Structural basis of NINJ1-mediated plasma membrane rupture in cell death

Eukaryotic cells can undergo different forms of programmed cell death, many of which culminate in plasma membrane rupture as the defining terminal event; 1-7; . Plasma membrane rupture was long thought to be driven by osmotic pressure, but it has recently been shown to be in many cases an active process, mediated by the protein ninjurin-1; 8; (NINJ1). Here we resolve the structure of NINJ1 and the mechanism by which it ruptures membranes. Super-resolution microscopy reveals that NINJ1 clusters into structurally diverse assemblies in the membranes of dying cells, in particular large, filamentous assemblies with branched morphology. A cryo-electron microscopy structure of NINJ1 filaments shows a tightly packed fence-like array of transmembrane α-helices. Filament directionality and stability is defined by two amphipathic α-helices that interlink adjacent filament subunits. The NINJ1 filament features a hydrophilic side and a hydrophobic side, and molecular dynamics simulations show that it can stably cap membrane edges. The function of the resulting supramolecular arrangement was validated by site-directed mutagenesis. Our data thus suggest that, during lytic cell death, the extracellular α-helices of NINJ1 insert into the plasma membrane to polymerize NINJ1 monomers into amphipathic filaments that rupture the plasma membrane. The membrane protein NINJ1 is therefore an interactive component of the eukaryotic cell membrane that functions as an in-built breaking point in response to activation of cell death

Chromosome-Level Assemblies of the Pieris mannii Butterfly Genome Suggest Z-Origin and Rapid Evolution of the W Chromosome

The insect order Lepidoptera (butterflies and moths) represents the largest group of organisms with ZW/ZZ sex determination. While the origin of the Z chromosome predates the evolution of the Lepidoptera, the W chromosomes are considered younger, but their origin is debated. To shed light on the origin of the lepidopteran W, we here produce chromosome-level genome assemblies for the butterfly Pieris mannii and compare the sex chromosomes within and between P. mannii and its sister species Pieris rapae . Our analyses clearly indicate a common origin of the W chromosomes of the two Pieris species and reveal similarity between the Z and W in chromosome sequence and structure. This supports the view that the W in these species originates from Z-autosome fusion rather than from a redundant B chromosome. We further demonstrate the extremely rapid evolution of the W relative to the other chromosomes and argue that this may preclude reliable conclusions about the origins of W chromosomes based on comparisons among distantly related Lepidoptera. Finally, we find that sequence similarity between the Z and W chromosomes is greatest toward the chromosome ends, perhaps reflecting selection for the maintenance of recognition sites essential to chromosome segregation. Our study highlights the utility of long-read sequencing technology for illuminating chromosome evolution

Modelling the impact of interventions on imported, introduced and indigenous malaria infections in Zanzibar, Tanzania

Malaria cases can be classified as imported, introduced or indigenous cases. The World Health Organization's definition of malaria elimination requires an area to demonstrate that no new indigenous cases have occurred in the last three years. Here, we present a stochastic metapopulation model of malaria transmission that distinguishes between imported, introduced and indigenous cases, and can be used to test the impact of new interventions in a setting with low transmission and ongoing case importation. We use human movement and malaria prevalence data from Zanzibar, Tanzania, to parameterise the model. We test increasing the coverage of interventions such as reactive case detection; implementing new interventions including reactive drug administration and treatment of infected travellers; and consider the potential impact of a reduction in transmission on Zanzibar and mainland Tanzania. We find that the majority of new cases on both major islands of Zanzibar are indigenous cases, despite high case importation rates. Combinations of interventions that increase the number of infections treated through reactive case detection or reactive drug administration can lead to substantial decreases in malaria incidence, but for elimination within the next 40 years, transmission reduction in both Zanzibar and mainland Tanzania is necessary

Associations between environmental noise and myocardial infarction and stroke: Investigating the potential mediating effects of hypertension

