Search Results (107)

Objective: In this study, the heat shock transcription factor (HSF) gene family in Ganoderma lucidum was systematically characterized. Using genomic and transcriptomic data, we identified HSF family members and investigated their expression patterns under temperature stress and their potential regulatory roles in triterpenoid biosynthesis. Methods: A genome-wide identification of HSF genes in G. lucidum was performed using bioinformatic approaches. A phylogenetic tree was constructed, and conserved motifs, gene structures, and protein tertiary structures were predicted. The relative expression levels of HSF genes and key mevalonate (MVA) pathway enzyme genes were examined by a quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) in mycelia subjected to temperature stress. Total triterpenoid content in fermented mycelia under temperature stress was determined using the vanillin–glacial acetic acid method. Results: Eight HSF family members (GlHSF1–GlHSF8) were identified in G. lucidum. Phylogenetic analysis revealed that GlHSF proteins were closely related to PoHSF from Pleurotus ostreatus. Transcriptomic analysis showed that HSF genes exhibited relatively high expression levels during the mature stage while being barely expressed during the mycelial stage. Under heat stress (42 °C), most GlHSF genes peaked at 18 h, with GlHSF2 showing the most pronounced response (approximately 13-fold upregulation). Downstream MVA pathway genes, including IDI, PMK, and MVD, were significantly upregulated at 24 h, whereas the upstream rate-limiting enzyme gene HMGR was continuously suppressed. Despite HMGR suppression, total triterpenoid content did not decrease significantly, likely due to the activation of downstream genes. Under cold stress (14 °C), the expression of most GlHSF and MVA pathway genes decreased, accompanied by a significant reduction in total triterpenoid content. Conclusions: The HSF gene family was identified in the G. lucidum genome. Based on expression analysis, GlHSF2 showed the strongest response under heat stress, and its expression peak was correlated with the sequential activation of downstream genes in the MVA pathway. This suggests that GlHSF2 acts as a potential key regulatory node, differentially regulating upstream and downstream MVA pathway genes to influence triterpenoid biosynthesis under heat stress. These findings provide a theoretical basis for future research on the biological functions of GlHSF homeostasis. Full article

Neoproterozoic iron formations (NIFs), deposited during Cryogenian glaciation events, are critical for understanding early Earth oxidation events and the evolution of glacial–interglacial environments. Apatite, a common accessory mineral in iron formations, holds significant implications for sedimentary environments and diagenetic processes, but these aspects remain underexplored. This study focuses on the Hengyang NIF in the Nanhua Basin, South China. Using whole-rock geochemistry and major and trace element analysis of apatite, we investigate the environmental significance of apatite and associated diagenetic processes. Our results show that the Hengyang NIF are formed through the mixing of low-temperature hydrothermal fluids, seawater, and terrigenous detrital materials, with hydrothermal contributions increasing progressively from the bottom to the top of the iron formation layers. Whole-rock geochemical proxies indicate that the depositional water column evolved from relatively oxidizing to weakly oxidizing conditions. The study further demonstrates that the rare earth element patterns in apatite, characterized by middle rare earth element enrichment, are primarily controlled by porewater chemistry during diagenesis. In contrast, Ce anomalies and the V/Cr and V/(V + Ni) ratios in apatite, which are strongly influenced by fluid–rock interactions and magnetite recrystallization, no longer reliably reflect the primary depositional environment. The Th/U ratio in apatite, due to its geochemical stability, aligns with whole-rock trends and serves as a more reliable redox proxy. Based on these findings, we propose a three-stage depositional-diagenetic model: the early and late stages are characterized by high-energy, rapid sedimentation with minimal diagenetic modification, while the middle stage is dominated by low-energy, stagnant conditions with slow sedimentation rates, leading to prolonged diagenesis and significant decoupling of mineral geochemical signatures. This study emphasizes the need to distinguish between sedimentary and diagenetic signals when using mineral geochemical proxies to reconstruct paleoenvironments and provides new insights into the genesis of Neoproterozoic iron formations. Full article

