Feed Regime Slightly Modifies the Bacterial but Not the Fungal Communities in the Intestinal Mucosal Microbiota of Cobia Fish (Rachycentron canadum).

The bacterial community of the intestinal microbiota influences many host functions, and similar effects have been recently reported for the fungal community (mycobiota). Cobia is a tropical fish that has been studied for its potential in marine aquaculture. However, the study of its bacterial community has been underreported and the mycobiota has not been investigated. We analyzed the gut bacterial and fungal profile present in the intestinal mucosa of reared adult cobias fed two diets (frozen fish pieces (FFPs) and formulated feed (FF)) for 4 months by sequencing the 16S rRNA (V3-V4) and internal transcribed spacer-2 (ITS2) regions using Illumina NovaSeq 6000. No significant differences in the alpha diversity of the bacterial community were observed, which was dominated by the phyla Proteobacteria (~96%) and Firmicutes (~1%). Cobia fed FF showed higher abundance of 10 genera, mainly UCG-002 (Family Oscillospiraceae) and Faecalibacterium, compared to cobia fed FFPs, which showed higher abundance of 7 genera, mainly Methylobacterium-Methylorubrum and Cutibacterium. The inferred bacterial functions were related to metabolism, environmental information processing and cellular processes; and no differences were found between diets. In mycobiota, no differences were observed in the diversity and composition of cobia fed the two diets. The mycobiota was dominated by the phyla Ascomycota (~88%) and Basidiomycota (~11%). This is the first study to describe the gut bacterial and fungal communities in cobia reared under captive conditions and fed on different diets and to identify the genus Ascobulus as a new member of the core fish mycobiota.

Selection of Autochthonous Yeasts Isolated from the Intestinal Tracts of Cobia Fish (Rachycentron canadum) with Probiotic Potential.

Some yeast strains have been proposed as probiotics to improve the health of cultured fish. Cobia is a tropical benthopelagic fish species with potential for marine aquaculture; however, one of the main limitations to its large-scale production is the high mortality of fish larvae. In this study, we evaluated the probiotic potential of autochthonous yeasts from the intestines of cobia. Thirty-nine yeast isolates were recovered from the intestinal mucosa of 37 adult healthy cobia by culture methods. Yeasts were identified by sequencing of the ITS and D1/D2 regions of the 28S rRNA gene and typed by RAPD-PCR using the M13 primer. Yeast strains with unique RAPD patterns were characterized in terms of their cell biomass production ability; anti-Vibrio, enzymatic, and hemolytic activity; biofilm production; hydrophobicity; autoaggregation; polyamine production; safety; and protection of cobia larvae against saline stress. Candida haemuloni C27 and Debaryomyces hansenii C10 and C28 were selected as potential probiotics. They did not affect the survival of larvae and showed biomass production >1 g L-1, hydrophobicity >41.47%, hemolytic activity γ, and activity in more than 8 hydrolytic enzymes. The results suggest that the selected yeast strains could be considered as potential probiotic candidates and should be evaluated in cobia larvae.

Effect of EARLY administration of DEXamethasone in patients with COVID-19 pneumonia without acute hypoxemic respiratory failure and risk of development of acute respiratory distress syndrome (EARLY-DEX COVID-19): study protocol for a randomized controlled trial.

