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Biogeochemistry: Long-term effects of permafrost thaw

Nature - Wed, 09/28/2016 - 00:00

Biogeochemistry: Long-term effects of permafrost thaw

Nature 537, 7622 (2016). doi:10.1038/537625a

Authors: Donatella Zona

Carbon emissions from the Arctic tundra could increase drastically as global warming thaws permafrost. Clues now obtained about the long-term effects of such thawing on carbon dioxide emissions highlight the need for more data.

Categories: Literature

Physiology: Forecast for water balance

Nature - Wed, 09/28/2016 - 00:00

Physiology: Forecast for water balance

Nature 537, 7622 (2016). doi:10.1038/537626a

Authors: Michael J. Krashes

Disturbances in internal water equilibrium can be debilitating for mammals. Two studies pinpoint areas of the mouse brain that respond to and anticipate thirst, preserving systematic fluid regulation. See Letters p.680 & p.685

Categories: Literature

Chemistry: Small molecular replicators go organic

Nature - Wed, 09/28/2016 - 00:00

Chemistry: Small molecular replicators go organic

Nature 537, 7622 (2016). doi:10.1038/537627a

Authors: Annette F. Taylor

The emergence of complex, dynamic molecular behaviour might have had a role in the origin of life. Such behaviour has now been seen in a reaction network involving small, organic, self-replicating molecules of biological relevance. See Letter p.656

Categories: Literature

A method for imaging and spectroscopy using γ-rays and magnetic resonance

Nature - Wed, 09/28/2016 - 00:00

A method for imaging and spectroscopy using γ-rays and magnetic resonance

Nature 537, 7622 (2016). doi:10.1038/nature19775

Authors: Yuan Zheng, G. Wilson Miller, William A. Tobias & Gordon D. Cates

Magnetic resonance imaging (MRI) provides fine spatial resolution, spectral sensitivity and a rich variety of contrast mechanisms for diagnostic medical applications. Nuclear imaging using γ-ray cameras offers the benefits of using small quantities of radioactive tracers that seek specific targets of interest within the body. Here we describe an imaging and spectroscopic modality that combines favourable aspects of both approaches. Spatial information is encoded into the spin orientations of tiny amounts of a polarized radioactive tracer using pulses of both radio-frequency electromagnetic radiation and magnetic-field gradients, as in MRI. However, rather than detecting weak radio-frequency signals, imaging information is obtained through the detection of γ-rays. A single γ-ray detector can be used to acquire an image; no γ-ray camera is needed. We demonstrate the feasibility of our technique by producing images and spectra from a glass cell containing only about 4 × 1013 atoms (about 1 millicurie) of the metastable isomer 131mXe that were polarized using the laser technique of spin-exchange optical pumping. If the cell had instead been filled with water and imaged using conventional MRI, then it would have contained more than 1024 water molecules. The high sensitivity of our modality expands the breadth of applications of magnetic resonance, and could lead to a new class of radioactive tracers.

Categories: Literature

Autocatalytic, bistable, oscillatory networks of biologically relevant organic reactions

Nature - Wed, 09/28/2016 - 00:00

Autocatalytic, bistable, oscillatory networks of biologically relevant organic reactions

Nature 537, 7622 (2016). doi:10.1038/nature19776

Authors: Sergey N. Semenov, Lewis J. Kraft, Alar Ainla, Mengxia Zhao, Mostafa Baghbanzadeh, Victoria E. Campbell, Kyungtae Kang, Jerome M. Fox & George M. Whitesides

Networks of organic chemical reactions are important in life and probably played a central part in its origin. Network dynamics regulate cell division, circadian rhythms, nerve impulses and chemotaxis, and guide the development of organisms. Although out-of-equilibrium networks of chemical reactions have the potential to display emergent network dynamics such as spontaneous pattern formation, bistability and periodic oscillations, the principles that enable networks of organic reactions to develop complex behaviours are incompletely understood. Here we describe a network of biologically relevant organic reactions (amide formation, thiolate–thioester exchange, thiolate–disulfide interchange and conjugate addition) that displays bistability and oscillations in the concentrations of organic thiols and amides. Oscillations arise from the interaction between three subcomponents of the network: an autocatalytic cycle that generates thiols and amides from thioesters and dialkyl disulfides; a trigger that controls autocatalytic growth; and inhibitory processes that remove activating thiol species that are produced during the autocatalytic cycle. In contrast to previous studies that have demonstrated oscillations and bistability using highly evolved biomolecules (enzymes and DNA) or inorganic molecules of questionable biochemical relevance (for example, those used in Belousov–Zhabotinskii-type reactions), the organic molecules we use are relevant to metabolism and similar to those that might have existed on the early Earth. By using small organic molecules to build a network of organic reactions with autocatalytic, bistable and oscillatory behaviour, we identify principles that explain the ways in which dynamic networks relevant to life could have developed. Modifications of this network will clarify the influence of molecular structure on the dynamics of reaction networks, and may enable the design of biomimetic networks and of synthetic self-regulating and evolving chemical systems.