The Neoproterozoic Paraguay Belt (western Brazil), formed by the Brasiliano/Pan-African Orogenic Cycle during Western Gondwana amalgamation, hosts tens of gold occurrences and deposits. This review provides new insights into the metallogeny and tectonics of the Paraguay Belt Gold Province, based on previous and new data on stratigraphy, structural geology, metamorphism, hydrothermal alteration, and gold grades. The mineralizations correspond to turbidite-hosted orogenic gold systems, with quartz veins cutting metasedimentary rocks with minor metavolcanics. A six-phase tectonic–metallogenic evolution model is proposed. The early stages correspond to glaciolacustrine deposition in a rift that evolved into a passive margin and then into a foreland basin, with glaciomarine sediments. Late sedimentation corresponds to glacial-to-post-glacial shallow marine units in the foreland. The orogeny progressed with cratonic collisions, resulting in three deformation (two compressional and one extensional) and three metamorphic (regional, dynamic, and contact) phases. The Au mineralization results from metamorphic fluids that transported metals from the metasedimentary pile and deposited them in reactive rocks (rich in magnetite or organic carbon). Gold occurs in sulfide-rich (pyrite and galena) veins and hydrothermal alteration zones. The metallotects and structural controls highlighted here are useful tools for prospecting gold in the Paraguay Belt and similar geological terranes. Full article

A typical Tamarix nebkha was studied in the southern Qaidam Basin, China. K-feldspar pIRIR dating was applied to establish a reliable chronological framework, and an Undatable age–depth model was constructed. Accumulation rates (AR) declined in stages: rapid (~1.33 cm/a; ~370–260 yr BP), slower (~0.75 cm/a; ~260–130 yr BP), and slowest (~0.31 cm/a; ~130 yr BP-present). This dynamic pattern is likely influenced by a combination of regional aeolian activity variations, geomorphological evolution, and the intrinsic growth dynamics of the nebkha itself. To further understand the relationship between nebkha development and climatic conditions, a δ¹³C sequence was reconstructed using Tamarix plant remains preserved within the sediments. Based on shifts in leaf-level δ¹³C values, which indicate changes in water use efficiency, water availability over the past 370 years was inferred and divided into three main phases: relatively sufficient from 1650 to 1690, gradually decreasing during 1690–1870, and increasing again after 1870. The δ¹³C trend closely correlates with temperature variations derived from δ¹⁸O records of the Malan ice core. This suggests that in this hyper-arid region, the development of Tamarix nebkhas is primarily controlled by glacial meltwater and snowmelt runoff from the Kunlun Mountains, rather than by local precipitation. Full article

Variance-driven decomposition based on the singular spectrum analysis of the European Project for Ice Coring in Antarctica (EPICA) δD, CO₂, and CH₄ records allowed a novel quantitative structural interpretation of all glacial/interglacial cycles and glacial terminations of the last 800 kyr. This bottom-up approach used the response components of EPICA stacked records to reconstruct the envelope of the thermal response through a physical interference model. The aim was to improve understanding of the intensity, amplitude, and asymmetry features of 73 marine isotope stages/substages (MISs) and seven glacial terminations. The Antarctic stack record can be described by a variance-weighted superposition of ten thermal waves of different origins (mid-term oscillation, orbitals, and suborbitals) that stochastically interfere at a given time according to their relative differences in frequency, amplitude, and polarity. Interglacial/glacial stages resulted from constructive interference and bipolar amplification of warming/cooling responses, respectively. The low-intensity MISs (including 90% of substages) and the unbiased-dated terminations fell in the low-interference regions, where dominant destructive patterns minimize the thermal envelope. The positive skewness of the EPICA stack resulted from constructive interference with a strong bias in the warming direction, especially after the Mid-Brunhes Event. Duration analysis of short eccentricity hemicycles exhibited an intrinsic unexpectedly prolonged mean cooling in the nominal solution (5.8 kyr) and its EPICA response as well (8.6 kyr), along with an interference-induced asymmetry (21.1 kyr). The overall effect has led to the saw-tooth shape of glacial cycles, which was strongly induced by interference. Full article

Benthic δ¹⁸O and δ¹³C values, as well as the mean grain size (MS) of sortable silt (SS), were used to construct the records of deep-water ventilation during the last 300 ka, at core GC02. This core is located at 4430 m water depth on the Madagascar basin near the Southwest Indian Ocean mid-ridge (SWIR). Decreased values of MS of SS reveal a weakened Antarctic Bottom Water (AABW) in the glacial periods, while increased values indicate enhanced AABW in the interglacial periods. The MS of SS record in GC02 exhibited a particularly good synchronization with a record based on the δ¹³C gradient between the North Atlantic and tropical Pacific Ocean, indicating that AABW is dominated by the overturning strength of the Atlantic meridional overturning circulation (AMOC), and showed a higher generation rate in the early stages of the glacial periods. A rapid reduction in δ¹³C occurred in MIS 2, 4, and 6; the MS values in GC02 and winter sea ice (WSI) also exhibited significant decreases and increases, respectively. By controlling the transport of ventilated water mass to deep waters and polar heat transport, in the Indian Ocean, both the change in AABW intensity and the Southern Ocean ice volume result from changes in the AMOC under the orbital modulation background. In the Southwest Indian Ocean, AMOC has a larger effect on ice volume during glacial periods, while its effect on AABW is relatively strong during interglacial periods. Full article

