Impedimetrischer DNA Nachweis - Schritte in Richtung sensorischer Anwendung

Diese Studie beschreibt einen labelfreien impedimetrischen Sensor auf der Grundlage von kurzen einzelsträngigen DNA-Erkennungselementen für den Nachweis von Hybridisierungsereignissen. Der Fokus der Arbeit liegt auf der Aufklärung des Einflusses der Ziel-DNA-Länge und der Erkennungssequenzposition auf die sensorische Leistungsfähigkeit. Die impedimetrischen Messungen werden in Anwesenheit des Redoxsystems Kaliumhexacyanoferrat (II/III) durchgeführt und zeigen einen Anstieg des Durchtrittswiderstandes nach der Hybridisierung mit komplementärer Ziel-DNA mit einer Nachweisgrenze im unteren nanomolaren Bereich. Nach der Hybridisierung kann die Regeneration des Sensors mit deionisiertem Wasser durch die Einstellung effektiver Konvektionsbedingungen erreicht werden und ermöglicht somit eine Wiederverwendbarkeit des Sensors. Untersuchungen zu längeren Ziel-DNA-Strängen mit einem zur Lösung exponierten Überhang demonstrieren die Anwendbarkeit des impedimetrischen Nachweises für längere Sequenzen. Allerdings resultiert eine zunehmende Überhanglänge in einer verringerten Durchtrittswiderstandsänderung. Um die Impedanzänderung für längere Ziel-DNA zu erhöhen, wird die Erkennungssequenzposition verändert, sodass ein kleiner Überhang zur Elektrode ausgerichtet ist. Die Ergebnisse legen nahe, dass DNA in direkter Nähe zur Elektrode einen größeren Einfluss auf das impedimetrische Signal besitzt als weiter entfernte DNA.This study describes a label-free impedimetric sensor based on short ssDNA recognition elements for the detection of hybridisation events. We concentrate on the elucidation of the influence of target length and recognition sequence position on the sensorial performance. The impedimetric measurements are performed in the presence of the redox system ferri-/ferrocyanide and show an increase in charge transfer resistance upon hybridisation of complementary ssDNA in the nanomolar range. After hybridisation, a sensor regeneration can be achieved with deionised water by adjustment of effective convection conditions, ensuring sensor reusability. By investigation of longer targets with overhangs exposed to the solution, we can demonstrate applicability of the impedimetric detection for longer ssDNA. However, a decreasing charge transfer resistance change (ΔRct) is found by extending the overhang. As a strategy to increase the impedance change for longer target strands, the position of the recognition sequence can be designed in a way that a small overhang is exposed to the electrode surface. These results suggest that DNA near the electrode possesses a larger impact on the impedimetric signal than DNA further away

Wie bereit sind Studierende für die Nutzung von KI-Technologien? Eine Annäherung an die KI-Readiness Studierender im Kontext des Projektes "tech4comp"

Der Einsatz von Anwendungen und Verfahren der Künsichen Intelligenz (KI) in der Hochschullehre wird zunehmend vorangetrieben. Gleichzeitig zeigen verschiedene Erhebungen, dass die Nutzung von KI-Technologien noch nicht weit verbreitet ist und diese teilweise skeptisch betrachtet werden. Der vorliegende Beitrag stellt auf Grundlage des Konzeptes der KI Readiness eine explorative, qualitative Erhebung unter Studierenden vor. Diese haben ein konkretes KI-Einsatzszenario in der Hochschullehre erlebt und anschließend dessen Nutzen für den Lernprozess reflektiert. Studierende erkennen demnach durchaus einen Mehrwert in dem atlngebotenen KI-Szenario und können sich vorstellen, dieses unterstützend für den Lernprozess zu nutzen. Eine menschliche Lernbegleitung erscheint ihnen jedoch aufgrund der empathischen Fähigkeiten und der Berücksichtigung individueller Bezugsnormen überlegen. (DIPF/Orig.

