Aug 08, 2016

Magazine

Feature

Angry voters may turn back the clocks
• Michael Gross
Science, the environment, and efforts to mitigate climate change are among the likely casualties when the UK goes through with the exit from the European Union. Within a year of this vote, electoral success for populists in the US and in France could bring a U-turn for Western civilisation and make it renounce our current ideas of progress.

Book review

A wild life indeed
• Jonathan B. Losos
In a five-year span in the early 1970s, Robert Trivers published a series of five extraordinarily influential papers [1–5] that provided the theoretical underpinning for much of modern evolutionary biology. These papers cover reciprocal altruism, parent–offspring conflict, parental investment and sexual selection (a book chapter cited more than 10,000 times!), the determinants of sex ratio, and haplodiploidy and the evolution of social organization.

Q & A

John M. Archibald
• John M. Archibald
Interview with John Archibald, who studies eukaryotic evolution at Dalhousie University.

Quick guide

Salamandra
• Wouter Beukema,
• Jeroen Speybroeck,
• Guillermo Velo-Antón
Beukema et al. Introduce the genus salamandra comprising the well-known fire salamanders.

Correspondences

The origin of ambling horses
• Saskia Wutke,
• Leif Andersson,
• Norbert Benecke,
• Edson Sandoval-Castellanos,
• Javier Gonzalez,
• Jón Hallsteinn Hallsson,
• Lembi Lõugas,
• Ola Magnell,
• Arturo Morales-Muniz,
• Ludovic Orlando,
• Albína Hulda Pálsdóttir,
• Monika Reissmann,
• Mariana B. Muñoz-Rodríguez,
• Matej Ruttkay,
• Alexandra Trinks,
• Michael Hofreiter,
• Arne Ludwig
Wutke et al. genotyped a genetic marker associated with ambling in horses in a large number of ancient samples and find that the ambling allele originally arose in medieval England from where it came to Iceland.
What is the association between religious affiliation and children’s altruism?
• Azim F. Shariff,
• Aiyana K. Willard,
• Michael Muthukrishna,
• Stephanie R. Kramer,
• Joseph Henrich
Shariff et al. find that reanalysis of data reported to show a negative relationship between religiosity and generosity lead them to different conclusions.

Dispatches

Neuroscience: Hunger Pangs in the Fly Brain
• Andreas Schoofs,
• Michael J. Pankratz
Which neurons in the brain become engaged when the body is deprived of food? A new study addresses this question using the vinegar fly Drosophila melanogaster, examining a group of neurons in the brain that show alterations in neural activity when flies are satiated or starved.

Autophagy: Press and Push for Destruction
• Jörg Höhfeld
Recent publications illustrate an extensive crosstalk between the actin cytoskeleton and autophagy, a program for self-digestion. Actin polymerization provides a pushing force for organelle shaping and trafficking during autophagy, but the cytoskeleton is also targeted by autophagy under mechanical strain.

Retinal Physiology: Non-Bipolar-Cell Excitatory Drive in the Inner Retina
• Tom Baden,
• Thomas Euler
The long-held view that bipolar cells provide the exclusive excitatory drive to the mammalian inner retina has been challenged: new studies indicate that, instead, at least two cells that lack the dendrites characteristic for bipolar cells, and therefore resemble amacrine cells, excite inner retinal circuits using glutamate.

Ecology: The Upside-Down World of Coral Reef Predators
• Colin A. Simpfendorfer,
• Michelle R. Heupel
Examination of a large aggregation of sharks demonstrates that trophic pyramids with greater amounts of high-level predators than prey can occur on coral reefs. This is possible because the high level predators obtain food from sources outside their home location.

Chromatin: Polycomb Group SAMs Unite
• Chongwoo A. Kim,
• Nicole J. Francis
Polycomb Group (PcG) proteins assemble a chromatin state that maintains developmental gene repression. A new study combining structure and in vivo analysis details a molecular network from DNA recognition to PcG recruitment, highlighting the essential role of Sterile Alpha Motifs.

Neuroscience: Peeking Under the Sombrero
• Michael B. Manookin
A recent study has introduced a new analytical approach to understanding neural circuits which has revealed previously hidden neural interactions in a large population of cells in the primate retina. The neural circuit described likely contributes to encoding visual motion.
Wound Signaling: Monkeywrenching Macrophage Migration with Microscopes, Movies, and Math
• Michael J. Galko
Drosophila hemocytes (blood cells) have emerged as a powerful system to image wound-induced inflammatory responses in vivo. New work reveals that layering mathematical modeling on top of imaging may be the most powerful tool yet for determining the properties of wound-induced signals.

Behavior: Knowing When to Walk Away, Knowing When to Run
• Herman Pontzer
A new model has been proposed indicating that humans and other animals weigh the metabolic cost of pursuit in deciding how fast to move toward a given reward, providing a powerful framework for understanding behavior.

