Search Results (104)

Sea ice parameters are crucial for polar ship design. During China’s 39th Antarctic Scientific Expedition, ice condition from the entire navigation process of the research vessel Xuelong 2 was recorded using shipborne cameras. To obtain sea ice parameters, two deep learning models, Ice-Deeplab and U-Net, were employed to automatically obtain sea ice concentration (SIC) and sea ice thickness (SIT), providing high-frequency data at 5-min intervals. During the observation period, ice navigation accounted for 32 days, constituting less than 20% of the total 163 voyage days. Notably, 63% of the navigation was in ice fields with less than 10% concentration, while only 18.9% occurred in packed ice (concentration > 90%) or level ice regions. SIT ranges from 100 cm to 234 cm and follows a normal distribution. The results demonstrate that, to achieve enhanced navigation efficiency and fulfill expedition objectives, the research vessel substantially reduced duration in high-concentration ice areas. Additionally, the results of SIC extracted from shipborne camera images were compared with the data from the Copernicus Marine Environment Monitoring Service (CMEMS) satellite remote sensing. In summary, the sea ice parameter data obtained from shipborne camera images offer high spatial and temporal resolution, making them more suitable for engineering applications in establishing sea ice environmental parameters. Full article

Immunotherapy is a transformative strategy in oncology, yet the development of novel immunomodulatory agents remains essential. This study explores the anti-tumor potential of a structurally unique polysaccharide isolated from an Aspergillus ochraceus (AOP), sourced from the Antarctic Weddell Sea. Using alkaline-assisted extraction and chromatographic purification, we obtained a homogeneous polysaccharide predominantly composed of galactose and mannose, with an average molecular weight of 39.67 kDa. The structure was characterized by an integrated nuclear magnetic resonance spectroscopy and mass spectrometry analysis, revealing that the AOP is composed of β (1→5)-linked galactofuranose units, with a minor substitution by α-D-mannopyranose residues via (1→2) glycosidic bonds at the C2 of the galactofuranose. Functional assays, including CCK8 and wound-healing tests, demonstrated that this polysaccharide, referred to as AOP, inhibited melanoma cell proliferation and migration in a dose-dependent manner. Additionally, the AOP activated RAW264.7 and bone marrow-derived macrophage (BMDM) cells without exhibiting significant cytotoxicity, leading to the release of inflammatory factors such as TNF-α, IL-1β, and IL-6. Mechanistically, the AOP was found to upregulate the expression of CD86 and IFN-γ, while downregulating genes like IL-4 and Arg1. These findings position the AOP as the first documented Antarctic fungal polysaccharide with macrophage-reprogramming capabilities against melanoma, offering novel molecular insights for marine-derived immunotherapeutics. Full article

The search for life beyond Earth currently hinges on the detection of biosignatures that are indicative of current or past life, with terrestrial life being the sole known example. Deoxyribonucleic acid (DNA), which acts as the long-term storage of genetic information in all known organisms, is considered a biosignature of life. Techniques like the Polymerase Chain Reaction (PCR) are particularly useful as they allow for the amplification of DNA fragments, allowing the detection of even trace amounts of genetic material. This study aimed to detect DNA extracted from colonies of an Antarctic black fungus both when (i) alone and (ii) mixed with a Sulfatic Mars Regolith Simulant (S-MRS), after exposure to increasing doses of Fe ions (up to 1 kGy). PCR-based amplification methods were used for detection. The findings of this study revealed no DNA amplification in samples mixed with Sulfatic Mars Regolith Simulant, providing important insights into the potential application of these techniques for in situ DNA detection during future space exploration missions or for their application on the Mars sample return program; it also gives input in the planetary protection discussions. Full article

Soil health is essential for maintaining ecosystem balance, food security, and human well-being. Anthropogenic activities, such as climate change and excessive agrochemical use, have led to the degradation of soil ecosystems worldwide. Microbiome transplantation has emerged as a promising approach for restoring perturbed soils; however, direct soil transfer presents practical limitations for large-scale applications. An alternative strategy involves extracting microbial communities through soil washing processes, but its success highly depends on proper microbiota characterization and efficient extraction methods. This study evaluated a soil wash method using four different dispersant solutions (Tween-80, NaCl, sodium citrate, and sodium pyrophosphate) for their ability to extract the majority of microbial cells from Antarctic and Crop soils. The extracted microbiomes were analyzed using 16S rRNA gene metataxonomics to assess their diversity and abundance. We found that some treatments extracted a greater proportion of specific taxa, and, on the other hand, some extracted a lower proportion than the control treatment. In addition, these dispersant solutions showed the extraction of the relevant microbial community profile in soil samples, composed of multiple taxa, including beneficial bacteria for soil health. Our study aims to optimize DNA extraction methods for microbiome analyses and to explore the use of this technique in various biotechnological applications. The results provide insights into the effect of dispersant solutions on microbiome extractions. In this regard, sodium chloride could be optimal for Antarctic soils, while sodium citrate is suggested for the Crop soils. Full article

