Adams rib revisited Evolutionary divergence of mammalian sex chromosomes

first_img The increased imbalance of X/Y chromosomal loci led to the emergence of loci-specific X chromosome inactivation, which has been seen as compensating for differential gene dosage (the number of copies of a given gene present in a cell or nucleus) by making expression of X-linked genes similar in males and females. Recently, using RNA sequencing, or RNA-seq, data (more precise than previously-analyzed microarray data), scientists in the Laboratoire de Biométrie et Biologie Évolutive, Université Lyon, Centre National de la Recherche Scientifique, in Villeurbanne, France, found support for the hypothesis that XCI acts as a dosage-compensation mechanism. At the same time, the scientists explored the contribution of dosage-sensitive genes to phenotype expression in X aneuploidy – a condition, relatively common in humans, in which one or more extra or missing chromosomes leads to an unbalanced chromosome complement, resulting in conditions such as Turner (X0) and Klinefelter (XXY) syndromes. Associate Professor Gabriel A. B. Marais, PhD student Eugénie Pessia and other researchers faced a number of challenges in designing and implementing research to determine how and why female somatic X-chromosome inactivation evolved in mammals – especially given that it has been poorly understood. “When X-chromosome inactivation, or XCI, was first described in the 1960s, Susumu Ohno suggested that XCI evolved as part of a dosage compensation mechanism involving X chromosome hyperexpression in both sexes coupled with inactivation of one of the X chromosomes in females,” Marais tells Phys.org. “However, the X hyperexpression part of Ohno’s scenario has remained completely speculative for a very long time. Only recently, several studies have tried to compare the global X versus autosomal expression – the so-called X/A expression ratio – using microarray or RNA-seq data. Some found an X/A close to 1, others close to 0.5 – but the most recent studies from 2011 found a ratio of 0.7, which was difficult to interpret. We thought that maybe only some of X-linked genes need to be hypertranscribed and dosage-compensated, which would explain the X/A of 0.7 when all X-linked genes – that is, some with an X/A of 1 and some with an X/A of 0.5 – are analyzed together. We thought that it would make perfect sense if only the dosage-sensitive genes on the X chromosome would have an X/A of 1, as they’re the ones that need a precise dosage.” Explore further X expression and autosomal expression in large protein complexes versus others. For each tissue, the ratio of the medians of X gene expression of large complexes and of X gene expression of other protein complexes was computed (the XL/XO ratio, in red). The ratio of the medians of autosomal gene expression of large complexes and of autosomal gene expression of other protein complexes—the AL/AO ratio (blue)—was computed similarly. The two green dashed lines indicate expectations with a twofold increase of expression (ratio of 2) and without any change in expression (ratio of 1). Image Copyright © PNAS, doi: 10.1073/pnas.1116763109 Citation: Adam’s rib, revisited: Evolutionary divergence of mammalian sex chromosomes (2012, April 18) retrieved 18 August 2019 from https://phys.org/news/2012-04-adam-rib-revisited-evolutionary-divergence.html The research team addressed these issues by studying gene expression of dosage-sensitive genes on the X chromosome – but since those are not very well known. “Based on studies in plants, yeasts and also in humans, we thought we should focus on protein-complex genes,” Marais explains. “Protein complexes require a precise stochiometry to be functional, which means that if one protein is much more abundant than the other proteins of the complex, it is likely to be nonfunctional, which may be harmful for the cell.” They used the data on human complexes from the HPRD database to get our list of protein-complex genes on the X chromosome.”For large complexes,” Marais continues, “we found that the expression levels estimated by RNA-seq are similar for X-linked and autosomal genes of a same complex. This is quite striking because both in male and female, only one X is present or expressed, whereas both autosomes are expressed. The X-linked genes have only one expressed copy and the autosomal