Distribution characteristics and microbial synergistic degradation potential of polyethylene and polypropylene in freshwater estuarine sediments

The microbial degradation of polyethylene (PE) and polypropylene (PP) resins in rivers and lakes has emerged as a crucial issue in the management of microplastics. This study revealed that as the flow rate decreased longitudinally, ammonia nitrogen (NH4+-N), heavy fraction of organic carbon (HFOC), and small-size microplastics (< 1 mm) gradually accumulated in the deep and downstream estuarine sediments. Based on their surface morphology and carbonyl index, these sediments were identified as the potential hot zone for PE/PP degradation. Within the identified hot zone, concentrations of PE/PP-degrading genes, enzymes, and bacteria were significantly elevated compared to other zones, exhibiting strong intercorrelations. Analysis of niche differences revealed that the accumulation of NH4+-N and HFOC in the hot zone facilitated the synergistic coexistence of key bacteria responsible for PE/PP degradation within biofilms. The findings of this study offer a novel insight and comprehensive understanding of the distribution characteristics and synergistic degradation potential of PE/PP in natural freshwater environments.

Interaction patterns and keystone taxa of bacterial and eukaryotic communities during sulfamethoxazole mineralization in lake sediment

Sulfamethoxazole (SMX) is a common antibiotic pollutant in aquatic environments, which is highly persistent under various conditions and significantly contributes to the spread of antibiotic resistance. Biodegradation is the major pathway to eliminate antibiotics in the natural environment. The roles of bacteria and eukaryotes in the biodegradation of antibiotics have received considerable attention; however, their successions and co-occurrence patterns during the biodegradation of antibiotics remain unexplored. In this study, 13C-labled SMX was amended to sediment samples from Zhushan Bay (ZS), West Shore (WS), and Gonghu Bay (GH) in Taihu Lake to explore the interplay of bacterial and eukaryotic communities during a 30-day incubation period. The cumulative SMX mineralization on day 30 ranged from 5.2 % to 19.3 %, which was the highest in WS and the lowest in GH. The bacterial community showed larger within-group interactions than between-group interactions, and the positive interactions decreased during incubation. However, the eukaryotic community displayed larger between-group interactions than within-group interactions, and the positive interactions increased during incubation. The proportion of negative interactions between bacteria and eukaryotes increased during incubation. Fifty genera (including 46 bacterial and 4 eukaryotic genera) were identified as the keystone taxa due to their dominance in the co-occurrence network and tolerance to SMX. The cumulative relative abundance of these keystone taxa significantly increased during incubation and was consistent with the SMX mineralization rate. These taxa closely cooperated and played vital roles in co-occurrence networks and microbial community interactions, signifying their crucial role in SMX mineralization. These findings broadened our understanding of the complex interactions of microorganisms under SMX exposure and their potential functions during SMX mineralization, providing valuable insights for in situ bioremediation.

CT venography combined with ultrasound-guided minimally invasive treatment for recurrent varicose veins: a pilot paired-design clinical trial

AIM

To compare 1-year outcomes of computed tomography venography (CTV) combined with ultrasound-guided minimally invasive treatment with ascending phlebography and ultrasound-guided treatment for recurrent varicose veins.

MATERIALS AND METHODS

Consecutive patients with unilateral recurrent varicose veins were matched by gender, age, C classification, and degree of obesity, and randomised in a 1:1 ratio to receive either CTV (CTV group) or ascending phlebography (control group) combined with ultrasound-guided minimally invasive treatment. Patients were followed up by clinical and ultrasound examination. Follow-up was scheduled at 1 week, and 3, 6, and 12 months. The primary outcome measure was the Venous Clinical Severity Score (VCSS) at 12 months. Measures of secondary outcome included Chronic Insufficiency Venous International Questionnaire-20 (CIVIQ-20) score, recurrence of varicose vein or ulcer during 12 months, ulcer healing time, detection and location of treated veins.

