Searching for swept-up hydrogen and helium in the late-time spectra of 11 nearby Type Ia supernovae

The direct detection of a stellar system that explodes as a Type Ia supernova (SN Ia) has not yet been successful. Various indirect methods have been used to investigate SN Ia progenitor systems but none have produced conclusive results. A prediction of single-degenerate models is that H- (or He-) rich material from the envelope of the companion star should be swept up by the SN ejecta in the explosion. Seven SNe Ia have been analysed to date looking for signs of H-rich material in their late-time spectra and none were detected. We present results from new late-time spectra of 11 SNe Ia obtained at the Very Large Telescope using XShooter and FORS2. We present the tentative detection of Hα emission for SN 2013ct, corresponding to ∼0.007 M_⊙ of stripped/ablated companion star material (under the assumptions of the spectral modelling). This mass is significantly lower than expected for single-degenerate scenarios, suggesting that >0.1 M_⊙ of H-rich is present but not observed. We do not detect Hα emission in the other 10 SNe Ia. This brings the total sample of normal SNe Ia with non-detections (<0.001–0.058 M_⊙) of H-rich material to 17 events. The simplest explanation for these non-detections is that these objects did not result from the explosion of a CO white dwarf accreting matter from a H-rich companion star via Roche lobe overflow or symbiotic channels. However, further spectral modelling is needed to confirm this. We also find no evidence of He-emission features, but models with He-rich companion stars are not available to place mass limits.

Characterization of IGH locus breakpoints in multiple myeloma indicates a subset of translocations appear to occur in pregerminal center B cells.

Translocations in myeloma are thought to occur solely in mature B cells in the germinal center through class switch recombination (CSR). We used a targeted captured technique followed by massively parallel sequencing to determine the exact breakpoints in both the immunoglobulin heavy chain (IGH) locus and the partner chromosome in 61 presentation multiple myeloma samples. The majority of samples (62%) have a breakpoint within the switch regions upstream of the IGH constant genes and are generated through CSR in a mature B cell. However, the proportion of CSR translocations is not consistent between cytogenetic subgroups. We find that 100% of t(4;14) are CSR-mediated; however, 21% of t(11;14) and 25% of t(14;20) are generated through DH-JH recombination activation gene-mediated mechanisms, indicating they occur earlier in B-cell development at the pro-B-cell stage in the bone marrow. These 2 groups also generate translocations through receptor revision, as determined by the breakpoints and mutation status of the segments used in 10% and 50% of t(11;14) and t(14;20) samples, respectively. The study indicates that in a significant number of cases the translocation-based etiological events underlying myeloma may arise at the pro-B-cell hematological progenitor cell level, much earlier in B-cell development than was previously thought.

Over 30% of patients with splenic marginal zone lymphoma express the same immunoglobulin heavy variable gene: ontogenetic implications.

We performed an immunogenetic analysis of 345 IGHV-IGHD-IGHJ rearrangements from 337 cases with primary splenic small B-cell lymphomas of marginal-zone origin. Three immunoglobulin (IG) heavy variable (IGHV) genes accounted for 45.8% of the cases (IGHV1-2, 24.9%; IGHV4-34, 12.8%; IGHV3-23, 8.1%). Particularly for the IGHV1-2 gene, strong biases were evident regarding utilization of different alleles, with 79/86 rearrangements (92%) using allele (*)04. Among cases more stringently classified as splenic marginal-zone lymphoma (SMZL) thanks to the availability of splenic histopathological specimens, the frequency of IGHV1-2(*)04 peaked at 31%. The IGHV1-2(*)04 rearrangements carried significantly longer complementarity-determining region-3 (CDR3) than all other cases and showed biased IGHD gene usage, leading to CDR3s with common motifs. The great majority of analyzed rearrangements (299/345, 86.7%) carried IGHV genes with some impact of somatic hypermutation, from minimal to pronounced. Noticeably, 75/79 (95%) IGHV1-2(*)04 rearrangements were mutated; however, they mostly (56/75 cases; 74.6%) carried few mutations (97-99.9% germline identity) of conservative nature and restricted distribution. These distinctive features of the IG receptors indicate selection by (super)antigenic element(s) in the pathogenesis of SMZL. Furthermore, they raise the possibility that certain SMZL subtypes could derive from progenitor populations adapted to particular antigenic challenges through selection of VH domain specificities, in particular the IGHV1-2(*)04 allele.

