Continuous endosomes form functional subdomains and orchestrate rapid membrane trafficking in trypanosomes.

Endocytosis is a common process observed in most eukaryotic cells, although its complexity varies among different organisms. In Trypanosoma brucei, the endocytic machinery is under special selective pressure because rapid membrane recycling is essential for immune evasion. This unicellular parasite effectively removes host antibodies from its cell surface through hydrodynamic drag and fast endocytic internalization. The entire process of membrane recycling occurs exclusively through the flagellar pocket, an extracellular organelle situated at the posterior pole of the spindle-shaped cell. The high-speed dynamics of membrane flux in trypanosomes do not seem compatible with the conventional concept of distinct compartments for early endosomes (EE), late endosomes (LE), and recycling endosomes (RE). To investigate the underlying structural basis for the remarkably fast membrane traffic in trypanosomes, we employed advanced techniques in light and electron microscopy to examine the three-dimensional architecture of the endosomal system. Our findings reveal that the endosomal system in trypanosomes exhibits a remarkably intricate structure. Instead of being compartmentalized, it constitutes a continuous membrane system, with specific functions of the endosome segregated into membrane subdomains enriched with classical markers for EE, LE, and RE. These membrane subdomains can partly overlap or are interspersed with areas that are negative for endosomal markers. This continuous endosome allows fast membrane flux by facilitated diffusion that is not slowed by multiple fission and fusion events.

Alpha-tACS alters attentional control but not cognitive functions as video games do: A psychophysical investigation based on the theory of visual attention.

Video game players' faster speed of information processing has been shown to coincide with altered posterior alpha power modulation, that is, brain oscillatory activity around 10 Hz. Thus, it was proposed that improved cognitive processing in video game players may be related to differential alpha activity. However, a causal relationship thereof has not yet been established. We addressed this by conducting a non-invasive brain stimulation study to demonstrate that modulating alpha power using transcranial alternating current stimulation (tACS) may impact on speed of information processing. Furthermore, we aimed to show that this effect correlated with altered attentional control, for example, visuospatial attention and/or top-down control processing, given that this has been suggested to contribute to video gaming effects. Therefore, we recruited 19 non-video game players to undergo one of five brain stimulation conditions while performing a visual short-term memory task at five different days, respectively. Thus, we applied tACS either at 10 Hz (alpha frequency) or at 16.18 Hz (control frequency) either over their left or right posterior parietal cortex (PPC) or a sham stimulation. Individuals' speed of information processing, visuospatial attention and top-down control processing were operationalised using a computational modelling approach based on the theory of visual attention. We found that alpha-tACS applied over individuals' left PPC altered their visuospatial attention orientation but not their speed of information processing. Thus, we were not able to establish a causal relationship between speed of information processing and altered visuospatial attention processing through alpha power modulation using non-invasive brain stimulation.

A survey among physicians in surgery and anesthesiology departments after the first surge of SARS-CoV-2 infections in Germany : Preparing for further challenges ahead.

BACKGROUND: The SARS-CoV­2 pandemic has extensively challenged healthcare systems all over the world. Many elective operations were postponed or cancelled, changing priorities and workflows in surgery departments. AIMS: The primary aim of this cross-sectional study was to assess the workload and psychosocial burden of surgeons and anesthesiologists, working in German hospitals during the first wave of SARS-CoV­2 infections in 2020. METHODS: Quantitative online survey on the workplace situation including psychosocial and work-related stress factors among resident and board-certified surgeons and anesthesiologists. Physicians in German hospitals across all levels of healthcare were contacted via departments, professional associations and social media posts. RESULTS: Among 154 total study participants, 54% of respondents stated a lack of personal protective equipment in their own wards and 56% reported increased staff shortages since the onset of the pandemic. While routine practice was reported as fully resumed in 71% of surgery departments at the time of the survey, work-related dissatisfaction among responding surgeons and anesthesiologists increased from 24% before the pandemic to 36% after the first wave of infections. As a countermeasure, 94% of participants deemed the establishment of action plans to increase pandemic preparedness and strengthening German public health systems a useful measure to respond to current challenges. CONCLUSION: The aftermath of the first wave of SARS-CoV­2 infections in Germany has left the surgical staff strained, despite temporarily decreased workloads. Overall, a critical review of the altered conditions is indispensable to identify and promote effective solutions and prudent action plans required to address imminent challenges.