two, so the expression of the X-linked genes should be half that of the autosomal ones, but we found it to be the same, which means the X-linked genes are hyperexpressed. How this hyperexpression is achieved remains an open question, but recent data in mice suggests that RNA polymerase II could be more abundant on these X-linked genes, probably because of epigenetic marks.”Looking ahead, Marais notes, “We’d like to study the other dosage-sensitive genes on the X chromosome, as we know that protein-complex genes are not the only ones. Genes involved in regulatory networks are probably dosage-sensitive. However, we need better characterization of these networks in humans before extending our analysis to these other dosage-sensitive genes.”Marais adds that the team would like to understand how XCI originated. “We showed that XCI is part of a dosage compensation mechanism for dosage-sensitive X-linked genes, because XCI downregulates their expression to get a balanced X and autosomal expression, and thereby avoid an X/A of 2, in females. However,” he acknowledges, “our study does not provide insights on how XCI evolved in the first place. X-inactivation is found in placentals and marsupials – and in marsupials and in some tissues of some placentals, it is the paternal X that is always inactivated. David Haig has proposed that X-inactivation might originally be a form of genetic imprinting, which evolved because of parental conflicts. We’d like to test this idea.”Marais also points out that it might well be possible to transition to in silico modeling. “Actually, there’s very little theoretical work on the evolution of dosage compensation. The hypothesis proposed by David Haig has not been modeled at all,” he notes, “and it would be important to show by simulation that his scenario can work.”Regarding research, technology and applications might benefit from their findings, Marais notes that in humans, most aneuploidies (aberrant number of chromosomes) are lethal. “Trisomy 21 is an exception, but there are strong effects on the phenotype known as Down syndrome. The X chromosome is another exception, and X aneuploidies have surprisingly mild effects given the size of this chromosome and the number of genes it contains compared to chromosome 21 – one of the smallest chromosomes in our genome. This is because all the supernumerary X chromosomes are inactivated by XCI, so in XXY individuals or X0 individuals, only one X is expressed just like in XX or XY individuals. However, about 15% of the genes located on the human X chromosome escape XCI, and for these ones X aneuploidies will have consequences on gene dosage. Our results suggest that the consequences will be stronger for the dosage-sensitive genes.” Marais concludes. He suggests that genes being both dosage-sensitive and XCI-escapees are probably the best candidates for underlying X aneuploidy syndromes such as Turner (X0), Klinefelter (XXY) and Triple-X. “The identification and characterization of such genes would of course help develop treatments that some patients affected by these very frequent syndromes need.” Study confirms males and females have at least one thing in common: Upregulating Xcenter_img More information: Mammalian X chromosome inactivation evolved as a dosage-compensation mechanism for dosage-sensitive genes on the X chromosome, Published online before print March 5 2012, PNAS April 3 2012 vol. 109 no. 14 5346-5351, doi: 10.1073/pnas.1116763109 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (Phys.org)—Males and females… Mars and Venus… XY and XX chromosomes—all are common memes. At the same time, the evolution of therian (placental and marsupial) sex chromosomes is less widely understood. More to the point, these arose some 150 million years ago from a pair of autosomes, or non-sex chromosomes. Having appeared, the X and Y chromosomes – both with the same ancestral genes – began diverging, with the Y chromosome evolving into a state in which (except for two small autosomal regions) it never recombines. As a result, the Y chromosome has degenerated, losing most of its genes in the process. On the other hand, the X chromosome does recombine, retains many ancestral genes – and has gained new genes, and evolved new expression patterns, as well. Copyright 2012 Phys.Org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.last_img read more

