| 1. |
- Luque, R., et al.
(author)
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A resonant sextuplet of sub-Neptunes transiting the bright star HD 110067
- 2023
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In: Nature. - 0028-0836 .- 1476-4687. ; 623:7989, s. 932-937
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Journal article (peer-reviewed)abstract
- Planets with radii between that of the Earth and Neptune (hereafter referred to as ‘sub-Neptunes’) are found in close-in orbits around more than half of all Sun-like stars 1,2. However, their composition, formation and evolution remain poorly understood 3. The study of multiplanetary systems offers an opportunity to investigate the outcomes of planet formation and evolution while controlling for initial conditions and environment. Those in resonance (with their orbital periods related by a ratio of small integers) are particularly valuable because they imply a system architecture practically unchanged since its birth. Here we present the observations of six transiting planets around the bright nearby star HD 110067. We find that the planets follow a chain of resonant orbits. A dynamical study of the innermost planet triplet allowed the prediction and later confirmation of the orbits of the rest of the planets in the system. The six planets are found to be sub-Neptunes with radii ranging from 1.94R ⊕ to 2.85R ⊕. Three of the planets have measured masses, yielding low bulk densities that suggest the presence of large hydrogen-dominated atmospheres.
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| 2. |
- Leleu, A., et al.
(author)
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Six transiting planets and a chain of Laplace resonances in TOI-178
- 2021
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 649
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Journal article (peer-reviewed)abstract
- Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152 to 2.87 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02 to 0.177 times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes. -0.070 -0.13 -0.23 -0.061 +0.073 +0.14 +0.28 +0.055
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| 3. |
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| 4. |
- Kehoe, Laura, et al.
(author)
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Make EU trade with Brazil sustainable
- 2019
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Journal article (other academic/artistic)
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| 5. |
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| 6. |
- Moyano, A. L., et al.
(author)
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Sulfatides in Extracellular Vesicles Isolated From Plasma of Multiple Sclerosis Patients
- 2016
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In: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 94:12, s. 1579-1587
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Journal article (peer-reviewed)abstract
- Extracellular vesicles (EVs) are membrane nanovesicles of diverse sizes secreted by different cell types and are involved in intercellular communication. EVs shuttle proteins, nucleic acids, and lipids that reflect their cellular origin and could mediate their biological function in recipient cells. EVs circulate in biological fluids and are considered as potential biomarkers that could be used to analyze and characterize disease development, course and response to treatment. EVs exhibit specific distribution of glycolipids and membrane organization, but little is known about the biological significance of this distribution or how it could contribute to pathological conditions such as multiple sclerosis (MS). We provide the first description of sulfatide composition in plasma-derived EVs by ultra-high-performance liquid chromatography tandem mass spectrometry. We found that EVs of different sizes showed C16:0 sulfatide but no detectable levels of C18:0, C24:0, or C24:1 sulfatide species. Small EVs isolated at 100,000 x g-enriched in exosomes-from plasma of patients with MS showed a significant increase of C16: 0 sulfatide compared with healthy controls. Nanoparticle tracking analysis showed that the particle size distribution in MS plasma was significantly different compared with healthy controls. Characterization of small EVs isolated from MS plasma showed similar protein content and similar levels of exosomal markers (Alix, Rab-5B) and vesicular marker MHC class I (major histocompatibility complex class I) compared with healthy controls. Our findings indicate that C16: 0 sulfatide associated with small EVs is a candidate biomarker for MS that could potentially reflect pathological changes associated with this disease and/or the effects of its treatment.
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| 7. |
- Moyano, A. L., et al.
