News & Views
Magnetic particles have been made that undergo synchronized oscillations when suspended in liquid in a rotating magnetic field. This discovery links the fields of nonlinear dynamics and materials science. See Letter p.578
The discovery of stone tools dating to 71,000 years ago at a site in South Africa suggests that the humans making them had developed the capacity for complex thought, and passed this knowledge down the generations. See Letter p.590
Spectroscopic analysis reveals that, at low temperatures, hydrophobic molecules dissolved in water strengthen the hydrogen bonding between nearby water molecules. But at high temperatures, the reverse can be true. See Letter p.582
Researchers have coaxed cultured embryonic stem cells to develop into eggs that then give rise to normal offspring. The discovery should help to decode the molecular basis of gamete formation and might lead to treatments for infertility.
Exposure to abnormal light–dark cycles causes depression-like behaviour and learning deficits in mice. The defects seem to occur independently of disturbances to sleep and other processes regulated by the biological clock. See Letter p.594
The identification of a sea-floor microorganism that single-handedly conducts anaerobic oxidation of methane changes our picture of how the flux of this greenhouse gas from the ocean to the atmosphere is regulated. See Article p.541
Cold and ultracold molecules provide fertile grounds for scientific discoveries. A method of cooling polyatomic molecules has been demonstrated that will allow researchers to explore the vast potential of these entities. See Letter p.570
Hippocampal ripples, episodic high-frequency field-potential oscillations primarily occurring during sleep and calmness, have been described in mice, rats, rabbits, monkeys and humans, and so far they have been associated with retention of previously acquired awake experience. Although hippocampal ripples have been studied in detail using neurophysiological methods, the global effects of ripples on the entire brain remain elusive, primarily owing to a lack of methodologies permitting concurrent hippocampal recordings and whole-brain activity mapping. By combining electrophysiological recordings in hippocampus with ripple-triggered functional magnetic resonance imaging, here we show that most of the cerebral cortex is selectively activated during the ripples, whereas most diencephalic, midbrain and brainstem regions are strongly and consistently inhibited. Analysis of regional temporal response patterns indicates that thalamic activity suppression precedes the hippocampal population burst, which itself is temporally bounded by massive activations of association and primary cortical areas. These findings suggest that during off-line memory consolidation, synergistic thalamocortical activity may be orchestrating a privileged interaction state between hippocampus and cortex by silencing the output of subcortical centres involved in sensory processing or potentially mediating procedural learning. Such a mechanism would cause minimal interference, enabling consolidation of hippocampus-dependent memory.
Regulatory T (Treg) cells, characterized by expression of the transcription factor forkhead box P3 (Foxp3), maintain immune homeostasis by suppressing self-destructive immune responses. Foxp3 operates as a late-acting differentiation factor controlling Treg cell homeostasis and function, whereas the early Treg-cell-lineage commitment is regulated by the Akt kinase and the forkhead box O (Foxo) family of transcription factors. However, whether Foxo proteins act beyond the Treg-cell-commitment stage to control Treg cell homeostasis and function remains largely unexplored. Here we show that Foxo1 is a pivotal regulator of Treg cell function. Treg cells express high amounts of Foxo1 and display reduced T-cell-receptor-induced Akt activation, Foxo1 phosphorylation and Foxo1 nuclear exclusion. Mice with Treg-cell-specific deletion of Foxo1 develop a fatal inflammatory disorder similar in severity to that seen in Foxp3-deficient mice, but without the loss of Treg cells. Genome-wide analysis of Foxo1 binding sites reveals ∼300 Foxo1-bound target genes, including the pro-inflammatory cytokine Ifng, that do not seem to be directly regulated by Foxp3. These findings show that the evolutionarily ancient Akt–Foxo1 signalling module controls a novel genetic program indispensable for Treg cell function.