The increasing threat of Glacial Lake Outburst Floods (GLOFs), intensified by climate change, underscores the urgency for developing advanced early warning systems. The near-annual, cyclical outbursts of Lake Merzbacher in the Tien Shan mountains present a severe downstream threat, yet its remote location and lack of instrumentation pose a significant challenge to traditional monitoring. To bridge this gap, we develop and validate a dynamic risk assessment framework driven entirely by remote sensing data. Methodologically, the framework introduces an innovative Ice-Water Composite Index (IWCI) to resolve the challenge of lake area extraction under mixed ice-water conditions. This is coupled with a high-fidelity 5 m resolution Digital Elevation Model (DEM) of the lake basin, autonomously generated from GF-7 Dual-Line Camera (DLC) imagery, which enables accurate daily volume retrieval. Through systematic feature engineering, nine key hydro-thermal drivers are quantified from MODIS and other products to train a Random Forest (RF) machine learning model, establishing the non-linear relationship between catchment processes and lake volume. The model demonstrates robust predictive performance on an independent validation set (2023–2024) (R² = 0.80, RMSE = 5.15 × 10⁶ m³), accurately captures the complete lake-filling cycle from initiation to near-peak stage. Furthermore, feature importance analysis quantitatively confirms that Positive Accumulated Temperature (PAT) is the dominant physical mechanism governing the lake’s storage dynamics. This end-to-end framework offers a transferable paradigm for GLOF hazard management, enabling a critical shift from static, regional assessments to dynamic, site-specific early warning in data-scarce alpine regions. Full article

Salinization in the western Songnen Plain has limited regional ecology and land use for decades, with its primary cause closely tied to sediment transport. To elucidate sediment evolution and its role in soil salinization, a borehole from saline-alkali land in Taonan County, west of the Songnen Plain, was investigated within an AMS¹⁴C, OSL, and ESR dating framework. Grain size analysis, end-member modeling, and major-element geochemistry revealed four transport components—fluvial, aeolian, glacio-fluvial, and lacustrine. Five provenance stages from the late Early Pleistocene to the Early Holocene were found: (1) distal weathered volcanic rock transport with minor fluvial–alluvial input; (2) proximal alluvial–proluvial transport; (3) ice meltwater and wind-driven transport; (4) predominantly wind transport; and (5) renewed fluvial–proluvial transport. These shifts correspond to regional paleoclimate fluctuations driven by global ice volume cycles, which control sediment supply, hydrology, and consequently salt accumulation in warm humid periods and upward salt migration in cold dry periods. The findings of this study demonstrate that Pleistocene glacial–interglacial climate cycles are the dominant driver of sediment transport and salinization dynamics on the western Songnen Plain. Full article

A sedimentary profile consisting of blown sand capped by a sand-loam bedded interval was analysed in the Svätuše sand pit in the East Slovak Lowland. Stratigraphically, blown sands from this lowland have so far only been indirectly classified into the Weichselian glacial, mainly into its middle and upper stages. The age classification presented in this study results from the optically stimulated luminescence dating method. It identifies the blown sand from the Svätuše as originating during the Early Glacial and Early Pleniglacial phases of the Weichselian glacial (MIS 4–5d). At the end of the Early Glacial phase of the Weichselian glacial, palaeoenvironmental conditions changed. The deposition of blown sand became episodic rather than continuous. As a result, the analysed sedimentary record is composed of a sand-loam interbedded interval in the uppermost part. Full article

