Search Results (237)

Background/Objectives: Chemosymbiotic bivalves play a fundamental role in deep-sea cold seep and hydrothermal vent ecosystems, where essential long-chain polyunsaturated fatty acids (LC-PUFAs) are scarce. Whether these bivalves retain the capacity for endogenous PUFA synthesis remains poorly understood. Here, we investigated the PUFA biosynthetic capacity of two dominant chemosymbiotic bivalves from the Haima cold seep—the mussel Gigantidas haimaensis and the clam Archivesica marissinica. Methods: Genome and transcriptome assembly revealed three fatty acid desaturase (Fad) genes per species, which phylogenetically clustered into Δ5 (GhFads1, GhFads2; AmFads1, AmFads2) and Δ6/8 (GhFads3, AmFads3) clades, with lineage-specific duplications within the Δ5 clade. Functional assays were performed in yeast to characterize the activity of these enzymes. Results:Both Fads3 enzymes (Δ6/8 clade) convert C20:3n-6 and C20:4n-3 into C20:4n-6 and C20:5n-3, respectively, exhibiting Δ8-desaturase activity. Notably, Δ5-clade isoforms showed divergent substrate specificities: GhFads2 and AmFads1 functioned as classical Δ5-desaturases on PUFA substrates, whereas GhFads1 and AmFads2 specifically desaturated the bacterial monounsaturated fatty acid (MUFA) C18:1n-7 to produce C18:2n PUFAs. Conclusions: Together, our results reveal that cold-seep bivalves retain endogenous LC-PUFA biosynthetic capacity and have evolved duplicated Δ5-desaturases with novel regioselectivity toward bacterial MUFAs, likely representing an adaptive membrane modification for survival under extreme deep-sea conditions. Full article

Members of the class Campylobacteria are microaerophilic bacteria widely distributed across diverse environments and are abundant in hydrothermal systems. However, cultivated representatives, particularly from shallow-water vents, remain limited. Here, we investigated the genomic diversity and environmental adaptation of the genus Sulfurospirillum. Phylogenomic analysis revealed a clear separation between terrestrial and marine clades, with relatively few cultured representatives in the marine lineage. Strain 1307, isolated from shallow-water hydrothermal vents, expands the genomic representation of this underexplored clade. Pan-genome analyses based on complete genomes revealed an open pan-genome, indicating ongoing diversification of genus Sulfurospirillum. Further comparison between hydrothermal vent (HTV) and non-HTV lineages identified distinct adaptive features. Vent-associated strains are enriched in genes involved in sulfur metabolism, carbon fixation, the glycine cleavage system (GCS), and the biosynthesis of key cofactors (spermidine, thiamine, lipoate, and heme), reflecting metabolic adaptation to hydrothermal environments. Beyond well-established processes such as sulfur metabolism and autotrophic carbon fixation, the widespread presence of the GCS in vent-associated lineages suggests its potential role as an auxiliary carbon fixation pathway under anaerobic conditions. Overall, this study expands the phylogenetic and genomic diversity of Sulfurospirillum and offers new insights into the mechanisms underlying environmental adaptation and niche differentiation in vent-associated Campylobacteria. Full article

Shallow-water hydrothermal systems in active volcanic arcs serve as natural analogs for geothermal reservoir characterization and potential sources of Critical Raw Materials (CRMs). This study examines the Panarea hydrothermal system (Aeolian Islands, Tyrrhenian Sea, 37–207 m depth) to characterize its mineralogical facies and assess CRM enrichment patterns. Sixteen sediment samples collected during 2013–2015 research cruises were analyzed using SEM-EDS, XRPD with Rietveld refinement, and XRF. Four hydrothermal alteration facies were identified: (i) a low-temperature iron oxide facies dominated by nanocrystalline goethite with enrichments in As, V, and Mo; (ii) an argillic to propylitic facies containing smectite-group clays and high-temperature silica polymorphs, consistent with alteration at 200–350 °C; (iii) a phyllic to propylitic facies showing exceptional Ba enrichment (up to 46,976 ppm) and base-metal sulfide accumulations; and (iv) an advanced argillic facies including the first documented aluminophosphate–sulfate mineral at Panarea, a svanbergite–woodhouseite solid solution. Vanadium concentrations at Panarea exceed values reported across the Tyrrhenian–Aeolian domain, ranking this site among the highest-V shallow hydrothermal fields in the Mediterranean. These findings support a genetic model involving fault-controlled seawater circulation, magmatic CO₂ input, and episodic redox fluctuations, providing baseline data for CRM cycling and geothermal evaluation in Mediterranean submarine volcanic systems. Full article

