A mixed blessing of influent leachate microbes in downstream biotreatment systems of a full-scale landfill leachate treatment plant.

In landfill leachate treatment plants (LLTPs), the microbiome plays a pivotal role in the decomposition of organic compounds, reduction in nutrient levels, and elimination of toxins. However, the effects of microbes in landfill leachate influents on downstream treatment systems remain poorly understood. To address this knowledge gap, we collected 23 metagenomic and 12 metatranscriptomic samples from landfill leachate and activated sludge from various treatment units in a full-scale LLTP. We successfully recovered 1,152 non-redundant metagenome-assembled genomes (MAGs), encompassing a wide taxonomic range, including 48 phyla, 95 classes, 166 orders, 247 families, 238 genera, and 1,152 species. More diverse microbes were observed in the influent leachate than in the downstream biotreatment systems, among which, an unprecedented ∼30 % of microbes with transcriptional expression migrated from the influent to the biological treatment units. Network analysis revealed that 399 shared MAGs across the four units exhibited high node centrality and degree, thus supporting enhanced interactions and increased stability of microbial communities. Functional reconstruction and genome characterization of MAGs indicated that these shared MAGs possessed greater capabilities for carbon, nitrogen, sulfur, and arsenic metabolism compared to non-shared MAGs. We further identified a novel species of Zixibacteria in the leachate influent with discrete lineages from those in other environments that accounted for up to 17 % of the abundance of the shared microbial community and exhibited notable metabolic versatility. Meanwhile, we presented groundbreaking evidence of the involvement of Zixibacteria-encoded genes in the production of harmful gas emissions, such as N2O and H2S, at the transcriptional level, thus suggesting that influent microbes may pose safety risks to downstream treatment systems. In summary, this study revealed the complex impact of the influent microbiome on LLTP and emphasizes the need to consider these microbial characteristics when designing treatment technologies and strategies for landfill leachate management.

Occurrence, mass loading, and post-control temporal trend of legacy perfluoroalkyl substances (PFASs) in the middle and lower Yangtze River.

Present study focused on per- and polyfluoroalkyl substances (PFASs) occurrence in dry and wet seasons in the middle and lower Yangtze River (YZR) and changing temporal trends after years of control. Results revealed that perfluorooctanoic acid (PFOA) was 75 % of total PFAS concentrations (∑11PFASs). ∑11PFASs were ranged 0.20-28.49 ng/L and 1.17-112.84 µg/kg in water and sediment. The logKoc of perfluoroalkyl carboxylic acids was positive with the carbon chain length (p < 0.05, r2 = 0.78). A meta-analysis of results from 16 peer-reviewed publications about PFASs in the YZR showed that fluorochemical industries strongly influenced the high PFAS levels in the detected scenes. PFOA was still the primary pollutant. Individual PFAS in the lower reach was higher than those in the middle reach. The mass loading of PFASs imported into the sea was 10.80 t/y. This study will help develop effective approaches for controlling emerging pollutants in the YZR.

Planktonic/benthic Bathyarchaeota as a "gatekeeper" enhance archaeal nonrandom co-existence and deterministic assembling in the Yangtze River.

