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Australian Stinging Trees Make Spider- and Cone Snail-Like Venom | Biology - Sci-News.com
A team of scientists from the University of Queensland and King’s College London has found that the venom of Australian Dendrocnide trees contains previously unidentified neurotoxic peptides and that the 3D structure of these pain-inducing peptides is reminis…
A team of scientists from the University of Queensland and Kings College London has found that the venom of Australian Dendrocnide trees contains previously unidentified neurotoxic peptides and that the 3D structure of these pain-inducing peptides is reminiscent of spider and cone snail venoms targeting the same pain receptors, thus representing a remarkable case of inter-kingdom convergent evolution of animal and plant venoms. Stinging nettles of the genus Dendrocnide produce potent neurotoxins: (A) sign at a North Queensland National Park advising caution around stinging trees; (B) Dendrocnide excelsa petioles are covered in stinging hairs; (C) scanning electron micrograph of trichome structure on the leaf of Dendrocnide moroides; (D-G) cutaneous reaction resulting from an accidental sting with Dendrocnide moroides documented with an iPhone XR and NEC G120W2 thermal imager, illustrating almost immediate local piloerection (arrowheads in D), development of wheals where stinging hairs penetrate the skin (arrows in E), as well as a long-lasting axon reflex erythema (arrows in F and G) and associated local increase in skin temperature (degrees Celsius); (H) HPLC chromatogram of trichome extract from Dendrocnide excelsa; diamonds indicate nocifensive responses elicited by intraplantar administration of individual fractions in vivo in C57BL6/J mice, with a single late-eluting peak identified as the main pain-causing fraction. Image credit: Irina Vetter, Thomas Durek & Darren Brown, University of Queensland. Australia notoriously harbors some of the worlds most venomous animals, but although less well known, its venomous flora is equally remarkable. The giant stinging tree (Dendrocnide excelsa) reigns superlative in size, with some specimens growing to 35 m (115 feet) tall along the slopes and gullies of eastern Australian rainforests. However, these members of the family Urticaceae are far more than oversized nettles. Of the six species in the genus Dendrocnide native to the subtropical and tropical forests of Eastern Australia, the giant stinging tree and the mulberry-like stinging tree (Dendrocnide moroides) are particularly notorious for producing painful stings, which can cause symptoms that last for days or weeks in extreme cases. Like other stinging plants such as nettles, the giant stinging tree is covered in needle-like appendages called trichomes that are around five millimeters in length — the trichomes look like fine hairs, but actually act like hypodermic needles that inject toxins when they make contact with skin, said Dr. Irina Vetter, a researcher in the Institute for Molecular Bioscience and the School of Pharmacy at the University of Queensland. Small molecules in the trichomes such as histamine, acetylcholine and formic acid have been previously tested, but injecting these did not cause the severe and long-lasting pain of the stinging tree, suggesting that there was an unidentified neurotoxin to be found. We were interested in finding out if there were any neurotoxins that could explain these symptoms, and why the Gympie-Gympie can cause such long-lasting pain, Dr. Vetter said. The scientists found a completely new class of neurotoxin miniproteins that they termed gympietides, after the Indigenous name for the plant. Although they come from a plant, the gympietides are similar to spider and cone snail toxins in the way they fold into their 3D molecular structures and target the same pain receptors — this arguably makes the Gympie-Gympie tree a truly venomous plant, Dr. Vetter said. The long-lasting pain from the stinging tree may be explained by the gympietides permanently changing the sodium channels in the sensory neurons, not due to the fine hairs getting stuck in the skin. By understanding how this toxin works, we hope to provide better treatment to those who have been stung by the plant, to ease or eliminate the pain. We can also potentially use the gympietides as scaffolds for new therapeutics for pain relief. The findings were published online in the journal Science Advances. _____ Edward K. Gilding et al. 2020. Neurotoxic peptides from the venom of the giant Australian stinging tree. Science Advances 6 (38): eabb8828; doi: 10.1126/sciadv.abb8828
Paleontologist Redescribes Enigmatic Armored Dinosaur from Jurassic Period | Paleontology - Sci-News.com
Scelidosaurus harrisonii, an armored dinosaur that lived around 193 million years ago (Early Jurassic epoch), has been redescribed from a near-complete skeleton discovered over 160 years ago in England.
