexity. People might think that pond-dwelling organisms would be simple, but this shows how complex life can be, that it can reassemble all the building blocks of chromosomes."

From a practical standpoint, Oxytricha is a model organism that could provide a template for understanding how chromosomes in more complex animals such as humans break apart and reassemble, as can happen during the onset of cancer, Landweber said. While chromosome dynamics in cancer cells can be unpredictable and chaotic, Oxytricha presents an orderly step-by-step model of chromosome reconstruction, she said.

"It's basically bad when human chromosomes break apart and reassemble in a different order," Landweber said. "The process in Oxytricha recruits some of the same biological mechanisms that normally protect chromosomes from falling apart and uses them to do something creative and constructive instead."

Gertraud Burger, a professor of biochemistry at the University of Montreal, said that the "rampant and diligently orchestrated genome rearrangements that take place in this organism" demonstrate a unique layer of complexity for scientists to consider when it comes to studying an organism's genetics.

"This work illustrates in an impressive way that the genetic information of an organism can undergo substantial change before it is actually used for building the components of a living cell," said Burger, who is familiar with the work but had no role in it.

"Therefore, inferring an organism's make-up from the genome sequence alone can be a daunting task and maybe even impossible in certain instances," Burger said. "A few cases of minor rearrangements have been described in earlier work, but these are dilettantes compared to [this] system."

Burger added that the work is "extremely comprehensive as to the experimental techniques employed and analyses performed." The project is one of the first complex genomes to be sequenced using Pacific Biosciences (PacBio) technology that reads long, single molecules.

Oxytricha already stands apart from other microorganisms, Landweber said. It is a large cell, about 10 times the size of a typical human cell. The organism also contains two nuclei whereas most single-celled organisms contain just one. A cell's nucleus regulates internal activity and, typically, contains the cell's DNA as well as the genes that are passed along during reproduction.

An individual Oxytricha cell, however, keeps its active DNA in one working nucleus and uses the second to store an archive of the genetic material it will pass along to the next generation, Landweber said. The genome of this second nucleus -- known as the germ-line nucleus -- undergoes the dismantling and reconstruction to produce a new working nucleus in the offspring.

Oxytricha uses sex solely to exchange DNA rather than to reproduce, Landweber said -- like plant cuttings, new Oxytricha populations spawn from a single organism. During sex, two organisms fuse together to share half of their genetic information. The object is for each cell to replace aging genes with new genes and DNA parts from its partner. Together, both cells construct new working nuclei with a fresh set of chromosomes. This rejuvenates them and diversifies their genetic material, which is good for the organism, Landweber said.

"It's kind of like science fiction -- they stop aging by trading in their old parts," she said.

It's during this process that the scrambled genes in the germ-line nucleus are sorted through to locate the roughly 225,000 small DNA segments that each mate uses to reconstruct its rejuvenated chromosomes, the researchers found. Previous work in Landweber's lab -- a 2012 publication in Cell and a 2008 paper in the journal Nature -- showed that millions of noncoding RNA molecules from the previous generation direct this undertaking by marking and sorting the DNA pieces in the correct order.

Also impressive is the massive scale of Oxytricha's genome, Landweber said. A 2013 paper from her lab in PLoS Biology reported that the organism contains approximately 16,000 chromosomes in the active nucleus; humans have only 46. Most of Oxytricha's chromosomes contain just a single gene, but even those genes can get hefty. A single Oxytricha gene can be built up from anywhere between one to 245 separate pieces of DNA, Landweber said.

The exceptional genetics of Oxytricha protect its DNA, so that mainly healthy material is passed along during reproduction, Landweber said. It's no wonder then that the organism can be found worldwide munching on algae.

"Their successful distribution across the globe has something to do with their ability to protect their DNA through a novel method of encryption, then rapidly reassemble and transmit robust genes across generations," Landweber said.