Archaea, the third proposed domain of life, mediate carbon and nutrient cycling in global natural habitats. Compared with bacteria, our knowledge about archaeal ecological modes in large freshwater environments subject to varying natural and human factors is limited. By metabarcoding analysis of 303 samples, we provided the first integrate biogeography about archaeal compositions, co-existence networks, and assembling processes within a 6000 km continuum of the Yangtze River. Our study revealed that, among the major phyla, water samples owned a higher proportion of Thaumarchaeota (62.8%), while sediments had higher proportions of Euryarchaeota (33.4%) and Bathyarchaeota (18.8%). A decline of polarization in phylum abundance profile was observed from plateau/mountain/hill to basin/plain areas, which was attributed to the increase of nutrients and metals. Planktonic and benthic Bathyarchaeota tended to co-occur with both major (e.g., methanogens or Thermoplasmata) and minor (e.g., Asgard or DPANN) taxa in the non-random networks, harboring the highest richness and abundances of keystone species and contributing the most positively to edge number, node degree, and nearest neighbor degree. Furthermore, we noted significantly positive contributions of Bathyarchaeota abundance and network complexity to the dominance of deterministic process in archaeal assembly (water: 65.3%; sediments: 92.6%), since higher carbon metabolic versatility of Bathyarchaeota would benefit archaeal symbiotic relations. Stronger deterministic assembling was identified at the lower-reach plain, and higher concentrations of ammonium and aluminum separately functioning as nutrition and agglomerator were the main environmental drivers. We lastly found that the Three Gorges Dam caused a simultaneous drop of benthic Bathyarchaeota abundance, network co-existence, and deterministic effects immediately downstream due to riverbed erosion as a local interference. These findings highlight that Bathyarchaeota are a "gatekeeper" to promote fluvial archaeal diversity, stability, and predictability under varying macroscopic and microscopic factors, expanding our knowledge about microbial ecology in freshwater biogeochemical cycling globally.

Metagenomic analysis unveils the underexplored roles of prokaryotic viruses in a full-scale landfill leachate treatment plant.

Enormous viral populations have been identified in activated sludge systems, but their ecological and biochemical roles in landfill leachate treatment plants remain poorly understood. To address this knowledge gap, we conducted an in-depth analysis using 36 metagenomic datasets that we collected and sequenced during a half-year time-series sampling campaign at six sites in a full-scale landfill leachate treatment plant (LLTP), elucidating viral distribution, virus‒host dynamics, virus-encoded auxiliary metabolic genes (AMGs), and viral contributions to the spread of virulence and antibiotic resistance genes. Our findings demonstrated that viral and prokaryotic communities differed widely among different treatment units, with stability over time. LLTP viruses were linked to various prokaryotic hosts, spanning 35 bacterial phyla and one archaeal phylum, which included the core microbes involved in biological treatments, as well as some of the less well-characterized microbial dark matter phyla. By encoding 2364 auxiliary metabolic genes (AMGs), viruses harbored the potential to regulate microbial nucleotide metabolism, facilitate the biodegradation of complex organic matter, and enhance flocculation and settling in biological treatment plants. The abundance distribution of AMGs varied considerably across treatment units and showed a lifestyle-dependent pattern with temperate virus-associated AMGs exhibiting a higher average abundance in downstream biological treatment units and effluent water. Meanwhile, temperate viruses tended to carry a higher load of virulence factor genes (VFGs), antibiotic resistance genes (ARGs), and biotic and metal resistance genes (BMRGs), and engaged in more frequent gene exchanges with prokaryotes than lytic viruses, thus acting as a pivotal contributor to the dissemination of pathogenicity and resistance genes in downstream LLTP units. This study provided a comprehensive profile of viral and prokaryotic communities in the LLTP and unveiled the varying roles of different-lifestyle viruses in biochemical processes and water quality safety.

Ecological differentiation and assembly processes of abundant and rare bacterial subcommunities in karst groundwater.

The ecological health of karst groundwater has been of global concern due to increasing anthropogenic activities. Bacteria comprising a few abundant taxa (AT) and plentiful rare taxa (RT) play essential roles in maintaining ecosystem stability, yet limited information is known about their ecological differentiation and assembly processes in karst groundwater. Based on a metabarcoding analysis of 64 groundwater samples from typical karst regions in southwest China, we revealed the environmental drivers, ecological roles, and assembly mechanisms of abundant and rare bacterial communities. We found a relatively high abundance of potential functional groups associated with parasites and pathogens in karst groundwater, which might be linked to the frequent regional anthropogenic activities. Our study confirmed that AT was dominated by Proteobacteria and Campilobacterota, while Patescibacteria and Chloroflexi flourished more in the RT subcommunity. The node-level topological features of the co-occurrence network indicated that AT might share similar niches and play more important roles in maintaining bacterial community stability. RT in karst groundwater was less environmentally constrained and showed a wider environmental threshold response to various environmental factors than AT. Deterministic processes, especially homogeneous selection, tended to be more important in the community assembly of AT, whereas the community assembly of RT was mainly controlled by stochastic processes. This study expanded our knowledge of the karst groundwater microbiome and was of great significance to the assessment of ecological stability and drinking water safety in karst regions.

