Physiological responses of six temperate tree species to water limitation

Abstract Direct evidence for the link between stem diameter variations (SDV) and the daily canopy water status, i.e. daily water potentials (Ψ), is rare, particularly for tall trees. It thus remains unclear up to what degree SDV readings are useful to estimate daily canopy Ψ. We measured SDV with point dendrometers at the stem base of tall, mature individuals of six European forest tree species in a near-natural temperate forest and compared them to daily canopy Ψ during the growing seasons of 2014 (wet) and 2015 (dry). SDV were de-trended for growth with two different approaches leading to the socalled tree water deficit (TWD). We found that midday Ψ can be predicted from TWD, independent of the growth-de-trending procedure to obtain TWD from SDV. Further, daily TWD was a better indicator for daily midday Ψ, particularly under dry conditions, than maximum daily shrinkage (MDS), another common quantity derived from SDV. Based on data from six temperate tree species, we conclude that TWD measured at the stem base is a consistent proxy for daily canopy midday Ψ of tall trees over the entire range of measured conditions. Keywords: drought, mature trees, maximum daily shrinkage, stem diameter variations, tree water deficit, water potentia

Higher expectations of teachers are not sufficient: How to take the next big step in social‐emotional teacher training

The growing interest in students' social‐emotional development, which is closely linked with the increasing efforts to reduce all forms of violence in schools, is a welcome development. However, if we are serious about furthering students' social‐emotional development with the same fervor as students' academic learning, we must provide teachers with the tools that enable them to meet these growing societal expectations. Most teachers at the secondary level are not trained to further students' social‐emotional development and are still primarily regarded, by themselves and others, as academic knowledge and skills conveyors. As a result, they are not prepared to respond to students' misbehavior and difficult group dynamics in ways that further students' social‐emotional development. Instead, they are forced to apply easy and quick‐to‐learn behavioral conditioning and punishment strategies that only manage behavior. Psychodynamic theory and empirical research suggest important limitations to this approach. Hence, I argue that teachers will be better prepared to meet these growing expectations in their work if they receive support in two ways. One, they need reliable feedback on those aspects of their daily interactions/routines with students that most strongly impact students' social‐emotional development. Student perception survey instruments are a particularly effective approach to collect such feedback, but contemporary instruments too strongly focus on behavior instead of underlying factors that determine behavior. Second, teachers need professional development training that takes into account and builds on such feedback. A particularly promising approach for such training is based on group‐analytic pedagogy.Peer Reviewe

Strain and bioprocess development for enhanced docosahexaenoic acid production in recombinant Yarrowia lipolytica

