Search Results (1,202)

Antarctic terrestrial photosynthetic biota is dominated by cryptogamic communities, which are largely restricted to scarce ice-free areas. Among these, nunataks constitute habitats of remarkable biogeographical interest, as they may harbor distinctive biotic assemblages worthy of investigation. This work presents a comprehensive assessment of lichen diversity on Antarctic nunataks. The lichen flora of four nunataks on the Hurd Peninsula (Livingston Island, maritime Antarctica) was investigated. Specimens were identified using an integrative approach combining morphological assessment and DNA barcoding. This survey revealed a high and potentially underestimated species richness, with 39 confidently identified and several additional taxa requiring further taxonomic resolution. A review of published records of lichen occurrence in nunatak and non-nunatak environments throughout Antarctica was used to evaluate patterns in taxonomic, biogeographical, and morphotype composition. This synthesis showed that nunataks support lower species richness than other ice-free environments. Most of their taxa occur in non-nunatak areas, consistent with patterns observed locally on the Hurd Peninsula. Floristic overlap seems greater in continental Antarctica, suggesting a stronger influence of nunatak-associated environmental constraints in the maritime region. These results underscore the ecological significance of nunataks as environmentally filtered habitats and highlight their relevance for understanding biodiversity patterns and community assembly in Antarctica’s terrestrial ecosystems. Full article

This study addressed the issue of insufficient activity in CALB lipase during the catalytic synthesis of key chiral intermediates for moxifloxacin. A structure-guided protein engineering strategy was employed to systematically modify its functional domains. Through molecular dynamics simulations of CALB-I189K, multiple regions exhibiting high conformational flexibility were preliminarily identified. Subsequently, by integrating 3D structural alignment with active site pocket distance analysis, the functionally most critical region (143–146) was selected. A site-directed saturation mutation library was constructed specifically targeting this region. Building upon the previously reported CALB-I189K, a mutant I189K/L144R/A146K was ultimately obtained through high-throughput screening combined with chiral HPLC validation. This mutant maintains excellent stereoselectivity (E = 206.52) while enhancing catalytic efficiency (k_cat/Κ_m) to 273.73 min⁻¹·mM⁻¹, approximately 4.5-fold that of I189K. At a substrate concentration of 1 M, it achieves 50% conversion within 2.6 h, demonstrating kinetic resolution capabilities approaching industrial standards. Molecular simulation analysis indicates that the L144R and A146K mutations synergistically enhance catalytic performance primarily by optimizing spatial distances between catalytic residues. This study not only provides a high-performance catalyst for the efficient biosynthesis of moxifloxacin chiral intermediates but also offers new insights for enzyme rational design based on dynamic structural information. Full article

Antarctica’s extreme cryospheric conditions impose severe thermodynamic constraints on the natural attenuation of hydrocarbon pollutants. Despite the Antarctic Treaty System’s protections, the footprint of human logistics has left persistent reservoirs of petroleum hydrocarbons that threaten endemic biodiversity. This review critically synthesizes the state-of-the-art in Antarctic bioremediation, moving beyond traditional culture-dependent studies to integrate recent multi-omics breakthroughs (2020–2025). We analyze the molecular mechanisms limiting bioavailability in frozen soils and highlight the adaptive strategies of psychrophilic consortia, including the modification of membrane fluidity and the expression of cold-active enzymes (e.g., RHDs, AlkB). Notably, we discuss emerging findings on novel long-chain alkane degradation genes (almA, ladA) identified in 2025, which challenge previous assumptions about recalcitrance. Furthermore, the review evaluates the engineering bottlenecks of in situ versus ex situ strategies, emphasizing the synergistic potential of bacterial–fungal co-cultures and the ecological necessity of “climate-smart” remediation to mitigate methane emissions from thawing permafrost. By bridging the gap between fundamental microbial genetics and applied field engineering, we propose a roadmap for the next generation of biotechnological solutions in the warming polar environment. Full article