Bioaccumulation of pharmaceuticals and personal care products (PPCPs) in freshwater pearl mussels Hyriopsis cumingii in Poyang Lake.

Thirty-five PPCPs were measured in representative freshwater pearl mussels (Hyriopsis cumingii) in Poyang Lake, the largest lake of China, as well as their responses to sedimentary PPCPs. We observed 32 PPCPs in soft tissues of mussels at a total concentration of 2721.5 ± 929.3 ng·g-1 dry weight (dw), much higher than those in sediments (21 PPCPs, 273.2 ± 89.4 ng·g-1 dw). Anti-inflammatories were the primary contaminants detected in both sediments and mussels. PPCP concentrations in mussels exhibited significant organ-specific characteristics, and gonads were identified as a hotspot for these contaminants. Correlation analysis showed that gonads were more likely to assimilate triclosan from sediments. Biochemical analysis revealed a higher physiological sensitivity of glutathione synthesis in gonads to sedimentary PPCPs, suggesting the long-term oxidative damage. Our findings highlight the concern on the potential effects of sedimentary PPCPs to propagation of mussels, and emphasize the necessity to formulate strategies for sedimentary PPCPs control targeting a healthy lake.

Occurrence, distribution and risk assessment of polycyclic aromatic hydrocarbons in soils around main water source areas of Beijing, China.

Polycyclic aromatic hydrocarbons (PAHs) in urban environments have been globally concerned due to their significant health impacts on residents. However, little is known about potential risks of PAHs from centralized water source areas. In the present study, 326 soils samples from the main water source areas of Beijing were collected and the occurrence, source appointment, and risks of PAHs were systematically investigated based on the monitoring results from high-performance liquid chromatography (HPLC). The total PAHs (∑16 PAHs) concentrations ranged from 5.70 to 1512 ng/g with median value of 44.2 ng/g, in which 4-ring and 5-ring groups were the major components. PAHs concentrations in the cultivated land were significantly higher than other areas, which could reflect significant impact of soil organic matter and total nitrogen contents on the spatial variations of PAHs. Further source identifications through positive matrix factorization model (PMF) revealed that biomass (22.5%), coal (21.4%), gasoline (17.6%) and diesel (16.4%) combustion were dominant sources of soil PAHs in the study area. Moreover, the risk assessment indicated that total ecological and health risk of PAHs were negligible, but individual PAH, including pyrene and benzo(b)fluoranthene, should be concerned due to their potential risks in several monitored stations located in the secondary protection area of four reservoirs. Our study provided new insights into environmental risks of soils in main water source areas from PAHs and could be helpful for organic micropollutant controlling and drinking water safety in rapidly urbanizing cities.

Structure, stability, and potential function of groundwater microbial community responses to permafrost degradation on varying permafrost of the Qinghai-Tibet Plateau.

The ongoing permafrost degradation under climate warming has modified aboveground biogeochemical processes mediated by microbes, yet groundwater microbial structure and function as well as their response to permafrost degradation remain poorly understood. We separately collect 20 and 22 sub-permafrost groundwater samples from Qilian Mountain (alpine and seasonal permafrost) and Southern Tibet Valley (plateau isolated permafrost) on the Qinghai-Tibet Plateau (QTP) to investigate the effects of permafrost groundwater characteristics on the diversity, structure, stability, and potential function of bacterial and fungal communities. Regional discrepancy of groundwater microbes between two permafrost regions reveals that permafrost degradation might reshape microbial community structure, increase community stability and potential functions relevant to carbon metabolism. Bacterial community assembly in permafrost groundwater is governed by deterministic processes, whereas fungal communities are mainly controlled by stochastic processes, suggesting that bacterial biomarkers might provide the better 'early warning signals' to permafrost degradation in deeper layers. Our study highlights the importance of groundwater microbes in ecological stability and carbon emission on the QTP.