New phase of water could dominate the interiors of Uranus and Neptune

first_img Explore further Mysterious planetsAlthough superionic ice doesn’t exist under normal conditions on Earth, the high pressures and temperatures where it is thought to exist are very similar to the predicted conditions in the interiors of Uranus and Neptune. “Uranus and Neptune are called ice giants because their interiors consist primarily of water, along with ammonia and methane,” Wilson said. “Since the pressure and temperature conditions of the predicted new phase just happen to line up with the pressure and temperature conditions of the interiors of these planets, our new fcc superionic phase may very well be the single most prevalent component of these planets.”The researchers predict that understanding superionic ice—particularly the stable fcc phase—will offer insight into these ice giants.”Uranus and Neptune remain very poorly understood at this stage, and their interiors are deeply mysterious,” Wilson said. “The observations we have are very limited—every other planet in the solar system we’ve visited multiple times, but Uranus and Neptune we’ve just done brief flybys with Voyager 2. What we do know is that they have bizarre non-axisymmetric non-dipolar magnetic fields, totally unlike any other planet in our solar system. We also know that they’re extremely similar in mass, density and composition, yet somehow fundamentally different, because Neptune has a significant internal heat source and Uranus hardly emits any heat at all.”It’s possible that the predicted bcc-to-fcc phase transition may explain the planets’ unusual magnetic fields, although more research is needed in this area.”Our results imply that Uranus’s and Neptune’s interiors are a bit denser and have an electrical conductivity that is slightly reduced compared to previous models,” Militzer added.Understanding Uranus and Neptune’s interiors could have implications far beyond our solar system, as well.”One thing we’re learning from the Kepler mission is that Uranus-like or Neptune-like exoplanets are extremely common,” Wilson said. “They appear to be more common than Jupiter-like gas giants. So understanding our local ice giants is important, because they’re an archetypal example for a huge class of planets out there in the universe.” Future experimentsIn the future, the researchers plan to investigate the possible existence of a third superionic phase, as well as attempt to detect the predicted transition between the bcc and fcc phases. “Shock wave experiments combined with X-ray diffraction techniques will enable one to detect the predicted bcc-to-fcc transition,” Militzer said. “Shock waves allow one to reach megabar pressure and heat the sample to thousands of Kelvin at the same time. X-ray diffraction measurements allow one to determine whether the oxygen atoms reside on bcc or fcc positions. This leads to an obvious change in the X-ray diffraction pattern. Shock waves and X-ray diffraction have rarely been combined so far, but Dr. Jon Eggert at Lawrence Livermore National Laboratory is in the process of preparing such experiments.” Citation: New phase of water could dominate the interiors of Uranus and Neptune (2013, April 25) retrieved 18 August 2019 from https://phys.org/news/2013-04-phase-dominate-interiors-uranus-neptune.html Copyright 2013 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of Phys.org. Pounding particles to create Neptune’s water in the lab Journal information: Physical Review Letters More information: Hugh F. Wilson, et al. “Superionic to Superionic Phase Change in Water: Consequences for the Interiors of Uranus and Neptune.” PRL 110, 151102 (2013). DOI: 10.1103/PhysRevLett.110.151102 (Phys.org) —While everyone is familiar with water in the liquid, ice, and gas phases, water can also exist in many other phases over a vast range of temperature and pressure conditions. One lesser known phase of water is the superionic phase, which is considered an “ice” but exists somewhere between a solid and a liquid: while the oxygen atoms occupy fixed lattice positions as in a solid, the hydrogen atoms migrate through the lattice as in a fluid. Until now, scientists have thought that there was only one phase of superionic ice, but scientists in a new study have discovered a second phase that is more stable than the original. The new phase of superionic ice could make up a large component of the interiors of giant icy planets such as Uranus and Neptune. Phase diagram of water showing the fully fluid, solid, and superionic regimes. The superionic regime is shaded to show the transition from bcc (red) to fcc (yellow) phase stability as pressure increases. Credit: Hugh F. Wilson, et al. ©2013 American Physical Society Structure of superionic ice in (left) the bcc phase and (right) the newly discovered and more stable fcc phase. Credit: Hugh F. Wilson, et al. ©2013 American Physical Society The scientists, Hugh F. Wilson (now at the Commonwealth Scientific and Industrial Research Organisation [CSIRO] in Australia), Michael L. Wong, and Burkhard Militzer at the University of California, Berkeley, have published a paper on the new phase of superionic ice in a recent issue of Physical Review Letters. Exotic waterAs the scientists explain, water has an unusually rich phase diagram, with 15 crystalline phases observed in laboratory experiments and eight additional phases predicted theoretically. “Superionic water is a fairly exotic sort of substance,” Wilson told Phys.org. “The phases of water we’re familiar with all consist of water molecules in various arrangements, but superionic water is a non-molecular form of ice, where hydrogen atoms are shared between oxygens. It’s somewhere between a solid and a liquid—the hydrogen atoms move around freely like in a liquid, while the oxygens stay rigidly fixed in place. It would probably flow more like a liquid, though, since the planes of oxygen atoms can slide quite freely against one another, lubricated by the hydrogens.”The original phase of superionic ice, called the body centered cubic (bcc) phase, was first predicted with ab initio computer simulations in 1999 by Carlo Cavazzoni, et al. Scientists predict that the bcc phase exists at pressures in excess of 0.5 Mbar (500,000 times greater than atmospheric pressure) and temperatures of a few thousand Kelvin. The bcc phase derives its name from the fact that the oxygen atoms occupy body centered cubic lattice sites. Hints of the bcc phase’s instability have been previously observed, but the new study shows for the first time that the bcc phase is less stable than the new phase where the oxygen atoms occupy sites on a face centered cubic (fcc) lattice. The scientists predict that the fcc phase exists at pressures in excess of 1.0 Mbar, even higher than the pressure for the bcc phase. The scientists’ ab initio molecular dynamics simulations also show that the fcc phase has a higher density and lower hydrogen mobility than the bcc phase. That is, the hydrogen atoms in the fcc structure move less frequently to nearby voids between the oxygen atoms, while in the bcc structure, they migrate more freely between different sites. This difference affects the water’s thermal and electrical conductivity. In addition, the simulations show that a phase transition between the bcc and fcc phases may exist at pressures of 1.0 ± 0.5 Mbar. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Antibiotics 20 The atomic structure and mechanism of mammalian hostdefense peptides

