Brazilian courts tussle over unproven cancer treatment

Nature 527, 7579 (2015). http://www.nature.com/doifinder/10.1038/527420a

Author: Heidi Ledford

Patients demand access to compound despite lack of clinical testing.

The fragile framework

Nature 527, 7579 (2015). http://www.nature.com/doifinder/10.1038/527427a

Authors: Richard Monastersky & Nick Sousanis

A Nature comic examines the 25-year quest for a climate treaty. Can nations unite to save Earth’s climate?

Is the 2 °C world a fantasy?

Nature 527, 7579 (2015). http://www.nature.com/doifinder/10.1038/527436a

Author: Jeff Tollefson

Countries have pledged to limit global warming to 2 °C, and climate models say that is still possible. But only with heroic — and unlikely — efforts.

Salmon approval heralds rethink of transgenic animals

Nature 527, 7579 (2015). http://www.nature.com/doifinder/10.1038/527417a

Author: Heidi Ledford

Long-awaited decision by US government authorizes the first genetically engineered animal to be sold as food.

Climate optimism builds ahead of Paris talks

Nature 527, 7579 (2015). http://www.nature.com/doifinder/10.1038/527418a

Author: Jeff Tollefson

Emission pledges raise hopes for an international treaty.

Text-mining block prompts online response

Nature 527, 7579 (2015). doi:10.1038/527413f

Author: Mollie Bloudoff-Indelicato

A statistician says a major scientific publisher is hindering his research.

Green Climate Fund faces slew of criticism

Nature 527, 7579 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.18815

Author: Sanjay Kumar

First tranche of aid projects prompts concern over operations of fund for developing nations.

Leap-second decision delayed by eight years

Nature 527, 7579 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.18855

Author: Elizabeth Gibney

Some want to scrap adjustment that keeps atomic time in sync with Earth's rotation.

Genomics: Acorn worms in a nutshell

Nature 527, 7579 (2015). doi:10.1038/nature16315

Authors: Casey W. Dunn

The genome sequences of two members of the hemichordate group of marine invertebrates bring the evolution of their relatives, including vertebrates, into sharper focus. See Article p.459

Circadian clocks: A receptor for subtle temperature changes

Nature 527, 7579 (2015). doi:10.1038/nature16316

Authors: François Rouyer & Abhishek Chatterjee

The protein IR25a is best known for its role as an odour receptor in flies, but an analysis reveals that it also acts to synchronize the circadian clock by sensing small temperature fluctuations. See Letter p.516

Hemichordate genomes and deuterostome origins

Nature 527, 7579 (2015). doi:10.1038/nature16150

Authors: Oleg Simakov, Takeshi Kawashima, Ferdinand Marlétaz, Jerry Jenkins, Ryo Koyanagi, Therese Mitros, Kanako Hisata, Jessen Bredeson, Eiichi Shoguchi, Fuki Gyoja, Jia-Xing Yue, Yi-Chih Chen, Robert M. Freeman, Akane Sasaki, Tomoe Hikosaka-Katayama, Atsuko Sato, Manabu Fujie, Kenneth W. Baughman, Judith Levine, Paul Gonzalez, Christopher Cameron, Jens H. Fritzenwanker, Ariel M. Pani, Hiroki Goto, Miyuki Kanda, Nana Arakaki, Shinichi Yamasaki, Jiaxin Qu, Andrew Cree, Yan Ding, Huyen H. Dinh, Shannon Dugan, Michael Holder, Shalini N. Jhangiani, Christie L. Kovar, Sandra L. Lee, Lora R. Lewis, Donna Morton, Lynne V. Nazareth, Geoffrey Okwuonu, Jireh Santibanez, Rui Chen, Stephen Richards, Donna M. Muzny, Andrew Gillis, Leonid Peshkin, Michael Wu, Tom Humphreys, Yi-Hsien Su, Nicholas H. Putnam, Jeremy Schmutz, Asao Fujiyama, Jr-Kai Yu, Kunifumi Tagawa, Kim C. Worley, Richard A. Gibbs, Marc W. Kirschner, Christopher J. Lowe, Noriyuki Satoh, Daniel S. Rokhsar & John Gerhart