The actinobacterial strain DEC002 was isolated recently from volcanic soils of Deception Island. Its taxonomic identity was resolved through a polyphasic strategy integrating morphology, physiological profiling, multilocus phylogeny, and genome-wide comparisons to resolve its identity. Concatenated core gene trees together with average nucleotide identity and digital DNA–DNA hybridization values place DEC002 within Actinacidiphila fildesensis with robust support. This is the first molecular confirmation of the species beyond King George Island and secures a second verified locality within the South Shetland Archipelago. Growth at low temperature with tolerance to moderate salinity indicates a psychrotolerant lifestyle. Cell-free supernatants inhibited representatives of foodborne Gram-negative and Gram-positive bacteria, including representatives of Enterobacteriaceae, Vibrio, Staphylococcus and Streptococcus. Genome analysis revealed enrichment in multiple biosynthetic gene clusters for nonribosomal peptides, polyketides, terpenes, and ribosomally synthesized and post-translationally modified peptides (RiPPs), supporting the biosynthetic potential of the strain. Functional annotations emphasize replication and repair modules, mobile element-associated proteins, helix–turn–helix regulators, and versatile transport systems, features coherent with cold stress and oligotrophic soils. Antibiotic susceptibility assays indicate a broad resistance phenotype under the experimental conditions tested, together with extracellular antimicrobial activity. These data refine the biogeography of A. fildesensis and indicate DEC002 as a credible Antarctic source of specialized metabolites with antimicrobial promise. Full article

The monophyletic lineage Phytoptidae s. str. (Acariformes, Eriophyoidea) comprises ~75 described species in 17 genera associated with angiosperms. Since the last keys to the world genera of Eriophyoidea were published in 2003, five new phytoptid genera have been described: Neoprothrix (Reis & Navia 2014), Borassia Chetverikov, Craemer 2017, Solenoplatilobus Chetverikov & Craemer 2016, Solenocristus Chetverikov et al. 2018, and Calventer Chetverikov 2025. Here, we provide an updated generic key for the tribe Sierraphytoptini (Phytoptidae), describe a new genus Nothofagicola, propose a new combination N. nothofagalis n. comb. (Chetverikov et al. 2018) (transferred from Solenocristus), report the first findings of N. cf nothofagalis from Nothofagus pumilio and No. antarctica from Southern Chile and describe three new species of Nothofagicola collected in Central Chile from stems of three Nothofagus species (Fagales: Nothofagaceae): N. alpinae n. sp. from No. alpina, N. bicristata n. sp. from No. alessandrii, and N. licanteniensis n. sp. from No. glauca. We also provide a corrigendum to our previous paper and state that the correct accession numbers for mitogenomic sequences of Leipothrix aegopodiae and L. cf knautiae are OR268621 and OR268622, respectively (vice versa in the paper). Full article

Dryopidae (Insecta: Coleoptera) comprise 37 genera and about 280 species, occurring on all continents except Antarctica. The Neotropical fauna of the family has been neglected for decades, despite a few recent contributions. So far, seven genera and 29 species have been recorded from Brazil. Based on 369 adults collected in the Brazilian states of Bahia, Paraná, and Rio de Janeiro, we describe Dryops antonioi sp. nov., D. nelsimarae sp. nov., and D. simoneae sp. nov. Furthermore, we herein redescribe and provide new records for D. ovatus (Grouvelle, 1890), an updated key to the species recorded from the country and a checklist of Neotropical representatives of the genus. Full article

Raphidiopsis raciborskii is one of the most widely reported cyanobacteria worldwide, responsible for dense blooms and cyanotoxin production. Classified as invasive, it has been documented across all continents except Antarctica. While its distribution has been extensively studied, abiotic factors have consistently emerged as the main determinants of its success, which are therefore the focus of the present study. The objective of the present review is to synthesize findings from both experimental and field-based studies to identify which are the key drivers of its dominance. In total, 30 abiotic factors were reported, reflecting the broad strategies of the species. Results show the temperature as a consistent universal factor (11–35 °C), while differences were found regarding nutrient dynamics. Particularly, nitrogen forms and N/P ratios predominated in field-based evidence, whereas photosynthetically active radiation was disproportionately emphasized within experimental studies under controlled conditions. Factors such as salinity and micronutrients, and synergistic interactions remain critically understudied, limiting predictive capacity under global change scenarios. Understanding which combinations of these drivers create favorable conditions is essential for anticipating bloom dynamics in order to establish management strategies for avoiding or mitigating the negative impact of them. Full article

