News & Views
According to previous studies, a low-calorie diet provides health benefits and increases lifespan in mammals, including primates. Yet a long-term investigation in rhesus monkeys finds no effect on longevity. See Letter
Past research implied that positive feedback might exist between climate change and greenhouse-gas emissions from soil. A study finds that drought-induced declines in such emissions from tropical forests could counter climate change.
A Facebook message sent out during the 2010 US congressional elections influenced the voting behaviour of millions of people. The experiment illustrates the power of digital social networks to spread behavioural change. See Letter
Biochemicals known as prostaglandins are challenging targets for synthetic organic chemistry. Yet by channelling the reactivity of a simple reactant, a powerful synthesis of one such compound has been achieved. See Letter
It has been unclear whether a uniform group of stem cells gives rise to most cells in the epidermis. A study reveals the presence of at least two stem-cell populations that have different proliferative abilities. See Article
An investigation of naturally occurring water recycling in rainforests finally marries the results of global climate models with observations. Alarmingly, it also suggests that deforestation can greatly reduce tropical rainfall. See Letter
The skin interfollicular epidermis (IFE) is the first barrier against the external environment and its maintenance is critical for survival. Two seemingly opposite theories have been proposed to explain IFE homeostasis. One posits that IFE is maintained by long-lived slow-cycling stem cells that give rise to transit-amplifying cell progeny, whereas the other suggests that homeostasis is achieved by a single committed progenitor population that balances stochastic fate. Here we probe the cellular heterogeneity within the IFE using two different inducible Cre recombinase–oestrogen receptor constructs targeting IFE progenitors in mice. Quantitative analysis of clonal fate data and proliferation dynamics demonstrate the existence of two distinct proliferative cell compartments arranged in a hierarchy involving slow-cycling stem cells and committed progenitor cells. After wounding, only stem cells contribute substantially to the repair and long-term regeneration of the tissue, whereas committed progenitor cells make a limited contribution.
Organisms that protect their germ-cell lineages from damage often do so at considerable cost: limited metabolic resources become partitioned away from maintenance of the soma, leaving the ageing somatic tissues to navigate survival amid an environment containing damaged and poorly functioning proteins. Historically, experimental paradigms that limit reproductive investment result in lifespan extension. We proposed that germline-deficient animals might exhibit heightened protection from proteotoxic stressors in somatic tissues. We find that the forced re-investment of resources from the germ line to the soma in Caenorhabditis elegans results in elevated somatic proteasome activity, clearance of damaged proteins and increased longevity. This activity is associated with increased expression of rpn-6, a subunit of the 19S proteasome, by the FOXO transcription factor DAF-16. Ectopic expression of rpn-6 is sufficient to confer proteotoxic stress resistance and extend lifespan, indicating that rpn-6 is a candidate to correct deficiencies in age-related protein homeostasis disorders.
Human ES-cell-derived cardiomyocytes electrically couple and suppress arrhythmias in injured hearts p.322