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- Chomez, A., et al.
(author)
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An imaged 15 MJup companion within a hierarchical quadruple system
- 2023
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 676, s. L10-L10
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Journal article (peer-reviewed)abstract
- Context. Since 2019, the direct imaging B-star Exoplanet Abundance STudy (BEAST) at SPHERE@VLT has been scanning the surroundings of young B-type stars in order to ascertain the ultimate frontiers of giant planet formation. Recently, the 17+3-4 Myr HIP 81208 was found to host a close-in (∼50 au) brown dwarf and a wider (∼230 au) late M star around the central 2.6 M⊙ primary.Aims. Alongside the continuation of the survey, we are undertaking a complete reanalysis of archival data aimed at improving detection performances so as to uncover additional low-mass companions.Methods. We present here a new reduction of the observations of HIP 81208 using the patch covariance algorithm (PACO), a recent and powerful algorithm dedicated to processing high-contrast imaging datasets, as well as more classical algorithms and a dedicated point spread function subtraction approach. The combination of different techniques allowed for a reliable extraction of astrometric and photometric parameters.Results. A previously undetected source was recovered at a short separation from the C component of the system. Proper motion analysis provided robust evidence for the gravitational bond of the object to HIP 81208 C. Orbiting C at a distance of ∼20 au, this 15 MJup brown dwarf becomes the fourth object of the hierarchical HIP 81208 system.Conclusions. Among the several BEAST stars which are being found to host substellar companions, HIP 81208 stands out as a particularly striking system. As the first stellar binary system with substellar companions around each component ever found by direct imaging, it yields exquisite opportunities for thorough formation and dynamical follow-up studies.
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- Pircher, P, et al.
(author)
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Aberrant expression of myosin isoforms in skeletal muscles from mice lacking the rev-erbAalpha orphan receptor gene
- 2005
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In: American journal of physiology. Regulatory, integrative and comparative physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 288:2, s. R482-R490
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Journal article (peer-reviewed)abstract
- The rev-erbAα orphan protein belongs to the steroid nuclear receptor superfamily. No ligand has been identified for this protein, and little is known of its function in development or physiology. In this study, we focus on 1) the distribution of the rev-erbAα protein in adult fast- and slow-twitch skeletal muscles and muscle fibers and 2) how the rev-erbAα protein influences myosin heavy chain (MyHC) isoform expression in mice heterozygous (+/−) and homozygous (−/−) for a rev-erbAα protein null allele. In the fast-twitch extensor digitorum longus muscle, rev-erbAα protein expression was linked to muscle fiber type; however, MyHC isoform expression did not differ between wild-type, +/−, or −/− mice. In the slow-twitch soleus muscle, the link between rev-erbAα protein and MyHC isoform expression was more complex than in the extensor digitorum longus. Here, a significantly higher relative amount of the β/slow (type I) MyHC isoform was observed in both rev-erbAα −/− and +/− mice vs. that shown in wild-type controls. A role for the ratio of thyroid hormone receptor proteins α1to α2in modulating MyHC isoform expression can be ruled out because no differences were seen in MyHC isoform expression between thyroid hormone receptor α2-deficient mice (heterozygous and homozygous) and wild-type mice. Therefore, our data are compatible with the rev-erbAα protein playing an important role in the regulation of skeletal muscle MyHC isoform expression.
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| 10. |
- Chomez, P, et al.
(author)
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Increased cell death and delayed development in the cerebellum of mice lacking the rev-erbA(alpha) orphan receptor
- 2000
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In: Development (Cambridge, England). - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 127:7, s. 1489-1498
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Journal article (peer-reviewed)abstract
- The rev-erbAα gene, belonging to the steroid receptor superfamily of transcription factors, is highly conserved during evolution but little is known so far about its functions in development or in adult physiology. Here, we describe genetically altered mice lacking the rev-erbAα gene. These animals do not show any obvious phenotype in either fat tissue or skeletal muscle, despite the known regulation of rev-erbAα expression during adipocyte and myotube differentiation in vitro. However, during the second week of life, the cerebellum of rev-erbAα mutants presents several unexpected abnormalities, such as alterations in the development of Purkinje cells, delay in the proliferation and migration of granule cells from the external granule cell layer and increased apoptosis of neurons in the internal granule cell layer. Interestingly, the expression pattern of rev-erbAα suggests that the abnormalities observed in the external granule cell layer could be secondary to Purkinje cell alterations. Taken together, our data underline the importance of rev-erbAα expression for the appropriate balance of transcriptional activators and repressors during postnatal cerebellar development.
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