Sweet potatoes didn't originate in the Americas as previously thought

A) Modern distribution of the sweet potato family (yellow line) and genus (white line). B) Fossil leaf of Ipomoea meghalayensis. C) Modern leaf of Ipomoea eriocarpa, showing similar size, shape and vein pattern.

Sweet potatoes may seem as American as Thanksgiving, but scientists have long debated whether their plant family originated in the Old or New World. New research by an Indiana University paleobotanist suggests it originated in Asia, and much earlier than previously known.

IU Bloomington emeritus professor David Dilcher and colleagues in India identified 57-milion-year-old leaf fossils from eastern India as being from the morning glory family, which includes sweet potatoes and many other plants. The research suggests the family originated in the late Paleocene epoch in the East Gondwana land mass that became part of Asia.

"I think this will change people's ideas," Dilcher said. "It will be a data point that is picked up and used in other work where researchers are trying to find the time of the evolution of major groups of flowering plants."

Previous fossil evidence had suggested the morning glory family may have originated in North America about 35 million years ago. But molecular analyses had supported the idea that it originated earlier and in the Old World. The new research provides evidence for that conclusion.

The discovery also suggests the morning glory family and the nightshade family, which includes potatoes and tomatoes, diverged earlier than previously thought. Together with the recent, separate discovery of 52-million-year-old nightshade fossils in Argentina, it suggests that morning glories developed in the East and nightshades in the West.

The 17 fossils analyzed in the study are the earliest recorded fossils for both the morning glory family, known as Convolvulaceae, and the order Solanales, which includes morning glories and nightshades. Morning glory fossils are rare because the plants' soft structure was not easily preserved in rocks.

Dilcher's collaborators, Gaurav Srivastava and Rakesh C. Mehrotra of India's Birbal Sahni Institute of Palaeosciences, discovered the fossils in Meghalaya, a state in northeastern India.

The researchers used microscopic analysis of the shape and structure of the leaves, comparing details of the leaf veins and cells with plants in the genus Ipomoea. Using such analysis to examine evolutionary relationships has been a hallmark of Dilcher's paleobotany research career.

The leaves the researchers studied are in the genus Ipomoea, which includes sweet potato but also hundreds of other plants, most of which don't produce food for humans.

"We don't know that these were sweet potatoes," said Dilcher, emeritus professor in the Department of Earth and Atmospheric Sciences and the Department of Biology in the IU Bloomington College of Arts and Sciences. "We can't say there were delicious sweet potatoes there. There may have been, or there may not."

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Michael Jackson's antigravity tilt -- Talent, magic, or a bit of both?

When was the last time you watched a Michael Jackson music video? If your answer is "never" or "not for quite a while," you are really missing a treat. According to Rolling Stone, "No single artist ... shaped, innovated or defined the medium of 'music video' more than Michael Jackson."

Back in the 1980s and early 1990s, MTV had only one format -- music videos -- and that genre really took off when Jackson burst on the scene in 1983 with his musical hit "Billie Jean." Prior to his arrival on MTV, most videos were merely visual promos for artists' songs, and in some cases the visual side of the promos detracted from the music. Michael Jackson, on the other hand, took his incredible music and added story lines, special effects, cinematography, and amazing choreography. He created high-budget brief movies highlighting both music and dance.

And about that dance. . . . Jackson executed dance moves we thought impossible, at the time and even now. Almost every fan tried to dance like him, but very few could pull it off. Some of Jackson's dance moves appear to defy the laws of gravity. In one move featured in his 1987 music video "Smooth Criminal," he pitches forward 45 degrees, with his body straight as a rod and his shoes resting on the stage, and holds the position. That is not how the human body works! How did Michael Jackson do it? Was it talent, magic, or both?

Three neurosurgeons from the Postgraduate Institute of Medical Education and Research in Chandigarh, India -- Nishant S. Yagnick, Manjul Tripathi, and Sandeep Mohindra -- set out to examine the antigravity tilt introduced in "Smooth Criminal" from a neurosurgeon's point of view.

First, Yagnick et al. walk us through some basics of spinal biomechanics to show just how impressive is the feat. Even the strongest of dancers can only maintain a 25- to 30-degree forward tilt from the ankle.

