Intermembrane space-localized TbTim15 is an essential subunit of the single mitochondrial inner membrane protein translocase of trypanosomes

All mitochondria import >95% of their proteins from the cytosol. This process is mediated by protein translocases in the mitochondrial membranes, whose subunits are generally highly conserved. Most eukaryotes have two inner membrane protein translocases (TIMs) that are specialized to import either presequence-containing or mitochondrial carrier proteins. In contrast, the parasitic protozoan Trypanosoma brucei has a single TIM complex consisting of one conserved and five unique subunits. Here, we identify candidates for new subunits of the TIM or the presequence translocase-associated motor (PAM) using a protein-protein interaction network of previously characterized TIM and PAM subunits. This analysis reveals that the trypanosomal TIM complex contains an additional trypanosomatid-specific subunit, designated TbTim15. TbTim15 is associated with the TIM complex, lacks transmembrane domains, and localizes to the intermembrane space. TbTim15 is essential for procyclic and bloodstream forms of trypanosomes. It contains two twin CX9C motifs and mediates import of both presequence-containing and mitochondrial carrier proteins. While the precise function of TbTim15 in mitochondrial protein import is unknown, our results are consistent with the notion that it may function as an import receptor for the non-canonical trypanosomal TIM complex.

Factors associated with return-to-work outcomes in inpatient rehabilitation - a systematic scoping review

Inpatient rehabilitation is common in Germany to improve return-to-work outcomes. The objective of this systematic scoping review was to identify factors associated with return-to-work outcomes in musculoskeletal, psychological and oncological health conditions to improve tailoring of rehabilitation therapies. A search was completed in Embase, Medline, PsycInfo and AMED until May 2023 for articles investigating inpatient rehabilitation including working-age patients with oncological, musculoskeletal, or psychological diseases using a quantitative design and reporting factors associated with return-to-work outcomes. Screening of all titles and abstracts was completed by one reviewer, full texts were read by two reviewers. Quality appraisal and data extraction was completed by two reviewers. Data was analysed using a narrative synthesis. Eighteen studies of moderate quality were included. The review identified a wide range of return-to-work parameters including employment status, work ability, sickness absence, retirement status and duration of employment since rehabilitation. In addition, 48 psychological, health- and work-related factors associated with return-to-work parameters were identified. Only one RCT investigated the relationship between a depression prevention intervention and a return-to-work outcome (work ability), which showed a significant effect. In addition to the depression prevention intervention, only the factor 'health literacy' could be considered modifiable and be addressed as part of an inpatient rehabilitation programme. Furthermore, gradual work reintegration programs and/or workplace interventions in addition to inpatient rehabilitation should be further explored to improve return-to-work outcomes.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

DNA segregation in mitochondria and beyond: insights from the trypanosomal tripartite attachment complex

The tripartite attachment complex (TAC) of the single mitochondrion of trypanosomes allows precise segregation of its single nucleoid mitochondrial genome during cytokinesis. It couples the segregation of the duplicated mitochondrial genome to the segregation of the basal bodies of the flagella. Here, we provide a model of the molecular architecture of the TAC that explains how its eight essential subunits connect the basal body, across the mitochondrial membranes, with the mitochondrial genome. We also discuss how the TAC subunits are imported into the mitochondrion and how they assemble to form a new TAC. Finally, we present a comparative analysis of the trypanosomal TAC with open and closed mitotic spindles, which reveals conserved concepts between these diverse DNA segregation systems.

A Msp1-containing complex removes orphaned proteins in the mitochondrial outer membrane of T. brucei

The AAA-ATPase Msp1 extracts mislocalised outer membrane proteins and thus contributes to mitochondrial proteostasis. Using pulldown experiments, we show that trypanosomal Msp1 localises to both glycosomes and the mitochondrial outer membrane, where it forms a complex with four outer membrane proteins. The trypanosome-specific pATOM36 mediates complex assembly of α-helically anchored mitochondrial outer membrane proteins such as protein translocase subunits. Inhibition of their assembly triggers a pathway that results in the proteasomal digestion of unassembled substrates. Using inducible single, double, and triple RNAi cell lines combined with proteomic analyses, we demonstrate that not only Msp1 but also the trypanosomal homolog of the AAA-ATPase VCP are implicated in this quality control pathway. Moreover, in the absence of VCP three out of the four Msp1-interacting mitochondrial proteins are required for efficient proteasomal digestion of pATOM36 substrates, suggesting they act in concert with Msp1. pATOM36 is a functional analog of the yeast mitochondrial import complex complex and possibly of human mitochondrial animal-specific carrier homolog 2, suggesting that similar mitochondrial quality control pathways linked to Msp1 might also exist in yeast and humans.

