Ecological risk assessment of landscape in arid area watersheds under ecological water conveyance: A case study of Taitema Lake.

The Taitema Lake Basin serves as an ecological barrier in the south of the Tarim Basin, connecting with the Qiemo, Ruoqiang, and Milan oases, collectively preventing the expansion and merging of the desert, specifically inhibiting the convergence of the Taklamakan Desert and Lop Nur. In recent years, with changes in the natural environment and an increase in water usage, the downstream flow of the Tarim River has decreased, leading to the gradual drying up of Taitema Lake and exacerbating desertification, resulting in frequent sandstorms. Subsequently, under the influence of ecological water transfer projects, Taitema Lake has gradually recovered, and the ecological environment has improved. This study focuses on Taitema Lake and its nearby regions, constructing the Regional Landscape Ecological Risk Index (ERI) to assess landscape ecological risks before and after ecological engineering and determine ecological benefits. The results indicate that the EWC (Ecological Water Conveyance) project effectively supplements water in the intermediate and lower courses of the Tarim River and the terminal lakes, significantly bolstering ecological conditions in the lake basin and reducing risks. However, the current EWC project is relatively extensive, and the water reaching the Tarim River and Taitema Lake depends entirely on the surplus water from upstream production and daily life. Additionally, the distribution of downstream water depends entirely on natural topography, leading to uneven spatiotemporal distribution of water resources and significant evaporation losses. Rational hydraulic engineering measures should be taken to re-plan the distribution of rivers and lakes, achieving the maximum ecological benefits of the EWC project.

Effect of Lignin Structure Characteristics on the Performance of Lignin Based Phenol Formaldehyde Adhesives.

As the second most abundant biopolymer, lignin remains underutilized in various industrial applications. Various forms of lignin generated from different methods affect its physical and chemical properties to a certain extent. To promote the broader commercial utilization of currently available industrial lignins, lignin sulfonate (SL), kraft lignin (KL), and organosolv lignin (OL) are utilized to partially replace phenol in the synthesis of phenol formaldehyde (PF) adhesives. The impact of lignin production process on the effectiveness of lignin-based phenolic (LPF) adhesives is examined based on the structural analysis of the selected industrial lignin. The results show that OL has more phenolic hydroxyl groups, lower molecular weight, and greater number of reactive sites than the other two types of lignins. The maximum replacement rate of phenol by OL reaches 70% w/w, resulting in organosolv lignin phenolic (OLPF) adhesives with a viscosity of 960 mPa·s, a minimal free formaldehyde content of 0.157%, and a shear strength of 1.84 MPa. It exhibits better performance compared with the other two types of lignin-based adhesives and meets the requirements of national standards.

Bioequivalence and Safety Assessment of 2 Formulations of Low-Dose Metformin Hydrochloride under Fasting Conditions in Healthy Chinese Participants: A Randomized Phase 1 Clinical Trial.

The incidence of type 2 diabetes is high, and the existing metformin hydrochloride (MH) tablets of 250 mg cannot meet the demands of the Chinese drug market. This study aimed to evaluate the bioequivalence and safety of generic formulations of MH tablets (test formulation [T], 250 mg/tablet) and innovative products (reference formulation [R], 250 mg/tablet) under fasting conditions. This was an open-label, single-dose, 2-period, 2-sequence crossover, single-center, randomized phase I clinical trial. T and R were considered bioequivalent if the adjusted geometric mean ratios (GMRs) and 90% confidence intervals of the area under the curve (AUC) and maximum concentration (Cmax ) were within the range of 0.8-1.25. Thirty-five participants completed the trial. The T/R adjusted GMRs (95.7% for Cmax , 98.7% for AUC0→t , 98.8% for AUC0→∞ ) were within the acceptable bioequivalence range of 80%-125%. No serious adverse events or suspected or unexpected serious adverse reactions occurred during this trial. The study findings confirmed that generic MH is a well-tolerated and bioequivalent alternative to innovative products under fasting conditions in healthy Chinese participants. (www.chinadrugtrials.org.cn; registration no. CTR20190356).