first_imgCrystal structure and surface characteristics of the human dermcidin channel. (A) X-ray structure of the hexameric DCD channel shown in cartoon representation from the side and top (Middle and Right), and as surface representation (Left). The different orientations of the individual peptides relative to the membrane normal are marked in orange and dark blue, and termini are marked (NT, N terminus; CT, C terminus). Arrows combined with tilt angle and axes give the relative orientation. Residues involved in Zn binding are shown in stick representation and Zn ions are marked in gray. The symmetry axis of the channel is marked with C2 (for the side view) and C3 (for the top view). Two interfaces of different surface area are formed after trimerization and named IF1 and IF2. (B) Close-up into the Zn-binding site S1. Four residues (Glu5 and Asp11 from one peptide and Asp41 and His38 from the second) form each Zn-binding site. The distance between the Zn ions is marked by arrows. (C) Electrostatic surface representation of the channel with two monomers marked in ribbon representation. The channel comprises five alternating patches of elongated negative (red) and ring-like positive (blue) charge. (D) Side view of DCD (hydrophobic residues in magenta). (E) Ribbon model of DCD. The pore diameter is represented by spheres. The lateral entry points are marked with circles. (F) Hydrophilic residues on the trimeric interface (negatively charged residues in red, positively charged residues in blue, polar residues in green). Nonpolar residues are shown in white. (G) The hydrophilic channel interior. For clarity, the front dimer is omitted; colors as in F. (H) Channel radius along the pore axis. Copyright © PNAS, doi:10.1073/pnas.1214739110 Frogs skin gives researchers the hop on bacteria (Phys.org) —While the natural world is replete with compounds that form the basis of many disease-fighting pharmaceuticals, it is also the case that humans and other mammals produce their own host-defense peptide-derived broad-spectrum antibiotics to combat bacterial and fungal infections. By attacking microbial cell membranes, these peptides prevent bacteria from developing rapid antibiotic resistance. While over 1,700 of these peptides are known, the structural and mechanical aspects of their functional activity have remained an unanswered question. Recently, however, scientists at Max Planck Institute for Biophysical Chemistry, Max Planck Institute for Developmental Biology, The University of Edinburgh, and other instiutions1 determined the X-ray crystal structure as well as solid-state nuclear magnetic resonance (NMR) spectroscopy, electrophysiology, and molecular dynamic (MD) simulations of human dermcidin (DCD), revealing its mechanism at atomic scale. The researchers conclude that their results may lead to the peptide structure-based design of second-generation antibiotics. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen , Nature Prof. Kornelius Zeth spoke with Phys.org about the challenges that he, Dr. Ulrich Zachariae, Dr. Chen Song, Dr. Bert de Groot, and his other colleagues encountered in conducted their research. “For crystallography it was very difficult to find a proper peptide source. In fact, we had to use five different peptides from different companies until we found a company, Peptide 2.0 Inc., which produced the peptide in the correct way,” Zeth recalls. “However, I can’t say they’ve modified their process – and luck also a factor, as are and several parameters which are influential aside from the peptide, such as who conducts the robotic screening, local climate and so on.”Moreover, the simulations that revealed the antibiotic mechanism of human dermcidin had their own complications. “Simulations require time and experience in order to capture the correct lipidic environment,” Zeth adds. “Also, the choice of the proper MD method was critical to tracing the mechanism by which ions passed through the channel.” The simulations went on for many months, he illustrates, depending on the system studied, to get a complete picture of the membrane channels. More specifically, Song notes that the production simulations took more than a year – roughly 650 days – in real time using 48 CPUs.”Several consistency checks were carried out to ensure the validity of the MD simulations,” de Groot points out. “First, the simulation parameters and setup were carefully selected to mimic the bacterial conditions as closely as possible. Second, to ensure convergence the simulations were carried out multiple times, from different starting conditions. Third, the conductance derived from the electrophysiology simulations were directly compared to measured values, showing quantitative agreement.”Another challenge, Zeth says, was conducting electrophysiology experiments in which the scientists characterized the activity of dermcidin in membranes under various conditions. “Methods applied to solve this problem are typically based on recent developments in electrophysiology. One general problem of DCD is that the peptide is very soluble in water and does not easily enter artificial membranes.” in fact, this finding has also caused NMR problems when trying to verify the tilting of the channel in membranes as predicted by MD simulations. These studies were hampered by the small portion of the peptide that was observable in an integral membrane conformation. More information: Crystal structure and functional mechanism of a human antimicrobial membrane channel, PNAS March 19, 2013 vol. 110 no. 12 4586-4591, doi:10.1073/pnas.1214739110Related: 1Georg August University – Göttingen, University of Strasbourg, Centre National de la Recherche Scientifique, Freiburg University, University of Basque Country, Spanish Science Research Council 2Editor’s Summary: Trigger for psoriasis, Nature 4 October 2007 Discussing how their findings articulate the comprehensive mechanism for the membrane-disruptive action of this mammalian host-defense peptide at atomistic level, Zeth notes that their findings are based on the combination of several techniques. “Starting from the crystal structure,” he explains, “we modeled the ion flux, later deciding to verify the theoretical calculations and values by experimental data. We’ve also tried to model the tilting behavior seen in MD simulation by solid state NMR