BACKGROUND: Corticosteroids are one of the few drugs that have shown a reduction in mortality in coronavirus disease 2019 (COVID-19). In the RECOVERY trial, the use of dexamethasone reduced 28-day mortality compared to standard care in hospitalized patients with suspected or confirmed COVID-19 requiring supplemental oxygen or invasive mechanical ventilation. Evidence has shown that 30% of COVID-19 patients with mild symptoms at presentation will progress to acute respiratory distress syndrome (ARDS), particularly patients in whom laboratory inflammatory biomarkers associated with COVID-19 disease progression are detected. We postulated that dexamethasone treatment in hospitalized patients with COVID-19 pneumonia without additional oxygen requirements and at risk of progressing to severe disease might lead to a decrease in the development of ARDS and thereby reduce death. METHODS/DESIGN: This is a multicenter, randomized, controlled, parallel, open-label trial testing dexamethasone in 252 adult patients with COVID-19 pneumonia who do not require supplementary oxygen on admission but are at risk factors for the development of ARDS. Risk for the development of ARDS is defined as levels of lactate dehydrogenase > 245 U/L, C-reactive protein > 100 mg/L, and lymphocyte count of < 0.80 × 109/L. Eligible patients will be randomly assigned to receive either dexamethasone or standard of care. Patients in the dexamethasone group will receive a dose of 6 mg once daily during 7 days. The primary outcome is a composite of the development of moderate or more severe ARDS and all-cause mortality during the 30-day period following enrolment. DISCUSSION: If our hypothesis is correct, the results of this study will provide additional insights into the management and progression of this specific subpopulation of patients with COVID-19 pneumonia without additional oxygen requirements and at risk of progressing to severe disease. TRIAL REGISTRATION: ClinicalTrials.gov NCT04836780. Registered on 8 April 2021 as EARLY-DEX COVID-19.

Methods to Evaluate Bacterial Motility and Its Role in Bacterial-Host Interactions.

Bacterial motility is a widespread characteristic that can provide several advantages for the cell, allowing it to move towards more favorable conditions and enabling host-associated processes such as colonization. There are different bacterial motility types, and their expression is highly regulated by the environmental conditions. Because of this, methods for studying motility under realistic experimental conditions are required. A wide variety of approaches have been developed to study bacterial motility. Here, we present the most common techniques and recent advances and discuss their strengths as well as their limitations. We classify them as macroscopic or microscopic and highlight the advantages of three-dimensional imaging in microscopic approaches. Lastly, we discuss methods suited for studying motility in bacterial-host interactions, including the use of the zebrafish model.

Effect of corticosteroids in patients with COVID-19 early stage pneumonia and risk of disease progression: An uncharted territory.

Corticosteroids are one of the few drugs that have shown a reduction in mortality in coronavirus disease 2019 (COVID-19). In the RECOVERY trial, the use of dexamethasone reduced 28-day mortality compared to standard care in hospitalized patients with suspected or confirmed COVID-19 requiring supplemental oxygen or invasive mechanical ventilation. No benefit in patients not requiring respiratory support at randomization was observed. However, we believe that the use of corticosteroids in patients with COVID-19 pneumonia might not be subject to a decision based solely on oxygen needs. Evidence has shown that 30% of COVID-19 patients in its initial phases will progress to acute respiratory distress syndrome, particularly patients in whom laboratory inflammatory biomarkers associated with COVID-19 disease progression are detected. We postulated that corticosteroids in patients with COVID-19 in its initial phases and risk of progressing to severe disease might lead to a decrease in the development of acute respiratory distress syndrome, and thereby reduce death.

Damage response protein 1 (Dap1) functions in the synthesis of carotenoids and sterols in Xanthophyllomyces dendrorhous.

Cytochrome P450s (P450s) are heme-containing proteins involved in several cellular functions, including biosynthesis of steroidal hormones, detoxification of xenobiotic compounds, among others. Damage response protein 1 (Dap1) has been described as a positive regulator of P450s through protein-protein interactions in organisms such as Schizosaccharomyces pombe. Three P450s in the carotenogenic yeast Xanthophyllomyces dendrorhous have thus far been characterized: Cyp51 and Cyp61, which are involved in ergosterol biosynthesis, and CrtS (astaxanthin synthase), which is involved in biosynthesis of the carotenoid astaxanthin. In this work, we describe the X. dendrorhous DAP1 gene, deletion of which affected yeast pigmentation by decreasing the astaxanthin fraction and increasing the ß-carotene (a substrate of CrtS) fraction, which is consistent with the known role of CrtS. We found that the proportion of ergosterol was also decreased in the Δdap1 mutant. However, even though the fractions of the end products of these two pathways (the synthesis of carotenoids and sterols) were decreased in the Δdap1 mutant, the transcript levels of genes from the P450 systems involved were higher than those in the wild-type strain. We demonstrate that Dap1 coimmunoprecipitates with these three P450s, suggesting that Dap1 interacts with these three proteins. We propose that Dap1 regulates the synthesis of astaxanthin and ergosterol in X. dendrorhous, probably by regulating the P450s involved in both biosynthetic pathways at the protein level. This work suggests a new role for Dap1 in the regulation of carotenoid biosynthesis in X. dendrorhous.

