Plasma Transport in Saturn's Low‐Latitude Ionosphere: Cassini Data

An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union.In 2017 the Cassini Orbiter made the first in situ measurements of the upper atmosphere and ionosphere of Saturn. The Ion and Neutral Mass Spectrometer in its ion mode measured densities of light ion species (H+, H2+, H3+, and He+), and the Radio and Plasma Wave Science instrument measured electron densities. During proximal orbit 287 (denoted P287), Cassini reached down to an altitude of about 3,000 km above the 1 bar atmospheric pressure level. The topside ionosphere plasma densities measured for P287 were consistent with ionospheric measurements during other proximal orbits. Spacecraft potentials were measured by the Radio and Plasma Wave Science Langmuir probe and are typically about negative 0.3 V. Also, for this one orbit, Ion and Neutral Mass Spectrometer was operated in an instrument mode allowing the energies of incident H+ ions to be measured. H+ is the major ion species in the topside ionosphere. Ion flow speeds relative to Saturn's atmosphere were determined. In the southern hemisphere, including near closest approach, the measured ion speeds were close to zero relative to Saturn's corotating atmosphere, but for northern latitudes, southward ion flow of about 3 km/s was observed. One possible interpretation is that the ring shadowing of the southern hemisphere sets up an interhemispheric plasma pressure gradient driving this flow

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

Complete Plastome Sequences of Equisetum arvense and Isoetes flaccida: Implications for Phylogeny and Plastid Genome Evolution of Early Land Plant Lineages

Background Despite considerable progress in our understanding of land plant phylogeny, several nodes in the green tree of life remain poorly resolved. Furthermore, the bulk of currently available data come from only a subset of major land plant clades. Here we examine early land plant evolution using complete plastome sequences including two previously unexamined and phylogenetically critical lineages. To better understand the evolution of land plants and their plastomes, we examined aligned nucleotide sequences, indels, gene and nucleotide composition, inversions, and gene order at the boundaries of the inverted repeats. Results We present the plastome sequences of Equisetum arvense, a horsetail, and of Isoetes flaccida, a heterosporous lycophyte. Phylogenetic analysis of aligned nucleotides from 49 plastome genes from 43 taxa supported monophyly for the following clades: embryophytes (land plants), lycophytes, monilophytes (leptosporangiate ferns + Angiopteris evecta + Psilotum nudum + Equisetum arvense), and seed plants. Resolution among the four monilophyte lineages remained moderate, although nucleotide analyses suggested that P. nudum and E. arvense form a clade sister to A. evecta + leptosporangiate ferns. Results from phylogenetic analyses of nucleotides were consistent with the distribution of plastome gene rearrangements and with analysis of sequence gaps resulting from insertions and deletions (indels). We found one new indel and an inversion of a block of genes that unites the monilophytes. Conclusions Monophyly of monilophytes has been disputed on the basis of morphological and fossil evidence. In the context of a broad sampling of land plant data we find several new pieces of evidence for monilophyte monophyly. Results from this study demonstrate resolution among the four monilophytes lineages, albeit with moderate support; we posit a clade consisting of Equisetaceae and Psilotaceae that is sister to the true ferns, including Marattiaceae

Präferenz für Intuition und Deliberation – Messung und Konsequenzen von affekt- und kognitionsbasiertem Entscheiden

