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ZusammenfassungSocial Media beherrschen nicht nur die private Kommunikation, sondern haben zunehmend auch Einfluss auf die externe Wissenschaftskommunikation. In bisherigen Forschungsarbeiten wurden zwar bereits Social Media und deren Nutzung durch Wissenschaftler*innen in Zusammenhang mit wissenschaftsexterner Kommunikation untersucht, allerdings mangelt es an einer systematischen Darstellung der Einflussfaktoren. Diese Arbeit möchte an vorangegangene Studien anknüpfen und die gefundenen Einflussfaktoren replizieren und verifizieren. Als maßgebliche Einflussfaktoren bei der Social-Media-Nutzung von Wissenschaftler*innen haben wir basierend auf dem Forschungsstand Disziplinzugehörigkeit, den beruflichen Kontext, persönliche Eigenschaften und Prädispositionen definiert. Untersucht wurde die Häufigkeit der Nutzung von Facebook, Twitter, Instagram, YouTube, Snapchat sowie von Blogs und Podcasts. In einer aufwändig angelegten Online-Befragung haben wir zunächst Wissenschaftler*innen von 21 deutschen Volluniversitäten zur Teilnahme an der Studie eingeladen. Die Rekrutierung erfolgte über Dekanate und Institute und führte zu einer Stichprobe von über 1100 Wissenschaftler*innen. Lediglich Facebook und Twitter erwiesen sich für die Kommunikation im wissenschaftsexternen Kontext als relevant. Nach einer binär-logistischen Regressionsanalyse zeigte sich, dass die Ergebnisse bisheriger Studien nur vereinzelt bestätigt werden konnte. Faktoren wie Disziplinzugehörigkeit, Qualifikationsstufe und Alter haben eine nur mäßig gute Erklärkraft. Der Social-Media-Typus der Hochschule, das Geschlecht, Technikaffinität oder -abneigung sowie Persönlichkeitsfaktoren erwiesen sich als nicht signifikant. Die eher geringen R‑Quadrat-Werte in allen Modellen legen nahe, dass die unabhängigen Variablen nicht in der Lage sind, die abhängigen Variablen ausreichend gut zu erklären. Somit bedarf es weiterer Forschung, die insbesondere auch Faktoren des Einflusses auf das Public Engagement von Wissenschaftler*innen unabhängig vom Kommunikationsmedium einbezieht.

Materials circular economy 4(1), 5 (2022). doi:10.1007/s42824-021-00040-4, Published by Springer Nature Switzerland AG, Cham

Natural fibres have a high potential as reinforcement of polymer matrices, as they combine a high specific strength and modulus with sustainable production and reasonable prices. Modifying the fibre surface is a common method to increase the adhesion and thereby enhance the mechanical properties of composites. In this study, a novel sustainable surface treatment is presented: the fungal enzyme laccase was utilised with the aim of covalently binding the coupling agent dopamine to flax fibre surfaces. The goal is to improve the interfacial strength towards an epoxy matrix. SEM and AFM micrographs showed that the modification changes the surface morphology, indicating a deposition of dopamine on the surface. Fibre tensile tests, which were performed to check whether the fibre structure was damaged during the treatment, showed that no decrease in tensile strength or modulus occurred. Single fibre pullout tests showed a 30% increase in interfacial shear strength (IFSS) due to the laccase-mediated bonding of the coupling agent dopamine. These results demonstrate that a laccase + dopamine treatment modifies flax fibres sustainably and increases the interfacial strength towards epoxy.