techniques, but this approach failed. Nevertheless, the overall picture, while incomplete, leads to many follow-up experiments and stimulates the AMP community regarding the development of new mechanistic views.” As for the conductance calculated by MD, however, researchers we were able to reproduce these values using planar lipid membrane techniques in an error range of only 20%. While their paper states that their results may form a foundation for the structure-based design of peptide antibiotics, Zeth says that this is rather difficult to judge. “In fact, he says, the German company BRAIN is trying to introduce DCD into pharmaceutical studies. However, if you look closer into the general applications of peptides as AMPs, it’s rather frustrating. To my knowledge,” Zeth acknowledges, “there are no AMP peptides sold as pharmaceuticals at the moment, although the general market of peptides – against cancer and other diseases – is still growing. The problem is the size and stability of the peptides if given orally or into the bloodstream as proteases, but. DCD is active on skin – so might be easier if it was to be introduced into creams.”Zeth then described medical properties and potential of host-defense antimicrobial peptides for comparison with traditional small-molecule antibiotics.Specificity: Rather unspecific. Gram-positives and negatives are concerned while with traditional antibiotics either Gram+/Gram- are treated.Efficacy: likely to be more efficient due to inherent molecular antibacterial propertiesSafety: Not yet determined but as these molecules come from humans they should not be toxicPost-xenotransplantation immune response: Currently unknown. The problem with antimicrobial peptides is protease-based instability in the bloodstream and stomach.Autoimmune diseases: Some peptides, such including LL-37, have severe implications in autoimmunity. In fact, the overproduction of these peptides generates a number of skin diseases, such as psoriasis. More specifically, in the case of psoriasis it seems that LL-37 overproduction can cause autoimmune diseases,2 the unresolved issue being whether the peptides are produced inside or outside the cell.In terms of next steps in their research, Zeth mentions studies of mutations in the membrane-exposed side of the channel; changing properties, such as conductivity or membrane integration, inside the membrane to; peptide translocation via membranes; and mentions post-xenotransplantation immune response as “an idea for future applications.”Zeth notes that other areas of research might benefit from their research. “Generally our study will influence the current view of peptide channels in membranes – an important field, in particular for researchers trying to enhance this domain of knowledge to improve current peptide drugs. Also, our channel study benefits MD for further use in a variety of studies on mutations and different approaches to better characterize the channel. The channel is thereby a tool,” Zeth concludes, “for testing methods and answer questions which were, so far, difficult to answer due to missing structural models.” Journal information: Proceedings of the National Academy of Sciencescenter_img Citation: Antibiotics 2.0: The atomic structure and mechanism of mammalian host-defense peptides (2013, April 30) retrieved 18 August 2019 from https://phys.org/news/2013-04-antibiotics-atomic-mechanism-mammalian-host-defense.html Play Multiion permeation mechanism across DCD driven by transmembrane electric fields present across bacterial membranes. Ions enter sideways into the pore across the lateral openings that occur at the trimeric interfaces. Anion transfer across the inner pore usually involves single ion “hopping” steps. Near the channel exit, anions accumulate to form a cluster of three to four ions. Ions exiting the channel are often observed to be translocated by multiion “knockon” effects, by which anions are transferred to the bulk solution. Copyright © PNAS, doi:10.1073/pnas.1214739110 “Peptide solubility or membrane affinity can be influenced by several parameters, such as mutations or changing membrane systems,” Zeth continues. “For NMR we’ve seen essentially all of the peptide associated with the membrane in a horizontal manner. However, we were more interested in the peptide complex inserted in the membrane, but that only occurred ten percent or less of the time.” Zeth outlines the key insights and discoveries that helped the team address these challenges. “One important factor was that this was the first structure of an anti-microbial peptide in a channel conformation,” he explains. “Another was that this peptide activity seems to be zinc-dependent – although it is not really clear what activity zinc actually causes. Also,” Zeth adds, “our model, based on the molecular dynamics of ion flow through the channel, is new and unexpected, in that lateral pore openings seem to play a more important role than do terminals.”Zeth points out that their study solved the crystal structure of an AMP (antimicrobial peptide) channel for the first time in a putative channel conformation. “This result allowed a number of follow-up experiments, in particular MD simulations without assembling a rather artificial membrane pore,” he explains. “In my opinion, our AMP structure is the first to be assembled on the basis of direct X-ray data. All other AMPs used for MD are assembled based on indirect data, and while these assemblies may be correct, their structural information cannot be compared to the quality of X-ray data. This allowed us to use a system that reflects the closest membrane-bound state.” © 2013 Phys.org. All rights reserved. Explore further Model system used in the MD simulations. (A) The initial simulation system, which contains the X-ray structure of DCD (orange and deep blue cartoon helices), the POPE/POPG (3:1) lipids bilayer (gray sticks), water box (light blue surface), Na+ (blue spheres), and Cl− (red spheres) ions. (B) The MD conformation after 100-ns simulation, which was then duplicated in the membrane normal direction to form the double-patch simulation system for the computational electrophysiology simulations (C). Copyright © PNAS, doi:10.1073/pnas.1214739110 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Study implicates global warming as a factor in increasing economic losses due

