搜索结果：Chemistry & biodiversity

Introduced invasive plants can alter the composition of resident soil microbial communities, which may disrupt ecosystem function and facilitate continued invasion success. Wavyleaf basketgrass (Oplismenus undulatifolius) is a high-risk, non-native invasive plant currently confined to the Mid-Atlantic United States but with the potential to colonize forest understory across the eastern United States. In this study, we characterized soil microbial communities from locations spanning the invaded range using amplicon sequencing to understand the impacts of wavyleaf basketgrass establishment on resident soil microbiomes. We compared the diversity and structure of microbial communities from invaded and uninvaded forest soils, as well from wavyleaf basketgrass rhizospheres. Invasion by wavyleaf basketgrass was associated with an increase in fungal diversity within sampling locations but a decrease in diversity across sampling locations. Changes in the relative abundance of specific sequence variants indicated a small number of resident microbes may be amplified in wavyleaf basketgrass rhizospheres. Finally, fungal alpha diversity was correlated with soil chemistry variables in uninvaded plots but not in invaded plots, and increased plant ground cover attributed to wavyleaf basketgrass invasion was positively correlated with fungal diversity. Together, these patterns suggest that wavyleaf basketgrass recruits diverse microbial associates from the environment, homogenizes soil microbiomes across invaded locations, and overrides existing environmental selection pressures exerted by soil chemistry profiles. Ongoing expansion of the species' invaded range may produce similar impacts in new environments. Understanding whether and how microbial communities are altered by plant invasion provides important information about the impact of introduced species on natural resources, nutrient cycling, and biodiversity that influence subsequent land management and ecosystem restoration decisions. We document biotic homogenization of resident soil microbes across geographically disparate locations following a relatively recent plant invasion. We further provide evidence suggesting microbial community changes are linked to the enrichment of specific taxa from the invasive plant's rhizosphere and possible buffering of these communities against other environmental selective pressures.

Bioactive compounds are natural or synthetic substances with regulatory roles in metabolic processes. Brazil, known for its rich biodiversity and strong expertise in organic chemistry, holds great potential for discovering bioactive molecules. However, the vast amount of data generated in this field is often scattered and difficult to access. The IRACEMA (Innovative Research, Analysis, and Computational Exploration of Molecules Assembled in Brazil) project addresses this challenge by establishing the first comprehensive database of synthetic bioactive compounds in Brazil. This platform integrates biological activity data, manually curated from the literature, with cheminformatics-based predictions of physicochemical and ADME properties to facilitate the exploration of structure-activity relationships (SARs) by end users. The project's technical architecture employs modern web technologies for both frontend (React) and backend (NestJS/Node.js and Python/Flask microservices) development. The system delivers an interactive platform for molecular visualization and analysis, with PostgreSQL and Prisma ensuring robust data management. By democratizing access to data, IRACEMA (available at https://iracema.fcf.usp.br/) strengthens Brazil's position in bioactive compound research, bridging the gap between academic discoveries and real-world applications.

Biodiversity plays a fundamental role in ecosystem structure, function, and stability, but its response to environmental gradients is poorly understood in Central Asia. We studied plant species richness, phylogenetic diversity, and community phylogenetic structure along elevational, temperature, and precipitation gradients in Surkhandarya province of southern Uzbekistan. Data were compiled from a 5-year field survey (2020-2024), herbarium records (TASH, ASH, BM, E, H, LE, M, MW, TAD, MOSM), and digital records from the Plantarium database (plantarium.ru), totalling over 64,500 occurrence records. The flora comprises 2202 species across 615 genera and 96 families, including 62 endemics. Species richness and PD exhibited a left-skewed, hump-shaped pattern with a peak at 1000-1100 m, while high-elevation communities were phylogenetically clustered due to environmental filtering. Mid-elevations showed phylogenetic overdispersion, reflecting the coexistence of distantly related species. Along climatic gradients, species richness peaked at intermediate temperatures (8°C-12°C) and precipitation (400-500 mm), with phylogenetic structure similarly reflecting clustering at extremes and overdispersion at intermediate conditions. Low-elevation communities were dominated by drought- and salt-tolerant families (Poaceae, Asteraceae, Amaranthaceae), whereas mid-elevations supported the highest family diversity. Using endemic and Red Book species records (1504 occurrences of 140 species), a proximity-weighted conservation prioritization identified a minimal set of areas covering 7.43% of the region, with 4.56% requiring expansion beyond existing protected areas to achieve complete species representation.

