Mechanistic investigation of eukaryotic quality control factors RQT and Mbf1

Translation is a central cellular process and thus tightly regulated by quality control mechanisms. Monitoring the ribosome during translation is an elegant way to track the progress and to catch a variety of errors before they lead to detrimental effects in the cell. Recently, ribosomal collisions have emerged as a trigger for such quality control pathways, and various collision sensors have been identified. One of those pathways called ribosome associated quality control (RQC) deals with ribosomes stuck on an open reading frame (e.g. due to stable mRNA structures or inhibitory codons). Here, ubiquitination of ribosomal proteins serves as a signal for dissociation of the stuck ribosome by the RQC-trigger (RQT) complex. Subsequently the aberrant mRNA and the truncated nascent peptide are degraded and intact components such as ribosomal subunits or tRNAs can be recycled. Although this pathway has been studied in detail over the last years, the exact mechanism by which RQT leads to dissociation of stalled ribosomes remains unclear. This thesis aimed to elucidate the RQT-mediated dissociation mechanism by setting up an in vitro splitting system and subsequent cryo-EM analysis of the splitting reactions. To generate suitable substrates for the dissociation process, collisions were generated using known ribosome stalling sequences in a cell free in vitro translation system. Splitting assays showed that an in vitro ubiquitination step for collided ribosomes is crucial for splitting. Moreover, such assays revealed that efficient splitting is dependent on ATPase activity of the N-terminal helicase cassette of RQT component Slh1, on the presence of a neighboring ribosome and on availability of a 3’ mRNA overhang. Structural analysis of the ribosome-bound RQT complex divulged stable positioning of RQT on the lead ribosome of a collided ‘disome’ unit, as well as on 80S and 40S. The 80S-RQT complex was observed in two different states located in close proximity to the entry of the mRNA channel. Together with the observed requirement of available 3’mRNA and helicase activity of Slh1, this suggests that Slh1 can pull on the mRNA, leading to an initial model for ribosome dissociation. Ribosome stalling and subsequent collisions increase the probability of frameshifting and thus translation of an aberrant protein. Structural analysis of three collided ribosomes, so called trisomes, revealed the presence of multiprotein bridging factor (Mbf1), previously identified as a frameshift inhibitor. This small protein was found on the second and third colliding ribosomes, positioned between beak and body of the 40S subunit. Comparison with the human homolog EDF1, which was found to be recruited to emetine induced collisions, showed that those proteins bind in the exact same fashion. The position on the 40S subunit of the collided ribosomes suggests that both proteins interact directly with the mRNA to prevent frameshifting, probably in combination with preventing conformational changes required for translocation of the ribosome.   In conclusion, high resolution cryo-EM structures of both RQT and Mbf1 on ribosomes enabled detailed insights into the intricate quality control network targeting collisions in the cell. From this, molecular models for both a helicase driven dissociation mechanism by RQT and the frameshifting inhibition by Mbf1 could be derived. These results, together with the developed optimization strategies, provide the basis for future works, leading to a detailed understanding of these pathways

EDF1 coordinates cellular responses to ribosome collisions

Translation of aberrant mRNAs induces ribosomal collisions, thereby triggering pathways for mRNA and nascent peptide degradation and ribosomal rescue. Here we use sucrose gradient fractionation combined with quantitative proteomics to systematically identify proteins associated with collided ribosomes. This approach identified Endothelial differentiation-related factor 1 (EDF1) as a novel protein recruited to collided ribosomes during translational distress. Cryo-electron microscopic analyses of EDF1 and its yeast homolog Mbf1 revealed a conserved 40S ribosomal subunit binding site at the mRNA entry channel near the collision interface. EDF1 recruits the translational repressors GIGYF2 and EIF4E2 to collided ribosomes to initiate a negative-feedback loop that prevents new ribosomes from translating defective mRNAs. Further, EDF1 regulates an immediate-early transcriptional response to ribosomal collisions. Our results uncover mechanisms through which EDF1 coordinates multiple responses of the ribosome-mediated quality control pathway and provide novel insights into the intersection of ribosome-mediated quality control with global transcriptional regulation

Etravirine pharmacokinetics in HIV-infected pregnant women

__Background__ The study goal was to describe etravirine pharmacokinetics during pregnancy and postpartum in HIV-infected women. __Methods__ IMPAACT P1026s and PANNA are on-going, non-randomized, open-label, parallel-group, multi-center phase-IV prospective studies in HIV-infected pregnant women. Intensive steady-state 12-h pharmacokinetic profiles were performed from 2nd trimester through postpartum. Etravirine was measured at two labs using validated ultra performance liquid chromatography (detection limits: 0.020 and 0.026 mcg/mL). __Results__ Fifteen women took etravirine 200 mg twice-daily. Etravirine AUC0-12 was higher in the 3rd trimester compared to paired postpartum data by 34% (median 8.3 vs. 5.3 mcg*h/mL, p = 0.068). Etravirine apparent oral clearance was significantly lower in the 3rd trimester of pregnancy compared to paired postpartum data by 52% (median 24 vs. 38 L/h, p = 0.025). The median ratio of cord blood to maternal plasma concentration at delivery was 0.52 (range: 0.19-4.25) and no perinatal transmission occurred. __Conclusion__ Etravirine apparent oral clearance is reduced and exposure increased during the third trimester of pregnancy. Based on prior dose-ranging and safety data, no dose adjustment is necessary for maternal health but the effects of etravirine in utero are unknown. Maternal health and infant outcomes should be closely monitored until further infant safety data are available. __Clinical Trial registration:__ The IMPAACT protocol P1026s and PANNA study are registered at ClinicalTrials.gov under NCT00042289 and NCT00825929