Scelidosaurus harrisonii, an armored dinosaur that lived around 193 million years ago (Early Jurassic epoch), has been redescribed from a near-complete skeleton discovered over 160 years ago in England. Scelidosaurus harrisonii. Image credit: John Sibbick. Scelidosaurus harrisonii is an early armored ornithischian dinosaur whose remains have, to date, only been recovered from a paleontological site on the south coast of Dorset, England. This dinosaur has been known since 1859, but only on the basis of a partial description found in two short articles published in the early 1860s by Richard Owen from the British Museum in London. The original material, discovered in 1858, comprised the majority of the skull and its associated postcranial skeleton, and represents the first ever, more or less complete dinosaur discovered. Over the past three years, University of Cambridge paleontologist David Norman has devoted much of his time to preparing a detailed description and biological analysis of Scelidosaurus harrisonii, completing a project more than 150 years in the making. Scelidosaurus harrisonii represents a species that appeared at, or close to, the evolutionary birth of the Ornithischia, Dr. Norman said. Given that context, what was actually known of Scelidosaurus harrisonii? The answer: remarkably little! Nobody knew that the skull had horns on its back edge. It also had several bones that have never before been recognized in any other dinosaur, he added. It is also clear from the rough texturing of the skull bones that it was, in life, covered by hardened horny scutes — a little bit like the scutes plastered over the surface of the skulls of living turtles. Its entire body was protected by skin that anchored an array of stud-like bony spikes and plates. Scelidosaurus harrisonii had been seen for many decades as an early member of the group that included the stegosaurs and ankylosaurs, but that was based on a poor understanding of its anatomy. Now it seems that Scelidosaurus harrisonii is an ancestor of the ankylosaurs alone. It is unfortunate that such an important dinosaur, discovered at such a critical time in the early study of dinosaurs, was never properly described, Dr. Norman said. It has now been described in detail and provides many new and unexpected insights concerning the biology of early dinosaurs and their underlying relationships. The results were published in a series of four papers in the Zoological Journal of the Linnean Society of London. _____ David B. Norman. 2020. Scelidosaurus harrisonii from the Early Jurassic of Dorset, England: cranial anatomy. Zoological Journal of the Linnean Society 188 (1): 1-81; doi: 10.1093/zoolinnean/zlz074 David B. Norman. 2020. Scelidosaurus harrisonii from the Early Jurassic of Dorset, England: postcranial skeleton. Zoological Journal of the Linnean Society 189 (1): 47-157; doi: 10.1093/zoolinnean/zlz078 David B. Norman. 2020. Scelidosaurus harrisonii from the Early Jurassic of Dorset, England: the dermal skeleton. Zoological Journal of the Linnean Society 190 (1): 1-53; doi: 10.1093/zoolinnean/zlz085 David B. Norman. Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society, publihsed online August 18, 2020; doi: 10.1093/zoolinnean/zlaa061
Chandra Spots High-Velocity Knots of Stellar Debris in Kepler's Supernova Remnant | Astronomy - Sci-News.com
New images from NASA’s Chandra X-ray Observatory show small knots of metal-rich debris in the remnant of Kepler’s supernova, also known as SN 1604, are moving up to 37 million km per hour (23 million mph).