Early neurological deterioration in patients with acute ischemic stroke: a prospective multicenter cohort study.

Background: There is still no precise knowledge of the causes of progression in patients with acute ischemic stroke (AIS), and we are unable to predict patients at risk. Objective: To explore the frequency, predictive factors, and the prognosis of early neurological deterioration (END) in patients with AIS. Methods: In this prospective multicenter observational study, we assessed patients with AIS admitted to 18 hospitals in Henan, China. We defined END as an increase of ⩾2 points in total National Institutes of Health Stroke Scale (NIHSS) score or ⩾1 point in the motor items of the NIHSS within 7 days after admission. Risk factors were analyzed using multivariate logistic regression models. Prognosis was evaluated using the modified Rankin Scale (mRS), with poor prognosis defined as mRS 3-6. Results: A total of 9114 patients with AIS within 24 h of symptom onset were enrolled in the study. END occurred in 1286 (14.1%) patients. The highest incidence (62.5%) of END occurred within 24 h after admission. After adjusting potential confounders, age, body mass index, waist-hip ratio, systolic blood pressure, baseline NIHSS, disabled at baseline, history of atrial fibrillation, diabetes mellitus, intracranial arterial stenosis, infarct location in the lenticulostriate artery area and cerebral watershed, neutrophils, lymphocytes, uric acid, and triglycerides were identified as independent predictors for END. END was significantly associated with poor prognosis at 90 days, and the adjusted OR was 1.74 (95% CI: 1.53-1.97). Conclusion: One in seven hospitalized patients with AIS may experience END within 24 h of onset. The highest incidence of END occurred within 24 h of admission and decreased steeply with time. Easily identifiable risk factors predict END and could help understand the causal mechanisms and thereby prevent END.

Antibiotic profiles and their relationships with multitrophic aquatic communities in an urban river.

Antibiotics have garnered worldwide attention due to their omnipresence and detrimental effects on aquatic organisms, yet their potential relationships with multitrophic aquatic communities in natural rivers remain largely unknown. Here, we examined 107 antibiotics in water and sediment from an urban river in Chengdu, Sichuan province (China). The bacterial, algal, macroinvertebrates, and fish communities were synchronously measured based on the environmental DNA (eDNA) metabarcoding approach, and their relationships with antibiotics were further investigated. The results showed that the total antibiotic concentrations ranged from 1.12 to 377 ng/L and from 7.95 to 145 ng/g in water and sediment, respectively. Significant seasonal variations in the concentrations and compositions of antibiotics in water were observed. eDNA metabarcoding revealed great compositional variations of bacterial, algal, macroinvertebrates, and fish communities along the river, and antibiotics had significant negative relationships with the community diversities of aquatic organisms (p < 0.05) except for fish. Meanwhile, significant negative correlations were observed between antibiotic concentrations and the relative abundances of essential metabolism pathways of bacteria, e.g., energy metabolism (p < 0.05), carbohydrate metabolism (p < 0.05), and lipid metabolism (p < 0.01). Moreover, antibiotics demonstrated greater effects on the function of bacterial community compared with environmental variables. The findings highlight the significance of eDNA metabarcoding approach in revealing the relationships between aquatic communities and antibiotics, and call for further studies on the effects of antibiotics on multitrophic aquatic communities in natural waters.

Pistachio genomes provide insights into nut tree domestication and ZW sex chromosome evolution.