Lead (Pb) pollution in water bodies poses significant threats to aquatic biodiversity, highlighting the need for assessment through suitable bioindicators for monitoring and evaluating ecosystem health. This field study was carried out to evaluate the bioaccumulation potential of freshwater snail species in Sargodha, Pakistan. The snail species were collected between September and November, 2023, from two different types of freshwater bodies (lentic and lotic) and identified as Indoplanorbis exustus and Lymnaea acuminata. The Pb concentration was assessed in snail soft bodies and water samples through atomic absorption spectrometry. The results showcased the mean Pb concentration of 0.1572 ppm (dw) in I. exustus, 0.1487 ppm (dw) in L. acuminata, and 0.0344 ppm (ww) in both types of water samples. There were significant differences among the water bodies, with stagnant water bodies having more Pb contamination than flowing ones. Additionally, significant differences were ascertained between the mean Pb concentration of both snail species and water samples. However, linear regression analysis showed an inverse relationship between the concentrations of Pb in water and both snail species. In addition, the bioconcentration factor (BCF) values calculated for snail species showed that both I. exustus and L. acuminata were equally good bioaccumulators of Pb in lentic and lotic water bodies. In conclusion, the study findings emphasized the urgent need for freshwater monitoring and pollution management in the region.

The structure and function of many proteins are regulated post-translationally through glycan attachment. These glycans, assembled via competing enzymatic reactions, generate diverse glycoform populations - variants sharing a protein backbone but differing in glycan structures. While current analyses often focus on individual glycoforms, we demonstrate that population-level glycoform analysis - integrating spectral, biosynthetic, and physicochemical relationships - reveals new insights into glycoprotein regulation. Applied to immunoglobulin subclasses and antithrombin III (AT3), this approach provides comprehensive coverage of glycoform repertoires from human and murine plasma and biopharmaceuticals. It also enables sensitive quantification of glycosylation changes arising from in vitro manipulations or in vivo infections. Finally, we introduce a statistical framework adapted from ecological biodiversity studies, revealing that both IgG and AT3 exhibit skewed glycoform distributions shaped by biosynthetic constraints and degradation. Our findings demonstrate the added value of population-level glycoform analysis in understanding protein function and regulation through glycosylation.

Amaranthus spinosus L. is a member of the Amaranthaceae family, commonly known as the spiny amaranth, or spiny pigweed. It is native to the tropical Americas, but is present on most continents as an introduced species, noxious weed, and can be a serious weed of rice cultivation in Asia. In Egypt, the Nile Delta, particularly Cairo, is the home of spiny amaranth; however, it has recently been recorded in the Nile Valley (Aswan area) colonizing different habitats such as roadsides, depressions, Khor and river banks. This study aimed to study the current distribution of spiny amaranth in the Aswan area and its associated species. It also aims at studying their life and growth forms, habitats, soil characteristics, local and global distributions, local threats, and spiny amaranth seed characteristics. Five sites along the river Nile in Aswan city was surveyed from the period of 2018 until 2025 in four identified habitats (Roadsides, depressions, khor, and river banks). Forty species were recorded associated with spiny amaranth, belonging to 38 genera and 16 families. Therophytes (15 species) followed by phanerophytes (14 species) were the most represented life form. All recorded species inhabit the Nile region, and most of the 12 taxa were pantropical. Most studied species (32.5% of the total threatened species) suffer from at least one type of threat. They mostly suffer from habitat loss due to industrial, urban, and tourist development. Soil samples were analyzed for edaphic variables. The relative importance of a certain environmental factor on the distribution of the recorded species across the four habitats were performed using PCORD (v6.22 software). The spiny amaranth seed colors are mainly dark brown to reddish brown, lenticular shape, glabrous and matte surface, acute apex, and obtuse to rounded base, hilum marginal, sub-basal, and slightly eccentric. Its length ranged from 7.24 to 7.84 mm, and its width varied between 7.27 and 7.77 mm. The authors recommended that monitoring the behavior of alien species and conducting ongoing surveys are crucial for biodiversity conservation.

