Comparative expression analysis of Shox2 -deficient embryonic stem cell-derived sinoatrial node-like cells

The homeodomain transcription factor Shox2 controls the development and function of the native cardiac pacemaker, the sinoatrial node (SAN).Moreover, SHOX2 mutations have been associatedwith cardiac arrhythmias in humans. For detailed examination of Shox2-dependent developmentalmechanisms in SAN cells, we established a murine embryonic stem cell (ESC)-based model using Shox2 as a molecular tool. Shox2+/+ and Shox2−/− ESC clones were isolated and differentiated according to five different protocols in order to evaluate the most efficient enrichment of SAN-like cells. Expression analysis of cell subtype-specific marker genes revealed most efficient enrichment after CD166-based cell sorting. Comparative cardiac expression profiles of Shox2+/+ and Shox2−/− ESCs were examined by nCounter technology. Among other genes, we identified Nppb as a novel putative Shox2 target during differentiation in ESCs. Differential expression of Nppb could be confirmed in heart tissue of Shox2−/− embryos. Taken together, we established an ESC-based cardiac differentiation model and successfully purified Shox2+/+ and Shox2−/− SAN-like cells. This now provides an excellent basis for the investigation of molecular mechanisms under physiological and pathophysiological conditions for evaluating novel therapeutic approaches

Modeling Stem Cell Induction Processes

Technology for converting human cells to pluripotent stem cell using induction processes has the potential to revolutionize regenerative medicine. However, the production of these so called iPS cells is still quite inefficient and may be dominated by stochastic effects. In this work we build mass-action models of the core regulatory elements controlling stem cell induction and maintenance. The models include not only the network of transcription factors NANOG, OCT4, SOX2, but also important epigenetic regulatory features of DNA methylation and histone modification. We show that the network topology reported in the literature is consistent with the observed experimental behavior of bistability and inducibility. Based on simulations of stem cell generation protocols, and in particular focusing on changes in epigenetic cellular states, we show that cooperative and independent reaction mechanisms have experimentally identifiable differences in the dynamics of reprogramming, and we analyze such differences and their biological basis. It had been argued that stochastic and elite models of stem cell generation represent distinct fundamental mechanisms. Work presented here suggests an alternative possibility that they represent differences in the amount of information we have about the distribution of cellular states before and during reprogramming protocols. We show further that unpredictability and variation in reprogramming decreases as the cell progresses along the induction process, and that identifiable groups of cells with elite-seeming behavior can come about by a stochastic process. Finally we show how different mechanisms and kinetic properties impact the prospects of improving the efficiency of iPS cell generation protocols.Fundação para a Ciência e a Tecnologia (BD 42942)MIT-Portugal ProgramNational Institutes of Health (U.S.) (CA112967)Singapore–MIT Alliance for Research and TechnologyIntel Corporatio

Community recommendations on terminology and procedures used in flooding and low oxygen stress research

Apart from playing a key role in important biochemical reactions, molecular oxygen (O2) and its by-products also have crucial signaling roles in shaping plant developmental programs and environmental responses. Even under normal conditions, sharp O2 gradients can occur within the plant when cellular O2 demand exceeds supply, especially in dense organs such as tubers, seeds and fruits. Spatial and temporal variations in O2 concentrations are important cues for plants to modulate development (van Dongen & Licausi, 2015; Considine et al., 2016). Environmental conditions can also expand the low O2 regions within the plant. For example, excessive rainfall can lead to partial or complete plant submergence resulting in O2 deficiency in the root or the entire plant (Voesenek & Bailey-Serres, 2015). Climate change-associated increases in precipitation events have made flooding a major abiotic stress threatening crop production and food sustainability. This increased flooding and associated crop losses highlight the urgency of understanding plant flooding responses and tolerance mechanisms. Timely manifestation of physiological and morphological changes triggering developmental adjustments or flooding survival strategies requires accurate sensing of O2 levels. Despite progress in understanding how plants sense and respond to changes in intracellular O2 concentrations (van Dongen & Licausi, 2015), several questions remain unanswered due to a lack of high resolution tools to accurately and noninvasively monitor (sub)cellular O2 concentrations. In the absence of such tools, it is therefore critical for researchers in the field to be aware of how experimental conditions can influence plant O2 levels, and thus on the importance of accurately reporting specific experimental details. This also requires a consensus on the definition of frequently used terms. At the 15th New Phytologist Workshop on Flooding stress (Voesenek et al., 2016), community members discussed and agreed on unified nomenclature and standard norms for low O2 and flooding stress research. This consensus on terminology and experimental guidelines is presented here. We expect that these norms will facilitate more effective interpretation, comparison and reproducibility of research in this field. We also highlight the current challenges in noninvasively monitoring and measuring O2 concentrations in plant cells, outlining the technologies currently available, their strengths and drawbacks, and their suitability for use in flooding and low O2 research

