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14 | NewScientist | 2 February 2013 IF TWO animals have identical brain cells, how different can they really be? Extremely. Two worm species have exactly the same set of neurons, but extensive rewiring allows them to lead completely different lives. Ralf Sommer of the Max Planck Institute for Developmental Biology in Tübingen, Germany, and colleagues compared Caenorhabditis elegans, which eats bacteria, with Pristionchus pacificus, which hunts other worms. Both have a cluster of 20 neurons to control their foregut. Sommer found that the clusters were identical. “These species are separated by 200 to 300 million years, but have the same cells,” he says. P. pacificus, however, has denser connections than C. elegans, with neural signals passing through many more cells Shrink the prostate without tears RELIEF from the constant call of nature is the aim of a new drug, tested in rats, which can shrink an enlarged prostate and is likely to have few side effects. By the age of 60 an estimated 70 per cent of men have prostate enlargement. Treatment involves surgery or drugs that block testosterone, a hormone that drives unwanted growth. Side effects can include loss of libido and erectile dysfunction. The new drug, RC-3940-II, developed by Andrew Schally of the Miami Veterans Affairs Medical Center in Florida and colleagues works by blocking gastrin-releasing peptide – another potent growth factor. In rats, a six-week treatment shrank prostates by 18 per cent. It also shrank human prostate cells by 21 per cent. Importantly, fewer side effects are likely as testosterone pathways are avoided (PNAS, DOI: 10.1073/pnas.1222355110). I’m supercool and control my own body clock NOT content with being the world’s coolest mammal, the Arctic ground squirrel now has another accolade: it is the first mammal known to switch its body clock on and off. The constant light of the Arctic summer and constant darkness of the winter make it difficult to tune circadian clocks to environmental cues. As a result, many Arctic species, such as reindeer, lack circadian rhythms entirely. Brian Barnes of the University of Alaska in Fairbanks and his colleagues wanted to test whether this was the case for the Arctic ground squirrel – famous for its ability to lower its body temperature to -3 ˚C during hibernation DARRELL GULIN/CORBIS IN BRIEF Identical brains, but one eats the other before reaching the muscles (Cell, doi.org/kbh). This suggests that P. pacificus is performing more complex motor functions, says Detlev Arendt of the European Molecular Biology Laboratory in Heidelberg, Germany. Arendt thinks predators were the first animals to evolve complex brains, to find and catch moving prey. He suggests their brains had flexible wiring, enabling them to swap from plant-eating to hunting. by supercooling its blood. So they put light-sensitive collars on squirrels to determine when the animals were in their burrows and when they were out. In their burrows during the winter, the animals’ body temperatures – detected by implanted transmitters – remained constant, indicating that their clocks were off. But once a squirrel emerged in spring, its body temperature rose during the day and fell at night. In the summer, the squirrels seemed to create their own sunrise and sunset by popping out of their burrows every day and retreating at “night”. This somehow tricked their body clocks into responding. Barnes thinks they could be using timing cues such as the position of the sun. The work was shown at the Society for Integrative and Comparative Biology meeting in San Francisco last month. A SCANDAL at the heart of the atom remains. The most precise reading yet of the proton’s radius confirms that it can seem smaller than quantum theory demands. The radius cannot be measured directly but can be inferred. In 2010, a group led by Randolf Pohl at the Max Planck Institute of Quantum Optics in Garching, Germany, used an exotic atom – a hydrogen with its electron replaced by the heavier muon – to put the proton’s radius at 0.8418 femtometres. That is 4 per cent smaller than when using ordinary hydrogen, a discrepancy quantum physics cannot explain. Now Pohl’s team has repeated the exotic measurement more precisely – and the mismatch is still there (Science, doi.org/kbp). Proton puzzle proves persistent
