New and Exciting in PLoS ONE

There are 27 new papers appearing on PLoS ONE today. A quick scan of the titles makes me want to read the following more carefully:
Plasticity of the Intrinsic Period of the Human Circadian Timing System by Frank A. J. L. Scheer, Kenneth P. Wright, Richard E. Kronauer and Charles A. Czeisler:

Human expeditions to Mars will require adaptation to the 24.65-h Martian solar day-night cycle (sol), which is outside the range of entrainment of the human circadian pacemaker under lighting intensities to which astronauts are typically exposed. Failure to entrain the circadian time-keeping system to the desired rest-activity cycle disturbs sleep and impairs cognitive function. Furthermore, differences between the intrinsic circadian period and Earth’s 24-h light-dark cycle underlie human circadian rhythm sleep disorders, such as advanced sleep phase disorder and non-24-hour sleep-wake disorders. Therefore, first, we tested whether exposure to a model-based lighting regimen would entrain the human circadian pacemaker at a normal phase angle to the 24.65-h Martian sol and to the 23.5-h day length often required of astronauts during short duration space exploration. Second, we tested here whether such prior entrainment to non-24-h light-dark cycles would lead to subsequent modification of the intrinsic period of the human circadian timing system. Here we show that exposure to moderately bright light (~450 lux; ~1.2 W/m2) for the second or first half of the scheduled wake episode is effective for entraining individuals to the 24.65-h Martian sol and a 23.5-h day length, respectively. Estimations of the circadian periods of plasma melatonin, plasma cortisol, and core body temperature rhythms collected under forced desynchrony protocols revealed that the intrinsic circadian period of the human circadian pacemaker was significantly longer following entrainment to the Martian sol as compared to following entrainment to the 23.5-h day. The latter finding of after-effects of entrainment reveals for the first time plasticity of the period of the human circadian timing system. Both findings have important implications for the treatment of circadian rhythm sleep disorders and human space exploration.

Acoel Flatworms Are Not Platyhelminthes: Evidence from Phylogenomics by Herve Philippe, Henner Brinkmann, Pedro Martinez, Marta Riutort and Jaume Baguna:

Acoel flatworms are small marine worms traditionally considered to belong to the phylum Platyhelminthes. However, molecular phylogenetic analyses suggest that acoels are not members of Platyhelminthes, but are rather extant members of the earliest diverging Bilateria. This result has been called into question, under suspicions of a long branch attraction (LBA) artefact. Here we re-examine this problem through a phylogenomic approach using 68 different protein-coding genes from the acoel Convoluta pulchra and 51 metazoan species belonging to 15 different phyla. We employ a mixture model, named CAT, previously found to overcome LBA artefacts where classical models fail. Our results unequivocally show that acoels are not part of the classically defined Platyhelminthes, making the latter polyphyletic. Moreover, they indicate a deuterostome affinity for acoels, potentially as a sister group to all deuterostomes, to Xenoturbellida, to Ambulacraria, or even to chordates. However, the weak support found for most deuterostome nodes, together with the very fast evolutionary rate of the acoel Convoluta pulchra, call for more data from slowly evolving acoels (or from its sister-group, the Nemertodermatida) to solve this challenging phylogenetic problem.

Regional Decline of Coral Cover in the Indo-Pacific: Timing, Extent, and Subregional Comparisons by John F. Bruno and Elizabeth R. Selig:

The Indo-Pacific region contains 75% of the world’s coral reefs, but little is known about ongoing changes to the level of coral cover across this region. Bruno and Selig find that levels of coral cover in the Indo-Pacific are currently much lower than expected, and that the rate of coral loss is between 1% and 2% per year.

Biometric Evidence that Sexual Selection Has Shaped the Hominin Face by Eleanor M. Weston, Adrian E. Friday and Pietro Lio:

Men and women tend to have differently shaped faces. Weston and colleagues show that these differences cannot simply be explained in terms of overall body size differences, and that some of them seem to be related to a rotation during development of the upper jaw. Some of these features may have emerged during evolution through selection for facial attractiveness.

…and many, many more. So, as always, go, read, annotate, rate and comment.

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