Landweber worked with, from her lab, first author Xiao Chen and Derek Clay, two graduate students in molecular biology, co-first author John Bracht and Aaron Goldman, postdoctoral fellows in ecology and evolutionary biology, and David Perlman, director of the molecular biology mass spectrometry facility. Other researchers on the paper are from the University of South Florida, the University of Bern in Switzerland, Indiana University, the Benaroya Research Institute at Virginia Mason in Seattle, and the Icahn School of Medicine at Mount Sinai.

The work was supported by the National Institutes of Health (grant nos. GM59708 and GM109459), the National Science Foundation (grant nos. 0900544 and 0923810), an NIH fellowship (1F32GM099462), and a NASA postdoctoral fellowship.

Rapid and urable protection against Ebola virus with new vaccine regimens

Date:

September 8, 2014

Source:

NIH/National Institute of Allergy and Infectious Diseases

Summary:

One shot of an experimental vaccine made from two Ebola virus gene segments incorporated into a chimpanzee cold virus vector, called chimp adenovirus type 3 or ChAd3, protected all four macaque monkeys exposed to high levels of Ebola virus 5 weeks after inoculation, report scientists.

One shot of an experimental vaccine made from two Ebola virus gene segments incorporated into a chimpanzee cold virus vector (called chimp adenovirus type 3 or ChAd3) protected all four macaque monkeys exposed to high levels of Ebola virus 5 weeks after inoculation, report National Institutes of Health (NIH) scientists and their collaborators.The ability of the ChAd3 Ebola virus vaccine to elicit rapid protection in monkeys is notable as the world health community battles an ongoing Ebola virus disease outbreak in West Africa. While the protective effects of the single shot waned over time, two out of four inoculated animals were protected when challenged with Ebola virus 10 months after vaccination.

The research team, headed by Nancy J. Sullivan, Ph.D., of the National Institute of Allergy and Infectious Diseases Vaccine Research Center, also demonstrated increased levels of durable protection using an additional vaccine. They inoculated four macaques first with the ChAd3 Ebola vaccine, then 8 weeks later with a booster vaccine containing Ebola virus gene segments incorporated into a different vector (a poxvirus).

Ten months after the initial inoculation, four out of four animals that received both shots were fully protected from infection with high doses of Ebola virus, demonstrating that the prime-boost regimen resulted in durable protection.

The research team included scientists from Okairos, a Swiss-Italian biotechnology company now part of GlaxoSmithKline, and the U.S. Army Medical Research Institute of Infectious Diseases. The experimental ChAd3 Ebola vaccine used in these non-human primate studies is the same one currently being tested in an early-stage human clinical trial at the NIH in Bethesda, Maryland.

Planet forming around star about 335 light years from Earth

Date:

September 8, 2014

Source:

Naval Research Laboratory

Summary:

Scientists have discovered what they believe is evidence of a planet forming around a star about 335 light years from Earth. Astronomers set out to study the protoplanetary disk around a star known as HD 100546, and as sometimes happens in scientific inquiry, it was by "chance" that they stumbled upon the formation of the planet orbiting this star.

An artist's conception of the young massive star HD100546 and its surrounding disk. A planet forming in the disk has cleared the disk within 13AU of the star, a distance comparable to that of Saturn from the sun. As gas and dust flows from the circumstellar disk to the planet, this material surrounds the planet as a circumplanetary disk (inset). These rotating disks are believed to be the birthplaces of planetary moons, such as the Galilean moons that orbit Jupiter. While they are theoretically predicted to surround giant planets at birth, there has been little observational evidence to date for circumplanetary disks outside the solar system. Brittain et al. (2014) report evidence for an orbiting source of carbon monoxide emission whose size is consistent with theoretical predictions for a circumplanetary disk. Observations over 10 years trace the orbit of the forming planet from behind the near side of the circumstellar disk in 2003 to the far side of the disk in 2013. These observations provide a new way to study how planets form.