Our concept of where life can thrive on Earth has advanced over the past 70 years to include extreme ionizing radiation, high temperatures, the deep subsurface, hydrothermal vents on the deep ocean floor, extreme arid deserts, and the ice-covered lakes and high mountain valleys of Antarctica. This expanding understanding of the biosphere has coincided with the development of space exploration programs, and it has informed those programs with regard to the search for life on other water worlds in our Solar System—especially Mars, Europa, and Enceladus. Titan presents a reverse of this approach. The interesting organic solids and fluids on that world have no analog in Earth habitability but have inspired suggestions of possible biological systems unlike any on Earth. If realized, the discovery of life on Titan would stretch the concept of habitability just as it stretches the concept of life as we know it. Habitability studies on exoplanets may follow both of these paths: we will look for habitability on exoplanets based on observed habitats on Earth, and we will also use observations of exoplanets as grist for contemplation of lifestyles different from anything we know on Earth. Full article

Seafloor hydrothermal systems at mid-ocean ridges are focal points for heat and matter exchange between the seawater and lithosphere. While seafloor seismographs (OBS) and pressure recorders (BPR) are standard for regional monitoring, achieving high-precision, vertical sub-surface data in complex hydrothermal terrains remains a significant technical objective. This study presents a novel in situ penetration probe designed for multi-parameter monitoring of marine hydrothermal vent areas. A key innovation of this work is its operational versatility and engineering efficiency: the probe is specifically designed for post-drilling deployment in boreholes, effectively utilizing existing coring sites to achieve direct coupling with the deep-seated crust, or for targeted placement via Remotely Operated Vehicles (ROVs). The device integrates a titanium-alloy conical tip and cylindrical chamber, housing tri-axial accelerometers and dual temperature-pressure sensors. Numerical simulations using the SST k-ω turbulence model and finite element analysis optimized the cone aperture and assessed fluid–structure stability under deep-sea conditions. Laboratory vibration tests and shallow-water sea trials validated the probe’s basic dynamic response, electromechanical integrity, and capability to acquire coupled environmental parameters. This compact, modular design provides a scalable and cost-effective framework for precise three-dimensional observation of sub-surface hydrothermal processes and deep-sea resource exploration. Full article

Submarine volcanic-hosted iron oxide deposits are critical archives for reconstructing the interplay between hydrothermal activities and marine redox conditions, yet the genesis of these deposits remains controversial. Here, we present a comprehensive geochronological and geochemical study on the Shikebutai iron deposit in the Western Tianshan, northwestern China, to constrain the mineralization age, the source of iron, and deposit genesis. The stratiform-to-lenticular orebodies are hosted within the Late Carboniferous marine volcanic–sedimentary sequence of the Yishijilike Formation. The iron ores consist primarily of hematite and quartz, with minor siderite and barite, exhibiting massive to locally banded textures. SHRIMP zircon U-Pb dating of the overlying andesite yields an age of 315.8 ± 1.5 Ma, consistent with the Sm–Nd isochron age of the iron ore samples (319 ± 26 Ma), precisely constraining the mineralization age to the Late Carboniferous (ca. 315–320 Ma). The geochemical compositions of the iron ore samples indicate negligible syn-depositional detrital contamination, as evidenced by low Al₂O₃ (<1.00 wt%) and TiO₂ (<0.20 wt%) contents. Low abundances of trace elements, including Sr (0.33–31.18 ppm), Hf (0.05–1.77 ppm) and Rb (1.49–39.02 ppm), further support the minimal detrital influence. Geochemical signatures, such as pronounced positive Eu anomalies (Eu/Eu = 1.62–7.12, mean 4.14), LREE enrichment ((La/Yb) _(PAAS) = 0.58–4.78), and near-chondritic Y/Ho ratios (mean 28.5), suggest a significant high-temperature (>250 °C) hydrothermal contribution. Moreover, the ε_Nd(t) values of iron ore samples (+1.99 to +2.93) are comparable to those of coeval andesites (+2.75 to +3.44) but exceed those of associated metasiltstones (+0.41 to +0.95), suggesting that ore-forming materials were derived from hydrothermal fluids leaching juvenile crust. The Shikebutai iron deposit exhibits geochemical and mineralogical similarities to modern Red Sea and East Pacific Rise metalliferous sediments, establishing the deposit as a product of active vent-proximal hydrothermal systems rather than marine chemical sediments such as banded iron formations. Full article