The Wushan Loess, situated in the Yangtze Three Gorges region of China, represents the southernmost aeolian loess deposit in China and provides critical insights into Late Pleistocene paleoenvironmental conditions and East Asian monsoon dynamics. Despite its significance, the genesis and provenance of this unique loess deposit remain controversial. This study employs an integrated multi-proxy approach combining detrital zircon U-Pb geochronology, optically stimulated luminescence (OSL) dating, and detailed grain size analysis to systematically investigate the provenance and depositional mechanisms of the Wushan Loess. Three representative loess–paleosol profiles (Gaotang-GT, Badong-BD, and Zigui-ZG) were analyzed, yielding 17 OSL ages, 729 grain size measurements, and approximately 420 analyses per profile were conducted, yielding 1189 valid ages (GT 406, BD 391, ZG 402). OSL chronology constrains the deposition period to 18–103 ka (Marine Isotope Stages 2–5), coinciding with enhanced East Asian winter monsoon activity during the Last Glacial period. Grain size analysis reveals a dominant silt fraction (modal size: 20–25 μm) characteristic of aeolian transport, with coarse silt (20–63 μm) averaging 47.1% and fine silt (<20 μm) averaging 44.2% of the sediments. Detrital zircon U-Pb age spectra exhibit consistent major peaks at 200–220 Ma, 450–500 Ma, 720–780 Ma, and 1800–1850 Ma across all profiles. Kernel Density Estimation (KDE) and Multi-Dimensional Scaling (MDS) analyses indicate a mixed provenance model. Non-negative least squares (NNLS) unmixing confirms this quantitative source apportionment., dominated by proximal contributions from the upper Yangtze River basin (including the Three Gorges area and Sichuan Basin, ~65%–70%), supplemented by distal dust input from the Loess Plateau and northern Chinese deserts (~30%–35%). This study establishes for the first time a proximal-dominated provenance model for the Wushan Loess, providing new evidence for understanding southern Chinese loess formation mechanisms and Late Pleistocene East Asian monsoon evolution. Full article

Reconstructing the deep water salinity during the Last Glacial Maximum (LGM, 26.5~19 ka BP), corresponding to Marine Isotope Stage 2, the most recent and coldest period, is crucial for understanding glacial deep ocean circulation variation and its effect on the climate. The South China Sea (SCS) is one of the largest marginal seas in the western Pacific Ocean, where LGM deep water salinity reconstruction remains unexplored. This study employs pore water [Cl⁻] profiles acquired from boreholes of Site U1499 of IODP Expedition 367 and Sites U1431 and U1433 of IODP Expedition 349 to reconstruct the LGM salinity in the deep SCS. Utilizing a one-dimensional diffusion-advection numerical model, the LGM salinity of the deep northern SCS is determined to be 35.68 ± 0.04 g/kg, and that of the deep central SCS is 35.61 ± 0.03 g/kg, revealing an intra-basin salinity gradient of ~0.07 g/kg. LGM salinity gradients within the SCS were reduced relative to modern ones, indicating attenuated deep circulation within the SCS during the LGM. Furthermore, a diminished salinity gradient (Δ = 0.02 g/kg) across the Luzon Strait between the SCS and Pacific and an enhanced vertical stratification between Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar Deep Water (LCDW) collectively support a sluggish deep Pacific circulation during the LGM. Full article

Atlas cedar (Cedrus atlantica (Endl.) Manetti ex Carrière) is an endemic and relict conifer species from northwestern Africa, relatively drought-tolerant but also highly sensitive to recurrent summer heat stress. Cedar forests have undergone a dramatic range contraction in recent decades. The development of effective conservation strategies requires long-term perspectives to understand how forests have responded to past disturbances. We present a multi-proxy, high-resolution analysis of a 122 cm-deep fossil record (Merj Lkhil; LKH) located at 1213 m a.s.l. in Jbel Bou Hachem (Moroccan Rif), providing insights into the fragmentation of cedar stands. Cedrus likely formed extensive lowland populations during the final stages of the Late Glacial and began migrating upslope during the Greenlandian. It reached its maximum extent in the Rif around 7000 cal yr BP. Thereafter, increasing aridity, enhanced seasonality, and growing anthropogenic pressure triggered its long-term decline. This trajectory involved a vertical reorganization of montane ecosystems, with Cedrus progressively retreating within mid- and low-elevation forests, while deciduous oaks maintained a long-term co-dominance and Q. ilex L. gradually expanded, especially at lower elevations. Today, Cedrus is confined to isolated high-elevation stands in Jbel Bou Hachem. These relic populations should be prioritized for conservation under ongoing climate and land-use change. Full article

