In Science this week, a team led by University of Tubingen researchers report the sequencing and analysis of the genomes of medieval and modern Mycobacterium leprae, the pathogen responsible for leprosy, using ancient skeletons and existing patients. They found that the bacterium has not changed much genetically over the past millennium, with only about 800 mutations occurring among the 16 genomes examined, and that strains from the Americas most likely originated in Europe.
Also in Science, Japanese investigators describe the discovery of two microRNAs that may play a key role in human reproduction. Ovulation in mammals is controlled by hormones secreted by the hypothalamopituitary-ovarian axis — the hypothalamus, pituitary gland, and gonads — which also expresses miRNAs. The scientists created knockout mice lacking miR-200b, which is detected in male reproductive organs, and ones lacking miR-429, which sits near the other miRNA in the mouse genome. While males were unaffected by the missing miRNAs, female mice experienced a sharp decrease in fertility. Because the miR-200b cluster is also present in people, the findings suggest that the miRNAs also be involved in human reproduction.