The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics

Predicted miRNAs in murine dystrophin gene

Duchenne muscular dystrophy (DMD) is a common X-linked disease characterized by frameshift mutations in the dystrophin gene. Among the molecular mechanisms potentially involved in DMD, we focused our attention on microRNAs (miRNAs) a new class of gene-expression regulators. The identification of new predicted miRNAs in dystrophin gene could evidence a molecular network specific for DMD. To predict the presence of pre-miRNA in the dystrophin gene, we analyzed its genomic sequence with three microRNA-gene prediction algorithms (mirEval, mirFinder and MiR-abela) which analyze criteria such as the secondary structure and free-folding energy of their precursors, conservation of part of the miRNA sequence or similarity with other miRNAs and since miRNA are occasionally found in clusters, analysis of genomic regions around already known miRNA. A set of 28 pre-miRNAs were predicted to be encoded within the dystrophin gene. The various predictions were compared considering the localization and the structure of the predicted stem loops; 14 of them were resulted in common to all three algorithms. Sequences of predicted miRNA were checked in miRbase and aligned with known stem-loop precursors and mature miRNAs. This analysis evidenced that five putative pre-miRNA showed significant similarity with known miRNAs thus letting suppose that the dystrophin gene could contain new transcription sites for annotated miRNAs. The remaining 23 predictions did not show any alignment with already validated miRNAs and could represent new miRNA molecules. Validation of these predicted miRNAs within dystrophin gene will add new intrinsic molecular networks to the characterization of DMD pathogenesis and could explain the variability of the DMD clinical phenotypes. However, all these findings raise the opportunity for therapeutic intervention at the miRNA level preventing specific pathways underlying this muscle disease. This work has been supported by the Associazione Amici del Centro Dino Ferrari, the Association Monégasque contre les Myopathies, Optistem 223098 and the Associazione La Nostra Famiglia Fondo DMD Gli Amici di Emanuele. MiRNA-dysregulation in dystrophic single fiber

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

[[sponsorship]]生物化學研究所[[note]]已出版;[SCI];有審查制度;具代表性[[note]]http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Drexel&SrcApp=hagerty_opac&KeyRecord=1554-8627&DestApp=JCR&RQ=IF_CAT_BOXPLO