Viruses are abundant and widespread in extreme marine environments, such as sea ice, hydrothermal vents, and ocean trenches. They occur at temperatures up to 122 °C and down to −30 °C and pressures exceeding 100 MPa. Their distribution in these environments is closely correlated with that of their extremophile hosts, which are mostly bacteria, archaea, and microeukaryotes. Viruses have been shown to be capable of long-term survival in conditions simulating interstellar conditions. However, for them to reproduce, they would still need a host. Many recent astro-biological investigations have focused on habitability, specifically the ability of a planet to support the activity of at least one lifeform. The most likely candidates for extraterrestrial habitability in our solar system are the sea ice moons of Jupiter and Saturn, namely Europa and Enceladus. These are both thought to contain subsurface oceans of liquid water and potentially access to the necessary elements for microbial growth. If microorganisms were to be detected in these extraterrestrial environments, viruses might also be found coexisting with their host cells. Full article

The origin of life is, to the best of our knowledge, impossible to imagine without the formation of complex prebiotic biomolecules such as RNA, DNA, proteins and lipids. Lipids play a crucial role in the spontaneous formation of cell membranes, which are responsible for cell integrity, compartmentalization, selective permeability, and providing a microenvironment for biochemical reactions. The goal of the current work is to summarize the current state of the art regarding the abiotic formation of membrane building blocks, such as glycerol, fatty acids, and their phosphorylated version as phospholipid precursors. We describe the necessity of a systems chemistry approach for the complexification and expansion of the prebiotic network, enabling the formation of several membranogenic precursors. We also discuss prebiotic pathways for phosphorylation and acylation that could lead to phospholipid availability in hydrothermal environments and on the early Earth surface. We conclude with the possible spontaneous vesiculation of these molecules as a primitive version of the cell membrane. Thus, we present a comprehensive perspective on prebiotic vesicle formation, starting from simple molecules and developing until the self-assembly of vesicles. Full article

Studies of deep-sea hydrothermal vent systems have generated a spectrum of hypotheses concerning the origin of life on Earth. The present paper integrates recent literature surrounding three separate hydrothermal vent systems (Lost City in the mid-Atlantic, Guaymas Basin in the Gulf of California, and 9°50′ N on the East Pacific Rise) to provide biological, chemical, and geophysical support for these origin-of-life hypotheses. Comparisons between deep-sea hydrothermal vents and impact-generated hydrothermal vent systems may provide further insights into the origin of life. Impact-generated hydrothermal vent systems may have cradled early life. A comprehensive review of studies conducted at Lonar Lake, the Haughton impact structure, and the Chicxulub impact crater provide evidence of long-term hydrothermal activity conducive to the formation of early life, as well as potentially unique DNA structures found in sediment samples—opening the discussion for further investigations into the possible origin (or origins) of life both on Earth and other planetary bodies. Full article

The deep sea is often depicted as a barren environment. Using the abyssal plain as a baseline system characterized by high pressure, extreme nutrient limitation, and slow growth rates, this review contrasts these conditions with specialized habitats that serve as oases of life such as whale falls, cold seeps, and hydrothermal vents. These environments retain the high-pressure characteristic of deep-sea habitats, but other unique environmental factors select for organisms with distinct life-history strategies and growth rates. This review examines the environmental constraints, organism physiological adaptations, and life-history strategies that define each habitat. Through synthesizing these factors, we identify patterns that influence not only growth and succession, but broader ecosystem vulnerability and resilience, defined here as the capacity of these communities to recover from disturbance. By evaluating how biological traits contribute to resilience across the four habitats in response to specific environmental constraints, this comparative framework identifies trade-offs between growth specialization and habitat stability. Understanding these environmental factors is critical in evaluating the resilience of these habitats to growing anthropogenic disturbances and determining future directions of study. This review concludes that while hydrostatic pressure and temperature impose fundamental metabolic constraints, nutrient availability and habitat stability are the primary determinants of organismal growth rates and life-history strategies. In the context of each ecosystem, both these variables can play a large role in the ability and time to recover from disturbance and may be good indicators of resilience at both a community and an organismal level. Consequently, slow-growing, long-lived fauna may possess far lower intrinsic resilience to anthropogenic disturbance compared to rapidly growing organisms with shorter life histories. Varying resilience of these habitats may necessitate habitat-specific strategies for assessment and protection. Full article