New images from NASAs Chandra X-ray Observatory show small knots of metal-rich debris in the remnant of Keplers supernova, also known as SN 1604, are moving up to 37 million km per hour (23 million mph). These are extremely high speeds for an explosion that happened over 400 years ago as seen from Earth. The Keplers supernova remnant. Image credit: NASA / CXC / University of Texas at Arlington / M. Millard et al. The Kepler supernova remnant is the debris from a detonated star that is located about 20,000 light years away in the Milky Way Galaxy. In 1604, early astronomers, including Johannes Kepler who became the objects namesake, saw the supernova explosion that destroyed the star. Astronomers now know that Keplers supernova remnant is the aftermath of a so-called Type Ia supernova, where a white dwarf exceeds a critical mass limit after interacting with a companion star and undergoes a thermonuclear explosion that shatters the white dwarf and launches stellar debris outward. In the new study, a team of astronomers from the United States, Spain and Japan estimated the speeds of 15 small, metal-rich debris knots in the supernova remnant. To do this, the researchers analyzed X-ray spectra obtained by NASAs Chandra X-ray Observatory in 2016. By comparing the wavelengths of features in the X-ray spectrum with lab values and using the Doppler effect, they measured the speed of each knot along the line of sight from Chandra to the remnant. They also used Chandra images obtained in 2000, 2004, 2006 and 2014 to detect changes in position of the knots and measure their speed perpendicular to our line of sight. These two measurements combined to give an estimate of each knots true speed in 3D space. The fastest knot was measured to have a speed of 37 million km per hour (23 million mph), the highest speed ever detected of supernova remnant debris in X-rays. The average speed of the knots is about 16 million km per hour (10 million mph), and the blast wave is expanding at about 24 million km per hour (15 million mph). These results independently confirm the 2017 discovery of knots traveling at speeds more than 32 million km per hour (20 million mph) in the Kepler supernova remnant. The high speeds in Kepler are similar to those scientists have seen in optical observations of supernova explosions in other galaxies only days or weeks after the explosion, well before a supernova remnant forms decades later. This comparison implies that some knots in Kepler have hardly been slowed down by collisions with material surrounding the remnant in the approximately 400 years since the explosion. Based on the Chandra spectra, eight of the 15 knots are definitely moving away from Earth, but only two are confirmed to be moving towards it. This asymmetry in the motion of the knots implies that the debris may not be symmetric along our line of sight, but more knots need to be studied to confirm this result. The four knots with the highest total speeds are all located along a horizontal band of bright X-ray emission. These knots are all moving in a similar direction and have similar amounts of heavier elements such as silicon, suggesting that the matter in all of these knots originated from the same layer of the exploded white dwarf. One of the other fastest moving knots is located in the ear of the right side of the remnant, supporting the intriguing idea that the 3D shape of the debris is more like a football than a uniform sphere. The explanation for the high-speed material is unclear. Some astronomers have suggested that the Kepler supernova remnant is from an unusually bright Type Ia, which might explain the fast-moving material. It is also possible that the immediate environment around the remnant is itself clumpy, which could allow some of the debris to tunnel through regions of low density and avoid being decelerated very much. The teams paper was published in the Astrophysical Journal. _____ Matthew J. Millard et al. 2020. An Ejecta Kinematics Study of Keplers Supernova Remnant with High-resolution Chandra HETG Spectroscopy. ApJ 893, 98; doi: 10.3847/1538-4357/ab7db1
Giant Wombat-Like Marsupials Roamed Australia 25 Million Years Ago | Paleontology - Sci-News.com
Paleontologists have identified a giant wombat-like marsupial that lived 25 million years ago (Oligocene epoch) in what is now Australia.
Paleontologists have identified a giant wombat-like marsupial that lived 25 million years ago (Oligocene epoch) in what is now Australia. Named Mukupirna nambensis, the prehistoric creature was at least five times larger than living wombats and so different that the researchers have had to create a new family to accommodate it. An artists impression of Mukupirna nambensis living in central Australia that was much greener 25 million years ago. Image credit: Peter Schouten. The fossilized remains of Mukupirna nambensis — a partial skull and most of the skeleton — were found in 1973 in the clay floor of Lake Pinpa in northeastern South Australia by an expedition led by Dr. Richard Tedford from the American Museum of Natural History. It was an extremely serendipitous discovery because in most years the surface of this dry lake is covered by sands blown or washed in from the surrounding hills, said Professor Mike Archer, a scientist in the PANGEA Research Centre at the University of New South Wales. But because of rare environmental conditions prior to our arrival that year, the fossil-rich clay deposits were fully exposed to view. And this unexpected view was breathtaking. On the surface, and just below we found skulls, teeth, bones and in some cases, articulated skeletons of many new and exotic kinds of mammals. As well, there were the teeth of extinct lungfish, skeletons of bony fish and the bones of many kinds of water birds including flamingos and ducks. These animals ranged from tiny carnivorous marsupials about the size of a mouse right up to Mukupirna nambensis which was similar in size to a living black bear. It was an amazingly rich fossil deposit full of extinct animals that wed never seen before. Mukupirna nambensis weighed about between 143 and 171kg, similar in size to a black bear, and that it was probably a strong digger. An