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Although social position plays a pivotal role in cognitive aging, most dementia prevention strategies and risk prediction models continue to emphasize biomedical and genetic factors (particularly APOE status). This disconnect raises critical questions about how social environments may shape the effect of genetic risk on dementia. We examined how APOE alleles interact with social adversity to determine dementia risk. We conducted an observational analysis using two large cohort studies-the Health and Retirement Study (HRS) and the English Longitudinal Study of Ageing (ELSA)-including individuals aged 55 years or older without dementia at baseline. A social adversity index was constructed based on the five domains of social determinants of health outlined in the Healthy People 2030 framework: education access, economic stability, healthcare quality, neighborhood environment, and social context. Participants were classified as having low (APOE-ε2), intermediate (APOE-ε3/ε3), or high (APOE-ε4) genetic risk of dementia. Dementia was ascertained via clinical diagnosis, cognitive testing, or validated caregiver report. Cox proportional hazards models were used in each cohort, and estimates were pooled using random-effects adjusting for covariates. A total of 9,849 participants (HRS = 5,797; ELSA = 4,052) were followed for up to 12 years. Genetic effects were most pronounced among individuals with social advantage (reference: APOE-ε3/ε3 with social advantage; APOE-ε2 HR = 0.67, 95%CI = 0.48-0.93; APOE-ε4 HR = 1.68, 95%CI = 1.37-2.06). In contrast, those experiencing high social adversity had elevated dementia risk regardless of genotype (reference: APOE-ε3/ε3 with social advantage; APOE-ε2 HR = 3.26, 95%CI = 2.06-5.16; APOE-ε3/ε3 HR = 3.12, 95%CI = 2.47-3.95; APOE-ε4 HR = 3.21, 95%CI = 2.34-4.41). Notably, individuals with high genetic risk but social advantage had a lower dementia risk than those with low genetic risk but high social adversity. The influence of genetic risk on dementia appears shaped by social position. Addressing social adversity may reduce dementia risk across genotypes and enhance equity in dementia prevention strategies.

Massive galaxies in the early Universe host supermassive black holes at their centers. When material falls toward the black hole, it releases energy and is observed as a quasar. Astronomers found a population of powerful distant quasars that are obscured by dust, but it has been unclear how they are formed. Díaz-Santos et al. observed the dust-obscured quasar WISE J224607.56-052634.9 at submillimeter wavelengths, finding three small companion galaxies connected to the quasar by bridges of gas and dust. They inferred that galaxy mergers can provide both the raw material to power a quasar and large quantities of dust to obscure it. Science , this issue p. 1034 Galaxy mergers can provide the raw materials to drive powerful dust-observed quasars in the early Universe. Galaxy mergers and gas accretion from the cosmic web drove the growth of galaxies and their central black holes at early epochs. We report spectroscopic imaging of a multiple merger event in the most luminous known galaxy, WISE J224607.56−052634.9 (W2246−0526), a dust-obscured quasar at redshift 4.6, 1.3 billion years after the Big Bang. Far-infrared dust continuum observations show three galaxy companions around W2246−0526 with disturbed morphologies, connected by streams of dust likely produced by the dynamical interaction. The detection of tidal dusty bridges shows that W2246−0526 is accreting its neighbors, suggesting that merger activity may be a dominant mechanism through which the most luminous galaxies simultaneously obscure and feed their central supermassive black holes.

Galaxies grow by forming stars from cold molecular gas. The rate at which they do so is limited by various feedback processes (such as supernovae or stellar winds) that heat and/or eject gas from the host galaxy. Spilker et al. used submillimeter observations to discover an outflow of molecular gas from a galaxy in the early Universe, a period of vigorous star formation. Modeling the outflow revealed that the mass of gas being ejected is similar to that being turned into stars. The results will help determine how quickly galaxies formed after the Big Bang. Science , this issue p. 1016 A galaxy in the early Universe is driving an outflow of molecular gas, a sign of feedback regulating star formation. Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow launched from a dust-rich star-forming galaxy at redshift 5.3, 1 billion years after the Big Bang. The outflow reaches velocities up to 800 kilometers per second relative to the galaxy, is resolved into multiple clumps, and carries mass at a rate within a factor of 2 of the star formation rate. Our results show that molecular outflows can remove a large fraction of the gas available for star formation from galaxies at high redshift.