(author)
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Distribution of C16:0, C18:0, C24:1, and C24:0 sulfatides in central nervous system lipid rafts by quantitative ultra-high-pressure liquid chromatography tandem mass spectrometry
- 2014
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In: Analytical Biochemistry. - : Elsevier BV. - 0003-2697. ; 467, s. 31-39
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Journal article (peer-reviewed)abstract
- Sulfated galactosylceramides (sulfatides) are glycosphingolipids associated with cholesterol- and sphingolipid-enriched membrane microdomains (lipid rafts) and are highly expressed in brain tissue. Although it is known that sulfatide species show heterogeneity in their fatty acid acyl group composition throughout brain development, their lipid raft distribution and biological relevance is poorly understood. We validated a fast and sensitive ultra-high-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method to measure developmentally regulated sulfatide species (06:0, C18:0, C24:1, and C24:0) in central nervous system (CNS) lipid rafts isolated without using detergent. Our UHPLC-MS/MS assay showed good accuracy and precision with a linear range of 5 to 1000 nM for C18:0 and C24:1 sulfatides and 10 to 1000 nM for 06:0 and C24:0 sulfatides. We applied this quantitative analysis to detergent-free lipid rafts isolated from wild-type mice and arylsulfatase A-deficient (ASA knockout) mice that accumulate sulfatides. All four sulfatide species were more abundant in raft membranes than in non-raft membranes, with a significant increase in lipid rafts isolated from ASA knockout mice. This is the first description of an analytical method to study these sulfatide species in raft and non-raft membranes and has the potential to be applied to preparations from other tissues.
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| 8. |
- Moyano, A. L., et al.
(author)
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Levels of plasma sulfatides C18: 0 and C24: 1 correlate with disease status in relapsing-remitting multiple sclerosis
- 2013
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In: Journal of Neurochemistry. - : Wiley. - 0022-3042. ; 127:5, s. 600-604
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Journal article (peer-reviewed)abstract
- Multiple sclerosis (MS) is considered an autoimmune demyelinating disease of the CNS and myelin-derived glycolipids are one of the targets of this autoimmune attack. In this study, we examined for the first time the plasma distribution of sulfatide isoforms. Sulfatides with long-chain (C24:0 or C24:1) and short-chain (C16:0 or C18:0) fatty acids were quantified in plasma of relapsing-remitting MS patients by ultra-high-performance liquid chromatography tandem mass spectrometry. We found that C18:0 and C24:1 sulfatide plasma levels positively correlated with the Expanded Disability Status Scale. C16/C18:0 and C16/C24:0 ratios also correlated with the age and the time since last relapse. Healthy women showed higher levels of C16:0 sulfatide than healthy men; however, this gender difference disappeared in MS patients. Our data underline the potential use of sulfatides as biomarkers in relapsing-remitting MS and points to a possible association with the higher susceptibility of women to develop MS.
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| 9. |
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| 10. |
- Pituch, K. C., et al.
(author)
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Dysfunction of Platelet-derived Growth Factor Receptor a (PDGFR alpha) Represses the Production of Oligodendrocytes from Arylsulfatase A-deficient Multipotential Neural Precursor Cells
- 2015
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In: Journal of Biological Chemistry. - 0021-9258. ; 290:11, s. 7040-7053
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Journal article (peer-reviewed)abstract
- The membrane-bound receptor for platelet-derived growth factor A (PDGFR alpha) is crucial for controlling the production of oligodendrocytes (OLs) for myelination, but regulation of its activity during OL differentiation is largely unknown. We have examined the effect of increased sulfated content of galactosylceramides (sulfatides) on the regulation of PDGTR alpha in multipotential neural precursors (NPs) that are deficient in arylsulfatase A (ASA) activity. This enzyme is responsible for the lysosomal hydrolysis of sulfatides. We show that sulfatide accumulation significantly impacts the formation of OLs via deregulation of PDGFR alpha function. PDGFR alpha is less associated with detergent-resistant membranes in ASA-deficient cells and showed a significant decrease in AKT phosphorylation Rescue experiments with ASA showed a normalization of the ratio of long versus short sulfatides, restored PDGTRa levels, corrected its localization to detergent-resistant membranes, increased AKT phosphorylation, and normalized the production of OLs in ASA-deficient NPs. Moreover, our studies identified a novel mechanism that regulates the secretion of PDGFR alpha in NPs, in glial cells, and in the brain cortex via exosomal shedding. Our study provides a first step in understanding the role of sulfatides in regulating PDGFR alpha levels in OLs and its impact in myelination.
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