Admitted fans of Jackson, the neurosurgeons document how the antigravity tilt was accomplished, taking into account the talent and core strength of the artist, as well as his inventiveness and use of a patented aid, that together seem to move his body past human limits. They also warn other neurosurgeons of new forms of spinal injuries, as dancers follow Jackson's example and attempt "to jump higher, stretch further, and turn faster than ever before."

The full story on the antigravity tilt is published today in a new article in the Journal of Neurosurgery entitled "How did Michael Jackson challenge our understanding of spine biomechanics?."

Read the article soon. This is one of those mysteries where the solution is as fascinating as the performance. After you've read the article, you may want to go to YouTube and check out "Smooth Criminal" and other Michael Jackson music videos.

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Hotter bodies fight infections and tumors better -- researchers show how

Slight rise in temperature and inflammation - such as a fever - speeds up cellular 'clock' in which proteins switch genes on and off to respond to infection.

The hotter our body temperature, the more our bodies speed up a key defence system that fights against tumours, wounds or infections, new research by a multidisciplinary team of mathematicians and biologists from the Universities of Warwick and Manchester has found.

The researchers have demonstrated that small rises in temperature (such as during a fever) speed up the speed of a cellular 'clock' that controls the response to infections -- and this new understanding could lead to more effective and fast-working drugs which target a key protein involved in this process.

Biologists found that inflammatory signals activate 'Nuclear Factor kappa B' (NF-κB) proteins to start a 'clock' ticking, in which NF-κB proteins move backwards and forwards into and out of the cell nucleus, where they switch genes on and off.

This allows cells to respond to a tumour, wound or infection. When NF-κB is uncontrolled, it is associated with inflammatory diseases, such as Crohn's disease, psoriasis and rheumatoid arthritis.

At a body temperature of 34 degrees, the NF-κB clock slows down. At higher temperatures than the normal 37 degree body temperature (such as in fever, 40 degrees), the NF-κB clock speeds up.

Mathematicians at the University of Warwick's Systems Biology Centre calculated how temperature increases make the cycle speed up.

They predicted that a protein called A20 -- which is essential to avoid inflammatory disease -- might be critically involved in this process. The experimentalists then removed A20 from cells and found that the NF-kB clock lost its sensitivity to increases in temperature.

Lead mathematician Professor David Rand, Professor of Mathematics and a member of the University of Warwick's Zeeman Institute for Systems Biology and Infectious Disease Epidemiology (SBIDER), explained that in normal life the 24 hour body clock controls small (1.5 degree) changes in body temperature.

He commented: "the lower body temperature during sleep might provide a fascinating explanation into how shift work, jet lag or sleep disorders cause increased inflammatory disease"

Mathematician Dan Woodcock from the University of Warwick said: "this is a good example of how mathematical modelling of cells can lead to useful new biological understanding."

While the activities of many NF-kB controlled genes were not affected by temperature, a key group of genes showed altered profiles at the different temperatures. These temperature sensitive genes included key inflammatory regulators and controllers of cell communication that can alter cell responses.

This study shows that temperature changes inflammation in cells and tissues in a biologically organised way and suggests that new drugs might more precisely change the inflammatory response by targeting the A20 protein.

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Major fossil study sheds new light on emergence of early animal life 540 million years ago

These are exceptionally preserved soft-bodied fossils of the Cambrian predator and stem-lineage euarthropod Anomalocaris canadensis from the Burgess Shale, Canada. Top left: Frontal appendage showing segmentation similar to modern-day euarthropods. Bottom right: Full body specimen showing one pair of frontal appendages (white arrows) and mouthparts consisting of plates with teeth (black arrow) on the head.

All the major groups of animals appear in the fossil record for the first time around 540-500 million years ago -- an event known as the Cambrian Explosion -- but new research from the University of Oxford in collaboration with the University of Lausanne suggests that for most animals this 'explosion' was in fact a more gradual process.

The Cambrian Explosion produced the largest and most diverse grouping of animals the Earth has ever seen: the euarthropods. Euarthropoda contains the insects, crustaceans, spiders, trilobites, and a huge diversity of other animal forms alive and extinct. They comprise over 80 percent of all animal species on the planet and are key components of all of Earth's ecosystems, making them the most important group since the dawn of animals over 500 million years ago.