A ribosome-bound tRNA half stimulates mitochondrial translation during stress recovery in Trypanosoma brucei

The protozoan parasite Trypanosoma brucei and its disease-causing relatives are among the few organisms that barely regulate the transcription of protein-coding genes. Yet, alterations in its gene expression are essential to survive in different host environments. Recently, tRNA-derived RNAs have been implicated as regulators of many cellular processes within and beyond translation. Previously, we identified the tRNAThr-3'-half (AGU) as a ribosome-associated non-coding RNA able to enhance global translation. Here we report that the tRNAThr-3'-half is generated upon starvation inside the mitochondria. The tRNAThr-3'-half associates with mitochondrial ribosomes and stimulates translation during stress recovery, positively affecting mitochondrial activity and, consequently, cellular energy production capacity. Our results describe an organelle ribosome-associated ncRNA involved in translation regulation to boost the central hub of energy metabolism as an immediate stress recovery response.

The impact of daily mean air temperature on the proportion of time in hypoglycemia in 2,582 children and adolescents with type 1 diabetes - Is this association clinically relevant?

OBJECTIVES

To study the potential association between increases in daily mean air temperature and time below range (TBR <54 mg/dl) and time above range (TAR >250 mg/dl) in children and adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Individuals with type 1 diabetes <21 years with information on daily glucose profiles from the diabetes prospective follow-up study (DPV) were included (n = 2582). Further inclusion criteria were age at least 6 months at diabetes onset, diabetes duration for at least one year and treatment years 2020-2021. Mean daily air temperature and other meteorological parameters from 78 measurement stations in Germany were linked to the individual glucose sensor profile via the five-digit postcode areas of residency. We used multivariable repeated measures fractional logistic regression models with a compound symmetry covariance structure to study the association between a 1 °C increase in daily mean temperature and time in specific glucose ranges.

RESULTS

A 1 °C increase in daily mean temperature was associated with an acute (Odds Ratio (OR) 1.009 (95%-CI 1.007, 1.011)) and up to 7 days delayed (OR 1.003 (1.001, 1.005)) increase in TBR <54 mg/dl. Moreover, an acute decrease in TAR >250 mg/dl (OR 0.997 (0.996, 0.997)) was found.

CONCLUSIONS

Results of the DPV registry showed small, but statistically significant changes in TBR and TAR in association with a short-term temperature increase. Higher blood flow and faster insulin absorption might be one possible mechanism. In times of increasing temperature fluctuations meteorological impacts on time in range could become even more relevant.

45 years German Society of Biological Psychiatry (DGBP)

The foundation of a German Society of Biological Psychiatry (DGBP) was initiated at the Second World Congress of Biological Psychiatry of the WFSBP in Barcelona in 1978. Its mission was and is to promote interdisciplinary research on the biology of mental disorders and to translate results of biological research into clinical practice. During the presidency of Peter Falkai, its tasks were defined to improve the quality and support of biologically oriented research in Germany by the DFG (Deutsche Forschungsgemeinschaft; German Research Foundation), BMBF (Bundesministerium für Bildung und Forschung) and EU (European Union), to promote young researchers doing biologically oriented research, to improve on the diagnosis and therapy of mental disorders and to advise policy makers by taking part in legal processes. The DGBP has been a corporate member of the WFSBP from its beginning, became a cooperative member of the DGPPN (Deutsche Gesellschaft für Psychiatrie und Psychotherapie, Psychosomatik und Nervenheilkunde), later of the German Brain Council, and fostered relationships with other scientific societies. Over the past 45 years, more than twenty congresses were held in Germany and neighboring countries. Emerging from the pandemic, the DGBP is ready to continue its mission to promote interdisciplinary research on the biology of mental disorders with a focus on the development of young scientists and to translate results of biological research into clinical practice, with regard to pharmacotherapy in close cooperation with the Arbeitsgemeinschaft Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP). In this sense, this article also aims to stimulate the cooperation of the society with other national and international partners and to foster new relationships with young scientists and professionals interested in the aims and goals of the DGBP.

Corrigendum: Impact of climate change on non-communicable diseases due to increased ambient air pollution

[This corrects the article on p. 103-121 in vol. 8, PMID: 37799533.].

Observation of high-energy neutrinos from the Galactic plane

The origin of high-energy cosmic rays, atomic nuclei that continuously impact Earth's atmosphere, is unknown. Because of deflection by interstellar magnetic fields, cosmic rays produced within the Milky Way arrive at Earth from random directions. However, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. We searched for neutrino emission using machine learning techniques applied to 10 years of data from the IceCube Neutrino Observatory. By comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the Galactic plane at the 4.5σ level of significance. The signal is consistent with diffuse emission of neutrinos from the Milky Way but could also arise from a population of unresolved point sources.

