Flies are attracted to glycerol, a chemical in beer produced during fermentation. Understanding more about the genes responsible for taste and smell in flies could help make powerful insect repellents. iStockphoto.com hide caption

itoggle caption iStockphoto.com

H5N1 avian flu viruses (seen in gold) grow inside canine kidney cells (seen in green). Cynthia Goldsmith/CDC hide caption

itoggle caption Cynthia Goldsmith/CDC

The most common cause of brain injury in premature infants is a lack of oxygen in the days and weeks after birth, researchers say. Ibrahim Usta/AP hide caption

itoggle caption Ibrahim Usta/AP