Stellar populations in the center of barred spiral galaxies

We show observations obtained with the integral field spectrometer OASIS for the central regions of a sample of barred galaxies. The high spatial resolution of the instrument allows to distinguish various structures within these regions as defined by stellar populations of different ages and metallicities. From these data we obtain important clues about the star formation history. But we advise that, in order to obtain adequately the evolutionary sequence, a combination of chemical and synthesis models may be necessary.Comment: 4 pages, 2 figures, submitted to the IAU245 Symposium Formation and Evolution of Galaxy Bulge

La limite de l'ombre ; suivi de, Une archéologie de l'ordinaire

Le mémoire qui suit comporte deux parties distinctes et autonomes bien qu'on puisse les considérer comme complémentaires. En dépit du fait qu'y sont abordés des thèmes semblables, le traitement, les intentions et le ton de chaque partie diffèrent. La limite de l'ombre est un court roman qui raconte le quotidien sans événement d'un petit quartier. Y sont exposées les relations entre les trois principaux personnages: Patrick Dupuis, Solange Lemieux et Marc Arbour. La narration se développe autour de ce qui se cache, de ce qui demeure enfoui au cœur de leurs relations. Une large place est faite à la problématique de la cohabitation dans le rapport physique et géographique entre les personnages, des groupes de personnages, mais aussi entre les personnages, les animaux et les insectes. C'est, d'une certaine manière, un roman stratifié qui actualise quelques interactions possibles entre les différentes couches narratives. Une archéologie de l'ordinaire est un essai qui traite explicitement des phénomènes d'apparition et de disparition, des collectionneurs et des collections, ainsi que de la cohabitation. Quelques figures importantes comme Jacques de Tonnancour, Georges Didi-Huberman et Maurice Merleau-Ponty jalonnent et orientent la réflexion. \ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Apparitions, Disparitions, Collections, Cohabitation

Bactericidal Effect of Tomatidine-Tobramycin Combination against Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa Is Enhanced by Interspecific Small-Molecule Interactions.

This study investigated the antibacterial activity of the plant alkaloid tomatidine (TO) against Staphylococcus aureus grown in presence of Pseudomonas aeruginosa. Since the P. aeruginosa exoproduct 4-hydroxy-2-heptylquinoline-N-oxide (HQNO) is known to cause respiratory deficiency in S. aureus and that respiratory-deficient S. aureus are known to be hypersensitive to TO, we performed kill kinetics of TO (8 mug/ml) against S. aureus in co-culture with P. aeruginosa. Kill kinetics were also carried out using P. aeruginosa mutants deficient in the production of different exoproducts and quorum sensing-related compounds. After 24h in co-culture, TO increased the killing of S. aureus by 3.4 log10 CFU/ml in comparison to that observed in a co-culture without TO. The effect of TO was abolished when S. aureus was in co-culture with the lasR-/rhlR-, pqsA-, pqsL- or lasA- mutant of P. aeruginosa. The bactericidal effect of TO against S. aureus in co-culture with the pqsL- mutant was restored by supplemental HQNO. In a S. aureus mono-culture, the combination of HQNO and TO was bacteriostatic, indicating that the pqsL- mutant produced an additional factor required for the bactericidal effect. The bactericidal activity of TO was also observed against a tobramycin-resistant methicillin-resistant S. aureus (MRSA) in co-culture with P. aeruginosa and addition of tobramycin significantly suppressed the growth of both microorganisms. TO shows a strong bactericidal effect against S. aureus when co-cultured with P. aeruginosa. The combination of TO and tobramycin may represent a new treatment approach for cystic fibrosis patients frequently co-colonized by MRSA and P. aeruginosa

Commentary: reconstructing four centuries of temperature-induced coral bleaching on the great barrier reef

Coral reefs are spectacular ecosystems found along tropical coastlines where they provide goods and services to hundreds of millions of people. While under threat from local factors, coral reefs are increasingly susceptible to ocean warming from anthropogenic climate change. One of the signature disturbances is the large-scale, and often deadly, breakdown of the symbiosis between corals and dinoflagellates. This is referred to as mass coral bleaching and often causes mass mortality. The first scientific records of mass bleaching date to the early 1980s (Hoegh-Guldberg et al., 2017). Kamenos and Hennige (2018, hereafter KH18), however, claim to show that mass coral bleaching is not a recent phenomenon, and has occurred regularly over the past four centuries (1572–2001) on the Great Barrier Reef (GBR), Australia. They support their claim by developing a putative proxy for coral bleaching that uses the suggested relationship between elevated sea surface temperatures (SSTs) and reduced linear extension rates of 44 Porites spp. coral cores from 28 GBR reefs. If their results are correct, then mass coral bleaching events have been a frequent feature for hundreds of years in sharp contrast to the vast majority of scientific evidence. There are, however, major flaws in the KH18 methodology. Their use of the Extended Reconstructed Sea Surface Temperature (ERSST) dataset (based on ship and buoy observations) for reef temperatures from 1854 to 2001, ignores the increasing unreliability of these data which become sparse, less rigorous, and more interpolated going back in time. To demonstrate how the quality of these data degrades, we plot the average number of SST observations per month that contribute to each 200 x 200 km ERSST pixel (Figure 1A, black line). Note that from 1854 to 1900 the four ERSST pixels used by KH18 averaged only 0.85 observations per month, and 82% of these months had no observations at all. Given the heterogeneous nature of SST at local and regional levels, using such broad-scale data as ERSST, is likely to produce substantial errors at reef scales (Figure 1A, red line prior to 1900)