The fossiliferous Dursunlu Lignite Quarry (DLQ) is highlighted prominently in the archeological and paleontological literature because of the study of Pleistocene fauna and lithic artifacts, being considered the oldest Paleolithic site in Türkiye. Although the fauna and flora assemblage from DLQ are reasonably well known, taxonomic studies devoted to some groups, such as ostracods, mollusks, reptiles, and amphibians, have never been carried out. Here, we describe, illustrate, and study the taxonomic composition and ecological implications of the unpublished material of said groups, together with the aquatic plants and fish, recovered from six samples taken from the palustrine and peat bog facies of the sedimentary sequence. In addition, the recovered charophytes and cyprinids refine our taxonomical knowledge of both aquatic plants and fish. Our results concur with previous paleoenvironmental inferences based on flora and fauna composition—with DLQ representing a very shallow eutrophic lake with a dense palustrine vegetation belt during the cold (glacial) stage of the late Early Pleistocene—as well as highlight the study of all available groups as pivotal for better understanding the paleolake biota. We further conclude that the wetland areas of Dursunlu and surrounding steppe areas appear to have been an excellent environment for sporadic settlement of hominins during the Early Pleistocene, given the availability of food resources and easy access to water. Full article

This work examines the occurrence of biological soil crusts (BSCs) on glacial foreland moraines and their relationship to other vegetative components of the post-glacial landscape. BSCs on moraines of all ages are biologically complex composites of cyanobacteria, mosses, lichens, liverworts, and fungi. The amount of surface cover by BSCs and other components of the successional communities vary approximately with the ages of the surfaces. During the pioneer successional stage, BSCs are more abundant than other community components and consist primarily of filamentous cyanobacteria. On the youngest moraines, vascular plants, with the exception of graminoids, occur exclusively where BSCs are present. On successively older moraines, the coverage by mosses and vascular plants generally increases while that of BSCs decreases, although substantial variations occur that are attributed to exposure to environmental factors, primarily wind. Overall successional patterns suggest an essential role of BSCs in facilitating vascular plant colonization mainly during the pioneer stage, likely through enhancement of soil moisture and nutrient availability. The importance of facilitation by BSCs appears to decrease on older moraines as BSCs are replaced or subsumed by vascular plants and mosses. Full article

The survival status of Lumnitzera littorea is near threatened globally and critically endangered in China. Clarifying its global distribution pattern and its changing trends under different future climate models is of great significance for the protection and restoration of its endangered status. To build a model for this purpose, this study selected 73 actual distribution points of Lumnitzera littorea worldwide, combined with 12 environmental factors, and simulated its potential suitable habitats in six periods: the Last Interglacial (130,000–115,000 years ago), the Last Glacial Maximum (27,000–19,000 years ago), the Mid-Holocene (6000 years ago), the present (1970–2000), and the future 2050s (2041–2060) and 2070s (2061–2080). The results show that the optimal model parameter combination is the regularization multiplier RM = 4.0 and the feature combination FC (Feature class) = L (Linear) + Q (Quadratic) + P (Product). The MaxEnt model has a low omission rate and a more concise model structure. The AUC values in each period are between 0.981 and 0.985, indicating relatively high prediction accuracy. Min temperature of the coldest month, mean diurnal range, clay content, precipitation of the warmest quarter, and elevation are the dominant environmental factors affecting its distribution. The environmental conditions for min temperature of the coldest month at ≥19.6 °C, mean diurnal range at <7.66 °C, clay content at 34.14%, precipitation of the warmest quarter at ≥570.04 mm, and elevation at >1.39 m are conducive to Lumnitzera littorea’s survival and distribution. The global potential distribution areas are located along coasts. Starting from the paleoclimate, the plant’s distribution has gradually expanded, and its adaptability has gradually improved. In China, the range of potential highly suitable habitats is relatively narrow. Hainan Island is the core potential habitat, but there are fragmented areas in regions such as Guangdong, Guangxi, and Taiwan. The modern centroid of Lumnitzera littorea is located at (109.81° E, 2.56° N), and it will shift to (108.44° E, 3.22° N) in the later stage of the high-emission scenario (2070s (SSP585)). Under global warming trends, it has a tendency to migrate to higher latitudes. The development of the aquaculture industry and human deforestation has damaged the habitats of Lumnitzera littorea, and its population size has been sharply and continuously decreasing. The breeding and renewal system has collapsed, seed abortion and seedling establishment failure are common, and genetic variation is too scarce. This may indicate why Lumnitzera littorea is near threatened globally and critically endangered in China. Therefore, the protection and restoration strategies we propose are as follows: strengthen the legislative guarantee and law enforcement supervision of the native distribution areas of Lumnitzera littorea, expanding its population size outside the native environment, and explore measures to improve its seed germination rate, systematically collecting and introducing foreign germplasm resources to increase its genetic diversity. Full article