A team based at Oxford University Museum of Natural History and the University of Lausanne carried out the most comprehensive analysis ever made of early fossil euarthropods from every different possible type of fossil preservation. In an article published today in the Proceedings of the National Academy of Sciences they show that, taken together, the total fossil record shows a gradual radiation of euarthropods during the early Cambrian, 540-500 million years ago.

The new analysis presents a challenge to the two major competing hypotheses about early animal evolution. The first of these suggests a slow, gradual evolution of euarthropods starting 650-600 million years ago, which had been consistent with earlier molecular dating estimates of their origin. The other hypothesis claims the nearly instantaneous appearance of euarthropods 540 million years ago because of highly elevated rates of evolution.

The new research suggests a middle-ground between these two hypotheses, with the origin of euarthropods no earlier than 550 million years ago, corresponding with more recent molecular dating estimates, and with the subsequent diversification taking place over the next 40 million years.

"Each of the major types of fossil evidence has its limitation and they are incomplete in different ways, but when taken together they are mutually illuminating and allow a coherent picture to emerge of the origin and radiation of the euarthropods during the lower to middle Cambrian," explains Professor Allison Daley, who carried out the work at Oxford University Museum of Natural History and at the University of Lausanne. "This indicates that the Cambrian Explosion, rather than being a sudden event, unfolded gradually over the ~40 million years of the lower to middle Cambrian."

The timing of the origin of Euarthropoda is very important as it affects how we view and interpret the evolution of the group. By working out which groups developed first we can trace the evolution of physical characteristics, such as limbs.

It has been argued that the absence of euarthropods from the Precambrian Period, earlier than around 540 million years ago, is the result of a lack of fossil preservation. But the new comprehensive fossil study suggests that this isn't the case.

"The idea that arthropods are missing from the Precambrian fossil record because of biases in how fossils are preserved can now be rejected," says Dr Greg Edgecombe FRS from the Natural History Museum, London, who was not involved in the study. "The authors make a very compelling case that the late Precambrian and Cambrian are in fact very similar in terms of how fossils preserve. There is really just one plausible explanation -- arthropods hadn't yet evolved."

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Lightning in the eyewall of a hurricane beamed antimatter toward the ground

Hurricane Patricia was the most intense tropical cyclone ever recorded in the Western Hemisphere as it approached the west coast of Mexico in 2015. Researchers detected a reverse positron beam from a terrestrial gamma-ray flash associated with lightning in the eyewall of the hurricane.

Hurricane Patricia, which battered the west coast of Mexico in 2015, was the most intense tropical cyclone ever recorded in the Western Hemisphere. Amid the extreme violence of the storm, scientists observed something new: a downward beam of positrons, the antimatter counterpart of electrons, creating a burst of powerful gamma-rays and x-rays.

Detected by an instrument aboard NOAA's Hurricane Hunter aircraft, which flew through the eyewall of the storm at its peak intensity, the positron beam was not a surprise to the UC Santa Cruz scientists who built the instrument. But it was the first time anyone has observed this phenomenon.

According to David Smith, a professor of physics at UC Santa Cruz, the positron beam was the downward component of an upward terrestrial gamma-ray flash that sent a short blast of radiation into space above the storm. Terrestrial gamma-ray flashes (TGFs) were first seen in 1994 by space-based gamma-ray detectors. They occur in conjunction with lightning and have now been observed thousands of times by orbiting satellites. A reverse positron beam was predicted by theoretical models of TGFs, but had never been detected.

"This is the first confirmation of that theoretical prediction, and it shows that TGFs are piercing the atmosphere from top to bottom with high-energy radiation," Smith said. "This event could have been detected from space, like almost all the other reported TGFs, as an upward beam caused by an avalanche of electrons. We saw it from below because of a beam of antimatter (positrons) sent in the opposite direction."

One unexpected implication of the study, published May 17 in the Journal of Geophysical Research: Atmospheres, is that many TGFs could be detected via the reverse positron beam using ground-based instruments at high altitudes. It's not necessary to fly into the eye of a hurricane.

