Editors' Choice

Science  22 Feb 2019:
Vol. 363, Issue 6429, pp. 832
  1. Microbiota

    Microbes promote gut maturity

    1. Caroline Ash

    Color-enhanced scanning electron micrograph of bifidobacteria, which predominate in the fecal microbiota of infant mammals.

    IMAGE: EYE OF SCIENCE/SCIENCE SOURCE

    Among the first organisms to colonize a newborn child's gut are bifidobacteria. These organisms are milk specialists, and their early establishment is essential for healthy human development. We are still at an early stage of understanding how the succession of microorganisms influence gut maturity, so O'Connell Motherway et al. focused attention on bifidobacterial colonization in mice, the first step of which is bacterial attachment by tight adherence pili. This is followed 5 days later by host mucosal proliferation in vivo, which is promoted by a subunit of the bacterial pilus called TadE; importantly, TadE bears no identity with mammalian growth factors. The authors propose that the bacterial pili subunits generate an extracellular protein scaffold that stimulates development of the mammalian gut mucosa.

    Mol. Microbiol. 111, 287 (2019).

  2. Diagnosis

    Next-generation prenatal screening

    1. Gemma Alderton

    Fetal DNA that is circulating in the blood of pregnant women is frequently extracted noninvasively and screened for common chromosome aneuploidies that cause disease such as trisomy of chromosome 21, which may result in Down syndrome. There are numerous other syndromes that are caused by single gene mutations that cannot be assessed like this. Zhang et al. developed a next-generation DNA sequencing approach for circulating fetal DNA that can detect alterations in 30 genes that cause monogenic disorders. Tests were performed on 422 pregnant women, and follow-up studies confirmed 20 positive results and 127 negative results, with no reported false-negative or false-positive results, suggesting that the method is highly specific and accurate.

    Nat. Med. 10.1038/s41591-018-0334-x (2019).

  3. Muscle Regeneration

    Making more youthful muscle

    1. Beverly A. Purnell

    Aging reduces the body's ability to regenerate. The myogenic potential of muscle stem cells (MuSCs) is a prime example. Recent work shows that some factors that allow us to bounce back after injury include extracellular signals from the stem cell niche. Lukjanenko et al. show that MuSC dysfunction with aging is a result of the loss of matricellar WNT1 inducible signaling pathway protein 1 (WISP1) from fibro-adipogenic progenitors (FAPs). When WISP1 is secreted from FAPs, the Akt pathway is activated along with asymmetric MuSC cell division. Eliminating mouse WISP1 results in defective myogenesis with reduced MuSCs. By contrast, injecting aged mice with WISP1 rescues MuSC function. By identifying the cells and cell-secreted factors that support repair, it should be possible to generate more youthful muscle.

    Cell Stem Cell 10.1016/j.stem.2018.12.014 (2019).

  4. Catalysis

    Boron radicals drive BN catalysis

    1. Phil Szuromi

    BN nanosheets (like BNNS-OH, shown in a scanning electron micrograph) can function as nonmetal catalysts.

    IMAGE: LIU ET AL., ACS NANO. 10.1021/ACSNANO.8B06978 (2019).

    Recent studies have shown that various morphologies of boron nitride (BN) can initiate or catalyze a number of reactions, including acetylene hydrochlorination and propane dehydrogenation, through formation of some radical species. Liu et al. performed density functional calculations indicating that boron radicals form at edge sites. They used electron spin resonance as well as vibrational and ultraviolet-visible spectroscopy to follow the quenching of 2,2-diphenyl-1-picrylhydrazyl radicals on BN nanosheets. By varying the dimensions of the nanosheets to change the number of edge sites decorated with OH or NH groups, they eliminated formation of O or N radicals as the source of reactivity. The boron radicals could generate OH radicals from H2O2 to perform an organic oxidation reaction.

    ACS Nano. 10.1021/acsnano.8b06978 (2019).

  5. Biomaterials

    More-realistic tumor models

    1. Marc S. Lavine

    The progression from two-dimensional cell cultures to three-dimensional (3D) spheroids and those based on hydrogel scaffolds has produced better models of in vivo tissues. However, adding this third dimension creates the need for vasculature and also opens opportunities for adding other aspects of the tumor microenvironment. Meng et al. show that 3D bioprinting can be used to precisely place clusters of tumor cells, stromal cells, and infused vascular cells according to their physiological functions. 3D bioprinting also enabled them to make stimuli-responsive capsules containing growth factors that allowed for spatial and time-controlled distribution of chemical cues. They used these models for preclinical screening to target immunotoxins for their anticancer efficacy.

    Adv. Mater. 10.1002/adma.201806899 (2019).

  6. Neuroscience

    Integrative states within the brain

    1. Claudia Pama

    The brain constantly integrates enormous amounts of information. While dynamically synthesizing cognitive processes as a function of an everchanging environment, the brain must stay flexible enough to adapt to continuous challenges. Shine et al. used a sophisticated computational framework to analyze functional magnetic resonance imaging data obtained during a wide range of cognitive tasks. They found a large integrative core of interconnected brain regions that processes information and optimizes cognitive performance and that also correlates with fluid intelligence. When the brain needs to work on more specific tasks, this integrative network segregates into more-specialized, regional brain activity. Altering neurotransmitter activity by pharmacological manipulation or disease could modulate these dynamics and affect cognitive performance.

    Nat. Neurosci. 22, 289 (2019).

  7. Education

    Tips for choosing academic mentors

    1. Melissa McCartney

    Having good mentors is critical in any career. In academia, most researchers train under just one or two graduate and/or postdoctoral mentors; however, little is known about how this mentorship affects the mentee's career. Liénard et al. analyzed an open-access database of 18,856 researchers to determine if graduate or postdoctoral mentors have a greater impact on trainee careers. Results show that although postdoctoral mentors were more influential in trainees' success, the breadth of training between graduate and postdoctoral mentors was also predictive. Trainees working under mentors with disparate expertise, who were then able to integrate both sets of expertise into their own work, had higher levels of academic success. Advice to future scientists: Consider mentors who will teach you diverse, yet complementary, skill sets.

    Nat. Commun. 9, 4840 (2018).