BACKGROUND: We investigated whether hypertension may be a mediator in the pathway linking environmental noise exposure to incident MI and stroke. METHODS: Separately for MI and stroke, we built two population-based cohorts from linked health administrative data. Participants were residents of Montreal (Canada) between 2000 and 2014, aged 45 years and older who were free of hypertension and MI or stroke at time of entry. MI, stroke and hypertension were ascertained from validated case definitions. Residential long-term environmental noise exposure, expressed as the annual mean level acoustic equivalent 24 h (L(Aeq24h)), was estimated from a land use regression model. We performed mediation analysis based on the potential outcomes framework. We used a Cox proportional hazards model for the exposure-outcome model and a logistic regression for the exposure-mediator model. In sensitivity analysis we applied a marginal structural approach to estimate the natural direct and indirect effects. RESULTS: Each cohort included approximately 900 000 individuals, with 26 647 incident cases of MI and 16 656 incident cases of stroke. 36% of incident MI and 40% of incident stokes had previously developed hypertension. The estimated total effect per interquartile range increase (from 55.0 to 60.5 dB A) in the annual mean L(Aeq24h) was 1.073 (95% confidence interval (CI): 1.070-1.077) for both MI for stroke. We found no evidence of exposure-mediator interaction for both outcomes. The relationships between environmental noise and MI and stroke was not mediated by hypertension. CONCLUSIONS: This population-based cohort study suggests that the main route by which environmental noise exposure may cause MI or stroke is not through hypertension

Land-use-based freshwater sediment source fingerprinting using hydrogen isotope compositions of long-chain fatty acids

Rapidly changing land use patterns and frequent extreme weather events have resulted in an increased sediment flux to freshwater systems globally, highlighting the need for land-use-based sediment source fingerprinting. Application of variability in hydrogen isotope compositions (delta H-2 values) of vegetation-specific biomarkers from soils and sediments is relatively underexplored for land-use-based freshwater suspended sediment (SS) source fingerprinting, but has the potential to complement the information from routinely applied carbon isotope analysis and provide new insights. We analysed delta H-2 values of long-chain fatty acids (LCFAs) as vegetation-specific biomarkers in source soils and SS collected from the mixed land use Tarland catchment (74 km(2)) in NE Scotland, to identify stream SS sources and quantify their contributions to SS. Plant growth form was the primary control on source soils LCFAs (n-C26:0, n-C28:0, n-C30:0) delta H-2 variability, while the isotopic composition of source water had no significant control. Forest and heather moorland soils covered with dicotyledonous and gymnosperm species were differentiated from arable land and grasslands soils covered with monocotyledonous species. SS samples collected for fourteen months from the Tarland catchment with a nested sampling approach showed monocot-based land use (cereal crops, grassland) to be the major source of SS with 71 +/- 11% contribution on catchment-wide scale averaged throughout the sampling period. Storm events after a dry summer period and sustained high flow conditions in the streams during autumn and early winter suggested enhanced connectivity of more distant forest and heather moorland land uses covering relatively steep topography. This was shown by an increased contribution (44 +/- 8%) on catchment-wide scale from dicot and gymnosperm-based land uses during the corresponding period. Our study demonstrated successful application of vegetation-specificity in delta H-2 values of LCFAs for land-use-based freshwater SS source fingerprinting in a mesoscale catchment where delta H-2 values of LCFAs were primarily controlled by plant growth forms

Effect of compensatory evolution in the emergence and transmission of rifampicin-resistant Mycobacterium tuberculosis in Cape Town, South Africa: a genomic epidemiology study

