Elusive songbird, the Liberian greenbul, may have never existed

Oct. 5 (UPI) — Ornithologists may have spent three decades looking for a bird that never was.

According to a new study published in the Journal of Ornithology, the elusiveness of the Liberian greenbul, the rarest of songbirds, can be explained by its lack of existence.

Scientists didn’t invent the Liberian greenbul, Phyllastrephus leucolepis, out of thin air. In the early 1980s, researchers spotted what they believed to be a new species, but were only able to collect a single specimen, similar to the Icterine greenbul but with distinctive white markings on its feathers.

The ornithologists decided they had discovered a new species. For the last 30 years or so, the specimen has remained the sole evidence of Liberian greenbul’s existence. Liberia’s civil war made followup expeditions difficult, but surveys in 2010 and 2013 turned up no signs of the species.

Now, scientists have an explanation for the bird’s elusiveness. It never existed.

New DNA analysis by experts at the University of Aberdeen, in Scotland, suggests the specimen’s genome isn’t significantly different than that of the Icterine greenbul. Researchers hypothesized that the sole specimen is likely just an Icterine greenbul with an odd plumage variation, possibly caused by a nutritional deficiency.

Previous surveys have measured significantly genetic differences among other species of greenbul, offering further proof that the Liberian greenbul and Icterine greenbul are indeed the same.

“The Liberian Greenbul has gained almost ‘mythical’ status since it was sighted in the ’80s,” Martin Collinson, a geneticist from the University of Aberdeen’s Institute of Medical Sciences, said in a news release. “We can’t say definitively that the Liberian Greenbul is the same bird as the Iceterine Greenbul but we have presented enough evidence that makes any other explanation seem highly unlikely. The genetic work was performed independently by scientists here in Aberdeen and in Dresden to make sure there could be no error — we both came to the same conclusion.”

West Africa’s Cavalla Forest, where the single Liberian greenbul specimen was collected, is treasured as a haven of biodiversity. It is of ecological significant to a variety of threatened bird species.

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NASA pushes back launch date for James Webb Space Telescope, again

Sept. 29 (UPI) — NASA’s new target window for the launch of the James Webb Space Telescope is between March and June 2019. The world’s most powerful space telescope was previously scheduled to launch in October 2018.

“The change in launch timing is not indicative of hardware or technical performance concerns,” Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at the agency’s D.C. headquarters, announced in a news release this week. “Rather, the integration of the various spacecraft elements is taking longer than expected.”

An international agreement with the European Space Agency required NASA to analyze the telescope’s launch preparedness one year prior to the launch date. The assessment forced officials to reconsider their plans, and ultimately inspired NASA to push back the launch date once more.

JWST, the successor to the Hubble Space Telescope, was first conceived of in 1996. Along the way, the project has been replanned several times, each time pushing the target launch date backward — from 2011 to 2013, from 2015 to 2018 and now to the spring of 2019.

Scientists say the latest delay is largely the result of the complexity of the space telescope’s sunshield.

“The combination of some integration activities taking longer than initially planned, such as the installation of more than 100 sunshield membrane release devices, factoring in lessons learned from earlier testing, like longer time spans for vibration testing, has meant the integration and testing process is just taking longer,” said Eric Smith, program director for the James Webb Space Telescope at NASA’s headquarters.

Unlike Hubble, which can be serviced by astronauts and have instruments swapped in and out, JWST must be in its final form before launch.

The construction of such a massive and complex telescope has been a lengthy process. NASA had to build new facilities in which to build and test the groundbreaking telescope — a painstaking and expensive process that may never be repeated.

“This may be the last [space] telescope that we build that is not modular,” NASA administrator Charles Boldentold reporters last year.

Once it begins its scientific mission, though, astronomers are sure to rejoice as they begin to field giant troves of rich astronomical data.

The telescope’s 18 hexagonal mirrors will field massive amounts of infrared light, allowing scientists to peer deeper into space with greater clarity and to study the universe’s first generation of stars and galaxies. JWST will also help scientists study the habitability of nearby exoplanets.