EspZ of enteropathogenic and enterohemorrhagic Escherichia coli regulates type III secretion system protein translocation

UNLABELLED: Translocation of effector proteins via a type III secretion system (T3SS) is a widespread infection strategy among Gram-negative bacterial pathogens. Each pathogen translocates a particular set of effectors that subvert cell signaling in a way that suits its particular infection cycle. However, as effector unbalance might lead to cytotoxicity, the pathogens must employ mechanisms that regulate the intracellular effector concentration. We present evidence that the effector EspZ controls T3SS effector translocation from enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli. Consistently, an EPEC espZ mutant is highly cytotoxic. Following ectopic expression, we found that EspZ inhibited the formation of actin pedestals as it blocked the translocation of Tir, as well as other effectors, including Map and EspF. Moreover, during infection EspZ inhibited effector translocation following superinfection. Importantly, while EspZ of EHEC O157:H7 had a universal "translocation stop" activity, EspZ of EPEC inhibited effector translocation from typical EPEC strains but not from EHEC O157:H7 or its progenitor, atypical EPEC O55:H7. We found that the N and C termini of EspZ, which contains two transmembrane domains, face the cytosolic leaflet of the plasma membrane at the site of bacterial attachment, while the extracellular loop of EspZ is responsible for its strain-specific activity. These results show that EPEC and EHEC acquired a sophisticated mechanism to regulate the effector translocation.

IMPORTANCE: Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are important diarrheal pathogens responsible for significant morbidity and mortality in developing countries and the developed world, respectively. The virulence strategy of EPEC and EHEC revolves around a conserved type III secretion system (T3SS), which translocates bacterial proteins known as effectors directly into host cells. Previous studies have shown that when cells are infected in two waves with EPEC, the first wave inhibits effector translocation by the second wave in a T3SS-dependent manner, although the factor involved was not known. Importantly, we identified EspZ as the effector responsible for blocking protein translocation following a secondary EPEC infection. Interestingly, we found that while EspZ of EHEC can block protein translocation from both EPEC and EHEC strains, EPEC EspZ cannot block translocation from EHEC. These studies show that EPEC and EHEC employ a novel infection strategy to regulate T3SS translocation.

The Status of Multi-Dimensional Core-Collapse Supernova Models

Models of neutrino-driven core-collapse supernova explosions have matured considerably in recent years. Explosions of low-mass progenitors can routinely be simulated in 1D, 2D, and 3D. Nucleosynthesis calculations indicate that these supernovae could be contributors of some lighter neutron-rich elements beyond iron. The explosion mechanism of more massive stars remains under investigation, although first 3D models of neutrino-driven explosions employing multi-group neutrino transport have become available. Together with earlier 2D models and more simplified 3D simulations, these have elucidated the interplay between neutrino heating and hydrodynamic instabilities in the post-shock region that is essential for shock revival. However, some physical ingredients may still need to be added/improved before simulations can robustly explain supernova explosions over a wide range of progenitors. Solutions recently suggested in the literature include uncertainties in the neutrino rates, rotation, and seed perturbations from convective shell burning. We review the implications of 3D simulations of shell burning in supernova progenitors for the ‘perturbations-aided neutrino-driven mechanism,’ whose efficacy is illustrated by the first successful multi-group neutrino hydrodynamics simulation of an 18 solar mass progenitor with 3D initial conditions. We conclude with speculations about the impact of 3D effects on the structure of massive stars through convective boundary mixing.

The Last Minutes of Oxygen Shell Burning in a Massive Star

We present the first 3D simulation of the last minutes of oxygen shell burning in an 18 solar mass supernova progenitor up to the onset of core collapse. A moving inner boundary is used to accurately model the contraction of the silicon and iron core according to a 1D stellar evolution model with a self-consistent treatment of core deleptonization and nuclear quasi-equilibrium. The simulation covers the full solid angle to allow the emergence of large-scale convective modes. Due to core contraction and the concomitant acceleration of nuclear burning, the convective Mach number increases to ~0.1 at collapse, and an l=2 mode emerges shortly before the end of the simulation. Aside from a growth of the oxygen shell from 0.51 to 0.56 solar masses due to entrainment from the carbon shell, the convective flow is reasonably well described by mixing length theory, and the dominant scales are compatible with estimates from linear stability analysis. We deduce that artificial changes in the physics, such as accelerated core contraction, can have precarious consequences for the state of convection at collapse. We argue that scaling laws for the convective velocities and eddy sizes furnish good estimates for the state of shell convection at collapse and develop a simple analytic theory for the impact of convective seed perturbations on shock revival in the ensuing supernova. We predict a reduction of the critical luminosity for explosion by 12--24% due to seed asphericities for our 3D progenitor model relative to the case without large seed perturbations.