Green syntheses of silk fibroin/wool keratin-protected AuAg nanoclusters with enhanced fluorescence for multicolor and patterned anti-counterfeiting.

Counterfeiting is a serious worldwide issue that threatens human health and economic security. How to apply anti-counterfeiting techniques to textile materials remains a great challenge. Herein, we report bimetallic AuAg nanoclusters (NCs) synthesized by one-step reduction of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) with wool keratin (WK) as reducer and silk fibroin (SF) as stabilizer. The strongest orange-red fluorescence under ultraviolet light as well as the highest zeta potential absolute values of -27.97 mV were simultaneously realized in the optimal proportion Au-AgNCs2 (WK/SF is 3/2), which was further processed to a series of anti-counterfeiting films by blending with SF, silk sericin (SS), and polyvinyl alcohol (PVA). After successfully being numbered into fifteen colors, a dark blue-orange-dark red-dark blue cyclic fluorescent anti-counterfeiting color chart was designed. In addition, a two-Maxwell-unit model was constructed to assist with the microstructure analysis, which found that the formation of hydrogen bonds and the secondary structure transition from α-helices to ß-sheets during stretching were responsible for improving the mechanical properties and the two-staged fracture curves of films, respectively. Finally, a patterned and multicolor fluorescence anti-counterfeiting fabric application was demonstrated by combining the color chart and screen printing, indicating the great potential in textile anti-counterfeiting.

A nomogram based on clinical factors to predict calendar year readmission in patients with ulcerative colitis.

Background: Readmission shortly after discharge is indicative of an increased disease severity for patients with ulcerative colitis (UC) and ineffectiveness to medical therapy, which may contribute to a dismal prognosis. Objectives: This study aimed to explore prognostic variables with a nomogram to predict unplanned UC-related readmission within 1 year after discharge. Design: A retrospective cohort study. Methods: Electronic medical records of all UC patients treated at our center between 1 January 2014 and 31 June 2021 were reviewed. A comprehensive analysis of various characteristics, such as demographics, comorbidities, medical history, follow-up appointments, admission endoscopy, histopathologic features, etc., was used to determine the primary end point, which was unplanned UC-related calendar year readmission. Results: We found that the unplanned UC-related readmission rate within 1 year was 20.8%. In multivariable cox analysis, the predictors of the Elixhauser comorbidity index [Hazard ratio (HR): 3.50, 95% confidence interval (CI): 1.93-6.37], regular follow-up (HR: 0.29, 95% CI: 0.16-0.53), any history of corticosteroid use (HR: 3.38, 95% CI: 1.83-6.27), seral level of C-reactive protein (HR: 1.01, 95% CI: 1.00-1.02), and the UC endoscopic index of severity (HR: 1.29, 95% CI: 1.05-1.57) independently predicted calendar year readmission after discharge. The established nomogram had a consistently high accuracy in predicting calendar year readmission in the training cohort, with a concordance index of 0.784, 0.825, and 0.837 at 13, 26, and 52 weeks, respectively, which was validated in both the internal and external validation cohorts. Therefore, UC patients were divided into clinically low-, high-, and extremely high-risk groups for readmission, based on the calculated score of 272.5 and 378. Conclusion: The established nomogram showed good discrimination and calibration powers in predicting calendar year readmission in high-risk UC patients, who may need intensive treatment and regular outpatient visits.

EM-2, a natural sesquiterpene lactone from Elephantopus mollis H.B.K., enhanced the sensitivity of breast cancer cells to epirubicin by blocking protective autophagy.