Acorn worms, also known as enteropneust (literally, ‘gut-breathing’) hemichordates, are marine invertebrates that share features with echinoderms and chordates. Together, these three phyla comprise the deuterostomes. Here we report the draft genome sequences of two acorn worms, Saccoglossus kowalevskii and Ptychodera flava. By

Sweet and bitter taste in the brain of awake behaving animals

Nature 527, 7579 (2015). doi:10.1038/nature15763

Authors: Yueqing Peng, Sarah Gillis-Smith, Hao Jin, Dimitri Tränkner, Nicholas J. P. Ryba & Charles S. Zuker

Taste is responsible for evaluating the nutritious content of food, guiding essential appetitive behaviours, preventing the ingestion of toxic substances, and helping to ensure the maintenance of a healthy diet. Sweet and bitter are two of the most salient sensory percepts for humans and other animals; sweet taste allows the identification of energy-rich nutrients whereas bitter warns against the intake of potentially noxious chemicals. In mammals, information from taste receptor cells in the tongue is transmitted through multiple neural stations to the primary gustatory cortex in the brain. Recent imaging studies have shown that sweet and bitter are represented in the primary gustatory cortex by neurons organized in a spatial map, with each taste quality encoded by distinct cortical fields. Here we demonstrate that by manipulating the brain fields representing sweet and bitter taste we directly control an animal’s internal representation, sensory perception, and behavioural actions. These results substantiate the segregation of taste qualities in the cortex, expose the innate nature of appetitive and aversive taste responses, and illustrate the ability of gustatory cortex to recapitulate complex behaviours in the absence of sensory input.

Drosophila Ionotropic Receptor 25a mediates circadian clock resetting by temperature

Nature 527, 7579 (2015). doi:10.1038/nature16148

Authors: Chenghao Chen, Edgar Buhl, Min Xu, Vincent Croset, Johanna S. Rees, Kathryn S. Lilley, Richard Benton, James J. L. Hodge & Ralf Stanewsky

Circadian clocks are endogenous timers adjusting behaviour and physiology with the solar day. Synchronized circadian clocks improve fitness and are crucial for our physical and mental well-being. Visual and non-visual photoreceptors are responsible for synchronizing circadian clocks to light, but clock-resetting is also achieved by alternating day and night temperatures with only 2–4 °C difference. This temperature sensitivity is remarkable considering that the circadian clock period (~24 h) is largely independent of surrounding ambient temperatures. Here we show that Drosophila Ionotropic Receptor 25a (IR25a) is required for behavioural synchronization to low-amplitude temperature cycles. This channel is expressed in sensory neurons of internal stretch receptors previously implicated in temperature synchronization of the circadian clock. IR25a is required for temperature-synchronized clock protein oscillations in subsets of central clock neurons. Extracellular leg nerve recordings reveal temperature- and IR25a-dependent sensory responses, and IR25a misexpression confers temperature-dependent firing of heterologous neurons. We propose that IR25a is part of an input pathway to the circadian clock that detects small temperature differences. This pathway operates in the absence of known ‘hot’ and ‘cold’ sensors in the Drosophila antenna, revealing the existence of novel periphery-to-brain temperature signalling channels.

A perisinusoidal niche for extramedullary haematopoiesis in the spleen

Nature 527, 7579 (2015). doi:10.1038/nature15530

Authors: Christopher N. Inra, Bo O. Zhou, Melih Acar, Malea M. Murphy, James Richardson, Zhiyu Zhao & Sean J. Morrison

Haematopoietic stresses mobilize haematopoietic stem cells (HSCs) from the bone marrow to the spleen and induce extramedullary haematopoiesis (EMH). However, the cellular nature of the EMH niche is unknown. Here we assessed the sources of the key niche factors, SCF (also known as KITL) and