Estilos Educativos Parentais (EMBU-A), Sintomatologia Depressiva/Ansiosa, Stress e Autoestima, numa Amostra de Adolescentes

Introdução. Os estilos educativos parentais enquanto clima educativo geral apresentam um forte impacto em diferentes resultados desenvolvimentais (e.g., sintomatologia depressiva/ansiosa e auto estima) da criança/jovem. Podem ser estudados de um ponto de vista dimensional, considerando, por exemplo, as dimensões Controlo/Sobreproteção e Suporte, ou categorial, seguindo, por exemplo, a abordagem de Baumrind, e Maccoby e Martin. Neste estudo pretendemos: verificar se existem diferenças por género e idade, nas dimensões Suporte Emocional, Sobreproteção e Rejeição (EMBU-A) (cada progenitor separadamente), na sintomatologia depressiva/ansiosa e na auto estima; avaliar se existem diferenças nas dimensões do EMBU-A, entre progenitores, na amostra total e por género; explorar associações entre as variáveis centrais do estudo (estilos educativos, sintomatologias e auto estima) e variáveis sociodemográficas, também nas três amostras; explorar diferenças entre quatro grupos criados (Pai-Filho, Pai-Filha; Mãe-Filho e Mãe-Filha) nas dimensões do EMBU-A; combinando a Sobreproteção e o Suporte Emocional (EMBU-A), e definindo os estilos educativos parentais autoritário, autoritativo, permissivo e negligente, calcular a prevalência dos mesmos na nossa amostra (por Pai e por Mãe) e explorar as suas associações com as sintomatologias e com a auto estima (separadamente, por progenitor). Metodologia. A nossa amostra é constituída por 284 adolescentes (idade média = 14,5; DP = 1,68; raparigas, n = 171, 60,2%). Todos preencheram um protocolo composto por um questionário sociodemográfico, pela Rosenberg Self- Esteem Scale (RSES), pelo DASS-21 e pelo Parental Rearing Style Questionnaire for use with Adolescents (EMBU-A/A). Resultados. De salientar o facto de os adolescentes percecionarem a mãe como apresentando valores mais elevados em todas as dimensões do EMBU-A, por comparação com o pai. Da mesma forma, ainda que com diferentes padrões de associação conforme o género, é de salientar a associação entre níveis maiores de Suporte emocional e níveis mais baixos de sintomatologia depressiva/ansiosa e stress, e a associação entre as dimensões Sobreproteção e Rejeição e níveis superiores desses resultados. Uma mais baixa escolaridade do pai associa-se a menor Suporte emocional e uma maior escolaridade da mãe a maior Sobreproteção. Uma díade constituída por progenitor e adolescente do género masculino apresenta resultados inferiores em todas as dimensões do EMBU-A, por comparação com díades formadas por mãe-filho/filha. O estilo Autoritativo é o mais prevalente na nossa amostra (em ambos os progenitores) e o estilo Autoritário é aquele que se associa a pontuações mais elevadas de psicopatologia e a uma menor auto estima. Discussão. De uma forma, genérica os resultados seguem de perto a literatura e revelam a associação entre valores mais elevados na dimensão Suporte emocional e níveis mais baixos de psicopatologia e stress, e a associação entre as dimensões Sobreproteção e Rejeição e níveis superiores desses resultados. Igualmente, o estilo educativo Autoritário está claramente associado a piores resultados nessas mesmas variáveis. São discutidas algumas implicações, no que toca a programas psicoeducativos/educação parental. / Introduction. As a general educational environment, parental rearing styles have a strong impact in different outcomes of development of the child or teenager (e.g. symptoms of depression/ anxiety and self-esteem). These can be studied from a dimensional point of view considering for example the dimensions Control/Overprotection and Support or from a categorical point of view following for example the approach of Baumrind and Maccoby and Martin. This study aims at checking whether there are differences of gender and age in the dimensions of Emotional Support, Overprotection and Rejection (EMBU-A) (each parent separately) in depressive symptoms/anxiety and self esteem; assessing whether there are differences in the dimensions of the EMBU-A, between parents in the total sample and by gender; exploring associations between the study’s main variables (rearing styles, symptomatology and self esteem) and sociodemographic variables, also in the three samples; exploring differences between the four groups created (Father-Son, Father-Daughter, Mother-Son and Mother-Daughter) in the dimensions of the EMBU-A, combining Overprotection and Emotional Support(EMBU-A) and defining the authoritarian, authoritative, indulgent, and neglectful parental rearing styles. The aim is also to estimate the prevalence of these in our sample (by Father and Mother) and explore their associations to the symptomatology and self esteem (separately, per parent). Methodology. Our sample is composed of 284 teenagers (average age = 14,5; DP = 1,68; girls, n = 171, 60,2%). All participants filled in a protocol of questionnaires consisting of a set of socio demographic questions by Rosenberg Self- Esteem Scale (RSES), by DASS-21 and by Parental Rearing Style Questionnaire for use with Adolescents (EMBU-A/A). Outcomes. It is important to emphasize the fact that teenagers perceive their mother as having higher values in all the EMBU-A dimensions compared to their father. In the same way, though with different patterns of association according to gender, it is important to emphasize the association of higher levels of Emotional Support and lower levels of depressive/anxious symptomathology and stress and the association of Overprotection and Rejection and higher levels of those outcomes. A father’s lower level of education is associated to a lower Emotional Support while a mother’s higher level of education is associated to a greater Overprotection. A dyad composed of male parent and male teenager presents lower outcomes in all EMBU-A dimensions if compared to dyads composed of mother-son/daughter. The authoritative style is the most prevalent in our sample (in both parents) and the authoritarian style is the one associated to higher scores of psychopathology and lower levels of self esteem. Debate. In general, the outcomes closely follow the literature review and reveal the association of higher values in the Emotional Support dimension and lower levels of psychopathology and stress and also the association of the dimensions of Overprotection and Rejection and higher levels of those outcomes. Equally, the authoritarian rearing style is clearly associated to the worst outcomes in those same variables. Some implications are discussed as far as psychoeducational programmes and parental rearing are concerned.

