Editors' Choice

Science  01 Nov 2019:
Vol. 366, Issue 6465, pp. 584
  1. Ecology

    Nocturnal migration of night hunters

    1. Caroline Ash

    European nightjar (Caprimulgus europaeus) in flight at dusk

    PHOTO: JAMES WARWICK/GETTY IMAGES

    Bird migration is a vast global biannual phenomenon requiring food as fuel on a similar scale. Superimposed on these twice-yearly events are other regular occurrences, including tightly predictable lunar cycles. Norevik et al. wondered how the moon might influence migration of birds that hunt at night, such as the European nightjar Caprimulgus europaeus. These birds hunt insect prey by sight and are more active during moonlit nights, giving a monthly boost to their food intake. Using GPS-linked data loggers, the authors found that migration activity in these birds en route tends to peak after a full-moon feeding binge. The lunar cycle strongly synchronizes migration responses among individuals, which means a large proportion of a population migrates simultaneously. Such synchronized responses may make them vulnerable to climate change–related or other adverse events along their migration route.

    PLOS Biol. 10.1371/journal.pbio.3000456 (2019).

  2. Cancer

    The ABCs of brain tumor prognosis

    1. Paula A. Kiberstis

    Meningiomas are brain tumors that are typically benign and curable by surgery. In about 20% of cases, however, the tumors recur, and then patient prognosis is poor. Tumor histopathology is currently used to predict which patients might benefit from more aggressive treatment, but this method can be inaccurate. Patel et al. used clinical, gene expression, and sequencing data to classify meningiomas from 140 patients. Their analysis identified three distinct groups of tumors (A, B, and C), with type C being the most likely to recur. Type C tumors were characterized by altered activity of a protein complex that controls cell cycle progression. Importantly, this molecular classification system was a better predictor of prognosis than the method currently used in clinics.

    Proc. Natl. Acad. Sci. U.S.A. 116, 21715 (2019).

  3. Molecular Biology

    Stepping on the condensation

    1. Steve Mao

    Condensin complexes are molecular motors that extrude DNA loops in a highly conserved and adenosine triphosphate–dependent manner, essential for eukaryotic chromosome condensation during mitosis. Elbatsh et al. mutated condensin at two motor sites (AS1 and AS2). They found that mutating AS1 impairs the initiation of loop formation leading to hypocondensation, and mutating AS2 speeds up contraction of DNA and diminishes the formation of high-order, stable loop structures. AS1 and AS2 thus serve as the accelerator and brake of the condensin machine. Regulating these two opposite adenosine triphosphatase activities is important for controlling chromatin structure.

    Mol. Cell 10.1016/j.molcel.2019.09.020 (2019).

  4. Atomic Physics

    Dynamics in a box

    1. Jelena Stajic

    Cold atomic gases provide a versatile setting for the study of many-body dynamics. When interactions between atoms are strong, transport coefficients in these systems become universal functions of density and temperature. To measure the sheer viscosity of an atomic gas, experimentalists rely on studying the expansion of the gas as it is released from a trap; however, in such experiments, the hydrodynamic description breaks down at cloud edges. To avoid this complication, Baird et al. trapped a gas of lithium-6 atoms in a uniform “box” potential and studied its response to a periodic perturbation. The researchers found that, unlike in expansion experiments, the response depended on thermal conductivity. The extracted value of thermal conductivity was in agreement with theoretical calculations.

    Phys. Rev. Lett. 123, 160402 (2019).

  5. Stem Workforce

    Quantifying gender bias

    1. Melissa McCartney

    Gender biases persist in academia, but no tool that quantifies the extent of these biases currently exists. Tran et al. developed and validated the Perceived Subtle Gender Bias Index (PSGBI), designed to quantify women's perceptions of subtle biases within academia. The PSGBI contains four subscales: perceived gender inequity, collegiality, mentorship, and institutional support. The PSGBI was able to differentiate the higher perceptions of subtle gender biases by academic rank, tenured women, and women in men-dominated contexts, that is, associate and full professors perceived more inequality and biases relative to assistant professors. Moving forward, the PSGBI can provide women academics and their allies with data for further discussing gender bias as well as a set of events and experiences to understand where and when biases may be experienced.

    Psychol. Women Q. 10.1177/0361684319877199 (2019).

  6. Cell Biology

    Parasite actin in action

    1. Stella M. Hurtley

    Fluorescence microscopy image of a cluster of Toxoplasma gondii parasites

    IMAGE: KE HU AND JOHN M. MURRAY (CC BY 4.0)

    In apicomplexan parasites, such as Plasmodium or Toxoplasma species, the major function of parasite filamentous actin (F-actin) was thought to be limited to gliding motility and host cell invasion. Using live-cell imaging, Periz et al. studied transgenic parasites labeled with anti-actin camel antibodies fused to fluorescent markers. They found that Toxoplasma parasites within host cell vacuoles formed an F-actin network that connected individual parasites and was required for recycling of maternal organelles. Using similar technologies, Del Rosario et al. investigated the F-actin dynamics of apicomplexan parasites during host cell invasion. Superresolution microscopy revealed that invading parasites have perinuclear F-actin that eases passage of the parasite nucleus into the host cell. Thus, apicomplexan F-actin can form highly dynamic filaments in vivo that fulfill multiple functions during parasite development and invasion.

    Nat. Commun. 10, 4183 (2019); EMBO Rep. 2019, e48896 (2019).

  7. Organic Chemistry

    Oxygen caught amid three carbons

    1. Jake Yeston

    Oxygen rarely forms more than two bonds to carbon centers. Surrounding one oxygen with three alkyl groups produces an oxonium ion that tends to be highly reactive. In this vein, a tricyclic oxonium motif has been invoked in the biosynthetic pathways postulated for certain natural products associated with the Laurencia genus of red algae. Chan et al. prepared several of these posited intermediates by halide abstraction and characterized them directly by nuclear magnetic resonance spectroscopy at −78°C. Displacement reactions with a range of nucleophiles gave rise to 10 related natural products.

    J. Am. Chem. Soc. 141, 15951 (2019).