Review

Actomyosin Ring Formation and Tension Generation in Eukaryotic Cytokinesis
• Thomas H. Cheffings,
• Nigel J. Burroughs,
• Mohan K. Balasubramanian
In this Review, Cheffings et al. discuss how eukaryotic cells position and form their actomyosin ring during cytokinesis and then examine potential mechanisms for generating the contractile stress that drives ring constriction and cell division.

Articles

Identification of a Retinal Circuit for Recurrent Suppression Using Indirect Electrical Imaging
• Martin Greschner,
• Alexander K. Heitman,
• Greg D. Field,
• Peter H. Li,
• Daniel Ahn,
• Alexander Sher,
• Alan M. Litke,
• E.J. Chichilnisky
Greschner et al. discovered an amacrine subcircuit that recurrently modulates the activity of retinal ganglion cells in the magnocellular visual pathway of primates. The amacrine cells are electrically coupled to ON parasol cells, and their signals propagate over long distances, producing reciprocal inhibition of distant ON parasol cells.

Automatic Segmentation of Drosophila Neural Compartments Using GAL4 Expression Data Reveals Novel Visual Pathways
• Karin Panser,
• Laszlo Tirian,
• Florian Schulze,
• Santiago Villalba,
• Gregory S.X.E. Jefferis,
• Katja Bühler,
• Andrew D. Straw
In this study, Panser et al. took advantage of recent, genome-wide Drosophila enhancer expression datasets consisting of 3D brain image volumes and used clustering to automatically predict brain structures. They validated previously described regions and used novel predictions to make an atlas of the fly optic glomeruli.

Phagocytosis Enhances Lysosomal and Bactericidal Properties by Activating the Transcription Factor TFEB
• Matthew A. Gray,
• Christopher H. Choy,
• Roya M. Dayam,
• Erika Ospina-Escobar,
• Alexander Somerville,
• Xuan Xiao,
• Shawn M. Ferguson,
• Roberto J. Botelho
Gray et al. show that phagocytosis enhances lysosomal and bactericidal activity in macrophages by activating the transcription factor TFEB and boosting lysosome gene expression. TFEB activation requires lysosomal Ca²⁺ release. Overall, this work suggests that macrophages can boost lysosome activity to handle successive rounds of phagocytosis.

Drosophila SLC5A11 Mediates Hunger by Regulating K⁺ Channel Activity
• Jin-Yong Park,
• Monica Dus,
• Seonil Kim,
• Farhan Abu,
• Makoto I. Kanai,
• Bernardo Rudy,
• Greg S.B. Suh
Park et al. reveal an underlying mechanism by which SLC5A11 regulates feeding in Drosophila. The starvation-induced increase in SLC5A11 expression enhances the excitability of EB R4 neurons by inhibiting the activity of KCNQ channels, thereby promoting feeding and hunger-driven behaviors.

Systems Analysis of the Dynamic Inflammatory Response to Tissue Damage Reveals Spatiotemporal Properties of the Wound Attractant Gradient
• Helen Weavers,
• Juliane Liepe,
• Aaron Sim,
• Will Wood,
• Paul Martin,
• Michael P.H. Stumpf
Weavers et al. use Bayesian modeling of the inflammatory response to tissue damage in Drosophila to extract novel spatiotemporal properties of the wound attractant, including its diffusion coefficient, duration, and source of signal production. Modeling the response to two competing attractants uncovers a period of immune cell desensitization.

Reports

Cytokinin and Auxin Display Distinct but Interconnected Distribution and Signaling Profiles to Stimulate Cambial Activity
• Juha Immanen,
• Kaisa Nieminen,
• Olli-Pekka Smolander,
• Mikiko Kojima,
• Juan Alonso Serra,
• Patrik Koskinen,
• Jing Zhang,
• Annakaisa Elo,
• Ari Pekka Mähönen,
• Nathaniel Street,
• Rishikesh P. Bhalerao,
• Lars Paulin,
• Petri Auvinen,
• Hitoshi Sakakibara,
• Ykä Helariutta
A new report explores how two major phytohormones, cytokinin and auxin, contribute to the control of tree trunk growth. Immanen et al. show that by boosting cytokinin biosynthesis, they can both increase auxin level and stimulate lignocellulosic biomass production. Both hormones represent optimal targets for tree breeding and forest biotechnology.

Changing Balance of Spinal Cord Excitability and Nociceptive Brain Activity in Early Human Development
• Caroline Hartley,
• Fiona Moultrie,
• Deniz Gursul,
• Amy Hoskin,
• Eleri Adams,
• Richard Rogers,
• Rebeccah Slater
Hartley et al. demonstrate that the maturation of nociceptive brain activity is concomitant with the refinement of reflex withdrawal in human infants. This change in balance of spinal cord excitability and nociceptive brain activity may arise due to the emergence of top-down inhibitory pathways during early human development.

Dpp/BMP2-4 Mediates Signaling from the D-Quadrant Organizer in a Spiralian Embryo
• J. David Lambert,
• Adam B. Johnson,
• Chelsea N. Hudson,
• Amanda Chan
Lambert et al. show that in a mollusk embryo, the Dpp/BMP2-4 pathway mediates the activity of the D-quadrant organizer, which is found in a number of groups with spiralian development. Unlike some other systems, here the pathway activates, rather than inhibits, neuroectoderm specification.

