In Science this week, a team led by Stanford University's Carlos Bustamante report that an amino acid change causes blond hair in Solomon Islanders. Naturally blond hair is usually only found in Europe and Oceania, but in this study, the team identifies an arginine-to-cysteine change at a highly conserved residue in TYRP1 as a major determinant of the trait in people from the Solomon Islands. "This missense mutation is predicted to affect catalytic activity of TYRP1 and causes blond hair through a recessive mode of inheritance," the authors write. The mutation has a 26 percent frequency in the Islands and is absent outside of Oceania. "[It] represents a strong common genetic effect on a complex human phenotype, and highlights the importance of examining genetic associations worldwide," the team adds.
Also in Science this week, researchers in Spain report that imaginal discs in Drosophila mediate growth and maturation of the flies. These discs autonomously activate a Drosophila insulin-like peptide called DILP8, which regulates abnormal growth and postpones maturation. "DILP8 delays metamorphosis by inhibiting ecdysone biosynthesis, slowing growth in the imaginal discs, and generating normal-sized animals," the authors write. "Loss of DILP8 yields asymmetric individuals with an unusually large variation in size and a more varied time of maturation."
In Science Translational Medicine this week, researchers at the University of Maryland School of Medicine and the University of Idaho describe the temporal dynamics of the vaginal microbiome. The team studied the vaginal microbiomes of 32 reproductive-age women over a 16-week period and found five major classes of bacterial communities. Some communities changed "markedly" over a short period of time, while others remained stable, the team says. "Modeling community stability using new quantitative measures indicates that deviation from stability correlates with time in the menstrual cycle, bacterial community composition, and sexual activity," they add.
Also in Science Translational Medicine this week, researchers in Texas describe human mesenchymal stem cell-derived matrices developed to aid in osteoregeneration. Using a mouse model of calvarial healing, the team shows that the capacity of human mesenchymal stem cells to repair bone can be enhanced by treatment with an inhibitor of peroxisome proliferator–activated receptor γ, but the efficacy of this is limited. To get around this limitation, the team "prepared a scaffold consisting of hMSC-derived extracellular matrix containing the necessary biomolecules for extended site-specific hMSC retention."