Pistachio is a nut crop domesticated in the Fertile Crescent and a dioecious species with ZW sex chromosomes. We sequenced the genomes of Pistacia vera cultivar (cv.) Siirt, the female parent, and P. vera cv. Bagyolu, the male parent. Two chromosome-level reference genomes of pistachio were generated, and Z and W chromosomes were assembled. The ZW chromosomes originated from an autosome following the first inversion, which occurred approximately 8.18 Mya. Three inversion events in the W chromosome led to the formation of a 12.7-Mb (22.8% of the W chromosome) non-recombining region. These W-specific sequences contain several genes of interest that may have played a pivotal role in sex determination and contributed to the initiation and evolution of a ZW sex chromosome system in pistachio. The W-specific genes, including defA, defA-like, DYT1, two PTEN1, and two tandem duplications of six VPS13A paralogs, are strong candidates for sex determination or differentiation. Demographic history analysis of resequenced genomes suggest that cultivated pistachio underwent severe domestication bottlenecks approximately 7640 years ago, dating the domestication event close to the archeological record of pistachio domestication in Iran. We identified 390, 211, and 290 potential selective sweeps in 3 cultivar subgroups that underlie agronomic traits such as nut development and quality, grafting success, flowering time shift, and drought tolerance. These findings have improved our understanding of the genomic basis of sex determination/differentiation and horticulturally important traits and will accelerate the improvement of pistachio cultivars and rootstocks.

Environmental DNA metabarcoding reveals the impacts of anthropogenic pollution on multitrophic aquatic communities across an urban river of western China.

Anthropogenic activities are intensively affecting the structure and function of biological communities in river ecosystems. The effects of anthropogenic pollution on single-trophic community have been widely explored, but their effects on the structures and co-occurrence patterns of multitrophic communities remain largely unknown. In this study, we collected 13 water samples from the Neijiang River in Chengdu City of China, and identified totally 2352 bacterial, 207 algal, 204 macroinvertebrate, and 33 fish species based on the eDNA metabarcoding to systematically investigate the responses of multitrophic communities to environmental stressors. We observed significant variations in bacterial, algal, and macroinvertebrate community structures (except fish) with the pollution levels in the river. Network analyses indicated a more intensive interspecific co-occurrence pattern at high pollution level. Although taxonomic diversity of the multitrophic communities varied insignificantly, phylogenetic diversities of fish and algae showed significantly positive and negative associations with the pollution levels, respectively. We demonstrated the primary role of environmental filtering in driving the structures of bacteria, algae, and macroinvertebrates, while the fish was more controlled by dispersal limitation. Nitrogen was identified as the most important factor impacting the multitrophic community, where bacterial composition was mostly associated with NO3--N, algal spatial differentiation with TN, and macroinvertebrate and fish with NH4+-N. Further partial least-squares path model confirmed more important effect of environmental variables on the relative abundance of bacteria and algae, while macroinvertebrate and fish communities were directly driven by the algae-mediated pathway in the food web. Our study highlighted the necessity of integrated consideration of multitrophic biodiversity for riverine pollution management, and emphasized the importance of controlling nitrogen inputs targeting a healthy ecosystem.

Comammox biogeography subject to anthropogenic interferences along a high-altitude river.

The recent discovery of comammox Nitrospira performing complete ammonia oxidation to nitrate has overturned the long-held dogma of two-step nitrification on Earth, yet little is known about the effect of urbanization interference on their distribution. Using gene-centric metagenomics, we provided the first blueprints about comammox community, biogeography, and environmental drivers along a high-elevation (> 2000 m) river flowing through the largest city on the vulnerable Qinghai-Tibetan Plateau. Our study confirmed a wide presence and diversity of yet-uncultured comammox clade B across wet and dry seasons, with average 3.0 and 2.0 times as abundant as clade-A amoA genes in water and sediments, respectively. Species identified from freshwater and drinking water treatment plants dominated the comammox guilds (58∼100%), suggesting this plateau river shared a similar comammox assemblage with the above habitat types. Compared with the urban area harboring more abundant canonical Nitrospira identified in wastewater (average 24%), the upstream suburban reach had a smaller human population but larger proportions of comammox in ammonia-oxidizing prokaryotes (24∼72% of abundances) and Nitrospira sublineages I/II. Higher contents of nitrate and nitrite in water, and antibiotics in water and sediments, may restrain comammox niches in nitrifiers over the urban area. Further random forest analysis revealed that lincosamides and quinolones were the most important antibiotic predictors for the niche differentiations between comammox and canonical nitrifiers in water, while macrolides for those in sediments. Finally, by incubation experiments, we demonstrated higher activity contributions of benthic comammox in the suburban area (36.2∼92.8% of potential ammonia-oxidation rates) than in the urban reach, and that the contribution variation had significant negative relations with macrolides and their major components. Overall, this study highlighted that anthropogenic activities hampered the advantage of riverine complete nitrifiers over the canonical two-step ones.