The widespread use of allopathic medications has significantly improved modern healthcare; however, their associated side effects and the rapid emergence of antimicrobial resistance have intensified the search for safer and more effective therapeutic alternatives. In this context, natural resources, especially Himalayan medicinal herbs, have resurfaced as potential alternatives due to their therapeutic potency and biocompatibility. The Himalayan region offers a unique reservoir of bioactive plants suitable for biomedical applications based on nanotechnology. It is well known for its high biodiversity and traditional medicinal uses. This review assesses the biological applications of bionanoparticles derived from Himalayan herbs, including antibacterial, antifungal, antiviral, antiparasitic, antioxidant, antidiabetic, and anticancer properties. It also critically looks at recent developments in the green synthesis of these bionanoparticles. Furthermore, the mechanisms of action that explain their improved therapeutic efficacy are addressed. Overall, this review emphasizes the scientific value of Himalayan herb-based nanobiomedicines as viable, sustainable substitutes for traditional allopathic medications, as well as their potential for future biomedical applications.

Coastal marshes, recognized as effective organic carbon (OC) sinks, have gained attention for their potential contribution to climate mitigation through protection and restoration. However, the climate mitigation potential of Nordic coastal marshes remains understudied, likely due to their heterogeneous and often non-tidal nature. To fill this gap, we examined soil OC storage and accumulation rates, and the effects of grazing, a common management practice, across eight Nordic coastal marsh areas spanning broad climate and environmental gradients. We also assessed soil methane emissions in selected areas. The Nordic marshes studied store a median of 7 kg OC m-2 (interquartile range, IQR: 6-8) in the top 15-35 cm of soil and accumulate 41 g OC m-2 yr.-1 (IQR: 32-47). Considering only the additional OC, attributed to the presence of the marsh habitat, these values drop to 4 kg OC m-2 (IQR: 2-6) and 21 g OC m-2 yr.-1 (IQR: 11-33). Globally, both rates are comparatively low. OC stocks and accumulation rates increased with marsh age, root: shoot ratio (stress adaptation), and δ15N (fast N cycling), but declined with soil δ13C (related to faster decomposition under warmer conditions and sandier soils). Danish marshes had the highest but also most vulnerable OC stocks due to faster turnover, labile compounds, and coarser soil grain sizes. Although grazing only weakly increased soil OC stocks and had no effect on OC accumulation rates, it significantly reduced methane fluxes compared to ungrazed marshes. In ungrazed areas, methane emissions weakened the carbon sink by 32% in Finland and 68% in Denmark. However, estimated greenhouse gas emissions from on-site cattle, even at low grazing intensity, largely outweighed the coastal marsh climate benefits. A comprehensive Nordic marsh management strategy is needed, extending beyond the focus on their limited, yet relevant, role in climate mitigation, and considering biodiversity, coastal protection and nutrient retention.