Submarine canyon-channel systems play a critical role as potential conduits for warm-water upwelling around Antarctica, potentially influencing ice-sheet stability. Integrating multibeam bathymetry, seismic profiles, and morphometric analysis, this study identifies 29 canyon-channel systems along the Adélie Land margin and reveals clear morphological contrasts between the Adélie Depression and the Adélie Bank. Systems in the Depression are elongated, slightly sinuous, and dendritic, with downstream increases in width-to-depth ratio, whereas those on the Bank are shorter, isolated, and single-branched, with irregular along-thalweg variations. Mann–Whitney U tests show significant differences in sinuosity and thalweg gradient (p < 0.01). These contrasts reflect the combined effects of shelf-slope topography, sediment supply, and ice-sheet dynamics. In the Depression, steep slopes, focused glacial sediment input from the Wilkes Subglacial Basin, and associated progradational wedges and mass transport deposits promote mass failures and turbidity-current incision. Strong correlations among canyon-channel length, width, and depth indicate coherent scaling under concentrated sediment supply. In contrast, gentler slopes and lower sediment input on the Bank produce simpler systems. These results highlight how glaciated-margin canyon morphology records coupled sedimentary and ice-sheet–ocean processes. Full article

During warm intervals such as the Early Eocene, megathermal vegetation belts expanded toward higher latitudes, displacing mesothermal and microthermal biota. Here, we examine the diversity and paleoclimate of the Early Eocene Ligorio Márquez Formation (LMF) in the context of other Paleogene Patagonian palynofloras, and we model the potential distribution of Nothofagus using Early Eocene climate simulations. From 35 processed samples, 20 yielded palynomorphs and 85 morphospecies were distinguished. We hypothesize that species richness in the LMF is comparable to other Eocene microfloras, and that climate models will confirm mesothermal conditions for this formation while identifying western Gondwana as the primary region of climatic suitability for Nothofagus. Our results indicate that the LMF hosted a diverse flora under mesothermal, humid-temperate conditions (Köppen–Geiger climate Cfa, within the broader Cf no-dry-season regime). Ecological niche modeling further indicates that western Gondwana (South America, the Antarctic Peninsula, New Zealand, and Australia) provided broadly suitable climatic conditions for Nothofagus. In Experiment 1 (modern-to-Eocene transfer), Maxnet models showed high discriminatory power (AUC_test = 0.86–0.88) with low omission at P10 (OR_P10 = 0.099–0.128). In Experiment 2 (Eocene-to-Eocene calibration), performance was consistently high across GCMs (AUC_test = 0.87–0.98; OR_P10 = 0.091–0.182). However, conditions across Antarctica were likely challenging, limiting its effectiveness as a dispersal corridor during the Eocene. Finally, our results suggest that the ancient South Pacific High influenced the northern distributional limit of Nothofagus in South America. Full article

