Towards a molecular understanding of symbiont function: Identification of a fungal gene for the degradation of xylan in the fungus gardens of leaf-cutting ants

<p>Abstract</p> <p>Background</p> <p>Leaf-cutting ants live in symbiosis with a fungus that they rear for food by providing it with live plant material. Until recently the fungus' main inferred function was to make otherwise inaccessible cell wall degradation products available to the ants, but new studies have shed doubt on this idea. To provide evidence for the cell wall degrading capacity of the attine ant symbiont, we designed PCR primers from conserved regions of known xylanase genes, to be used in PCR with genomic DNA from the symbiont as template. We also measured xylanase, cellulase and proteinase activities in the fungus gardens in order to investigate the dynamics of degradation activities.</p> <p>Results</p> <p>We cloned a xylanase gene from the mutualistic fungus of <it>Acromyrmex echinatior</it>, determined its protein sequence, and inserted it in a yeast expression vector to confirm its substrate specificity. Our results show that the fungus has a functional xylanase gene. We also show by lab experiments <it>in vivo </it>that the activity of fungal xylanase and cellulase is not evenly distributed, but concentrated in the lower layer of fungus gardens, with only modest activity in the middle layer where gongylidia are produced and intermediate activity in the newly established top layer. This vertical distribution appears to be negatively correlated with the concentration of glucose, which indicates a directly regulating role of glucose, as has been found in other fungi and has been previously suggested for the ant fungal symbiont.</p> <p>Conclusion</p> <p>The mutualistic fungus of <it>Acromyrmex echinatior </it>has a functional xylanase gene and is thus presumably able to at least partially degrade the cell walls of leaves. This finding supports a saprotrophic origin of the fungal symbiont. The observed distribution of enzyme activity leads us to propose that leaf-substrate degradation in fungus gardens is a multi-step process comparable to normal biodegradation of organic matter in soil ecosystems, but with the crucial difference that a single fungal symbiont realizes most of the steps that are normally provided by a series of microorganisms that colonize fallen leaves in a distinct succession.</p

Can The Business Model Of Handelsbanken Be An Archetype For Small And Medium Sized Banks? A Comparative Case Study

The Danish Banking sector faces increasing requirements regarding regulation and profitability, which especially threatens small and medium sized banks. This study analyzes whether the successful business model of Handelsbanken (The Handelsbanken Way) can serve as a blueprint for small and medium sized banks. We conduct a comparative case study by interviewing Handelsbanken and the disguised Danish Local Bank (DLB). The DLB is a representative example of small and medium sized Danish banks. This study is structured according to the frameworks from business model implementations and from implied organizational structures.Using the notion of Osterwalder and Pigneur (2010), this study reveals only minor differences in the business models of Handelsbanken and DLB. Despite the supposedly obvious advantages of The Handelsbanken Way, this study suggests that the financially troubled small and medium sized banks in Denmark will not necessarily benefit from the tactical choice of decentralization unless they incorporate specific adjustments. This study contributes to the existing theory if Handelsbankens approach to banking can improve the situation of financially troubled small and medium sized banks

Fungiculture in termites is associated with a mycolytic gut bacterial community

ABSTRACT Termites forage on a range of substrates, and it has been suggested that diet shapes the composition and function of termite gut bacterial communities. Through comparative analyses of gut metagenomes in nine termite species with distinct diets, we characterize bacterial community compositions and use peptide-based functional annotation method to determine biomass-degrading enzymes and the bacterial taxa that encode them. We find that fungus-growing termite guts have relatively more fungal cell wall-degrading enzyme genes, while wood-feeding termite gut communities have relatively more plant cell wall-degrading enzyme genes. Interestingly, wood-feeding termite gut bacterial genes code for abundant chitinolytic enzymes, suggesting that fungal biomass within the decaying wood likely contributes to gut bacterial or termite host nutrition. Across diets, the dominant biomass-degrading enzymes are predominantly coded for by the most abundant bacterial taxa, suggesting tight links between diet and gut community composition, with the most marked difference being the communities coding for the mycolytic capacity of the fungus-growing termite gut. IMPORTANCE Understanding functional capacities of gut microbiomes is important to improve our understanding of symbiotic associations. Here, we use peptide-based functional annotation to show that the gut microbiomes of fungus-farming termites code for a wealth of enzymes that likely target the fungal diet the termites eat. Comparisons to other termites showed that fungus-growing termite guts have relatively more fungal cell wall-degrading enzyme genes, whereas wood-feeding termite gut communities have relatively more plant cell wall-degrading enzyme genes. Across termites with different diets, the dominant biomass-degrading enzymes are predominantly coded for by the most abundant bacterial taxa, suggesting tight links between diet and gut community compositions