The ferruginous duricrust (canga) in the Iron Quadrangle (IQ), Minas Gerais, Brazil, occurs within the Campo Rupestre and presents remarkable levels of endemism and species richness. Despite the recognized importance of microorganisms for the maintenance of this ecosystem, current molecular-based studies reveal that both the taxonomic composition and the ecological functions of the canga microbiome are undiscovered. In this study, eighteen samples of canga were collected from the Serra da Piedade State Natural Monument, and their taxonomic diversity was investigated using 16S rRNA metabarcoding. Additionally, the influence of physicochemical variables on microbial diversity and community structure was estimated using statistical tools. Most of the 856,667 reads clustered into ASVs corresponded to Bacteria (99.7%), and the most abundant of the 184 identified genera were Conexibacter, Acidothermus and Bryobacter. Microbial diversity was explained by a combination of physicochemical variables, such as organic matter (OM), iron (Fe), aluminum (Al) and pH, whereas microbial community structure was influenced by the concentrations of Fe, Al and the cation exchange capacity (CEC). Functional prediction analysis based on the main genera identified in the samples indicated that the denitrification pathway may play an important role in the ecosystem. The investigation of the genera and their metabolic pathways based on the literature revealed that they are unexplored and emphasized the biodiversity hotspot yet to be explored in ferruginous duricrust. Therefore, our results reinforce the importance of further studies in this environment, both for future biotechnological applications and for appropriate management and preservation actions.

Microbial-derived secondary metabolites (SMs) hold great therapeutic potential but are predominantly discovered from cultured species, representing only a fraction of microbial biodiversity. Advances in metagenomics have unveiled reservoirs of biosynthetic gene clusters (BGCs), but translating genomic sequences into precise chemical structures remains challenging owing to the structural complexity of cryptic BGCs and the context-dependent substrate tolerance and cross-reactivity of modular biosynthetic domains. Here we present DeepSeMS, a transformer-based large language model that accurately predicts secondary metabolite chemical structures from BGC sequences. By encoding biosynthetic genes as functional domains and leveraging a feature-aligned data augmentation, DeepSeMS outperformed existing methods and successfully generated chemically valid predictions for 96.38% of cryptic BGCs. Applying DeepSeMS to a global ocean metagenome, we characterized over 60,000 secondary metabolites, revealing chemical diversity, ecological specificity and considerable biomedical potential, especially as antibiotics. This study underscores the capability of deep learning-driven approaches in revealing hidden biosynthetic potential of Earth's largest, yet largely unexplored, microbial ecosystem.

Soil salinity, characterized by the accumulation of soluble salts, poses a significant global threat to agriculture, affecting over one billion hectares. It induces osmotic stress and ion toxicity, significantly diminishing crop yields and arable land. Egypt, heavily reliant on the Nile Delta, experiences severe salinization resulting from irrigation practices, climate change, and inherent aridity. This escalating crisis compromises agricultural productivity and food security, necessitating urgent global solutions. A total of 103 plant taxa were documented. Asteraceae (22 species) and Poaceae (13 species) constituted the most diverse families. Annuals (50.0%) and therophytes (49.5%) represented the predominant life forms, while biregional species (36.9%) formed the largest chorological group. Soil physicochemical properties, including particle size distribution, pH, EC, TDS, organic matter, saturation percentage, SAR, available N, P, and K, major ions (Ca² ⁺ , Mg² ⁺ , Na ⁺ , K ⁺ , Cl ⁻ , HCO₃ ⁻ , SO₄²⁻), and CaCO₃%, were determined in all stands. Two-Way Indicator Species Analysis (TWINSPAN) and Detrended Correspondence Analysis (DCA) classified the studied stands into six distinct groups. Stands within each group exhibited ecological similarity. Each vegetation group possessed its own set of indicator plant species, and the soil factors most closely associated with them.