BACKGROUND: Experimental data show that drug-resistance-conferring mutations are often associated with a decrease in the replicative fitness of bacteria in vitro, and that this fitness cost can be mitigated by compensatory mutations; however, the role of compensatory evolution in clinical settings is less clear. We assessed whether compensatory evolution was associated with increased transmission of rifampicin-resistant tuberculosis in Khayelitsha, Cape Town, South Africa. METHODS: We did a genomic epidemiological study by analysing available M tuberculosis isolates and their associated clinical data from individuals routinely diagnosed with rifampicin-resistant tuberculosis in primary care and hospitals in Khayelitsha, Cape Town, South Africa. Isolates were collected as part of a previous study. All individuals diagnosed with rifampicin-resistant tuberculosis and with linked biobanked specimens were included in this study. We applied whole-genome sequencing, Bayesian reconstruction of transmission trees, and phylogenetic multivariable regression analysis to identify individual and bacterial factors associated with the transmission of rifampicin-resistant M tuberculosis strains. FINDINGS: Between Jan 1, 2008, and Dec 31, 2017, 2161 individuals were diagnosed with multidrug-resistant or rifampicin-resistant tuberculosis in Khayelitsha, Cape Town, South Africa. Whole-genome sequences were available for 1168 (54%) unique individual M tuberculosis isolates. Compensatory evolution was associated with smear-positive pulmonary disease (adjusted odds ratio 1.49, 95% CI 1.08-2.06) and a higher number of drug-resistance-conferring mutations (incidence rate ratio 1.38, 95% CI 1.28-1.48). Compensatory evolution was also associated with increased transmission of rifampicin-resistant disease between individuals (adjusted odds ratio 1.55; 95% CI 1.13-2.12), independent of other patient and bacterial factors. INTERPRETATION: Our findings suggest that compensatory evolution enhances the in vivo fitness of drug-resistant M tuberculosis genotypes, both within and between patients, and that the in vitro replicative fitness of rifampicin-resistant M tuberculosis measured in the laboratory correlates with the bacterial fitness measured in clinical settings. These results emphasise the importance of enhancing surveillance and monitoring efforts to prevent the emergence of highly transmissible clones capable of rapidly accumulating new drug resistance mutations. This concern becomes especially crucial at present, because treatment regimens incorporating novel drugs are being implemented. FUNDING: Funding for this study was provided by a Swiss and South Africa joint research award (grant numbers 310030_188888, CRSII5_177163, and IZLSZ3_170834), the European Research Council (grant number 883582), and a Wellcome Trust fellowship (to HC; reference number 099818/Z/12/Z). ZS-D was funded through a PhD scholarship from the South African National Research Foundation and RMW was funded through the South African Medical Research Council

A tale of two coal regimes: An actor-oriented analysis of destabilisation and maintenance of coal regimes in Germany and Japan

Phasing out coal-fired electricity is an urgent global task, critical to efforts to mitigate climate change and air pollution. Despite the growth and increasing competitiveness of renewable energy, phase-out progress is slow, with coal-fired power even reaching an all-time global high in 2021. A key factor blocking or delaying this energy transition is the active resistance of coal regime actors with vested interests. However, there is still a lack of a systemic understanding of why some actors are more influential in shaping transition processes such as changes in policies or institutions. In this article, we present a comparative case study of the political struggle around the coal policy in Germany and Japan. We use the Endowment-Practice-Institutions (EPI) framework to analyse how actors try to destabilise or maintain the institutional arrangements underpinning the coal regimes in these countries and why some are more influential in shaping the policy outcomes. Our findings show that while actors' strategies are largely determined by the socio-political context they are embedded in, there are also certain patterns and common sequences of practices. These include commissioning a study, disseminating it through various networks and social media channels, mobilising the public through demonstrations, and engaging in advocacy with the aim of increasing the political bargaining power. Our analytical framework, which can be applied to various settings, helps to understand why certain policy outcomes occur amidst efforts to spur or stall energy transitions, and why regimes are destabilised in some case - but not in others

Malaria elimination in Zanzibar: where next?

In 2018, Zanzibar developed a national malaria strategic plan IV (2018-2023) to guide elimination of malaria by 2023. We assessed progress in the implementation of malaria activities as part of the end-term review of the strategic plan. The review was done between August and October 2022 following the WHO guideline to assess progress made towards malaria elimination, effectiveness of the health systems in delivering malaria case management; and malaria financing. A desk review examined available malaria data, annual work plans and implementation reports for evidence of implemented malaria activities. This was complemented by field visits to selected health facilities and communities by external experts, and interviews with health management teams and inhabitants to authenticate desk review findings. A steady increase in the annual parasite incidence (API) was observed in Zanzibar, from 2.7 (2017) to 3.6 (2021) cases per 1,000 population with marked heterogeneity between areas. However, about 68% of the detected malaria cases were imported into Zanzibar. Malaria case follow-up and investigation increased from <70% in 2017 to 94% and 96% respectively, in 2021. The review noted a 3.7-fold increase of the health allocation in the country's budget, from 31.7 million USD (2017/18) to 117.3 million USD (2022/23) but malaria allocation remained low (<1%). The varying transmission levels in the islands suggest a need for strategic re-orientation of the elimination attempts from a national-wide to a sub-national agenda. We recommend increasing malaria allocation from the health budget to ensure sustainability of malaria elimination interventions

