Oenothera, a unique model to study the role of plastids in speciation

The subject of this thesis was to develop molecular approaches appropriate to investigate speciation processes. The genus Oenothera was chosen for study, since it offers the unique possibility to exchange plastids, individual or more chromosomes and/or even entire haploid genomes (so-called Renner complexes) between species. In addition, a rich stock of information in taxonomy, cytogenetics and formal genetics is available, collected for more than a century of research. Interspecific exchange of plastids, nuclear genomes or chromosomes often leads to mis-development of the resulting hybrids. These inviable hybrids form hybridization barriers responsible for speciation. In the case of plastid and nuclear genome exchange, hybrid bleaching is frequently observed, which results from plastome-genome incompatibility (PGI) due to compartmental co-evolution. Traditional work on Oenothera was almost exclusively restricted to classical genetic and cytogenetic approaches. Subsection Oenothera, the best studied of the five subsections in the section Oenothera, was used in this work. It is comprised of three basic nuclear genomes, A, B and C, which occur in homozygous (AA, BB, CC) or stable heterozygous (AB, AC, BC) combination. In nature, the nuclear genomes are associated with five basic, genetically discernible plastid types (I - V) in distinct combinations. The following results were obtained: (i) Biochemistry with Oenothera is not trivial due to exceedingly high amounts of mucilage and tannins which adversely interfere with the isolation of macromolecules and enzymatic reactions. A basic biochemistry for the material was therefore developed initially, notably to obtain appropriate subcellular fractions, restricable, amplifyable and clonable DNA, RNA, supramolecular protein assemblies and proteins of appropriate purity. (ii) Evaluation of the PGI literature clearly indicates that PGI can form hybridization barriers according to the Dobzhansky-Muller gene pair model of speciation, even if the genes reside in different cellular compartments. (iii) Oenothera PGIs could be classified into four genetically distinct categories, which influence hybridization barriers in different ways. (iv) Co-dominant marker systems (SSLP and CAPS) were generated for both, nuclear genome and plastome. Their potential was successfully evaluated with crossing programs designed to exchange plastomes, genomes, or individual chromosomes between species. (v) The plastome markers allowed to genotype 41 subplastomes to judge inter- and intraplastome diversity and displayed molecular loci linked to the genetic behaviour of basic plastome types I - V. (vi) A single, highly polymorphic marker (M40) was sufficient to genotype 29 different Renner complexes of the basic genome types A, B and C. (vii) Markers specific for all seven Oenothera chromosomes were selected. Combined with the genetics of a partial permanent translocation heterozygote (ring of 12 chromosomes plus 1 bivalent, which behave as two distinct linkage groups) they allowed the assignment of molecular linkage group 7 to chromosome 9•8 of the classical Oenothera map. Material for the assignment of the remaining chromosomes and their arms was produced or selected so that both map types can now be fully integrated. (viii) In parallel to work on the nuclear genome, the sequences of the five basic Oenothera plastomes were completed (in cooperation). Elaborated in this thesis, due to its limited coding potential, conserved nature, and substantial knowledge about photosynthesis, plastid chromosomes provide relatively easy access to “speciation genes” and selection pressures causing speciation. (ix) Phylogenetic analysis of the sequences provided a plastome pedigree, and also an idea about the age of the subsection, i.e. back to the middle of Pleistocene, approximately 1 mya ago. This contributed to solve a long lasting question in the Oenothera literature. (x) Application of appropriate algorithms uncovered for the first time that plastomes are subject to natural selection and hence contribute to speciation. This was questioned repeatedly. (xi) A novel weighting strategy, combining classical genetic data on plastome-genome compatibility/incompatibility with molecular data and bioinformatic approaches, was applied to deduce potential plastid determinants for PGI. (xii) In a case study it could be shown that a single plastid locus contributes substantially to PGI in the interspecific hybrid AB-I, which was found to be defective in photosystem II. A plastome I-specific deletion in the bidirectional promoter region between psbB and clpP was found to be responsible for the phenotype observed. The finding is consistent with reduced levels of psbB mRNA and its product CP47 chlorophyll a apoprotein of photosystem II, with spectroscopic data and phenotype. (xiii) Available data indicate that interspecific plastome-genome hybrids represent some sort of “network mutants”. This would imply that speciation is predominantly a regulatory phenomenon. In the studied cases PGIs are is involved in the fine-tuning of regulation of photosynthesis, rather than in an adaptation of its structural components. This is considered as a major finding of this thesis