Synthesis and Characterization of Poly(hydrogen halide) Halogenates (–I)

Herein, we report the synthesis and characterization of a variety of novel poly(hydrogen halide) halogenates (−I). The bifluoride ion, which is known to have the highest hydrogen bond energy of ≈160 kJ mol−1, is the most famous among many examples of [X(HX)n]− anions (X=F, Cl) known in the literature. In contrast, little is known about poly(hydrogen halide) halogenates containing two different halogens, ([X(HY)n]−). In this work we present the synthesis of anions of the type [X(HY)n]− (X=Br, I, ClO4; Y=Cl, Br, CN) stabilized by the [PPh4]+ and [PPN]+ cation. The obtained compounds have been characterized by single‐crystal X‐ray diffraction, Raman spectroscopy and quantum‐chemical calculations. In addition, the behavior of halide ions in hydrogen fluoride was investigated by using experimental and quantum‐chemical methods in order to gain knowledge on the acidity of hydrogen halides in HF

High Frequencies of Theropod Bite Marks Provide Evidence for Feeding, Scavenging, and Possible Cannibalism in a Stressed Late Jurassic Ecosystem

Bite marks provide direct evidence for trophic interactions and competition in the fossil record. However, variations in paleoecological dynamics, such as trophic relationships, feeding behavior, and food availability, govern the frequency of these traces. Theropod bite marks are particularly rare, suggesting that members of this clade might not often focus on bone as a resource, instead preferentially targeting softer tissues. Here, we present an unusually large sample of theropod bite marks from the Upper Jurassic Mygatt-Moore Quarry (MMQ). We surveyed 2,368 vertebrate fossils from MMQ in this analysis, with 684 specimens (28.885% of the sample) preserving at least one theropod bite mark. This is substantially higher than in other dinosaur-dominated assemblages, including contemporaneous localities from the Morrison Formation. Observed bite marks include punctures, scores, furrows, pits, and striations. Striated marks are particularly useful, diagnostic traces generated by the denticles of ziphodont teeth, because the spacing of these features can be used to provide minimum estimates of trace maker size. In the MMQ assemblage, most of the striations are consistent with denticles of the two largest predators known from the site: Allosaurus and Ceratosaurus. One of the bite marks suggests that a substantially larger theropod was possibly present at the site and are consistent with large theropods known from other Morrison Formation assemblages (either an unusually large Allosaurus or a separate, large-bodied taxon such as Saurophaganax or Torvosaurus). The distribution of the bite marks on skeletal elements, particularly those found on other theropods, suggest that they potentially preserve evidence of scavenging, rather than active predation. Given the relative abundances of the MMQ carnivores, partnered with the size-estimates based on the striated bite marks, the feeding trace assemblage likely preserves the first evidence of cannibalism in Allosaurus

Ageing Effects in Mounting Media of Microscope Slide Samples from Natural History Collections: A Case Study with Canada Balsam and PermountTM

Microscope slide collections represent extremely valuable depositories of research material in a natural history, forensic, veterinary, and medical context. Unfortunately, most mounting media of these slides deteriorate over time, with the reason for this not yet understood at all. In this study, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, and different types of light microscopy were used to investigate the ageing behaviour of naturally aged slides from museum collections and the experimentally aged media of Canada balsam and PermountTM, representing a natural and a synthetic resin, respectively, with both being based on mixtures of various terpenes. Whereas Canada balsam clearly revealed chemical ageing processes, visible as increasing colouration, PermountTM showed physical deterioration recognisable by the increasing number of cracks, which even often impacted a mounted specimen. Noticeable changes to the chemical and physical properties of these mounting media take decades in the case of Canada balsam but just a few years in the case of PermountTM. Our results question whether or not Canada balsam should really be regarded as a mounting medium that lasts for centuries, if its increasing degree of polymerisation can lead to a mount which is no longer restorable.Deutsche ForschungsgemeinschaftPeer Reviewe

IL10-Deficiency in CD4+ T Cells Exacerbates the IFNγ and IL17 Response During Bacteria Induced Colitis