RESULTS

Eighty patients were enrolled. Median VCSS in the CTV group was lower than it in the control group (p=0.04) and the CIVIQ-20 score was higher than the control group (p=0.02). By 12 months, no symptomatically recurrent varicose veins or ulcers had occurred. The ulcer healing time in CTV group was shorter (p<0.01). A greater number of patients had treated veins detected using CTV than by ascending venography (p=0.01), especially among patients with recurrence reflux veins in the groin, perineum, and vulva (p<0.01).

CONCLUSION

CTV combined with ultrasound may be more helpful than ascending phlebography combined with ultrasound to improve treatment efficacy for recurrent varices. These results should be verified by an future study with more patients and long-term follow-up.

Clinical and radiographic outcomes of a combined surgery approach to treat peri-implantitis

Peri-implant infra-bony defects are difficult to treat, and data on the management of peri-implantitis are lacking. The aim of this study was to evaluate the effect of a combined surgical approach to manage peri-implantitis: implantoplasty with xenogeneic bone grafting and a concentrated growth factor membrane. Two independent examiners analysed the medical records and radiographs taken before surgery and at the last follow-up. Data were analysed at the implant level; some patient-level data (age, sex, smoking habit) were also considered. Linear regression analysis with generalized estimating equations (GEE) was used to explore the effect of variables of interest (including marginal bone level (MBL)) on implantitis treatment success and resolution rates. The effect of the prosthesis type on postoperative clinical and radiographic parameters was also explored by GEE, with adjustment for age, sex, tooth site, location, follow-up duration, and implant length (model IV including all). Thirty patients with 72 implants were investigated. The implant survival rate was 100% over a mean observation period of 3.3 years (range 2-11 years). The treatment success rate (bone loss <0.5 mm, no bleeding on probing (BOP), no suppuration, probing depth (PD) < 5 mm) was higher in females than males (50% vs 19.0%; P = 0.008). At the last postoperative follow-up, the MBL (1.51 ± 1.07 vs 4.01 ± 1.13 mm), PD (3.61 ± 0.84 vs 6.54 ± 1.01 mm), and BOP (23.38 ± 23.18% vs 79.17 ± 15.51%) were significantly reduced when compared to pre-surgery values (all P < 0.001). Furthermore, a significantly higher PD reduction (β = -1.10 mm, 95% confidence interval -1.97 to -0.23 mm, P = 0.014) was observed for implants with a single crown than a full-arch prosthesis (GEE model IV). Preliminary clinical and radiographic data indicate that implantoplasty in combination with surgery could be an effective treatment option for peri-implantitis.

Transition of organic matter from allochthonous to autochthonous alters benthic nutrient dynamics via microbial food webs

The impoundment of rivers by dams has significantly modified sedimentation patterns and trophic structures. As a result, the algal-derived organic matter (OM), as opposed to terrestrial-derived OM, plays an increasingly important role along the river-reservoir gradient. This study utilized water-sediment microcosms to explore the impacts of allochthonous and autochthonous OM deposition on benthic nutrient dynamics mediated by microbial food webs. Our results revealed that OM addition led to increased fluxes of NH4+ and CO2, with the highest flux induced by cyanobacteria OM, followed by diatom and allochthonous OM. N2 release flux was promoted by allochthonous and diatom OM deposition but inhibited by cyanobacteria OM deposition. The amendment of autochthonous OM increased the activity of dehydrogenase and urease, while allochthonous OM with a higher C/N ratio enhanced the catalytic abilities of polyphenol oxidase and β-glucosidase. Furthermore, OM deposition significantly reduced microbial community richness and diversity, except for eukaryotic richness, and induced pronounced changes in bacterial and eukaryotic community structures. Allochthonous OM deposition stimulated the utilization of bacteria and protozoan on native OM, resulting in a positive priming effect of 26.78 %. In contrast, diatom and cyanobacteria OM additions exerted negative priming effects of -44.53 % and -29.76 %, respectively. Bayesian stable isotope mixing models showed that diatom OM was primarily absorbed by protozoan and metazoan, while cyanobacteria OM was more easily decomposed by bacteria and transferred to higher trophic levels through microbial food webs. In addition, bacterial ammonification accounted for 74.5 % of NH4+ release in the allochthonous OM deposition treatment, whereas eukaryotic excretion contributed separately 83.3 % and 83.1 % to NH4+ release in the diatom and cyanobacteria OM addition treatments. These findings highlight the significance of accounting for the regulatory capacity of OM deposition when studying benthic metabolism within river-reservoir systems.