Bioaccumulation of 35 metal(loid)s in organs of a freshwater mussel (Hyriopsis cumingii) and environmental implications in Poyang Lake, China.

Benthic bioaccumulation of hazardous materials has been a great challenge to the health of lake ecosystems. As representative benthic macroinvertebrates, freshwater mussels and their accumulation characteristics have been regarded as effective indicators for assessing potential risks induced by sedimentary metal(loid)s in lakes. Here we profile organ-specific accumulation of 35 metal(loid)s in a freshwater mussel (Hyriopsis cumingii) and their correlations to metal speciation in sediments of Poyang Lake, the largest lake of China. Significant organ-specific characteristics of metal accumulation were found in gills, though higher thallium (Tl) and selenium (Se) were found in the hepatopancreas, and greater arsenic (As) mostly accumulated in gonads. Pearson correlation analysis revealed that the bioaccumulation of silver (Ag), cobalt (Co), and rare earth elements (ΣREE) in gills and As in gonads were closely associated with those in bioavailable fraction of sediments. Based on the biochemical analysis in the major organs, gills exhibited the highest enzymatic activity compared with hepatopancreas and gonads. Sedimentary metals, particularly for available Ag, Co, and ΣREE, play key roles in causing lipid peroxidation in gills and significantly promote the activities of superoxide dismutase (SOD)/glutathione reductase (GR), while many metals (e.g., cadmium, manganese, Se) inhibit the glutathione (GSH) content in gonads and hepatopancreas. Our study indicates a high physiological sensitivity of mussels to these target metals, which highlights the significance of organ-specific accumulation of metal(loid)s in understanding the potential ecological risks of sedimentary metal(loid)s in lake ecosystems.

Impacts of engineered nanoparticles and antibiotics on denitrification: Element cycling functional genes and antibiotic resistance genes.

The wide presence of antibiotics and minerals warrants their combined effects on the denitrification in natural aquatic environment. Herein, we investigated the effects of two antibiotics, sulfamethazine (SMZ) and chlortetracycline (CTC), on the reduction of NO3--N and accumulation of NO2--N in the absence and presence of engineered nanoparticles (NPs) (Al2O3, SiO2, and geothite) using 16 S rRNA sequencing and high-throughput quantitative PCR. The results showed that the addition of antibiotics inhibited the reduction of NO3--N by changing the bacterial community structure and reducing the abundance of denitrification genes, while engineered NPs promoted the denitrification by increasing the abundance of denitrification genes. In the binary systems, engineered NPs alleviated the inhibitory effect of antibiotics through enriching the denitrification genes and adsorbing antibiotics. Antibiotics and its combination with engineered NPs changed the composition of functional genes related to C, N, P, S metabolisms (p < 0.01). The addition of antibiotics and/or engineered NPs altered the bacterial community structure, which is dominated by the genera of Enterobacter (40.7-90.5%), Bacillus (4.9-58.5%), and Pseudomonas (0.21-12.7%). The significant relationship between denitrification, carbon metabolism genes, and antibiotic resistance genes revealed that the heterotrophic denitrifying bacteria may host the antibiotic resistance genes and denitrification genes simultaneously. The findings underscore the significance of engineered NPs in the toxicity assessment of pollutants, and provide a more realistic insight into the toxicity of antibiotics in the natural aquatic environment.