In high-income countries, a high proportion of cervical cancers is diagnosed in screening non-attendees. One approach to improve screening coverage is to offer self-sampling for human papillomavirus (HPV) testing. However, especially young women are often HPV positive without having a precancerous lesion in need of treatment. To improve the rather low specificity of HPV testing additional markers such as DNA-methylation can be used. The aim of this feasibility study was to examine the performance of the methylation marker assay GynTect®, comprising six methylation markers, on dry self-collected cervico-vaginal samples compared to physician-taken samples.We recruited 89 patients from our colposcopy clinic of whom 87 qualified for the study. The women took a self-sample with the Evalyn-Brush. Afterwards the planned colposcopy was performed and smears for cytology and reference HPV testing were taken as well as a biopsy in cases of abnormalities. Physician-taken and self-collected samples were tested for HPV DNA and were analyzed with GynTect®.We obtained 95.5 % valid results for the self-collected samples which was very close to the physician-taken samples. Only about half of the self-collected samples were GynTect® positive in comparison to the physician-taken samples. GynTect® scores were significantly lower for self-collected than for physician-taken samples (p = 0.001, paired t-test). The overall concordance for GynTect® results was moderate (kappa 0.394; p0.001). For HPV testing we obtained a good concordance (kappa 0.586; p0.001). The GynTect® results for the self-collected samples showed a sensitivity for the detection of cervical intraepithelial neoplasia 2 or worse (CIN2+) of 26.1 % (95 %-CI: 0.13-0.46) and a specificity of 95.6 % (95 %-CI: 0.85-0.99), in comparison to a sensitivity of 45.5 % (95 %-CI: 0.27-0.65) and a specificity of 78.3 % (95 %-CI: 0.64-0.88) for the physician-taken samples.GynTect® methylation marker testing has a satisfactory amount of valid results on self-collected samples. However, the results of the self-collected samples differed clearly in comparison to the reference samples. To justify an application in screening, a larger study with more cases of high-grade cervical dysplasia and HPV positive patients will be needed.

Ras is a prototypical small G-protein and a central regulator of growth, proliferation and differentiation processes in virtually every nucleated cell. As such, Ras becomes engaged and activated by multiple growth factors, mitogens, cytokines or adhesion receptors. Ras activation comes about by changes in the steady-state equilibrium between the inactive guanosine diphosphate (GDP)-bound and active guanosine triphosphate (GTP)-bound states of Ras, resulting in the mostly transient accumulation of Ras-GTP. Three decades of intense Ras research have disclosed various families of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs) as the two principal regulatory elements of the Ras-GDP/GTP loading status. However, with the possible exception of the GEF Sos, we still have only a rudimentary knowledge of the precise role played by many GEF and GAP members in the signalling network upstream of Ras. As for GAPs, we even lack the fundamental understanding of whether they function as genuine signal transducers in the context of growth factor-elicited Ras activation or rather act as passive modulators of the Ras-GDP/GTP cycle. Here we sift through the large body of Ras literature and review the relevant data for understanding the participation and precise role played by GEFs and GAPs in the process of Ras activation.

Background Growth factors induce a characteristically short-lived Ras activation in cells emerging from quiescence. Extensive work has shown that transient as opposed to sustained Ras activation is critical for the induction of mitogenic programs. Mitogen-induced accumulation of active Ras-GTP results from increased nucleotide exchange driven by the nucleotide exchange factor Sos. In contrast, the mechanism accounting for signal termination and prompt restoration of basal Ras-GTP levels is unclear, but has been inferred to involve feedback inhibition of Sos. Remarkably, how GTP-hydrolase activating proteins (GAPs) participate in controlling the rise and fall of Ras-GTP levels is unknown. Results Monitoring nucleotide exchange of Ras in permeabilized cells we find, unexpectedly, that the decline of growth factor-induced Ras-GTP levels proceeds in the presence of unabated high nucleotide exchange, pointing to GAP activation as a major mechanism of signal termination. Experiments with non-hydrolysable GTP analogues and mathematical modeling confirmed and rationalized the presence of high GAP activity as Ras-GTP levels decline in a background of high nucleotide exchange. Using pharmacological and genetic approaches we document a raised activity of the neurofibromatosis type I tumor suppressor Ras-GAP neurofibromin and an involvement of Rsk1 and Rsk2 in the down-regulation of Ras-GTP levels. Conclusions Our findings show that, in addition to feedback inhibition of Sos, feedback stimulation of the RasGAP neurofibromin enforces termination of the Ras signal in the context of growth-factor signaling. These findings ascribe a precise role to neurofibromin in growth factor-dependent control of Ras activity and illustrate how, by engaging Ras-GAP activity, mitogen-challenged cells play safe to ensure a timely termination of the Ras signal irrespectively of the reigning rate of nucleotide exchange. Electronic supplementary material The online version of this article (doi:10.1186/s12964-016-0128-z) contains supplementary material, which is available to authorized users.