Microbiota composition and susceptibility to florfenicol and oxytetracycline of bacterial isolates from mussels (Mytilus spp.) reared on different years and distance from salmon farms.

Chilean aquaculture mainly produces salmonids and molluscs. Salmonid production has been questioned by its excessive use of antimicrobials. This study aimed to investigate the bacterial microbiota composition of Mytilus spp. cultivated near salmonid farms and to determine the minimum inhibitory concentration (MIC) to florfenicol and oxytetracycline of its culturable bacteria. Seven Mytilus farming sites classified according to their proximity to salmon farms as close (CSF) or distant (DSF) were sampled in two years. We analyzed Mytilus microbiota composition through culture-independent methods, and isolated culturable bacteria, and identified those isolates with MIC values ≥ 64 µg mL-1 to florfenicol or oxytetracycline. Results revealed that the alpha diversity was affected by sampling year but not by Mytilus farming site location or its interaction. Nevertheless, in 2018, we observed a significant negative correlation between the alpha diversity of Mytilus microbiota in each farm sites and the tonnes of florfenicol reported for each phytosanitary management area. We detected significant differences in beta diversity and relative abundance of specific bacterial taxa in Mytilus microbiota depending on the proximity to salmon farms and years. A higher proportion of isolates with MIC values ≥ 64 µg mL-1 to both antibiotics was detected in 2019 compared to 2018, but not significant differences were detected according to Mytilus farming site location. However, in 2019, isolates from CSF sites showed higher MIC values for both antibiotics than those from DSF. Bacterial genera corresponding to isolates with MIC values ≥ 64 µg mL-1 represented a low proportion of Mytilus microbiota identified with the culture-independent approach, reflecting the need to implement new methodologies in the study of antimicrobial resistance. These results suggest that the proximity to salmonid farms and sampling year influence the Mytilus microbiota and MIC values of their bacterial isolates; however, other environmental variables should be considered in further studies.

Vulneración de derechos humanos en las movilizaciones de octubre de 2019 en Chile / Violation of human rights in the mobilizations of October 2019 in Chile

La revuelta popular de octubre de 2019 en Chile ha visibilizado nuevamente el tema de las vulneraciones de los derechos humanos en el contexto de movilizaciones masivas. En cuanto a daños en la salud de la población, se reportaron numerosas lesiones oculares por proyectiles de impacto cinético y uso de bombas lacrimógenas como proyectiles contra las personas, generando un brote de lesiones oculares inédito en el mundo. Existió un uso excesivo de armas químicas y no se han comunicado todos los químicos utilizados. El impacto en salud mental, sobre todo de la población que vivió en dictadura en los años 1970, es incierto, y la atención de salud se vio desbordada en las áreas geográficas más vulnerables. Es urgente establecer un sistema oportuno y transparente de vigilancia de este tipo de lesiones y conocer todos los compuestos químicos usados como lacrimógenos, así como la composición de los balines y los proyectiles. (AU)

Chile's October 2019 popular revolt has again made human rights violations visible in the context of mass mobilizations. In terms of damage to the population's health, multiple eye injuries produced by kinetic impact projectiles and tear bombs against people were reported, leading to an outbreak of unpublished eye injuries worldwide. There was excessive use of chemical weapons, and the totality of the chemicals used has not been transparent. The impact on mental health, especially of the population who lived during dictatorship in the 1970s, is uncertain and, health care was overwhelmed in the most vulnerable geographic areas. It is urgent to establish a timely and transparent system for monitoring such lesions and transparent all chemical compounds in teartearing and the composition of kinetic impact projectiles. (AU)

Probiotic Yeasts and Vibrio anguillarum Infection Modify the Microbiome of Zebrafish Larvae.