Dr. John Carr, a scientist at the U.S. Naval Research Laboratory (NRL), is part of an international team that has discovered what they believe is evidence of a planet forming around a star about 335 light years from Earth. This research is published in the August 20th issue of The Astrophysical Journal.

Carr and the other research team members set out to study the protoplanetary disk around a star known as HD 100546, and as sometimes happens in scientific inquiry, it was by "chance" that they stumbled upon the formation of the planet orbiting this star. A protoplanetary disk, or circumstellar disk, is a very large disk of material orbiting a newly formed star out of which a planetary system may form. The team was studying the warm gas in this disk using a technique called spectro-astrometry, which allows astronomers to detect small changes in the position of moving gas.

The researchers discovered an "extra" source of gaseous emission from carbon monoxide molecules that could not be explained by the protoplanetary disk alone. By tracking the changes in velocity and position of this extra emission over the years of the observations, they were able to show that it is orbiting around the young star. The distance from the star is somewhat larger than the distance of Saturn from the Sun. The evidence suggests that they are observing hot gas that surrounds an orbiting young planet. Carr points out that rather than seeing the planet directly, they are detecting the gas as it swirls around and onto the forming planet.

Through modeling carried out by Dr. Sean Brittain, a Clemson University astrophysicist and the lead author on the paper, and with additional data gathered by the team to confirm their initial hypothesis, they were able to investigate the extra emission as it orbited the star. The authors concluded that a likely explanation for the observations is a small circumplanetary disk of hot gas orbiting a forming planet. The candidate planet would be a gas giant at least three times the mass of Jupiter. The theory is that material from the large protoplanetary disk feeds into the circumplanetary disk, which then feeds onto the growing planet. Hence, a circumplanetary disk plays a mediating role in the growth of the planet. The remnants of a circumplanetary disk could also give birth to moons, such as those seen around Jupiter in our solar system. As Carr explains, a novel aspect of this new evidence for planet formation is the possible detection of a circumplanetary disk.

The team's study is based on four sets of observations gathered in 2003, 2006, 2010, and 2013. They used the Gemini Observatory and the Very Large Telescope at the European Southern Observatory, both located in Chile. The Gemini Observatory consists of twin 8.1-meter diameter optical/infrared telescopes located on mountains in Hawaii and Chile. The VLT is not just one telescope, but an array of four, each with a main mirror of 8.2 meters in diameter. The data were collected using high-resolution infrared spectrographs that allowed precise measurements of the motions of molecular gas surrounding the star.

"These results provide a rare opportunity," Carr says, "to study planet formation in action. Our analysis strongly suggests we are observing a disk of hot gas that surrounds a forming giant planet in orbit around the star. While such circumplanetary disks have been theorized to surround giant planets at birth and to control the flow of gas onto the growing planet, these findings are the first observational evidence for their existence. If our interpretation is correct, we are essentially seeing a planet caught in the act of formation."

Looking ahead, the team would like to continue to monitor the motion of the planet and obtain additional data to better define the properties of the circumplanetary disk. They predict that the planet and its disk will disappear from view in about two years time when they become hidden by the inner edge of the circumstellar disk. So, if the team's model is correct, the signature of the orbiting planet will not be seen for another 15 years until its orbit brings it back into view.

Coral trout pick their collaborators carefully

Date:

September 8, 2014

Source:

Cell Press

Summary:

Coral trout not only work with moray eels to improve their chances of a meal, but they can also be choosy when it comes to picking the best moray partner. The findings show that such sophisticated collaborative abilities are not limited to apes and humans. The fish's behavior is remarkable in other ways too, the researchers say.

Coral trout not only work with moray eels to improve their chances of a meal, but they can also be choosy when it comes to picking the best moray partner. The findings reported in the Cell Press journal Current Biology on September 8 show that such sophisticated collaborative abilities are not limited to apes and humans.

The fish's behavior is remarkable in other ways too, the researchers say.

