The ability to perceive Earth's magnetic field, which at one time was dismissed as a physical impossibility, is now known to exist in diverse animals. The receptors for the magnetic sense remain elusive. But it seems that at least two underlying mechanisms exist — sometimes in the same organism

In the pancreas, insulin-producing ?-cells are long-lived and generally replicate seldom. They can do so, however, after increased metabolic demand or after injury. Here, a new transgenic model is developed in which ?-cells are nearly completely ablated in mice. If given insulin, these mice survive, and grow new ?-cells. Lineage-tracing shows that these new ?-cells come from ?-cells, revealing a previously disregarded degree of pancreatic cell plasticity

Here, the atmosphere of the extrasolar planet GJ 436b is studied during its 'secondary eclipse'. The findings reveal the presence of some H2O and traces of CO2. The best-fit compositional models contain a high CO abundance and a substantial methane deficiency relative to thermochemical equilibrium models for the predicted hydrogen-dominated atmosphere. Disequilibrium processes such as vertical mixing and polymerization of methane may be required to explain this small methane-to-CO ratio