Engineered strains of the oleaginous yeast Y. lipolytica produce commercially attractive polyunsaturated fatty acids (PUFAs). In a pioneering study, strain Af4 was shown to produce docosahexaenoic acid (DHA), a major industrial PUFA, through expression of a myxobacterial PUFA synthase. This work aimed to increase the production of DHA in Y. lipolytica Po1h::Af4. In the first part, the impact of nutrients on the complex fermentation process was studied, resulting in different types of nutrient setups to trigger DHA production, including the comparison of different C-sources. In shake flask cultures, an improoved medium allowed to produce DHA up to a selectivity of 17% of TFAs. The second part tackled DHA overproduction on the genetic level by optimizing the expression of the PUFA cluster. A basic design, based on the commonly used pTEF, was sufficient to drive DHA production. Beneficially, the incorporation of the late-phase pminLEU2 plus additional genetic elements, such as UAS1B4 sequences, 5' introns, and intergenic spacers, DHA production increased up to 16-fold. The control elements acted synergistically, whereby the UAS1B4 elements generally increased expression, while the intron caused gene-specific effects. The synthetic producer strains were found genetically stable over 185 h of cultivation. A fed-batch fermentation, using the improved nutrient set-up with glucose as the carbon source yielded a DHA titer of 350 mg L-1 and a selectivity of 11% of DHA among TFAs.Gentechnisch veränderte Stämme der ölhaltigen Hefe Y. lipolytica produzieren kommerziell attraktive mehrfach ungesättigte Fettsäuren (PUFAs). In einer innovativen Studie wurde gezeigt, dass der Stamm Y. lipolytica Po1h::Af4 durch Expression einer myxobakteriellen PUFA-Synthase Docosahexaensäure (DHA), eine wichtige PUFA, produzieren kann. Ziel dieser Arbeit war es, die Produktion von DHA in Y. lipolytica zu steigern. Im ersten Teil wurde der Einfluss von Nährstoffen auf den komplexen Fermentationsprozess untersucht, was zu verschiedenen Arten von Medienkonfigurationen zur Auslösung der DHA-Produktion führte, einschließlich des Vergleichs verschiedener C-Quellen. Dies ermöglichte ein optimales Medium und die Produktion von DHA bis zu einer Selektivität von 17%. Der zweite Teil befasste sich mit der DHA-Überproduktion auf genetischer Ebene, indem die Expression des PUFA-Clusters optimiert wurde. Die Verwendung des minLEU2-Promotors und Einbau von UAS1B4-Sequenzen, 5'-Introns und intergenen Spacern konnte die DHA-Produktion um 16-fache im Vergleich zum Basisstamm gesteigert werden. Die genetischen Elemente wirkten synergistisch, wobei die UAS1B-Elemente die Expression generell erhöhten, während das Intron genspezifische Effekte verursachte. Die Produzenten blieben über 185 h Kultivierung genetisch stabil. Eine optimierte Fermentation unter Verwendung des verbesserten Mediums ergab einen DHA-Titer von 350 mg L-1 und eine Selektivität von 11% DHA anteilig am Gesamtlipids

Convergent Evolution of Hyperswarming Leads to Impaired Biofilm Formation in Pathogenic Bacteria

Most bacteria in nature live in surface-associated communities rather than planktonic populations. Nonetheless, how surface-associated environments shape bacterial evolutionary adaptation remains poorly understood. Here, we show that subjecting Pseudomonas aeruginosa to repeated rounds of swarming, a collective form of surface migration, drives remarkable parallel evolution toward a hyperswarmer phenotype. In all independently evolved hyperswarmers, the reproducible hyperswarming phenotype is caused by parallel point mutations in a flagellar synthesis regulator, FleN, which locks the naturally monoflagellated bacteria in a multiflagellated state and confers a growth rate-independent advantage in swarming. Although hyperswarmers outcompete the ancestral strain in swarming competitions, they are strongly outcompeted in biofilm formation, which is an essential trait for P. aeruginosa in environmental and clinical settings. The finding that evolution in swarming colonies reliably produces evolution of poor biofilm formers supports the existence of an evolutionary trade-off between motility and biofilm formation

Candida albicans Ethanol Stimulates Pseudomonas aeruginosa WspR-Controlled Biofilm Formation as Part of a Cyclic Relationship Involving Phenazines

