Wirkungen des Energiepflanzenanbaus auf die natürlichen Ressourcen Boden und Wasser

Maisanbau birgt u.a. aufgrund der späten Entwicklung von Mais das Risiko unerwünschter Nitratauswaschungen in das Grundwasser. Die Durchwachsene Silphie (Silphium perfoliatum L.), eine der ertragsstärksten alternativen Biogaspflanzen zum Mais, könnte dieses Risiko als perennierende Staude mit längerer Bodendeckung und intensiver Durchwurzelung des Bodens verringern. Zudem könnte aufgrund der fehlenden Bodenbearbeitung die Wasserinfiltration verbessert, der Bodenabtrag durch Erosion vermindert sowie der Gehalt an organischer Bodensubstanz im Vergleich zum Maisanbau erhöht werden. Zur Überprüfung dieser Hypothesen wird ein seit 2012 laufender Feldversuch mit dem Ziel des Vergleichs zwischen Mais und Silphie sowie Feldgras verwendet. Als zusätzlicher Faktor wird ab 2017 die Hälfte der Parzellen einer Starkregensimulation unterzogen. Zur Messung der N-Auswaschungen wurden im Herbst 2016 Passivsammler, sogenannte Selbst-Integrierende Akkumulatoren (SIA), im Versuch eingebaut, die ebenso wie der Gehalt an organischem C, Gesamt-N sowie mineralisiertem N bis 90 cm Tiefe halbjährlich analysiert werden. Weiterhin werden der Niederschlagsabfluss von den Parzellen und die damit verbundene Bodenerosion sowie die Infiltrationskapazität, die Aggregatstabilität und die Lagerungsdichte des Bodens bestimmt. Erste Ergebnisse aus dem Herbst 2016 zeigen mit 9,2 im Vergleich zu 8,4 g C kg-1 Boden signifikant erhöhte C-Gehalte im Oberboden der Silphie-Parzellen im Vergleich zu Mais, außerdem mit 28,6, 16,6, und 9,3 kg N ha-1 signifikant unterschiedliche Gehalte an Nmin bis 90 cm Tiefe in der Abfolge Mais > Feldgras > Silphie. Die Aggregatstabilität im Oberboden wurde durch Feldgras im Vergleich zu Mais weiterhin mit 79,7 im Vergleich zu 74,9 % signifikant erhöht. Infolge einer Schneeschmelze im Januar 2017 konnte zudem ein vielfach höherer Abfluss auf den Mais- im Vergleich zu den Feldgras- und Silphie-Parzellen festgestellt werden. Diese Ergebnisse deuten auf Vorteile sowohl der Silphie als auch des Feldgrases gegenüber Mais bezüglich des Boden- und Wasserschutzes hin. Weiterführende Untersuchungen werden detailliertere Schlussfolgerungen zulassen

Aharonov-Bohm signature for neutral excitons in type-II quantum dot ensembles

It is commonly believed that the Aharonov-Bohm (AB) effect is a typical feature of the motion of a charged particle interacting with the electromagnetic vector potential. Here we present a magnetophotoluminescence study of type-II InP/GaAs self-assembled quantum dots, unambiguously revealing the Aharonov-Bohm-type oscillations for neutral excitons when the hole ground state changes its angular momentum from lh = 0 to lh = 1, 2, and 3. The hole ring parameters derived from a simple model are in excellent agreement with the structural parameters for this system.Comment: Revised version, 10 pages, 3 figure

Soil moisture and matric potential-an open field comparison of sensor systems

Soil water content and matric potential are central hydrological state variables. A large variety of automated probes and sensor systems for state monitoring exist and are frequently applied. Most applications solely rely on the calibration by the manufacturers. Until now, there has been no commonly agreed-upon calibration procedure. Moreover, several opinions about the capabilities and reliabilities of specific sensing methods or sensor systems exist and compete. A consortium of several institutions conducted a comparison study of currently available sensor systems for soil water content and matric potential under field conditions. All probes were installed at 0.2mb.s. (metres below surface), following best-practice procedures. We present the set-up and the recorded data of 58 probes of 15 different systems measuring soil moisture and 50 further probes of 14 different systems for matric potential. We briefly discuss the limited coherence of the measurements in a cross-correlation analysis. The measuring campaign was conducted during the growing period of 2016. The monitoring data, results from pedophysical analyses of the soil and laboratory reference measurements for calibration are published in Jackisch et al. (2018, https://doi.org/10.1594/PANGAEA.892319)

Plasmodium berghei Hsp90 contains a natural immunogenic I-A^b-restricted antigen common to rodent and human Plasmodium species