BACKGROUND: EM-2, a natural sesquiterpene lactone isolated from Elephantopus mollis H.B.K., showed a good anti-breast cancer effect when combined with epirubicin (EPI). However, its synergistic sensitization mechanism remains unclear. PURPOSE: This study aimed to determine the therapeutic effect and possible synergistic mechanism of EM-2 with EPI in vivo and in vitro and to provide an experimental basis for the treatment of human breast cancer. METHODS: Cell proliferation was measured with MTT and colony formation assays. Apoptosis and reactive oxygen species (ROS) levels were examined through flow cytometry, and the expression levels of proteins related to apoptosis, autophagy, endoplasmic reticulum stress, and DNA damage were detected through Western blot analysis. Moreover, the caspase inhibitor Z-VAD-FMK, autophagy inhibitors bafilomycin A1 and chloroquine, ER stress inhibitor 4-phenylbutyric acid, and ROS scavenger N-acetyl cysteine were applied to verify signaling pathways. Breast cancer cell lines were used to evaluate the antitumor functions of EM-2 and EPI in vitro and in vivo. RESULTS: We demonstrated that in MDA-MB-231 and SKBR3 cells, the IC50 of EPI combined with EM-2 (IC20) was 37.909 and 33.889 times lower than that of EPI alone, respectively. Further study verified that in EPI-resistant lines (MDA-MB-231/EPI), the IC50 of EPI combined with EM-2 (IC20) was 26.305 times lower than that of EPI alone. Mechanistically, EM-2 could reverse the protective effect of EPI against autophagy in SKBR3 and MDA-MB-231 cells. EM-2 and EPI could trigger ER stress. When EM-2 and EPI were used in combination, ER stress was continuously activated, and ER stress-mediated apoptosis was induced. Meanwhile, EM-2 combined with EPI promoted DNA damage then induced apoptosis. In vivo, the volume of breast cancer xenografts in the combination group was smaller than that in the control, EM-2, and EPI groups. Immunohistochemical experiments demonstrated that the combination of EM-2 and EPI could block autophagy and promote ER stress in vivo. CONCLUSION: EM-2 enhances the sensitivity of MDA-MB-231, SKBR3, and EPI-resistant cells to EPI.

Knockdown of the SELENOK gene induces ferroptosis in cervical cancer cells.

Selenoprotein K (SELENOK) is one of the endoplasmic reticulum (ER) proteins that mainly functions in the regulation of ER stress, calcium flux, and antioxidant defense. Reactive oxygen species (ROS) is one of the key indicators of ferroptosis, and SELENOK inhibition could disrupt ROS balance, and consequently might cause ferroptosis. However, there are no previous studies about the mechanism of SELENOK in ferroptosis by regulating ROS. In this study, we report the effect of SELENOK inhibition on cell proliferation, viability, iron recycling-associated proteins, ROS, antioxidant enzymes, and lipid peroxidation of cervical cancer cells (HeLa cells). The results showed that ROS levels and iron-dependent lipid peroxidation were significantly enhanced, whereas cell viability and proliferation were significantly downregulated, and resulted in marked reductions in tumor size after SELENOK knockdown. SELENOK knockdown also caused steep decreases in glutathione peroxidase 4/glutathione levels and deterioration in ROS scavenging ability, and exacerbated ferroptosis in HeLa cells. Our findings elucidated that SELENOK knockdown could shrink tumor size by regulating ferroptosis, which might provide a theoretical basis for treating cervical cancer.

Borana rangeland of southern Ethiopia: Estimating biomass production and carrying capacity using field and remote sensing data.