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New laser sensor could detect explosives, dangerous gases more quickly

Sept. 29 (UPI) — Scientists have developed a new laser-based spectroscopic method for identifying potentially dangerous gasses. The method, which relies on the combination of two spectroscopic techniques, could be used to more quickly and accurately identify explosives and other dangerous substances.

The first technique, called multi-dimensional coherent spectroscopy, relies on short laser pulses. When bounced through a mixture of gases, scientists can measure which wavelengths are absorbed and use their observations to identify the gas molecules.

“If you have light going through the gas, and, for example, you use a prism to separate white light into colored light, in the rainbow spectrum you’d see there’d be black stripes,” Steven Cundiff, a physics professor at the University of Michigan, said in a news release. “Where the black stripes are almost gives you a barcode that tells you what kind of molecule is in the sample.”

Similar methods have previously been used to identify single gas samples, but a more complex method was needed to analyze gas mixtures. Until now, scientists have had to rely on supercomputers to reference catalogues of molecular data when analyzing gas mixtures.

“It’s like trying to look at three people’s fingerprints on top of each other. This is a stumbling block for using these methods in a real-world situation,” Cundiff said. “Our method takes about 15 minutes to a few hours using traditional approaches to MDCS.”

Scientists accelerated the processing time by marrying MDCS with another method called dual comb spectroscopy. Frequency combs produce a spectrum of sharp, equally spaced frequency lines. The lines work like a ruler and are used to measure the optical frequencies of atoms and molecules. A pair of combs can be combined to efficiently analyze the spectral qualities of a collection of molecules.

“This approach could allow the method of multidimensional coherent spectroscopy to escape the lab and be used for practical applications such as detecting explosives or monitoring atmospheric constituents,” Cundiff said.

Cundiff and his Michigan colleague, Bachana Lomsadze, used their newly developed method to analyze a sample of rubidium atoms featuring a mix of atomic isotopes. The spectral difference between the two isotopes are too subtle to be measured using MDCS alone. But when researchers combine MDCS with a pair of frequency combs, they were able to accurately identify the different spectral lines produced but the two isotopes.

Cundiff, Lomsadze and their fellow researchers detailed their work in a new paper, published this week in the journal Science. The scientists plan to add a third laser in subsequent tests to further speed up the identification process.

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Scientists are successfully breeding disease-resistance into mosquitoes

Sept. 29 (UPI) — While other mosquito-borne diseases have captured headlines in recent years, malaria remains the most problematic. Every year, several hundred million people become infected and a few hundred thousand perish.

But a recent breakthrough in the genetic modification could help breed disease-resistance into mosquito populations and eradicate malaria altogether.

Malaria is caused by a parasitic protozoan called Plasmodium that lives in the guts of mosquitoes. Humans can become infected when bitten by a mosquito carrying the parasite. To stop the disease in its tracks, scientists have been genetically modifying mosquitoes to make the insects resistant to the parasite.

While researchers have enjoyed success in breeding malaria-resistant mosquitoes in the lab, scientists were concerned the GM mosquitoes might suffer from a reduce libido or be unable to pass their disease-resistant traits onto offspring in the wild.

But a new study, published this week in the journal Science, suggests their methods translate to success in the wild. In tests, GM mosquitoes successfully mated with wild mosquitoes and passed along their disease-resistant trait.

“Ninety percent of the offspring in each generation passed along the GM trait,” scientists explained in an NIH press release. “Even when combining 10 percent GM with 90 percent wild mosquitoes, the Plasmodium-resistance trait dominated after a few generations. Importantly, the GM mosquitoes maintained their resistance to the malaria parasite for 7 years.”

Additionally, scientists found GM mosquitoes didn’t suffer from a reduced libido. Instead, GM males proved more interested in mating with wild females, and GM females were more interested in wild males.

“These preferences contributed to the spread of the desired protective trait within the mosquito population,” researchers wrote.