Ubiquitous time variability of integrated stellar populations

Nature 527, 7579 (2015). doi:10.1038/nature15731

Authors: Charlie Conroy, Pieter G. van Dokkum & Jieun Choi

Long-period variable stars arise in the final stages of the asymptotic giant branch phase of stellar evolution. They have periods of up to about 1,000 days and amplitudes that can exceed a factor of three in the I-band flux. These stars pulsate predominantly in their fundamental mode, which is a function of mass and radius, and so the pulsation periods are sensitive to the age of the underlying stellar population. The overall number of long-period variables in a population is directly related to their lifetimes, which is difficult to predict from first principles because of uncertainties associated with stellar mass-loss and convective mixing. The time variability of these stars has not previously been taken into account when modelling the spectral energy distributions of galaxies. Here we construct time-dependent stellar population models that include the effects of long-period variable stars, and report the ubiquitous detection of this expected ‘pixel shimmer’ in the massive metal-rich galaxy M87. The pixel light curves display a variety of behaviours. The observed variation of 0.1 to 1 per cent is very well matched to the predictions of our models. The data provide a strong constraint on the properties of variable stars in an old and metal-rich stellar population, and we infer that the lifetime of long-period variables in M87 is shorter by approximately 30 per cent compared to predictions from the latest stellar evolution models.

Cell fate: Transition loses its invasive edge

Nature 527, 7579 (2015). doi:10.1038/nature16313

Authors: Shyamala Maheswaran & Daniel A. Haber

Two studies provide evidence that epithelial tumour cells do not need to transition to a mesenchymal-cell state to form metastases, but that this process does contribute to drug resistance. See Article p.472 & Letter p.525

Epithelial-to-mesenchymal transition is not required for lung metastasis but contributes to chemoresistance

Nature 527, 7579 (2015). doi:10.1038/nature15748

Authors: Kari R. Fischer, Anna Durrans, Sharrell Lee, Jianting Sheng, Fuhai Li, Stephen T. C. Wong, Hyejin Choi, Tina El Rayes, Seongho Ryu, Juliane Troeger, Robert F. Schwabe, Linda T. Vahdat, Nasser K. Altorki, Vivek Mittal & Dingcheng Gao

The role of epithelial-to-mesenchymal transition (EMT) in metastasis is a longstanding source of debate, largely owing to an inability to monitor transient and reversible EMT phenotypes in vivo. Here we establish an EMT lineage-tracing system to monitor this process in mice, using a mesenchymal-specific

Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way

Nature 527, 7579 (2015). doi:10.1038/nature15747

Authors: L. M. Howes, A. R. Casey, M. Asplund, S. C. Keller, D. Yong, D. M. Nataf, R. Poleski, K. Lind, C. Kobayashi, C. I. Owen, M. Ness, M. S. Bessell, G. S. Da Costa, B. P. Schmidt, P. Tisserand, A. Udalski, M. K. Szymański, I. Soszyński, G. Pietrzyński, K. Ulaczyk, Ł. Wyrzykowski, P. Pietrukowicz, J. Skowron, S. Kozłowski & P. Mróz

The first stars are predicted to have formed within 200 million years after the Big Bang, initiating the cosmic dawn. A true first star has not yet been discovered, although stars with tiny amounts of elements heavier than helium (‘metals’) have been found in the outer regions (‘halo’) of the Milky Way. The first stars and their immediate successors should, however, preferentially be found today in the central regions (‘bulges’) of galaxies, because they formed in the largest over-densities that grew gravitationally with time. The Milky Way bulge underwent a rapid chemical enrichment during the first 1–2 billion years, leading to a dearth of early, metal-poor stars. Here we report observations of extremely metal-poor stars in the Milky Way bulge, including one star with an iron abundance about 10,000 times lower than the solar value without noticeable carbon enhancement. We confirm that most of the metal-poor bulge stars are on tight orbits around the Galactic Centre, rather than being halo stars passing through the bulge, as expected for stars formed at redshifts greater than 15. Their chemical compositions are in general similar to typical halo stars of the same metallicity although intriguing differences exist, including lower abundances of carbon.