Assessing rangeland productivity is critical to reduce ecological degradation and promote sustainable livestock management. Here, we estimated biomass productivity and carrying capacity dynamics in the Borana rangeland of southern Ethiopia by using field-based data and remote sensing data (i.e., normalized difference vegetation index (NDVI)). Data was collected from both rainy and dry seasons when biomass production was high and low respectively. Results of linear regression showed that both biomass production (R2 adj = 0.672) and NDVI value (R2 adj = 0.471) were significantly decreased from 1990 to 2019. Field data and NDVI values for mean annual biomass showed a significant linear relationship. The model accuracy in the annual relationship between the observed and predicted biomass values was strong (R2 adj = 0.986) but with high standard error, indicating that the observed biomass production in the rangeland area was not in good condition as compared with the predicted one. This study suggests that, using NDVI data and field-based data in combined way has high potential to estimate rangeland biomass and carrying capacity dynamics at extensively grazed arid and semi-arid rangelands. And to use for estimating stoking rates and predicting future management techniques for decision making.

Selenomethionine Improves Mitochondrial Function by Upregulating Mitochondrial Selenoprotein in a Model of Alzheimer's Disease.

Alzheimer's disease (AD), the most common neurodegenerative disease in elderly humans, is pathologically characterized by amyloid plaques and neurofibrillary tangles. Mitochondrial dysfunction that occurs in the early stages of AD, which includes dysfunction in mitochondrial generation and energy metabolism, is considered to be closely associated with AD pathology. Selenomethionine (Se-Met) has been reported to improve cognitive impairment and reduce amyloid plaques and neurofibrillary tangles in 3xTg-AD mice. Whether Se-Met can regulate mitochondrial dysfunction in an AD model during this process remains unknown.In this study, the N2a-APP695-Swedish (N2aSW) cell and 8-month-old 3xTg-AD mice were treated with Se-Met in vitro and in vivo. Our study showed that the numbers of mitochondria were increased after treatment with Se-Met. Se-Met treatment also significantly increased the levels of NRF1 and Mfn2, and decreased those of OPA1 and Drp1. In addition, the mitochondrial membrane potential was significantly increased, while the ROS levels and apoptosis rate were significantly decreased, in cells after treatment with Se-Met. The levels of ATP, complex IV, and Cyt c and the activity of complex V were all significantly increased. Furthermore, the expression level of SELENO O was increased after Se-Met treatment. Thus, Se-Met can maintain mitochondrial dynamic balance, promote mitochondrial fusion or division, restore mitochondrial membrane potential, promote mitochondrial energy metabolism, inhibit intracellular ROS generation, and reduce apoptosis. These effects are most likely mediated via upregulation of SELENO O. In summary, Se-Met improves mitochondrial function by upregulating mitochondrial selenoprotein in these AD models.

Selenoprotein K deficiency-induced apoptosis: A role for calpain and the ERS pathway.

Selenoprotein K (SELENOK), an endoplasmic reticulum (ER) resident protein, is regulated by dietary selenium and expressed at a relatively high level in neurons. SELENOK has been shown to participate in oxidation resistance, calcium (Ca2+) flux regulation, and the ER-associated degradation (ERAD) pathway in immune cells. However, its role in neurons has not been elucidated. Here, we demonstrated that SELENOK gene knockout markedly enhanced ER stress (ERS) and increased apoptosis in neurons. SELENOK gene knockout elicited intracellular Ca2+ flux and activated the m-calpain/caspase-12 cascade, thus inducing neuronal apoptosis both in vivo and in vitro. In addition, SELENOK knockout significantly reduced cognitive ability and increased anxiety in 7-month-old mice. Our findings reveal an unexpected role of SELENOK in regulating ERS-induced neuronal apoptosis.

Atherosclerotic lesion-specific copper delivery suppresses atherosclerosis in high-cholesterol-fed rabbits.