Recent advances on social determinants of mental health: looking fast forward

The fields of psychiatry and mental health are increasingly recognizing the importance of social determinants of health (SDOH) and their impact on mental health outcomes. In this overview, the authors discuss the recent research, from the past 5 years, on advances made in SDOH work. SDOH frameworks and theories have expanded to include more social conditions, from traumas associated with immigration to psychosocial and community strengths, that impact mental health and well-being. Research has consistently shown the pervasive deleterious impacts of inequitable social conditions (e.g., food insecurity, housing instability) on minoritized populations' physical and mental health. Social systems of oppression (e.g., racism, minoritization) have also been shown to confer higher risk for psychiatric and mental disorders. The COVID-19 pandemic illuminated the inequitable impact of the social determinants of health outcomes. More efforts have been made in recent years to intervene on the social determinants through interventions at the individual, community, and policy levels, which have shown promise in improving mental health outcomes in marginalized populations. However, major gaps remain. Attention should be paid to developing guiding frameworks that incorporate equity and antiracism when designing SDOH interventions and improving methodological approaches for evaluating these interventions. In addition, structural-level and policy-level SDOH efforts are critical for making long-lasting and impactful advances toward mental health equity

Metal oxo clusters, from theory to innovation; Synthesis, mechanism & novel application in recyclable polymers

