40 research outputs found
The metamorphosis of SN1998bw
We present and discuss the photometric and spectroscopic evolution of the
peculiar SN1998bw, associated with GRB980425, through an analysis of optical
and near IR data collected at ESO-La Silla. The spectroscopic data, spanning
the period from day -9 to day +376 (relative to B maximum), have shown that
this SN was unprecedented, although somewhat similar to SN1997ef. Maximum
expansion velocities as high as 3x10^4 km/s to some extent mask its resemblance
to other Type Ic SNe. At intermediate phases, between photospheric and fully
nebular, the expansion velocities (~10^4 km/s) remained exceptionally high
compared to those of other recorded core-collapse SNe at a similar phase. The
mild linear polarization detected at early epochs suggests the presence of
asymmetry in the emitting material. The degree of asymmetry, however, cannot be
decoded from these measurements alone. The HeI 1.083 mu and 2.058 mu lines are
identified and He is suggested to lie in an outer region of the envelope. The
temporal behavior of the fluxes and profiles of emission lines of MgI]4571A,
[OI]6300,6364A and a feature ascribed to Fe are traced to stimulate future
modeling work.Comment: 32 pages, 19 figures; ps file including figures at
http://www.eso.org/~fpatat/sn98b
Mutations in sphingosine-1-phosphate lyase cause nephrosis with ichthyosis and adrenal insufficiency
Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in SGPL1, which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representing SGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficient dpl1. yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown of Sgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. In Drosophila, Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WT Sply, but not the disease-associated variants, rescued this phenotype. Together, these results indicate that SGPL1 mutations cause a syndromic form of SRNS
From Shock Breakout to Peak and Beyond: Extensive Panchromatic Observations of the Type Ib Supernova 2008D associated with Swift X-ray Transient 080109
We present extensive early photometric (ultraviolet through near-infrared)
and spectroscopic (optical and near-infrared) data on supernova (SN) 2008D as
well as X-ray data analysis on the associated Swift/X-ray transient (XRT)
080109. Our data span a time range of 5 hours before the detection of the X-ray
transient to 150 days after its detection, and detailed analysis allowed us to
derive constraints on the nature of the SN and its progenitor; throughout we
draw comparisons with results presented in the literature and find several key
aspects that differ. We show that the X-ray spectrum of XRT 080109 can be fit
equally well by an absorbed power law or a superposition of about equal parts
of both power law and blackbody. Our data first established that SN 2008D is a
spectroscopically normal SN Ib (i.e., showing conspicuous He lines), and show
that SN 2008D had a relatively long rise time of 18 days and a modest optical
peak luminosity. The early-time light curves of the SN are dominated by a
cooling stellar envelope (for \Delta t~0.1- 4 day, most pronounced in the blue
bands) followed by 56^Ni decay. We construct a reliable measurement of the
bolometric output for this stripped-envelope SN, and, combined with estimates
of E_K and M_ej from the literature, estimate the stellar radius R_star of its
probable Wolf-Rayet progenitor. According to the model of Waxman et al. and of
Chevalier & Fransson, we derive R_star^{W07}= 1.2+/-0.7 R_sun and
R_star^{CF08}= 12+/-7 R_sun, respectively; the latter being more in line with
typical WN stars. Spectra obtained at 3 and 4 months after maximum light show
double-peaked oxygen lines that we associate with departures from spherical
symmetry, as has been suggested for the inner ejecta of a number of SN Ib
cores.Comment: Accepted to ApJ, v3 contains more data than v2 and more references,
conclusions not significantly changed, 28 pages in emulateapj, 17 figure
La fabrique d’un corpus archéologique : l’expérience du projet ICARE (Iconographie et Collections d'Anthropologie de Rennes)
International audienc
Truncating Mutations in the Adhesion G Protein-Coupled Receptor G2 Gene ADGRG2 Cause an X-Linked Congenital Bilateral Absence of Vas Deferens
International audienceIn 80% of infertile men with obstructive azoospermia caused by a congenital bilateral absence of the vas deferens (CBAVD), mutations are identified in the cystic fibrosis transmembrane conductance regulator gene (CFTR). For the remaining 20%, the origin of the CBAVD is unknown. A large cohort of azoospermic men with CBAVD was retrospectively reassessed with more stringent selection criteria based on consistent clinical data, complete description of semen and reproductive excurrent ducts, extensive CFTR testing, and kidney ultrasound examination. To maximize the phenotypic prioritization, men with CBAVD and with unilateral renal agenesis were considered ineligible for the present study. We performed whole-exome sequencing on 12 CFTR-negative men with CBAVD and targeted sequencing on 14 additional individuals. We identified three protein-truncating hemizygous mutations, c.1545dupT (p.Glu516Ter), c.2845delT (p.Cys949AlafsTer81), and c.2002_2006delinsAGA (p.Leu668ArgfsTer21), in ADGRG2, encoding the epididymal- and efferent-ducts-specific adhesion G protein-coupled receptor G2, in four subjects, including two related individuals with X-linked transmission of their infertility. Previous studies have demonstrated that Adgrg2-knockout male mice develop obstructive infertility. Our study confirms the crucial role of ADGRG2 in human male fertility and brings new insight into congenital obstructive azoospermia pathogenesis. In men with CBAVD who are CFTR-negative, ADGRG2 testing could allow for appropriate genetic counseling with regard to the X-linked transmission of the molecular defect
Patients with KCNH1-related intellectual disability without distinctive features of Zimmermann-Laband/Temple-Baraitser syndrome
International audienceDe novo missense variants in KCNH1 encoding Kv10.1 are responsible for two clinically recognisable phenotypes: Temple-Baraitser syndrome (TBS) and Zimmermann-Laband syndrome (ZLS). The clinical overlap between these two syndromes suggests that they belong to a spectrum of KCNH1 -related encephalopathies. Affected patients have severe intellectual disability (ID) with or without epilepsy, hypertrichosis and distinctive features such as gingival hyperplasia and nail hypoplasia/aplasia (present in 20/23 reported cases). We report a series of seven patients with ID and de novo pathogenic KCNH1 variants identified by whole-exome sequencing or an epilepsy gene panel in whom the diagnosis of TBS/ZLS had not been first considered. Four of these variants, p.(Thr294Met), p.(Ala492Asp), p.(Thr493Asn) and p.(Gly496Arg), were located in the transmembrane domains S3 and S6 of Kv10.1 and one, p.(Arg693Gln), in its C-terminal cyclic nucleotide-binding homology domain (CNBHD). Clinical reappraisal by the referring clinical geneticists confirmed the absence of the distinctive gingival and nail features of TBS/ZLS. Our study expands the phenotypical spectrum of KCNH1 -related encephalopathies to individuals with an attenuated extraneurological phenotype preventing a clinical diagnosis of TBS or ZLS. This subtype may be related to recurrent substitutions of the Gly496, suggesting a genotype–phenotype correlation and, possibly, to variants in the CNBHD domain