Dietary cholesterol supplements cause hypercholesterolemia and atherosclerosis along with a reduction of copper concentrations in the atherosclerotic wall in animal models. This study was to determine if target-specific copper delivery to the copper-deficient atherosclerotic wall can block the pathogenesis of atherosclerosis. Male New Zealand white rabbits, 10-weeks-old and averaged 2.0 kg, were fed a diet containing 1% (w/w) cholesterol or the same diet without cholesterol as control. Twelve weeks after the feeding, the animals were injected with copper-albumin microbubbles and subjected to ultrasound sonication specifically directed at the atherosclerotic lesions (Cu-MB-US) for target-specific copper delivery, twice a week for four weeks. This regiment was repeated 3 times with a gap of two weeks in between. Two weeks after the last treatment, the animals were harvested for analyses of serum and aortic pathological changes. Compared to controls, rabbits fed cholesterol-rich diet developed atherosclerotic lesion with a reduction in copper concentrations in the lesion tissue. Cu-MB-US treatment significantly increased copper concentrations in the lesion, and reduced the size of the lesion. Furthermore, copper repletion reduced the number of apoptotic cells as well as the content of cholesterol and phospholipids in the atherosclerotic lesion without a disturbance of the stability of the lesion. The results thus demonstrate that target-specific copper supplementation suppresses the progression of atherosclerosis at least in part through preventing endothelial cell death, thus reducing lipid infiltration in the atherosclerotic lesion.

Effect of Elevation on the Density and Species Composition of Encroacher Woody Plants in Borana Rangeland, Southern Ethiopia.

Woody plant encroachments are major concerns across the grasslands biome, while the patterns of individual species existence at a landscape level can be limited locally and regionally. The paper assesses the species composition, community structure, and density of individual and combined encroacher woody species in terms of tree equivalent per hectare (TE ha-1) within five different height classes at four elevation levels in Borana arid thorn bush savanna grasslands in Southern Ethiopia. At each elevation class, a grid of 20 × 20 m main plot was placed, and samples were collected randomly from three 100 m2 sub-plot within the main plot. Using a single-factor analysis of variance, the effects of four elevation classes were considered on encroacher woody plant species composition, total, and individual density (TE ha-1) within height classes. A total of 22 encroacher woody plant species composition were identified. The identified woody plants are seemingly a threat to the Borana rangelands of Southern Ethiopia with various patterns of distribution and density (TE ha-1) among the different elevation levels. Of the identified species, Acacia reficiens had the highest density (1052.22 ± 265.34 TE ha-1) at elevation level II. The most important encroaching species in each elevation level was varied considerably, while the combined woody plants density (TE ha-1) within height classes across elevation levels showed minimal variations. This suggests that the management of a specific ecological site might require greater focus in terms of the functional traits of individual woody species composition, density coverage within height classes, and community structure. Hence, identifying the patterns, distribution, and density of encroaching woody species is crucial for the control of key encroacher woody species at a landscape level.

Corrigendum: Selenomethionine Improves Mitochondrial Function by Upregulating Mitochondrial Selenoprotein in a Model of Alzheimer's Disease.

[This corrects the article DOI: 10.3389/fnagi.2021.750921.].

Lead exposure results in defective behavior as well as alteration of gut microbiota composition in flies and their offsprings.

BACKGROUND: Lead (Pb) has become one of the most dangerous metals to human health, especially to the nervous system as its persistent accumulation and high toxicity. However, how the gut microbiota influence the Pb-related neurotoxicity remains unclear. The aim of our study was to explore the link among Pb exposure, behavior changes, and gut microbiota. METHODS: Using Drosophila melanogaster as model, climbing assay, social avoidance, social space, and short-term memory analysis were preformed to study the behavioral changes in flies exposed to Pb and their offspring. 16S rRNA sequencing was used to explore the changes in the gut microbiota of the flies with/without Pb-exposure. RESULTS: The crawling ability, memory, and social interactions of Pb-exposed parent flies decreased significantly. For the offspring, behaviors were more significantly affected in male offspring whose male parent was exposed to Pb. The alpha diversity and the beta diversity of gut microbiota were significantly different between the Pb-exposed flies and the controls, as well as between the male offspring and the controls. Two genera, Lactobacillus and Bifidobacterium were found significantly decreased in the Pb-exposed flies when compared to the controls and significantly correlated with the learning and memory. Four genera, Bilophila, Coprococcus, Desulfovibrio, and Ruminococcus were found depleted in the female offspring of the Pb-exposed flies. CONCLUSIONS: Lead exposure resulted in defective behavior and alteration of gut microbiota composition in flies and their offspring, alteration in gut microbiota might be the link between behavioral changes induced by Pb-exposure.