Nanocarrier-mediated delivery of double-stranded RNA (dsRNA) is a promising strategy for plant disease control. Our previous study has shown that the self-assembled ε-poly-l-lysine/carboxymethyl chitosan (ε-PL@CMCS) nanocarrier significantly improves the efficiency of RNA interference (RNAi) against Rhizoctonia solani AG3 TB. However, the molecular mechanisms underlying this enhancement and the potential ecological impacts on phyllosphere microbial communities remain unclear. In this study, we confirmed that dsRsGH1@ε-PL@CMCS had no adverse effects on the growth and development of plants. Transcriptome analysis revealed that DEGs were significantly enriched in 'SNARE interactions in vesicular transport' pathway. Among them, dsRsGH1@ε-PL@CMCS specifically upregulate the vesicle transport protein SEC22 in Nicotiana tabacum. Surface plasmon resonance (SPR) assay demonstrated that the dsRsGH1@ε-PL@CMCS binds to SEC22 protein with 7.6-fold higher affinity than that of the naked dsRsGH1. Silencing SEC22 in the dsRsGH1@ε-PL@CMCS treatment reduced the silencing efficiency of RsGH1 from 53.3% to 39%, confirming its essential role. Concurrently, high-throughput sequencing revealed that SIGS treatments did not disrupt bacterial community structure but increased fungal diversity and suppressed the pathogen, while enriching beneficial fungi such as Tulasnella. Our findings elucidate a molecular link between nano-bioprotectant dsRsGH1@ε-PL@CMCS-enhanced RNAi and host vesicle transport, while confirming the biocompatible and microbiome-modulating potential. This provides a dual perspective for developing efficient and sustainable RNAi-based strategies for protecting plants.

Parabiotics (also termed paraprobiotics) are defined as non-viable microbial cells or their components, including peptidoglycans, teichoic acids, surface proteins, that confer health benefits without requiring viability which distinguishes them from traditional probiotics. Their non-viable nature eliminates risks such as microbial translocation, bacteremia, and sepsis, making them suitable for vulnerable populations including immunocompromised, critically ill, paediatric and elderly individuals. In addition, parabiotic exhibit improved thermal stability, extended shelf life, and easier incorporation into functional foods, nutraceuticals, and pharmaceutical formulations without cold-chain requirements. Mechanistically, parabiotics retain immunomodulatory, anti-inflammatory and have barrier-enhancing activities through interactions with host pattern recognition receptors, including Toll-like receptors, modulation of cytokine responses, and reinforcement of gut epithelial integrity. Preclinical and clinical studies support their therapeutic potential such as in case of heat-killed Lactobacillus acidophilus LB (L. acidophilus) has shown efficiency in managing acute paediatric diarrhoea, while heat-inactivated Lacticaseibacillus paracasei PS23 (Lcb. paracasei) has demonstrated improvements in muscle strength and inflammatory markers, including reduced C-reactive protein and interleukin-6 and increased interlukin-10 in elderly individuals. Similarly, inactivated Lactiplantibacillus plantarum (Lpb. plantarum) and Bifidobacterium strains have been associated with benefits in irritable bowel syndrome, atopic dermatitis, respiratory infections, visceral fat reduction, and antibiotic-associated dysbiosis. Synergistic combinations with prebiotics, postbiotics and related bioactives further enhance therapeutic outcomes in inflammatory, metabolic and infectious conditions. Advances in metagenomics, next-generation sequencing, proteomics, metabolomics, CRISPR-Cas systems, and synthetic biology are accelerating strain characterization, functional evaluation, and scalable production. Despite ongoing challenges in standardization and regulated harmonization, parabiotics represent a safe and effective approach for microbiome-targeted interventions. This review synthesizes current evidence on their therapeutic applications, technological advancements, and translational potential, highlighting their role in precision health and next-generation functional nutrition.

Cooperation is the cornerstone of human societies, and its emergence is firmly linked to enhanced tolerance and egalitarianism. However, evidence of profuse cooperation in less tolerant and despotic societies challenges this predominant view. The overarching interdependency hypothesis may resolve the conundrum. It posits that group-level interdependencies, like strength in numbers in colonially nesting species or allomaternal care in cooperatively breeding species, promote indiscriminate cooperation through enhanced tolerance. Crucially, this hypothesis also predicts that dyadic interdependence like friendships, nepotistic biases, or coalitions, selectively enhance tolerance, fostering discriminate cooperation in despotic species. Species belonging to Macaca, which have a similar social organization, yet remarkable variation in tolerance, hierarchy steepness, nepotistic biases, and coalitionary tendencies, provide an opportunity for testing the interdependency hypothesis. In social group settings, we experimentally study cooperation, prosociality, and tolerance in six macaque species spanning a tolerance gradient. Our findings reveal high dyadic cooperation in despotic societies, yet this cooperation is restricted to a few partners. Dyadic prosociality, kinship, and tolerance positively predict cooperation. Further, our agent-based models demonstrate that despotic societies have fewer but more stable bonds and, thus, higher dyadic interdependencies than in egalitarian societies. Our results suggest that interdependencies facilitate the emergence and maintenance of cooperation.