The fungal symbiont of <em>Acromyrmex</em> leaf-cutting ants expresses the full spectrum of genes to degrade cellulose and other plant cell wall polysaccharides

BACKGROUND: The fungus gardens of leaf-cutting ants are natural biomass conversion systems that turn fresh plant forage into fungal biomass to feed the farming ants. However, the decomposition potential of the symbiont Leucocoprinus gongylophorus for processing polysaccharides has remained controversial. We therefore used quantifiable DeepSAGE technology to obtain mRNA expression patterns of genes coding for secreted enzymes from top, middle, and bottom sections of a laboratory fungus-garden of Acromyrmex echinatior leaf-cutting ants. RESULTS: A broad spectrum of biomass-conversion-relevant enzyme genes was found to be expressed in situ: cellulases (GH3, GH5, GH6, GH7, AA9 [formerly GH61]), hemicellulases (GH5, GH10, CE1, GH12, GH74), pectinolytic enzymes (CE8, GH28, GH43, PL1, PL3, PL4), glucoamylase (GH15), α-galactosidase (GH27), and various cutinases, esterases, and lipases. In general, expression of these genes reached maximal values in the bottom section of the garden, particularly for an AA9 lytic polysaccharide monooxygenase and for a GH5 (endocellulase), a GH7 (reducing end-acting cellobiohydrolase), and a GH10 (xylanase), all containing a carbohydrate binding module that specifically binds cellulose (CBM1). Although we did not directly quantify enzyme abundance, the profile of expressed cellulase genes indicates that both hydrolytic and oxidative degradation is taking place. CONCLUSIONS: The fungal symbiont of Acromyrmex leaf-cutting ants can degrade a large range of plant polymers, but the conversion of cellulose, hemicellulose, and part of the pectin occurs primarily towards the end of the decomposition process, i.e. in the bottom section of the fungus garden. These conversions are likely to provide nutrients for the fungus itself rather than for the ants, whose colony growth and reproductive success are limited by proteins obtained from ingesting fungal gongylidia. These specialized hyphal tips are hardly produced in the bottom section of fungus gardens, consistent with the ants discarding old fungal biomass from this part of the garden. The transcripts that we found suggest that actively growing mycelium in the bottom of gardens helps to maintain an optimal water balance to avoid hyphal disintegration, so the ants can ultimately discard healthy rather than decaying and diseased garden material, and to buffer negative effects of varying availability and quality of substrate across the seasons

The effectiveness of parent training as a treatment for preschool attention-deficit/hyperactivity disorder : study protocol for a randomized controlled, multicenter trial of the new Forest Parenting Program in everyday clinical practice