The Glycosylphosphatidylinositol Anchor: A Linchpin for Cell Surface Versatility of Trypanosomatids.

The use of glycosylphosphatidylinositol (GPI) to anchor proteins to the cell surface is widespread among eukaryotes. The GPI-anchor is covalently attached to the C-terminus of a protein and mediates the protein's attachment to the outer leaflet of the lipid bilayer. GPI-anchored proteins have a wide range of functions, including acting as receptors, transporters, and adhesion molecules. In unicellular eukaryotic parasites, abundantly expressed GPI-anchored proteins are major virulence factors, which support infection and survival within distinct host environments. While, for example, the variant surface glycoprotein (VSG) is the major component of the cell surface of the bloodstream form of African trypanosomes, procyclin is the most abundant protein of the procyclic form which is found in the invertebrate host, the tsetse fly vector. Trypanosoma cruzi, on the other hand, expresses a variety of GPI-anchored molecules on their cell surface, such as mucins, that interact with their hosts. The latter is also true for Leishmania, which use GPI anchors to display, amongst others, lipophosphoglycans on their surface. Clearly, GPI-anchoring is a common feature in trypanosomatids and the fact that it has been maintained throughout eukaryote evolution indicates its adaptive value. Here, we explore and discuss GPI anchors as universal evolutionary building blocks that support the great variety of surface molecules of trypanosomatids.

To the Surface and Back: Exo- and Endocytic Pathways in Trypanosoma brucei.

Trypanosoma brucei is one of only a few unicellular pathogens that thrives extracellularly in the vertebrate host. Consequently, the cell surface plays a critical role in both immune recognition and immune evasion. The variant surface glycoprotein (VSG) coats the entire surface of the parasite and acts as a flexible shield to protect invariant proteins against immune recognition. Antigenic variation of the VSG coat is the major virulence mechanism of trypanosomes. In addition, incessant motility of the parasite contributes to its immune evasion, as the resulting fluid flow on the cell surface drags immunocomplexes toward the flagellar pocket, where they are internalized. The flagellar pocket is the sole site of endo- and exocytosis in this organism. After internalization, VSG is rapidly recycled back to the surface, whereas host antibodies are thought to be transported to the lysosome for degradation. For this essential step to work, effective machineries for both sorting and recycling of VSGs must have evolved in trypanosomes. Our understanding of the mechanisms behind VSG recycling and VSG secretion, is by far not complete. This review provides an overview of the trypanosome secretory and endosomal pathways. Longstanding questions are pinpointed that, with the advent of novel technologies, might be answered in the near future.

Sepsis Diagnostics: Intensive Care Scoring Systems Superior to MicroRNA Biomarker Testing.

Sepsis represents a serious medical problem accounting for numerous deaths of critically ill patients in intensive care units (ICUs). An early, sensitive, and specific diagnosis is considered a key element for improving the outcome of sepsis patients. In addition to classical laboratory markers, ICU scoring systems and serum miRNAs are discussed as potential sepsis biomarkers. In the present prospective observational study, the suitability of miRNAs in sepsis diagnosis was tested based on proper validated and normalized data (i.e., absolute quantification by means of Droplet Digital PCR (ddPCR)) in direct comparison to classical sepsis markers and ICU scores within the same patient cohort. Therefore, blood samples of septic intensive care patients (n = 12) taken at day of admission at ICU were compared to non-septic intensive care patients (n = 12) and a healthy control group (n = 12). Our analysis indicates that all tested biomarkers have only a moderate informative power and do not allow an unequivocal differentiation between septic and non-septic ICU patients. In conclusion, there is no standalone laboratory parameter that enables a reliable diagnosis of sepsis. miRNAs are not superior to classical parameters in this respect. It seems recommendable to measure multiple parameters and scores and to interpret them with regard to the clinical presentation.