"The trout's collaboration appears to be relatively special, as it uses gestures to coordinate its hunts with partners of different species, such as morays, napoleon wrasse, and octopus," says Alexander Vail of the University of Cambridge.

Those other species are of more use to trout as hunting partners than members of its own species because the other species flush prey out of reef crevices in a way that the fish themselves can't, Vail explains. Their relationship to morays may be considered as social tool use: fish can't pick up a stick to pry something out of a crevice, but they can use intentional communication to manipulate the behavior of a suitable other species to achieve the same end-goal.

Chimpanzees are known to work with other chimpanzees to hunt in the wild, with individuals taking on different roles, such as chasers or blockers. Earlier studies have shown that chimpanzees also make good choices when it comes to selecting the best partner among their peers. Those collaborative skills have been interpreted as evidence for advanced cognitive processes in our closest primate relative, potentially representing the evolutionary origins of our complex human collaboration.

But Vail and his colleagues wondered whether those collaborative abilities might also be found in other, more distantly related species. They found the best candidate in a rather surprising place: among a genus of fishes known as Plectropomus. In fact, studies have shown that roving coral grouper fish will team up with moray eels, too. More recently, Vail found that coral trout also hunt collaboratively with moray eels on the Great Barrier Reef.

To examine the collaborative tendencies of the fish in greater detail, the researchers brought some of those fish back to the lab to test their interactions with moray eel decoys, one "good" and one "bad." The "good" moray would come to the coral trout's aid when signalled, whereas the "bad" one would swim in the opposite direction. In fact, some morays in nature are more helpful to trout than others.

By watching these interactions, the researchers found that trout were similarly proficient to chimpanzees at determining when to collaborate. The researchers' observations also showed that coral trout were quick to learn which moray eel model was the better collaborator.

As stunning as they are, the findings in fish may not prove as unique as they seem.

"Our study shows that these collaborative skills are not confined to apes and raises the possibility that they may be found in a number of other animal species for which they are ecologically relevant," Vail says.

Biologists delay the aging process by 'remote control'

Date:

September 8, 2014

Source:

University of California - Los Angeles

Summary:

Biologists have identified a gene that can slow the aging process when activated remotely in key organ systems. The life scientists, working with fruit flies, activated a gene called AMPK that is a key energy sensor in cells. Increasing AMPK in the intestine increased the fly's life by about 30 percent, and the fly stayed healthier longer as well. The research could have important implications for delaying aging and disease in humans.

Activating a gene called AMPK in the nervous system induces the anti-aging cellular recycling process of autophagy in both the brain and intestine. Activating AMPK in the intestine leads to increased autophagy in both the intestine and brain. Matthew Ulgherait, David Walker and UCLA colleagues showed that this 'inter-organ' communication during aging can substantially prolong the healthy 

UCLA biologists have identified a gene that can slow the aging process throughout the entire body when activated remotely in key organ systems.

Working with fruit flies, the life scientists activated a gene called AMPK that is a key energy sensor in cells; it gets activated when cellular energy levels are low.

Increasing the amount of AMPK in fruit flies' intestines increased their lifespans by about 30 percent -- to roughly eight weeks from the typical six -- and the flies stayed healthier longer as well.

The research, published Sept. 4 in the open-source journal Cell Reports, could have important implications for delaying aging and disease in humans, said David Walker, an associate professor of integrative biology and physiology at UCLA and senior author of the research.

"We have shown that when we activate the gene in the intestine or the nervous system, we see the aging process is slowed beyond the organ system in which the gene is activated," Walker said.

Walker said that the findings are important because extending the healthy life of humans would presumably require protecting many of the body's organ systems from the ravages of aging -- but delivering anti-aging treatments to the brain or other key organs could prove technically difficult. The study suggests that activating AMPK in a more accessible organ such as the intestine, for example, could ultimately slow the aging process throughout the entire body, including the brain.

Humans have AMPK, but it is usually not activated at a high level, Walker said.

