Editors' Choice

Science  12 Jun 2020:
Vol. 368, Issue 6496, pp. 1202
  1. Genetics

    Big cat genomics

    1. Laura M. Zahn

    Gir lions are a remnant population of a few hundred northern lions, mostly found in Africa, that are just surviving in India.


    The lion may be the king of beasts, but over the past ∼14,000 years, their range has decreased substantially and many current populations are in decline. To understand the historical population genomics of lions, de Manuel et al. sequenced cave lion remains from ∼30,000 years ago, several historic specimens from extinct populations over the past ∼500 years, and samples from extant populations. From this, they were able to reconstruct relationships among lion populations over time. No evidence of gene flow between cave lions and recent lion populations was detected. Modern lion groups that diverged into northern and southern lineages show evidence of admixture, especially in extant central African populations. These data could be valuable not only because they indicate the relationships between modern and extinct populations but also because they reveal a historical level of inbreeding that could be relevant to conservation efforts.

    Proc. Natl. Acad. Sci. U.S.A. 117, 10927 (2020).

  2. Signaling

    Controlling blood flow in the liver

    1. L. Bryan Ray

    High blood pressure in the liver created by fibrosis causes serious clinical illness. Blood pressure is regulated by nitric oxide, but this is depleted if hepatic sinusoidal endothelial cells are damaged. The scaffold protein β-arrestin 2 (β-Arr2) regulates the activity of endothelial cell nitric oxide synthase (eNOS) in rodent liver. Liu et al. found that in rodents, β-Arr2, which serves several functions in G protein–coupled receptor signaling, helps to control eNOS at endothelin receptors. β-Arr2 promoted the association of another protein called GIT1 with eNOS, which activates eNOS. Apparently, β-Arr2 and other signaling components form a signalsome near the endothelin receptors, which regulates eNOS function. Disruption of this signaling contributes to the liver injury and portal hypertension that cause lethal liver disease in humans.

    Proc. Natl. Acad. Sci. U.S.A. 117, 11483 (2020).

  3. Migration

    Should I stay or should I go?

    1. Caroline Ash

    The global upheaval of seasonal bird migration is an astonishing phenomenon. The European blackcap is a species of small songbird that shows great variation in wanderlust. Delmore et al. collected DNA-sequencing data from blackcaps across their breeding range to determine the genetic basis for variations in migratory behavior. The impulse to migrate and the distance and direction of travel are encoded in small genomic regions. Polymorphisms were found in genes for transcription factors such as Clock, Npas2, and Bma1, which are associated with circadian rhythm. A few genes linked to traits as varied as hyperphagia and fat deposition, learning and memory, and wing length also appear to be under strong selection to rapidly evolve new behaviors. The suite of blackcap migratory genes is distinctive, and it appears that there are many ways to genetically program migration in birds.

    eLife 9, e54462 (2020).

  4. Nanomaterials

    Patterning nanoparticles with DNA origami

    1. Phil Szuromi

    Complementary DNA strands can be used to assemble nanoparticles through specific connections, but creating multivalent directional connections is still challenging. Xiong et al. used DNA origami—a two-dimensional open square and a three-dimensional tetrahedron framework—to position DNA linkers on nanoparticles. These molecular stamping, or MOST, frames were “inked” with single-stranded DNA that transferred onto a gold nanoparticle bound inside the frame. On release, the particles could then undergo complementary strand binding with smaller gold nanoparticles to form clusters. By using different inks within the frame, gold particles of different sizes could be assembled onto the central particle. The angles between the particles in these heterogeneous clusters could also be controlled through steric effects.

    ACS Nano. 10.1021/acsnano.0c00607 (2020).

  5. Psychology

    Procedural justice improves policing

    1. Tage S. Rai

    Research on procedural justice emphasizes the importance of treating people fairly regardless of the outcome they receive. Procedural justice strategies include increased transparency, communication, and responsiveness to civilian concerns. Wood et al. examined whether the introduction of a procedural justice training program for police officers in Chicago had an impact on encounters between police and civilians. It was found that fewer complaints were registered against officers who received the training, and trained officers were less likely to use force during civilian encounters. These findings have implications for designing scalable interventions that build police legitimacy.

    Proc. Natl. Acad. Sci. U.S.A. 117, 9815 (2020).

  6. Machine Learning

    Learning macro from micro

    1. Yury Suleymanov

    Determining atomic structural correlations in condensed-phase systems is crucial for understanding material properties and their behavior at the macroscale. It represents one of the central challenges in modern statistical mechanics because of the complex collective behavior emerging from microscopic many-body interactions. Using two classical condensed-phase models, a Lennard-Jones system and a hard-sphere fluid, Craven et al. show that machine learning methods trained on a set of optimally short molecular dynamics simulations can predict radial distribution functions with increased accuracy by an order of magnitude or even greater compared with traditional analytical approaches. The proposed methodology is general and could be applied more broadly across diverse condensed-phase systems.

    J. Phys. Chem. Lett. 10.1021/acs.jpclett.0c00627 (2020).

  7. Neuroscience

    Inositol-triphosphate receptors in axons

    1. Peter Stern

    Inositol-triphosphate (IP3) receptors regulate the intracellular calcium concentration in the somatodendritic compartment of central neurons. Whether axons also possess functional IP3 receptors and what impact their activation might have are not known. Cerebellar Purkinje cells offer an ideal model because they contain a high level of IP3 receptors. Using chromophore tags that release IP3 when irradiated, Gomez et al. found that functional IP3 receptors are present in the entire axon. Different axon regions displayed different IP3-producing pathways, and IP3 receptor activation had different consequences depending on receptor localization. For instance, IP3 receptor activation in synaptic terminals caused neurotransmitter release, and receptor activation in the axon initial segment blocked action potential firing. IP3 receptor–linked signaling pathways may therefore be important in controlling axon functions.

    Proc. Natl. Acad. Sci. U.S.A. 117, 11097 (2020).

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