Do Herbaceous Species Functional Groups Have a Uniform Pattern along an Elevation Gradient? The Case of a Semi-Arid Savanna Grasslands in Southern Ethiopia.

Knowledge of the total (overall) and individual herbaceous vegetation species relating to a distinctive site might help in the development of management strategies for a large number of threatened herbaceous species. This paper assesses the total and functional group herbaceous biomass, species richness, evenness, and diversity at four elevation classes in Borana rangelands of arid thorn bush savanna grasslands in Southern Ethiopia. At each elevation class, a grid of 20 × 20 m main plot was placed, and individual herbaceous species samples were collected randomly from five 1 m2 quadrants within the main plot. Using a single-factor analysis of variance (ANOVA), the effects of four elevation classes were considered on whole-vegetation, grasses, graminoid, and forb species diversity, evenness, richness, and biomass. A total of 49 herbaceous species were recorded. Of the total identified herbaceous species, three grass species and two graminoid species were found across all studied elevation classes, but the forb species did not overlap along the studied elevation classes. The total richness, diversity, and evenness of herbaceous species were considerable and significant along elevation classes. The grass, graminoid, and forb species richness, diversity, and evenness responded differently, and the functional group of species may be a good indicator of the community processes of grassland across elevation classes. The contribution of forb richness to the total richness was more pronounced than grass and graminoid, which indicates the shift of savanna grassland to grazing tolerant herbaceous species. The results suggest that the pooled data analysis of herbaceous vegetation community structure and biomass could obscure complicate trends of the functional group at elevation classes and for managing herbaceous species in savanna grasslands, the management models should focus on the functional group species composition, community structure, and biomass.

Rock magnetic and environmental magnetic data of lacustrine sediments from the Heqing basin.

This data article associated with the manuscript "Magnetic mineral dissolution recorded in a lacustrine sequence from the Heqing Basin, SW China, and its relationship with changes in the Indian monsoon". Through detailed rock magnetic measurements, magnetic properties of the lacustrine sediments (magnetic mineralogy, their concentration and domain state) were clarified. Then, analyzing the relationship between magnetic property and paleoenvironmental proxies can reveal the paleoenvironmental implications of magnetic parameters of lacustrine sediments from the Heqing basin. Comparing paleoenvironmental proxies of lacustrine sediments from the Heqing basin with proxies associated with Indian monsoon recorded in Arabian Sea, and Bay of Bengal, can deepen our understanding about the characteristics of Indian Monsoon in the geological time.

Monsoonal control on a delayed response of sedimentation to the 2008 Wenchuan earthquake.

Infrequent extreme events such as large earthquakes pose hazards and have lasting impacts on landscapes and biogeochemical cycles. Sediments provide valuable records of past events, but unambiguously identifying event deposits is challenging because of nonlinear sediment transport processes and poor age control. Here, we have been able to directly track the propagation of a tectonic signal into stratigraphy using reservoir sediments from before and after the 2008 Wenchuan earthquake. Cycles in magnetic susceptibility allow us to define a precise annual chronology and identify the timing and nature of the earthquake's sedimentary record. The grain size and Rb/Sr ratio of the sediments responded immediately to the earthquake. However, the changes were muted until 2 years after the event, when intense monsoonal runoff drove accumulation of coarser grains and lower Rb/Sr sediments. The delayed response provides insight into how climatic and tectonic agents interact to control sediment transfer and depositional processes.

The Effect of Consistency on Short-Term Memory for Scenes.