Variable amounts of DNA related to the size of chloroplasts III. Biochemical determinations of DNA amounts per organelle

Plastid genomes (plastomes) are part of the integrated compartmentalised genetic system of photoautotrophic eukaryotes. They are highly redundant and generally dispersed in several regions (nucleoids) within organelles. DNA quantities and number of DNA-containing regions per plastid vary and are developmentally regulated in a way not yet understood. Reliable quantitative data describing these patterns are scarce. We present a protocol to isolate fractions of pure plastids with varying average sizes from leaflets (≤1 mm) and leaves of different developmental stages continuously up to maturity (25 cm) from Beta vulgaris L. (sugar beet) to determine DNA amounts per organelle. The approach is based on plastid purification from homogenates of moderately fixed tissue by differential and isopycnic gradient centrifugations and on application of two different DNA specific colorimetric reactions after removing potentially interfering compounds. The sensitive fluorochrome DAPI (4′,6-diamidino-2-phenylindole) was used to estimate numbers and emission intensity of nucleoids per plastid. The amounts determined ranged from 0.15 to 4.9 × 10−2 pg DNA for plastids of 1→8 μm average diameter, corresponding from approximately a dozen to 330 genome equivalents per organelle and on average four to seven copies per nucleoid. The ratio of plastid/nuclear DNA changed continuously during leaf development from as little as 0.4% to about 20% in fully developed leaves. On the other hand, mesophyll cells of mature leaves differing in ploidy (di-, tri- and tetraploid) appeared to maintain a relatively constant nuclear genome/plastome ratio, equivalent to about 1,700 copies per C-value

Tribological performance and microstructural evolution of α-brass alloys as a function of zinc concentration

Tailoring a material’s properties for low friction and little wear in a strategic fashion is a long-standing goal of materials tribology. Plastic deformation plays a major role when metals are employed in a sliding contact; therefore, the effects of stacking fault energy and mode of dislocation glide need to be elucidated. Here, we investigated how a decrease in the stacking fault energy affects friction, wear, and the ensuing sub-surface microstructure evolution. Brass samples with increasing zinc concentrations of 5, 15, and 36 wt% were tested in non-lubricated sphere-on-plate contacts with a reciprocating linear tribometer against Si$_{3}$N$_{4}$ spheres. Increasing the sliding distance from 0.5 (single trace) to 5,000 reciprocating cycles covered different stages in the lifetime of a sliding contact. Comparing the results among the three alloys revealed a profound effect of the zinc concentration on the tribological behavior. CuZn15 and CuZn36 showed similar friction and wear results, whereas CuZn5 had a roughly 60% higher friction coefficient (COF) than the other two alloys. CuZn15 and CuZn36 had a much smaller wear rate than CuZn5. Wavy dislocation motion in CuZn5 and CuZn15 allowed for dislocation self-organization into a horizontal line about 150 nm beneath the contact after a single trace of the sphere. This feature was absent in CuZn36 where owing to planar dislocation slip band-like features under a 45° angle to the surface were identified. These results hold the promise to help guide the future development of alloys tailored for specific tribological applications

Threshold Resonant Structure of the 232Th Neutron-Induced Fission Cross Section

The structures observed in the sub-threshold neutron-induced fission of ^{232}Th were investigated employing a recent developed model. Theoretical single-particle excitations of a phenomenological two-humped barrier are determined by solving a system of coupled differential equations for the motion along the optimal fission path. A rather good agreement with experimental data was obtained using a small number of independent parameters. It is predicted that the structure at 1.4 and 1.6 MeV is mainly dominated by spin 3/2 partial cross-section with small admixture of spin 1/2, while the structure at 1.7 MeV is given by a large partial cross section of spin 5/2.Comment: 17 pages 11 figure

Article 6 Piloting: State of Play and Stakeholder Experiences

This report is the 3rd edition of a series started in 2019 and provides an updated overview of all aspects related to the piloting and operationalization of Article 6 of the Paris Agreement. Despite the continued uncertainty regarding the finalization of the Article 6 rules, practical Article 6 piloting is continuing apace and the landscape of Article 6 piloting initiatives evolves. Testing how Article 6 cooperation could work in practice in order to inform negotiations as well as getting early access to sources of emissions credits is seen as important to fulfill national mitigation commitments. As a framework for the analysis in our study, we apply a ‘concentric ring’ model that clearly differentiates between piloting activities that aim at generating Internationally Transferred Mitigation Outcomes (ITMOs) or adaptation benefits (ABs), initiatives that will eventually be governed by Article 6 rules and the enabling environment, which is essential to drive piloting efforts forward. In an additional analytical step, we classify piloting activities in the inner circle according to three different phases: the preparatory phase, the pilot phase and the full implementation phase. Moreover, we summarise current stakeholder experiences with Article 6 piloting and provide an overview of our insights from broad and deep stakeholder consultations, including the views of buyer countries, host countries and project developers