Plastic debris has been recognised as a potential stressor for Antarctic marine organisms. In this study, the effects of surface charged polystyrene nanoparticles (PS NPs) on the immune cells (coelomocytes) of the Antarctic sea urchin Sterechinus neumayeri were assessed through in vitro short-term cultures. The behaviour of anionic carboxylated (PS-COOH) and cationic amino-modified (PS-NH2) NPs in filtered natural sea water (NSW) from King George Island (South Shetland Islands) was characterised by dynamic light scattering. Cellular morphology, NP uptake, phagocytic capacity and gene expression were evaluated after 6 and 24 h of exposure to 1 and 5 µg mL−1 PS NPs. Secondary characterisation showed an initial good dispersion of PS NPs in NSW, followed by nano-scale aggregation after 24 h. Both PS NPs affected cellular phagocytosis and generated an inflammatory response against oxidative stress and apoptosis at the molecular level. Fluorescently labelled PS-COOH aggregates were internalised by phagocytes and associated to the modulation of genes related to external challenges, antioxidant responses and cell protection against stress and apoptosis. Exposure to PS-NH2 caused a strong decrease in phagocytic capacity and the formation of cellular debris at 5 µg mL−1 after 24 h, but low gene modulation, suggesting a threshold in coelomocytes defence ability against PS-NH2. This study represents the first attempt to assess the impact of nanoplastics on Antarctic marine organisms. Our findings demonstrate that PS NPs with different surface charges constitute a challenge for S. neumayeri immune cells.

Over the past decades, rest-frame ultraviolet (UV) observations have provided large samples of UV luminous galaxies at redshift ( z ) greater than 6 (refs. 1 – 3 ), during the so-called epoch of reionization. While a few of these UV-identified galaxies revealed substantial dust reservoirs 4 – 7 , very heavily dust-obscured sources at these early times have remained elusive. They are limited to a rare population of extreme starburst galaxies 8 – 12 and companions of rare quasars 13 , 14 . These studies conclude that the contribution of dust-obscured galaxies to the cosmic star formation rate density at z  > 6 is sub-dominant. Recent ALMA and Spitzer observations have identified a more abundant, less extreme population of obscured galaxies at z  = 3−6 (refs. 15 , 16 ). However, this population has not been confirmed in the reionization epoch so far. Here, we report the discovery of two dust-obscured star-forming galaxies at z  = 6.6813 ± 0.0005 and z  = 7.3521 ± 0.0005. These objects are not detected in existing rest-frame UV data and were discovered only through their far-infrared [C  ii ] lines and dust continuum emission as companions to typical UV-luminous galaxies at the same redshift. The two galaxies exhibit lower infrared luminosities and star-formation rates than extreme starbursts, in line with typical star-forming galaxies at z  ≈ 7. This population of heavily dust-obscured galaxies appears to contribute 10–25% to the z  > 6 cosmic star formation rate density. Two serendipitously detected dust-obscured galaxies are reported at z = 6.7 and 7.4, with estimates that such galaxies provide an additional 10–25% contribution to the total star formation rate density at z > 6.

Two extremely massive galaxies are seen 800 million years after the Big Bang, showing the rapid growth of early structure and marking the most massive halo known in that era. A massive galaxy in the early Universe The most massive galaxies in the early Universe were very rare objects and observing them during their growing stage is a challenge. Daniel Marrone and collaborators report observations of one of them less than 800 million years after the Universe began, which high-resolution imaging reveals to in fact be a closely interacting pair of galaxies. The larger one is forming stars at a rate of 2,900 solar masses per year, and contains 270 billion solar masses of gas. The rapid star formation was probably triggered by the interaction with its close companion, whose properties are closer to those of galaxies observed in the nearby Universe. According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field 1 , 2 , 3 . Observing these structures during their period of active growth and assembly—the first few hundred million years of the Universe—is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far 4 , 5 . Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey 6 . High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe 7 . These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.

Massive galaxy clusters have been found that date to times as early as three billion years after the Big Bang, containing stars that formed at even earlier epochs1,2,3. The high-redshift progenitors of these galaxy clusters—termed ‘protoclusters’—can be identified in cosmological simulations that have the highest overdensities (greater-than-average densities) of dark matter4,5,6. Protoclusters are expected to contain extremely massive galaxies that can be observed as luminous starbursts7. However, recent detections of possible protoclusters hosting such starbursts8,9,10,11 do not support the kind of rapid cluster-core formation expected from simulations12: the structures observed contain only a handful of starbursting galaxies spread throughout a broad region, with poor evidence for eventual collapse into a protocluster. Here we report observations of carbon monoxide and ionized carbon emission from the source SPT2349-56. We find that this source consists of at least 14 gas-rich galaxies, all lying at redshifts of 4.31. We demonstrate that each of these galaxies is forming stars between 50 and 1,000 times more quickly than our own Milky Way, and that all are located within a projected region that is only around 130 kiloparsecs in diameter. This galaxy surface density is more than ten times the average blank-field value (integrated over all redshifts), and more than 1,000 times the average field volume density. The velocity dispersion (approximately 410 kilometres per second) of these galaxies and the enormous gas and star-formation densities suggest that this system represents the core of a cluster of galaxies that was already at an advanced stage of formation when the Universe was only 1.4 billion years old. A comparison with other known protoclusters at high redshifts shows that SPT2349-56 could be building one of the most massive structures in the Universe today.

