Editors' Choice

Science  15 Apr 2016:
Vol. 352, Issue 6283, pp. 305
  1. Biomaterials

    Shaping cells to mature together

    1. Marc S. Lavine

    Engineered tissue resembling the stapes, a middle-ear bone.

    PHOTO: ERIK VRIJ

    Tissue engineering requires the use of degradable scaffolds that provide temporary support and an architectural guide that controls the initial growth and proliferation of seeded cells to form a desired tissue. Vrij et al. develop a more general approach in which cellular aggregates progressively fuse and assemble to form tissues. By controlling the general shape of the well into which the cells or clusters are seeded, they introduce anisotropy into both the shape of the growing objects and in deformation upon compaction. This encourages the formation of a primitive vasculature and self-scaffolding as the final tissue is assembled from the smaller building blocks.

    Adv. Mater. 10.1002/adma.201505723 (2016).

  2. Memory Research

    A pathway for forgetting

    1. Peter Stern

    Memories tend to fade over time. We still only partially understand the processes that underlie this erosion of long-term memory. Migues et al. infused two synthetic peptides that slow down the activity-induced synaptic removal of a specific type of glutamate receptor into the rat dorsal hippocampus. This procedure prevented the forgetting of specific forms of spatial memory but did not block the acquisition of new object location memories. It also prevented the generalization of contextual fear. Infusion of one these peptides into a different brain area preserved extinction memory because it inhibited time-dependent spontaneous recovery of extinguished auditory fear.

    J. Neuroscience 36, 3481 (2016).

  3. Structural Biology

    Herpes virus opens up

    1. Valda Vinson

    Two forms of glycoprotein B facilitate interface of herpes simplex virus 1 with host cells.

    PHOTO: ZEEV-BEN-MORDEHAI ET AL., PNAS (2016) © 2016 NATIONAL ACADEMY OF SCIENCES

    Herpes simplex virus 1 (HSV-1), the cause of cold sores, is an enveloped virus that uses glycoprotein B (gB) to fuse with host cells. Zeev-Ben-Mordehai et al. used electron cryotomography to determine the structure of gB in a native membrane. They found two conformations: One, the known trimeric postfusion conformation, has fusion loops close together and proximal to the membrane. The other is a more compact trimer with fusion loops distal to the membrane and splayed apart. The new conformation explains antibody and mutagenesis data that could not be rationalized on the basis of postfusion structure. It is likely a prefusion or intermediate conformation that may be a target for antivirals.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/PNAS.1523234113 (2016).

  4. α-Synuclein Toxicity

    Viewing a killer in action

    1. Stella M. Hurtley

    The pathological deposition of aberrant protein aggregates and fibrils is associated with a variety of neurodegenerative disorders. The protein α-synuclein is implicated in Parkinson's disease. Pinotsi et al. used super-resolution imaging to visualize α-synuclein as it formed aggregates in neuronal cells in culture. First they introduced pre-formed fibrils of α-synuclein and saw the endogenous soluble protein adding onto the fibrils. This process did not seem to harm the cells; however, when they added exogenous monomeric α-synuclein, it formed aggregates within the cells, which killed them. Thus, a-synuclein fibrils seem to be protective rather than harmful to neurons—at least in culture.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1516546113 (2016).

  5. Education

    The evolution of teaching evolution

    1. Melissa McCartney

    Current research in evolution encompasses more than natural selection. However, evolutionary mechanisms other than natural selection are not always presented in classrooms. Price and Perez analyzed evolution education literature and high-school and college education standards to highlight the lack of concepts such as genetic drift, dominance in allelic pairs, and evolutionary developmental biology. They analyzed students' answers on concept inventories and found that students favor natural selection as the explanation for all evolution, which may ultimately impede their understanding of additional evolutionary mechanisms. The proposed solution, interleaving the teaching of natural selection with other evolutionary processes through iterative cycles of natural selection, genetic drift, dominance, etc., could result in students having a stronger understanding of all evolutionary processes.

    Am. Biol. Teach. 10.1525/abt.2016.78.2.101 (2016).

  6. Biofuels

    Liquid fuel flows from gas streams

    1. Nicholas S. Wigginton

    Renewable resources can directly replace fossil fuels for generating electricity, but finding a cleaner replacement for liquid fuels is less clear. Biofuels have shown potential, but the cost of feedstocks, competition with land for food crops, and the overall carbon balance have hindered their progress. Hu et al. integrated two bioreactors to turn syngas—a mixture of CO2, CO, and H2—into lipids that can be used as biodiesel. Although carbon from syngas accounts for just over half of the carbon in the lipids produced, further optimization and recycling of CO2 between bioreactors should improve the net carbon balance of the system.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1516867113 (2016).

  7. Plant Science

    Know when to hold 'em…

    1. Pamela J. Hines

    During cell division, cohesins keep replicated sister chromatids attached until they segregate into separate daughter cells. This cohesion is stabilized by chromosome transmission fidelity 7 (Ctf7) protein and destabilized by the Wings apart-like (Wapl) protein. Inactivation of Ctf7 results in poorly condensed chromosomes, whereas inactivation of Wapl results in chromosomes that won't let go. De et al. investigated the interaction of cohesion, Wapl, and Ctf7 in Arabidopsis plants. Inactivation of Wapl is lethal to animal cells but has divergent effects on plant cells, so that meiosis and germ cell development are more affected than is vegetative plant growth. The results hint at an as-yet-unidentified system to regulate sister-chromatid cohesion during mitosis.

    Plant Cell 28, 521–536 (2016).

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