Evolutionary conservation of epigenetic control of plant sexual reproduction

During the course of evolution, land plants evolved a peculiar haplodiplontic life cycle in which both the haploid gametophyte and the diploid sporophyte are multicellular. Within the life cycle, the phase transition between these two stages is called the alternation of generations. However, within land plants the dominant generation varies. Following the alternation of generations on molecular level is difficult to analyse in flowering plants due to their diploid-dominant generation and their highly reduced gametophytic generation. Bryophytes, in contrast, are haploid-dominant plants, have more easily tractable (morphologically larger) generations and share with flowering plants the fundamental regulatory networks for switching between vegetative and reproductive growth. This switch is most often regulated by transcription associated proteins (TAPs). Combining an orthology detection tool (proteinortho), protein-family categorization (TAPscan), literature search and phylogenetic inference a set of candidate genes, representing single copy TAPs potentially involved in embryo development, was identified. In bryophytes the knowledge of sexual reproduction and evolution of plant sexual reproduction is limited as compared to seed plants. Even though, bryophyte plants defective in gametangiogenesis or embryo/sporophyte development often can be grown as gametophytic tissue and vegetatively propagated contrary to flowering plants. Two master regulators (swi3a/b, hag1) were identified. It could be shown that they are indeed crucial for sexual reproduction and thus the knowledge about the regulation of sexual reproduction in bryophytes could be amended. Deletion of the respective genes led to a loss of sporophyte development due to an impairment in the male germ line in the latest steps of spermatozoid ripening on the part of swi3a/b, and an impairment in the male and female germ lines (disturbed ripening) on the part of hag1. Hag1 is a highly conserved gene throughout all eukaryotic kingdoms, which was proven by phylogenetic analyses and underlined by mutants impaired in the male germ line in moss as well as flowering plants. In contrast, the SWI3 family diversified during land plant evolution (one SWI3 gene in algae, four SWI3 genes in Arabidopsis thaliana). That was underlined by the phenotypical analyses in Physcomitrium patens and A. thaliana, which showed a shift from a male exclusive role of swi3a/b in P. patens towards an involvement in male and female gametogenesis as well as embryogenesis in A. thaliana. These findings underline the hypothesis that on one hand TAPs can be highly conserved and can serve as single copy phylogenetic markers, whereas on the other hand TAP families expanded with plant complexity as drivers for morphogenic evolution. All in all, TAPs are important developmental regulators, that can be used for analysing the plants’ potential to adapt to new conditions

Microstructural development in Al-Si powder during rapid solidification

Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to further exploit the potential of rapid solidification processing. Aluminum-silicon, one alloy of significant industrial importance, was chosen as a model for simple eutectic systems displaying an unfaceted/faceted interface and skewed coupled eutectic growth zone. Al-Si powder produced by high pressure gas atomization was studied to determine the relationship between microstructure and alloy composition as a function of powder size and atomization gas. Critical experimental measurements of hypereutectic (Si-rich) compositions were used to determine undercooling and interface velocity, based on the theoretical models which are available. A revised microstructural map is proposed which allows the prediction of particle morphology based on temperature and composition

Flow effects on the dendritic microstructure of AlSi-base alloys

Fluid flow changes heat and mass transport during solidification, thereby affecting the evolution of the microstructure. In order to quantify effects of convection, it is important that fluid flow can be modified experimentally. We performed directional solidification experiments with binary AlSi alloys of different compositions, using a microgravity environment for diffusive solidification and adding rotating magnetic fields to generate flow. Flow velocities up to 10 mm/s and various solidification velocities were realized while maintaining a constant temperature gradient at the solid-liquid interface. The microstructure observed in samples processed on earth and in space is characterized by primary and secondary dendrite arm spacing and the fractal dimension of the dendrites. It is found that fluid flow usually accelerates growth and coarsening of the dendritic structures and leads to new kinetic laws. The branching of dendritic networks, however, is hardly affected by flow

Microstructural Development in Al-Si Powder During Rapid Solidification

Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to further exploit the potential of rapid solidification processing. Aluminum-silicon, an alloy of significant industrial importance, was chosen as a model for simple eutectic systems displaying an unfaceted/faceted interface and skewed coupled eutectic growth zone, Al-Si powder produced by high pressure gas atomization was studied to determine the relationship between microstructure and alloy composition as a function of powder size and atomization gas. Critical experimental measurements of hypereutectic (Si-rich) compositions were used to determine undercooling and interface velocity, based on the theoretical models which are available. Solidification conditions were analyzed as a function of particle diameter and distance from nucleation site. A revised microstructural map is proposed which allows the prediction of particle morphology based on temperature and composition. It is hoped that this work, by providing enhanced understanding of the processes which govern the development of the solidification morphology of gas atomized powder, will eventually allow for better control of processing conditions so that particle microstructures can be optimized for specific applications

