Editors' Choice

Science  25 May 2018:
Vol. 360, Issue 6391, pp. 871
  1. Hair Color

    The roots of gray hair

    1. Priscilla N. Kelly

    Premature graying of hair is related to immune function.

    PHOTO: ISTOCK.COM/NINAMALYNA

    Gray hair is an inevitable part of aging. Melanocytes are the culprit cells that slow production of the color pigments called melanin, but how and why this occurs with age largely remains a mystery. Harris et al. make a link between the immune system and premature graying. They find that the protein MITF (microphthalmia-associated transcription factor), which controls melanocyte stem cell function, also works to trigger melanocyte immune responses. Interferons normally kickstart the immune response to viral and bacterial infection, but when MITF cannot regulate interferon, hair turns gray in mouse models. These findings may shed light on why chronic illness or certain autoimmune disorders can accelerate the graying process.

    PLOS Biol. 10.1371/journal.pbio.2003648 (2018).

  2. Organometallics

    Aluminum's breakup with fluoroalkenes

    1. Jake Yeston

    Carbon-fluorine bonds are hard to break. As a result, remediation of fluorocarbon waste streams is an enduring challenge. Bakewell et al. explored C–F scission in a variety of fluorinated propene derivatives by using an unusual synthetic aluminum compound. The electron-rich compound, with Al in the +1 oxidation state, inserted into both olefinic and allylic C–F bonds to form Al(III) products that were characterized crystallographically. Theory implicated two simultaneous competing mechanisms, respectively involving stereoretentive direct oxidative addition and stereoinverting intermediacy of a metallocyclopropane.

    Angew. Chem. Int. Ed. 10.1002/anie.201802321 (2018).

  3. Gene Therapy

    Better to transfer than transfuse?

    1. Paula A. Kiberstis

    β-Thalassemia is a blood disease caused by mutations in the β-globin gene. β-Globin is a subunit of hemoglobin, an oxygen-carrying protein in red blood cells. Patients with β-thalassemia are severely anemic and require lifelong transfusions of red blood cells. In two clinical trials involving a total of 22 patients, Thompson et al. tested a gene therapy–based treatment that might eliminate the need for repeated transfusions. They isolated hematopoietic stem cells from the patients, used a lentiviral vector to transfer a “normal” copy of the β-globin gene into the cells, and then infused the modified cells back into the patients. After 26 months, the patients showed sustained expression of the transgenic hemoglobin, and nearly 70% of them no longer required transfusions.

    New Engl. J. Med. 378, 1479 (2018).

  4. Genetics

    How hosts can defeat selfish elements

    1. Laura M. Zahn

    A gene controlling Wolbachia proliferation in Nasonia wasps is under positive selection.

    PHOTO: SIMON VAN NOORT/IZIKO MUSEUMS OF SOUTH AFRICA

    Wolbachia bacterial infections are horizontally passed through the eggs of nematodes and insects and can selfishly affect reproductive outcomes, resulting in an increased number of female offspring. Because Wolbachia can affect reproduction, it has been eyed as a potential gene drive system to eliminate disease-carrying vectors, such as mosquitoes. Crossing species of Nasonia wasps that maintain differing levels of Wolbachia, Funkhouser-Jones et al. mapped a gene named Wolbachia density suppressor that controls Wolbachia proliferation within hosts. Further investigation suggested that this gene is under positive selection. This adds to our understanding of the dynamics between hosts and selfish parasites such as Wolbachia and may provide information of interest for the design of gene drive systems.

    Curr. Biol. 10.1016/j.cub.2018.04.010 (2018).

  5. Physiology

    How drinking (alcohol) affects drinking (water)

    1. L. Bryan Ray

    The hormone FGF21 (fibroblast growth factor 21) is a major regulator of drinking in mice. FGF21 is produced in the liver and links metabolic status to behavioral responses through actions in the brain. It has many effects on metabolism, including regulation of preference for sugar consumption. Song et al. found that various stresses, such as alcohol consumption or a ketogenic diet, caused increased production of FGF21 and stimulation of water drinking. Although alcohol consumption has well-known acute effects on water balance through inhibition of antidiuretic hormone action, this work shows an important role for FGF21 in stimulating water drinking after alcohol consumption. FGF21 can even suppress preference for alcohol consumption in favor of pure water.

    Cell Metab. 10.1016/j.cmet.2018.04.001 (2018).

  6. Enzyme Evolution

    Something from nothing

    1. Michael A. Funk

    Specialized enzymes often originate from the refinement of a promiscuous enzyme by evolution, rather than through the emergence of activity from an inactive protein. Chalcone isomerase (CHI) catalyzes a simple chemical reaction but emerged within a protein family whose other extant members have no known enzymatic function. Kaltenbach et al. used phylogenetic reconstruction to predict the sequence of ancestors along the course of CHI evolution. The distant ancestor of the protein family had no CHI activity, despite presenting catalytic residues within an active site–like pocket. A small number of peripheral mutations could induce CHI activity in the ancestral protein, unlocking the catalytic potential already present in the binding site.

    Nat. Chem. Biol. 10.1038/s41589-018-0042-3 (2018).

  7. Cosmology

    Simulating the future of our Universe

    1. Keith T. Smith

    The energy densities of matter and dark energy in our Universe are approximately equal at the current epoch. Testing whether this is a coincidence requires running cosmological simulations into the future, something that has generally been avoided because only the past can be observed. Salcido et al. simulated the futures of universes with and without dark energy, assessing its impact on the total star formation within each universe. The presence of dark energy has surprisingly little effect, because most stars have formed before it becomes dominant. Eighty-eight percent of all stars that will ever form in our Universe have done so already. The results suggest that the current epoch is not particularly special.

    Mon. Not. R. Astron. Soc. 10.1093/mnras/sty879 (2018).