Deep-sea hydrothermal vent fauna is often regarded as highly endemic, although exceptions have been reported. We examined genetic connectivity across broad spatial scales within the alvinocaridid genus Rimicaris, which has undergone substantial adaptive radiation worldwide. We analyzed six Rimicaris species using three genetic markers, cytochrome c oxidase subunit I (COI), 16S ribosomal rRNA gene (16S), and histone h3 (H3), and complete mitogenomes, employing newly generated sequences combined with publicly available sequence data. A genetic tree and haplotype networks were constructed, and divergence analyses were performed. Three clades of paired Rimicaris species were identified, each made up of taxa from different oceanic regions but showing relatively low COI divergence (0.35–1.90%). In Clade I, Rimicaris chacei and Rimicaris hybisae are morphologically similar and exhibit bidirectional gene flow, implying a dispersal route between the Mid-Atlantic Ridge (MAR) and the Mid-Cayman Spreading Center (MCSC). In Clade II, Rimicaris exoculata and Rimicaris kairei are morphologically, genetically, and ecologically distinct, reflecting restricted connectivity between the MAR and the Carlsberg Ridge (CR)–Central Indian Ridge (CIR). In Clade III, Rimicaris variabilis and Rimicaris cf. variabilis differ in nutritional strategies, showing a unidirectional dispersal route from the CIR to the southwestern Pacific (SWP), but morphological data to distinguish them are currently lacking. Some Rimicaris lineages maintain connectivity across distinct oceanic regions while others still form unique regional populations. This finding highlights the need for conservation strategies that incorporate both global-scale connectivity and regional endemism, rather than treating individual vent ecosystems as a single homogeneous management unit. Full article

Macellicephaloides Uschakov, 1955 (Annelida: Polynoidae) is a genus of deep-sea polychaetes characterized by a specialized pharynx bearing two pairs of jaws (with the dorsal pair fused) and three pairs of lateral papillae, the middle pair of which is greatly elongated, and remarkable adaptability to diverse deep-sea habitats. Most species in this genus inhabit abyssal depths (>7200 m), with high diversity in western Pacific trenches, while a few occur in relatively shallow habitats such as deep-sea seamounts and hydrothermal vents. This paper presents a new species, Macellicephaloides lingshuiensis sp. nov., found in deep-sea cold seeps in the South China Sea, representing the shallowest distribution record for the genus to date and the first record from cold seep environments. The classification and phylogeny of Macellicephaloides and related genera have long been the subject of debate. A previous study suggested that Macellicephaloides is nested within the Macellicephala clade, but our analyses—based on 13 mitochondrial protein-coding genes, 12S, 16S, 18S, 28S rRNA, and ITS1-ITS2 sequences—tentatively indicate that these two genera form independent evolutionary clades. Additionally, our phylogeny indicates a close evolutionary relationship between deep-sea Macellicephaloides and cave-dwelling polynoids (e.g., Gesiella), highlighting ecological connections between deep-sea and cave habitats. These conclusions are supported by morphological comparisons and genetic distance analyses. Although the subfamily Macellicephalinae is recovered as a monophyletic group, intergeneric phylogenetic relationships within it remain unresolved, highlighting the need for additional data from more species and genera. We amend the generic diagnosis of Macellicephaloides and provide an identification key to all valid species in the genus. This study clarifies the taxonomy and phylogeny of Macellicephaloides and related taxa, emphasizing the importance of continued sampling in understudied deep-sea habitats to enhance our understanding of their biodiversity. Full article

