This Week in Science

Science  22 Dec 2017:
Vol. 358, Issue 6370, pp. 1551
  1. Public Health

    Stemming the spread of rabies

    1. Catherine A. Charneski

    Large-scale rabies vaccination programs target domestic dogs.

    CREDIT: CHICAGO TRIBUNE/CONTRIBUTOR/GETTY IMAGES

    Rabies is still a problem in some developing countries. Zinsstag et al. examined the impact of two earlier vaccination campaigns in which ∼70% of the dogs in N'Djamena, the capital city of Chad, were vaccinated against rabies. The sequential vaccination campaigns reduced dog-to-dog and dog-to-human rabies transmission. Postcampaign reintroduction of rabies to N'Djamena appears to have occurred via unvaccinated dogs from regions surrounding the city, rather than ongoing transmission within the immunized area. Thus, mass vaccination efforts can help to stem rabies in regions afflicted by this fatal disease.

    Sci. Transl. Med. 9, eaaf6984 (2017).

  2. Economics

    Warming stresses developing countries

    1. Gilbert Chin

    Weather-induced conflicts in developing countries spill over to developed countries through asylum applications. One approach to estimating the future impacts of climate change is to look at the effects of weather fluctuations. These transient shocks can be interpreted analytically as randomly distributed treatments applied to countries around the world. Missirian and Schlenker analyzed the relation between these localized shocks to agriculture and applications by that country's migrants for asylum in the European Union. When temperatures in the source country deviated from a moderate optimum around 20°C that is best for agriculture, asylum applications increased. Thus, the net forecast is for asylum applications to increase as global temperatures rise.

    Science, this issue p. 1610

  3. Plant Science

    Timing a switch in tissue integrity

    1. Pamela J. Hines

    Peptide receptors (blue) are expressed in Arabidopsis flowers.

    CREDIT: GE ET AL.

    In plants, sperm cells travel through the pollen tube as it grows toward the ovule. Successful fertilization depends on the pollen tube rupturing to release the sperm cells (see the Perspective by Stegmann and Zipfel). Ge et al. and Mecchia et al. elucidated the intercellular cross-talk that maintains pollen tube integrity during growth but destroys it at just the right moment. The signaling peptides RALF4 and RALF19, derived from the pollen tube, maintain its integrity as it grows. Once in reach of the ovule, a related signaling peptide, RALF34, which derives from female tissues, takes over and causes rupture of the pollen tube.

    Science, this issue p. 1596, p. 1600; see also p. 1544

  4. Single-Cell Genomics

    Spatial information from NICHE-seq

    1. Laura M. Zahn

    Immune functions depend on the interactions of heterogeneous cells in a range of microenvironments in the body. Although information regarding immune cell function has been collected using single-cell RNA-sequencing methods, these techniques have traditionally lacked spatial information. Medaglia et al. describe NICHE-seq, a technique that allows the sorting and analysis of cells from within visually selected territories in transgenic mice that express photoactivatable green fluorescent protein. The method successfully identified T and B cell-specific niches in mouse lymph nodes and spleens after virus infection. The approach will allow us to bridge the gap between cellular and spatial information in studies of organs.

    Science, this issue p. 1622

  5. Floristics

    The vascular plants of the Americas

    1. Andrew M. Sugden

    Botanical exploration in the Americas has a history that stretches back for half a millennium, with knowledge assembled in diverse regional floras and lists. Ulloa Ulloa et al. present a comprehensive and integrated compilation of all known native New World vascular plant species (see the Perspective by Givnish). This compilation, in a publicly available, searchable database, includes 124,993 species—about one-third of the worldwide total. They further present details of the distribution of species across families and genera, the geographical foci of diversity, and the floristic relationships between regions. The rate of plant species discovery in the Americas averages almost 750 annually, so this valuable resource will continue to grow.