first_img Geographer says, expect weather severity to increase Explore further Citation: Study implicates global warming as a factor in increasing economic losses due to hurricanes (2015, October 20) retrieved 18 August 2019 from https://phys.org/news/2015-10-implicates-global-factor-economic-losses.html (Phys.org)—A trio of researchers affiliated with Universidad Nacional Autónoma in Mexico, and VU University in the Netherlands, has conducted a study on the source of an increase in property dollar amounts lost over the past several decades due to hurricanes and has concluded that it cannot be blamed on an increase in wealth or construction—instead, they suggest in their paper published in Nature Geoscience, that it is due to more storms, because of global warming. Stéphane Hallegatte with the Climate Change Policy Team at the World Bank, offers a News & Views piece in the same journal edition on the work done by the team, outlining the process that was used, and highlighting possible problems with the results. © 2015 Phys.org More information: Francisco Estrada et al. Economic losses from US hurricanes consistent with an influence from climate change, Nature Geoscience (2015). DOI: 10.1038/ngeo2560AbstractWarming of the climate system and its impacts on biophysical and human systems have been widely documented. The frequency and intensity of extreme weather events have also changed, but the observed increases in natural disaster losses are often thought to result solely from societal change, such as increases in exposure and vulnerability. Here we analyse the economic losses from tropical cyclones in the United States, using a regression-based approach instead of a standard normalization procedure to changes in exposure and vulnerability, to minimize the chance of introducing a spurious trend. Unlike previous studies, we use statistical models to estimate the contributions of socioeconomic factors to the observed trend in losses and we account for non-normal and nonlinear characteristics of loss data. We identify an upward trend in economic losses between 1900 and 2005 that cannot be explained by commonly used socioeconomic variables. Based on records of geophysical data, we identify an upward trend in both the number and intensity of hurricanes in the North Atlantic basin as well as in the number of loss-generating tropical cyclone records in the United States that is consistent with the smoothed global average rise in surface air temperature. We estimate that, in 2005, US$2 to US$14 billion of the recorded annual losses could be attributable to climate change, 2 to 12% of that year’s normalized losses. We suggest that damages from tropical cyclones cannot be dismissed when evaluating the current and future costs of climate change and the expected benefits of mitigation and adaptation strategies.center_img Monetary losses that come about due to natural disasters are on the rise, particularly from storms such as hurricanes—that much is clear. What is not clear is whether this trend can be blamed on changes in the weather or people building more expensive stuff in the path of such storms. Some recent studies have found that it is mostly the latter, but that, the researchers with this new effort argue, is because the approach used to reach such conclusions was flawed.The traditional way of normalizing damage from hurricanes, Hallegatte explains, involves an approach where it is assumed that an increase in damage would come about evenly with an increase in wealth—i.e. doubling wealth in an area would double the damage costs that occurred in it. But that thinking is flawed, the researchers contend, because it does not take into consideration the fact that as an area grows more wealthy, some of that money is used to prevent storm damage. They conducted their own study using a method that took such changes into account and their results showed that the economic loss increases due to hurricanes over the period 1900 to 2005 could not be solely attributed to an increase in wealth—they suggest that the other increase was due to an increased number of storms and stronger intensity (due to global warming) and further suggest that between 2 and 12 percent of losses due to such storms in the year 2005 alone (the year Katrina struck New Orleans), could be attributed to global warming.Hallegatte agrees with the approach used by the researchers but points out that the change used to normalize the data is not proven, nor is the assumption that an increase in the number of storms, or their intensity can be blamed on global warming. Hurricane Isabel (2003) as seen from orbit during Expedition 7 of the International Space Station. Credit: NASA Journal information: Nature Geoscience This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Example of microplastic pollutants disrupting predatorprey relationship found