"Instead of studying the diseases of aging -- Parkinson's disease, Alzheimer's disease, cancer, stroke, cardiovascular disease, diabetes -- one by one, we believe it may be possible to intervene in the aging process and delay the onset of many of these diseases," said Walker, a member of UCLA's Molecular Biology Institute. "We are not there yet, and it could, of course, take many years, but that is our goal and we think it is realistic.

"The ultimate aim of our research is to promote healthy aging in people."

The fruit fly, Drosophila melanogaster, is a good model for studying aging in humans because scientists have identified all of the fruit fly's genes and know how to switch individual genes on and off. The biologists studied approximately 100,000 of them over the course of the study.

Lead author Matthew Ulgherait, who conducted the research in Walker's laboratory as a doctoral student, focused on a cellular process called autophagy, which enables cells to degrade and discard old, damaged cellular components. By getting rid of that "cellular garbage" before it damages cells, autophagy protects against aging, and AMPK has been shown previously to activate this process.

Ulgherait studied whether activating AMPK in the flies led to autophagy occurring at a greater rate than usual.

"A really interesting finding was when Matt activated AMPK in the nervous system, he saw evidence of increased levels of autophagy in not only the brain, but also in the intestine," said Walker, a faculty member in the UCLA College. "And vice versa: Activating AMPK in the intestine produced increased levels of autophagy in the brain -- and perhaps elsewhere, too."

Many neurodegenerative diseases, including both Alzheimer's and Parkinson's, are associated with the accumulation of protein aggregates, a type of cellular garbage, in the brain, Walker noted.

"Matt moved beyond correlation and established causality," he said. "He showed that the activation of autophagy was both necessary to see the anti-aging effects and sufficient; that he could bypass AMPK and directly target autophagy."

Walker said that AMPK is thought to be a key target of metformin, a drug used to treat Type 2 diabetes, and that metformin activates AMPK.

The research was funded by the National Institutes of Health's National Institute on Aging (grants R01 AG037514 and R01 AG040288). Ulgherait received funding support from a Ruth L. Kirschstein National Research Service Award (GM07185) and Eureka and Hyde fellowships from the UCLA department of integrative biology and physiology.

Co-authors of the research were Anil Rana, a postdoctoral scholar in Walker's lab; Michael Rera, a former UCLA postdoctoral scholar in Walker's lab; and Jacqueline Graniel, who participated in the research as a UCLA undergraduate.

Paleontologists discover new species of titanosaurian dinosaur in Tanzania

Date:

September 8, 2014

Source:

Ohio University

Summary:

Paleontologists have identified a new species of titanosaurian, a member of the large-bodied sauropods that thrived during the final period of the dinosaur age, in Tanzania. Although many fossils of titanosaurians have been discovered around the globe, especially in South America, few have been recovered from the continent of Africa.

An artistic rendering of a deceased Rukwatitan bisepultus individual in the initial floodplain depositional setting from which the holotypic skeleton was recovered

Ohio University paleontologists have identified a new species of titanosaurian, a member of the large-bodied sauropods that thrived during the final period of the dinosaur age, in Tanzania. Although many fossils of titanosaurians have been discovered around the globe, especially in South America, few have been recovered from the continent of Africa.

.The new species, named Rukwatitan bisepultus, was first spotted by scientists embedded in a cliff wall in the Rukwa Rift Basin of southwestern Tanzania. Using the help of professional excavators and coal miners, the team unearthed vertebrae, ribs, limbs and pelvic bones over the course of two field seasons.

CT scans of the fossils, combined with detailed comparisons with other sauropods, revealed unique features that suggested an animal that was different from previous finds -- including those from elsewhere in Africa, according to a study the team published today in the Journal of Vertebrate Paleontology.

"Using both traditional and new computational approaches, we were able to place the new species within the family tree of sauropod dinosaurs and determine both its uniqueness as a species and to delineate others species with which it is most closely related," said lead author Eric Gorscak, a doctoral student in biological sciences at Ohio University.