Background: The number of people working in Antarctica has steadily increased. Identifying the characteristic functional changes in polar expeditioners can help preserve health, enhance work capacity, and improve adaptive potential in specific environments. Objective: This study aimed to evaluate the impact of a short-term (30-day) expedition in Antarctica on selected physiological parameters among expedition participants, depending on their body mass index (BMI). Methods: Thirty-four expedition members, divided into 3 BMI groups, were examined before and after a one-month stay in Antarctica. The assessments included anthropometry, body composition analysis, blood pressure (BP) evaluation, and a cycle ergometer stress test, performed up to 85% of predicted maximal heart rate (PWC85%) with gas analyses and heart rate measured at the 3rd minute after exercise completion (HR3’), used as an indicator of cardiovascular recovery. Results: After the expedition, the participants with normal weight showed a modest but significant increase in body weight and BMI, and non-significant increases in fat mass (FM) and muscle mass (MM); cardiovascular recovery and physical working capacity were improved, while aerobic fitness remained unchanged. In the overweight group, post-expedition body weight and BMI did not change significantly, although small reductions in FM and improvements in MM, BP, PWC85%, and HR3’ were observed. Returning, the participants with obesity demonstrated non-significant improvements in body composition and modest declines in BP, together with a significant improvement in HR3’. Conclusions: Comparative analysis revealed significant differences in post-expedition changes in several functional parameters between the normal-weight and obese groups. Overall, the Antarctic expedition elicited beneficial cardiovascular and functional adaptations, particularly among overweight individuals, while body composition and aerobic capacity remained unchanged across all groups. Full article

In this study, we compared the bacterial diversity of two independent snow and ice sampling campaigns conducted in 2015–2016 and 2018–2019 at Dome C, Concordia Station, Antarctica. Using 16S rRNA gene amplicon sequencing, we analysed 81 samples and, after quality filtering and rarefaction, obtained approximately 3.8 million high-quality reads. Alpha diversity analyses revealed comparable richness between the two sampling periods, while community evenness was higher in 2018–2019. In contrast, all beta diversity metrics consistently showed significant differences in community composition between years, while beta dispersion analyses indicated distinct levels of heterogeneity within the year. The results of the Raup-Crick null model (R0) analyses showed that the observed differences did not deviate from random expectations under the applied null hypothesis. Overall, these results indicate pronounced interannual variability in bacterial assemblages at Concordia Station and suggest that temporal changes in community composition are consistent with assembly processes dominated by episodic inputs and limited persistence under extreme environmental conditions. This study implements previous investigations by providing a comparative temporal perspective and contributes to a better understanding of microbial dynamics in one of the most isolated and low-biomass environments on Earth. Full article

Pegmatites with miarolitic cavities have not previously been reported from the Larsemann Hills, East Antarctica, and their age and origin remain poorly constrained. We report the first geochemical and geochronological data for fluorapatite from a newly discovered pegmatite with miarolitic cavities in the Larsemann Hills. Large Fe-rich fluorapatite crystals (up to 5 cm) contain abundant oriented monazite-(Ce) inclusions and display elevated REE (1397–7966 ppm), relatively high Y (945–4192 ppm), and low Sr (52.2–83.5 ppm). Their trace-element signatures plot within the fields of partial melts, high-grade metamorphic rocks, and evolved fluid-rich magmatic systems. U–Pb dating of fluorapatite yields concordant ages of 519 ± 4 Ma (ID-TIMS) and 521 ± 31 Ma (LA-ICP-MS), indicating crystallization during the D₄ stage of the Pan-African orogeny. The isotopic equilibrium between apatite and monazite inclusions suggests synchronous formation and late-stage fluid overprinting. Combined geological, geochemical, and isotopic evidence shows that the pegmatite formed in situ as a product of anatexis of the Broknes paragneisses and evolved within a volatile-rich magmatic–hydrothermal system. These results provide the first direct age constraints on pegmatites with miarolitic cavities in Antarctica and shed new light on the final stages of East Gondwana assembly. Full article