The host microbiome plays an essential role in health and disease. Microbiome modification by pathogens or probiotics has been poorly explored especially in the case of probiotic yeasts. Next-generation sequencing currently provides the best tools for their characterization. Debaryomyces hansenii 97 (D. hansenii 97) and Yarrowia lipolytica 242 (Y. lipolytica 242) are yeasts that protect wildtype zebrafish (Danio rerio) larvae against a Vibrio anguillarum (V. anguillarum) infection, increasing their survival rate. We investigate the effect of these microorganisms on the microbiome and neutrophil response (inflammation) in zebrafish larvae line Tg(Bacmpx:GFP) i114. We postulated that preinoculation of larvae with yeasts would attenuate the intestinal neutrophil response and prevent modification of the larval microbiome induced by the pathogen. Microbiome study was performed by sequencing the V3-V4 region of the 16S rRNA gene and prediction of metabolic pathways by Piphillin in conventionally raised larvae. Survival and the neutrophil response were both evaluated in conventional and germ-free conditions. V. anguillarum infection resulted in higher neutrophil number in the intestinal area compared to non-infected larvae in both conditions. In germ-free conditions, infected larvae pre-inoculated with yeasts showed fewer neutrophil numbers than infected larvae. In both conditions, only D. hansenii 97 increased the survival of infected larvae. Beta diversity of the microbiota was modified by V. anguillarum and both yeasts, compared to non-inoculated larvae. At 3 days post-infection, V. anguillarum modified the relative abundance of 10 genera, and pre-inoculation with D. hansenii 97 and Y. lipolytica 242 prevented the modification of 5 and 6 of these genera, respectively. Both yeasts prevent the increase of Ensifer and Vogesella identified as negative predictors for larval survival (accounting for 40 and 27 of the variance, respectively). In addition, yeast pre-inoculation prevents changes in some metabolic pathways altered by V. anguillarum's infection. These results suggest that both yeasts and V. anguillarum can shape the larval microbiota configuration in the early developmental stage of D. rerio. Moreover, modulation of key taxa or metabolic pathways of the larval microbiome by yeasts can be associated with the survival of infected larvae. This study contributes to the understanding of yeast-pathogen-microbiome interactions, although further studies are needed to elucidate the mechanisms involved.

Cultivable Yeast Microbiota from the Marine Fish Species Genypterus chilensis and Seriolella violacea.

Because of its outstanding biological and industrial importance, many efforts have been made to characterize the mycobiota of new environments and their biochemical and biotechnological potentials. Gut mycobiota can be a source of novel yeasts with the potential to be used as probiotics or have industrial applications. In this work, we characterized two as-yet unexplored yeast communities from the intestinal content of the cultured marine Chilean fishes Genypterus chilensis (G. chilensis) and Seriolella violacea (S. violacea). Yeasts were isolated through culture, identified by sequencing their ITS region, and characterized their enzymatic profile with API®ZYM. Rhodotorula mucilaginosa was identified in both fish species. For the first time, Candida palmioleophila, Candida pseudorugosa, Cystobasidium slooffiae, and a member of the Yamadazyma genus were also identified and described as part of the normal fish gut-microbiota. Furthermore, the diverse enzymatic profile exhibited by some of these isolates suggests that it may be possible to develop novel applications for them, such as new probiotics and other biotechnological applications.

Impact of Systemic Corticosteroids on Mortality in Older Adults With Critical COVID-19 Pneumonia.