    Science, this issue p. 1614; see also p. 1535

  6. Chemical Biology

    Chemical control of transcription

    1. Steve Mao

    Friedreich's ataxia, a devastating neurodegenerative disease with no effective therapy, is caused by an expansion of intronic repeats and hence a reduced expression of the FXN gene. Erwin et al. synthesized a molecule that specifically targets the expanded repressive repeats. This molecule thereby licenses productive transcription elongation and restores FXN expression to normal levels. In the future, similar interventions may be effective in a diverse array of diseases caused by unstable expansions in microsatellite repeats.

    Science, this issue p. 1617

  7. Social Sciences

    Untangling service denial motivations

    1. Aaron Clauset

    In the United States, national debates continue about whether businesses should be allowed to deny services to specific kinds of customers for religious reasons. However, little is known about current public views on this issue. Powell et al. used a national-scale scientific survey to untangle the motivations of Americans who oppose or support a right to deny business services to minorities, including gay and interracial couples. American support for denying service to same-sex couples appears not to be driven by belief in religious freedoms, but instead by general libertarianism and personal opposition to marriage rights.

    Sci. Adv. 10.1126/sciadv.aao5834 (2017).

  8. Geophysics

    Determining damping of our plates

    1. Brent Grocholski

    For plate tectonics to operate, a weaker layer called the asthenosphere must underlie the rigid lithospheric plates. Quantifying the difference in strength comes down to how much each layer attenuates energy. Takeuchi et al. exploited an ocean-bottom seismic network and seismic energy from the 2011 Japanese Tohoku-oki earthquake to quantify the attenuation in each layer (see the Perspective by Dalton). The attenuation of energy in the asthenosphere lined up with previous estimates, but the lithospheric attenuation was roughly one-fifth as strong as that predicted by some previous models.

    Science, this issue p. 1593; see also p. 1536

  9. Neutron Star Merger

    GROWTH observations of GW170817

    1. Keith T. Smith

    The gravitational wave event GW170817 was caused by the merger of two neutron stars (see the Introduction by Smith). In three papers, teams associated with the GROWTH (Global Relay of Observatories Watching Transients Happen) project present their observations of the event at wavelengths from x-rays to radio waves. Evans et al. used space telescopes to detect GW170817 in the ultraviolet and place limits on its x-ray flux, showing that the merger generated a hot explosion known as a blue kilonova. Hallinan et al. describe radio emissions generated as the explosion slammed into the surrounding gas within the host galaxy. Kasliwal et al. present additional observations in the optical and infrared and formulate a model for the event involving a cocoon of material expanding at close to the speed of light, matching the data at all observed wavelengths.

    Science, this issue p. 1565, p. 1579, p. 1559; see also p. 1554

  10. Neutron Star Merger

    Photons from a gravitational wave event

    1. Keith T. Smith

    Two neutron stars merging together generate a gravitational wave signal and have also been predicted to emit electromagnetic radiation. When the gravitational wave event GW170817 was detected, astronomers rushed to search for the source using conventional telescopes (see the Introduction by Smith). Coulter et al. describe how the One-Meter Two-Hemispheres (1M2H) collaboration was the first to locate the electromagnetic source. Drout et al. present the 1M2H measurements of its optical and infrared brightness, and Shappee et al. report their spectroscopy of the event, which is unlike previously detected astronomical transient sources. Kilpatrick et al. show how these observations can be explained by an explosion known as a kilonova, which produces large quantities of heavy elements in nuclear reactions.

    Science, this issue p. 1556, p. 1570, p. 1574, p. 1583; see also p. 1554

  11. Immunology

    Minor infections cause big problems

    1. Seth Thomas Scanlon

    Pathogenic infection has been implicated in the chronic inflammation seen in inflammatory bowel diseases (IBDs) such as ulcerative colitis and Crohn's disease. Yang et al. show that recurrent, low-level, and fully resolving Salmonella enterica Typhimurium (ST) infections can precipitate severe colonic inflammation in mice. ST-induced TLR4 activation resulted in increased neuraminidase 3 (Neu3) production and activity in the duodenum. This led to intestinal alkaline phosphatase (IAP) desialylation and degradation. IAP deficiency caused a marked increase in commensal bacteria-generated lipopolysaccharide-phosphate in the colon, provoking inflammation. Treatment with calf IAP or the antiviral drug zanamivir (which inhibits Neu3 activity) prevented this inflammatory cascade. This pathway may serve as an effective target for future human IBD therapies.