Single-molecule sequencing of the desiccation-tolerant grass Oropetium thomaeum

Nature 527, 7579 (2015). doi:10.1038/nature15714

Authors: Robert VanBuren, Doug Bryant, Patrick P. Edger, Haibao Tang, Diane Burgess, Dinakar Challabathula, Kristi Spittle, Richard Hall, Jenny Gu, Eric Lyons, Michael Freeling, Dorothea Bartels, Boudewijn Ten Hallers, Alex Hastie, Todd P. Michael & Todd C. Mockler

Plant genomes, and eukaryotic genomes in general, are typically repetitive, polyploid and heterozygous, which complicates genome assembly. The short read lengths of early Sanger and current next-generation sequencing platforms hinder assembly through complex repeat regions, and many draft and reference genomes are fragmented, lacking skewed GC and repetitive intergenic sequences, which are gaining importance due to projects like the Encyclopedia of DNA Elements (ENCODE). Here we report the whole-genome sequencing and assembly of the desiccation-tolerant grass Oropetium thomaeum. Using only single-molecule real-time sequencing, which generates long (>16 kilobases) reads with random errors, we assembled 99% (244 megabases) of the Oropetium genome into 625 contigs with an N50 length of 2.4 megabases. Oropetium is an example of a ‘near-complete’ draft genome which includes gapless coverage over gene space as well as intergenic sequences such as centromeres, telomeres, transposable elements and rRNA clusters that are typically unassembled in draft genomes. Oropetium has 28,466 protein-coding genes and 43% repeat sequences, yet with 30% more compact euchromatic regions it is the smallest known grass genome. The Oropetium genome demonstrates the utility of single-molecule real-time sequencing for assembling high-quality plant and other eukaryotic genomes, and serves as a valuable resource for the plant comparative genomics community.

Epithelial-to-mesenchymal transition is dispensable for metastasis but induces chemoresistance in pancreatic cancer

Nature 527, 7579 (2015). doi:10.1038/nature16064

Authors: Xiaofeng Zheng, Julienne L. Carstens, Jiha Kim, Matthew Scheible, Judith Kaye, Hikaru Sugimoto, Chia-Chin Wu, Valerie S. LeBleu & Raghu Kalluri

Diagnosis of pancreatic ductal adenocarcinoma (PDAC) is associated with a dismal prognosis despite current best therapies; therefore new treatment strategies are urgently required. Numerous studies have suggested that epithelial-to-mesenchymal transition (EMT) contributes to early-stage dissemination of cancer cells and is pivotal for invasion and metastasis of PDAC. EMT is associated with phenotypic conversion of epithelial cells into mesenchymal-like cells in cell culture conditions, although such defined mesenchymal conversion (with spindle-shaped morphology) of epithelial cells in vivo is rare, with quasi-mesenchymal phenotypes occasionally observed in the tumour (partial EMT). Most studies exploring the functional role of EMT in tumours have depended on cell-culture-induced loss-of-function and gain-of-function experiments involving EMT-inducing transcription factors such as Twist, Snail and Zeb1 (refs 2, 3, 7, 8, 9, 10). Therefore, the functional contribution of EMT to invasion and metastasis remains unclear, and genetically engineered mouse models to address a causal connection are lacking. Here we functionally probe the role of EMT in PDAC by generating mouse models of PDAC with deletion of Snail or Twist, two key transcription factors responsible for EMT. EMT suppression in the primary tumour does not alter the emergence of invasive PDAC, systemic dissemination or metastasis. Suppression of EMT leads to an increase in cancer cell proliferation with enhanced expression of nucleoside transporters in tumours, contributing to enhanced sensitivity to gemcitabine treatment and increased overall survival of mice. Collectively, our study suggests that Snail- or Twist-induced EMT is not rate-limiting for invasion and metastasis, but highlights the importance of combining EMT inhibition with chemotherapy for the treatment of pancreatic cancer.