In chronic infections, pathogens are often in the presence of other microbial species. For example, Pseudomonas aeruginosa is a common and detrimental lung pathogen in individuals with cystic fibrosis (CF) and co-infections with Candida albicans are common. Here, we show that P. aeruginosa biofilm formation and phenazine production were strongly influenced by ethanol produced by the fungus C. albicans. Ethanol stimulated phenotypes that are indicative of increased levels of cyclic-di-GMP (c-di-GMP), and levels of c-di-GMP were 2-fold higher in the presence of ethanol. Through a genetic screen, we found that the diguanylate cyclase WspR was required for ethanol stimulation of c-di-GMP. Multiple lines of evidence indicate that ethanol stimulates WspR signaling through its cognate sensor WspA, and promotes WspR-dependent activation of Pel exopolysaccharide production, which contributes to biofilm maturation. We also found that ethanol stimulation of WspR promoted P. aeruginosa colonization of CF airway epithelial cells. P. aeruginosa production of phenazines occurs both in the CF lung and in culture, and phenazines enhance ethanol production by C. albicans. Using a C. albicans adh1/adh1 mutant with decreased ethanol production, we found that fungal ethanol strongly altered the spectrum of P. aeruginosa phenazines in favor of those that are most effective against fungi. Thus, a feedback cycle comprised of ethanol and phenazines drives this polymicrobial interaction, and these relationships may provide insight into why co-infection with both P. aeruginosa and C. albicans has been associated with worse outcomes in cystic fibrosis. Author Summary : In many human infections, several species of microbes are often present. This is typically the case with the disease cystic fibrosis, characterized by thick mucus in the lungs that is colonized by bacteria and fungi. Here, we show evidence that interactions between the bacterium Pseudomonas aeruginosa and the fungus Candida albicans result in attributes of infection that are worse for the human host. We found that ethanol, such as that produced by C. albicans, causes increased levels of a signaling molecule in P. aeruginosa that promotes biofilm formation. Biofilm formation by P. aeruginosa is associated with infections that are more difficult to treat. Ethanol stimulated P. aeruginosa colonization of plastic surfaces and airway cells, and we identified components of this mechanism. Fungally-produced ethanol also changes the spectrum of phenazine toxins produced by P. aeruginosa, and phenazines are associated with worse lung function in people with cystic fibrosis. In light of the fact that phenazines interact with C. albicans to promote ethanol production, we propose a positive feedback loop between C. albicans and P. aeruginosa that contributes to worse disease. Our findings could have implications for the study and treatment of multi-species infections

Less Debt, More Equity: Lowering Student Debt While Closing the Black-White Wealth Gap

The dramatic increase in wealth inequality over the past several decades now forms the backdrop for many of today's most pressing public policy debates. Currently, the top 1 percent of U.S. households controls 42 percent of the nation's wealth, and nearly half of the wealth accumulated over the past 30 years has gone to the top 0.1 percent. Simultaneously, the wealth held by the bottom 90 percent of U.S. households continues to shrink, just as people of color are a growing percentage of the U.S. population. These trends have converged to produce a wealth divide that is apparent not just by class, but by race as well. The average white family owns $13 for every$1 owned by a typical Black family, and $10 for every$1 owned by the typical Latino family.This analysis uses the Racial Wealth Audit, a framework developed by the Institute on Assets and Social Policy (IASP) to assess the impact of public policy on the wealth gap between white and Black households. We use the framework to model the impact of various student debt relief policies to identify the approaches most likely to reduce inequities in wealth by race, as opposed to exacerbating existing inequities. We focus specifically on the Black-white wealth gap both because of the historic roots of inequality described above, and because student debt (in the form of borrowing rates and levels) seems to be contributing to wealth disparities between Black and white young adults, in particular

Synthesis of Low Abundant Vitamin D Metabolites and Assaying Their Distribution in Human Serum by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) as a New Tool for Diagnosis and Risk Prediction of Vitamin DRelated Diseases

This chapter provides an overview of versatile and efficient chemical syntheses of vitamin D derivatives by application of either linear or convergent synthesis approaches. Synthesis of the most relevant naturally occurring vitamin D metabolites and their deuterated counterparts to use as calibration and reference standards in LC-MS/MS assays is also shown. The chapter then summarizes the most important mass spectrometric approaches to quantify important vitamin D metabolites in human biofluids. In addition, new developments are described that are aimed at the pathobiological interpretation of the measured vitamin D metabolite distributions in various human diseases

The phenazine pyocyanin is a terminal signalling factor in the quorum sensing network of Pseudomonas aeruginosa

Certain members of the fluorescent pseudomonads produce and secrete phenazines. These heterocyclic, redox-active compounds are toxic to competing organisms, and the cause of these antibiotic effects has been the focus of intense research efforts. It is largely unknown, however, how pseudomonads themselves respond to – and survive in the presence of – these compounds. Using Pseudomonas aeruginosa DNA microarrays and quantitative RT-PCR, we demonstrate that the phenazine pyocyanin elicits the upregulation of genes/operons that function in transport [such as the resistance-nodulation-cell division (RND) efflux pump MexGHI-OpmD] and possibly in redox control (such as PA2274, a putative flavin-dependant monooxygenase), and downregulates genes involved in ferric iron acquisition. Strikingly, mexGHI-opmD and PA2274 were previously shown to be regulated by the PA14 quorum sensing network that controls the production of virulence factors (including phenazines). Through mutational analysis, we show that pyocyanin is the physiological signal for the upregulation of these quorum sensing-controlled genes during stationary phase and that the response is mediated by the transcription factor SoxR. Our results implicate phenazines as signalling molecules in both P. aeruginosa PA14 and PAO1