    Science, this issue p. eaao5610

  12. Water Thermodynamics

    Pointing to a second critical point

    1. Phil Szuromi

    One explanation for the divergence of many of the thermodynamic properties of water is that there is a critical point in deeply supercooled water at some positive pressure. For bulk water samples, these conditions are described as “no man's land,” because ice nucleates before such temperatures can be reached. Kim et al. used femtosecond x-ray laser pulses to probe micrometer-sized water droplets cooled to 227 K (see the Perspective by Gallo and Stanley). The temperature dependence of the isothermal compressibility and correlation length extracted from x-ray scattering functions showed maxima at 229 K for H2O and 233 K for D2O, rather than diverging to infinity. These results point to the existence of the Widom line, a locus of maximum correlation lengths emanating from a critical point in the supercooled regime.

    Science, this issue p. 1589; see also p. 1543

  13. Plant Science

    Fungal effectors of wheat stem rust

    1. Pamela J. Hines

    The fungal pathogen Ug99 (named for its identification in Uganda in 1999) threatens wheat crops worldwide. Ug99 can kill entire fields of wheat and is undeterred by many of the disease-resistance genes that otherwise protect wheat crops. Two papers describe two peptides secreted by the fungus as it attacks the wheat (see the Perspective by Moscou and van Esse). Chen et al. show that fungal AvrSr50 binds to the plant's immune receptor Sr50, and Salcedo et al. show that fungal AvrSr35 binds to Sr35. Successful binding activates the plant's immune defenses. Removing or inactivating these Avr effectors leaves the plant defenseless and susceptible to disease.

    Science, this issue p. 1607, p. 1604; see also p. 1541

  14. Paleontology

    A treasure trove of early plant fossils

    1. Julia Fahrenkamp-Uppenbrink

    In 1917, scientists published the first detailed report on an ancient fossilized ecosystem found near the village of Rhynie in Scotland. One hundred years later, the remarkably well-preserved Rhynie Chert fossils continue to provide insights into the life cycles of early land plants. As Kenrick describes in a Perspective, the life cycles of the Rhynie Chert plants were different from those of all current land plant lineages, even those considered to be ancient, such as mosses. Comparison with results from developmental genetics reveals how shifting patterns of gene expression transformed plant life cycles.

    Science, this issue p. 1538

  15. Mucosal Immunology

    Licensing microbes for symbiosis

    1. Anand Balasubramani

    Gut microbiota have several important functions, including aiding host metabolism and limiting pathogen invasion by competing for essential nutrients. To establish and sustain this symbiotic relationship, it is vital that the host develops tolerance to gut microbial antigens early in life. Knoop et al. found that mouse gut tolerance to symbionts develops between 10 and 20 days after birth and is perfectly synchronized with the formation of goblet cell-associated antigen passages (GAPs) in the colon. These GAPs facilitate transport of bacterial antigens from the gut lumen to the lamina propria. Thus, gut microbial tolerance is restricted to microbes that colonize the colon early in life.

    Sci. Immunol. 2, eaao1314 (2017).

  16. Cancer Metabolism

    Understanding a metabolic weakness

    1. Wei Wong

    Cells use the same precursor to produce the essential amino acids methionine and cysteine. Lien et al. determined why human breast cancer cells with oncogenic mutations in the lipid kinase PI3K cannot produce methionine, a metabolic vulnerability called methionine dependency. Oncogenic PI3K mutants inhibited the expression and activity of xCT, a transporter that imports an oxidized form of cysteine, thereby limiting precursor availability for methionine synthesis. Thus, methionine restriction could potentially be used to treat breast tumors expressing oncogenic PI3K mutants.

    Sci. Signal. 10, eaao6604 (2017).