BACKGROUND: The most susceptible population group to critical and fatal coronavirus disease 2019 (COVID-19) is older adults. In severe acute respiratory syndrome coronavirus 2 infection, the host immune response is thought to play a key role in the pathophysiological effects of lung damage. Therefore, corticosteroid therapy could modulate inflammation-mediated pulmonary injury and thereby reduce progression to severe respiratory failure and death. The aim of this study was to analyze the safety and clinical efficacy of corticosteroid therapy in older adults with severe COVID-19 pneumonia. METHOD: We reviewed the clinical records of confirmed COVID-19 patients aged 75 years or older admitted to our hospital over a 3-month period (March 1-May 31, 2020). A total of 143 patients were included in the study cohort. From 2 April, 2020, in accordance with World Health Organization guidance on COVID-19, our hospital protocol added corticosteroid for COVID-19 treatment. We compared in-hospital mortality among patients with critical COVID-19 who received corticosteroids therapy and those who did not. RESULTS: In total, 88 patients (61.5%) were treated with corticosteroids, and 55 patients (38.4%) were not. Both groups were similar in baseline characteristics. The median age was 85 years (interquartile range: 82-89), and 61.5% (88/143) were male. In-hospital mortality was lower in the corticosteroid group (68.2%) compared with patients in the noncorticosteroid group (81.8%). Treatment with corticosteroids was an independent survival factor (hazard ratio: 0.61; 95% CI: 0.41-0.93; p = .006). CONCLUSIONS: In critically ill older adults with COVID-19 pneumonia, the use of corticosteroid treatment resulted in lower mortality without severe adverse events.

[Violation of human rights in the mobilizations of October 2019 in Chile]. / Vulneración de derechos humanos en las movilizaciones de octubre de 2019 en Chile.

Chile's October 2019 popular revolt has again made human rights violations visible in the context of mass mobilizations. In terms of damage to the population's health, multiple eye injuries produced by kinetic impact projectiles and tear bombs against people were reported, leading to an outbreak of unpublished eye injuries worldwide. There was excessive use of chemical weapons, and the totality of the chemicals used has not been transparent. The impact on mental health, especially of the population who lived during dictatorship in the 1970s, is uncertain and, health care was overwhelmed in the most vulnerable geographic areas. It is urgent to establish a timely and transparent system for monitoring such lesions and transparent all chemical compounds in tear-tearing and the composition of kinetic impact projectiles.

Sterol regulatory element-binding protein Sre1 regulates carotenogenesis in the red yeast Xanthophyllomyces dendrorhous.

Xanthophyllomyces dendrorhous is a basidiomycete yeast that produces carotenoids, mainly astaxanthin. Astaxanthin is an organic pigment of commercial interest due to its antioxidant and coloring properties. X. dendrorhous has a functional SREBP pathway, and the Sre1 protein is the SREBP homolog in this yeast. However, how sterol regulatory element (Sre)1 promotes the biosynthesis of sterols and carotenoids in X. dendrorhous is unknown. In this work, comparative RNA-sequencing analysis between modified X. dendrorhous strains that have an active Sre1 protein and the WT was performed to identify Sre1-dependent genes. In addition, Sre1 direct target genes were identified through ChIP combined with lambda exonuclease digestion (ChIP-exo) assays. SRE motifs were detected in the promoter regions of several Sre1 direct target genes and were consistent with the SREs described in other yeast species. Sre1 directly regulates genes related to ergosterol biosynthesis as well as genes related to the mevalonate (MVA) pathway, which synthesizes the building blocks of isoprenoids, including carotenoids. Two carotenogenic genes, crtE and crtR, were also identified as Sre1 direct target genes. Thus, carotenogenesis in X. dendrorhous is regulated by Sre1 through the regulation of the MVA pathway and the regulation of the crtE and crtR genes. As the crtR gene encodes a cytochrome P450 reductase, Sre1 regulates pathways that include cytochrome P450 enzymes, such as the biosynthesis of carotenoids and sterols. These results demonstrate that Sre1 is a sterol master regulator that is conserved in X. dendrorhous.

National Health Policy Reform for Primary Care in Chile: A Qualitative Analysis of the Health Program Documents.