Litauische Musik: Idee und Geschichte einer musikalischen Nationalbewegung in ihrem europäischen Kontext

Dass Europa als Gemeinschaft eine gemeinsame Kulturbasis besitzt, ist ein wichtiger Gedanke für die Europäische Union. In Deutschland ist dieser Gedanke sehr populär, aber über die Kulturen insbesondere östlicher europäischer Staaten weiÿ man im Allgemeinen relativ wenig. Seit dem 19. Jahrhundert haben sich die Nationalkulturen in Europa gegeneinander abgegrenzt, jede Nation begann sich als exklusiv zu verstehen und einen eigenen nationalen Wertekanon zu bilden. Hier vollzog sich ein Circulus vitiosus, in dem die Menschen ablehnen, was sie nicht kennen, und nicht kennen, was sie ablehnen. Wenn der politische Wille zu einer Stärkung des europäischen Gedankens vorhanden ist, so kann die Wissenschaft dazu durch Analyse der Situation und Aufarbeitung von historischenMaterialien einen wichtigen Beitrag leisten. Die Aufgabe ist riesig, aber jeder kleine Schritt zählt. Die Musik wird in diesem Zusammenhang meist unterschätzt, zu mächtig ist die leitende Vorstellung, sie sei von Natur aus völkerverbindend. Dass sie in kunstreligiöser Form vielfach der Unterdrückung und Abgrenzung von Staaten gedient hat, die sich als Kulturnationen verstanden, wird meist übersehen. Dass die Ablehnung und das Ignorieren von Nationalkulturen ähnliche Auswirkungen haben können, sollte nachdenklich stimmen. In jüngerer Zeit den sich dank der Initiative der litauischen Musikwissenschaft eine ganze Reihe informativer Beiträge über litauische Musik in englischer Sprache. Die Möglichkeiten, sich in deutscher Sprache über litauische Musik zu informieren, sind bisher gering. Neben einem älteren Buch existieren Überblicksartikel in Lexika3 und einige Aufsätze in Sammelbänden, insbesondere in den Mitteilungsheften und Konferenzberichten der Arbeitsgemeinschaft für die Musikgeschichte in Mittel- und Osteuropa. In ihrem Rahmen wurde vom 18. bis 20. Mai 2008 am Institut für Musikwissenschaft der Universität Leipzig eine Konferenz veranstaltet, aus der das vorliegende Buch hervorgegangen ist. Es versammelt nicht nur die Konferenzbeiträge, sondern wurde zusätzlich um einige wesentliche Aufsätze ergänzt. Die wichtigsten Repräsentanten der litauischen Musikwissenschaft mit ihren speziellen Forschungsgebieten sind vertreten und werden durch grenzübergreifende Beiträge von Kollegen aus anderen europäischen Ländern ergänzt, um die Geschichte der litauischen musikalischen Nationalbewegung in ihrem europäischen Kontext von ihren Vorläufern und Anfängen bis heute nach neuestem Erkenntnisstand in deutscher Sprache vorzustellen

Управління ресурсним потенціалом вугільних шахт

Викладено методичні підходи з удосконалення управління ресурсним потенціалом вугільних шахт на основі використання двокритерійної моделі градієнтного регулювання їх потужності. Запропоновано механізм оцінки параметрів стану шахт у процесі зміни їх потужності, який полягає у визначенні впливу градієнтної зміни ліміту наявного ресурсного потенціалу на рівень інвестиційної привабливості підприємства, що науково обґрунтовує їх віднесення до певних приватизаційних груп. Удосконалено процесний підхід до управління ресурсним потенціалом вугільних шахт в умовах невизначеності. Запропоновано організаційно-економічний механізм управління ресурсним потенціалом вугільних шахт в умовах нестійкого попиту на вугілля. Розрахована на фахівців з управління підприємствами вугільної промисловості та інженерно-технічних працівників, а також учених, викладачів вищих навчальних закладів