A multiscale sample entropy (MSE) algorithm is presented as a time domain feature extraction method to study the vocal behavior of blue whales through continuous acoustic monitoring. Additionally, MSE is applied to the Gaussian mixture model (GMM) for blue whale call detection and classification. The performance of the proposed MSE-GMM algorithm is experimentally assessed and benchmarked against traditional methods, including principal component analysis (PCA), wavelet-based feature (WF) extraction, and dynamic mode decomposition (DMD), all combined with the GMM. This study utilizes recorded data from the Antarctic open source library. To improve the accuracy of classification models, a GMM-based feature selection method is proposed, which evaluates both positively and negatively correlated features while considering inter-feature correlations. The proposed method demonstrates enhanced performance over conventional PCA-GMM, DMD-GMM, and WF-GMM methods, achieving higher accuracy and lower error rates when classifying the non-stationary and complex vocalizations of blue whales. Full article

Depsides and their derivatives are a class of polyketides predominantly found in fungal extracts. Herein, a silent nonreducing polyketide synthase (TalsA)-containing gene cluster, which was identified from the Antarctic sponge-derived fungus Talaromyces sp. HDN1820200, was successfully activated through heterologous expression in Aspergillus nidulans. This activation led to the production of two novel depsides, talaronic acid A (1) and B (2), alongside three known compounds (3–5). The further co-expression of TalsA with the decarboxylase (TalsF) demonstrated that it could convert 2 into its decarboxylated derivative 1. The structural elucidation of these compounds was achieved using comprehensive 1D and 2D-NMR spectroscopy, which was complemented by HR-MS analysis. Talaronic acids A and B were firstly reported heterodimers of 3-methylorsellinic acid (3-MOA) and 5-methylorsellinic acid (5-MOA). All isolated compounds (1–5) were tested for their anti-inflammatory potential. Notably, compounds 1 and 2 exhibited anti-inflammatory activity comparable to that of the positive control. These results further enrich the structural class of depside natural products. Full article

Lichens are an important source of diverse and unique secondary metabolites with recognized biological activities through experimental and computational procedures. The objective of this study is to investigate the metabolomic profile of the ethanolic extract of the Antarctic lichen Gondwania regalis and evaluate its antioxidant and antidiabetic activities with in vitro, in silico, and molecular dynamics simulations. Twenty-one compounds were tentatively identified for the first time using UHPLC/ESI/QToF/MS in negative mode. For antioxidant activity, the DPPH assay showed an IC₅₀ value of 2246.149 µg/mL; the total phenolic content was 31.9 mg GAE/g, the ORAC assay was 13.463 µmol Trolox/g, and the FRAP assay revealed 6.802 µmol Trolox/g. Regarding antidiabetic activity, enzyme inhibition yielded IC₅₀ values of 326.4513 µg/mL for pancreatic lipase, 19.49 µg/mL for α-glucosidase, and 585.216 µg/mL for α-amylase. Molecular docking identified sekikaic acid as the most promising compound, with strong binding affinities to catalytic sites, while molecular dynamics confirmed its stability and interactions. Toxicological and pharmacokinetic analyses supported its drug-like potential without significant risks. These findings suggest that the ethanolic extract of Gondwania regalis is a promising source of bioactive compounds for developing natural antioxidant and antidiabetic therapies. Full article

Cancer remains a leading cause of death worldwide, highlighting the urgent need for novel and more effective treatments. Natural products, with their structural diversity, represent a valuable source for the discovery of anticancer compounds. In this study, we screened 750 Antarctic extracts to identify potential inhibitors of human topoisomerase 1 (hTOP1), a key enzyme in DNA replication and repair, and a target of cancer therapies. Bioassay-guided fractionation led to the identification of palmitic acid (PA) as the active compound from the Antarctic sponge Artemisina plumosa, selectively inhibiting hTOP1. Our results demonstrate that PA irreversibly blocks hTOP1-mediated DNA relaxation and specifically inhibits the DNA religation step of the enzyme’s catalytic cycle. Unlike other fatty acids, PA exhibited unique specificity, which we confirmed through comparisons with linoleic acid. Molecular dynamics simulations and binding assays further suggest that PA interacts with hTOP1-DNA complexes, enhancing the inhibitory effect in the presence of camptothecin (CPT). These findings identify PA as a hTOP1 inhibitor with potential therapeutic implications, offering a distinct mechanism of action that could complement existing cancer therapies. Full article