Per- and polyfluoroalkyl substances (PFASs) in groundwater from a contaminated site in the North China Plain: Occurrence, source apportionment, and health risk assessment.

Per-and polyfluoroalkyl substances (PFASs) are manmade chemicals that have wide industrial and commercial application. However, little research has been carried out on PFASs pollution in groundwater from a previously contaminated site. Here, we investigated 43 PFASs in a monitoring campaign from two different aquifers in the North China Plain. Our results revealed that total PFASs concentrations (∑43PFASs) ranged from 0.22 to 3,776.76 ng/L, with no spatial or compositional differences. Moreover, perfluorooctanoic acid (PFOA) and perfluoroheptane sulfonate (PFHpS) were the dominant pollutants with mean concentrations of 177.33 ng/L and 51 ng/L, respectively. ∑43PFAS decreased with well depth due to the adsorption of PFASs to the aquifer materials. Water temperature, total organic carbon, dissolved oxygen, and total phosphorus concentrations were correlated to the PFAS concentrations. Principal component analysis indicated that the main sources of PFASs in groundwater were untreated industrial discharge, untreated domestic wastewater, food packaging, aqueous film forming foams and metal plating, and surface runoff, which overlapped with the industries that previously existed in a nearby city. Human health risks from drinking contaminated groundwater were low to the local residents, with children aged 1-2 years being the most sensitive group. One specific site with a high PFOA concentration was of concern, as it was several orders higher than the 70 ng/L recommended by US Environmental Protection Agency health advisory. This study provided baseline data for PFASs in a previously-contaminated site, which will help in the development of effective strategies for controlling PFASs pollution in the North China Plain.

Pharmaceuticals and personal care products (PPCPs) in water, sediment and freshwater mollusks of the Dongting Lake downstream the Three Gorges Dam.

Pharmaceuticals and personal care products (PPCPs) are a group of emerging anthropogenic pollutants. Here we investigated the occurrence and concentrations of 35 typical PPCPs in water, sediment, and freshwater mollusks (Hyriopsis cumingii, Unio douglasiae, Sinanodonta woodiana, Lamprotula leai and Corbicula fluminea) of the Dongting Lake downstream of the Three Gorges Dam. As results, 33 PPCPs were detected in water and sediment of the lake. Ketoprofen (not detected (ND)-292.8 ng/L, mean 91.1 ng/L) and roxithromycin (13.7-141.9 ng/L, mean 30.4 ng/L) were the primary PPCPs measured in lake water, while ibuprofen (ND-105.0 ng/g, mean 30.0 ng/g) and ketoprofen (ND-142.9 ng/g, mean 27.6 ng/g) were dominant in the sediment. Distinct seasonal difference in PPCP compositions was observed in both water and sediment of the Dongting Lake, potentially associated with the water-level fluctuations driven by the Three Gorges Dam operations. Ketoprofen and ibuprofen were also frequently detected in the soft tissues of freshwater mollusks, with concentrations of 42.5-1206.6 and 44.9-992.7 ng/g, respectively. Significant species-specific accumulation characteristics of PPCPs in mollusks were observed, with the highest total contents being reported for Corbicula fluminea (3.18 ± 1.13 µg/g). Moreover, gonads of mollusks were identified as the target organ to accumulate these compounds. Correlation analysis further revealed the strong associations of PPCP concentrations in mollusks with those in water and sediment, suggesting the importance of controlling dissolved and sedimentary bioavailability of PPCPs for ecological risk management in this freshwater lake ecosystems.

Unveil the role of dissolved and sedimentary metal(loid)s on bacterial communities and metal resistance genes (MRGs) in an urban river of the Qinghai-Tibet Plateau.

