- Mammalian Evolution
A window into the past
- Sacha Vignieri
Pen-tailed tree shrew gives us a glimpse of one of our earliest ancestors
PHOTO: JOSEPH WOLF, PROCEEDINGS OF THE ZOOLOGICAL SOCIETY OF LONDON
Tree shrews are often held up as being living fossils, presumably very similar to our own earliest primate ancestor. The dearth of actual fossils of these small tropical mammals, however, has meant that much of this conclusion has been speculative. Li and Ni describe a new fossil tree shrew that is exceedingly similar to the extant pen-tailed tree shrew (Ptilocercus lowii), yet twice as old as any previously described sister taxa. The fossil suggests that this tree shrew has gone nearly unchanged since the Oligocene (over 34 million years ago). Further, it supports the suggestion that the extant P. lowii gives us a living glimpse of the first ancestor of the Archonta, our own superordinal group.
Sci. Rep. 10.1038/srep18627 (2016).
- Reproducibility
Improving the quality of publicly archived data
- Andrew M. Sugden
The deposition of research data in public archives and repositories is becoming common practice across the sciences, with many journals mandating the archiving of data associated with papers. However, in a survey of 100 publicly archived ecological and evolutionary data sets associated with recently published papers, Roche et al. found that fewer than 50% were complete and reusable. Many lacked necessary metadata, consisted of processed rather than raw data, or were presented in non-machine-readable formats, all of which are obstacles to reusing published analyses. The situation might be improved through the adoption of a reward culture, in which carrots rather than sticks for the public deposition of fully reusable data become the order of the day.
PLOS Biol. 10.1371/journal.pbio.1002295 (2015).
- Cancer Biology
The benefits of sloughing off
- Paula A. Kiberstis
Polymorphic neutrophils inhibit tumor cell growth in the mouse uterus
PHOTO: BLAISDELL ET AL., CANCER CELL (14 DECEMBER 2015) © CELL PRESS
The clinical success of cancer immunotherapy has intensified interest in the role of the various immune cells that infiltrate solid tumors. Among these are polymorphonuclear neutrophils (PMNs), potent effectors of inflammation that are thought to promote tumor growth. Blaisdell et al. studied mouse models of uterine cancer and found that, in contrast to expectation, PMNs inhibited tumor growth and progression, and that it was the hypoxic state of the tumors that attracted them. Once there, these immune cells caused the tumor cells to slough off from the uterine lining, resulting in their death. Human tumors with high levels of PMNs, as assessed by gene expression analyses, correlated with improved patient survival.
Cancer Cell 28, 785 (2015).
- Aging
Regulating progenitor competence over time
- Beverly A. Purnell
Because stem and progenitor cells serve in development and repair, their integrity is crucial for maintaining tissue function throughout an organism's life. However, many cellular mechanisms break down with time, and stem cells are probably not immune to this process. Farnsworth et al. explore the Notch signaling pathway as involved in cell fate determination for specific Drosophila neuroprogenitors termed intermediate neural progenitors (INPs). Young INPs respond just fine to Notch signaling, but old INPs lose this ability because of the presence of the inhibiting transcription factor Eyeless/Pax6, which interferes with Notch regulation of its target genes. Identifying the mechanisms and effects of aging will assist in understanding development, injury, and disease as they change over time.
Curr. Biol. 25, 3058 (2015).
- Nanotechnology
Artificial ion channels
- Julia Fahrenkamp-Uppenbrink
Structual model of a biomimetic, DNA-based ion channel
PHOTO: BURNS ET AL., NATURE NANOTECHNOLOGY (14 DECEMBER 2015) NATURE
Membrane proteins that form channels for ions to pass through are key regulators of transport into and out of biological cells. Burns et al. report a synthetic channel that can transport molecular ions across a bilayer in a controlled way. In contrast to biological ion channels, the synthetic channel is made from DNA, which folds into predictable structures and is easier to control than are proteins. The channel is held in the membrane via hydrophobic anchors. In the presence of a specific DNA “key,” it selectively transports small organic molecules with a positive charge across the bilayer. DNA channels of this kind are comparatively cheap and fast to produce and may find uses in drug delivery and synthetic biology.
Nat. Nanotechnol. 10.1038/NNANO.2015.279 (2015).
- Surface Assembly
Patterning colloids with microbubbles
- Phil Szuromi
A laser-based method can create arbitrary patterns of nanoparticles and colloids on plasmonic substrates with photothermally generated microbubbles. Lin et al. generated microbubbles in colloidal suspensions at low laser powers, using a plasmonic surface (a quasi-continuous gold nano-island film) that had its resonance tuned to the laser wavelength of 532 nm. The microbubbles captured and immobilized particles through Marangoni convection around the bubble, surface tension, gas pressure, and substrate adhesion. They patterned polystyrene nanoparticles (∼60 nm) and beads (∼0.5 to 5 µm) as well as 6-nm cadmium selenide-zinc sulfide core-shell nanoparticles.
Nano Lett. 5, 10.1021/acs.nanolett.5b04524 (2015).
- Planetary Science
Bright spots on Ceres may contain water
- Keith T. Smith
When NASA's Dawn spacecraft reached the dwarf planet Ceres in March 2015, there arose an immediate puzzle: What are the bright white spots located inside several surface craters? Natheus et al. have analyzed data from Dawn's camera and conclude that the most likely candidate is deposits of hydrated magnesium sulphate (Epsom salt): a compound that contains water. One crater called Occator fills with a haze each day, which disappears at night, probably caused by clouds of evaporated water. Deposits of salt and water ice just below the surface could be uncovered by impacts and provide clues to how Ceres was formed.
Nature 528, 237 (2015).
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