first_img Journal information: Biology Letters Citation: Example of microplastic pollutants disrupting predator-prey relationship found (2018, November 28) retrieved 18 August 2019 from https://phys.org/news/2018-11-microplastic-pollutants-disrupting-predator-prey-relationship.html More information: Microplastic leachates impair behavioural vigilance and predator avoidance in a temperate intertidal gastropod, Biology Letters (2018). rsbl.royalsocietypublishing.or … .1098/rsbl.2018.0453 First evidence that seals can consume microplastics via their prey © 2018 Science X Network Explore furthercenter_img Credit: CC0 Public Domain A team of researchers with the French National Centre for Scientific Research has found an example of environmental microplastics disrupting a predator-prey relationship. In their paper published in the journal Biology Letters, the group describes their study of the impact of microplastic consumption on the common periwinkle and what they found. The researchers note that to date, many studies have been done to better understand what happens to living creatures when they consume microplastics—but little work has been done to better understand what happens to the relationship between predators and prey when microplastics are introduced into the environment.Periwinkles are a kind of shellfish, or more precisely, a sea snail. They spend their time perched on algae-covered rocks grazing on the algae. They are considered a keystone creature because of the role they play as prey for other creatures, mainly crabs. Periwinkles are also consumed by humans. In this new effort, the researchers wondered what might happen to periwinkles that consume algae that has itself absorbed microplastics. Prior research has shown that when algae absorb microplastics, they also absorb hazardous chemicals and metals. This is because microplastics absorb such materials from the water. When a periwinkle eats the algae, it is also eating the hazardous materials present in the algae.To find out if the heavy metals or other toxic substances eaten by the periwinkle cause disruptive changes, the researchers gathered some specimens and brought them into the lab for testing. They also collected crabs to use as predators.The researchers report that when a periwinkle that had consumed the toxic materials, it did not react in an expected way to the presence of a predator. Normally, upon spying a crab, a periwinkle will pull into its shell or try to hide to avoid capture. The periwinkles exposed to the toxic materials did not attempt to avoid capture, which suggested they had nerve damage of some sort, likely due to consumption of heavy metals.The researchers note that in their experiments, the levels of toxicity in the microplastics were equivalent to those on a typical beach, thus representing real-world conditions. The researchers suggest their findings hint at major changes happening in the marine environment due to the microplastics introduced by us humans. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