Extreme Inverted Trophic Pyramid of Reef Sharks Supported by Spawning Groupers
• Johann Mourier,
• Jeffrey Maynard,
• Valeriano Parravicini,
• Laurent Ballesta,
• Eric Clua,
• Michael L. Domeier,
• Serge Planes
Mourier et al. report extremely high shark biomass in pristine Fakarava pass, French Polynesia, producing an inverted trophic pyramid. To escape such constraints, predators typically forage long range on multiple pyramids. This study presents a new mechanism in which subsidies directly come to predators in the form of spawning aggregations.

Networks of Food Sharing Reveal the Functional Significance of Multilevel Sociality in Two Hunter-Gatherer Groups
• Mark Dyble,
• James Thompson,
• Daniel Smith,
• Gul Deniz Salali,
• Nikhil Chaudhary,
• Abigail E. Page,
• Lucio Vinicuis,
• Ruth Mace,
• Andrea Bamberg Migliano
Dyble et al. explore networks of food sharing among Agta and Mbendjele hunter-gatherers and identify three levels of social organization: the household, cluster, and camp. Their results suggest that this multilevel social system may provide individuals with access to the range of cooperative relationships that are vital in a foraging economy.

On the Encoding of Panoramic Visual Scenes in Navigating Wood Ants
• Cornelia Buehlmann,
• Joseph L. Woodgate,
• Thomas S. Collett
Buehlmann et al. infer how navigating ants encode a two-shape panorama. Imagine a ring of beads fixed on top of an ant’s head, of which two are colored. Each colored bead denotes the horizontal position of the center of mass of one shape learned when approaching the goal. The ant then aims at the goal by turning to align both beads with the shapes.

Auditory Efferent System Modulates Mosquito Hearing
• Marta Andrés,
• Marvin Seifert,
• Christian Spalthoff,
• Ben Warren,
• Lukas Weiss,
• Diego Giraldo,
• Margret Winkler,
• Stephanie Pauls,
• Martin C. Göpfert
Andrés et al. report that auditory efferent systems, as known from vertebrate hearing, modulate mosquito hearing organs.

The Transcription Factor ATF5 Mediates a Mammalian Mitochondrial UPR
• Christopher J. Fiorese,
• Anna M. Schulz,
• Yi-Fan Lin,
• Nadine Rosin,
• Mark W. Pellegrino,
• Cole M. Haynes
Fiorese et al. identify the transcription factor ATF5 as a mediator of a mammalian mitochondrial unfolded protein response. Their investigation suggests that ATF5 communicates mitochondrial status to the nucleus to mediate the induction of a mitochondrial protective program that includes mitochondrial chaperone and protease genes.

Increasing Nitrogen Fixation and Seed Development in Soybean Requires Complex Adjustments of Nodule Nitrogen Metabolism and Partitioning Processes
• Amanda M Carter,
• Mechthild Tegeder
Legumes access atmospheric nitrogen (N) in a symbiotic relationship with bacteria that reside in root nodules. Carter and Tegeder demonstrate that enhancing N export from nodules leads to improved N fixation, shoot nutrition, and seed yield. They show that N transport out of nodules is tightly linked to nodule metabolic and partitioning pathways.

Lamin Mutations Accelerate Aging via Defective Export of Mitochondrial mRNAs through Nuclear Envelope Budding
• Yihang Li,
• Linda Hassinger,
• Travis Thomson,
• Baojin Ding,
• James Ashley,
• William Hassinger,
• Vivian Budnik
Li et al. link the nuclear envelope (NE)-budding export pathway to premature aging in fly models of progeroid syndromes induced by A-type lamin mutations. They find mitochondrial RNAs, such as mitofusin, at NE-budding sites and show that disruption of NE budding prior to adulthood results in accelerated aging and mitochondrial degeneration in adults.

Arabidopsis NAP1 Regulates the Formation of Autophagosomes
• Pengwei Wang,
• Christine Richardson,
• Chris Hawes,
• Patrick J. Hussey
Wang et al. find that constant pressure can induce NAP1 to localize to autophagosomes. The Arabidopsis nap1 mutant is defective in autophagy: it is more susceptible to nitrogen starvation and is less salt tolerant. This study shows that NAP1 has another function in plants, and that is as a regulator of autophagy.

Glutamatergic Monopolar Interneurons Provide a Novel Pathway of Excitation in the Mouse Retina
• Luca Della Santina,
• Sidney P. Kuo,
• Takeshi Yoshimatsu,
• Haruhisa Okawa,
• Sachihiro C. Suzuki,
• Mrinalini Hoon,
• Kotaro Tsuboyama,
• Fred Rieke,
• Rachel O.L. Wong
Della Santina et al. identify a new neuron type in the mouse retina. These cells (GluMIs) resemble inhibitory interneurons morphologically but make glutamatergic ribbon synapses in the inner retina. GluMIs have light-response features that are distinct from known excitatory interneurons and thus provide a novel pathway for excitation in the retina.