Categories: Literature

Clock-driven vasopressin neurotransmission mediates anticipatory thirst prior to sleep

Nature - Wed, 09/28/2016 - 00:00

Clock-driven vasopressin neurotransmission mediates anticipatory thirst prior to sleep

Nature 537, 7622 (2016). doi:10.1038/nature19756

Authors: C. Gizowski, C. Zaelzer & C. W. Bourque

Circadian rhythms have evolved to anticipate and adapt animals to the constraints of the earth’s 24-hour light cycle. Although the molecular processes that establish periodicity in clock neurons of the suprachiasmatic nucleus (SCN) are well understood, the mechanisms by which axonal projections from the central clock drive behavioural rhythms are unknown. Here we show that the sleep period in mice (Zeitgeber time, ZT0–12) is preceded by an increase in water intake promoted entirely by the central clock, and not motivated by physiological need. Mice denied this surge experienced significant dehydration near the end of the sleep period, indicating that this water intake contributes to the maintenance of overnight hydromineral balance. Furthermore, this effect relies specifically on the activity of SCN vasopressin (VP) neurons that project to thirst neurons in the OVLT (organum vasculosum lamina terminalis), where VP is released as a neurotransmitter. SCN VP neurons become electrically active during the anticipatory period (ZT21.5–23.5), and depolarize and excite OVLT neurons through the activation of postsynaptic VP V1a receptors and downstream non-selective cation channels. Optogenetic induction of VP release before the anticipatory period (basal period; ZT19.5–21.5) excited OVLT neurons and prompted a surge in water intake. Conversely, optogenetic inhibition of VP release during the anticipatory period inhibited the firing of OVLT neurons and prevented the corresponding increase in water intake. Our findings reveal the existence of anticipatory thirst, and demonstrate this behaviour to be driven by excitatory peptidergic neurotransmission mediated by VP release from central clock neurons.

Categories: Literature

Could California’s Gridlock Generate Electricity for the Grid?

Yale Environment 360 - Tue, 09/27/2016 - 11:56

California is testing whether its heavy traffic can produce not just emissions and air pollution, but electricity.

Traffic on Interstate 80 near Berkeley, Calif. The state’s Energy Commission says it will spend $2 million to examine the potential of using piezoelectric crystals embedded under asphalt as a way to send the energy created by moving cars to the grid. The crystals generate energy when compressed by the weight of moving cars, but tests of the technology at larger scales have failed or been canceled in Tokyo, Italy, and Israel, according to the Associated Press. California, therefore, “needs to figure out whether it can produce high returns without costing too much,” the AP writes. If successful, the technology could help the state reach its goal to generate 50 percent of its electricity from renewable sources by 2030. California is expected to hit a 25 percent renewables target by the end of this year.

Categories: Environmental News

Young researchers thrive in life after academia

Nature - Tue, 09/27/2016 - 00:00

Young researchers thrive in life after academia

Nature 537, 7622 (2016). doi:10.1038/537585a

Alternative career paths should be celebrated, not seen as a compromise.

Categories: Literature

Zimbabwean scientists fight to preserve national academy

Nature - Tue, 09/27/2016 - 00:00

Zimbabwean scientists fight to preserve national academy

Nature 537, 7622 (2016). http://www.nature.com/doifinder/10.1038/nature.2016.20670

Author: Sarah Wild

Research struggles in a country in economic free-fall.