This study examined whether a plant-derived protein diet combined with multi-strain probiotics protects against sarcopenia in naturally aged rats (21 months old) via the gut-muscle axis following a 12-week intervention.Compared with the aged control group,The combined intervention increased grip strength by 55.96%, gastrocnemius index by 23.49%, and quadriceps index by 28.29%, while reducing oxidative stress and inflammation (MDA by 39.80%, TNF-α by 42.19%, IL-6 by 65.81%). Mechanistically, it enhanced gut microbiota diversity, enriched beneficial taxa (e.g., Alistipes, Lachnospiraceae_UCG-006), elevated fecal SCFAs, modulated serum amino acids, and upregulated muscle synthesis-related proteins (AMPK-α1, p70 S6K). These findings suggest that a plant-derived protein diet supplemented with multi-strain probiotics represents a promising nutritional strategy to counteract age-related sarcopenia and support healthy ageing.

Accurate classification of postmortem decomposition stages is a critical step in estimating the postmortem interval (PMI) and tracing the initial decomposition environment. Research on the decomposition staging methodological system is gradually shifting from empirical observation to the establishment of systems based on multidimensional quantitative indicators. This paper focuses on two key pathways, "macroscopic morphological evolution" and "microscopic molecular succession", and systema-tically reviews the evolutionary patterns and applicability of the decomposition staging system in three typical environmental media: surface exposure, burial, and aquatic systems. It also summarizes research progress in constructing stage classification models utilizing microbiome and metabolomic features. Furthermore, it highlights the integrated application of decomposition characteristic quantification techniques, multi-omics data integration, and machine learning algorithms in decomposition analysis systems. It analyzes the prospects and challenges of applying these approaches to build a standardized and practical decomposition staging system, aiming to provide theoretical support for establishing a decomposition staging system with high accuracy and strong adaptability to different environments. 准确划分尸体腐败阶段有利于死亡时间推断与初始腐败环境的溯源。尸体腐败阶段分期方法体系的研究正逐步从经验判断转向基于多维量化指标的建立。本文聚焦于“宏观形态演变”与“微观分子演替”两条路径，系统综述地表暴露、埋葬与水体三类典型环境介质中尸体腐败分期体系的演化规律与适用特征，梳理总结利用微生物组学与代谢组学特征构建分期判别模型的研究进展，重点探讨腐败特征量化技术、多组学数据整合以及机器学习算法在腐败分析体系中的融合应用，并分析其在构建标准化、可实战化腐败分期体系中的应用前景与挑战，以期为建立精度高、环境适应性强的尸体腐败分期体系提供理论支撑。.

