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14 | NewScientist | 20 October 2012 NEVER underestimate the value of a good night’s sleep. Not only does a lack of shut-eye leave you irritable, it has been linked to diabetes and weight gain, though no one understood why. To investigate, Matthew Brady at the University of Chicago and his colleagues tested fat cells taken from the bellies of seven adults after four nights of sleeping up to 8 and a half hours, and then again after four nights on a measly 4 and a half hours. The team found that after sleep deprivation fat cells from the same person were on average 30 per cent less responsive to insulin – a hormone that makes muscle, liver and fat cells take up glucose after a meal (Annals of Internal Medicine, DOI: 10.7326/0003- 4819-157-8-201210160-00005). High blood glucose levels are Fruit flies’ eyes shrink a little to see I SPY, with my mechanical eye. It seems shrinking cells play a vital role in insect eyesight, and perhaps other sensory systems, too. The eyes of the common fruit fly (Drosophila melanogaster) contain rods of light-sensitive cells. When light strikes one of these cells, it causes a chemical cascade, opening channels in the cell’s membrane. This, in turn, sends a signal to the fly’s brain. But no one knew how these chemicals opened the channels. Roger Hardie of the University of Cambridge has now found that the chemicals break down the membrane’s molecules, reducing its surface area. When several cells shrink, the entire rod contracts by up to 400 nanometres (Science, doi.org/jhj). “It’s like a little muscle twitching,” he says. This contraction probably helps the channels to open, perhaps by deforming them. Other senses might use the same mechanism. Building blocks of Angkor Wat were shipped in by canal IT IS never too late to find a shortcut. Centuries after the construction of Cambodia’s Angkor Wat, archaeologists have uncovered traces of a series of canals that suggest the 5 million tonnes of sandstone used to build the temples took a far shorter route than previously thought. The sandstone blocks each weigh up to 1.5 tonnes and originate from quarries at Mount Kulen. It was thought they were taken 35 kilometres along a canal to Tonlé Sap Lake, rafted another 35 km along the lake, then taken up the Siem Reap River for 15 km, against the current. Thinking this was unlikely, Etsuo Uchida and Ichita RICHARD NOWITZ/NGS IN BRIEF Lack of sleep makes fat cells sluggish linked to diabetes. Fat cells also normally release the appetite- regulating hormone leptin. Brady suggests that if sleep-deprived cells are generally malfunctioning, this mechanism may also be disrupted, affecting weight gain. “We were surprised at how robust the response was,” says Brady. “Four nights of sleep curtailment represents a real- world situation, such as sitting for final exams or having a newborn in the house.” Shimoda of Waseda University in Tokyo, Japan, used satellite images to search for a shortcut. The canals they discovered led from the foot of Mount Kulen to Angkor – a gentle 34-km route, as opposed to the arduous 90-km trek previously suggested. The pair also uncovered more than 50 quarries at the foot of Mount Kulen and along the route. The stones they found matched those in the temples (Journal of Archaeological Science, doi.org/jhf). Uchida believes all the stone used for the monuments was probably transported along these canals. Mitch Hendrickson of the University of Illinois, Chicago, says Uchida’s theory could be confirmed by searching for blocks that fell overboard into the canals. He believes the canals were used for several purposes, including the transportation of important minerals such as iron. WHEN in Rome, you get a little hit of cocaine with every breath. A study of psychotropic drug levels in ambient air from eight Italian cities found background levels of cocaine, cannabinoids – the active ingredients in marijuana – nicotine and caffeine in every urban centre. Turin had the highest concentrations of cocaine, says Angelo Cecinato at the Institute of Atmospheric Pollution Research in Rome. Meanwhile, Bologna and Florence had some of the highest cannabinoid levels, which Cecinato attributes to the large student populations in the two cities. The drug concentrations are much too low to have an effect, though (Environmental Pollution, doi.org/jhk). Italian city air is nothing to snort at