analysis of evolutionary relationships shows that the ancient animal is most closely related to wombats, but it has several unique features. Mukupirna nambensis clearly was an impressive, powerful beast, at least three times larger than modern wombats, said Dr. Robin Beck, a researcher at the University of Salford. It probably lived in an open forest environment without grasses, and developed teeth that would have allowed it to feed on sedges, roots, and tubers that it could have dug up with its powerful front legs. Mukupirna nambensis reveals a fascinating mix of characteristics and provides evidence of a close link between wombats and an extinct group of marsupials called wynyardiids, said Dr. Pip Brewer, a scientist in the Department of Earth Sciences at the Natural History Museum, London. It suggests that adaptations for digging for food may have existed in the very earliest members of the wombat family and likely led to their eventual survival to the present day. Although suggested previously, it had not been possible to test this, as the oldest fossil wombats discovered are only known from teeth and a few skull fragments. The team looked at how body size has evolved in vombatiforms, which is the group that includes Mukupirna nambensis, wombats, koalas and their fossil relatives, and showed that body weights of 100 kg or more evolved at least six times over the last 25 million years. The largest known vombatifom was Diprotodon, which weighed over 2 tons and survived until approximately 50,000 years ago. Mukupirna nambensis is one of the best-preserved marsupials we know of this age from Australia, Dr. Beck said. It tells us a lot about the evolution of wombats, koalas and their relatives. It is remarkable for its large size — this was clearly an impressive, powerful beast. The description of this new family adds a huge new piece to the puzzle about the diversity of ancient, and often seriously strange marsupials that preceded those that rule the continent today, said Dr. Julien Louys, a researcher in the Australian Research Centre for Human Evolution at Griffith University. The study was published in the journal Scientific Reports. _____ R.M.D. Beck et al. 2020. A new family of diprotodontian marsupials from the latest Oligocene of Australia and the evolution of wombats, koalas, and their relatives (Vombatiformes). Sci Rep 10, 9741; doi: 10.1038/s41598-020-66425-8
Researchers Confirm Existence of Elusive Phase of Liquid Crystals | Physics - Sci-News.com
A team of scientists from the University of Colorado Boulder and the University of Utah has confirmed the existence of a ferroelectric nematic phase of liquid crystal first proposed more than 100 years ago.
A team of scientists from the University of Colorado Boulder and the University of Utah has confirmed the existence of a ferroelectric nematic phase of liquid crystal first proposed more than 100 years ago. View of a new phase of liquid crystal as seen under the microscope. Image credit: Chen et al, doi: 10.1073/pnas.2002290117. Nematic liquid crystals have been a hot topic in materials research since the 1970s. These materials exhibit a curious mix of fluid- and solid-like behaviors, which allow them to control light. Engineers have used them extensively to make the liquid crystal displays. Think of nematic liquid crystals like dropping a handful of pins on a table. The pins in this case are rod-shaped molecules that are polar. In a traditional nematic liquid crystal, half of the pins point left and the other half point right, with the direction chosen at random. A ferroelectric nematic liquid crystal phase, however, is much more disciplined. In such a liquid crystal, patches or domains form in the sample in which the molecules all point in the same direction, either right or left. In physics parlance, these materials have polar ordering. Our discovery of one such liquid crystal could open up a wealth of technological innovations — from new types of display screens to reimagined computer memory, said University of Colorado Boulders Professor Noel Clark. Nobel Laureates Peter Debye and Max Born first suggested in the 1910s that, if you designed a liquid crystal correctly, its molecules could spontaneously fall into a polar ordered state. Not long after that, researchers began to discover solid crystals that did something similar: their molecules pointed in uniform directions. They could also be reversed, flipping from right to left or vice versa under an applied electric field. These solid crystals were called ferroelectrics. Professor Clark and colleagues discovered that the liquid crystal phase of 4-[(4-nitrophenoxy)carbonyl]phenyl2,4-dimethoxybenzoate (RM734), an organic molecule created by University of York scientists in 2017, was 100 to 1,000 times more responsive to electric fields than the usual nematic liquid crystals. This suggested that the molecules that make up the liquid crystal demonstrated strong polar order. When the molecules are all pointing to the left, and they all see a field that says, go right, the response is dramatic, Professor Clark said. The scientists also discovered that distinct domains seemed to form spontaneously in the liquid crystal when it cooled from higher temperature. There were, in other words, patches within their sample in which the molecules seemed to be aligned. That confirmed that this phase was, indeed, a ferroelectric nematic fluid, Professor Clark said. That alignment was also more uniform than the team was expecting. Entropy reigns in a fluid. Everything is wiggling around, so we expected a lot of disorder, said University of Colorado Boulders Joe MacLennan. When we examined how well aligned the molecules were inside a single domain, we were stunned by the result. The molecules were nearly all pointing in the same direction. The study was published in the Proceedings of the National Academy of Sciences. _____ Xi Chen et al. First-principles experimental demonstration of ferroelectricity in a thermotropic nematic liquid crystal: Polar domains and striking electro-optics. PNAS, published online June 10, 2020; doi: 10.1073/pnas.2002290117 This article is based on text provided by the University of Colorado at Boulder.