While the latest tests involved wild mosquitoes, the experiments were still conducted in the lab. To better gauge the potential of the disease fighting method, scientists plan to unleash GM mosquitoes in the wild during future tests.

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Study: To prevent flood damage and siltation, give rivers room to flow

Sept. 27 (UPI) — New research out of Germany suggests efforts to curb erosion aren’t sufficient to prevent severe siltation in rivers.

In a paper published this week in the journal Land Degradation and Development, scientists at the Technical University of Munich argue siltation will remain a problem as long as rivers are straightjacketed and denied the freedom to twist and bend.

“The prevention of erosion alone, as water and fisheries management have long demanded, does not then help river beds,” Karl Auerswald, an ecologist at TUM, said in a news release.

Auerswald and his colleagues have spent the past several years sampling the sediments accumulating at the bottom of Moosach, a tributary of the river Isar near Munich. Their analysis suggests erosion mitigation efforts have done little to prevent the problems caused by siltation.

Siltation is the flow of silt and sediment into the river. The particles become suspended in the river and accumulate on the riverbed. Siltation causes problems for fish, mussels and other aquatic organisms.

Oxygen-filled cavities between gravel on the riverbed are essential for many microorganisms. Fish also used the cavities to lay their eggs. But these gaps are often filled up by sediment.

The latest research suggests this problem will persist — even as erosion is reduced — as long as rivers are confined and straightened. According to Auerswald, Moosach is no longer a river as much as it is a canal-like channel. The diagnosis holds true for rivers throughout Germany and the world, researchers say.

Given room to roam, rivers can handle moderate amounts of siltation.

“The entry of erosion material also occurs under natural conditions,” Auerswald said. “Under natural conditions, however, the riverbed is constantly being relocated and the cavity system is cleared from the inundated floodplain by the groundwater flow.”

Exasperating the problems of river-straightjacketing and uncontrolled siltation are the lack of floodplains and buffering habitat. The human development and engineering that has squeezed rivers into straight lines, Auerswald warns, has also removed buffer of zones of vegetation that help prevent flood damage and erosion.

The solution to the problem, researchers argue, is fairly simple: leave rivers alone and give them space.

“Whatever floodplains are still around must absolutely be off-limits,” Auerswald said. “We would do well to allow the rivers to meander on their own again.”

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Appetite-controlling brain cells identified in new study

Sept. 27 (UPI) — Scientists at the University of Warwick, in England, have identified brain cells key to appetite control. The discovery, detailed this week in the journal Molecular Metabolism, could revolutionize dieting.

Researchers found brain cells called tanycytes react with amino acids found in food. The cells, found in the part of the brain that controls energy levels, use the same receptors that sense flavors in the tongue’s taste buds.

Tanycytes receive information from the amino acids about the food a person has just consumed. The cells react most readily with the amino acids arginine and lysine. Scientists hypothesize these reactions make a person feel more full.

Foods rich in arginine and lysine include pork shoulder, beef sirloin steak, chicken, mackerel, plums, apricots, avocadoes, lentils and almonds — all of which will satiate the consumer more quickly.

In the lab, researchers added fluorescent markers to arginine and lysine and added them to brain cells. The markers revealed chemical activity when the amino acids interacted with tanycytes, brain cells previously linked with appetite and weight.

When researchers blocked umami taste receptors in the brain cells, the tanycytes were not able to receive information from the amino acids.

“Amino acid levels in blood and brain following a meal are a very important signal that imparts the sensation of feeling full,” Warwick neuroscientist Ted Pridgeon said in a news release. “Finding that tanycytes, located at the center of the brain region that controls body weight, directly sense amino acids has very significant implications for coming up with new ways to help people to control their body weight within healthy bounds.”

The research suggests dieters would do well to eat more foods rich in arginine, lysine and other amino acids that encourage the feeling of being full. The findings could also inspire new drugs and supplements to help suppress appetite in patients prone to overeating.

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