New Yorkers Call For Fair Elections

first_img Photo Credit: US Air Force by Natalie Migliore New Yorkers Call For Fair Elections Audio PlayerYour browser version does not support the audio element00:0000:0000:00Use Up/Down Arrow keys to increase or decrease volume. 8.22.19 10:29am New York State’s Public Campaign Financing Committee met for the first time Thursday. Advocates gathered outside the meeting to let the nine committee members know they’re following decisions and discussions closely. The committee was commissioned by Governor Cuomo and is tasked with deciding how much money the government can supliment campaigns, among other issues.last_img

Ni Hao Delhi

first_imgThe India China Economic and Cultural council, Delhi in cooperation with the Chinese Embassy in India, is organising a cultural evening titled India-China Cultural Extravaganza 2013. The primary aim of the event is to strengthen the bilateral cultural cooperation between the two countries. The ICEC had hosted the Chinese Spring Festival earlier this year. ICEC works closely with the Chinese Embassy in India to organize cultural festivals. This is apart from hosting business delegates and providing consultancy services to Indian and Chinese companies on matters of business. Also Read – ‘Playing Jojo was emotionally exhausting’On the cultural front, this is ICEC’s yet another effort to organise an evening to celebrate the 64th Anniversary of the National Day of the People’s Republic of China. The ICEC Council takes this opportunity to celebrate with the people of China. The Performances include Diablo Acrobatics, Changing Faces (Bian Lian), Indian Magician will Showcase Chinese Culture through his magic tricks, Rajasthani Folk Dance (Kalbelia and Bhavai), Indian and Western Fusion Music by ‘Rising India’ band and Foot JugglingThe entry to the cultural extravaganza is free. Since the number of seats is limited, the reservation would be on first come, first serve basis.last_img read more

The joy of weaving

first_imgA five- day exhibition was organised by Raj Group, a manufacturer and exporter of weaved materials, celebrating their 75th anniversary. The exhibition that started on 4 July at Stainless Gallery and displayed 18 pieces comprising of art installations, carpets, photographs and wall art. The show also featured photographs by Ajit Bhadoriya and Brahm Maira which narrated the journey of the group since the time the photographers got associated with it. The exhibition also gave a glimpse of its traditions and legacy. Also Read – ‘Playing Jojo was emotionally exhausting’‘We are extremely delighted to announce our 75 glorious years of weaving traditions this year. The works displayed are specially made for the exhibition. Designed and handcrafted within our factory premises at Panipat (Haryana), materials like wool, jute, fabric and Poly Ethylene Terephthalate (PET) have been used to make the art works’, says Ajay Nath, Managing Partner, Raj Group. Established in 1939, the group is well known for manufacturing carpets like Panja weaving and displaying an array of carpets and rugs amongst other such products.last_img read more

PM nod must to suspend babus at Centre

first_imgIAS officers working under central government cannot be suspended without the nod of Prime Minister Narendra Modi, a move aimed at allowing bureaucrats to take decisions without any fear of political backlash. A relief has also been provided in the revised rules to all-India services officers –IAS, IPS and IFoS –working in various states in the revised rules under which the Centre needs to be informed within 48 hours if any officer is suspended by them followed by a detailed report within a fortnight.last_img

A Different Dance

first_imgTapping of feet with the swaying rhythm of classical music is going to fill the chilly air of the city with the beginning of the 20th Annual Kathak Dance Festival – ‘Antarang’. Organised by the AAMAD Dance Centre, it is an annual dance festival that creates the opportunity for its students to present their training of Kathak on a professional platform. The festival will exhibit the talent of more than 100 artists including able and differently able people along with the presence of Dr Kamilini Asthana, chairperson, Advisory committee, kathak kendra as the chief guest. Also Read – Add new books to your shelf’Antarang’ will showcase traditional Kathak performances by the disciples of Rani Khanam of AAMAD dance centre. Apart from being a respected guru, Rani Khanam is also an empanelled artist in “outstanding category” of the Indian Council for Culture Relations, “Top graded” artist at the Delhi Doordarshan and the Director of Aamad. Along with it, some other performances aiming to grab the limelight includes a stylized dance form “Andaz-e-Raqs”, highlighting the contribution of Persian culture where the costumes play an intrinsic role in the kinetics of choreography, highly inspired by the Persian paintings and literature; “Shatapadi”, a “Shri Nand Nandan Nachat Sudhang” of Surdas and a performance called “Om Shanti” by the “specially able” artists to be performed on wheelchairs and amp; Crutches. These soul-stirring performances are aimed at recognizing the hidden potential of each person with disability. AAMAD, considered as one of the main integrated dance institute in India imparts training at a professional level. Imparting training to differently abled people to dance, they created a level in traditional and modern dance for more than two decades. With the most creative and unique initiative in the world of Indian performing arts, “Antarang” is sure to attract dance lovers with its powerful performances.last_img read more