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Schödel R Ott T Genzel R Hofmann R Lehnert M Eckart A Mouawad N Alexander T Reid MJ Lenzen R Hartung M Lacombe F Rouan D Gendron E Rousset G Lagrange AM Brandner W Ageorges N Lidman C Moorwood AF Spyromilio J Hubin N Menten KM 《Nature》2002,419(6908):694-696
Many galaxies are thought to have supermassive black holes at their centres-more than a million times the mass of the Sun. Measurements of stellar velocities and the discovery of variable X-ray emission have provided strong evidence in favour of such a black hole at the centre of the Milky Way, but have hitherto been unable to rule out conclusively the presence of alternative concentrations of mass. Here we report ten years of high-resolution astrometric imaging that allows us to trace two-thirds of the orbit of the star currently closest to the compact radio source (and massive black-hole candidate) Sagittarius A*. The observations, which include both pericentre and apocentre passages, show that the star is on a bound, highly elliptical keplerian orbit around Sgr A*, with an orbital period of 15.2 years and a pericentre distance of only 17 light hours. The orbit with the best fit to the observations requires a central point mass of (3.7 +/- 1.5) x 10(6) solar masses (M(*)). The data no longer allow for a central mass composed of a dense cluster of dark stellar objects or a ball of massive, degenerate fermions. 相似文献
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Moorwood C 《Cellular and molecular life sciences : CMLS》2008,65(19):2957-2963
Syncoilin is a member of the intermediate filament protein family, highly expressed in skeletal and cardiac muscle. Syncoilin
binds α-dystrobrevin, a component of the dystrophin associated protein complex (DAPC) located at the muscle cell membrane,
and desmin, a muscle-specific intermediate filament protein, thus providing a link between the DAPC and the muscle intermediate
filament network. This link may be important for muscle integrity and force transduction during contraction, a theory that
is supported by the reduced force-generating capacity of muscles from syncoilin-null mice. Additionally, syncoilin is found
at increased levels in the regenerating muscle fibres of patients with muscular dystrophies and mouse models of muscle disease.
Therefore, syncoilin may be important for muscle regeneration in response to injury. The aims of this article are to review
current knowledge about syncoilin and to discuss its possible functions in skeletal muscle.
Received 21 May 2008; received after revision 10 July 2008; accepted 18 July 2008 相似文献
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Garfield AS Cowley M Smith FM Moorwood K Stewart-Cox JE Gilroy K Baker S Xia J Dalley JW Hurst LD Wilkinson LS Isles AR Ward A 《Nature》2011,469(7331):534-538
Imprinted genes, defined by their preferential expression of a single parental allele, represent a subset of the mammalian genome and often have key roles in embryonic development, but also postnatal functions including energy homeostasis and behaviour. When the two parental alleles are unequally represented within a social group (when there is sex bias in dispersal and/or variance in reproductive success), imprinted genes may evolve to modulate social behaviour, although so far no such instance is known. Predominantly expressed from the maternal allele during embryogenesis, Grb10 encodes an intracellular adaptor protein that can interact with several receptor tyrosine kinases and downstream signalling molecules. Here we demonstrate that within the brain Grb10 is expressed from the paternal allele from fetal life into adulthood and that ablation of this expression engenders increased social dominance specifically among other aspects of social behaviour, a finding supported by the observed increase in allogrooming by paternal Grb10-deficient animals. Grb10 is, therefore, the first example of an imprinted gene that regulates social behaviour. It is also currently alone in exhibiting imprinted expression from each of the parental alleles in a tissue-specific manner, as loss of the peripherally expressed maternal allele leads to significant fetal and placental overgrowth. Thus Grb10 is, so far, a unique imprinted gene, able to influence distinct physiological processes, fetal growth and adult behaviour, owing to actions of the two parental alleles in different tissues. 相似文献
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