Introduction: Chilean policy makers reformed the national health policy for primary health care (PHC), shifting from the traditional biomedical model to the integral family and community health model with a biopsychosocial approach, to guide the delivery of PHC throughout the country. Purpose: To evaluate the implementation of the national health policy for PHC through an analysis of the program documents for PHC; and to identify to what extent the national health policy is expressed in each program document, and across all the documents. Methods: A qualitative document analysis with a purposive sample of program documents for PHC. The Chilean Ministry of Health website was systematically searched between October and December 2018 to identify relevant program documents. Thematic and content analysis were performed to identify evidence of the biopsychosocial approach to care delivery with each program document, including the types of interactions between professionals that contribute to person-centered or fragmented care. Results: The study included 13 PHC program documents. Three themes and 10 categories emerged from the data. Most program justifications focused on the biopsychosocial approach to care while including biomedical interventions and supporting independent professional work. Only 4 of the 13 programs were consistent in the justification, interventions, and types of stated professional interactions: 2 from the biopsychosocial and 2 from the biomedical perspectives. Conclusion: In terms of the national health policy for PHC in Chile, interprofessional collaboration and person-centered care processes and practices were partially aligned with the written content of the health program documents. As such, policy makers and health sector leaders are advised to analyze draft health program documents for consistency in translating national health policies into the written communications that define the actualization of the care model in PHC and direct professionals how to provide PHC to individuals and families.

Metallopeptidase Stp1 activates the transcription factor Sre1 in the carotenogenic yeast Xanthophyllomyces dendrorhous.

Xanthophyllomyces dendrorhous is a basidiomycete yeast known as a natural producer of astaxanthin, a carotenoid of commercial interest because of its antioxidant properties. Recent studies indicated that X. dendrorhous has a functional SREBP pathway involved in the regulation of isoprenoid compound biosynthesis, which includes ergosterol and carotenoids. SREBP is a major regulator of sterol metabolism and homeostasis in mammals; characterization in fungi also provides information about its role in the hypoxia adaptation response and virulence. SREBP protease processing is required to activate SREBP pathway functions in fungi. Here, we identified and described the STP1 gene, which encodes a metallopeptidase of the M50 family involved in the proteolytic activation of the transcription factor Sre1 of the SREBP pathway, in X. dendrorhous We assessed STP1 function in Δstp1 strains derived from the wild-type and a mutant of ergosterol biosynthesis that overproduces carotenoids and sterols. Bioinformatic analysis of the deduced protein predicted the presence of characteristic features identified in homologs from mammals and fungi. The Δstp1 mutation decreased yeast growth in the presence of azole drugs and reduced transcript levels of Sre1-dependent genes. This mutation also negatively affected the carotenoid- and sterol-overproducing phenotype. Western blot analysis demonstrated that Sre1 was activated in the yeast ergosterol biosynthesis mutant and that the Δstp1 mutation introduced in this strain prevented Sre1 proteolytic activation. Overall, our results demonstrate that STP1 encodes a metallopeptidase involved in proteolytic activation of Sre1 in X. dendrorhous, contributing to our understanding of fungal SREBP pathways.

Urgent care centres reduce emergency department and primary care same-day visits: a natural experiment.

