Editor's Choice: Megafauna, smoking, burning fat, bumble bees and cheese
A round-up of discoveries from the scientific and technical journals.
The paleo diet of the megafauna
The megafauna that roamed the Arctic during the Pleistocene were huge animals, as their name suggests. The woolly rhino, for example, weighed more than 3,000 kg and the woolly mammoth up to 6,000 kg. Until now, they were thought to have survived on a diet of grasses, based on the abundance of fossilised grass pollen found in soils of that time. But grass species produce more pollen than other types of plants, which seems to have skewed the picture. Now, after the first study of plant DNA preserved in the permafrost, scientists have discovered the area was dominated by protein-rich herbaceous plants called forbs, a much richer diet for a big beast. The forbs appear to have died out about 10,000 years ago – about the same time as many megafauna. Nature reports the study here.
Cold weather helps you burn fat
Winter could be the best time to kick-start a diet, with new research suggesting that 10 to 15 minutes of shivering is equivalent to about an hour of moderate exercise when it comes to converting energy-storing "white fat" into energy-burning "brown fat". Endocrinologist Paul Lee, from Sydney's Garvan Institute of Medical Research, recently undertook the study at the National Institutes of Health (NIH) in Washington DC. He discovered that to protect against the cold, fat and muscle communicate with each other using specific hormones to turn white fat cells into brown fat cells. Either exposure to the cold or exercise increase the levels of these hormones. The report of the study is here.
Even third hand smoke is bad for you
New evidence has emerged that suggests that tobacco smoke may be even more toxic, and for longer, than we thought. Tobacco fumes are classified into three categories: first-hand smoke, inhaled by the smoker, second-hand smoke that billows from a cigarette or is exhaled by the smoker and so-called "third-hand smoke", the second-hand smoke that condenses on surfaces. This appears to become progressively more toxic over time. Manuela Martins-Green, a professor of cell biology who led the study at University of California Riverside tested this material on mice. "We found significant damage occurs in the liver and lung. Wounds in these mice took longer to heal," she said. A report of the findings can be found here.
The bumble bee's unexpected aerodynamic power
The bumble bee's name does not suggest an animal capable of extreme flight performance at high altitudes. But a new study that reproduced oxygen-poor conditions and thin air similar to an altitude of 9,000 m – the equivalent of flying over Mount Everest – suggest the insects have plenty of wing power in reserve. The research, published by the Royal Society in the UK, showed the Alpine Bumble Bee can easily hover at high altitudes and changes the size of its stroke – not wingbeat frequency – to compensate for the thinner air. The researchers suggest bumble bees may, from time to time, need to show extreme performance way beyond that required for foraging for pollen. The report is here.
Natural DNA transfer found in cheese fungi
One concern about GM food often raised by its detractors is that DNA transfer between species seems “unnatural”. Not so. It’s been demonstrated between fungi and insects; microbes and plants. Now it turns out different species of cheese fungi do it too. After reading the genomes of the Penicillin species used to make cheeses such as Camembert and Roquefort, and comparing them to the one that makes medicinal penicillin, they turn out to share a big chunk of DNA called Wallaby. Author Ken Cheeseman (really his name) and colleagues say the only way it could have happened is if Wallaby “jumped” between species. His paper, published by Nature, is here.