Categories: Literature

Elephants in Africa Suffer Large Declines as Poaching Worsens in the Region

Yale Environment 360 - Mon, 09/26/2016 - 11:19

Elephant populations in Africa fell about 20 percent between 2006 and 2015 — the worst decline in a quarter-century, according to a

An African elephant. new report by the International Union for Conservation of Nature (IUCN). The continent’s elephant population dropped by 111,000 individuals over the last decade. The IUCN said a recent surge in poaching for ivory, which it called “the worst that Africa has experienced since the 1970s and 1980s,” is largely to blame for the decline. East Africa, for example, has lost almost 50 percent of its historical elephant population, according to the report. In West Africa, 12 populations of elephants have been completely lost since 2006. “It is shocking, but not surprising that poaching has taken such a dramatic toll on this iconic species,” IUCN director general Inger Andersen said in a statement. The IUCN also named habitat loss as a major contributor to the decline.

Categories: Environmental News

As Arctic Ocean Ice Disappears, Global Climate Impacts Intensify

Yale Environment 360 - Mon, 09/26/2016 - 07:36

The top of the world is turning from white to blue in summer as the ice that has long covered the north polar seas melts away. This monumental change is triggering a cascade of effects that will amplify global warming and could destabilize the global climate system. BY PETER WADHAMS

Categories: Environmental News

Daring Chinese telescope is poised to transform astronomy

Nature - Mon, 09/26/2016 - 00:00

Daring Chinese telescope is poised to transform astronomy

Nature 537, 7622 (2016). http://www.nature.com/doifinder/10.1038/537593a

Author: David Cyranoski

Construction of the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) is complete, but debugging has only just begun.

Categories: Literature

World’s Coffee Supply Threatened by Climate Change, Report Says

Yale Environment 360 - Fri, 09/23/2016 - 01:35

A new report says that climate change could significantly reduce the amount of suitable land on which to grow coffee and lead to an increase in outbreaks of diseases that threaten the crop. The report — released by the Australian non-profit, the Climate Institute — warns that under current emissions scenarios, coffee-growing regions could see a 50 percent drop in the acreage fit to raise coffee plants, which need a precise combination of temperature and precipitation to thrive. Rising temperatures are also likely to lead to an increase in diseases like coffee rust and pests like the coffee berry borer, the report said. Major coffee-producing countries in the “bean belt” — including Colombia, Mexico, Brazil, Ethiopia, and Vietnam — have already become less hospitable because of shifts in weather patterns, the report said. “It’s a severe threat,” said an executive at U.S.-based Peet’s Coffee.

Categories: Environmental News

What’s Killing the Native Birds in The Mountain Forests of Kauai?

Yale Environment 360 - Thu, 09/22/2016 - 00:42

The few remaining species of native forest birds left on the Hawaiian island of Kauai have suffered population declines so severe — 98 percent in one case — that some are near extinction.

Eben Paxton The cause of the collapse, according to a recent study in the journal Science Advances, is not alien plants or predators, but rather warming temperatures that have enabled non-native mosquitoes carrying deadly avian malaria to invade the birds’ high-elevation strongholds. In an interview with Yale Environment 360, Eben Paxton, an avian ecologist with the U.S. Geological Survey and the study’s lead author, says his group’s research showed that the mosquitoes moved into the Alakai Plateau over the last decade, infecting the birds and pushing their populations to a tipping point. He cites a number of approaches for eradicating the mosquitoes, including releasing irradiated infertile males and using genetically modified mosquitoes. “The way that we view Kauai,” he says, “is that it's an early warning system for the rest of the islands.”
Read the interview.

Categories: Environmental News

Paris Climate Agreement Moves One Step Closer to Entering Into Force

Yale Environment 360 - Wed, 09/21/2016 - 10:16

Thirty-one countries officially joined the Paris climate accords this week at United Nations’ meetings in New York City.

UN secretary general Ban Ki-moon. The announcements bring the total number of countries joining the Paris Agreement to 60, representing 48 percent of global emissions. Once nations that generate 55 percent of global emissions officially join, the agreement will enter into force within 30 days. The new countries include Brazil, the world’s seventh-largest emitter of carbon dioxide; Argentina; Mexico; and the United Arab Emirates. China and the United States officially joined the agreement earlier this month. UN Secretary General Ban Ki-moon predicted the agreement, created in December last year, would enter into force by the end of this year. “What once seemed impossible now seems inevitable,” Ban said.

