[Working Life] Playing the field

Author: Gretchen Meyer

[This Week in Science] Skirting quality control to treat cystic fibrosis

Author: Leslie K. Ferrarelli

[New Products] New Products

A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.

[This Week in Science] Normal skin’s curiously abnormal genome

Author: Paula A. Kiberstis

[Report] Structure of the HIV-1 RNA packaging signal

The 5′ leader of the HIV-1 genome contains conserved elements that direct selective packaging of the unspliced, dimeric viral RNA into assembling particles. By using a 2H-edited nuclear magnetic resonance (NMR) approach, we determined the structure of a 155-nucleotide region of the leader that is independently capable of directing packaging (core encapsidation signal; ΨCES). The RNA adopts an unexpected tandem three-way junction structure, in which residues of the major splice donor and translation initiation sites are sequestered by long-range base pairing and guanosines essential for both packaging and high-affinity binding to the cognate Gag protein are exposed in helical junctions. The structure reveals how translation is attenuated, Gag binding promoted, and unspliced dimeric genomes selected, by the RNA conformer that directs packaging.
Authors: Sarah C. Keane, Xiao Heng, Kun Lu, Siarhei Kharytonchyk, Venkateswaran Ramakrishnan, Gregory Carter, Shawn Barton, Azra Hosic, Alyssa Florwick, Justin Santos, Nicholas C. Bolden, Sayo McCowin, David A. Case, Bruce A. Johnson, Marco Salemi, Alice Telesnitsky, Michael F. Summers

[This Week in Science] Increasingly rapid ice sheet melting

Author: H. Jesse Smith

[Report] Multiplex single-cell profiling of chromatin accessibility by combinatorial cellular indexing

Technical advances have enabled the collection of genome and transcriptome data sets with single-cell resolution. However, single-cell characterization of the epigenome has remained challenging. Furthermore, because cells must be physically separated before biochemical processing, conventional single-cell preparatory methods scale linearly. We applied combinatorial cellular indexing to measure chromatin accessibility in thousands of single cells per assay, circumventing the need for compartmentalization of individual cells. We report chromatin accessibility profiles from more than 15,000 single cells and use these data to cluster cells on the basis of chromatin accessibility landscapes. We identify modules of coordinately regulated chromatin accessibility at the level of single cells both between and within cell types, with a scalable method that may accelerate progress toward a human cell atlas.
Authors: Darren A. Cusanovich, Riza Daza, Andrew Adey, Hannah A. Pliner, Lena Christiansen, Kevin L. Gunderson, Frank J. Steemers, Cole Trapnell, Jay Shendure

[Introduction to Special Issue] Tara Oceans studies plankton at PLANETARY SCALE

Authors: P. Bork, C. Bowler, C. de Vargas, G. Gorsky, E. Karsenti, P. Wincker

[Report] Encouraging sanitation investment in the developing world: A cluster-randomized trial

Poor sanitation contributes to morbidity and mortality in the developing world, but there is disagreement on what policies can increase sanitation coverage. To measure the effects of alternative policies on investment in hygienic latrines, we assigned 380 communities in rural Bangladesh to different marketing treatments—community motivation and information; subsidies; a supply-side market access intervention; and a control—in a cluster-randomized trial. Community motivation alone did not increase hygienic latrine ownership (+1.6 percentage points, P = 0.43), nor did the supply-side intervention (+0.3 percentage points, P = 0.90). Subsidies to the majority of the landless poor increased ownership among subsidized households (+22.0 percentage points, P < 0.001) and their unsubsidized neighbors (+8.5 percentage points, P = 0.001), which suggests that investment decisions are interlinked across neighbors. Subsidies also reduced open defecation by 14 percentage points (P < 0.001).
Authors: Raymond Guiteras, James Levinsohn, Ahmed Mushfiq Mobarak

[Technical Response] Response to Comment on “Agriculture facilitated permanent human occupation of the Tibetan Plateau after 3600 B.P.”

Guedes et al. have drawn attention to a mismatch between the predictions of their “thermal niche model” and the records we have published of early barley finds in the northeastern Tibetan Plateau. Here, we consider how that mismatch usefully draws our attention to the additional variables that may account for it—namely, variations in genetic expression and agricultural practice.
Authors: Guanghui Dong, Dongju Zhang, Xinyi Liu, Fengwen Liu, Fahu Chen, Martin Jones