Editors' Choice

Science  13 Mar 2015:
Vol. 347, Issue 6227, pp. 1214
  1. Cancer Immunology

    Tumors use bacteria to hide away

    1. Kristen L. Mueller

    Fusobacterium nucleatum can inhibit anti-tumor immunity

    PHOTO: DENNIS KUNKEL MICROSCOPY, INC./VISUALS UNLIMITED, INC.

    Although bacteria can help the immune system wage war against cancer, they can play for the other side, too. Gur et al. reveal one such example for the bacterium Fusobacterium nucleatum, which is found in human tumors such as colon adenocarcinomas. A protein on the bacteria (Fap2) binds to an inhibitory receptor called TIGIT expressed on the surface of natural killer cells and T cells, reducing their ability to kill bacteria-associated tumor cells in culture. Whether F. nucleatum plays a similar role in people with colon adenocarcinomas remains to be determined.

    Immunity 42, 344 (2015).

  2. Structural Immunology

    Disarming a cellular defense system

    1. Valda Vinson

    Macrophages are cells that engulf and destroy foreign substances in a process called phagocytosis. Lee et al. now show how a bacterium from the Yersinia family, which includes the bacteria that causes bubonic plague, acts to disable phagocytosis. Yersinia enterocolitica injects a protein called YopO into macrophages. A crystal structure shows that YopO binds to single host actin proteins in a way that prevents them from adding to actin filaments that form the skeleton of the cell. Moreover, the complex sequesters and phosphorylates proteins required for remodeling the actin skeleton, probably preventing the remodeling required for phagocytosis.

    Nat. Struct. Mol. Biol. 10.1038/nsmb.2964 (2015).

  3. Materials Science

    Patterned pockets for preparing particles

    1. Marc S. Lavine

    The functional properties of multiphasic micro- and nanoparticles are critically dependent on their geometry and chemistry. Kobaku et al. developed a versatile platform for templating particles based on surface wetting. Films of silanized titanium dioxide were patterned using an ultraviolet light to give regions with high or low receding contact angles. When the templates were dip-coated into solutions containing polymers or particles, they would deposit only in the patterned areas. It was also possible to spin-coat or spray-coat the solution, and multiple deposition cycles made it possible to create particles with mixed or layered compositions. The particles are released from their templates through the use of a sacrificial interface layer, and the templates could be reused up to 20 times.

    Appl. Mat Interf. 10.1021/am507964k (2015).

  4. Stem Cells

    Ribosomes regulate stem cell fate

    1. Laura M. Zahn

    Structure of the eukaryotic 80S ribosome, indicating areas where ribosomal protein genes were deleted

    IMAGE: S. FORTIER ET AL., PNAS 112, 7 (17 FEBRUARY 2015) © 2015 NATIONAL ACADEMY OF SCIENCES

    The use of stem cells in regenerative medicine holds enormous therapeutic potential. However, scientists still need to fully understand the molecular signals that control the ability of stem cells to self-renew and differentiate. To identify genes that many regulate this, Fortier et al. screened a library of mouse embryonic stem cells (ESCs) containing chromosomal deletions. They found that the loss of a single copy of several genes encoding protein subunits of the ribosome, a large protein complex that translates mRNA into proteins, resulted in impaired ESC differentiation but did not affect self-renewal.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1418845112 (2015).

  5. Geophysics

    Piling on the magnetic field reversals

    1. Brent Grocholski

    The height of the dense chemical piles lying on the top of Earth's core may determine whether the magnetic field reverses polarity slowly or quickly. Amit and Olson try to explain changes in the frequency of field reversals found in the rock record by considering the thickness of these large lower mantle piles. Thicker piles allow more heat to flow out of the liquid metal core, which stimulates polarity reversals in the magnetic field. Thinner piles suppress heat flow and could explain the occasional long periods of stable magnetic field polarity found in the geologic record.

    Earth Planet Sci. Lett. 10.1016/j.epsl.2015.01.013 (2015).

  6. Colloidal Materials

    How surface charge changes assembly

    1. Phil Szuromi

    The surfaces of colloidal particles can be made asymmetric, such as Janus particles, which can have both hydrophobic and hydrophilic faces. Recently, a method has been developed that can symmetrically decorate a polystyrene colloidal particle with two, three, or four patches bearing charged sulfonate groups. Song et al. show that these particles can pack into unanticipated structures under the influence of an alternating current electric field. Two-patch particles formed multilayers with lower symmetry than the close-packed face-centered cubic packing of uncharged colloids. Three-patch particles formed low-symmetry chains that could pair to create double-helix sections with higher symmetry.

    J. Am. Chem. Soc. 10.1021/ja5127903 (2015).

  7. Neuroscience

    When cognitive control shuts down

    1. Peter Stern

    Photos of untidy rooms were used to elicit OCD symptoms in the subjects of this study

    IMAGE: © PETER MAHER/ALAMY

    People with obsessive-compulsive disorder (OCD) cannot control their thoughts, engage in compulsive actions and perform repetitive behaviors to reduce their anxiety. To better understand the neurological basis of these symptoms, Banca et al. used individually tailored stimuli to provoke and alleviate symptoms in people with OCD while scanning their brains with functional magnetic resonance imaging. When provoked, the caudate-prefrontal brain circuits involved in cognitive control and goal-directed behavior shut down in OCD patients. This was accompanied by hyperactivation of a brain region called the putamen, which controls repetitive behavior. These insights may pave the way for novel therapeutic approaches to treating OCD.

    Brain 138, 798 (2015).