The Mba1 homologue of Trypanosoma brucei is involved in the biogenesis of oxidative phosphorylation complexes

Consistent with other eukaryotes, the Trypanosoma brucei mitochondrial genome encodes mainly hydrophobic core subunits of the oxidative phosphorylation system. These proteins must be co-translationally inserted into the inner mitochondrial membrane and are synthesized by the highly unique trypanosomal mitoribosomes, which have a much higher protein to RNA ratio than any other ribosome. Here, we show that the trypanosomal orthologue of the mitoribosome receptor Mba1 (TbMba1) is essential for normal growth of procyclic trypanosomes but redundant in the bloodstream form, which lacks an oxidative phosphorylation system. Proteomic analyses of TbMba1-depleted mitochondria from procyclic cells revealed reduced levels of many components of the oxidative phosphorylation system, most of which belong to the cytochrome c oxidase (Cox) complex, three subunits of which are mitochondrially encoded. However, the integrity of the mitoribosome and its interaction with the inner membrane were not affected. Pull-down experiments showed that TbMba1 forms a dynamic interaction network that includes the trypanosomal Mdm38/Letm1 orthologue and a trypanosome-specific factor that stabilizes the CoxI and CoxII mRNAs. In summary, our study suggests that the function of Mba1 in the biogenesis of membrane subunits of OXPHOS complexes is conserved among yeast, mammals and trypanosomes, which belong to two eukaryotic supergroups.

MiniBooNE and MicroBooNE Combined Fit to a 3+1 Sterile Neutrino Scenario

This Letter presents the results from the MiniBooNE experiment within a full "3+1" scenario where one sterile neutrino is introduced to the three-active-neutrino picture. In addition to electron-neutrino appearance at short baselines, this scenario also allows for disappearance of the muon-neutrino and electron-neutrino fluxes in the Booster Neutrino Beam, which is shared by the MicroBooNE experiment. We present the 3+1 fit to the MiniBooNE electron-(anti)neutrino and muon-(anti)neutrino data alone and in combination with MicroBooNE electron-neutrino data. The best-fit parameters of the combined fit with the exclusive charged-current quasielastic analysis (inclusive analysis) are Δm^{2}=0.209  eV^{2}(0.033  eV^{2}), |U_{e4}|^{2}=0.016(0.500), |U_{μ4}|^{2}=0.500(0.500), and sin^{2}(2θ_{μe})=0.0316(1.0). Comparing the no-oscillation scenario to the 3+1 model, the data prefer the 3+1 model with a Δχ^{2}/d.o.f.=24.7/3(17.3/3), a 4.3σ(3.4σ) preference assuming the asymptotic approximation given by Wilks's theorem.

Evidence for neutrino emission from the nearby active galaxy NGC 1068

A supermassive black hole, obscured by cosmic dust, powers the nearby active galaxy NGC 1068. Neutrinos, which rarely interact with matter, could provide information on the galaxy’s active core. We searched for neutrino emission from astrophysical objects using data recorded with the IceCube neutrino detector between 2011 and 2020. The positions of 110 known gamma-ray sources were individually searched for neutrino detections above atmospheric and cosmic backgrounds. We found that NGC 1068 has an excess of 79 − 20 + 22 neutrinos at tera–electron volt energies, with a global significance of 4.2σ, which we interpret as associated with the active galaxy. The flux of high-energy neutrinos that we measured from NGC 1068 is more than an order of magnitude higher than the upper limit on emissions of tera–electron volt gamma rays from this source.

How can school-based interventions reduce health inequalities? Results from two reviews

Background

Even in young people the chances to grow up healthy are unequal, depending on their socioeconomic position (SEP). In order to reduce these health inequalities, the school is an important field of action for health promotion. However, the evidence is limited regarding interventions focusing on health inequalities. Thus, the aim of the current research is to investigate 1) which school-based interventions contribute to the reduction of socio-economic inequalities in health and health behaviour of children and adolescents and 2) how and under what conditions they are successful.

Methods

A systematic and a realist review were conducted. Some steps of the methodological approach were used synergistically for both reviews: development of the search strategy, selection of the databases (MEDLINE, SSCI, SCIE, DoPHER and TRoPHI) and some inclusion and exclusion criteria. The search covered the years 2000-2020. The screening and subsequent steps were applied specific to each review design.

Preliminary results

The search resulted in 10,524 hits of which 37 publications were included for the systematic review. Most of the interventions focused on nutrition (14), followed by mental health (8) and substance use (5). The results indicate that structural preventive interventions are more likely to reduce health inequalities compared to behavioral preventive interventions. For the Realist Review 7 studies were included. Intrapersonal, interpersonal, and institutional factors were extracted that are relevant for school-based interventions focusing on adolescents with low SEP.

Conclusions

The systematic review showed that school-based interventions are able to reduce health inequalities, but also to increase them. Structural preventive measures seem to be helpful in increasing health equity. The Realist review identified mechanisms of interventions which help to address students with lower SEP.