SARS-CoV-2 spike antigen-specific B cell and antibody responses in pre-vaccination period COVID-19 convalescent males and females with or without post-covid condition

BackgroundFollowing SARS-CoV-2 infection a significant proportion of convalescent individuals develop the post-COVID condition (PCC) that is characterized by wide spectrum of symptoms encompassing various organs. Even though the underlying pathophysiology of PCC is not known, detection of viral transcripts and antigens in tissues other than lungs raise the possibility that PCC may be a consequence of aberrant immune response to the viral antigens. To test this hypothesis, we evaluated B cell and antibody responses to the SARS-CoV-2 antigens in PCC patients who experienced mild COVID-19 disease during the pre-vaccination period of COVID-19 pandemic.MethodsThe study subjects included unvaccinated male and female subjects who developed PCC or not (No-PCC) after clearing RT-PCR confirmed mild COVID-19 infection. SARS-CoV-2 D614G and omicron RBD specific B cell subsets in peripheral circulation were assessed by flow cytometry. IgG, IgG3 and IgA antibody titers toward RBD, spike and nucleocapsid antigens in the plasma were evaluated by ELISA.ResultsThe frequency of the B cells specific to D614G-RBD were comparable in convalescent groups with and without PCC in both males and females. Notably, in females with PCC, the anti-D614G RBD specific double negative (IgD-CD27-) B cells showed significant correlation with the number of symptoms at acute of infection. Anti-spike antibody responses were also higher at 3 months post-infection in females who developed PCC, but not in the male PCC group. On the other hand, the male PCC group also showed consistently high anti-RBD IgG responses compared to all other groups.ConclusionsThe antibody responses to the spike protein, but not the anti-RBD B cell responses diverge between convalescent males and females who develop PCC. Our findings also suggest that sex-related factors may also be involved in the development of PCC via modulating antibody responses to the SARS-CoV-2 antigens

Historical Temperature Variability Affects Coral Response to Heat Stress

Coral bleaching is the breakdown of symbiosis between coral animal hosts and their dinoflagellate algae symbionts in response to environmental stress. On large spatial scales, heat stress is the most common factor causing bleaching, which is predicted to increase in frequency and severity as the climate warms. There is evidence that the temperature threshold at which bleaching occurs varies with local environmental conditions and background climate conditions. We investigated the influence of past temperature variability on coral susceptibility to bleaching, using the natural gradient in peak temperature variability in the Gilbert Islands, Republic of Kiribati. The spatial pattern in skeletal growth rates and partial mortality scars found in massive Porites sp. across the central and northern islands suggests that corals subject to larger year-to-year fluctuations in maximum ocean temperature were more resistant to a 2004 warm-water event. In addition, a subsequent 2009 warm event had a disproportionately larger impact on those corals from the island with lower historical heat stress, as indicated by lower concentrations of triacylglycerol, a lipid utilized for energy, as well as thinner tissue in those corals. This study indicates that coral reefs in locations with more frequent warm events may be more resilient to future warming, and protection measures may be more effective in these regions

SARS-CoV-2 spike antigen-specific B cell and antibody responses in pre-vaccination period COVID-19 convalescent males and females with or without post-covid condition

Background Following SARS-CoV-2 infection a significant proportion of convalescent individuals develop the post-COVID condition (PCC) that is characterized by wide spectrum of symptoms encompassing various organs. Even though the underlying pathophysiology of PCC is not known, detection of viral transcripts and antigens in tissues other than lungs raise the possibility that PCC may be a consequence of aberrant immune response to the viral antigens. To test this hypothesis, we evaluated B cell and antibody responses to the SARS-CoV-2 antigens in PCC patients who experienced mild COVID-19 disease during the pre-vaccination period of COVID-19 pandemic. Methods The study subjects included unvaccinated male and female subjects who developed PCC or not (No-PCC) after clearing RT-PCR confirmed mild COVID-19 infection. SARS-CoV-2 D614G and omicron RBD specific B cell subsets in peripheral circulation were assessed by flow cytometry. IgG, IgG3 and IgA antibody titers toward RBD, spike and nucleocapsid antigens in the plasma were evaluated by ELISA. Results The frequency of the B cells specific to D614G-RBD were comparable in convalescent groups with and without PCC in both males and females. Notably, in females with PCC, the anti-D614G RBD specific double negative (IgD-CD27-) B cells showed significant correlation with the number of symptoms at acute of infection. Anti-spike antibody responses were also higher at 3 months post-infection in females who developed PCC, but not in the male PCC group. On the other hand, the male PCC group also showed consistently high anti-RBD IgG responses compared to all other groups. Conclusions The antibody responses to the spike protein, but not the anti-RBD B cell responses diverge between convalescent males and females who develop PCC. Our findings also suggest that sex-related factors may also be involved in the development of PCC via modulating antibody responses to the SARS-CoV-2 antigens