"We detected it at an altitude of 2.5 kilometers, and I estimated our detectors could have seen it down to 1.5 kilometers. That's the altitude of Denver, so there are a lot of places where you could in theory see them if you had an instrument in the right place at the right time during a thunderstorm," Smith said.

Despite the confirmation of the reverse positron beam, many questions remain unresolved about the mechanisms that drive TGFs. Strong electric fields in thunderstorms can accelerate electrons to near the speed of light, and these "relativistic" electrons emit gamma-rays when they scatter off of atoms in the atmosphere. The electrons can also knock other electrons off of atoms and accelerate them to high energies, creating an avalanche of relativistic electrons. A TGF, which is an extremely bright flash of gamma-rays, requires a large number of avalanches of relativistic electrons.

"It's an extraordinary event, and we still don't understand how it gets so bright," Smith said.

The source of the positrons, however, is a well known phenomenon in physics called pair production, in which a gamma ray interacts with the nucleus of an atom to create an electron and a positron. Since they have opposite charges, they are accelerated in opposite directions by the electric field of the thunderstorm. The downward moving positrons produce x-rays and gamma-rays in their direction of travel when they collide with atomic nuclei, just like the upward moving electrons.

"What we saw in the aircraft are the gamma-rays produced by the downward positron beam," Smith said.

First author Gregory Bowers, now at Los Alamos National Laboratory, and coauthor Nicole Kelley, now at Swift Navigation, were both graduate students at UC Santa Cruz when they worked together on the instrument that made the detection. The Airborne Detector for Energetic Lightning Emissions (ADELE) mark II was designed to observe TGFs up close by measuring x-rays and gamma-rays from aircraft flown into or above thunderstorms.

Getting too close to a TGF could be hazardous, although the risk drops off rapidly with distance from the source. The gamma-ray dose at a distance of one kilometer would be negligible, Smith said. "It's hypothetically a risk, but the odds are quite small," he said. "I don't ask pilots to fly into thunderstorms, but if they're going anyway I'll put an instrument on board."

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Giant Chinese salamander is at least five distinct species, all heading toward extinction

This photograph shows one living Chinese giant salamander from Guangxi Province.

With individuals weighing in at more than 140 pounds, the critically endangered Chinese giant salamander is well known as the world's largest amphibian. But researchers reporting in the journal Current Biology on May 21 now find that those giant salamanders aren't one species, but five, and possibly as many as eight. The bad news as highlighted by another report appearing in the same issue is that all of the salamanders -- once thought to occur widely across China -- now face the imminent threat of extinction in the wild, due in no small part to demand for the amphibians as luxury food.

The discoveries highlight the importance of genetic assessments to properly identify the salamanders, the researchers say. It also suggests that the farming and release of giant salamanders back into the wild without any regard for their genetic differences is putting the salamanders' already dire future at even greater risk. In fact, some of the five newly identified species may already be extinct in the wild.

"We were not surprised to discover more than one species, as an earlier study suggested, but the extent of diversity -- perhaps up to eight species -- uncovered by the analyses sat us back in our chairs," says Jing Che from the Kunming Institute of Zoology, Chinese Academy of Sciences. "This was not expected."

"The overexploitation of these incredible animals for human consumption has had a catastrophic effect on their numbers in the wild over an amazingly short time span," adds Samuel Turvey, from ZSL (Zoological Society of London. "Unless coordinated conservation measures are put in place as a matter of urgency, the future of the world's largest amphibian is in serious jeopardy."

The researchers were surprised to learn just how much movement of salamanders has already occurred due to human intervention. Salamander farms have sought to "maximize variation" by exchanging salamanders from distant areas, without realizing they are in fact distinct species, Che explains. As a result, she says, wild populations may now be at risk of becoming locally maladapted due to hybridization across species boundaries.

The researchers including Ya-Ping Zhang and Robert Murphy suspected Chinese giant salamanders might represent distinct species despite their similar appearances. That's because the salamanders inhabit three primary rivers in China, and several smaller ones, they explain. Each runs independently to sea.

Given that giant salamanders can't move across the land, they suspected that salamanders living in different river systems might have had opportunity to diverge over time into what should now be recognized as distinct species. And, indeed, that's exactly what the genetic evidence now suggests.