The aim of this study is to evaluate the impact of urgent care centres' (UCCs) implementation on emergency department (ED) and same-day visits in primary care in a Chilean public healthcare network. Quasi-experimental design study assessing changes in patient visits after UCC implementation in a local health district. Ten family health centres (FHC), nine UCCs and three EDs in the Talcahuano Health District, Chile. A total of 1 603 055 same-day visits to FHC, 1 528 319 visits to UCCs and 1 727 429 visits to EDs, monthly grouped, from 2008 to 2014. Data were obtained from the Monthly Statistical Register Database. We used quasi-experimental methods to evaluate the impact of UCC implementation on ED visits and same-day visits to FHC. We used a difference-in-difference analysis with seasonal adjustments to control potential confounders. We used a triple difference model to test for potential short-term effects. We used as an intervention a group of FHCs and EDs that implemented UCCs from 2008 to 2014 and, as a comparison group, the FHCs and EDs that implemented UCCs before that period. We observed a 5.70% (95% CI: -11.05 to -0.35) decrease in the same-day visits rate to FHCs and a 2.69% (95% CI: -3.96 to -1.43) reduction in ED visits after UCC implementation. The negative trend in same-day visits was more pronounced in children and adolescents (-14.18%; 95% CI: -20.10 to -8.25). The negative trend in ED visits was more pronounced in adult (-4.15%; 95% CI: -5.46 to -2.83) and elderly population (-2.24%; 95% CI: -4.00 to -0.48). We also confirmed that our results are not driven by transient short-term effects after the intervention. UCC implementation reduced ED visits. However, they also reduced same-day visits to primary care centres. This could have a negative impact on the quality of primary care provided.

Sterol Regulatory Element-Binding Protein (Sre1) Promotes the Synthesis of Carotenoids and Sterols in Xanthophyllomyces dendrorhous.

Xanthophyllomyces dendrorhous is a basidiomycete yeast that synthesizes carotenoids, mainly astaxanthin, which are of great commercial interest. Currently, there are many unknown aspects related to regulatory mechanisms on the synthesis of carotenoids in this yeast. Our recent studies showed that changes in sterol levels and composition resulted in upregulation of genes in the mevalonate pathway required for the synthesis of carotenoid precursors, leading to increased production of these pigments. Sterol Regulatory Element-Binding Proteins (SREBP), called Sre1 in yeast, are conserved transcriptional regulators of sterol homeostasis and other cellular processes. Given the results linking sterols and carotenoids, we investigated the role of SREBP in sterol and carotenoid synthesis in X. dendrorhous. In this study, we present the identification and functional characterization of the X. dendrorhous SRE1 gene, which encodes the transcription factor Sre1. The deduced protein has the characteristic features of SREBP/Sre1 and binds to consensus DNA sequences in vitro. RNA-seq analysis and chromatin-immunoprecipitation experiments showed that genes of the mevalonate pathway and ergosterol biosynthesis are directly regulated by Sre1. The sre1- mutation reduced sterol and carotenoid production in X. dendrorhous, and expression of the Sre1 N-terminal domain (Sre1N) increased carotenoid production more than twofold compared to wild-type. Overall, our results indicate that in X. dendrorhous transcriptional regulation of genes in the mevalonate pathway control production of the isoprenoid derivatives, carotenoids and sterol. Our results provide new insights into the conserved regulatory functions of SREBP/Sre1 and identify pointing to the SREBP pathway as a potential target to enhance carotenoid production in X. dendrorhous.

Characterization of the cytochrome P450 monooxygenase genes (P450ome) from the carotenogenic yeast Xanthophyllomyces dendrorhous.

BACKGROUND: The cytochromes P450 (P450s) are a large superfamily of heme-containing monooxygenases involved in the oxidative metabolism of an enormous diversity of substrates. These enzymes require electrons for their activity, and the electrons are supplied by NAD(P)H through a P450 electron donor system, which is generally a cytochrome P450 reductase (CPR). The yeast Xanthophyllomyces dendrorhous has evolved an exclusive P450-CPR system that specializes in the synthesis of astaxanthin, a carotenoid with commercial potential. For this reason, the aim of this work was to identify and characterize other potential P450 genes in the genome of this yeast using a bioinformatic approach. RESULTS: Thirteen potential P450-encoding genes were identified, and the analysis of their deduced proteins allowed them to be classified in ten different families: CYP51, CYP61, CYP5139 (with three members), CYP549A, CYP5491, CYP5492 (with two members), CYP5493, CYP53, CYP5494 and CYP5495. Structural analyses of the X. dendrorhous P450 proteins showed that all of them have a predicted transmembrane region at their N-terminus and have the conserved domains characteristic of the P450s, including the heme-binding region (FxxGxRxCxG); the PER domain, with the characteristic signature for fungi (PxRW); the ExxR motif in the K-helix region and the oxygen-binding domain (OBD) (AGxDTT); also, the characteristic secondary structure elements of all the P450 proteins were identified. The possible functions of these P450s include primary, secondary and xenobiotic metabolism reactions such as sterol biosynthesis, carotenoid synthesis and aromatic compound degradation. CONCLUSIONS: The carotenogenic yeast X. dendrorhous has thirteen P450-encoding genes having potential functions in primary, secondary and xenobiotic metabolism reactions, including some genes of great interest for fatty acid hydroxylation and aromatic compound degradation. These findings established a basis for future studies about the role of P450s in the carotenogenic yeast X. dendrorhous and their potential biotechnological applications.

