The Evolution of Mammalian Gene Families

Gene families are groups of homologous genes that are likely to have highly similar functions. Differences in family size due to lineage-specific gene duplication and gene loss may provide clues to the evolutionary forces that have shaped mammalian genomes. Here we analyze the gene families contained within the whole genomes of human, chimpanzee, mouse, rat, and dog. In total we find that more than half of the 9,990 families present in the mammalian common ancestor have either expanded or contracted along at least one lineage. Additionally, we find that a large number of families are completely lost from one or more mammalian genomes, and a similar number of gene families have arisen subsequent to the mammalian common ancestor. Along the lineage leading to modern humans we infer the gain of 689 genes and the loss of 86 genes since the split from chimpanzees, including changes likely driven by adaptive natural selection. Our results imply that humans and chimpanzees differ by at least 6% (1,418 of 22,000 genes) in their complement of genes, which stands in stark contrast to the oft-cited 1.5% difference between orthologous nucleotide sequences. This genomic “revolving door” of gene gain and loss represents a large number of genetic differences separating humans from our closest relatives

The Many Faces of Red Giants

International audienc

The Many Faces of Red Giants

International audienc

The Many Faces of Red Giants

International audienc

Multiparametric MRI with dynamic contrast enhancement, diffusion-weighted imaging, and 31-phosphorus spectroscopy at 7 T for characterization of breast cancer

Objectives: To describe and to correlate tumor characteristics onmultiparametric 7 tesla (T) breast magnetic resonance imaging (MRI) with prognostic characteristics from postoperative histopathology in patients with breast cancer. Materials and Methods: Institutional review board approval and written informed consent of 15 women (46-70 years) with 17 malignant lesions were obtained. In this prospective study (March 2013 to March 2014), women were preoperatively scanned using dynamic contrast-enhanced MRI, diffusionweighted imaging, and 31-phosphorus spectroscopy (31P-MRS). The value of the protocol was assessed to quantify tumor differentiation and proliferation. Dynamic contrast-enhanced MRI was assessed according to the American College of Radiology Breast Imaging Reporting andData System-MRI lexicon.Apparent diffusion coefficients (ADCs) were calculated from diffusion-weighted imaging. On 31P-MRS, at the location of the tumor, the amount of phosphorus components was obtained in a localized spectrum. In this spectrum, the height of phosphodiester (PDE) and phosphomonoester (PME) peakswas assessed to serve as a measure for metabolic activity, stratifying tumors into a PDE > PME, PDE = PME, or PDE < PME group. Tumor grade andmitotic count fromresection specimenwere compared with the MRI characteristics using explorative analyses. Results: On dynamic contrast-enhanced MRI, the mean tumor size was 24 mm (range, 6-55 mm). An inverse trend was seen between ADC and tumor grade (P = 0.083), with mean ADC of 867 × 10-6 mm2/s for grade 1 (N = 4), 751 × 10-6 mm2/s for grade 2 (N = 6), and 659 × 10-6 mm2/s for grade 3 (N = 2) tumors. Between 31P-MR spectra andmitotic count, a relative increase of PME over PDE showed significant association with increasing mitotic counts (P = 0.02); a mean mitotic count of 6 was found in the PDE greater than PME group (N = 7), 8 in the PDE = PME group (N = 1), and 17 in the PDE < PME group (N = 3). Conclusions: Multiparametric 7 T breastMRI is feasible in clinical setting and shows association between ADC and tumor grade, and between 31P-MRS and mitotic count

The limb-darkened Arcturus: imaging with the IOTA/IONIC interferometer

Aims. We undertook an H band interferometric examination of Arcturus, a star frequently used as a spatial and spectral calibrator. Methods: Using the IOTA 3 telescope interferometer, we performed spectro-interferometric observations (R≈35) of Arcturus. Atmospheric models and prescriptions were fitted to the data to derive the brightness distribution of the photosphere. Image reconstruction was performed using two software algorithms: Wisard and Mira. Results: An achromatic power law proved to be a good model of the brightness distribution, with a limb darkening compatible with the one derived from atmospheric model simulations using our marcs model. A Rosseland diameter of 21.05±0.21 was derived, corresponding to an effective temperature of Teff = 4295±26 K. No companion was detected from the closure phases, with an upper limit on the brightness ratio of 8×10-4 at 1 AU. The dynamic range at such distance from the photosphere was established as 1.5×10-4 (1σ rms). An upper limit of 1.7×10-3 was also derived for the level of brightness asymmetries present in the photosphere.status: publishe