Rukwatitan bisepultus lived approximately 100 million years ago during the middle of the Cretaceous Period. Titanosaurian sauropods, the group that includes Rukwatitan, were herbivorous dinosaurs known for their iconic large body sizes, long necks and wide stance. Although not among the largest of titanosaurians, Rukwatitan is estimated to have a forelimb reaching 2 meters and may have weighed as much as several elephants.

The dinosaur's bones exhibit similarities with another titanosaurian, Malawisaurus dixeyi, previously recovered in Malawi. But the two southern African dinosaurs are distinctly different from one another, and, most notably, from titanosaurians known from northern Africa, said co-author Patrick O'Connor, a professor of anatomy in the Ohio University Heritage College of Osteopathic Medicine.

The fossils of middle Cretaceous crocodile relatives from the Rukwa Rift Basin also exhibit distinctive features when compared to forms from elsewhere on the continent.

"There may have been certain environmental features, such as deserts, large waterways and/or mountain ranges, that would have limited the movement of animals and promoted the evolution of regionally distinct faunas," O'Connor said. "Only additional data on the faunas and paleo environments from around the continent will let us further test such hypotheses."

In addition to providing new data about species evolution in sub-Saharan Africa, the study also contributes to fleshing out the global portrait of titanosaurians, which lived in habitats across the globe through the end of the Cretaceous Period. Their rise in diversity came in the wake of the decline of another group of sauropods, the diplodocoids, which include the dinosaur Apatosaurus, the researchers noted. Scientists have found fossils for more than 30 titanosaurians in South America compared to just four in Africa.

"Much of what we know regarding titanosaurian evolutionary history stems from numerous discoveries in South America -- a continent that underwent a steady separation from Africa during the first half of the Cretaceous Period," Gorscak said. "With the discovery of Rukwatitan and study of the material in nearby Malawi, we are beginning to fill a significant gap from a large part of the world."

Co-authors on the study are Nancy Stevens, a professor in the Ohio University Heritage College of Osteopathic Medicine, and Eric Roberts, a senior lecturer in the James Cook University of Australia.

The study was funded by the National Science Foundation, the National Geographic Society, the Ohio University Heritage College of Osteopathic Medicine and the Ohio University Office of the Vice President for Research and Creative Activity

Textbook theory behind volcanoes may be wrong

Date:

September 8, 2014

Source:

California Institute of Technology

Summary:

In the typical textbook picture, volcanoes, such as those that are forming the Hawaiian islands, erupt when magma gushes out as narrow jets from deep inside Earth. But that picture is wrong, according to a new study from researchers who conclude that seismology data are now confirming that such narrow jets don't actually exist.

In the typical textbook picture, volcanoes, such as those that are forming the Hawaiian islands, erupt when magma gushes out as narrow jets from deep inside Earth. But that picture is wrong, according to a new study from researchers at Caltech and the University of Miami in Florida.
New seismology data are now confirming that such narrow jets don't actually exist, says Don Anderson, the Eleanor and John R. McMillian Professor of Geophysics, Emeritus, at Caltech. In fact, he adds, basic physics doesn't support the presence of these jets, called mantle plumes, and the new results corroborate those fundamental ideas.

"Mantle plumes have never had a sound physical or logical basis," Anderson says. "They are akin to Rudyard Kipling's 'Just So Stories' about how giraffes got their long necks."

Anderson and James Natland, a professor emeritus of marine geology and geophysics at the University of Miami, describe their analysis online in the September 8 issue of the Proceedings of the National Academy of Sciences.

According to current mantle-plume theory, Anderson explains, heat from Earth's core somehow generates narrow jets of hot magma that gush through the mantle and to the surface. The jets act as pipes that transfer heat from the core, and how exactly they're created isn't clear, he says. But they have been assumed to exist, originating near where Earth's core meets the mantle, almost 3,000 kilometers underground -- nearly halfway to the planet's center. The jets are theorized to be no more than about 300 kilometers wide, and when they reach the surface, they produce hot spots.