Background/Aims: IL10 is a key inhibitor of effector T cell activation and a mediator of intestinal homeostasis. In addition, IL10 has emerged as a key immunoregulator during infection with various pathogens, ameliorating the excessive T-cell responses that are responsible for much of the immunopathology associated with the infection. Because IL10 plays an important role in both intestinal homeostasis and infection, we studied the function of IL10 in infection-associated intestinal inflammation. Methods: Wildtype mice and mice deficient in CD4+ T cell-derived or regulatory T cells-derived IL10 were infected with the enteric pathogen Citrobacter (C.) rodentium and analyzed for the specific immune response and pathogloy in the colon. Results: We found that IL10 expression is upregulated in colonic tissue after infection with C. rodentium, especially in CD4+ T cells, macrophages and dendritic cells. Whereas the deletion of IL10 in regulatory T cells had no effect on C. rodentium induced colitis, infection of mice deficient in CD4+ T cell-derived IL10 exhibited faster clearance of the bacterial burden but worse colitis, crypt hyperplasia, and pathology than did WT mice. In addition, the depletion of CD4+ T cell-derived IL10 in infected animals was accompanied by an accelerated IFNγ and IL17 response in the colon. Conclusion: Thus, we conclude that CD4+ T cell-derived IL10 is strongly involved in the control of C. rodentium-induced colitis. Interference with this network could have implications for the treatment of infection-associated intestinal inflammation

A Cell-Free System for Regulated Exocytosis in Pc12 Cells

We have developed a cell-free system for regulated exocytosis in the PC12 neuroendocrine cell line. Secretory vesicles were preloaded with acridine orange in intact cells, and the cells were sonicated to produce flat, carrier-supported plasma membrane patches with attached vesicles. Exocytosis resulted in the release of acridine orange which was visible as a disappearance of labeled vesicles and, under optimal conditions, produced light flashes by fluorescence dequenching. Exocytosis in vitro requires cytosol and Ca2+ at concentrations in the micromolar range, and is sensitive to Tetanus toxin. Imaging of membrane patches at diffraction- limited resolution revealed that 42% of docked granules were released in a Ca2+-dependent manner dur- ing 1 min of stimulation. Electron microscopy of membrane patches confirmed the presence of dense-core vesicles. Imaging of membrane patches by atomic force microscopy revealed the presence of numerous particles attached to the membrane patches which decreased in number upon stimula- tion. Thus, exocytotic membrane fusion of single vesicles can be monitored with high temporal and spatial resolution, while providing access to the site of exocytosis for biochemical and molecular tools

Does maternal genetic liability to folate deficiency influence the risk of antiseizure medication-associated language impairment and autistic traits in children of women with epilepsy?

Background: Prenatal exposure to antiseizure medication (ASM) may lead to low plasma folate concentrations and is associated with impaired neurodevelopment. Objectives: To examine whether maternal genetic liability to folate deficiency interacts with ASM-associated risk of language impairment and autistic traits in children of women with epilepsy. Methods: We included children of women with and without epilepsy and with available genetic data enrolled in the Norwegian Mother, Father, and Child Cohort Study. Information on ASM use, folic acid supplement use and dose, dietary folate intake, child autistic traits, and child language impairment was obtained from parent-reported questionnaires. Using logistic regression, we examined the interaction between prenatal ASM exposure and maternal genetic liability to folate deficiency expressed as polygenic risk score of low folate concentrations or maternal rs1801133 genotype (CC or CT/TT) on risk of language impairment or autistic traits. Results: We included 96 children of women with ASM-treated epilepsy, 131 children of women with ASM-untreated epilepsy, and 37,249 children of women without epilepsy. The polygenic risk score of low folate concentrations did not interact with the ASM-associated risk of language impairment or autistic traits in ASM-exposed children of women with epilepsy compared with ASM-unexposed children aged 1.5–8 y. ASM-exposed children had increased risk of adverse neurodevelopment regardless of maternal rs1801133 genotype {adjusted odds ratio [aOR] for language impairment aged 8 y was 2.88 [95% confidence interval (CI): 1.00, 8.26] if CC and aOR 2.88 [95% CI: 1.10, 7.53] if CT/TT genotypes}. In children of women without epilepsy aged 3 y, those with maternal rs1801133 CT/TT compared with CC genotype had increased risk of language impairment (aOR: 1.18; 95% CI: 1.05, 1.34). Conclusions: In this cohort of pregnant women reporting widespread use of folic acid supplements, maternal genetic liability to folate deficiency did not significantly influence the ASM-associated risk of impaired neurodevelopment.publishedVersio