Key messages

• The evidence regarding interventions with focus on health inequalities is limited. We present two reviews analysing what interventions are needed and how and why they work.

• Structural preventive measures seem to be helpful in increasing health equity. Factors on the intrapersonal, interpersonal, and institutional level are important to address students with low SEP.

The situation of older Emergency Department patients. Results from a participatory observation study

Background

Elderly patients make up a substantial share of Emergency Department (ED) populations which will increase steadily in the coming decades. This poses a challenge for EDs that are not designed to care for multimorbid, frail, and care-dependent older patients. However, too little is known about the current situation of older ED patients and their specific needs. This study seeks to explore ED stays of older and geriatric patients from a patient-centered perspective.

Methods

Participatory observations of older patients’ ED stays were conducted in five different EDs in a central district of Berlin. This included the passive company of ED patients aged 65 years and older, as possible from admission to discharge or referral. The sampling strategy followed the logic of theoretical sampling. Observation notes were captured in a semi-structured protocol and subjected to systematic, comparative analysis based on the Grounded Theory approach.

Results

N = 71 cases of older ED patients were included. Patients’ mean age was 80 years and 52% were female. The total observation time amounted to 332 hours, the mean observation time was 4 hours and 40 minutes. Long waiting hours and uncertainty about the further course turned out to be burdensome for the patients. Other problems were the dependency of patients in their ability to satisfy basic needs such as toileting and hydration. Personnel mostly tried to address these needs but did not always have the capacities.

Conclusions

Like most health care institutions, EDs need to prepare for the consequences of aging societies. Older patients are more vulnerable to stressful situations such as ED stays and depend on more attention and nursing support. ED staff often lack the resources for this. Strategies are needed to adjust ED structures and processes to the specific needs of older patients. This includes the prevention of ED stays.

Key messages

Search for Unstable Sterile Neutrinos with the IceCube Neutrino Observatory

We present a search for an unstable sterile neutrino by looking for a resonant signal in eight years of atmospheric ν_{μ} data collected from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable) three-neutrino and the 3+1 sterile neutrino models are disfavored relative to the unstable sterile neutrino model, though with p values of 2.8% and 0.81%, respectively, we do not observe evidence for 3+1 neutrinos with neutrino decay. The best-fit parameters for the sterile neutrino with decay model from this study are Δm_{41}^{2}=6.7_{-2.5}^{+3.9}  eV^{2}, sin^{2}2θ_{24}=0.33_{-0.17}^{+0.20}, and g^{2}=2.5π±1.5π, where g is the decay-mediating coupling. The preferred regions of the 3+1+decay model from short-baseline oscillation searches are excluded at 90% C.L.

Monitoring autochthonous lung tumors induced by somatic CRISPR gene editing in mice using a secreted luciferase

Background

In vivo gene editing of somatic cells with CRISPR nucleases has facilitated the generation of autochthonous mouse tumors, which are initiated by genetic alterations relevant to the human disease and progress along a natural timeline as in patients. However, the long and variable, orthotopic tumor growth in inner organs requires sophisticated, time-consuming and resource-intensive imaging for longitudinal disease monitoring and impedes the use of autochthonous tumor models for preclinical studies.

Methods

To facilitate a more widespread use, we have generated a reporter mouse that expresses a Cre-inducible luciferase from Gaussia princeps (GLuc), which is secreted by cells in an energy-consuming process and can be measured quantitatively in the blood as a marker for the viable tumor load. In addition, we have developed a flexible, complementary toolkit to rapidly assemble recombinant adenoviruses (AVs) for delivering Cre recombinase together with CRISPR nucleases targeting cancer driver genes.

Results

We demonstrate that intratracheal infection of GLuc reporter mice with CRISPR-AVs efficiently induces lung tumors driven by mutations in the targeted cancer genes and simultaneously activates the GLuc transgene, resulting in GLuc secretion into the blood by the growing tumor. GLuc blood levels are easily and robustly quantified in small-volume blood samples with inexpensive equipment, enable tumor detection already several months before the humane study endpoint and precisely mirror the kinetics of tumor development specified by the inducing gene combination.

Conclusions

Our study establishes blood-based GLuc monitoring as an inexpensive, rapid, high-throughput and animal-friendly method to longitudinally monitor autochthonous tumor growth in preclinical studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01661-2.

Strong Constraints on Neutrino Nonstandard Interactions from TeV-Scale ν_{μ} Disappearance at IceCube

We report a search for nonstandard neutrino interactions (NSI) using eight years of TeV-scale atmospheric muon neutrino data from the IceCube Neutrino Observatory. By reconstructing incident energies and zenith angles for atmospheric neutrino events, this analysis presents unified confidence intervals for the NSI parameter ε_{μτ}. The best-fit value is consistent with no NSI at a p value of 25.2%. With a 90% confidence interval of -0.0041≤ε_{μτ}≤0.0031 along the real axis and similar strength in the complex plane, this result is the strongest constraint on any NSI parameter from any oscillation channel to date.

