Letters in 2014

Relatedness can affect fitness through modulation of intrasexual competition in Drosophila melanogaster; male competition and female harm are lower when three related males compete over an unrelated female than when three unrelated males compete, but when two brothers and an unrelated male compete, the unrelated male sires twice as many offspring as either brother, suggesting that minorities of unrelated competitors may be able to infiltrate coalitions of relatives.

Haematopoietic stem cells are found to be regulated differently in male and female mice — haematopoietic stem cells in females divide more frequently than in males in response to oestrogen and this difference depends on the ovaries but not the testes; using a genetic approach, it is shown that the effect is dependent on expression of oestrogen receptor-α (ERα) in stem cells.

A genetic locus from the gut symbiont Bacteroides ovatus is identified and described that encodes a cohort of enzymes and carbohydrate-binding proteins necessary for the metabolism of xyloglucans—a predominant component of dietary fibre.

A developmental regulator in Caulobacter evolved to specify the location of cell envelope morphogenesis in a related genus.

Tissue-resident macrophages are shown to stop lipopolysaccharide-induced inflammation by spreading an anti-inflammatory calcium signal to alveolar epithelial cells through connexin-43-positive gap junction channels.

Here, the helix–loop–helix transcription factor Ascl2 is shown to be critically important for the initiation of follicular T-helper-cell development and the germinal centre response.

Observations of a cosmic web filament have been made in Lyman-α emission; the filament has a projected size of approximately 460 physical kiloparsecs, and its estimated cold gas mass is more than ten times larger than what is typically found in cosmological simulations.

Rates of river incision into bedrock are thought to reflect rates of rock uplift as well as the strength of climatic forcing of erosion over time, but here incision rate is shown to depend on the measurement interval.

Sea-ice leads (open water channels), which increase with an ongoing shift from perennial to seasonal sea ice, are shown to initiate convection in the Arctic boundary layer, thus supplying ozone and gaseous mercury to the surface and possibly leading to additional pollution effects.

A mouse model shows that osteoblast activating β-catenin mutations alone are sufficient to initiate the development of acute myeloid leukaemia acting through increased Notch signalling.

Direct neural recordings from electrodes over bilateral cortices show that sensory–motor transformations for speech occur bilaterally; neural responses are robust during both perception and production in an overt word-repetition task, and bilateral sensory–motor responses can perform transformations between speech-perception and speech-production representations during a non-word transformation task.

Position and flap phasing between birds in formation flight indicate aerodynamic benefit.

A global analysis shows that for most tree species the largest trees are the fastest-growing trees, a finding that resolves conflicting assumptions about tree growth and that has implications for understanding forest carbon dynamics, resource allocation trade-offs within trees and plant senescence.

A black hole with mass 3.8 to 6.9 times that of the Sun is found to be orbiting the nearby Be-type star MWC 656; the black hole is encircled by an accretion disk and X-ray quiescent, implying that Be binaries with black-hole companions are difficult to detect in conventional X-ray surveys.

Generation of human induced pluripotent stem cells from patient fibroblasts containing ring chromosomes with large deletions reveals that reprogrammed cells lose the abnormal chromosome and duplicate the wild-type homologue through compensatory uniparental disomy, suggesting that cellular reprogramming may hold potential for ‘chromosome therapy’.

A study investigating the mechanisms underlying lateral inhibition and lineage plasticity in the mouse small intestine crypts in vivo finds that crypt cells maintain a permissive chromatin state upon which a transcription factor acts to determine lineage specification, and this is the basis of lateral inhibition.

Ecosystem mycorrhizal type is shown to have a stronger effect on soil carbon storage than temperature, precipitation, clay content and primary production; ecosystems dominated by ectomycorrhizal and ericoid mycorrhizal fungi contain 70% more soil carbon per unit nitrogen than do ecosystems dominated by arbuscular mycorrhizal fungi.

Flow batteries, in which the electro-active components are held in fluid form external to the battery itself, are attractive as a potential means for regulating the output of intermittent renewable sources of electricity; an aqueous flow battery based on inexpensive commodity chemicals is now reported that also has the virtue of enabling further improvement of battery performance through organic chemical design.

Dark melanin pigment was detected in the fossilized skin of three distantly related marine reptiles (a leatherback turtle, mosasaur and ichthyosaur); benefits of thermoregulation and/or crypsis may have contributed to this melanisation, which therefore has implications for our understanding of how these animals may have lived.

A new method for identifying genetic loci that influence protein expression in budding yeast reveals considerable complexity in how genetic variation shapes the proteome.