Future contributions to sea level rise from the Antarctic Ice Sheet due to climate change remain one of the largest uncertainties for future sea level. Improving predictions of ice mass loss is a major goal of numerical ice sheet models, but a major difficulty is that ice sheet models assume an empirical fit to modern-day observed speeds to infer sliding parameters. While this results in accurate modern-day comparisons, predictions for future or past climates that have substantially different conditions will be inaccurate if the empirical sliding law used is not appropriate. To help constrain which basal physics is most appropriate and therefore which basal parameterizations should be used in ice sheet models, here, we pursue an understanding of which physical mechanisms are most likely to explain the spatial variability in flowline speeds throughout the Antarctic Ice Sheet. Specifically, we compare observed flowline surface speeds with predictions of speeds from internal ice deformation and Weertman sliding using a conservative range of physical parameters. Despite large uncertainties, we find a number of flowlines where the predictions can be distinguished from each other and one can infer that one of the two mechanisms, or a third mechanism, Coulomb frictional failure, may likely be principally responsible. Geographic patterns in the dominant mechanism are observed. Weertman sliding appears dominant in several flowline clusters in East Antarctica, and there are regional consistencies in the estimated nearness to flotation at locations of inferred initiation of Coulomb failure. Weertman sliding at faster rates is also observed within regions of inferred Coulomb failure, consistent with theoretical expectations. The key finding that the dominant deformation mechanism varies along and between Antarctic flowlines may complicate how ice sheet models need to be parameterized if accurate predictions of future ice loss and sea level rise are to be accurate. Full article

Parasitism affects nearly half of all animal species and strongly influences ecosystem dynamics. Despite their sentinel value, parasitic infections in cetaceans remain understudied. This study assessed the diversity, prevalence, and burden of gastrointestinal and pulmonary parasites in seventy-five stranded cetaceans from six species along the central and northern Portuguese coastline. Coprological methods included Mini-FLOTAC^®, Willis-flotation, natural sedimentation, modified Ziehl–Neelsen staining, direct immunofluorescence, and adapted spontaneous sedimentation. Overall, 61.3% of samples tested positive for at least one parasitic taxon, with 22.7% showing coinfections. Anisakidae and Ascaridida were the most prevalent (36%), followed by Pseudaliidae larvae (5.3%), unidentified trematode eggs (8.0%), Odhneriella spp. (5.3%), Nasitrema spp. (2.7%), Zalophotrema spp. (2.7%), and Synthesium spp. (1.3%). Nematode eggs exhibited the highest mean burden, with anisakids reaching 4862 eggs per gram of feces (EPG), whereas trematodes showed a markedly lower burden, exemplified by Zalophotrema spp. with 90 EPG. All samples assessed were negative for Cryptosporidium spp. and Giardia spp. Unidentified ovoid structures were present in 76% of samples. Macroscopic sedimentation revealed anisakid larvae, one cestode, over fifty Ogmogaster antarctica specimens, and six marine arthropods. These findings provide baseline data for cetacean parasitology and support future integrative research for conservation and ecosystem health. Full article

The Earth’s lithosphere, the rigid outermost layer of the planet, is composed of numerous tectonic plates of varying sizes that move over the underlying asthenosphere. The motion and interaction of these plates give rise to a wide range of geodynamic processes. Accurate monitoring of these processes is essential for maintaining a stable, up-to-date, and reliable terrestrial reference frame. This study investigates the horizontal and vertical motions of the Antarctic Plate resulting from its interactions with adjacent plates. Tectonic plate movements can be determined using several space-geodetic techniques, including Global Navigation Satellite Systems (GNSS), Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), and Interferometric Synthetic Aperture Radar (InSAR). Among these methods, GNSS is currently the most widely used, as plate motions can be derived from continuous observations recorded at permanent stations and processed using scientific or commercial software. Within the scope of this research, GNSS data collected between 2020 and 2023 were processed using the GAMIT/GLOBK V.10.7 software package to estimate the coordinates and velocities of stations located on the Antarctic, South American, African, and Australian Plates in the ITRF14 reference frame. Furthermore, plate-fixed solutions were generated to analyze the relative motion of the Antarctic Plate with respect to neighboring plates. The results indicate that the Antarctic Plate moves at an average velocity of approximately 4–18 mm/year in the ITRF14 frame. The plate diverges from both the African and Australian Plates and exhibits predominantly strike-slip motion relative to the South American Plate. A comparison with existing global plate motion models demonstrates that the obtained velocities are consistent within 0–5 mm/year. Full article