DNDMH-mediated direct nitration of aryl alkenes

N-nitro type reagents have been demonstrated as mild nitration tools in recent years. This work presents an exploration of direct nitration of aryl alkenes mediated by DNDMH, a novel N-nitro type reagent developed in our previous study. It exhibits herein a new property of DNDMH as an effective direct nitration reagent for aryl alkenes, through probably the delivery of nitro radicals with the aid of TEMPO and Cu(OAc)2.

Climate and local environment co-mediate the taxonomic and functional diversity of bacteria and archaea in the Qinghai-Tibet Plateau rivers

Understanding the environmental response patterns of riverine microbiota is essential for predicting the potential impact of future environmental change on river ecosystems. Vulnerable plateau ecosystems are particularly sensitive to climate and local environmental changes, however, the environmental response patterns of the taxonomic and functional diversity of riverine microbiota remain unclear. Here, we conducted a systematic investigation of the taxonomic and functional diversity of bacteria and archaea from riparian soils, sediments, and water across the elevation of 1800- 4800 m in the Qinghai-Tibet Plateau rivers. We found that within the elevation range of 1800 to 3800 m, riparian soils and sediments exhibited similarities and stabilities in microbial taxonomic and functional diversity, and water microbiomes were more sensitive with great fluctuations in microbial diversity. Beyond the elevation of 3800 m, microbial diversity declined across all riverine matrixes. Local environmental conditions can influence the sensitivity of microbiomes to climate change. The combination of critical climate and local environmental factors, including total nitrogen, total organic carbon, as well as climate variables associated with temperature and precipitation, provided better explanations for microbial diversity than single-factor analyses. Under the extremely adverse scenario of high greenhouse gas emission concentrations (SSP585), we anticipate that by the end of this century, the bacterial, archaeal, and microbial functional diversity across the river network of the Yangtze and Yellow source basin would potentially change by -16.9- 5.2 %, -16.1- 5.7 %, and -9.3- 6.4 %, respectively. Overall, climate and local environments jointly shaped the microbial diversity in plateau river ecosystems, and water microbiomes would provide early signs of environmental changes. Our study provides effective theoretical foundations for the conservation of river biodiversity and functional stability under environmental changes.

Influence of rapid vertical mixing on bacterial community assembly in stratified water columns

Water column mixing homogenizes thermal and chemical gradients which are known to define distribution of microbial communities and influence the prevailing biogeochemical processes. Little is however known about the effects of rapid water column mixing on the vertical distribution of microbial communities in stratified reservoirs. To address this knowledge gap, physicochemical properties and microbial community composition from 16 S rRNA amplicon sequencing were analyzed before and after mixing of vertically stratified water-column bioreactors. Our results showed that α-diversity of bacterial communities decreased from bottom to surface during periods of thermal stratification. After an experimental mixing event, bacterial community diversity experienced a significant decrease throughout the water column and network connectivity was disrupted, followed by slow recovery. Significant differences in composition were seen for both total (DNA) and active (RNA) bacterial communities when comparing surface and bottom layer during periods of stratification, and when comparing samples collected before mixing and after re-stratification. The dominant predicted community assembly processes for stratified conditions were deterministic while such processes were less important during recovery from episodic mixing. Water quality characteristics of stratified water were significantly correlated with bacterial community diversity and structure. Furthermore, structural equation modeling analyses showed that changes in sulfur may have the greatest direct effect on bacterial community composition. Our results imply that rapid vertical mixing caused by episodic weather extremes and hydrological operations may have a long-term effect on microbial communities and biogeochemical processes.

