Editors' Choice

Science  15 Feb 2019:
Vol. 363, Issue 6428, pp. 704
  1. Neuroscience

    Sleeping in standby mode

    1. Claudia Pama

    Even when asleep, humans remain alert to external stimuli.

    PHOTO: ISTOCK.COM/STEPHANE NOIRET

    Sleep is essential, but it makes us unable to interact and vulnerable. Yet the sleeping brain continues to process stimuli from the environment. Legendre et al. presented awake and sleeping subjects with relevant and irrelevant stories via both ears while recording the neural responses in their brains with electroencephalography. Although sleepers seemed unresponsive, their brains clearly registered external stimuli to an extent that depended on specific brain rhythms and sleep depth. Thus, sleepers can process surrounding events sufficiently to know when it might be a good idea to rapidly wake up.

    Nat. Hum. Behav. 10.1038/s41562-018-0502-5 (2019).

  2. Cell Biology

    Chromosome axis organization

    1. Steve Mao

    The chromosome axis is a meiosis-specific structure that is essential for proper chromosome pairing and meiotic recombination. It is conserved among all eukaryotes; however, the key axis protein components are evolutionarily divergent among different species. West et al. characterized axis proteins in baking yeast, a mustard plant, and human. Although these proteins have little sequence homology, they all form filaments from tetrameric units and recruit key players that mediate downstream meiotic recombination. This common assembly feature ensures that the architecture of the meiotic-chromosome axis is highly conserved across fungi, mammals, and plants.

    eLife 8, e40372 (2019).

  3. Cell Biology

    Tunneling nanotubes under the microscope

    1. Stella M. Hurtley

    Long, actin-rich membranous protrusions called tunneling nanotubes (TNTs) allow the intercellular transport of various cargos, including viruses, organelles, and proteins. Sartori-Rupp et al. report the structural characterization of TNTs formed between neuronal cells in culture using correlative light- and cryo–electron microscopy approaches. They found that TNTs are distinct from other actin-rich cell protrusions like filopodia. TNTs are composed of a bundle of functional individual tunneling nanotubes containing membrane-bound compartments, including mitochondria. Bridging threads between the individual nanotubes contained the cell adhesion molecule N-cadherin.

    Nat. Commun. 10, 342 (2019).

  4. Organic Chemistry

    Illuminating a path uphill to open rings

    1. Jake Yeston

    When a chemical compound absorbs light directly, it gets a burst of energy that can propel an otherwise unfavorable reaction forward. In principle, light-absorbing catalysts can likewise channel energy to substrates to push reactions uphill thermodynamically. Nonetheless, the recent surge in photoredox catalysis has largely focused on accelerating favorable transformations. Ota et al. demonstrate that a catalyst system composed of an iridium photoredox chromophore, a phosphate base, and a thiol for hydrogen-atom transfer can isomerize cyclic alcohols to higher-energy linear aldehydes. The high-yielding protocol is compatible with a wide variety of complex substrates.

    J. Am. Chem. Soc. 141, 1457 (2019).

  5. Alzheimer's Disease

    Targeting Tau

    1. Lisa D. Chong

    Cholesterol metabolism is linked to Alzheimer's disease (AD) pathogenesis; however, the pathways involved are only partially understood. Van der Kant et al. associated cholesterol with the accumulation of phosphorylated Tau (pTau) protein in neurons, a hallmark of AD. The study screened compounds for the ability to block pTau accumulation in neurons that were derived from AD patients. Drugs that decreased cholesteryl esters (CEs) also reduced pTau. The effective drugs included statins, which block cholesterol synthesis, and drugs that alter the metabolism of cholesterol into CEs or 24-hydroxycholesterol. Reducing neuronal CEs was associated with increased proteasome-mediated degradation of pTau.

    Cell Stem Cell 10.1016/j.stem.2018.12.013 (2018).

  6. Electron Diffraction

    Microsolution for macromolecules

    1. Michael A. Funk

    Macromolecular protein crystals can be prepared for microcrystal electron diffraction by using focused ion beam milling.

    IMAGE: M. MARTYNOWYCZ ET AL., STRUCTURE, 10.1016/J.STR.2018.12.003 (2019)

    Protein crystallographers who hope to use x-ray diffraction to determine structures have long struggled with growing large, uniform protein crystals. Crystals only a few micrometers thin are ideal for diffraction by electrons but are likewise hard to grow predictably. Focused ion beam milling can create thin slices from large protein crystals that are ideal for electron diffraction. Martynowycz et al. demonstrate that continuous rotation of a single crystal section with careful control of electron dose can yield a high-resolution structure of a model protein. Such a strategy should be generally applicable to otherwise intractable microcrystals, which are, as of now, a common dead end.

    Structure 10.1016/j.str.2018.12.003 (2019).

  7. Astrochemistry

    Molecules in interstellar space

    1. Keith T. Smith

    Chemistry in space occurs wherever gas is dense and cool enough for chemical bonds to form, producing a wide variety of molecules. These are particularly common in the gas clouds that provide the raw material for star and planet formation. McGuire has cataloged all molecules detected in the interstellar and circumstellar medium. More than 200 distinct molecules have been found, increasing at an average rate of four or five per year. The inventory of known molecules is heavily biased toward those that are easy to observe with radio telescopes. Thousands of astronomically observed molecular lines remain unassigned, often because of a lack of laboratory spectroscopy for comparison.

    Astrophys. J. Suppl. Ser. 239, 17 (2018).

  8. Plant Science

    Optimizing agricultural fertilization

    1. Pamela J. Hines

    Although potassium (K) is the seventh-most-abundant element in Earth's crust, mineable resources of bioavailable K are finite. Plants depend on K for growth and development, but most K in soil is inaccessible to them. Dhillon et al. calculated the K use efficiency for cereal crops worldwide over a 55-year span and found that yields in recent decades have increased faster than the addition of new land for cultivation. This is due in part to the increased use of fertilizers that include K; however, K use efficiency has not improved. What is needed is fin=e-scale analysis of bioavailable K in agricultural fields, attention to the soil microbiome, and avoiding oversupply of K.

    Agron. J. 10.2134/agronj2018.07.0462 (2018).