To better understand the dynamics of per- and polyfluoroalkyl substances (PFAS) in complex freshwater ecosystems, we performed a systematic meta-analysis of PFAS distributions and spatiotemporal variance in biota of the Laurentian Great Lakes watersheds. We reviewed 50 publications that contained 2489 records (primarily of fish and birds) spanning 42 years of biological sampling. Using this dataset, we built generalized additive models for six compounds-perfluorooctanesulfonic acid (PFOS) and five perfluoroalkyl carboxylic acids (PFCAs)-routinely detected in biological tissues. Estimated concentrations of PFOS, the dominant compound in biota, increased along a lake gradient from west (Lake Superior) to east (Lake Ontario), and PFCA levels also varied across the lakes. Modeled temporal trends of PFOS in biota were highly significant but non-linear, and may be correlated with industrial production, the timeline of compound phase-out, food web shifts, and lake-specific conditions. In the eastern lakes, biotic PFOS concentrations were highly variable through time, spanning one to two orders of magnitude, and model estimates generally declined following industrial phase-out of the compound. In the western lakes, PFOS levels did not demonstrate substantial changes from lower baseline concentrations. PFOS, but not PFCA, levels biomagnified from primary producers to apex predators across the Great Lakes. Model output indicated that eggs, blood, and liver samples were consistently the most contaminated tissues. Our review also revealed several data constraints in the literature revolving around lake coverage, taxonomic biases, and methodological inconsistencies. Addressing these data gaps will maximize the inferential ability of future synthetic studies of PFAS. Per‐ and polyfluoroalkyl substances (PFAS), known as “forever chemicals,” can remain in the environment for decades and pose significant concerns for the Laurentian Great Lakes. By analyzing PFAS data for Great Lakes biota over 42 years, we found that PFAS burdens across multiple taxonomic groups showed a distinct west‐to‐east increase from Lake Superior to Lake Ontario. Concentrations within organisms were driven by their position in the food chain, their lifestyle, and the affinity of PFAS for protein and fatty tissues. Voluntary phase‐out of one compound has led to declines in body burdens, showing promising potential for reducing contamination overall in the Great Lakes. This review also identifies research gaps in what taxa have been sampled, where samples have been collected, and how concentration data have been reported, and we provide recommendations for future research.

Antarctica hosts a highly endemic and diverse benthic marine fauna. Despite this biodiversity, the Antarctic marine food web remains structurally simple, rendering the ecosystem particularly vulnerable to environmental stressors. Benthic organisms, due to their sedentary nature, long lifespans, and close interaction with the sediment-water interface, are widely regarded as effective sentinels of ecological change. In this study, we extended a previously validated QuEChERS-based extraction protocol, originally developed for Adamussium colbecki organisms, to assess its applicability across additional Antarctic benthic taxa, including Sphaerotylus antarcticus, Odontaster validus, Trematomus bernacchii, and Laternula elliptica. The extraction method was used in combination with LC-MS/MS analysis for the determination of emerging contaminants in both targeted and suspect screening modes. Method performance was evaluated for 23 targeted emerging contaminants (ECs), yielding recovery rates of 58-116% and matrix effects between 62 and 108% for most compounds, confirming the method's suitability for taxonomically diverse matrices. Samples collected during Antarctic expeditions from 2018 to 2022 revealed the presence of multiple ECs, including perfluorooctanoic acid (PFOA), caffeine, pharmaceuticals and personal care products (PPCPs), and UV filters. Complementarily, a preliminary suspect screening via high-resolution mass spectrometry was attempted, revealing the potential presence of a broader spectrum of drugs, PPCPs, and lifestyle-related compounds in all studied species. This work represents one of the first applications of a QuEChERS-based analytical framework for ECs detection in Antarctic marine fauna, offering a reliable approach for long-term contaminant monitoring in one of the planet's most fragile ecosystems.

Iron is an essential element that can be growth-limiting in microbial communities, particularly those present within host organisms. To acquire iron, many bacteria secrete siderophores, secondary metabolites that chelate ferric iron. These iron chelates can be transported back into the cell via TonB-dependent transporters in the outer membrane, followed by intracellular liberation of the iron. Pathogenic Escherichia coli and Salmonella produce siderophores during gut infection. In response to iron starvation, the human gut symbiont Bacteroides thetaiotaomicron upregulates an iron piracy system, XusABC, which steals iron-bound siderophores from the invading pathogens. Here, we investigated the molecular details of xenosiderophore uptake across the outer membrane by the XusAB complex. Our crystal and cryogenic electron microscopy structures explain how the XusB lipoprotein recognizes iron-bound xenosiderophores and passes them on to the XusA TonB-dependent transporter. Moreover, we show that Xus homologues can transport a variety of siderophores with different iron-chelating functional groups.