Which is more detectable, the change of a consistent or an inconsistent object in a scene? This question has been debated for decades. We noted that the change of objects in scenes might simultaneously be accompanied with gist changes. In the present study we aimed to examine how the alteration of gist, as well as the consistency of the changed objects, modulated change detection. In Experiment 1, we manipulated the semantic content by either keeping or changing the consistency of the scene. Results showed that the changes of consistent and inconsistent scenes were equally detected. More importantly, the changes were more accurately detected when scene consistency changed than when the consistency remained unchanged, regardless of the consistency of the memory scenes. A phase-scrambled version of stimuli was adopted in Experiment 2 to decouple the possible confounding effect of low-level factors. The results of Experiment 2 demonstrated that the effect found in Experiment 1 was indeed due to the change of high-level semantic consistency rather than the change of low-level physical features. Together, the study suggests that the change of consistency plays an important role in scene short-term memory, which might be attributed to the sensitivity to the change of semantic content.

Moderate irrigation intervals facilitate establishment of two desert shrubs in the Taklimakan Desert Highway Shelterbelt in China.

BACKGROUND: Water influences various physiological and ecological processes of plants in different ecosystems, especially in desert ecosystems. The purpose of this study is to investigate the response of physiological and morphological acclimation of two shrubs Haloxylon ammodendron and Calligonum mongolicunl to variations in irrigation intervals. METHODOLOGY/PRINCIPAL FINDINGS: The irrigation frequency was set as 1-, 2-, 4-, 8- and 12-week intervals respectively from March to October during 2012-2014 to investigate the response of physiological and morphological acclimation of two desert shrubs Haloxylon ammodendron and Calligonum mongolicunl to variations in the irrigation system. The irrigation interval significantly affected the individual-scale carbon acquisition and biomass allocation pattern of both species. Under good water conditions (1- and 2-week intervals), carbon assimilation was significantly higher than other treatments; while, under water shortage conditions (8- and 12-week intervals), there was much defoliation; and under moderate irrigation intervals (4 weeks), the assimilative organs grew gently with almost no defoliation occurring. CONCLUSION/SIGNIFICANCE: Both studied species maintained similar ecophysiologically adaptive strategies, while C. mongolicunl was more sensitive to drought stress because of its shallow root system and preferential belowground allocation of resources. A moderate irrigation interval of 4 weeks was a suitable pattern for both plants since it not only saved water but also met the water demands of the plants.

An updated age for the Xujiayao hominin from the Nihewan Basin, North China: Implications for Middle Pleistocene human evolution in East Asia.

The Xujiayao site in the Nihewan Basin (North China) is one of the most important Paleolithic sites in East Asia. Twenty Homo fossils, which were previously assigned to an archaic Homo sapiens group, have been excavated along with more than 30,000 lithic artifacts and ∼5000 mammalian fossil specimens. Dating of the Xujiayao hominin has been pursued since its excavation in the 1970s, but its age has remained controversial because of limitations of the dating techniques that have been applied to available materials. Here, we report new ages for the Xujiayao hominin based on combined electron spin resonance (ESR) dating of quartz in the sediments and high-resolution magnetostratigraphy of the fluvio-lacustrine sequence. The magnetostratigraphy suggests that the upper Matuyama and Brunhes polarity chrons are recorded at Xujiayao. The ESR dating results indicate a pooled average age of 260-370 ka for the Homo-bearing layer, which is consistent with its position within the middle Brunhes normal polarity chron indicated by magnetostratigraphy. This age estimate makes the Xujiayao hominin among the oldest mid-Pleistocene hominins with derived Neanderthal traits in East Asia. This age is consistent with the time when early Denisovans, a sister group of Neanderthals, appeared and colonized eastern Eurasia. Our updated age and the Neanderthal-like traits of the Xujiayao Homo fossils, particularly the Denisovan-like molar teeth, make it possible that the Xujiayao hominin could represent an early Denisovan.