Editors' Choice

Science  09 Nov 2018:
Vol. 362, Issue 6415, pp. 652
  1. Ophthalmic Imaging

    Making vision clearer

    1. Ian S. Osborne

    A handheld device should greatly expand the application of adaptive optics scanning laser ophthalmoscopy.

    PHOTO: CARMELO GERACI/GETTY IMAGES

    Adaptive optics scanning laser ophthalmoscopy (AOSLO) is now a routine tool used by eye care professionals to aid the detection and diagnosis of retinal disease. These machines, however, are large and not portable, so the patient needs to travel to where they are located. By combining computational algorithms with developments in miniaturized deformable mirrors and microelectromechanical technology, DuBose et al. have developed a handheld AOSLO device that weighs less than 200 grams. Such a technological development opens up the possibility of examination to a broader range of patient populations, such as children and the physically incapacitated. The light weight of the device also offers the opportunity to provide examinations to people in geographically remote areas.

    Optica 9, 1027 (2018).

  2. Neuroscience

    Decisions and their future implications

    1. Peter Stern

    We constantly make choices. It is often important to consider not only the short-term but also the longer-term implications of a choice, also known as its prospective value. In a combined decision-making and brain-scanning study, Kolling et al. found that when humans make sequential decisions, they do not only consider their immediately available options. Instead, they incorporate the average value of future options, their variability, and the time frame or search horizon, as well as search costs. Furthermore, humans even consider individual capacities and preferences for making decisions in the future. Brain activity in the dorsal anterior cingulate cortex represents prospective value, but when there is an increased need to overcome costs, activity in the ventral striatum and perigenual anterior cingulate cortex is more strongly coupled.

    Neuron 99, 1069 (2018).

  3. Cell Biology

    The intraflagellar transport train

    1. Stella M. Hurtley

    Assembly of the cilium requires bidirectional intraflagellar transport (IFT) of building blocks along microtubules to and from the site of assembly at its tip. Dynein-1b motors are required to power retrograde transport and are believed to reach the ciliary tip by kinesin-2–driven anterograde IFT. It is unclear which mechanism prevents a tug-of-war between these oppositely directed microtubule motors. Jordan et al. used cryo–electron tomography to examine the architecture of IFT trains in Chlamydomonas cilia in situ. Their findings revealed the relative positions of IFT motors on anterograde versus retrograde trains. Dynein-1b in its autoinhibited form was an integral part of anterograde trains but is positioned to prevent premature engagement with the microtubules. Once at the cilia tip, the dynein converted into its activated form, engaged the microtubules, and then powered retrograde transport.

    Nat. Cell Biol. 20, 1250 (2018).

  4. Climate Change

    Uneven results

    1. H. Jesse Smith

    Climate change will exacerbate the unevenness of precipitation.

    PHOTO: NITICHUYSAKUL PHOTOGRAPHY/GETTY IMAGES

    What are likely to be the specific results of anthropogenic activities on climate, beyond higher temperatures? One may be change in the way rainfall is distributed in time. Rainfall is an uneven phenomenon: There are wet days and dry days, floods and droughts, and hard rains and gentle rains. Pendergrass and Knutti use observations and models to show that climate change should only exacerbate that unevenness. Today it takes an average of 12 days for half of the annual rain to fall, but in a rainier, high–greenhouse gas emissions world, half the increase in precipitation should occur in only the wettest 6 days.

    Geophys. Res. Lett. 10.1029/2018GL080298 (2018).

  5. Immunometabolism

    A role for mastocytes in ketosis

    1. Seth Thomas Scanlon

    Ketogenesis is a fundamental biochemical process occurring mainly in liver mitochondria. This pathway provides energy to vital organs when access to glucose is limited for prolonged periods, such as during fasting. Lipolysis-derived fatty acids normally initiate this process via the transcription factor PPAR-α. Misto et al. found that fasting stimulates mast cells to release histamine, which stimulates the biosynthesis of the high-affinity PPAR-α agonist oleoylethanolamide via G protein–coupled H1 receptors. Thus, mast cells, recognized for their role in allergy and anaphylaxis, unexpectedly take part in the regulation of a major metabolic pathway. Future studies will be needed to uncover the underlying mechanisms of this process and understand how it may contribute to metabolic dysfunction.

    Cell Metab. 10.1016/j.cmet.2018.09.014 (2018).

  6. Superconductivity

    Thermal transport to the rescue

    1. Jelena Stajic

    The pseudogap phase in cuprate superconductors remains one of the most puzzling aspects of these materials. To shed light on the nature of the pseudogap, Michon et al. studied thermal transport in the cuprate La1.6-xNd0.4SrxCuO4. By applying magnetic fields high enough to destroy superconductivity and approaching absolute zero temperature, the researchers found that the thermal and charge transport in the pseudogap phase were locked in step. This indicates that the ground state of the nonsuperconducting pseudogap phase has the character of a conventional metal. Comparison to the data at zero field further suggests that applying magnetic fields does not affect some of the signatures of the pseudogap phase.

    Phys. Rev. X 8, 041010 (2018).

  7. Molecular Imaging

    Revealing chromosome features

    1. Steve Mao

    Cryo–electron tomography (cryo-ET) is used to visualize cellular structures in the native environment without chemical fixation and dye labeling. Cai et al. used cryo-ET on both interphase and mitotic fission yeast cells to explore some interesting features of chromosome organization. Nucleosomes in situ do not appear to resemble the canonical conformation obtained by crystallography in vitro. In vivo, it appears that nucleosomes are partially unwrapped. Moreover, nucleosomes cluster irregularly, with the clusters being more condensed and less dynamic in mitotic cells. Yet, the condensation in mitotic chromosomes is uneven, and there are loosely packed regions where, possibly, mitotic transcription occurs.

    Proc. Natl. Acad. Sci. U.S.A. 115, 10977 (2018).

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