The Idea of Volk and the Origins of Völkisch Research, 1800-1930s.

Völkisch research was a phenomenon in the social sciences and humanities that aimed to describe and cultivate the Volk, conceived broadly as a group united by some pre-existing or transcendental bond. Studies of this research complex have thus far been dominated by questions related to its close affiliation with the Nazi regime, but much remains unknown about how its longer-term development related to the transformation of science or to conceptual changes in the notion of Volk. This article addresses these questions by tracing the ways in which the idea of Volk transformed through accommodation with shifting scientific norms.

Author Correction: Identification of stably expressed housekeeping miRNAs in endothelial cells and macrophages in an inflammatory setting.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Identification of stably expressed housekeeping miRNAs in endothelial cells and macrophages in an inflammatory setting.

Reliable quantification of miRNA expression by qRT-PCR crucially depends on validated housekeepers for data normalization. Here we present thoroughly tested miRNAs eligible as references in immunological studies utilizing endothelial cells and macrophages, respectively. Endothelial cells (cell line: TIME) and macrophages (cell line: RAW264.7) were treated with various pro- and anti-inflammatory mediators (cytokines, LPS, unsaturated fatty acids) given as either single substances or in combination. Isolated RNA was screened for stably expressed miRNAs by next generation sequencing. Housekeeper candidates were thereafter validated by means of two independent quantification techniques: qRT-PCR for relative quantification and ddPCR for absolute quantification. Both methods consistently confirmed the suitability of let-7g-5p, let-7i-5p, miR-127-3p and miR-151a-5p in cytokine/fatty acid-treated TIME and miR-16-5p, miR-27b-3p, miR-103a-3p and miR-423-3p in LPS/fatty acid-treated RAW264.7, respectively as housekeeping miRNAs. With respect to abundancy and over all expression stability the miRNAs miR-151a-5p (cell line: TIME) as well as miR-27b-3p and miR-103a-3p (cell line: RAW264.7) can be particularly recommended for normalization of qRT-PCR data.

[Disciplinary non-consolidation. On the original of medieval archaeology in the 1920s and the 1930s]. / Disziplinäre Nichtkonsolidierung: Zu den Anfängen der Mittelalterarchäologie in den 1920er und 1930er Jahren.

This article investigates the roots of the sub-discipline medieval archaeology that emerged in German-speaking universities in the 1950s and 1960s. In the 1930s, research practices crucial for the formation of medieval archaeology, such as the investigation of medieval castles and peasant houses, became more prominent in the humanities, especially in the context of vilkisch research. After the Nazis took power in Germany, they encouraged such research because it built a scientific basis for their nationalist policy. This politically motivated funding did not result in a new discipline, in contrast to research fields such as prehistory and folklore studies. In this article, I propose two explanations for why medieval archaeology did not emerge as an interdisciplinary research field in the 1930s and 1940s, even though the course was set for its development. First, for archaeologists, art historians, and regional medieval historians, research objects such as medieval castles were semantically too indeterminate. Archaeologists would investigate a castle as a building completely destroyed and buried under rubble, while art historians would be interested in its building technique, and regional medieval historians in its written record. Second, disciplines that were important for the creation of medieval archaeology, such as prehistoric archaeology, art history, and regional medieval history, structurally did not allow for the emergence of an interdisciplinary research field in the 1930s. In particular, prehistoric archaeology, which was crucial for the development of medieval archaeology, itself was not fully institutionalized at universities in the 1930s. This institutionalization process prevented the emergence and development of an interdisciplinary research field such as medieval archaeology To demonstrate this argument, I draw on two examples of investigations of castles, one in Nazi Germany and the other in the German-speaking part of Switzerland.