INTRODUCTION This study aimed to compare the willingness to use Alzheimer's disease (AD) predictive–diagnostic procedures between Mapuche (Indigenous) and non‐Indigenous older adults in Chile. METHODS We conducted a cross‐sectional study including Mapuche (n = 167) and non‐Indigenous (n = 248) older adults. Willingness to undergo five predictive–diagnostic procedures (AD risk test, neuropsychological assessment, blood test, brain imaging, and cerebrospinal fluid analysis) was evaluated. Logistic regression models were used to identify factors associated with willingness. RESULTS Overall willingness was high, except for cerebrospinal fluid testing (39.1%). In fully adjusted models, Mapuche participants were significantly less willing to undergo neuropsychological assessment (77.8% vs. 92.3%), blood testing (68.3% vs. 89.9%), and brain imaging (73.1% vs. 84.3%). Key determinants of willingness varied by ethnic group and included age, sex, AD‐related worry, social determinants, and number of dementia risk factors. DISCUSSION Despite high overall willingness, ethnic identity and psychosocial factors significantly influenced receptiveness to AD predictive–diagnostic procedures. Highlights Indigenous populations in high‐income countries face a higher risk of dementia, making Alzheimer's disease (AD) biomarker and diagnostic research a critical priority in these groups. Despite this, Indigenous and Latin American populations remain among the most underrepresented in dementia research. In a sample of Indigenous (Mapuche) and non‐Indigenous older adults in Chile, most participants reported willingness to use AD biomarkers and diagnostic procedures. In fully adjusted models, Mapuche individuals were significantly less willing to undergo neuropsychological testing, blood tests, and brain imaging for AD risk prediction. Willingness to use AD biomarkers varied by ethnic identity and was influenced by age, social determinants, and attitudes toward AD.

Most life forms on earth, including the cold-adapted bacteria from the polar regions, are being affected by global warming. To better understand how global warming may affect Antarctic bacteria, the heat-stress response of cold-adapted Cryobacterium sp. SO1 at the transcript level was determined in this study. A Cryobacterium sp. SO1 culture was grown at 20 °C which was its optimal growth temperature and subsequently exposed to a higher temperature of 25 °C that inhibited growth for 3 h. The transcriptome of strain SO1 was isolated, and RNA-sequencing (RNA-seq) was performed and analyzed using bioinformatics tools. The global transcriptome revealed 169 differentially expressed genes (DEGs), 108 of which were up-regulated and 61 of which were down-regulated. The strain SO1 DEGs were classified into seven categories: signal transduction, DNA modification and repair mechanisms, oxidative-stress defence, metabolism-related, cellular translational machinery, cell growth-related, and programmed cell death-related genes. Strain SO1 altered those genes to cope with the heat stress. Transposase gene up-regulation, in particular, probably promoted genome transposition in an attempt to generate genetically diverse cells in the population in the hope that some will be able to withstand the growth inhibitory temperature. Overall, the findings of this study shed some light on how Cryobacterium sp. SO1, and other Antarctic bacteria in general, will probably respond to global warming.

Thirteen out of the 15 known Cryobacterium spp. were from extremely cold environments. However, the fundamental question on their cold adaptation strategies to survive in the cold has not been addressed adequately. Hence, this work was conducted to determine the Cryobacterium sp. SO1 cold adaptation strategies. Cryobacterium sp. SO1 that grew optimally at 20 °C was exposed to a sub-optimal temperature of 10 °C. Its mRNA was extracted, sequenced, and analyzed. Strain SO1 global transcriptional profiles revealed a total of 182 differential expressed genes. Four hydrolases, a clp protease, and novel YraN family endonuclease that were related to the programmed cell death pathway were upregulated, indicating that the temperature drop was probably lethal to some cells. Three highly upregulated transcriptional regulators were likely to be the key components to regulate genome-wide expression to adapt to the cold. Meanwhile, the oligo-ribonuclease and a Clp protease gene were upregulated probably to remove accumulated misfolded mRNA and proteins, respectively. The SerB gene was upregulated probably to provide more L-serine residue for the biosynthesis of cold-adapted proteins. Interestingly, most of the stress protein genes in the genome, such as the reactive oxygen species (ROS)-scavenging enzymes were not upregulated. Instead, strain SO1 upregulated the six ribosomal genes which were the target of oxidative nucleobase damage caused by the ROS. This mechanism was probably to ensure that the protein biosynthesis machinery was not affected. Overall, strain SO1 had all the necessary genes and well-coordinated mechanisms to adapt to the sub-optimal growth temperature.