Identification of Mest/Peg1 gene expression as a predictive biomarker of adipose tissue expansion sensitive to dietary anti-obesity interventions

Food components with anti-obesity properties are commonly evaluated using mouse models of diet-induced obesity. The ability of these components to reduce or prevent white adipose tissue (WAT) accumulation is usually tested in feeding trials of several weeks duration in order to detect significant effects on fat mass expansion. Here, we aimed to identify early, predictive biomarkers for WAT expansion. We performed a 5-day high-fat diet (HFD) feeding trial with C57BL/6J mice using different established anti-obesity interventions: epigallocatechin gallate, replacing dietary lipids by n-3 PUFA, and increasing dietary protein. WAT gene expression was analyzed of genes known to be similarly affected by short- and long-term HFD. Gene expression of Leptin and Mest (mesoderm-specific transcript) was increased by HFD and normalized by all anti-obesity interventions. In a second experiment, translatability to whole blood-based expression data was assessed. Mice were challenged for 21 days with a HFD without or with simultaneous treatment with anti-obesity bioactives, hydroxytyrosol or resveratrol, and compared for parameters including Leptin and Mest expression in whole blood at day 5. While Leptin mRNA could not be detected in mouse whole blood, there was an induction of Mest mRNA by HFD which was suppressed by hydroxytyrosol. Moreover, Mest expression in whole blood at day 5 positively correlated with adiposity and negatively with lean body mass and the subcutaneous/visceral fat ratio at day 21. We conclude that gene expression of Leptin and Mest in WAT and of Mest in whole blood represent early, predictive markers of adipose tissue expansion of potential usefulness in nutritional studies and trials

The Polarimetric and Helioseismic Imager on Solar Orbiter

This paper describes the Polarimetric and Helioseismic Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and helioseismology instrument to observe the Sun from outside the Sun-Earth line. It is the key instrument meant to address the top-level science question: How does the solar dynamo work and drive connections between the Sun and the heliosphere? SO/PHI will also play an important role in answering the other top-level science questions of Solar Orbiter, while hosting the potential of a rich return in further science. Methods. SO/PHI measures the Zeeman effect and the Doppler shift in the Fe I 617.3 nm spectral line. To this end, the instrument carries out narrow-band imaging spectro-polarimetry using a tunable LiNbO3 Fabry-Perot etalon, while the polarisation modulation is done with liquid crystal variable retarders. The line and the nearby continuum are sampled at six wavelength points and the data are recorded by a 2k × 2k CMOS detector. To save valuable telemetry, the raw data are reduced on board, including being inverted under the assumption of a Milne-Eddington atmosphere, although simpler reduction methods are also available on board. SO/PHI is composed of two telescopes; one, the Full Disc Telescope, covers the full solar disc at all phases of the orbit, while the other, the High Resolution Telescope, can resolve structures as small as 200 km on the Sun at closest perihelion. The high heat load generated through proximity to the Sun is greatly reduced by the multilayer-coated entrance windows to the two telescopes that allow less than 4% of the total sunlight to enter the instrument, most of it in a narrow wavelength band around the chosen spectral line. Results. SO/PHI was designed and built by a consortium having partners in Germany, Spain, and France. The flight model was delivered to Airbus Defence and Space, Stevenage, and successfully integrated into the Solar Orbiter spacecraft. A number of innovations were introduced compared with earlier space-based spectropolarimeters, thus allowing SO/PHI to fit into the tight mass, volume, power and telemetry budgets provided by the Solar Orbiter spacecraft and to meet the (e.g. thermal) challenges posed by the mission's highly elliptical orbit