In the second study, Turvey and colleagues conducted field surveys and interviews from 2013 and 2016, in an effort that was possibly the largest wildlife survey ever conducted in China. The data revealed that populations of this once-widespread species are now critically depleted or extirpated across all surveyed areas of their range, and illegal poaching is widespread. The researchers were unable to confirm survival of wild salamanders at any survey site.

While the harvesting of wild salamanders is already prohibited, the findings show that farming practices and existing conservation activities that treat all salamander populations as a single species are potentially doing great damage, the researchers say.

"Conservation strategies for the Chinese giant salamander require urgent updating," Che says. She says it is especially critical to reconsider the design of reserves to protect the salamanders and an effort that has already released thousands of farm-started baby salamanders back into the wild.

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First interstellar immigrant discovered in the solar system

This is an image of stellar nursery NGC 604 (NASA/HST), where star systems are closely packed and asteroid exchange is thought to be possible. Asteroid (514107) 2015 BZ 509 emigrated from its parent star and settled around the Sun in a similar environment.

A new study has discovered the first known permanent immigrant to our Solar System. The asteroid, currently nestling in Jupiter's orbit, is the first known asteroid to have been captured from another star system. The work is published in Monthly Notices of the Royal Astronomical Society: Letters.

The object known as 'Oumuamua was the last interstellar interloper to hit the headlines in 2017. However it was just a tourist passing through, whereas this former exo-asteroid - given the catchy name (514107) 2015 BZ509 - is a long-term resident.

All of the planets in our Solar System, and the vast majority of other objects as well, travel around the Sun in the same direction. However 2015 BZ509 is different - it moves in the opposite direction in what is known as a 'retrograde' orbit.

"How the asteroid came to move in this way while sharing Jupiter's orbit has until now been a mystery," explains Dr Fathi Namouni, lead author of the study. "If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them."

However the team ran simulations to trace the location of 2015 BZ509 right back to the birth of our Solar System, 4.5 billion years ago when the era of planet formation ended. These show that 2015 BZ509 has always moved in this way, and so could not have been there originally and must have been captured from another system.

"Asteroid immigration from other star systems occurs because the Sun initially formed in a tightly-packed star cluster, where every star had its own system of planets and asteroids," comments Dr Helena Morais, the other member of the team.

"The close proximity of the stars, aided by the gravitational forces of the planets, help these systems attract, remove and capture asteroids from one another."

The discovery of the first permanent asteroid immigrant in the Solar System has important implications for the open problems of planet formation, solar system evolution, and possibly the origin of life itself.

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Genome structure of dinosaurs discovered by bird-turtle comparisons

This is an Apalone spinifera spiny softshell turtle hatchling.

A discovery by scientists at the University of Kent has provided significant insight into the overall genome structure of dinosaurs.

By comparing the genomes of different species, chiefly birds and turtles, the Kent team were able to determine how the overall genome structure (i.e. the chromosomes) of many people's favourite dinosaur species -- like Velociraptor or Tyrannosaurus -- might have looked through a microscope.

The research was carried out in the laboratory of Professor Darren Griffin, of the University's School of Biosciences, and is now published in the journal Nature Communications. It involved extrapolating the likely genome structure of a shared common ancestor of birds and turtles that lived around 260 million years ago -- 20 million years before the dinosaurs first emerged.

Dr Becky O'Connor, senior postdoctoral researcher and co-author of the Nature Communications paper, then traced how chromosomes changed over evolutionary time from a reptile ancestor to the present day.

The team found that, although the individual chromosomes rearranged their genes internally, this did not occur much at all between the chromosomes -- what the scientists describe as 'a significant discovery'.

Birds (which are themselves living dinosaurs) have a lot of chromosomes compared to most other species and that is possibly one of the reasons why they are so diverse. This research suggests that the pattern of chromosomes (karyotype) seen in early emerging dinosaurs and later theropods is similar to that of most birds and, again, may help explain their great diversity.

The new discovery suggests that, had scientists had the opportunity to make a chromosome preparation from a theropod dinosaur, it might have looked very similar to that of a modern-day ostrich, duck or chicken.

One of the key pieces of biotechnology that made it possible was the development of a set of fluorescent probes derived from birds that worked well on the chromosomes of turtles.

