Pest in peace Commercial ultrasonic frequency devices that claim to repel pests such as bed bugs through sound have shown to be ineffective. A new study in the Journal of Economic Entomology tested four such devices, all purchased online and used according to manufacturers' instructions. For each device, the authors created a sound arena and a control arena (with no sound). They found no significant differences in the number of bed bugs observed in the two arenas, and that bed bugs were neither deterred nor attracted to the arena with the sound device. The authors concluded the devices may not have produced the right frequencies.
Fins aren't what they used to beDarwinists, rejoice: Spanish researchers have found a scientific explanation of how fins may have evolved into legs. According to the study in the journal Developmental Cell, the development of hands and feet occurred through the gain of new DNA elements that activate particular genes. The scientists introduced extra Hoxd13, a gene known to play a role in distinguishing body parts, at the tip of a zebrafish embryo's fin. This led to the generation of new cartilage tissue that resembles key aspects of land-animal limb development. Also, a DNA control element that activates Hoxd13 in mouse embryonic limbs could cause the gene in the fin to produce something, too.
Fatten down Scientists at the Joslin Diabetes Centre in Boston have shown that brown fat transplants could help combat obesity. This type of fat is different from the white fat that's associated with increased body mass. Brown fat, a specialised tissue in mammals that's used to generate heat, is linked with a lower body mass index and consumes large amounts of energy. The researchers performed brown fat transplants in mice fed either a normal or high-fat diet, and found this significantly decreased body weight and improved insulin sensitivity and glucose metabolism. The transplanted fat also secreted hormones which affected the metabolism in the body.
Less food for thought
A new study published in Neurology suggests people who sometimes went hungry as children have slower cognitive decline in their elderly years compared with those who've always had enough food to eat. The study involved more than 6,000 Chicago residents with an average age of 75 tracked for up to 16 years. The link, however, was found only in African Americans; no similar relationship was found in white people. Study author Lisa Barnes, a neuropsychologist at Rush University Medical Centre in Chicago, theorises that calorie restriction can delay the onset of age-related changes in the body and increase the lifespan.