Furchtlose Dominanz und Führungserfolg : eine empirische Prüfung von Lykkens Sozialisationshypothese

Das Persönlichkeitsmerkmal furchtlose Dominanz umfasst sozial dominantes, stressresistentes sowie furchtloses Verhalten und stellt einen der beiden Hauptfaktoren der Psychopathie dar. Nach Lykken (1995) führen diese Eigenschaften bei niedriger kognitiver Intelligenz und geringer gesellschaftlicher Sozialisation zu antisozialem Verhalten. Bei hoher kognitiver Intelligenz und hierdurch gefördertem Sozialisationserfolg sollen diese Eigenschaften dagegen mit besonderen gesellschaftlich anerkannten Leistungen einhergehen. In bisherigen Studien hat sich das Bildungslevel als Indikator intelligenzbasierter Sozialisation bewährt und es fanden sich erste unterstützende empirische Befunde für Lykkens Annahme hinsichtlich objektiver und subjektiver beruflicher Erfolgskriterien. Ein anerkanntes Kriterium besonderen gesellschaftlichen Erfolgs, welches aufgrund der umfassenden Einflussmöglichkeiten für furchtlos dominante Personen insbesondere attraktiv ist, stellen Führungspositionen dar. In der vorliegenden Studie wurde daher erstmalig Lykkens Sozialisationshypothese im Führungskontext getestet. Dafür wurde das Zusammenspiel von furchtloser Dominanz und dem Bildungslevel bei Führungskräften geprüft und die Wirkmechanismen untersucht, über welche die furchtlose Dominanz abhängig vom Sozialisationshintergrund zu mehr oder weniger Führungserfolg führt. Diese Untersuchung erfolgte in einem branchenübergreifenden, querschnittlichen Multisource-Online-Feldstudiendesign mit 239 Führungskräften, deren direkten Vorgesetzten sowie Mitarbeitenden. Die Hypothesen wurden mittels moderierter Mediationsanalysen mit unterschiedlichen Kriterien der Führungseffektivität getestet. In den Ergebnissen zeigte sich, dass die hoch furchtlos dominanten Führungskräfte mit hohem Bildungslevel als politisch geschickter eingeschätzt wurden, was mit besseren Beurteilungen ihrer Arbeitsleistung, ihres transformationalen Führungsverhaltens sowie (vermittelt über das transformationale Führungsverhalten) der Gruppenleistung ihres geführten Teams einherging. War das Bildungslevel gering, waren diese Zusammenhänge in der Tendenz negativ. Insgesamt unterstützen die Ergebnisse damit Lykkens Annahme, dass die furchtlose Dominanz bei erfolgreicher Sozialisation mit beruflichem Erfolg einhergeht, bei weniger erfolgreichem Sozialisationshintergrund jedoch einen potenziellen Nachteil darstellen kann. Auf Basis dieser Ergebnisse wird die furchtlose Dominanz in der vorliegenden Arbeit als Ressource für die Führungsforschung und -praxis eingeführt. Ebenso werden abschließend Stärken und Limitationen dieser Ergebnisse durch das verwendete Studiendesign diskutiert und eingeordnet sowie ein Ausblick auf weitere Forschungsperspektiven gegeben

Die Biosynthese des Vitamin B₆ und des Gingotoxins als Beispiel einer Konvergenz : Klonierung und Expression eines sor-homologen Gens aus Ginkgo biloba L., Ginkgoaceae

Mit den Ergebnissen zur Biosynthese des Vitamin B6 in verschiedenen Organismen haben sich in den letzten Jahren zahlreiche neue Aspekte eröffnet. Ging man zuvor davon aus, alle zur Biosynthese befähigten Organismen synthetisierten diese Stoffe auf die gleiche Weise, wissen wir heute, daß es zumindest zwei unterschiedliche Bio-synthesewege in der Natur gibt. Diese sollten sich sowohl in ihren genetischen Grund-lagen als auch in ihrer Biochemie grundsätzlich unterscheiden. Zahlreiche Argumente sprechen dafür, daß Ginkgo biloba zu der Gruppe von Or-ganismen zählt, die die Biosynthese auf eine andere als der bisher aus dem Entero-bakterium Escherichia coli bekannten Weise durchführt. Zur Aufklärung dieses neuen Syntheseweges fehlen noch zahlreiche Informationen: Mit Sicherheit kann zunächst die Beteiligung des sor(pdx1)-Genes bestätigt werden; die Funktion des Genproduktes ist noch unklar. Im Rahmen dieser Arbeit ist es gelungen, ein Gen aus der Pflanze Ginkgo biloba -Ginkgoaceae - zu klonieren, dessen Sequenz große Homologie zu den bekannten sor/pdx1-Genen aufweist. Es konnte sowohl in einem prokaryontischen als auch eu-karyontischen Wirt exprimiert werden; es gelang, das aus der prokaryontischen Ex-pression erhaltene Protein, teilweise zu reinigen. Es steht für den Einsatz im zellfreien System nach Fiehe (1999) zur Verfügung. In verschiedenen Organismen wird mit dem sor-Gen das sno-Gen koreguliert; die Annahme einer Amidotransferase-Aktivität für dessen Genprodukt bleibt zur Zeit noch hypothetisch und bedarf weiterer Untersuchungen. Ferner ist noch nicht abschließend geklärt, ob weitere Gene für Enzyme dieses Stoffwechselweges kodieren. Die Biochemie dieses alternativen Vitamin B6-Syntheseweges ist weitgehend uner-forscht. Zwar haben Spenser und Mitarbeiter Hinweise darauf, daß eine Pentose zur Bildung des Pyridinringes beträgt, doch sind noch weitere Kohlenstoffeinheiten zum Aufbau des Grundgerüstes nötig. Ebenso sind die beteiligten Enzyme, sofern sie be-kannt sind, uncharakterisiert