Metabolic Profiling of a Mapping Population Exposes New Insights in the Regulation of Seed Metabolism and Seed, Fruit, and Plant Relations

To investigate the regulation of seed metabolism and to estimate the degree of metabolic natural variability, metabolite profiling and network analysis were applied to a collection of 76 different homozygous tomato introgression lines (ILs) grown in the field in two consecutive harvest seasons. Factorial ANOVA confirmed the presence of 30 metabolite quantitative trait loci (mQTL). Amino acid contents displayed a high degree of variability across the population, with similar patterns across the two seasons, while sugars exhibited significant seasonal fluctuations. Upon integration of data for tomato pericarp metabolite profiling, factorial ANOVA identified the main factor for metabolic polymorphism to be the genotypic background rather than the environment or the tissue. Analysis of the coefficient of variance indicated greater phenotypic plasticity in the ILs than in the M82 tomato cultivar. Broad-sense estimate of heritability suggested that the mode of inheritance of metabolite traits in the seed differed from that in the fruit. Correlation-based metabolic network analysis comparing metabolite data for the seed with that for the pericarp showed that the seed network displayed tighter interdependence of metabolic processes than the fruit. Amino acids in the seed metabolic network were shown to play a central hub-like role in the topology of the network, maintaining high interactions with other metabolite categories, i.e., sugars and organic acids. Network analysis identified six exceptionally highly co-regulated amino acids, Gly, Ser, Thr, Ile, Val, and Pro. The strong interdependence of this group was confirmed by the mQTL mapping. Taken together these results (i) reflect the extensive redundancy of the regulation underlying seed metabolism, (ii) demonstrate the tight co-ordination of seed metabolism with respect to fruit metabolism, and (iii) emphasize the centrality of the amino acid module in the seed metabolic network. Finally, the study highlights the added value of integrating metabolic network analysis with mQTL mapping

The FunGenES Database: A Genomics Resource for Mouse Embryonic Stem Cell Differentiation

Embryonic stem (ES) cells have high self-renewal capacity and the potential to differentiate into a large variety of cell types. To investigate gene networks operating in pluripotent ES cells and their derivatives, the “Functional Genomics in Embryonic Stem Cells” consortium (FunGenES) has analyzed the transcriptome of mouse ES cells in eleven diverse settings representing sixty-seven experimental conditions. To better illustrate gene expression profiles in mouse ES cells, we have organized the results in an interactive database with a number of features and tools. Specifically, we have generated clusters of transcripts that behave the same way under the entire spectrum of the sixty-seven experimental conditions; we have assembled genes in groups according to their time of expression during successive days of ES cell differentiation; we have included expression profiles of specific gene classes such as transcription regulatory factors and Expressed Sequence Tags; transcripts have been arranged in “Expression Waves” and juxtaposed to genes with opposite or complementary expression patterns; we have designed search engines to display the expression profile of any transcript during ES cell differentiation; gene expression data have been organized in animated graphs of KEGG signaling and metabolic pathways; and finally, we have incorporated advanced functional annotations for individual genes or gene clusters of interest and links to microarray and genomic resources. The FunGenES database provides a comprehensive resource for studies into the biology of ES cells