Mistargeting of aggregation prone mitochondrial proteins activates a nucleus-mediated posttranscriptional quality control pathway in trypanosomes

Mitochondrial protein import in the parasitic protozoan Trypanosoma brucei is mediated by the atypical outer membrane translocase, ATOM. It consists of seven subunits including ATOM69, the import receptor for hydrophobic proteins. Ablation of ATOM69, but not of any other subunit, triggers a unique quality control pathway resulting in the proteasomal degradation of non-imported mitochondrial proteins. The process requires a protein of unknown function, an E3 ubiquitin ligase and the ubiquitin-like protein (TbUbL1), which all are recruited to the mitochondrion upon ATOM69 depletion. TbUbL1 is a nuclear protein, a fraction of which is released to the cytosol upon triggering of the pathway. Nuclear release is essential as cytosolic TbUbL1 can bind mislocalised mitochondrial proteins and likely transfers them to the proteasome. Mitochondrial quality control has previously been studied in yeast and metazoans. Finding such a pathway in the highly diverged trypanosomes suggests such pathways are an obligate feature of all eukaryotes.

Mitochondria import most of their proteins posttranslationally. Here, Dewar et al. characterize the mitochondrial quality control mechanism of Trypanosoma brucei. Through proteomics and functional studies, they show that only ablation of ATOM69, one of the seven subunits of its mitochondrial protein translocase, triggers a unique quality control pathway resulting in TbUbL1 release from the nucleus and subsequent proteasomal degradation of non-imported mitochondrial proteins.

p166 links membrane and intramitochondrial modules of the trypanosomal tripartite attachment complex

The protist parasite Trypanosoma brucei has a single mitochondrion with a single unit genome termed kinetoplast DNA (kDNA). Faithfull segregation of replicated kDNA is ensured by a complicated structure termed tripartite attachment complex (TAC). The TAC physically links the basal body of the flagellum with the kDNA spanning the two mitochondrial membranes. Here, we characterized p166 as the only known TAC subunit that is anchored in the inner membrane. Its C-terminal transmembrane domain separates the protein into a large N-terminal region that interacts with the kDNA-localized TAC102 and a 34 aa C-tail that binds to the intermembrane space-exposed loop of the integral outer membrane protein TAC60. Whereas the outer membrane region requires four essential subunits for proper TAC function, the inner membrane integral p166, via its interaction with TAC60 and TAC102, would theoretically suffice to bridge the distance between the OM and the kDNA. Surprisingly, non-functional p166 lacking the C-terminal 34 aa still localizes to the TAC region. This suggests the existence of additional TAC-associated proteins which loosely bind to non-functional p166 lacking the C-terminal 34 aa and keep it at the TAC. However, binding of full length p166 to these TAC-associated proteins alone would not be sufficient to withstand the mechanical load imposed by the segregating basal bodies.

Evolution and diversification of mitochondrial protein import systems

More than 95% of mitochondrial proteins are encoded in the nucleus, synthesised in the cytosol and imported into the organelle. The evolution of mitochondrial protein import systems was therefore a prerequisite for the conversion of the α-proteobacterial mitochondrial ancestor into an organelle. Here, I review that the origin of the mitochondrial outer membrane import receptors can best be understood by convergent evolution. Subsequently, I discuss an evolutionary scenario that was proposed to explain the diversification of the inner membrane carrier protein translocases between yeast and mammals. Finally, I illustrate a scenario that can explain how the two specialised inner membrane protein translocase complexes found in most eukaryotes were reduced to a single multifunctional one in trypanosomes.

Characterization of a highly diverged mitochondrial ATP synthase Fo subunit in Trypanosoma brucei

The mitochondrial F₁F_o ATP synthase of the parasite Trypanosoma brucei has been previously studied in detail. This unusual enzyme switches direction in functionality during the life cycle of the parasite, acting as an ATP synthase in the insect stages, and as an ATPase to generate mitochondrial membrane potential in the mammalian bloodstream stages. Whereas the trypanosome F₁ moiety is relatively highly conserved in structure and composition, the F_o subcomplex and the peripheral stalk have been shown to be more variable. Interestingly, a core subunit of the latter, the normally conserved subunit b, has been resistant to identification by sequence alignment or biochemical methods. Here, we identified a 17 kDa mitochondrial protein of the inner membrane, Tb927.8.3070, that is essential for normal growth, efficient oxidative phosphorylation, and membrane potential maintenance. Pull-down experiments and native PAGE analysis indicated that the protein is both associated with the F₁F_o ATP synthase and integral to its assembly. In addition, its knockdown reduced the levels of F_o subunits, but not those of F₁, and disturbed the cell cycle. Finally, analysis of structural homology using the HHpred algorithm showed that this protein has structural similarities to F_o subunit b of other species, indicating that this subunit may be a highly diverged form of the elusive subunit b.

Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data

We present an all-sky 90% confidence level upper limit on the cosmic flux of relativistic magnetic monopoles using 2886 days of IceCube data. The analysis was optimized for monopole speeds between 0.750c and 0.995c, without any explicit restriction on the monopole mass. We constrain the flux of relativistic cosmic magnetic monopoles to a level below 2.0×10^{-19}  cm^{-2} s^{-1} sr^{-1} over the majority of the targeted speed range. This result constitutes the most strict upper limit to date for magnetic monopoles with β≳0.8 and up to β∼0.995 and fills the gap between existing limits on the cosmic flux of nonrelativistic and ultrarelativistic magnetic monopoles.

Mitoribosomal small subunit maturation involves formation of initiation-like complexes

Mitochondrial ribosomes (mitoribosomes) play a central role in synthesizing mitochondrial inner membrane proteins responsible for oxidative phosphorylation. Although mitoribosomes from different organisms exhibit considerable structural variations, recent insights into mitoribosome assembly suggest that mitoribosome maturation follows common principles and involves a number of conserved assembly factors. To investigate the steps involved in the assembly of the mitoribosomal small subunit (mt-SSU) we determined the cryoelectron microscopy structures of middle and late assembly intermediates of the Trypanosoma brucei mitochondrial small subunit (mt-SSU) at 3.6- and 3.7-Å resolution, respectively. We identified five additional assembly factors that together with the mitochondrial initiation factor 2 (mt-IF-2) specifically interact with functionally important regions of the rRNA, including the decoding center, thereby preventing premature mRNA or large subunit binding. Structural comparison of assembly intermediates with mature mt-SSU combined with RNAi experiments suggests a noncanonical role of mt-IF-2 and a stepwise assembly process, where modular exchange of ribosomal proteins and assembly factors together with mt-IF-2 ensure proper 9S rRNA folding and protein maturation during the final steps of assembly.

Implementing Kolb´s Experiential Learning Cycle by Linking Real Experience, Case-Based Discussion and Simulation

BACKGROUND

Background: To prepare medical students for their future, they must become acquainted with clinical practice, for example by means of simulations, clerkships and discussing patient cases. By connecting these different approaches, according to Kolb´s experiential learning cycle, the learning effect can be strengthened.

METHODOLOGY

In the development of a didactical program for students who are being prepared for their role as general practitioners, we have adopted a new didactic approach, in which educational formats are interlinked, according to Kolb´s experiential learning cycle. The content of these courses is determined by the Entrustable Professional Activities (EPAs) for the clerkship in family medicine, combined with the most common chief complaints of patients in the GP's practice. In 2019, the first course was implemented at the Technical University of Munich, Germany, with 6 medical students. A first seminar discusses patients who the students have seen for themselves during their clerkship in family medicine. In addition, matching theory is discussed and skills are practiced. In the next seminar, students apply the acquired knowledge and skills in scenarios with standardized patients. Students evaluated the courses as positive. The evaluations show they find discussing personally experienced patient cases and the opportunity to practice very valuable.

CONCLUSIONS

A course design according to Kolb's Experiential learning cycle, which integrates experience, theory and simulation, is a valuable addition to existing forms of teaching in medical education. Students appreciated both discussing personally experienced patient cases and the opportunity to re-practice similar cases in a simulated environment. To gain more insight into the learning effects, it is recommended to further explore this approach in a different context.

DNA identification of species of the Anopheles maculipennis complex and first record of An. daciae in Belgium

The present study aimed at identifying the members of the Anopheles maculipennis complex (Diptera: Culicidae) occurring in Belgium. Therefore, the second internal transcribed spacer of nuclear ribosomal DNA (ITS2) and the mitochondrial cytochrome oxidase subunit I (COI) loci were sequenced in 175 and 111 specimens, respectively, collected between 2007 and 2019. In parallel, the suitability of two species-diagnostic PCR-RFLP assays was tested. The identified specimens included: An. maculipennis s.s. (N = 105), An. daciae (N = 62), An. atroparvus (N = 6) and An. messeae (N = 2). Each species was characterized by unique ITS2 haplotypes, whereas COI only supported the monophyly of An. atroparvus, a historical malaria vector in Belgium. Species identification results were further supported by unique PCR-RFLP banding patterns. We report for the first time An. daciae in Belgium, where it was found to co-occur with An. maculipennis s.s. The latter was the most prevalent in the collection studied (60%) and appears to have the widest distribution in Belgium. As in other studies, An. daciae and An. messeae appeared the most closely related species, up to the point that their species status remains debatable, while their ecological differences, including vector competences, need further study.