Health policy in the concertación era (1990-2010): Reforms the chilean way.

The Chilean health system has experienced important transformations in the last decades with a neoliberal turn to privatization of the health insurance and healthcare market since the Pinochet reforms of the 1980s. During 20 years of center-left political coalition governments several reforms were attempted to regulate and reform such markets. This paper analyzes regulatory policies for the private health insurance and health care delivery market, adopted during the 1990-2010 period. A framework of variation in market types developed by Gingrich is adopted as analytical perspective. The set of policies advanced in this period could be expected to shift the responsibility of access to care from individuals to the collective and give control to the State or the consumers vis a vis producers. Nevertheless, the effect of the implemented reforms has been mixed. Regulations on private health insurers were ineffective in terms of shifting power to the consumer or the state. In contrast, the healthcare delivery market showed a trend of increasing payers' and consumers' control and the set of implemented reforms partially steered the market toward collective responsibility of access by creating a submarket of guaranteed services (AUGE) with lower copayments and fully funded services. Emerging unintended consequences of the adopted policies and potential explanations are discussed. In sum, attempts to use regulation to improve the collective dimension of the Chilean health system has enabled some progress, but several challenges had persisted.

Molecular Characterization and Functional Analysis of Cytochrome b5 Reductase (CBR) Encoding Genes from the Carotenogenic Yeast Xanthophyllomyces dendrorhous.

The eukaryotic microsomal cytochrome P450 systems consist of a cytochrome P450 enzyme (P450) and a cytochrome P450 redox partner, which generally is a cytochrome P450 reductase (CPR) that supplies electrons from NADPH. However, alternative electron donors may exist such as cytochrome b5 reductase and cytochrome b5 (CBR and CYB5, respectively) via, which is NADH-dependent and are also anchored to the endoplasmic reticulum. In the carotenogenic yeast Xanthophyllomyces dendrorhous, three P450-encoding genes have been described: crtS is involved in carotenogenesis and the CYP51 and CYP61 genes are both implicated in ergosterol biosynthesis. This yeast has a single CPR (encoded by the crtR gene), and a crtR- mutant does not produce astaxanthin. Considering that this mutant is viable, the existence of alternative cytochrome P450 electron donors like CBR and CYB5 could operate in this yeast. The aim of this work was to characterize the X. dendrorhous CBR encoding gene and to study its involvement in P450 reactions in ergosterol and carotenoid biosynthesis. Two CBRs genes were identified (CBR.1 and CBR.2), and deletion mutants were constructed. The two mutants and the wild-type strain showed similar sterol production, with ergosterol being the main sterol produced. The crtR- mutant strain produced a lower proportion of ergosterol than did the parental strain. These results indicate that even though one of the two CBR genes could be involved in ergosterol biosynthesis, crtR complements their absence in the cbr- mutant strains, at least for ergosterol production. The higher NADH-dependent cytochrome c reductase activity together with the higher transcript levels of CBR.1 and CYB5 in the crtR- mutant as well as the lower NADH-dependent activity in CBS-cbr.1- strongly suggest that CBR.1-CYB5 via participates as an alternative electron donor pathway for P450 enzymes involved in ergosterol biosynthesis in X. dendrorhous.