The evolution of eukaryotic life was predicated on the development of organelles such as mitochondria and plastids. During this complex process of organellogenesis, the host cell and the engulfed prokaryote became genetically codependent, with the integration of genes from the endosymbiont into the host nuclear genome and subsequent gene loss from the endosymbiont. This process required that horizontally transferred genes become active and properly regulated despite inherent differences in genetic features between donor (endosymbiont) and recipient (host). Although this genetic reorganization is considered critical for early stages of organellogenesis, we have little knowledge about the mechanisms governing this process. The photosynthetic amoeba Paulinella micropora offers a unique opportunity to study early evolutionary events associated with organellogenesis and primary endosymbiosis. This amoeba harbors a "chromatophore," a nascent photosynthetic organelle derived from a relatively recent cyanobacterial association (similar to 120 million years ago) that is independent of the evolution of primary plastids in plants (initiated similar to 1.5 billion years ago). Analysis of the genome and transcriptome of Paulinella revealed that retrotransposition of endosymbiont-derived nuclear genes was critical for their domestication in the host. These retrocopied genes involved in photoprotection in cyanobacteria became expanded gene families and were "rewired," acquiring light-responsive regulatory elements that function in the host. The establishment of host control of endosymbiont-derived genes likely enabled the cell to withstand photo-oxidative stress generated by oxygenic photosynthesis in the nascent organelle. These results provide insights into the genetic mechanisms and evolutionary pressures that facilitated the metabolic integration of the host-endosymbiont association and sustained the evolution of a photosynthetic organelle.

The chemical industry is responsible for about 5% of global CO2 emissions and is key to achieving net-zero targets. Decarbonizing this industry, nevertheless, faces particular challenges given the widespread use of carbon-rich raw materials, the need for high-temperature heat, and the complex global value chains. Multiple technology routes are now available for producing chemicals with net-zero CO2 emissions based on biomass, recycling, and carbon capture, utilization, and storage. However, the extent to which these routes are viable with respect to local availability of energy and natural resources remains unclear. In this review, we compare net-zero routes by quantifying their energy, land, and water requirements and the corresponding induced resource scarcity at the country level and further discuss the technical and environmental viability of a net-zero chemical industry. We find that a net-zero chemical industry will require location-specific inte-grated solutions that combine net-zero routes with circular approaches and demand-side measures and might result in a reshaping of the global chemicals trade.

Human-induced abiotic global environmental changes (GECs) and the spread of non-native invasive species are rapidly altering ecosystems. Understanding the relative and interactive effects of invasion and GECs is critical for informing ecosystem adaptation and management, but this information has not been synthesized. We conducted a meta-analysis to investigate effects of invasions, GECs, and their combined influences on native ecosystems. We found 458 cases from 95 published studies that reported individual and combined effects of invasions and a GEC stressor, which was most commonly warming, drought, or nitrogen addition. We calculated standardized effect sizes (Hedges' d) for individual and combined treatments and classified interactions as additive (sum of individual treatment effects), antagonistic (smaller than expected), or synergistic (outside the expected range). The ecological effects of GECs varied, with detrimental effects more likely with drought than the other GECs. Invasions were more strongly detrimental, on average, than GECs. Invasion and GEC interactions were mostly antagonistic, but synergistic interactions occurred in >25% of cases and mostly led to more detrimental outcomes for ecosystems. While interactive effects were most often smaller than expected from individual invasion and GEC effects, synergisms were not rare and occurred across ecological responses from the individual to the ecosystem scale. Overall, interactions between invasions and GECs were typically no worse than the effects of invasions alone, highlighting the importance of managing invasions locally as a crucial step toward reducing harm from multiple global changes.

Context. Carbon-enhanced metal-poor (CEMP) stars ([C/Fe] > 0.7) are known to exist in large numbers at low metallicity in the Milky Way halo and are important tracers of early Galactic chemical evolution. However, very few stars of this kind have been identified in the classical dwarf spheroidal (dSph) galaxies, and detailed abundances, including neutron-capture element abundances, have only been reported for 13 stars.Aims. We aim to derive detailed abundances of six CEMP stars identified in the Carina dSph and compare the abundances to CEMP stars in other dSph galaxies and the Milky Way halo. This is the largest sample of CEMP stars in a dSph galaxy analysed to date.Methods. One-dimensional local thermodynamic equilibrium (LTE) elemental abundances are derived via equivalent width and spectral synthesis using high-resolution spectra of the six stars obtained with the MIKE spectrograph at Las Campanas Observatory.Results. We derived abundances or upper limits for up to 27 elements from C to Os in the six stars. Our analysis reveals one of the stars to be a CEMP-no star with very low neutron-capture element abundances. In contrast, the other five stars all show enhancements in neutron-capture elements in addition to their carbon enhancement, classifying them as CEMP-s and -r/s stars. The six stars have similar a and iron-peak element abundances to other stars in Carina, except for the CEMP-no star, which shows enhancement in Na, Mg, and Si. We explored the absolute carbon abundances (A(C)) of CEMP stars in dSph galaxies and find similar behaviour to that seen for Milky Way halo CEMP stars, but highlight that CEMP-r/s stars primarily have very high A(C) values. We also compared the neutron-capture element abundances of the CEMP-r/s stars in our sample to recent i-process yields, which provide a good match to the derived abundances.