While the top of the mantle is a sort of fluid sludge, the uppermost layer is rigid rock, broken up into plates that float on the magma-bearing layers. Magma from the mantle beneath the plates bursts through the plate to create volcanoes. As the plates drift across the hot spots, a chain of volcanoes forms -- such as the island chains of Hawaii and Samoa.

"Much of solid-Earth science for the past 20 years -- and large amounts of money -- have been spent looking for elusive narrow mantle plumes that wind their way upward through the mantle," Anderson says.

To look for the hypothetical plumes, researchers analyze global seismic activity. Everything from big quakes to tiny tremors sends seismic waves echoing through Earth's interior. The type of material that the waves pass through influences the properties of those waves, such as their speeds. By measuring those waves using hundreds of seismic stations installed on the surface, near places such as Hawaii, Iceland, and Yellowstone National Park, researchers can deduce whether there are narrow mantle plumes or whether volcanoes are simply created from magma that's absorbed in the sponge-like shallower mantle.

No one has been able to detect the predicted narrow plumes, although the evidence has not been conclusive. The jets could have simply been too thin to be seen, Anderson says. Very broad features beneath the surface have been interpreted as plumes or super-plumes, but, still, they're far too wide to be considered narrow jets.

But now, thanks in part to more seismic stations spaced closer together and improved theory, analysis of the planet's seismology is good enough to confirm that there are no narrow mantle plumes, Anderson and Natland say. Instead, data reveal that there are large, slow, upward-moving chunks of mantle a thousand kilometers wide.

In the mantle-plume theory, Anderson explains, the heat that is transferred upward via jets is balanced by the slower downward motion of cooled, broad, uniform chunks of mantle. The behavior is similar to that of a lava lamp, in which blobs of wax are heated from below and then rise before cooling and falling. But a fundamental problem with this picture is that lava lamps require electricity, he says, and that is an outside energy source that an isolated planet like Earth does not have.

The new measurements suggest that what is really happening is just the opposite: Instead of narrow jets, there are broad upwellings, which are balanced by narrow channels of sinking material called slabs. What is driving this motion is not heat from the core, but cooling at Earth's surface. In fact, Anderson says, the behavior is the regular mantle convection first proposed more than a century ago by Lord Kelvin. When material in the planet's crust cools, it sinks, displacing material deeper in the mantle and forcing it upward.

"What's new is incredibly simple: upwellings in the mantle are thousands of kilometers across," Anderson says. The formation of volcanoes then follows from plate tectonics -- the theory of how Earth's plates move and behave. Magma, which is less dense than the surrounding mantle, rises until it reaches the bottom of the plates or fissures that run through them. Stresses in the plates, cracks, and other tectonic forces can squeeze the magma out, like how water is squeezed out of a sponge. That magma then erupts out of the surface as volcanoes. The magma comes from within the upper 200 kilometers of the mantle and not thousands of kilometers deep, as the mantle-plume theory suggests.

"This is a simple demonstration that volcanoes are the result of normal broad-scale convection and plate tectonics," Anderson says. He calls this theory "top-down tectonics," based on Kelvin's initial principles of mantle convection. In this picture, the engine behind Earth's interior processes is not heat from the core but cooling at the planet's surface. This cooling and plate tectonics drives mantle convection, the cooling of the core, and Earth's magnetic field. Volcanoes and cracks in the plate are simply side effects.

The results also have an important consequence for rock compositions -- notably the ratios of certain isotopes, Natland says. According to the mantle-plume idea, the measured compositions derive from the mixing of material from reservoirs separated by thousands of kilometers in the upper and lower mantle. But if there are no mantle plumes, then all of that mixing must have happened within the upwellings and nearby mantle in Earth's top 1,000 kilometers.

The paper is titled "Mantle updrafts and mechanisms of oceanic volcanism."