Bumblebees Bite Leaves of Flowerless Plants to Stimulate Earlier Flowering | Biology - Sci-News.com
A team of researchers from ETH Zürich and the Universite Paris-Saclay made observations suggesting that bumblebees have strategies to cope with irregular seasonal flowering: when faced with a shortage of pollen, bumblebees actively damaged plant leaves and th…
Bumblebees rely heavily on pollen resources for essential nutrients as they build their summer colonies. Therefore, annual differences in the availability of these resources must simply be tolerated, but a team of researchers from ETH Zürich and the Universite Paris-Saclay made observations suggesting that bumblebees have strategies to cope with irregular seasonal flowering: when faced with a shortage of pollen, bumblebees actively damaged plant leaves and this behavior resulted in earlier flowering by as much as 30 days. Bumblebee workers facing pollen scarcity use their proboscises and mandibles to cut distinctively shaped holes in plant leaves, with each damage event taking only a few seconds. Image credit: Hannier Pulido / ETH Zurich. Previous work has shown that various kinds of stress can induce plants to flower, but the role of bee-inflicted damage in accelerating flower production was unexpected, said co-lead author Professor Mark Mescher, a researcher in the Department of Environmental Systems Sciences at ETH Zürich. Initial observations with four plant species revealed that bumblebee workers use their proboscises and mandibles to cut holes in plant leaves. However, Professor Mescher and his colleagues saw no clear evidence that bumblebees were actively feeding on leaves or transporting leaf material back to the hive. The scientists then conducted several lab experiments and outdoor studies using commercially available bumblebee colonies and a variety of plant species. They were able to show that the bumblebees propensity to damage leaves has a strong correlation with the amount of pollen they can obtain — the bees damage leaves much more frequently when there is little or no pollen available to them, They also found that damage inflicted on plant leaves had dramatic effects on flowering time in two different plant species: tomato plants subjected to bumblebee biting flowered up to 30 days earlier than those that hadnt been targeted, while mustard plants flowered about 14 days earlier when damaged by the bees. The bee damage had a dramatic influence on the flowering of the plants — one that has never been described before, said co-lead author Professor Consuelo De Moraes, also from the Department of Environmental Systems Sciences at ETH Zürich. The developmental stage of the plant when it is bitten by bumblebees may influence the degree to which flowering is accelerated. The authors also tried to manually replicate the damage patterns caused by bumblebees to see if they could reproduce the effect on flowering time. But, while this manipulation did lead to somewhat earlier flowering in both plant species, the effect was not nearly as strong as that caused by the bees themselves. Chemical or other cue may also be involved. Either that or our manual imitation of the damage wasnt accurate enough, Professor De Moraes said. Bumblebees may have found an effective method of mitigating local shortages of pollen, she added. Our open fields are abuzz with other pollinators, too, which may also benefit from the bumblebees efforts. The findings were published in the journal Science. _____ Foteini G. Pashalidou et al. 2020. Bumble bees damage plant leaves and accelerate flower production when pollen is scarce. Science 368 (6493): 881-884; doi: 10.1126/science.aay0496