Invasive populations of Spiraea tomentosa (Rosaceae) are genetically diverse but decline during succession in forest habitats

Population genetic and ecological data may help to control invasive plants, which are considered a major threat to natural habitats. In contrast to expected bottleneck events, genetic diversity of such invasive populations may be high due to extensive propagule pressure or admixture. The ecological impact of invasive species has been broadly evaluated in the field; however, long-term studies on the fate of invasive plants are scarce. We analysed genetic diversity and structure in invasive Spiraea tomentosa populations in eastern Germany and western Poland using Amplified Fragment Length Polymorphism. Potential hybridization between co-occurring diploid Sp. tomentosa and tetraploid Sp. douglasii was investigated using Flow Cytometry. The genetic analyses were complemented by data from a 13-year vegetation study in an area invaded by these Spiraea species. We found no evidence for hybridization between Spiraea species. In populations of Sp. tomentosa both genetic diversity (He = 0.26) and genetic structure (ΦPT = 0.27) were high and comparable to other outcrossing woody plants. Low levels of clonality, presence of seedlings and new patches in sites that had been colonized over the last 13 years imply that populations spread via sexual reproduction. In all habitat types, native species diversity declined following Sp. tomentosa invasion. However, detailed aerial mapping of a forest reserve with ongoing succession revealed that Spiraea spp. populations have declined over a 10-year period. Despite its potential for dispersal and negative effects on native plant communities, invasive Spiraea populations may be controlled by increasing canopy cover in forest habitats.

Minimal peptide length required to span the mitochondrial protein translocases in Trypanosoma brucei

Mitochondrial protein import depends on heterooligomeric translocases in the outer and inner membranes. Using import substrates consisting of various lengths of the N-terminal part of mitochondrial dihydrolipoamide dehydrogenase (LDH) fused to dihydrofolate reductase we present an in vivo analysis showing that in Trypanosoma brucei at least 96 aa of mature LDH are required to efficiently produce an import intermediate that spans both translocases. This is different to yeast, where around 50 aa are sufficient to achieve the same task and likely reflects the different arrangement and architecture of the trypanosomal mitochondrial translocases. Furthermore, we show that formation of the stuck import intermediate leads to a strong growth inhibition suggesting that, depending on the length of the LDH, the import channels in the translocases are quantitatively blocked.

The burden of heat-related mortality attributable to recent human-induced climate change

Climate change affects human health; however, there have been no large-scale, systematic efforts to quantify the heat-related human health impacts that have already occurred due to climate change. Here, we use empirical data from 732 locations in 43 countries to estimate the mortality burdens associated with the additional heat exposure that has resulted from recent human-induced warming, during the period 1991-2018. Across all study countries, we find that 37.0% (range 20.5-76.3%) of warm-season heat-related deaths can be attributed to anthropogenic climate change and that increased mortality is evident on every continent. Burdens varied geographically but were of the order of dozens to hundreds of deaths per year in many locations. Our findings support the urgent need for more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change.

Depletion of Numb and Numblike in Murine Lung Epithelial Cells Ameliorates Bleomycin-Induced Lung Fibrosis by Inhibiting the β-Catenin Signaling Pathway

Idiopathic pulmonary fibrosis (IPF) represents the most aggressive form of pulmonary fibrosis (PF) and is a highly debilitating disorder with a poorly understood etiology. The lung epithelium seems to play a critical role in the initiation and progression of the disease. A repeated injury of lung epithelial cells prompts type II alveolar cells to secrete pro-fibrotic cytokines, which induces differentiation of resident mesenchymal stem cells into myofibroblasts, thus promoting aberrant deposition of extracellular matrix (ECM) and formation of fibrotic lesions. Reactivation of developmental pathways such as the Wnt-β-catenin signaling cascade in lung epithelial cells plays a critical role in this process, but the underlying mechanisms are still enigmatic. Here, we demonstrate that the membrane-associated protein NUMB is required for pathological activation of β-catenin signaling in lung epithelial cells following bleomycin-induced injury. Importantly, depletion of Numb and Numblike reduces accumulation of fibrotic lesions, preserves lung functions, and increases survival rates after bleomycin treatment of mice. Mechanistically, we demonstrate that NUMB interacts with casein kinase 2 (CK2) and relies on CK2 to activate β-catenin signaling. We propose that pharmacological inhibition of NUMB signaling may represent an effective strategy for the development of novel therapeutic approaches against PF.

