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In times of a growing world population and the associated demand for high crop yield, the understanding and improvement of plant reproduction is of central importance. One key step of plant reproduction is the development of the male gametophyte, which is better known as pollen. In addition, the development of pollen was shown to be very sensitive to abiotic stresses, such as heat, which can cause crop damage and yield loss. To obtain new insights in the development and heat stress response of pollen, a combined transcriptome and proteome analysis was performed for three pollen developmental stages of non- and heat-stressed tomato plants.
The analysis of the transcriptomes of non-stressed pollen developmental stages enabled the determination of mRNAs accumulated in certain developmental stages. The functional analysis of these mRNAs led to the identification of protein families and functional processes that are important at different times of pollen development. A subsequent comparison of the transcriptomes of non- and heat-stressed pollen revealed a core set of 49 mRNAs, which are upregulated in all three developmental stages. The encoded proteins include among other things different heat stress transcription factors and heat shock proteins, which are known key players of the plant heat stress response.
Furthermore, 793 potential miRNAs could be identified in the transcriptome of non- and heat-stressed pollen. Interestingly, 38 out of the 793 miRNAs have already been identified in plants. For more than half of these miRNAs potential target mRNAs were identified and the interactions between miRNAs and mRNAs linked to the development and heat stress response of pollen. In total, 207 developmentally relevant interactions could be determined, out of which 34 have an effect on transcriptional-networks. In addition, 24 of the interactions contribute the heat stress response of pollen, whereby this mainly affects post-meiotic pollen.
An initial correlation of the proteome and transcriptome of the developmental stages revealed that transcriptome analyses are not sufficient to draw exact conclusions about the state of the proteome. A closer look on the relationship of the transcriptome and proteome during pollen development revealed two translational modes that are active during the development of pollen. One mode leads to a direct translation of mRNAs, while the second mode leads a delayed translation at a later point in time. Regarding the delayed translation, it could be shown that this is likely due to a short-term storage of mRNAs in so-called EPPs. The comparison of the proteome and transcriptome response to heat stress revealed that the proteome reacts much stronger and that the reaction is mainly independent from the transcriptome. Finally, the comparison of the proteome of non- and heat-stressed pollen provided first indications for changes in the ribosome composition in response to heat stress, as 57 ribosomal proteins are differentially regulated in at least one developmental stage.
Improved risk stratification in prevention by use of a panel of selected circulating microRNAs
(2017)
Risk stratification is crucial in prevention. Circulating microRNAs have been proposed as biomarkers in cardiovascular disease. Here a miR panel consisting of miRs related to different cardiovascular pathophysiologies, was evaluated to predict outcome in the context of prevention. MiR-34a, miR-223, miR-378, miR-499 and miR-133 were determined from peripheral blood by qPCR and combined to a risk panel. As derivation cohort, 178 individuals of the DETECT study, and as validation cohort, 129 individuals of the SHIP study were used in a case-control approach. Overall mortality and cardiovascular events were outcome measures. The Framingham Risk Score(FRS) and the SCORE system were applied as risk classification systems. The identified miR panel was significantly associated with mortality given by a hazard ratio(HR) of 3.0 (95% (CI): 1.09–8.43; p = 0.034) and of 2.9 (95% CI: 1.32–6.33; p = 0.008) after adjusting for the FRS in the derivation cohort. In a validation cohort the miR-panel had a HR of 1.31 (95% CI: 1.03–1.66; p = 0.03) and of 1.29 (95% CI: 1.02–1.64; p = 0.03) in a FRS/SCORE adjusted-model. A FRS/SCORE risk model was significantly improved to predict mortality by the miR panel with continuous net reclassification index of 0.42/0.49 (p = 0.014/0.005). The present miR panel of 5 circulating miRs is able to improve risk stratification in prevention with respect to mortality beyond the FRS or SCORE.
Eurozentrismus heißt das Schlagwort, welches die Wissenschaft der Völkerrechtsgeschichte seit einigen Jahren – wieder einmal, muss man sagen, blickt man auf die ersten kritischen Stimmen in den 1960er-Jahren zurück – beschäftigt. Im Zentrum steht dabei die Kritik an der klassischen Historiographie des Völkerrechts und insbesondere der führenden Rolle, die dem sogenannten Westen bzw. Europa darin zugeschrieben wird. Nach der traditionellen Narration ist das moderne Völkerrecht das Ergebnis einer europäischen Fortschrittsgeschichte, die ihren Ausgangspunkt im europäischen Mittealter nahm und sich im Laufe des 19. Jahrhunderts zu einem universell gültigen internationalen Rechtssystem herausbildete. Nicht-europäische Staaten spielen in dieser linearen und eurozentrischen Entwicklungsgeschichte, wenn überhaupt, nur eine passive Rolle. Nicht als Akteure, sondern als Rezipienten werden sie im Laufe des 19. Jahrhunderts Teil dieser europäischen Meistererzählung. "[I]t was in fact Europe and not America, Asia, or Africa that dominated and, in so doing, unified the world, it is not our perspective but the historical record itself that can be called Eurocentric", heißt es 1984 bei Hedley Bull und Adam Watson. Trotz verschiedener kritischer Gegenerzählungen ist diese klassische Narration auch heute noch prägend für das Selbstverständnis der Wissenschaft der Völkerrechtsgeschichte. ...
