Editors' Choice

Science  28 Nov 2014:
Vol. 346, Issue 6213, pp. 1075
  1. Animal Behavior

    Up and down the raven social ladder

    1. Guy Riddihough

    Common ravens (Corvus corax) engaged in a mating behavior.

    PHOTO: © IMAGEBROKER/ALAMY

    Social hierarchies are complex, and threats abound for people and, as it turns out, for ravens, too. Massen et al. followed a group of approximately 200 individually marked ravens in the Austrian Alps. They found that strongly bonded breeding pairs at the top of the raven social hierarchy disrupted interactions between loosely bonded pairs lower in the hierarchy. They also tended to ignore nonbonded individuals located at the bottom of the hierarchy. In doing so, the higher-ranking birds may prevent the lower-status breeding pairs from rising up the hierarchy and becoming a social threat.

    Curr. Biol. 24, 2733 (2014).

  2. Vertebrate Evolution

    Turtles' breathing evolved at a turtle's pace

    1. Sacha Vignieri

    The physiology of turtle breathing differs from that of other vertebrates

    PHOTO: © ALL CANADA PHOTOS/ALAMY

    In most vertebrates, muscles associated with the lungs (intercostal muscles) work with the abdominal muscles to control breathing. In turtles, however, the rigid shell immobilizes the intercostal muscles, so only the abdominal muscles control lung expansion. How did such a major shift in an essential physiological function evolve? To find out, Lyson et al. compared extinct and extant vertebrates. The authors found that this transition proceeded slowly and began with a broadening of the ribs in a species that existed 50 million years before the first fully shelled turtle.

    Nat. Commun.10.1038/ncomms6211 (2014).

  3. Neuroscience

    Virtual reality changes neuronal firing

    1. Peter Stern

    Place cells are a type of neuron in the brain that gives you a sense of place and allows for spatial navigation. Visual cues are important for determining place cell function, but do other sensory or motor cues also play a role? To find out, Aghajan et al. compared rats navigating mazes in the real world and rats doing the same thing in virtual reality, where the only input they received was from distal visual cues. By monitoring the firing of place cells, the authors found that these cells did not perform optimally in the rats experiencing the virtual reality mazes. These results suggest that place cells need more than just visual signals.

    Nat. Neurosci. 10.1038/nn.3884 (2014).

  4. Organic Geochemistry

    Looking at lipids with lasers

    1. Nicholas S. Wigginton

    The remnants of microbial lipids preserved in sediments provide reliable records of past aquatic environments. Extracting trace amounts of these molecules from sediment cores is often tricky and requires a large amount of material, which causes the time resolution of these records to be rather coarse. Wörmer et al. used a high-resolution mass spectrometer coupled to a laser ionization source to track variations of nanogram levels of archaeal tetraethers at a resolution of ∼4 years. Tiny variations in lipid structure and abundance in sediments from the Mediterranean Sea with ages of over 10,000 years show that planktonic archaea there were strongly influenced by ∼200-year-long solar cycles.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1405237111 (2014).

  5. Gene Regulation

    Insulin secretion organized in the nucleus

    1. L. Bryan Ray

    Cells can modify gene expression by changing the spatial and physical landscape of DNA in the nucleus. This allows a gene to influence the expression of another gene that may be located several megabases down the chromosome. With this in mind and to find new genes that may influence how insulin functions, Xu et al. looked for genes that physically contacted the insulin gene in human pancreatic beta cells, cells that make and store insulin. They found that the insulin promoter contacted and regulated the ANO1 gene, located more than half a chromosome away, which encodes a calcium-activated chloride channel. Glucose increased ANO1 expression, and loss of ANO1 inhibited insulin secretion.

    Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1419240111 (2014).

  6. Microfluidics

    Sorting cells by subpopulations

    1. Marc S. Lavine

    The loss of cells from a tumor into the bloodstream creates circulating tumor cells (CTCs) that may allow a cancer to metastasize. Within this population of CTCs, a heterogeneous range of cells may exist. Mohamadi et al. have built a microfluidic device that can collect CTCs and differentiate them into distinct groups. Separation is based on the quantity of the epithelial marker EpCAM found on the surface, which may be related to the metastatic potential of the CTC. Magnetic nanoparticles that target EpCAM may cling to the cell surface, allowing the particles to be separated in controlled flow zones based on their ability to resist to the fluid flow due to magnetic attraction.

    Angew. Chem. 10.1002/ange.201409376 (2014).