Classification of endonasal HHT lesions using digital microscopy

BACKGROUND

Recurrent spontaneous epistaxis is the most common clinical manifestation and the most debilitating symptom in hereditary haemorrhagic telangiectasia (HHT) patients. To this date, there exist only a classification of HHT patients by different genetic mutations. There is no standard classification for the mucocutaneous endonasal manifestations of HHT. The aim of the present study was to document the variety of endonasal HHT lesions using digital microscopy and to propose a clinical classification.

METHODS

We recorded the endonasal HHT lesions of 28 patients using a digital microscope. We reconstructed the 3D images und videos recorded by digital microscope afterwards and classified the endonasal lesions of HHT in two classes: Grade A, presence of only flat telangiectasias in the mucosa level and Grade B, (additional) presence of raised berry or wart-like telangiectasia spots. We investigated also Haemoglobin level by routine laboratory procedures, plasma VEGF level by ELISA, Severity of epistaxis by epistaxis severity score (ESS) and quality of life by a linear visual analogue scale (VAS).

RESULTS

We found a higher quality of life and a lower severity of epistaxis in Grade A patients in comparison to Grade B patients. No difference in plasma VEGF level and in Haemoglobin between Grad A patients and Grade B patients could be detected. Plasma VEGF levels showed no gender specific differences. It could also not be correlated to the extranasal manifestation.

CONCLUSION

The classification for endonasal manifestation of HHT proposed in this study indicates severity of epistaxis und quality of life. Digital microscopy with the ability of 3D reconstruction of images presents a useful tool for such classifications. The classification of endonasal HHT lesions using digital microscopy allows to evaluate the dynamic of HHT lesions in the course of time independent of examiner. This allows also to evaluate the efficacy of the different treatment modalities by dynamic of HHT lesions. Moreover digital microscopy is very beneficial in academic teaching of rare diseases.

tRNA 3' shortening by LCCR4 as a response to stress in Trypanosoma brucei

Sensing of environmental cues is crucial for cell survival. To adapt to changes in their surroundings cells need to tightly control the repertoire of genes expressed at any time. Regulation of translation is key, especially in organisms in which transcription is hardly controlled, like Trypanosoma brucei. In this study, we describe the shortening of the bulk of the cellular tRNAs during stress at the expense of the conserved 3' CCA-tail. This tRNA shortening is specific for nutritional stress and renders tRNAs unsuitable substrates for translation. We uncovered the nuclease LCCR4 (Tb927.4.2430), a homologue of the conserved deadenylase Ccr4, as being responsible for tRNA trimming. Once optimal growth conditions are restored tRNAs are rapidly repaired by the trypanosome tRNA nucleotidyltransferase thus rendering the recycled tRNAs amenable for translation. This mechanism represents a fast and efficient way to repress translation during stress, allowing quick reactivation with a low energy input.

Cardiomyocytes-specific deletion of monoamine oxidase B reduces irreversible myocardial ischemia/reperfusion injury

Monoamine oxidase B (MAO-B), a protein localized at the outer mitochondrial membrane, catalyzes the oxidative deamination of biogenic amines thereby producing reactive oxygen species (ROS). Increased ROS formation contributes to myocardial ischemia/reperfusion (I/R); however, the importance of different ROS producing enzymes for increased I/R-induced ROS formation and the subsequent I/R injury is still a matter of debate. Here we describe the first cardiomyocytes-specific MAO-B knockout mouse and test the hypothesis that lack of cardiomyocyte MAO-B protects the heart from I/R injury. A cardiac-specific and tamoxifen-inducible MAO-B knockout mouse (MAO-B KO) was generated using the Cre/lox system; Cre-negative MAO-B^fl/fl littermates served as controls (WT). Lack of MAO-B was verified by Western blot and immunohistochemistry. Cardiac function of MAO-B KO and WT was analyzed by echocardiography, quantification of mitochondrial ROS production, and measurement of myocardial infarct size (in % of ventricle) in hearts exposed to global I/R using the Langendorff technique. MAO-B protein expression was significantly down-regulated in MAO-B KO mice after two weeks of tamoxifen feeding followed by ten weeks of feeding with normal chow. ROS formation stimulated by the MAO-B-specific substrate β-phenylethylamin (PEA; 250 μM) was significantly lower in mitochondria isolated from MAO-B KO compared to WT hearts (WT 4.5 ± 0.8 a. u.; MAO-B KO 1.2 ± 0.3 a. u.). Echocardiography revealed no significant differences in LV dimensions as well as ejection fraction (EF) between WT and MAO-B KO mice (EF: WT 67.3 ± 8.8%; MAO-B KO 67.7 ± 6.5%). After I/R, infarct size was significantly lower in MAO-B KO hearts (WT 69.3 ± 15.1%; MAO-B KO 46.8 ± 12.0%). CONCLUSION: Lack of cardiomyocytes-specific MAO-B reduces infarct size suggesting that MAO-B activity contributes to acute reperfusion injury.