Background: Parent training is recommended as the first-line treatment for attention-deficit/hyperactivity disorder (ADHD) in preschool children. The New Forest Parenting Programme (NFPP) is an evidence-based parenting program developed specifically to target preschool ADHD. Objective: The objective of this trial is to investigate whether the NFPP can be effectively delivered for children referred through official community pathways in everyday clinical practice. Methods: A multicenter randomized controlled parallel arm trial design is employed. There are two treatment arms, NFPP and treatment as usual. NFPP consists of eight individually delivered parenting sessions, where the child attends during three of the sessions. Outcomes are examined at three time points (T1, T2, T3): T1 (baseline), T2 (week 12, post intervention), and T3 (6 month follow/up). 140 children between the ages of 3-7, with a clinical diagnosis of ADHD, informed by the Development and Well Being Assessment, and recruited from three child and adolescent psychiatry departments in Denmark will take part. Randomization is on a 1: 1 basis, stratified for age and gender. Results: The primary endpoint is change in ADHD symptoms as measured by the Preschool ADHD-Rating Scale (ADHD-RS) by T2. Secondary outcome measures include: effects on this measure at T3 and T2 and T3 measures of teacher reported Preschool ADHD-RS scores, parent and teacher rated scores on the Strength & Difficulties Questionnaire, direct observation of ADHD behaviors during Child's Solo Play, observation of parent-child interaction, parent sense of competence, and family stress. Results will be reported using the standards set out in the Consolidated Standards of Reporting Trials Statement for Randomized Controlled Trials of nonpharmacological treatments. Conclusions: The trial will provide evidence as to whether NFPP is a more effective treatment for preschool ADHD than the treatment usually offered in everyday clinical practice

Cost effectiveness of adding budesonide/formoterol to tiotropium in COPD in four Nordic countries

Objective: Assess the cost effectiveness of budesonide/formoterol (BUD/FORM) Turbuhaler®+tiotropium (TIO) HandiHaler® vs. placebo (PBO)+TIO in patients with chronic obstructive pulmonary disease (COPD) eligible for inhaled corticosteroids/long-acting β2-agonists (ICS/LABA). Methods: The cost-effectiveness analysis was based on the 12-week, randomised, double-blind CLIMB trial. The study included 659 patients with pre-bronchodilator forced expiratory volume in 1 s ≤ 50% and ≥1 exacerbation requiring systemic glucocorticosteroids or antibiotics the preceding year. Patients received BUD/FORM 320/9 μg bid + TIO 18 μg qd or PBO bid + TIO 18 μg qd. Effectiveness was defined as the number of severe exacerbations (hospitalisation/emergency room visit/systemic glucocorticosteroids) avoided. A sub-analysis included antibiotics in the definition of an exacerbation. Resource use from CLIMB was combined with Danish (DKK), Finnish (€), Norwegian (NOK) and Swedish (SEK) unit costs (2010). The incremental cost-effectiveness ratios (ICERs) for BUD/FORM + TIO vs. PBO + TIO were estimated using descriptive statistics and uncertainty around estimates using bootstrapping. Analyses were conducted from the societal and healthcare perspectives in Denmark, Finland, Norway and Sweden. Results: From a societal perspective, the ICER was estimated at €174/severe exacerbation avoided in Finland while BUD/FORM + TIO was dominant in the other countries. From the healthcare perspective, ICERs were DKK 1580 (€212), €307 and SEK 1573 (€165) per severe exacerbation avoided for Denmark, Finland and Sweden, respectively, while BUD/FORM + TIO was dominant in Norway. Including antibiotics decreased ICERs by 8–15%. Sensitivity analyses showed that results were overall robust. Conclusion: BUD/FORM + TIO represents a clinical and economic benefit to health systems and society for the treatment of COPD in the Nordic countries.publishedVersio

The effectiveness of parent training as a treatment for preschool Attention-Deficit/Hyperactivity Disorder: study protocol for a randomized controlled, multicenter trial of the New Forest Parenting Program in everyday clinical practice