Die Bestandsaufnahme als Kernelement bei der Weiterentwicklung des Mannheimer Wissenschaftscurriculums im Modellstudiengang Medizin

Introduction: The German Council of Science and Humanities as well as a number of medical professional associations support the strengthening of scientific competences by developing longitudinal curricula for teaching scientific competences in the undergraduate medical education. The National Competence Based Catalogue of Learning Objectives for Undergraduate Medical Education (NKLM) has also defined medical scientific skills as learning objectives in addition to the role of the scholar. The development of the Mannheim science curriculum started with a systematic inventory of the teaching of scientific competences in the Mannheim Reformed Curriculum of Medicine (MaReCuM). Methods: The inventory is based on the analysis of module profiles, teaching materials, surveys among experts, and verbatims from memory. Furthermore, science learning objectives were defined and prioritized, thus enabling the contents of the various courses to be assigned to the top three learning objectives. Results: The learning objectives systematic collection of information regarding the current state of research, critical assessment of scientific information and data sources, as well as presentation and discussion of the results of scientific studies are facilitated by various teaching courses from the first to the fifth year of undergraduate training. The review reveals a longitudinal science curriculum that has emerged implicitly. Future efforts must aim at eliminating redundancies and closing gaps; in addition, courses must be more closely aligned with each other, regarding both their contents and their timing, by means of a central coordination unit. Conclusion: The teaching of scientific thinking and working is a central component in the MaReCuM. The inventory and prioritization of science learning objectives form the basis for a structured ongoing development of the curriculum. An essential aspect here is the establishment of a central project team responsible for the planning, coordination, and review of these measures.Zielsetzung: Die Stärkung wissenschaftlicher Kompetenzen, u.a. durch die Entwicklung von longitudinalen Curricula zur Vermittlung von wissenschaftlichen Kompetenzen im Medizinstudium, wird vom Wissenschaftsrat und von verschiedenen Fachgesellschaften gefordert. Im Nationalen Kompetenzbasierten Lernzielkatalog Medizin (NKLM) wurden, neben dem Gelehrten, medizinisch-wissenschaftliche Fertigkeiten als Lernziele definiert. Auf dem Weg zum Mannheimer Wissenschaftscurriculum wurde zunächst das Ziel einer systematischen Bestandsaufnahme der Lehre wissenschaftlicher Kompetenzen im MaReCuM (Mannheimer Reformiertes Curriculum für Medizin) verfolgt. Methodik: Die Bestandsaufnahme basierte auf der Analyse von Modulsteckbriefen, Lehrmaterialien, Expertenbefragungen und Gedächtnisprotokollen. Weiterhin wurden wissenschaftsorientierte Lernziele definiert und priorisiert, so dass die Inhalte der verschiedenen Lehrveranstaltungen den drei am höchsten priorisierten Lernzielen zugeordnet werden konnten. Ergebnisse: Die Lernziele der systematischen Gewinnung von Informationen zum Stand der Forschung, kritischen Bewertung von wissenschaftlichen Informationen und Quellen, der Präsentation und Diskussion von Ergebnissen wissenschaftlicher Untersuchungen werden vom 1. bis 5. Studienjahr in verschiedenen Lehrveranstaltungen vermittelt. Es lässt sich ein longitudinales Wissenschaftscurriculum feststellen, welches implizit entstanden ist. In Zukunft müssen Redundanzen beseitigt und Lücken geschlossen sowie die Veranstaltungen inhaltlich und zeitlich mit Hilfe einer zentralen Koordination abgestimmt werden. Schlussfolgerung: Die Lehre des wissenschaftlichen Denkens und Arbeitens ist wesentlicher Bestandteil im MaReCuM. Die Bestandsaufnahme und die Priorisierung wissenschaftsorientierter Lernziele stellen die Basis für eine strukturierte Weiterentwicklung des Curriculums dar. Essentiell ist, dass eine zentrale Steuerungsgruppe diese Maßnahmen plant, koordiniert und überprüft