Thorough understanding of the role of CD4 T cells in immunity can be greatly assisted by the study of responses to defined specificities. This requires knowledge of Plasmodium-derived immunogenic epitopes, of which only a few have been identified, especially for the mouse C57BL/6 background. We recently developed a TCR transgenic mouse line, termed PbT-II, that produces CD4+ T cells specific for an MHC class II (I-Ab)-restricted Plasmodium epitope and is responsive to both sporozoites and blood-stage P. berghei. Here, we identify a peptide within the P. berghei heat shock protein 90 as the cognate epitope recognised by PbT-II cells. We show that C57BL/6 mice infected with P. berghei blood-stage induce an endogenous CD4 T cell response specific for this epitope, indicating cells of similar specificity to PbT-II cells are present in the naïve repertoire. Adoptive transfer of in vitro activated TH1-, or particularly TH2-polarised PbT-II cells improved control of P. berghei parasitemia in C57BL/6 mice and drastically reduced the onset of experimental cerebral malaria. Our results identify a versatile, potentially protective MHC-II restricted epitope useful for exploration of CD4 T cell-mediated immunity and vaccination strategies against malaria

Influence of Humidity on Microtribology of Vertically Aligned Carbon Nanotube Film

The aim of this study is to probe the influence of water vapor environment on the microtribological properties of a forestlike vertically aligned carbon nanotube (VACNT) film, deposited on a silicon (001) substrate by chemical vapor deposition. Tribological experiments were performed using a gold tip under relative humidity varying from 0 to 100%. Very low adhesion forces and high friction coefficients of 0.6 to 1.3 resulted. The adhesion and friction forces were independent of humidity, due probably to the high hydrophobicity of VACNT. These tribological characteristics were compared to those of a diamond like carbon (DLC) sample

Skeletal muscle NOX4 is required for adaptive responses that prevent insulin resistance

Reactive oxygen species (ROS) generated during exercise are considered integral for the health-promoting effects of exercise. However, the precise mechanisms by which exercise and ROS promote metabolic health remain unclear. Here, we demonstrate that skeletal muscle NADPH oxidase 4 (NOX4), which is induced after exercise, facilitates ROS-mediated adaptive responses that promote muscle function, maintain redox balance, and prevent the development of insulin resistance. Conversely, reductions in skeletal muscle NOX4 in aging and obesity contribute to the development of insulin resistance. NOX4 deletion in skeletal muscle compromised exercise capacity and antioxidant defense and promoted oxidative stress and insulin resistance in aging and obesity. The abrogated adaptive mechanisms, oxidative stress, and insulin resistance could be corrected by deleting the H2O2-detoxifying enzyme GPX-1 or by treating mice with an agonist of NFE2L2, the master regulator of antioxidant defense. These findings causally link NOX4-derived ROS in skeletal muscle with adaptive responses that promote muscle function and insulin sensitivity

Genetic and epigenetic characterization of posterior pituitary tumors

Pituicytoma (PITUI), granular cell tumor (GCT), and spindle cell oncocytoma (SCO) are rare tumors of the posterior pituitary. Histologically, they may be challenging to distinguish and have been proposed to represent a histological spectrum of a single entity. We performed targeted next-generation sequencing, DNA methylation profiling, and copy number analysis on 47 tumors (14 PITUI; 12 GCT; 21 SCO) to investigate molecular features and explore possibilities of clinically meaningful tumor subclassification. We detected two main epigenomic subgroups by unsupervised clustering of DNA methylation data, though the overall methylation differences were subtle. The largest group (n = 23) contained most PITUIs and a subset of SCOs and was enriched for pathogenic mutations within genes in the MAPK/PI3K pathways (12/17 [71%] of sequenced tumors: FGFR1 (3), HRAS (3), BRAF (2), NF1 (2), CBL (1), MAP2K2 (1), PTEN (1)) and two with accompanying TERT promoter mutation. The second group (n = 16) contained most GCTs and a subset of SCOs, all of which mostly lacked identifiable genetic drivers. Outcome analysis demonstrated that the presence of chromosomal imbalances was significantly associated with reduced progression-free survival especially within the combined PITUI and SCO group (p = 0.031). In summary, we observed only subtle DNA methylation differences between posterior pituitary tumors, indicating that these tumors may be best classified as subtypes of a single entity. Nevertheless, our data indicate differences in mutation patterns and clinical outcome. For a clinically meaningful subclassification, we propose a combined histo-molecular approach into three subtypes: one subtype is defined by granular cell histology, scarcity of identifiable oncogenic mutations, and favorable outcome. The other two subtypes have either SCO or PITUI histology but are segregated by chromosomal copy number profile into a favorable group (no copy number changes) and a less favorable group (copy number imbalances present). Both of the latter groups have recurrent MAPK/PI3K genetic alterations that represent potential therapeutic targets

Point centromeres contain more than a single centromere-specific Cse4 (CENP-A) nucleosome

Quantitative measurement of the number of Cse4, CBF3, and Ndc80 proteins at kinetochores reveals a 2.5–3-fold increased copy number relative to prior estimates