Evolution of the Symbiosis-Specific GRAS Regulatory Network in Bryophytes

Arbuscular mycorrhiza is one of the most common plant symbiotic interactions observed today. Due to their nearly ubiquitous occurrence and their beneficial impact on both partners it was suggested that this mutualistic interaction was crucial for plants to colonize the terrestrial habitat approximately 500 Ma ago. On the plant side the association is established via the common symbiotic pathway (CSP). This pathway allows the recognition of the fungal symbiotic partner, subsequent signaling to the nucleus, and initiation of the symbiotic program with respect to specific gene expression and cellular re-organization. The downstream part of the CSP is a regulatory network that coordinates the transcription of genes necessary to establish the symbiosis, comprising multiple GRAS transcription factors (TFs). These regulate their own expression as an intricate transcriptional network. Deduced from non-host genome data the loss of genes encoding CSP components coincides with the loss of the interaction itself. Here, we analyzed bryophyte species with special emphasis on the moss Physcomitrella patens, supposed to be a non-host, for the composition of the GRAS regulatory network components. We show lineage specific losses and expansions of several of these factors in bryophytes, potentially coinciding with the proposed host/non-host status of the lineages. We evaluate losses and expansions and infer clade-specific evolution of GRAS TFs

A Virtual Community of Practice to Introduce Evidence-based Pedagogy in Chemical, Materials, and Biological Engineering Courses

This paper describes a model for a virtual community of practice (VCP) to support faculty efforts to adopt research-based instructional strategies in Chemical, Materials and Biological Engineering courses. The VCP was built on published recommendations for successful faculty development programs. The VCP program began with a 10 week virtual training period for five pairs of VCP leaders, during which they acquired the skills and knowledge needed to lead the faculty VCP. The faculty VCPs focused on one of five technical disciplines and were led by a pair of leaders having expertise in a specific technical focus area as well as in engineering pedagogy. Workshops were held using Internet conferencing software: the first 8 weekly workshops provided training in research-based pedagogy, and the second 8 biweekly workshops supported faculty efforts to implement chosen strategies in their courses. The participants were full-time faculty members with a range of teaching experience and pedagogical expertise, ranging from novice to expert. Improvement was measured via pre/post survey in the areas of familiarity and use of research-based pedagogy, as well as in perceived student motivation. The second part of the paper focuses on the translation of faculty participant experiences from the VCP into the classroom as they implemented a variety of instructional methods in their courses. We describe their approaches and preliminary results using different instructional methods such as flipping the classroom, using game-based pedagogy, promoting positive interdependence in cooperative-learning teams, peer instruction, small group discussion, Process Oriented Guided Inquiry Learning (POGIL), and using Bloom’s Taxonomy to structure a course

HAG1 and SWI3A/B control of male germ line development in P. patens suggests conservation of epigenetic reproductive control across land plants

Bryophytes as models to study the male germ line: loss-of-function mutants of epigenetic regulators HAG1 and SWI3a/b demonstrate conserved function in sexual reproduction

An integrative approach to more nuanced estimates of personality–job–performance relations

This is the final version. Available on open access from Wiley via the DOI in this recordData availability statement: The data that support the findings of this study are openly available on OSF at https://osf.io/ys72j/?view_only=f48aeaf9414d46fb81019186030afbdcRecent research has suggested that self- and other-ratings of personality may provide different information about personality, which can be captured in the trait–reputation–identity (TRI) model. Based on the TRI model, we investigate the link between personality and aligned job performance criteria on domain and aspect levels of the Big Five personality traits. In five samples (overall N = 571 triplets of target self-ratings and two coworker other-ratings), we investigated the relationships between the shared information on personality and shared information about job performance. We found that all personality domains showed substantial criterion validity in predicting the corresponding job-performance dimensions. Furthermore, we found stronger estimates for aspects of agreeableness and openness. We discuss theoretical and practical implications for target replacement and performance management