Antarctic true-color imagery synthesized using multispectral remote sensing data is effective in reflecting sea ice conditions, which is crucial for monitoring. Deep learning has been explored for sea ice extraction, but traditional convolutional neural network models are constrained by a limited perceptual field, making it difficult to obtain global contextual information from remote sensing images. A novel model named GEFU-Net, a modification of U-Net, is presented. The self-established graph reconstruction module is employed to convert features into graph data and construct the adjacency matrix using a global adaptive average similarity threshold. Graph convolutional networks are utilized to aggregate the features at each pixel, enabling the rapid capture of global context, enhancing the semantic richness of the features, and improving the accuracy of sea ice extraction through graph reconstruction. Experimental results using the sea ice dataset of the Ross Sea in the Antarctic, produced by Sentinel-2, demonstrate that our GEFU-Net achieves the best performance compared to other commonly used segmentation models. Specifically, it achieves an accuracy of 97.52%, an Intersection over Union of 95.66%, and an F1-Score of 97.78%. Additionally, fewer model parameters and good inference speed are demonstrated, indicating strong potential for practical ice mapping applications. Full article

Antarctic soil represents an important reservoir of filamentous fungi (FF) species with the ability to produce novel bioactive lipids. However, the lipid extraction method is still a bottleneck. The objective of the present work was to isolate and identify cultivable FF from Antarctic soils, to assess the most effective methods for fatty acid (FA) extraction, and to characterise the obtained lipids. A total of 18 fungal strains belonging to the Botrytis, Cladosporium, Cylindrobasidium, Mortierella, Penicillium, Pseudogymnoascus, and Talaromyces genera and the Melanommataceae family were isolated and identified. The Folch, Bligh and Dyer, and Lewis extraction methods were assessed, and methyl esters of FA (FAMEs) were obtained. The Lewis method was the best in recovering FAMEs from fungal biomass. A total of 17 FAs were identified, and their chemical compositions varied depending on fungal species and strain. Oleic, linoleic, stearic, and palmitic acids were predominant for all fungal strains in the three assessed methods. Among the analysed strains, Cylindrobasidium eucalypti, Penicillium miczynskii, P. virgatum, and Pseudogymnoascus pannorum produced high amounts of FA. This suggests that the soils of Antarctica Bay, as well as harbouring known oleaginous fungi, are also an important source of oleaginous filamentous fungi that remain poorly analysed. Full article

In Antarctica, SAR interferometry has largely been used in coastal glacial areas, while in rare cases this method has been used on the Antarctic plateau. In this paper, the authors present a digital elevation and ice flow map based on SAR interferometry for an area encompassing Talos Dome (TD) and the Frontier Mountain (FM) meteorite site in North Victoria Land/Antarctica. A digital elevation model (DEM) was calculated using a double SAR interferometry method. The DEM of the region was calculated by extracting approximately 100 control points from the Reference Elevation Model of Antarctica (REMA). The two DEMs differ slightly in some areas, probably due to the penetration of the SAR-C band signal into the cold firn. The largest differences are found in the western area of TD, where the radar penetration is more pronounced and fits well with the layer structures calculated by the georadar and the snow accumulation observations. By differentiating a 70-day interferogram with the calculated DEM, a displacement interferogram was calculated that represents the ice dynamics. The resulting ice flow pattern clearly shows the catchment areas of the Priestley and Rennick Glaciers as well as the ice flow from the west towards Wilkes Basin. The ice velocity field was analysed in the area of FM. This area has become well known due to the search for meteorites. The velocity field in combination with the calculated DEM confirms the generally accepted theories about the accumulation of meteorites over the Antarctic Plateau. Full article

The waters around the western Antarctic Peninsula are experiencing fast warming due to global change, being among the most affected regions on the planet. This polar area is home to a large and rich community of benthic marine invertebrates, such as sponges, tunicates, corals, and many other animals. Among the sponges, the bright yellow Dendrilla antarctica is commonly known for using secondary diterpenoids as a defensive mechanism against local potential predators. From the dichloromethane extract of sponge samples from Deception Island collected in January 2023, we isolated a novel derivative with an unusual β-lactone diterpene skeleton here named dendrillolactone (1), along with seven previously described diterpenes, including deceptionin (2), a gracilane norditerpene (3), cadlinolide C (4), a glaciolane norditerpene (5), membranolide (6), aplysulphurin (7), and tetrahydroaplysulphurine-1 (8). Here, we also report our studies on the changes in the chemical arsenal of this sponge by slow temperature increase in aquaria experiments. Despite being a species capable of inhabiting volcanically active areas, with frequent water temperature fluctuations due to the existing fumaroles, the results show that diterpenes such as deceptionin, cadlinolide C, membranolide, and tetrahydroaplysulphurin-1 seem to be susceptible to the temperature increase, resulting in a trend to higher concentrations. However, temperatures above 4 °C severely affected sponge metabolism, causing its death much earlier than expected. Further research on the roles of these natural products in D. antarctica and their relationship to the sponge’s resilience to environmental changes should help to better understand the defensive mechanisms of Antarctic marine benthos in the context of global change. Full article