Tidal disruptions of stars by stellar-mass black holes are expected to occur frequently in dense star clusters. Building upon previous studies that performed hydrodynamic simulations of these encounters, we explore the formation and long-term evolution of the thick, super-Eddington accretion disks formed. We build a disk model that includes fallback of material from the tidal disruption, accretion onto the black hole, and disk mass losses through winds launched in association with the super-Eddington flow. We demonstrate that bright transients are expected when radiation from the central engine powered by accretion onto the black hole is reprocessed at large radii by the optically-thick disk wind. By combining hydrodynamic simulations of these disruption events with our disk + wind model, we compute light curves of these wind-reprocessed transients for a wide range of stellar masses and encounter penetration depths. We find typical peak bolometric luminosities of roughly 10( 41) -10 (44 )erg s (-1 )(depending mostly on accretion physics parameters) and temperatures of roughly 10( 5) -10( 6) K, suggesting peak emission in the ultraviolet/blue bands. We predict all-sky surveys such as the Vera Rubin Observatory and ULTRASAT will detect up to thousands of these events per year in dense star clusters out to distances of several Gpc.

The resonantly scattered Ly & alpha; line illuminates the extended halos of neutral hydrogen in the circumgalactic medium of galaxies. We present integral field Keck Cosmic Web Imager observations of double-peaked, spatially extended Ly & alpha; emission in 12 relatively low-mass (M (⋆) & SIM; 10(9) M-& ODOT;) z & SIM; 2 galaxies characterized by extreme nebular emission lines. Using individual spaxels and small bins as well as radially binned profiles of larger regions, we find that for most objects in the sample the Ly & alpha; blue-to-red peak ratio increases, the peak separation decreases, and the fraction of flux emerging at line center increases with radius. We use new radiative transfer simulations to model each galaxy with a clumpy, multiphase outflow with radially varying outflow velocity, and self-consistently apply the same velocity model to the low-ionization interstellar absorption lines. These models reproduce the trends of peak ratio, peak separation, and trough depth with radius, and broadly reconcile outflow velocities inferred from Ly & alpha; and absorption lines. The galaxies in our sample are well-described by a model in which neutral, outflowing clumps are embedded in a hotter, more highly ionized inter-clump medium (ICM), whose residual neutral content produces absorption at the systemic redshift. The peak ratio, peak separation, and trough flux fraction are primarily governed by the line-of-sight component of the outflow velocity, the H i column density, and the residual neutral density in the ICM respectively. The azimuthal asymmetries in the line profile further suggest nonradial gas motions at large radii and variations in the H i column density in the outer halos.

We forecast the prospects for cross-correlating future line intensity mapping (LIM) surveys with the current and future Ly-alpha forest measurements. Using large cosmological hydrodynamic simulations, we model the emission from the CO rotational transition in the CO Mapping Array Project LIM experiment at the 5-yr benchmark and the Ly-alpha forest absorption signal for extended Baryon Acoustic Oscillations (BOSS), Dark energy survey instrument (DESI), and Prime Focus multiplex Spectroscopy survey (PFS). We show that CO xLy-alpha forest significantly enhances the detection signal-to-noise ratio (S/N) of CO, with up to 300 per cent improvement when correlated with the PFS Ly-alpha forest survey and a 50-75 per cent enhancement with the available eBOSS or the upcoming DESI observations. This is competitive with even CO xspectroscopic galaxy surveys. Furthermore, our study suggests that the clustering of CO emission is tightly constrained by CO x Ly-alpha forest due to the increased sensitivity and the simplicity of Ly-alpha absorption modelling. Foreground contamination or systematics are expected not to be shared between LIM and Ly-alpha forest observations, providing an unbiased inference. Ly-alpha forest will aid in detecting the first LIM signals. We also estimate that [C II] x Ly-alpha forest measurements from Experiment for Cryogenic Large-Aperture Intensity Mapping and DESI/eBOSS should have a larger S/N than planned [C II] x quasar observations by about an order of magnitude.

Global climate models predict that the frequency and intensity of precipitation events will increase in many regions across the world. However, the biosphere-climate feedback to elevated precipitation (eP) remains elusive. Here, we report a study on one of the longest field experiments assessing the effects of eP, alone or in combination with other climate change drivers such as elevated CO2 (eCO(2)), warming and nitrogen deposition. Soil total carbon (C) decreased after a decade of eP treatment, while plant root production decreased after 2 years. To explain this asynchrony, we found that the relative abundances of fungal genes associated with chitin and protein degradation increased and were positively correlated with bacteriophage genes, suggesting a potential viral shunt in C degradation. In addition, eP increased the relative abundances of microbial stress tolerance genes, which are essential for coping with environmental stressors. Microbial responses to eP were phylogenetically conserved. The effects of eP on soil total C, root production, and microbes were interactively affected by eCO(2). Collectively, we demonstrate that long-term eP induces soil C loss, owing to changes in microbial community composition, functional traits, root production, and soil moisture. Our study unveils an important, previously unknown biosphere-climate feedback in Mediterranean-type water-limited ecosystems, namely how eP induces soil C loss via microbe-plant-soil interplay.

Oxygen deficient zones (ODZs) account for about 30% of total oceanic fixed nitrogen loss via processes including denitrification, a microbially mediated pathway proceeding stepwise from NO3- to N2. This process may be performed entirely by complete denitrifiers capable of all four enzymatic steps, but many organisms possess only partial denitrification pathways, either producing or consuming key intermediates such as the greenhouse gas N2O. Metagenomics and marker gene surveys have revealed a diversity of denitrification genes within ODZs, but whether these genes co-occur within complete or partial denitrifiers and the identities of denitrifying taxa remain open questions. We assemble genomes from metagenomes spanning the ETNP and Arabian Sea, and map these metagenome-assembled genomes (MAGs) to 56 metagenomes from all three major ODZs to reveal the predominance of partial denitrifiers, particularly single-step denitrifiers. We find niche differentiation among nitrogen-cycling organisms, with communities performing each nitrogen transformation distinct in taxonomic identity and motility traits. Our collection of 962 MAGs presents the largest collection of pelagic ODZ microorganisms and reveals a clearer picture of the nitrogen cycling community within this environment.