Woody crops such as poplars (Populus) can contribute to meet the increasing energy demand of a growing human population and can therefore enhance the security of energy supply. Using energy from biomass increases ecological sustainability as biomass is considered to play a pivotal role in abating climate change. Because areas for establishing poplar plantations are often confined to marginal sites drought tolerance is one important trait for poplar genotypes cultivated in short rotation coppice. We tested 9-month-old plants of four tetraploid Populus tremula (L.) × P. tremuloides (Michx.) lines that were generated by protoplast fusion and their diploid counterpart for water consumption and drought stress responses in a greenhouse experiment. The fusion lines showed equivalent or decreased height growth, stem biomass and total leaf area compared to the diploid line. The relative height increment of the fusion lines was not reduced compared to the diploid line when the plants were exposed to drought. The fusion lines were distinguished from the diploid counterpart by stomatal characteristics such as increased size and lower density. The changes in the stomatal apparatus did not affect the stomatal conductance. When exposed to drought the carbohydrate concentrations increased more strongly in the fusion lines than in the diploid line. Two fusion lines consumed significantly less water with regard to height growth, producing equivalent or increased relative stem biomass under drought compared to their diploid relative. Therefore, these tetraploid fusion lines are interesting candidates for short rotation biomass plantation on dry sites.

Ras GTPases undergo post-translational modifications that govern their subcellular trafficking and localization. In particular, palmitoylation of the Golgi tags N-Ras and H-Ras for exocytotic transport and residency at the PM (plasma membrane). Following depalmitoylation, PM-Ras redistributes to all subcellular membranes causing an accumulation of palmitate-free Ras at endomembranes, including the Golgi and endoplasmic reticulum. Palmitoylation is unanimously regarded as a critical modification at the crossroads of Ras activity and trafficking control, but its precise relevance to native wild-type Ras function in growth factor signalling is unknown. We show in the present study by use of palmitoylation-deficient N-Ras mutants and via the analysis of palmitate content of agonist-activated GTP-loaded N-Ras that only palmitoylated N-Ras becomes activated by agonists. In line with an essential role of palmitoylation in Ras activation, dominant-negative RasS17N loses its blocking potency if rendered devoid of palmitoylation. Live-cell Ras–GTP imaging shows that N-Ras activation proceeds only at the PM, consistent with activated N-Ras–GTP being palmitoylated. Finally, palmitoylation-deficient N-Ras does not sustain EGF (epidermal growth factor) or serum-elicited mitogenic signalling, confirming that palmitoylation is essential for signal transduction by N-Ras. These findings document that N-Ras activation proceeds at the PM and suggest that depalmitoylation, by removing Ras from the PM, may contribute to the shutdown of Ras signalling.

A large chondroitin sulfate proteoglycan (CSPG) identified in embryonic chick brain, and synthesized exclusively by neurons in a developmentally expressed pattern that coincides with migration and establishment of neuronal nuclei, reacts with a monoclonal antibody (S103L) developed against the cartilage-specific CSPG, aggrecan. The relationship of the brain and cartilage S103L CSPGs was established by chemical, biosynthetic and molecular analyses. Significant posttranslational differences (absence of keratan sulfate (KS), less CS, and different sulfation patterns) distinguish the brain S103L species from the cartilage S103L species. However, quantitative and qualitative Northern analysis, cassette RT-PCR and direct cloning and sequencing of the entire brain-specific S103L CSPG coding sequence, all indicate that the brain and cartilage core proteins are identical. Thus, although the S103L CSPG synthesized by chick brain and cartilage are the product of a single gene, they are clearly biochemically distinct and differentially expressed proteoglycan products, suggesting tissue specific roles for these proteoglycan homologs.