Proteases play key roles in many industrial processes and account for the majority of global enzyme sales. Geobacillus isolates from extreme environments such as marine hydrothermal vents are capable of producing high yields of proteases with thermophilic properties. Many proteases produced by Geobacillus species have been extensively studied, some of which have been purified and characterized. In addition, the high thermal stability largely depends on structural stability. Based on X-ray crystallography, several factors have been found to affect the structural stability of the thermostable proteases of Geobacillus. Moreover, the thermostable proteases of Geobacillus have a wide range of biotechnological applications, such as in detergent, food, bioremediation, leather-processing and textile industries. Therefore, this review focusses on the thermostable proteases of Geobacillus, including their characteristics, structural stability mechanisms and biotechnological applications. It will help the development of utilizing thermostable protease resources and enhancing their suitability for use in various industrial applications. Full article

Hydrothermal vents, widely occurring along middle-ocean ridges and volcanic arcs, have been well-studied in vent-associated microbiology, mineralogy, and geochemistry. However, there are rarely investigations regarding the detailed microbial community in the hydrothermal vent-influenced sediment. To explore hydrothermal activities on microbial diversity at the Carlsberg Ridge in the northwestern Indian Ocean, four sediment cores were sampled from the near-vent fields to distant vent sedimentary fields in the Tianxiu hydrothermal field, and the microbial community compositions were analyzed. The sediment microorganisms closest to the hydrothermal vent were primarily composed of Acidimicrobiia, Gammaproteobacteria, Anaerolineae, and Planctomycetes. The microbial communities at the depth containing extensive signals of hydrothermal activity consisted mainly of Dehalococcoidia, Aerophoria, Anaerolineae, and Gammaproteobacteria. No significant differences in microbial composition were observed between the two weak hydrothermal sediment cores, primarily composed of Nitrososphaeria, Gammaproteobacteria, Alphaproteobacteria, and Acidimicrobiia. Moreover, heterogeneous selection substantially impacted the bacterial community assembly in near-vent sediments other than stochasticity. Multivariate statistical analysis identified that environmental fluctuations accounted for 55.59% of the community variation, with hydrothermal inputs (such as Fe, Pb, Cu, and Zn) being the primary factors shaping the construction of hydrothermal sediment microbial communities. These results enhance understanding of the response of deep-sea sediments to hydrothermal activity. Full article

The Hugushan banded iron formation (BIF) is one of the most representative iron ore deposits in the central part of the North China Craton, and its ore formation mechanism remains highly controversial. This study presents whole-rock and Fe–Si–O isotope geochemical evidence, offering a new perspective on the ore formation mechanism of the Hugushan BIFs. The samples from the upper and lower parts of the Hugushan BIFs are characterized by slight enrichment of heavy and light Fe isotopes, respectively. Additionally, the samples from the upper part of the Hugushan BIFs show characteristics of slightly positive Ce anomalies and negative La anomalies, suggesting that the shallow ancient seawater was in a partially oxidized state, whereas the deep seawater remained in a reductive environment during the depositional period. The low Al₂O₃ and TiO₂ concentrations, as well as the depletion of Zr and Hf in the Hugushan BIFs, suggest that the contribution of terrestrial detrital materials to deposition is extremely limited. The BIFs all exhibit positive Eu anomalies, and the quartz in the BIFs is depleted in ³⁰Si, a characteristic similar to that observed in siliceous rocks formed in hydrothermal vent environments and during hydrothermal plume activity. Additionally, the δ¹⁸O values of quartz in Hugushan BIFs are similar to the O isotope compositions of hydrothermal sedimentary siliceous rocks, further suggesting that the silicon in BIFs originates primarily from seafloor hydrothermal activity. The combination of Eu/Sm, Sm/Yb, and Y/Ho ratios indicates that the major components (iron and silica) of the Hugushan Iron Ore Deposit originated from the mixing of high-temperature hydrothermal fluids with seawater, with the hydrothermal fluid contributing slightly less than 0.1%. The magnetite and quartz bands in the BIFs exhibit inhomogeneous and covariant δ⁵⁶Fe and δ³⁰Si isotope characteristics, suggesting that the alternating siliceous and ferruginous layers are products of original chemical deposition in the ocean. Periodic hydrothermal activity and ocean transgression caused the recurring deposition of siliceous and ferruginous layers, resulting in the characteristic banded structure of the Hugushan Iron Ore Deposit. Full article