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A bioenergetic consumer–resource model is used to explore how and why only particular predator–prey body-mass ratios promote stability in tri-trophic food chains, and finds that this 'persistence domain' of ratios is constrained by bottom-up energy availability when predators are much smaller than their prey, and by enrichment-driven dynamics when predators are much larger.
A tiny disc-like structure on a silicon chip is simply illuminated by a conventional laser diode, and the resulting interaction between the laser light and the resonator gives rise to an optical frequency comb that emits in the infrared. The simplicity of the scheme, and the reduction in size, cost and power, should enhance the utility of optical frequency combs in a broad number of fields.
Autophagy contributes to host defence against infection. Toll like-receptor signals induce the recruitment of components of the autophagy pathway to phagosomes and facilitate phagosome lysosome fusion, resulting in killing of the invading organism.
This paper reports an NMR approach that enables the three-dimensional movement of two linked RNA helices to be followed for a period up to milliseconds. The two helices move in a highly correlated manner, demonstrating both twisting and bending. Results with different liganded conformations demonstrate that the motions of the unstructured RNA maps out positions within the dynamic envelope described by the bound structures.
This paper shows how noisy gene expression causes a bacterial cell to slowly lose track of time, as measured by its circadian clock. The theoretical framework thus introduced breaks the ground for the analysis of noise in other out-of-equilibrium living systems.
Exceptionally high resolution records of environmental change across the Palaeocene/Eocene boundary from two sediment sections in New Jersey find that the onset of environmental change and surface–ocean warming preceded the input of greenhouse gases by several thousand years. This sequence is consistent with the proposal that warming of the deep ocean caused the dissociation of submarine gas hydrates, which released massive amounts of methane.
This paper reports a study of polarons in a GaAs crystal subject to a strong electric field. In addition to the overall drift motion of the polaron, an oscillatory internal motion is observed in which the electron is impulsively moved away from the centre of the surrounding lattice distortion. Such quantum coherent processes directly affect high-frequency transport in nanostructures.
The first intracellular recordings from presynaptic boutons in the intact mammalian brain are presented. These results contradict the prevailing views (derived from in vitro work) on how the cerebellum integrates sensory information to control movement, by revealing a hitherto unexpected sensitivity of single brain connections to stimuli from the environment.
Use of neuronal imaging and photoactivation techniques on hippocampal pyramidal dendrites has shown that after long-term potentiation induction at individual synapses, neighbouring synapses become more easily potentiated, and across a broader time window. These results offer a new scale of information integration available for those modelling the cellular processes underlying brain function.
The crystal structure of the part of yeast topoisomerase II that binds DNA and catalyses breakage formation in complex with a gate DNA is solved. The enzyme sharply bends the DNA, which brings the DNA near the catalytic site and breaks a dimer interface of the protein, thereby opening a protein gate.
The transcription factor Nanog is considered a hallmark of pluripotent cells in vivo and in vitro, and loss of Nanog an early marker of differentiation. This is now revised by the demonstration that Nanog is not essential for maintaining pluripotency, but acts in stabilizing the pluripotent state.
A microfluidic platform that is capable of efficiently and selectively separating viable circulating tumour cells (CTCs) from peripheral blood samples has been developed. Low levels of CTCs in the peripheral blood of patients with various cancers were identified, and it was shown that this device could be used to monitor an individual patient's response to anti-cancer therapy.
The discovery of many fossil plants and clues from molecular genetics is starting to shed light on the relationship between angiosperms and other plants, and the sequence in which the unique features of angiosperms evolved.
Indonesia has been hit by more human deaths from the H5N1 bird-flu virus than any other country, yet it refuses to share its virus samples with the World Health Organization (WHO). Declan Butler talks to Indonesia's health minister.