Though metal resistance genes (MRGs) are of global concern in aquatic ecosystems, the underlying factors responsible for MRGs dissemination, especially in urban rivers on the vulnerable Qinghai-Tibet Plateau, are rarely known. Here, we collected 64 samples including water and sediments during the wet and dry seasons and effluents from six wastewater treatment plants (WWTPs) during the dry season and measured 50 metal(loid)s, 60 bacterial phyla, and 259 MRGs. We observed the distinct difference of metal(loid)s, bacterial communities, and MRGs between water and sediments and the great seasonal changes in metal(loid)s and bacterial communities instead of MRGs. Thirty-one metal(loid)s were detectable in the water, with relatively low concentrations and no significant effects on the planktonic bacterial communities and MRGs. Interestingly, the WWTPs effluent partially promoted the prevalence of dissolved metal(loid)s, bacterial communities, and MRGs along the river. In the sediments, the average concentrations of 17 metal(loid)s exceeded their corresponding background levels in this region and strongly influenced the bacterial communities and the MRGs. Sedimentary Hg and Cd, mainly sourced from the intensive animal husbandry, were the major pollutants causing ecological risks and largely shaped their corresponding resistomes. Moreover, we found that bacterial communities predominantly determined the variation of MRGs in both water and sediments. Metagenome-assembled genomes further reveals the widespread co-occurrence of MRGs and antibiotic resistance genes (ARGs) in MRG hosts. Our study highlighted the concern of effluents discharged from WWTPs and emphasized the importance of controlling the anthropogenic inputs of sedimentary metal(loid)s in the plateau river ecosystems.

Sediments alleviate the inhibition effects of antibiotics on denitrification: Functional gene, microbial community, and antibiotic resistance gene analysis.

Both antibiotics and sediments can affect the denitrification in aquatic systems. However, little is known how antibiotics influence the denitrification in the presence of sediments. Here, the effects of antibiotics (sulfamethoxazole, tetracycline and ofloxacin) on denitrification in the absence and presence of sediments were investigated. The influencing mechanisms were revealed by quantifying the denitrification functional genes (DNGs), 16S-seq of bacteria, and antibiotic resistance genes (ARGs). The results showed that the presence of antibiotics inhibited NO3-N reduction by decreasing the abundances of narG, nirK, nosZ, total DNGs, and denitrifying bacteria. However, the inhibition effect was alleviated by sediments, which promoted the growth of bacteria and decreased the selective pressure of antibiotics as the vector of bacteria and antibiotics, thus increasing the abundances of denitrifying bacteria and all the DNGs. Partial least-squares path model disclosed that antibiotics had negative effects on bacteria, ARGs and DNGs, while sediments had negative effects on ARGs but positive effects on bacteria and DNGs. The network analysis further revealed the close relation of the genera Bacillus, Acinetobacter, and Enterobacter with the ARGs and DNGs. The findings are helpful to understand the denitrification in antibiotic-polluted natural waters.

Neural Stem Cells Direct Axon Guidance via Their Radial Fiber Scaffold.

Neural stem cells directly or indirectly generate all neurons and macroglial cells and guide migrating neurons by using a palisade-like scaffold made of their radial fibers. Here, we describe an unexpected role for the radial fiber scaffold in directing corticospinal and other axons at the junction between the striatum and globus pallidus. The maintenance of this scaffold, and consequently axon pathfinding, is dependent on the expression of an atypical RHO-GTPase, RND3/RHOE, together with its binding partner ARHGAP35/P190A, a RHO GTPase-activating protein, in the radial glia-like neural stem cells within the ventricular zone of the medial ganglionic eminence. This role is independent of RND3 and ARHGAP35 expression in corticospinal neurons, where they regulate dendritic spine formation, axon elongation, and pontine midline crossing in a FEZF2-dependent manner. The prevalence of neural stem cell scaffolds and their expression of RND3 and ARHGAP35 suggests that these observations might be broadly relevant for axon guidance and neural circuit formation.