Molecular characterization of a Rhodococcus jostii RHA1 γ-butyrolactone(-like) signalling molecule and its main biosynthesis gene gblA

Rhodococcus genome sequence analysis has revealed a surprisingly large (and unexplored) potential for the production of secondary metabolites. Also, putative γ-butyrolactone gene clusters have been identified in some Rhodococci. These signalling molecules are known to regulate secondary metabolism in Streptomyces. This work provides evidence for synthesis of a γ-butyrolactone(-like) molecule by Rhodococci (RJB), the first report in the Rhodococcus genus. The Rhodococcus jostii RHA1 RJB molecule was detected by a reporter system based on the γ-butyrolactone receptor protein (ScbR) of Streptomyces coelicolor. This RJB is structurally identical to 6-dehydro SCB2, the predicted precursor of the S. coelicolor γ-butyrolactone SCB2. The R. jostii RHA1 key RJB biosynthesis gene was identified (gblA): Deletion of gblA resulted in complete loss of RJB synthesis whereas higher RJB levels were detected when gblA was overexpressed. Interaction of the RJB molecule with ScbR indicates that communication may occur between these two Actinomycete genera in their natural habitat. Furthermore, RJB may provide a highly relevant tool for awakening cryptic secondary metabolic gene clusters in Rhodococci. This study provides preliminary evidence that R. jostii RHA1 indeed synthesizes diffusible molecules with antimicrobial activity, but a possible role for RJB in this remains to be established

Alpine forbs rely on different photoprotective strategies during spring snowmelt

Snowmelt in alpine ecosystems brings ample water, and together with above-freezing temperatures, initiates plant growth. In this scenario, rapid activation of photosynthesis is essential for a successful life-history strategy. But, strong solar radiation in late spring enhances the risk of photodamage, particularly before photosynthesis is fully functional. We compared the photoprotective strategy of five alpine forbs: one geophyte not particularly specialised in subnival life (Crocus albiflorus) and four wintergreens differing in their degree of adaptation to subnival life, from least to most specialised: Gentiana acaulis, Geum montanum, Homogyne alpina and Soldanella alpina. We used distance to the edge of snow patches as a proxy to study time-dependent changes after melting. We postulated that the photoprotective response of snowbed specialists would be stronger than of more-generalist alpine meadow species. F-v/F-m was relatively low across wintergreens and even lower in the geophyte C. albiflorus. This species also had the largest xanthophyll-cycle pool and lowest tocopherol and flavonoid glycoside contents. After snow melting, all the species progressively activated ETR, but particularly the intermediate snowbed species G. acaulis and G. montanum. The photoprotective responses after snowmelt were idiosyncratic: G. montanum rapidly accumulated xanthophyll-cycle pigments, tocopherol and flavonoid glycosides; while S. alpina showed the largest increase in plastochromanol-8 and chlorophyll contents and the greatest changes in optical properties. Climate warming scenarios might shift the snowmelt date and consequently alter the effectiveness of photoprotection mechanisms, potentially changing the fitness outcome of the different strategies adopted by alpine forbs.Peer reviewe

Factores psicosociales y síndrome de burnout en médicos generales de Tepic, Nayarit (México)

Objetivo: Analizar los factores psicosociales que se asocian al síndrome de burnout en los médicos generales que laboran para una institución pública de salud en Tepic, Nayarit (México). Material y métodos: El estudio fue transversal analítico. La población la conformaron 97 médicos generales de manera voluntaria y bajo consentimiento informado. Para captar la información se emplearon dos instrumentos: la guía de identificación de factores psicosociales del Instituto Mexicano del Seguro Social y la escala de “Maslach Burnout Inventory (MBI)”. Resultados: La prevalencia global para los factores psicosociales fue del 23.7% y del 32% para el síndrome de burnout. Se obtuvieron asociaciones significativas entre algunas áreas de los factores psicosociales con diferentes dimensiones del síndrome de burnout. Se demostró evidencia significativa entre ambas escalas, con un OR de 2.70, IC=1.02-4.30 y p= 0.0441. Conclusiones: Los médicos probablemente manifiestan el síndrome de burnout debido a la exigencia que implica  velar la salud y el bienestar de las personas, adecuar las áreas laborales y organización del trabajo y las tareas podría ser una estrategia importante

Symbiosis at its limits: ecophysiological consequences of lichenization to the genus Prasiola in Antarctica

Lichens represent a symbiotic relationship between at least one fungal and one photosynthetic partner. The association between the lichen-forming fungus Mastodia tessellata (Verrucariaceae) and different species of Prasiola (Trebouxiophyceae) has an amphipolar distribution and represents a unique case study for the understanding of lichen symbiosis because of the macroalgal nature of the photobiont, the flexibility of the symbiotic interaction and the co-existence of free-living and lichenized forms in the same microenvironment. In this context, we aimed to (1) characterize the photosynthetic performance of co-occurring populations of free-living and lichenized Prasiola and (2) assess the effect of the symbiosis on water relations in Prasiola, including its tolerance of desiccation and its survival and performance under sub-zero temperatures

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Bacterial natural products: Prediction, regulation and characterization of biosynthetic gene clusters in Actinobacteria

Secondary metabolites are produced by many microbes. They are not essential for life, but may provide a competitive advantage in the natural environment. Antibiotics are an important example, crucial agents in the human health system, widely used to combat infectious diseases. In view of the emergence of (multi)antibiotic resistant pathogenic bacteria in recent years, there is an urgent need to discover new and effective antibiotics. Improvements in DNA sequencing techniques, and bioinformatics tools to analyze genome sequences, showed that microorganisms potentially can produce many more compounds than initially thought. Most of these compounds are not produced under laboratory conditions (cryptic biosynthetic gene clusters). This PhD thesis analyzed different strategies to identify and produce new secondary metabolites (antibiotics). Focus was on the genus Streptomyces, producing most of the antibiotics currently used in medicine, and on the genus Rhodococcus, which had hardly been studied. Synthesis of the blue pigment indigoidine and the tunicamycin-like antibiotics from Streptomyces clavuligerus ATCC 27064 was analyzed in detail. This thesis also reports an analysis of the genome sequences of 20 different Rhodococcus strains, revealing an impressive diversity of (novel) secondary metabolite gene clusters. Remarkably, the -butyrolactone signalling system, known to control antibiotic synthesis in various Streptomyces strains, was also present in Rhodococcus jostii RHA1, and characterized. This system thus may allow inter-generic communication to occur. This thesis therefore gives important insights in the (regulation of) secondary metabolism in S. clavuligerus ATCC 27064 and members of the Rhodococcus genus

A Multidisciplinary Approach to Unraveling the Natural Product Biosynthetic Potential of a Streptomyces Strain Collection Isolated from Leaf-Cutting Ants

The rapid emergence of bacterial resistance to antibiotics has urged the need to find novel bioactive compounds against resistant microorganisms. For that purpose, different strategies are being followed, one of them being exploring secondary metabolite production in microorganisms from uncommon sources. In this work, we have analyzed the genome of 12 Streptomyces sp. strains of the CS collection isolated from the surface of leaf-cutting ants of the Attini tribe and compared them to four Streptomyces model species and Pseudonocardia sp. Ae150A_Ps1, which shares the ecological niche with those of the CS collection. We used a combination of phylogenetics, bioinformatics and dereplication analysis to study the biosynthetic potential of our strains. 51.5% of the biosynthetic gene clusters (BGCs) predicted by antiSMASH were unknown and over half of them were strain-specific, making this strain collection an interesting source of putative novel compounds