Background: Elucidating the genomic basis of adaptation and speciation is a major challenge in natural systems with large quantities of environmental and phenotypic data, mostly because of the scarcity of genomic resources for non-model organisms. The Atlantic molly (Poecilia mexicana, Poeciliidae) is a small livebearing fish that has been extensively studied for evolutionary ecology research, particularly because this species has repeatedly colonized extreme environments in the form of caves and toxic hydrogen sulfide containing springs. In such extreme environments, populations show strong patterns of adaptive trait divergence and the emergence of reproductive isolation. Here, we used RNA-sequencing to assemble and annotate the first transcriptome of P. mexicana to facilitate ecological genomics studies in the future and aid the identification of genes underlying adaptation and speciation in the system.
Description: We provide the first annotated reference transcriptome of P. mexicana. Our transcriptome shows high congruence with other published fish transcriptomes, including that of the guppy, medaka, zebrafish, and stickleback. Transcriptome annotation uncovered the presence of candidate genes relevant in the study of adaptation to extreme environments. We describe general and oxidative stress response genes as well as genes involved in pathways induced by hypoxia or involved in sulfide metabolism. To facilitate future comparative analyses, we also conducted quantitative comparisons between P. mexicana from different river drainages. 106,524 single nucleotide polymorphisms were detected in our dataset, including potential markers that are putatively fixed across drainages. Furthermore, specimens from different drainages exhibited some consistent differences in gene regulation.
Conclusions: Our study provides a valuable genomic resource to study the molecular underpinnings of adaptation to extreme environments in replicated sulfide spring and cave environments. In addition, this study adds to the increasing number of genomic resources in the family Poeciliidae, which are widely used in comparative analyses of behavior, ecology, evolution, and medical genetics.
Die ursprünglich über zwei Meter hohe Inschrift von Paros, im Folgenden hier gemäß der gängigen Konvention als Marmor Parium bezeichnet, stellt einen faszinierenden Text dar, der in den Altertumswissenschaften jedoch kaum größere Beachtung erfährt. Umso erfreulicher ist es, dass sich Andrea Rotstein in einer monographischen Abhandlung eingehend damit beschäftigte und erstmals seit über 100 Jahren auch eine neue Edition mitsamt englischer Übersetzung vorlegte. ...
Containment problems belong to the classical problems of (convex) geometry. In the proper sense, a containment problem is the task to decide the set-theoretic inclusion of two given sets, which is hard from both the theoretical and the practical perspective. In a broader sense, this includes, e.g., radii or packing problems, which are even harder. For some classes of convex sets there has been strong interest in containment problems. This includes containment problems of polyhedra and balls, and containment of polyhedra, which have been studied in the late 20th century because of their inherent relevance in linear programming and combinatorics.
Since then, there has only been limited progress in understanding containment problems of that type. In recent years, containment problems for spectrahedra, which naturally generalize the class of polyhedra, have seen great interest. This interest is particularly driven by the intrinsic relevance of spectrahedra and their projections in polynomial optimization and convex algebraic geometry. Except for the treatment of special classes or situations, there has been no overall treatment of that kind of problems, though.
In this thesis, we provide a comprehensive treatment of containment problems concerning polyhedra, spectrahedra, and their projections from the viewpoint of low-degree semialgebraic problems and study algebraic certificates for containment. This leads to a new and systematic access to studying containment problems of (projections of) polyhedra and spectrahedra, and provides several new and partially unexpected results.
The main idea - which is meanwhile common in polynomial optimization, but whose understanding of the particular potential on low-degree geometric problems is still a major challenge - can be explained as follows. One point of view towards linear programming is as an application of Farkas' Lemma which characterizes the (non-)solvability of a system of linear inequalities. The affine form of Farkas' Lemma characterizes linear polynomials which are nonnegative on a given polyhedron. By omitting the linearity condition, one gets a polynomial nonnegativity question on a semialgebraic set, leading to so-called Positivstellensaetze (or, more precisely Nichtnegativstellensaetze). A Positivstellensatz provides a certificate for the positivity of a polynomial function in terms of a polynomial identity. As in the linear case, these Positivstellensaetze are the foundation of polynomial optimization and relaxation methods. The transition from positivity to nonnegativity is still a major challenge in real algebraic geometry and polynomial optimization.
With this in mind, several principal questions arise in the context of containment problems: Can the particular containment problem be formulated as a polynomial nonnegativity (or, feasibility) problem in a sophisticated way? If so, how are positivity and nonnegativity related to the containment question in the sense of their geometric meaning? Is there a sophisticated Positivstellensatz for the particular situation, yielding certificates for containment? Concerning the degree of the semialgebraic certificates, which degree is necessary, which degree is sufficient to decide containment?
Indeed, (almost) all containment problems studied in this thesis can be formulated as polynomial nonnegativity problems allowing the application of semialgebraic relaxations. Other than this general result, the answer to all the other questions (highly) depends on the specific containment problem, particularly with regard to its underlying geometry. An important point is whether the hierarchies coming from increasing the degree in the polynomial relaxations always decide containment in finitely many steps.
We focus on the containment problem of an H-polytope in a V-polytope and of a spectrahedron in a spectrahedron. Moreover, we address containment problems concerning projections of H-polyhedra and spectrahedra. This selection is justified by the fact that the mentioned containment problems are computationally hard and their geometry is not well understood.