Less may be more for a successful smile
New research published in PLOS ONE suggests that a smile rated as effective, genuine and pleasant hits a smile “sweet spot.” The study authors asked 802 participants to rate varying expressions on a series of 3-D computer-animated facial models. They found that “successful” smiles achieve an optimal balance of teeth, mouth angle and smile extent, rather than following the “more is better” principle.
Since medical conditions such as stroke may hinder some peoples’ facial expressiveness, with possible psychological and social consequences, these results could also inform facial reanimation surgery and rehabilitation practices.
Copying useful genes helps yeast conquer new environments
A PLOS Biology study reveals a new mechanism in yeast that accelerates the copying of useful genes, allowing cells to adapt to environmental changes more rapidly. The researchers examined a gene that aids copper tolerance, CUP1, and found that in high-copper environments, variation in CUP1 copy number increased. As a result, some yeast cells gained additional copies of the CUP1 gene, and were therefore more copper-tolerant and better adapted to the environment, outcompeting other cells.
Further work by the authors demonstrated that a protein called Rtt109, which adds chemical modifications to particular sites in the genome, can aid this process and promote copy number change in useful areas. While such genetic change was generally thought to be a purely random process, this research may demonstrate how cells focus it to adapt to changing environments, and future work could examine the mechanism’s applicability to other genes.
Elephantiasis declining in Cameroon
Lymphatic filariasis — a parasitic infection commonly known as elephantiasis — is among the 10 neglected tropical diseases that the World Health Organization (WHO) aims to eliminate by 2020. New PLOS Neglected Tropical Diseases research suggests that large-scale annual mass drug administration efforts are successfully curbing the disease in Cameroon.
Researchers examined 5,292 young children from five health districts in Cameroon. The selected districts had conducted six annual mass drug campaigns and achieved drug coverage rates of at least 65 percent. The authors found that rates of lymphatic filariasis detected in blood samples were low, below WHO critical thresholds for stopping treatment. While the results are encouraging, the researchers caution against the cessation of mass drug administration before surveillance activities have evaluated the impact of such a move.
Image Credit: Helwig et al (2017)
Hull RM, Cruz C, Jack CV, Houseley J (2017) Environmental change drives accelerated adaptation through stimulated copy number variation. PLoS Biol 15(6): e2001333. https://doi.org/10.1371/journal.pbio.2001333
Nana-Djeunga HC, Tchouakui M, Njitchouang GR, Tchatchueng-Mbougua JB, Nwane P, Domche A, et al. (2017) First evidence of lymphatic filariasis transmission interruption in Cameroon: Progress towards elimination. PLoS Negl Trop Dis 11(6): e0005633. https://doi.org/10.1371/journal.pntd.0005633