The importance of teacher-student relationships in classrooms with ‘difficult’ students: a multi-level moderation analysis of nine Berlin secondary schools

Meta-analyses suggest that instructional quality in the classroom and the quality of teacher-student relationships (TSR) predict positive social-emotional and achievement-related outcomes. Psychoanalytic theory asserts that positive teacher-student relationships are particularly important for outcomes in classrooms with more students with severe psychosocial difficulties. Hence, this study tests whether classrooms with more students with severe psychosocial difficulties have better social-emotional and achievement-related outcomes when teachers have been able to establish more positive relationships with their students. Hierarchical linear regression models use nested student survey data from 32 classrooms. Results only partially support the hypothesis and suggest that too many students with psychosocial difficulties might overwhelm even teachers with strong relationship-building skills, leading to detrimental outcomes.Peer Reviewe

The efficiency of EU anti-discrimination legislation

Die vorliegende Arbeit ist der Versuch, den Einfluss der EU-Anti-diskriminierungs-gesetzgebung zu evaluieren. Sie beginnt mit einer Untersuchung der Geschichte und Struktur von Antiziganismus, eine spezielle Form von Rassismus, die zu Diskriminierung und sozialer Exklusion von Roma und Sinti führt. Im Hauptteil die¬ser Arbeit werden zwei Dimensionen untersucht. Erstens, wie sich die EU-Antidiskri¬minierungsgesetzgebung seit dem Beginn der Europäischen Gemeinschaften ent¬wickelt hat, was eine Vorstellung davon vermittelt, welche Interessen welche Akteure in der Entwicklung von EU-Antidiskriminierungsgesetzgebung verfolgten. Es wird sich herausstellen, dass die Implementierung der 2000er Richtlinie zur Rassengleichheit durch den Erfolg von Rechtsextremismus in Europäischen Parlamenten ausgelöst wurde, und nicht durch das Elend diskriminierter, ethnischer und rassischer Minori¬täten. Zweitens, eine Untersuchung antiziganischer Diskriminierung und sozialer Ex¬klusion der Roma und Sinti innerhalb der Europäischen Union, um herauszufinden, ob die Implementierung der EU-Antidiskriminierungsgesetzgebung zu einer Verände¬rung bezüglich der diskriminierenden Behandlung von Roma und Sinti in der EU ge¬führt hat. Es wird sich weiterhin herausstellen, dass sich soziale Exklusion und anti-ziganische Diskriminierung seit der Implementierung der 2000er Richtlinie zur Rassengleichheit kaum verändert haben, was keine Überra¬schung angesichts der tiefen Verwurzlung von Antiziganismus in Europa ist.The diploma thesis at hand is the attempt to evaluate the impact of EU anti-discrimination law. It starts with an examination of the history and structure of anti-Gypsyism, a particular form of racism which leads to the discrimination and social exclusion of the Romani people from the beginning of their immigration to Europe. In the main part of this thesis, two dimensions will be examined. First, how EU anti-discrimination law evolved since the beginning of the European Communities, which will give an idea about which actors had what kind of interest in developing EU anti-discrimination law. It will be revealed that the implementation of the 2000 Racial Equality Directive was triggered by the political success of right extremism in European parliaments, and not the plight of discriminated ethnic/racial minorities. Second, an examination of anti-Gypsy discrimination and Romani social exclusion within the European Union, to find out whether the implementation of EU anti-discrimination law has led to a change of the discriminatory treatment of Romanies in the EU. It will turn out that social exclusion and anti-Gypsy discrimination hardly changed since the implementation of the 2000 Racial Equality Directive, which is not unexpected in face of the deep-rootedness of anti-Gypsyism in Europe