Background: Parent training is recommended as the first-line treatment for attention-deficit/hyperactivity disorder (ADHD) in preschool children. The New Forest Parenting Programme (NFPP) is an evidence-based parenting program developed specifically to target preschool ADHD.Objective: The objective of this trial is to investigate whether the NFPP can be effectively delivered for children referred through official community pathways in everyday clinical practice.Methods: A multicenter randomized controlled parallel arm trial design is employed. There are two treatment arms, NFPP and treatment as usual. NFPP consists of eight individually delivered parenting sessions, where the child attends during three of the sessions. Outcomes are examined at three time points (T1, T2, T3): T1 (baseline), T2 (week 12, post intervention), and T3 (6 month follow/up). 140 children between the ages of 3-7, with a clinical diagnosis of ADHD, informed by the Development and Well Being Assessment, and recruited from three child and adolescent psychiatry departments in Denmark will take part. Randomization is on a 1:1 basis, stratified for age and gender.Results: The primary endpoint is change in ADHD symptoms as measured by the Preschool ADHD-Rating Scale (ADHD-RS) by T2. Secondary outcome measures include: effects on this measure at T3 and T2 and T3 measures of teacher reported Preschool ADHD-RS scores, parent and teacher rated scores on the Strength &amp; Difficulties Questionnaire, direct observation of ADHD behaviors during Child’s Solo Play, observation of parent-child interaction, parent sense of competence, and family stress. Results will be reported using the standards set out in the Consolidated Standards of Reporting Trials Statement for Randomized Controlled Trials of nonpharmacological treatments.Conclusions: The trial will provide evidence as to whether NFPP is a more effective treatment for preschool ADHD than the treatment usually offered in everyday clinical practice.Trial Registration: ClinicalTrials.gov NCT01684644; https://clinicaltrials.gov/ct2/show/NCT01684644?term= NCT01684644&amp;rank=

Lower <i>versus</i> higher oxygenation targets in critically ill patients with severe hypoxaemia:secondary Bayesian analysis to explore heterogeneous treatment effects in the Handling Oxygenation Targets in the Intensive Care Unit (HOT-ICU) trial

BACKGROUND: In the Handling Oxygenation Targets in the Intensive Care Unit (HOT-ICU) trial, a lower (8 kPa) vs a higher (12 kPa) PaO(2) target did not affect mortality amongst critically ill adult patients. We used Bayesian statistics to evaluate any heterogeneity in the effect of oxygenation targets on mortality between different patient groups within the HOT-ICU trial. METHODS: We analysed 90-day all-cause mortality using adjusted Bayesian logistic regression models, and assessed heterogeneous treatment effects according to four selected baseline variables using both hierarchical models of subgroups and models with interactions on the continuous scales. Results are presented as mortality probability (%) and relative risk (RR) with 95% credibility intervals (CrI). RESULTS: All 2888 patients in the intention-to-treat cohort of the HOT-ICU trial were included. The adjusted 90-day mortality rates were 43.0% (CrI: 38.3–47.8%) and 42.3% (CrI: 37.7–47.1%) in the lower and higher oxygenation groups, respectively (RR 1.02 [CrI: 0.93–1.11]), with 36.5% probability of an RR <1.00. Analyses of heterogeneous treatment effects suggested a dose–response relationship between baseline norepinephrine dose and increased mortality with the lower oxygenation target, with 95% probability of increased mortality associated with the lower oxygenation target as norepinephrine doses increased. CONCLUSIONS: A lower oxygenation target was unlikely to affect overall mortality amongst critically ill adult patients with acute hypoxaemic respiratory failure. However, our results suggest an increasing mortality risk for patients with a lower oxygen target as the baseline norepinephrine dose increases. These findings warrant additional investigation. CLINICAL TRIAL REGISTRATION: NCT03174002

Explainable artificial intelligence model to predict acute critical illness from electronic health records

We developed an explainable artificial intelligence (AI) early warning score (xAI-EWS) system for early detection of acute critical illness. While maintaining a high predictive performance, our system explains to the clinician on which relevant electronic health records (EHRs) data the prediction is grounded. Acute critical illness is often preceded by deterioration of routinely measured clinical parameters, e.g., blood pressure and heart rate. Early clinical prediction is typically based on manually calculated screening metrics that simply weigh these parameters, such as Early Warning Scores (EWS). The predictive performance of EWSs yields a tradeoff between sensitivity and specificity that can lead to negative outcomes for the patient. Previous work on EHR-trained AI systems offers promising results with high levels of predictive performance in relation to the early, real-time prediction of acute critical illness. However, without insight into the complex decisions by such system, clinical translation is hindered. In this letter, we present our xAI-EWS system, which potentiates clinical translation by accompanying a prediction with information on the EHR data explaining it