Editors' Choice

Science  20 Nov 2020:
Vol. 370, Issue 6519, pp. 927
  1. Light Pollution

    Too bright to breed

    1. Sacha Vignieri

    Night light from coastal cities overpowers natural signals for coral spawning from neighboring reefs.

    PHOTO: NOKURO/ALAMY STOCK PHOTO

    Most coral species reproduce through broadcast spawning. For such a strategy to be successful, coordination has had to evolve such that gametes across clones are released simultaneously. Over millennia, lunar cycles have facilitated this coordination, but the recent development of bright artificial light has led to an overpowering of these natural signals. Ayalon et al. tested for the direct impact of different kinds of artificial light on different species of corals. The authors found that multiple lighting types, including cold and warm light-emitting diode (LED) lamps, led to loss of synchrony and spawning failure. Further, coastal maps of artificial lighting globally suggest that it threatens to interfere with coral reproduction worldwide and that the deployment of LED lights, the blue light of which penetrates deeper into the water column, is likely to make the situation even worse.

    Curr. Biol. 10.1016/j.cub.2020.10.039 (2020).

  2. Signal Transduction

    How RAS mutations really work

    1. L. Bryan Ray

    Mutations in the small guanosine triphosphatase RAS occur in many human tumors and are thought to act by activating the mitogen-activated protein kinase (MAPK, also called ERK) signaling pathway. Gillies et al. used imaging of live single cells to measure MAPK activity in cells expressing a single wild-type or mutant isoform of human RAS. The dynamic range of the signaling pathway and its growth factor responsiveness were surprisingly unperturbed. Although RAS mutants are biochemically more active, negative feedback and other regulatory mechanisms still exert control. The oncogenic effects of RAS mutations could reflect a small increase in baseline activity of the pathway. RAS mutations may be common in cancer in part because they can be constrained and thus do not lead to cell death.

    Mol. Syst. Biol. 16, e9518 (2020).

  3. Infectious Disease

    Undercover parasites

    1. Gemma Alderton

    The rainy season in Mali is the trigger for mosquito breeding and transmission of persistent infections of human malaria parasites.

    PHOTO: ANDREW AITCHISON/ALAMY STOCK PHOTO

    The protozoan Plasmodium falciparum is transmitted from mosquitoes to humans, where it replicates in red blood cells to cause malaria. In many countries where malaria is endemic, most transmission occurs during the rainy season, so how does the parasite persist during the dry season? Andrade et al. analyzed P. falciparum from the blood of Malian individuals during the dry season and found that they had low numbers of parasites and no symptoms. Compared with the febrile cases that occur during the rainy season, parasites in asymptomatic infections exhibit distinct gene expression patterns and reduced binding to the endothelium lining blood vessels. Asymptomatic cases also show longer circulation and continual clearance of infected red blood cells by the spleen. Such low-level infections do not stimulate an acute immune response and can persist until the next transmission season, when mosquitoes can breed and resume transmission.

    Nat. Med. 10.1038/s41591-020-1084-0 (2020).

  4. Transposons

    Transposable drivers or passengers?

    1. Laura M. Zahn

    Transposable element activity has been associated with cancer genomes, but whether this activity drives cancers or is incidental to tumorigenesis has been difficult to resolve. Tiwari et al. tested the function of the oncogene p53 on LINE1s, transposable elements found in human cells. Oncogene p53 stimulates repressive histone marks on LINE1s, which keeps them from replicating. If p53 becomes mutated in human cells, the epigenetic repressors on the LINE1s are not maintained. This allows LINE1s to become hyperactivate and replicate within the genome. In some cases, this causes chromosomal breakage, a hallmark of p53 loss-of-function cancers, and stimulates inflammation. Thus, when function is lost in p53 mutants and LINE1 activity increases, an acute oncogenic crisis looms.

    Genes Dev. 34, 1439 (2020).

  5. Physics

    Testing an exotic magnet

    1. Jelena Stajic

    In quantum spin liquid (QSL), an exotic state of matter predicted to occur in certain materials, spins remain in a liquid-like state down to the lowest temperatures. A theoretical realization of a QSL is the Kitaev model, where spins reside on a two-dimensional hexagonal lattice. The layered material RuCl3 is thought to display the Kitaev model physics. Modic et al. studied magnetic anisotropy in RuCl3. They focused on the magnetotropic coefficient, which reflects the rigidity of a material to rotation in a magnetic field. In a certain temperature range, the coefficient scaled linearly with the magnetic field, indicating that the relevant energy scales were those set by temperature and magnetic field rather than by magnetic interactions intrinsic to the material.

    Nat. Phys. 10.1038/s41567-020-1028-0 (2020).

  6. Organometallics

    A crystallographic conundrum

    1. Jake Yeston

    X-ray crystallography is often construed as the most direct means of characterizing molecular structure. Nonetheless, it still relies on an accurate assessment of elemental composition to begin with. Amemiya et al. report a strange case in which a structure previously assigned to a cadmium carbonyl compound appears much more consistent with a rhenium carbonyl. Although the initial refinement statistics seemed reasonable, the ratio of displacement parameters for the metal versus the ligand atoms was unusually small. The authors further concluded that coordinative carbon and chlorine sites in the ligands were more likely to be nitrogen and sulfur, respectively.

    Chem. Sci. 10.1039/d0sc04596a (2020).

  7. Peptide Toxins

    Redirecting a wasp's sting

    1. Michael A. Funk

    Venomous animals typically produce peptides and proteins that have potent biological activities through their interaction with membranes or cellular targets. Silva et al. analyzed the sequence and structure of a short peptide toxin from the wasp Vespula lewisii and reengineered it into an antimicrobial peptide. Modifications to the end of the peptide reduced toxicity to mammalian cells while preserving the ability to disrupt the outer membrane of Gram-negative bacteria. Antimicrobial activity in mouse infection models demonstrated promising potential for the original design and various analogs.

    Proc. Natl. Acad. Sci. U.S.A. 117, 26936 (2020).

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