Psychometric Properties and Correlates of Precarious Manhood Beliefs in 62 Nations

Precarious manhood beliefs portray manhood, relative to womanhood, as a social status that is hard to earn, easy to lose, and proven via public action. Here, we present cross-cultural data on a brief measure of precarious manhood beliefs (the Precarious Manhood Beliefs scale [PMB]) that covaries meaningfully with other cross-culturally validated gender ideologies and with country-level indices of gender equality and human development. Using data from university samples in 62 countries across 13 world regions (N = 33,417), we demonstrate: (1) the psychometric isomorphism of the PMB (i.e., its comparability in meaning and statistical properties across the individual and country levels); (2) the PMB’s distinctness from, and associations with, ambivalent sexism and ambivalence toward men; and (3) associations of the PMB with nation-level gender equality and human development. Findings are discussed in terms of their statistical and theoretical implications for understanding widely-held beliefs about the precariousness of the male gender role

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Grundlagen

„Mathe – kann ich“ – ein Satz, den die Mehrheit der Studierenden zu Beginn eines ingenieurwissenschaftlichen Studiengangs sicher nicht mit sich in Verbindung bringt. Die Buchreihe „Mathe – kann ich“ zielt darauf ab, dies schnell und einfach zu ändern. Der erste Band der Reihe befasst sich mit Grundlagenstoff. Er umfasst 14 Kapitel, von Arithmetik, Algebra, Polynome, Funktionen, Folgen über Ableitung und Integrationsrechnung bis hin zu Beweisen und Mengen. Jedes Kapitel führt in das Thema kurz ein, die verwendeten Begriffe werden definiert. Viele einfache Abbildungen tragen zur Veranschaulichung bei. Ausformulierte Lernziele, die jeweils mit „Ich kann …“ beginnen, helfen, sich die benötigte Mathematik zu erschließen. Sie folgen dem aktuell gültigem Curriculum der Europäischen Gesellschaft für die Ingenieur-Ausbildung (SEFI). Jedes Kapitel bietet zusätzlich eine Vielzahl an Aufgaben und schließlich ausführlichen Lösungen. Zu jeder Aufgabe gibt es eine Zeitangabe, die den Studierenden bei der Auswahl zum Anfang hilft. Die Aufgaben selbst sind unterschiedlich, teils auf Anwendung bezogen, teils zum Rechnen, teils zur Klärung der Begrifflichkeiten. Das Arbeiten mit Kann-Listen macht den eigenen Lernerfolg für Studierende sichtbar: einfach Abhaken! Darüber hinaus verbindet es das zu Lernende mit der Meta-Ebene des Stoffs, was für nachhaltiges Erinnern entscheidend ist. Der innovative didaktische Ansatz hat sich in der Praxis bewährt. Zusatzmaterialien zum Buch, wie computerunterstützte Lösungen zu den Aufgaben oder einige der Visualisierungen, werden auf plus.hanser-fachbuch.de bereitgestellt

Geometrie und Funktionen

Im Band 2 werden die Themen aus dem "Core Curriculum" der Europäischen Gesellschaft für Ingenieurausbildung (SEFI) fortgesetzt, in dem die wesentlichen Inhalte und Ziele der Mathematikausbildung für Ingenieure berücksichtigt werden: - Differentialrechnung, - Integralrechnung, - Differentialgleichungen, - Geometrie und Trigonometrie, - Diskrete Mathematik, - Vektoren, - Wahrscheinlichkeitsrechnung und Statistik. Jedes Kapitel führt in das Thema kurz ein, die verwendeten Begriffe werden definiert. Viele einfache Abbildungen tragen zur Veranschaulichung bei. Ausformulierte Lernziele, die jeweils mit "Ich kann ..." beginnen, helfen, sich die benötigte Mathematik zu erschließen. Das Arbeiten mit Kann-Listen macht den eigenen Lernerfolg für Studierende sichtbar: einfach Abhaken! Darüber hinaus verbindet es das zu Lernende mit der Meta-Ebene des Stoffs, was für nachhaltiges Erinnern entscheidend ist. Der innovative didaktische Ansatz hat sich in der Praxis bewährt. Jedes Kapitel bietet zusätzlich eine Vielzahl an Aufgaben und schließlich ausführlichen Lösungen. Zu jeder Aufgabe gibt es eine Zeitangabe, die den Studierenden bei der Auswahl zum Anfang hilft. Die Aufgaben selbst sind unterschiedlich, teils auf Anwendung bezogen, teils zum Rechnen, teils zur Klärung der Begrifflichkeiten