Categories: Environmental News

Facebook couple commits $3 billion to cure disease

Nature - Wed, 09/21/2016 - 00:00

Facebook couple commits $3 billion to cure disease

Nature 537, 7622 (2016). http://www.nature.com/doifinder/10.1038/nature.2016.20649

Author: Erika Check Hayden

Chan Zuckerberg Initiative aims to have major impact by 2100.

Categories: Literature

Worldwide brain-mapping project sparks excitement — and concern

Nature - Wed, 09/21/2016 - 00:00

Worldwide brain-mapping project sparks excitement — and concern

Nature 537, 7622 (2016). http://www.nature.com/doifinder/10.1038/nature.2016.20658

Author: Sara Reardon

Worries include how to coordinate research programmes and resources from different countries.

Categories: Literature

The architecture of the mammalian respirasome

Nature - Wed, 09/21/2016 - 00:00

The architecture of the mammalian respirasome

Nature 537, 7622 (2016). doi:10.1038/nature19359

Authors: Jinke Gu, Meng Wu, Runyu Guo, Kaige Yan, Jianlin Lei, Ning Gao & Maojun Yang

The respiratory chain complexes I, III and IV (CI, CIII and CIV) are present in the bacterial membrane or the inner mitochondrial membrane and have a role of transferring electrons and establishing the proton gradient for ATP synthesis by complex V. The respiratory chain complexes

Categories: Literature

The architecture of respiratory supercomplexes

Nature - Wed, 09/21/2016 - 00:00

The architecture of respiratory supercomplexes

Nature 537, 7622 (2016). doi:10.1038/nature19774

Authors: James A. Letts, Karol Fiedorczuk & Leonid A. Sazanov

Mitochondrial electron transport chain complexes are organized into supercomplexes responsible for carrying out cellular respiration. Here we present three architectures of mammalian (ovine) supercomplexes determined by cryo-electron microscopy. We identify two distinct arrangements of supercomplex CICIII2CIV (the respirasome)—a major ‘tight’ form and a

Categories: Literature

Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses

Nature - Wed, 09/21/2016 - 00:00

Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses

Nature 537, 7622 (2016). doi:10.1038/nature19366

Authors: Simon Roux, Jennifer R. Brum, Bas E. Dutilh, Shinichi Sunagawa, Melissa B. Duhaime, Alexander Loy, Bonnie T. Poulos, Natalie Solonenko, Elena Lara, Julie Poulain, Stéphane Pesant, Stefanie Kandels-Lewis, Céline Dimier, Marc Picheral, Sarah Searson, Corinne Cruaud, Adriana Alberti, Carlos M. Duarte, Josep M. Gasol, Dolors Vaqué, Peer Bork, Silvia G. Acinas, Patrick Wincker & Matthew B. Sullivan

Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the sampling and cultivation of viruses, genome-level viral diversity remains poorly described and grossly understudied, with less than 1% of observed surface-ocean viruses known. Here we assemble complete genomes and large genomic fragments from both surface- and deep-ocean viruses sampled during the Tara Oceans and Malaspina research expeditions, and analyse the resulting ‘global ocean virome’ dataset to present a global map of abundant, double-stranded DNA viruses complete with genomic and ecological contexts. A total of 15,222 epipelagic and mesopelagic viral populations were identified, comprising 867 viral clusters (defined as approximately genus-level groups). This roughly triples the number of known ocean viral populations and doubles the number of candidate bacterial and archaeal virus genera, providing a near-complete sampling of epipelagic communities at both the population and viral-cluster level. We found that 38 of the 867 viral clusters were locally or globally abundant, together accounting for nearly half of the viral populations in any global ocean virome sample. While two-thirds of these clusters represent newly described viruses lacking any cultivated representative, most could be computationally linked to dominant, ecologically relevant microbial hosts. Moreover, we identified 243 viral-encoded auxiliary metabolic genes, of which only 95 were previously known. Deeper analyses of four of these auxiliary metabolic genes (dsrC, soxYZ, P-II (also known as glnB) and amoC) revealed that abundant viruses may directly manipulate sulfur and nitrogen cycling throughout the epipelagic ocean. This viral catalog and functional analyses provide a necessary foundation for the meaningful integration of viruses into ecosystem models where they act as key players in nutrient cycling and trophic networks.

Categories: Literature

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