Ground-based detection of spaceborne dynamic objects, such as near-Earth asteroids and space debris, is essential for ensuring the safety of space operations. This paper presents YOLO-Dynamic, a novel detection algorithm aimed at addressing the limitations of existing models, particularly in complex environments and small-object detection. The proposed algorithm introduces two newly designed modules: the SC_Block_C2f and the LASF_Neck. SC_Block_C2f, developed in this study, integrates StarNet and Convolutional Gated Linear Unit (CGLU) operations, improving small-object recognition and feature extraction. Meanwhile, LASF_Neck employs a lightweight multi-scale architecture for optimized feature fusion and faster detection. The YOLO-Dynamic algorithm’s performance was validated on real-world images captured at Antarctic observatory sites. Compared to the baseline YOLOv8s model, YOLO-Dynamic achieved a 7% increase in mAP@0.5 and a 10.3% improvement in mAP@0.5:0.95. Additionally, the number of parameters was reduced by 1.48 M, and floating-point operations decreased by 3.8 G. These results confirm that YOLO-Dynamic not only delivers superior detection accuracy but also maintains computational efficiency, making it well suited for real-world applications requiring reliable and efficient spaceborne object detection. Full article

Lake ice phenology serves as a sensitive indicator of climate change in the lake-rich Northeast China. In this study, the freeze-up date (FUD), break-up date (BUD), and ice cover duration (ICD) of 31 lakes were extracted from a time series of the land water surface temperature (LWST) derived from the combined MOD11A1 and MYD11A1 products for the hydrological years 2001 to 2021. Our analysis showed a high correlation between the ice phenology measures derived by our study and those provided by hydrological records (R² of 0.89) and public datasets (R² > 0.7). There was a notable coherence in lake ice phenology in Northeast China, with a trend in later freeze-up (0.21 days/year) and earlier break-up (0.19 days/year) dates, resulting in shorter ice cover duration (0.50 days/year). The lake ice phenology of freshwater lakes exhibited a faster rate of change compared to saltwater lakes during the period from HY2001 to HY2020. We used redundancy analysis and correlation analysis to study the relationships between the LWST and lake ice phenology with various influencing factors, including lake properties, local climate factors, and atmospheric circulation. Solar radiation, latitude, and air temperature were found to be the primary factors. The FUD was more closely related to lake characteristics, while the BUD was linked to local climate factors. The large-scale oscillations were found to influence the changes in lake ice phenology via the coupled influence of air temperature and precipitation. The Antarctic Oscillation and North Atlantic Oscillation correlate more with LWST in winter, and the Arctic Oscillation correlates more with the ICD. Full article

Antarctic yeasts represent a poorly explored source of novel bioactive compounds with antineoplastic activity and a favorable toxicological profile. The present paper presents the newest data on the antiproliferative and antimicrobial potential of extracts obtained from the psychrophilic strain AL₁₀₃ of the species Sporobolomyces roseus. The capacity of AL₁₀₃ to grow under different cultivation conditions, including in a bioreactor system with optimal biomass quantities of approximately 6.0 g/L, was demonstrated. A comparative examination of the metabolic profiles (GC-MS-based) of yeast extracts revealed a wide variety of synthesized molecules responsible for the different levels of antineoplastic activity depending on the tissue origin of the malignant cell lines. Concentration response curves were generated by the MTT dye reduction test. The respective IC₅₀ values were extrapolated and found between 35.3 and 163 µg/mL. The antibacterial potential of both extracts was evaluated with the broth microdilution test against four referent pathogenic bacterial strains. The estimated minimal inhibitory concentrations revealed a moderate antibacterial activity. According to the GC-MS results, both extracts are rich in long-chain fatty acids which are known for their antibacterial properties. In conclusion, the Antarctic strain AL₁₀₃ possesses promising potential for further pharmacological investigations aiming to elucidate its application as a health-promoting food additive or/and as a source of biologically active compounds. Full article