Editors' Choice

Science  28 May 2021:
Vol. 372, Issue 6545, pp. 930
  1. Marine Ecology

    Seagrass offsets acidification

    1. Andrew M. Sugden

    Seagrass beds consume carbon dioxide and thereby reduce local seawater acidification.

    PHOTO: NOAA PHOTO LIBRARY/FLICKR/CC BY

    Gradual acidification of the world's oceans is driven by the uptake of carbon dioxide. This feature of contemporary climate change has potential consequences for marine life and the functioning of marine ecosystems. Ricart et al. show that acidification can be locally slowed or ameliorated by seagrass meadows, where uptake of carbon dioxide by the plants exceeds that produced by respiration. Along 1000 kilometers of Californian coastal waters and measured over 6 years, pH was elevated in most of the seagrass sites examined compared with adjacent sites. These findings add to the potentially beneficial suite of effects of the presence of seagrasses and macroalgae in coastal waters and indicate possible routes for the management of acidification in these systems.

    Glob. Change Biol. 27, 2580 (2021).

  2. Education

    Bringing cultural awareness to mentoring

    1. Melissa McCartney

    Mentoring is a critical component for retaining diverse talent in the STEM field. However, despite their best intentions, mentors may be unaware of how racial or ethnic differences may influence their mentees' research experience. To further investigate this potential disparity, Byars-Winston and Butz developed a scale to assess cultural diversity awareness related to race and ethnicity in research-mentoring relationships informed by multicultural counseling theory and social cognitive theory. Instrument validity yielded a three-factor mentor scale assessing attitudes, behavior, and confidence and a two-factor mentee scale assessing attitudes and behavior. This scale can be used as a self-assessment to prompt mentors' reflection on their mentoring practices and to encourage new ways of acknowledging and appreciating cultural diversity in their research-mentoring relationships.

    CBE Life Sci. Educ. 10.1187/cbe.19-06-0127 (2021).

  3. Climate Change

    Tusk records

    1. Sacha Vignieri

    Understanding how climate change may affect Arctic species is challenging given that change has been gradual. The impact of environmental transition is reflected in dietary shifts of species at upper trophic levels. Narwhals provide a unique opportunity to track wider ecological change in the Arctic because modifications in their diets can be detected using isotope analysis of the dentine deposited over their lifetimes in their elongated tusks. Dietz et al. measured isotope ratios in the tusks of 10 male narwhals collected between 1962 and 2010. The data revealed patterns consistent with dietary shifts from ice-associated (sympagic) to open-water (pelagic) food species over that time. Further, mercury levels were found to increase with the trophic level of prey, as might be expected. However, in recent decades, mercury levels in narwhals' tissues rose sharply, possibly reflecting an environmental source–related change.

    Curr. Biol. 31, 2012 (2021).

  4. Clinical Psychology

    Culture and posttraumatic stress

    1. Tage S. Rai

    A warrior from the Turkana tribe of northern Kenya

    PHOTO: CHRISTOPHER FURLONG/STAFF/GETTY IMAGES

    It is unclear whether posttraumatic stress disorder (PTSD) is a universal response to violence found everywhere or if it is culturally specific to certain parts of the world. Zefferman and Mathew interviewed warriors among the Turkana, a population of subsistence pastoralists living in Kenya. Compared with a sample of American military servicemembers who had been treated for PTSD, Turkana were equally likely to experience reactive symptoms such as hypervigilance, which may be more sensitive to experiences of danger, but they were less likely to experience depressive symptoms such as detachment and loss of interest, which may be related to feelings of moral violation. These findings suggest that symptoms of PTSD directly tied to dangers of combat may be universal, whereas the symptoms tied to the morality of combat may be more culturally variable.

    Proc. Natl. Acad. Sci. U.S.A. 118, e2020430118 (2021).

  5. Microbiology

    Actin to trap bacteria

    1. Valda Vinson

    Salmonella bacteria cause tens of millions of cases of food-related illnesses every year. On infecting host cells, the bacterium injects virulence factors that induce rearrangements of the cytoskeleton to allow internalization inside a Salmonella-containing vacuole (SCV). Here, the bacteria replicate protected from the host immune system. Hahn et al. show that although the actin network is hijacked to allow bacterial entry, it is also part of a cellular defense system. Through proteomics analysis, the authors identified the kinase SIK2 as a central player in coordinating actin defenses. During bacterial infection, SIK2 is recruited to the SCV together with proteins involved in actin polymerization. SIK2 depletion allows the escape of bacteria from the SCV, which results in collapse of cortical actin structures. Thus, SIK2 coordinates an actin network that limits intracellular proliferation of Salmonella.

    Proc. Natl. Acad. Sci. U.S.A. 118, e2024144118 (2021).

  6. Aging

    Live fast, die young

    1. Beverly A. Purnell

    Aging sees many physiological changes. Studies are revealing the dynamics of the cells and molecular factors that contribute to the aging process. For example, chronological age can be estimated by comparing DNA methylation status. Anderson et al. measured DNA methylation in the baboons of Kenya's Amboseli National Park to find out whether epigenetic changes associated with aging are affected by an animal's social environment in the wild. Early adversity and social bonds did not apparently affect the epigenetic clock, but there was a signal from male social status and competitiveness. By measuring the accumulation of epigenetic markers, high-ranking dominant males appeared older than their chronological ages.

    eLife 10, e66128 (2021).

  7. Polymer Chemistry

    Light frees a reactive thiol

    1. Phil Szuromi

    Postsynthetic modification of polymers can be aided by the release of a caged reactive group after synthesis. Rodrigues et al. report on the photorelease of a thiol group that can undergo Michael addition. Visible light causes o-thiopyrinidylbenzaldehyde to undergo a ring opening that exposes a reactive aromatic thiol group that can undergo Michael reaction with electron-deficient alkenes and alkynes in a variety of solvents. They show that a polyethylene glycol bearing a terminal alkyne group could be ligated through an esterification reaction.

    J. Am. Chem. Soc. 10.1021/jacs.1c03213 (2021).

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