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Annotation tool provides step toward understanding links between disease, mutant RNA

bpRNA.

Researchers at Oregon State University have developed a computer program that represents a key step toward better understanding the connections between mutant genetic material and disease.

Known as bpRNA, the software is a big-data annotation tool for secondary structures in ribonucleic acids.

"It's capable of parsing RNA structures, including complex pseudoknot-containing RNAs, so you end up with an objective, precise, easily-interpretable description of all loops, stems and pseudoknots," said corresponding author David Hendrix. "You also get the positions, sequence and flanking base pairs of each structural feature, which enables us to study RNA structure en masse at a large scale."

RNA works with DNA, the other nucleic acid -- so named because they were first discovered in the cell nuclei of living things -- to produce the proteins needed throughout the body. DNA contains a person's hereditary information, and RNA delivers the information's coded instructions to the protein-manufacturing sites within the cells. Many RNA molecules do not encode a protein, and these are known as noncoding RNAs.

"There are plenty of examples of disease-associated mutations in noncoding RNAs that probably affect their structure, and in order to statistically analyze why those mutations are linked to disease we have to automate the analysis of RNA structure," said Hendrix, assistant professor of biochemistry and biophysics in the College of Science. "RNA is one of the fundamental, essential molecules for life, and we need to understand RNAs' structure to understand how they function."

Secondary structures are the base-pairing interactions within a single nucleic acid polymer or between two polymers. DNA has mainly fully base-paired double helices, but RNA is single stranded and can form complicated interactions.

Hendrix says bpRNA, presented this month in a paper in Nucleic Acids Research, features the largest and most detailed database to date of secondary RNA structures.

"To be fair it's a meta-database, but our special sauce is the tool to annotate everything," said Hendrix, who is also an assistant professor in the OSU College of Engineering. "Before there was no way of saying where all the structural features were in an automated way. We provide a color-coded map of where everything is. These annotations will enable us to identify statistical trends that may shed light on RNA structure formation and may open the door for machine learning algorithms to predict secondary RNA structure in ways that haven't been possible."

Researchers have successfully tested the tool on more than 100,000 structures, "many of which are very complex, with lots of complex pseudoknots."

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A new map for a birthplace of stars

Gas in the Orion A cloud star-forming region. Each of the three colors (red, green and blue) represents a different velocity range.

A Yale-led research group has created the most detailed maps yet of a vast seedbed of stars similar to Earth's Sun.

The maps provide unprecedented detail of the structure of the Orion A molecular cloud, the closest star-forming region of high-mass stars. Orion A hosts a variety of star-forming environments, including dense star clusters similar to the one where Earth's Sun is believed to have formed.

"Our maps probe a wide range of physical scales needed to study how stars form in molecular clouds, and how young stars impact their parent cloud," said Yale postdoctoral associate Shuo Kong, first author of a study about the group's research that appears in the Astrophysical Journal Supplement.

The research team includes astronomers from institutions in the U.S., Chile, Japan, France, Germany, Spain, and the U.K. The team's principal investigators are Yale astronomy professor Héctor G. Arce, ALMA Observatory scientist John Carpenter, and Caltech astronomy professor Anneila Sargent.

Kong said the team constructed its maps of the Orion A cloud by combining data from a single-dish telescope and an interferometer. The Yale Center for Research Computing assisted in handling the large dataset and producing the images.

The dataset and maps are collectively known as the CARMA-NRO Orion Survey. The name refers to the Combined Array for Research in Millimeter Astronomy (CARMA), an interferometer that was located in California, and the Nobeyama Radio Observatory (NRO) telescope, in Japan.

"Our survey is a unique combination of data from two very different telescopes," said Yale graduate student Jesse Feddersen, a co-author of the study. "We have combined the zoom of CARMA with the wide-angle of NRO to simultaneously capture the details of individual forming stars and the overall shape and motions of the giant molecular cloud."

In addition, the maps will help researchers calibrate star formation models for extragalactic studies. "The data we provide here will benefit research on a broad range of evolutionary stages of the star formation process and on the environment stars form," Arce said.

Yale graduate student María José Maureira is also a co-author of the study.

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