The world is currently facing major challenges such as climate change, which can be tackled by developing new materials that improve on current processes. One area showing great potential is the nanoparticle field which has been developing rapidly over the past 30 years. A nanoparticle can be thought of as a hybrid inorganic-organic object. The inorganic core dictates the physical properties such as e.g. luminescence, while the organic ligand shell provides colloidal stability and solubility. These materials are promising candidates for catalysis due to their high surface to volume ratio. However, size control remains one of the major challenges in this field. In the best case, these nanoparticles have a polydispersity of 5 %, which means that particles with an average size of 5 nm will also have particles with sizes of 4.75 and 5.25 nm. At the same time as the nanoparticle field, also metal oxo clusters were being reported in the literature. These materials are very similar to the previously mentioned nanoparticles, as they are also hybrid objects consisting of a core and a ligand shell. However, they are usually smaller and have the added advantage of being atomically precise. The latter means that their polydispersity is zero, making them excellent building blocks. However, these metal oxo clusters were mainly characterized using single crystal XRD to obtain structural data. This limited the possible synthesis to short and rigid ligands and introduced tedious and long crystallization processes. These limitations are the reason why this field has been dormant for the last 1-2 decades. Due to the clear advantage of having atomically precise building blocks, we sought to revive this field, by developing a new characterization toolbox that eliminates the need for crystallization. We first optimized the synthesis, after which the formation mechanism was studied. Using the knowledge gained from these projects, the clusters have been developed and used as tunable inorganic monomers in both free radical polymerizations and covalent adaptable networks. Firstly, the cluster synthesis was standardized as the reaction conditions in literature were quite divergent. We found that when a metal (Zr or Hf) alkoxide is reacted with 8 equivalents acetic acid, the M12-acetate cluster is consistently formed. After optimizing this for a short carboxylic acid, we performed the same reaction with longer carboxylic acids, similar to the nanoparticle field. After purification, we elucidated their structure via PDF measurements, thus eliminating the need for crystalline material. Fitting the data proved that clusters are formed regardless of the carboxylic acid used during synthesis. The dimerization of the clusters is controlled only by the sterical hindrance on the alpha-position of the carboxylic acid, not by it's length. If there is something different from a -CH2 on this position the monomeric M6 clusters will form, else the dimeric M12 clusters are formed. Through ligand exchange under the appropriate conditions (vacuum at 70 °C) it was possible to convert monomers into dimers and vice versa. The organic ligand shell was further characterized using NMR, FTIR and TGA. We found that, on top of the coordinated ligand shell, which display different binding modes (bridging & chelating), additional H-bonded ligands are present. Applying our toolbox for hafnium clusters we confirmed that the same conclusions are valid. Finally, we tested Zr12-oleate as catalysts for the esterification reaction between oleic acid and ethanol, since they can be seen as the smallest possible nanoparticle. 5 nm ZrO2 nanoparticles have been used successfully as esterification catalysts in the past. Interestingly, our clusters showed a 5-fold increase in reaction conversion due to their increased surface to volume ratio, creating a better, cheaper and more sustainable catalyst. Secondly, the formation mechanism was studied. Using NMR and FTIR we learned that the first 2 equivalents of carboxylic acid exchange with Zr(OPr)4. It appears that this exchange does not go towards completion but is an equilibrium. Only when the third equivalent is added a signal for free acid appears together with an ester signal. In situ EXAFS taught us, despite the large error, that the Zr complex after exchange with 1 equivalent of acid is most likely a dimer, while the 2 equivalent sample seems to fit a trimeric structure. By following the ester formation over time by NMR, while varying multiple reaction conditions, we found that the Zr concentration should be high in order to have sufficient ester formation. Increasing the length of the carboxylic acid and/or alkoxide or adding sterical hindrance has a strong negative effect on the ester formation. The Zr-Zr degeneracy, which is 4 in the final cluster, increases simultaneously with the ester formation. Finally, by combining our data a preliminary reaction mechanism was proposed where the initial ligand exchange is followed by a fast ester formation, after which a slow ester formation occurs and finally the Zr6 cluster is formed. Zr12-oleate and -linoleate clusters were used unsuccessfully as tunable inorganic monomers for radical polymer synthesis. Under our current conditions, reacting the clusters with AIBN, dicumyl peroxide or without initiator, no polymer networks were formed. It is possible that some low molecular weight polymers were formed but since our objective was to create a polymer network this was not investigated further. Instead, we used 10-undecenoic acid as a ligand, which has a terminal alkene. By reacting these clusters with 10 w% dicumyl peroxide solid polymer networks with excellent insoluble fractions were obtained. This result shows us that the alkene functionalities in oleic and linoleic acid are shielded by the remaining ligand tail, inhibiting successful polymerization. We then switched from alkene ligands to (meth-)acrylate ligands which are more reactive towards free radical polymerization. Using our previous knowledge, samples were synthesized with different amounts of reactive ligands on the surface. It was found that samples where the clusters contained 6 reactive ligands or more on the surface resulted in good insoluble fractions, indicative of a polymer network. When fewer reactive ligands were present on the surface, the insoluble fractions were too high. Whether the high insoluble fractions are due to low cluster functionalization or low cluster loading, is still unclear. Remarkably, the Tg did not change significantly despite the large variation in sample composition, not for the alkene-cluster networks nor the (meth-)acrylate-cluster networks. For the (meth-)acrylate capped clusters, polymer samples synthesized from mono-2-(acryloyloxy)ethyl succinate containing clusters show the most promising features. However, further research should be done to mechanically characterize these materials. Finally, the clusters were used as tunable monomers in covalent adaptable networks. The cluster surface was functionalized with different amounts of custom-made epoxy ligands, after which the clusters were reacted into a polymer network. It was found that the Tg ranges from approximately -5 °C to 40 °C and the insoluble fractions were good for almost all samples. The samples were able to relax stress very rapidly, but in a dissociative manner contrary to the intended associative transesterification. We postulate that a ligand exchange on the cluster core is responsible for the fast relaxation of the polymer networks. So far, no clear trend could be observed upon changing the polymer composition by adding co-monomer, different amounts of catalyst or different amount of epoxide ligands. However, DMA measurements showed that the addition of the clusters, even in small amounts, had a positive effect on the mechanical properties. So not only did we switch the reversible chemistry from a transesterification towards a ligand exchange mechanism, but we also improved the mechanical properties of the materials