Sonic hedgehog signaling regulates mode of cell division of early cerebral cortex progenitors and increases

The morphogen Sonic Hedgehog (SHH) plays a critical role in the development of different tissues. In the central nervous system, SHH is well known to contribute to the patterning of the spinal cord and separation of the brain hemispheres. In addition, it has recently been shown that SHH signaling also contributes to the patterning of the telencephalon and establishment of adult neurogenic niches. In this work, we investigated whether SHH signaling influences the behavior of neural progenitors isolated from the dorsal telencephalon, which generate excitatory neurons and macroglial cells in vitro. We observed that SHH increases proliferation of cortical progenitors and generation of astrocytes, whereas blocking SHH signaling with cyclopamine has opposite effects. In both cases, generation of neurons did not seem to be affected. However, cell survival was broadly affected by blockade of SHH signaling. SHH effects were related to three different cell phenomena: mode of cell division, cell cycle length and cell growth. Together, our data in vitro demonstrate that SHH signaling controls cell behaviors that are important for proliferation of cerebral cortex progenitors, as well as differentiation and survival of neurons and astroglial cells.

Proliferative Defects and Formation of a Double Cortex in Mice Lacking Mltt4 and Cdh2 in the Dorsal Telencephalon

Radial glial cells (RGCs) in the ventricular neuroepithelium of the dorsal telencephalon are the progenitor cells for neocortical projection neurons and astrocytes. Here we showthatthe adherens junction proteins afadin and CDH2 are criticalforthe control of cell proliferation in the dorsal telencephalon and for the formation of its normal laminar structure. Inactivation of afadin or CDH2 in the dorsal telenceph-alon leads to a phenotype resembling subcortical band heterotopia, also known as “double cortex,” a brain malformation in which heterotopic gray matter is interposed between zones of white matter. Adherens junctions between RGCs are disrupted in the mutants, progenitor cells are widely dispersed throughout the developing neocortex, and their proliferation is dramatically increased. Major subtypes of neocortical projection neurons are generated, but their integration into cell layers is disrupted. Our findings suggest that defects in adherens junctions components in mice massively affects progenitor cell proliferation and leads to a double cortex-like phenotype.