Personen unterscheiden sich darin, ob sie bevorzugt intuitiv oder reflektiv entscheiden (Epstein et al., 1996). Um diese individuellen Unterschiede zu erfassen, wurde ein neues Fragebogenmaß konstruiert, das die Präferenz für Intuition und Deliberation (PID, Betsch, 2004) auf zwei unabhängigen Skalen misst (Präferenz für Intuition und Präferenz für Deliberation). Intuition wird hier als ein rein affektiver Modus verstanden. Deliberation ist konzipiert als reflektiver, kognitionsbasierter Modus. In drei Studien wird die Konstruktion, Überprüfung der Zweidimensionalität und Validierung der Skala anhand von insgesamt über 2500 Versuchspersonen berichtet (Betsch, 2004). Präferenz für Intuition korreliert positiv mit schnellem Entscheiden, Extraversion und Verträglichkeit und ist unabhängig von der Fähigkeit zu logischem Denken. Präferenz für Deliberation korreliert mit Gewissenhaftigkeit, Perfektionismus, Bedürfnis nach Strukturiertheit und ist ebenfalls unabhängig von logischem Denken. Die Validität der Skala und die Implikationen für die Entscheidungsforschung werden in einer weiteren Studie überprüft, die die Krümmung der Nutzenfunktion mit der individuellen Präferenz für Intuition und Deliberation in Verbindung setzt (Schunk & Betsch, im Druck). Die Ergebnisse der Studie zeigen, dass die Entscheidungen intuitiver Menschen das Gefühl, das durch erlebtes Risiko evoziert wurde, integrieren, während dies bei deliberaten Personen nicht der Fall ist. Dies führt zu unterschiedlich gekrümmten Nutzenfunktionen. Neben den Haupteffekten der Strategiepräferenzen werden auch die Interaktion zwischen der individuell bevorzugten und der tatsächlich angewandten Strategie in fünf Studien untersucht (Betsch & Kunz, zur Veröffentlichung eingereicht). Die Ergebnisse der Studien zeigen, dass die Passung zwischen der bevorzugten und tatsächlich verwendeten Strategie (sogenannter decisional fit) den wahrgenommenen Wert des gewählten oder evaluierten Objektes erhöht und dass die Passung als Schutzschild dient gegenüber negativen Emotionen (z.B. Bedauern) nach Entscheidungen mit schlechtem Ausgang. Zusammenfassend umfasst diese Dissertation die Konstruktion und Validierung der Skala zur Erfassung der individuellen Präferenz für Intuition und Deliberation (PID; Betsch, 2004). Weiterhin untersucht sie die Konsequenzen von individuellen Unterschieden in affekt- vs. kognitionsbasiertem Entscheiden auf einen basalen Entscheidungsparameter (die Nutzenfunktion, Schunk & Betsch, im Druck). Außerdem zeigen weitere Studien die Konsequenzen einer Person x Situation Interaktion für zentrale Variablen der Entscheidungsliteratur auf (Wert, Bedauern; Betsch & Kunz, zur Veröffentlichung eingereicht)

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

Peer reviewe

Evolution and networks in ancient and widespread symbioses between Mucoromycotina and liverworts

Like the majority of land plants, liverworts regularly form intimate symbioses with arbuscular mycorrhizal fungi (Glomeromycotina). Recent phylogenetic and physiological studies report that they also form intimate symbioses with Mucoromycotina fungi and that some of these, like those involving Glomeromycotina, represent nutritional mutualisms. To compare these symbioses, we carried out a global analysis of Mucoromycotina fungi in liverworts and other plants using species delimitation, ancestral reconstruction, and network analyses. We found that Mucoromycotina are more common and diverse symbionts of liverworts than previously thought, globally distributed, ancestral, and often co-occur with Glomeromycotina within plants. However, our results also suggest that the associations formed by Mucoromycotina fungi are fundamentally different because, unlike Glomeromycotina, they may have evolved multiple times and their symbiotic networks are un-nested (i.e., not forming nested subsets of species). We infer that the global Mucoromycotina symbiosis is evolutionarily and ecologically distinctive

Complex chloroplast RNA metabolism: just debugging the genetic programme?

<p>Abstract</p> <p>Background</p> <p>The gene expression system of chloroplasts is far more complex than that of their cyanobacterial progenitor. This gain in complexity affects in particular RNA metabolism, specifically the transcription and maturation of RNA. Mature chloroplast RNA is generated by a plethora of nuclear-encoded proteins acquired or recruited during plant evolution, comprising additional RNA polymerases and sigma factors, and sequence-specific RNA maturation factors promoting RNA splicing, editing, end formation and translatability. Despite years of intensive research, we still lack a comprehensive explanation for this complexity.</p> <p>Results</p> <p>We inspected the available literature and genome databases for information on components of RNA metabolism in land plant chloroplasts. In particular, new inventions of chloroplast-specific mechanisms and the expansion of some gene/protein families detected in land plants lead us to suggest that the primary function of the additional nuclear-encoded components found in chloroplasts is the transgenomic suppression of point mutations, fixation of which occurred due to an enhanced genetic drift exhibited by chloroplast genomes. We further speculate that a fast evolution of transgenomic suppressors occurred after the water-to-land transition of plants.</p> <p>Conclusion</p> <p>Our inspections indicate that several chloroplast-specific mechanisms evolved in land plants to remedy point mutations that occurred after the water-to-land transition. Thus, the complexity of chloroplast gene expression evolved to guarantee the functionality of chloroplast genetic information and may not, with some exceptions, be involved in regulatory functions.</p