Hypoxia and salinity constrain the sediment microbiota-mediated N removal potential in an estuary: A multi-trophic interrelationship perspective

Reactive nitrogen (N) enrichment is a common environmental problem in estuarine ecosystems, while the microbial-mediated N removal process is complicated for other multi-environmental factors. Therefore, A systematic investigation is necessary to understand the multi-trophic microbiota-mediated N removal characteristics under various environmental factors in estuaries. Here, we studied how multiple factors affect the multi-trophic microbiota-mediated N removal potential (denitrification and anammox) and N2O emission along a river-estuary-bay continuum in southeastern China using the environmental DNA (eDNA) approach. Results suggested that hypoxia and salinity were the dominant environmental factors affecting multi-trophic microbiota-mediated N removal in the estuary. The synergistic effect of hypoxia and salinity contributed to the loss of taxonomic (MultiTaxa) and phylogenetic (MultiPhyl) diversity across multi-trophic microbiota and enhanced the interdependence among multi-trophic microbiota in the estuary. The N removal potential calculated as the activities of key N removal enzymes was also significantly constrained in the estuary (0.011), compared with the river (0.257) and bay (0.461). Structural equation modeling illustrated that metazoans were central to all sediment N removal potential regulatory pathways. The top-down forces (predation by metazoans) restrained the growth of heterotrophic bacteria, which may affect microbial N removal processes in the sediment. Furthermore, we found that the hypoxia and salinity exacerbated the N2O emission in the estuary. This study clarifies that hypoxia and salinity constrain estuarine multi-trophic microbiota-mediated N removal potential and highlights the important role of multi-trophic interactions in estuarine N removal, providing a new perspective on mitigating estuarine N accumulation.

Enantioselective Total Synthesis of (-)-Cephalotanin B

Cephalotaxus diterpenoids are attractive natural products with intriguing molecular frameworks and promising biological features. As a structurally unusual member, (-)-cephalotanin B possesses an extraordinarily congested heptacyclic skeleton, three lactone units, and nine consecutive stereocenters. Herein, we report an enantioselective total synthesis of (-)-cephalotanin B based on a divergent asymmetric Michael addition reaction, a novel Pauson-Khand/deacyloxylation process discovered in the development of a second-generation stereoselective Pauson-Khand reaction protocol, and an epoxide-opening/elimination/dual-lactonization cascade to construct the challenging propeller-shaped A-B-C ring system as key transformations.

Unraveling antibiotic resistomes associated with bacterial and viral communities in intertidal mudflat aquaculture area

The extensive use of antibiotics in intertidal mudflat aquaculture area has substantially increased the dissemination risk of antibiotic resistance genes (ARGs). As hosts of ARGs, bacteria and virus exert vital effects on ARG dissemination. However, the insights for the interrelationships among ARGs, bacteria, and virus have not been thoroughly explored in intertidal mudflat. Therefore, this study attempts to unravel the occurrence, dissemination, evolution, and driving mechanisms of ARGs associated with bacterial and viral communities using metagenomic sequencing in a typical intertidal mudflat. Abundant and diverse ARGs (22 types and 437 subtypes) were identified and those of ARGs were higher in spring than in autumn. It is worthy noted that virus occupied a more essential position than bacteria for ARGs dissemination through network analysis. Meanwhile, nitrogen exerted indirect effect on ARG profiles by shaping viral and bacterial diversity. According to the results of neutral and null models, deterministic processes dominated the ARG community assembly by controlling sediment nitrogen and antibiotics. Homogeneous and variable selection dominated phylogenetic turnover of ARG community, contributing 46.15% and 45.90% of the total processes, respectively. This study can hence theoretically support for the ARG pollution control and management in intertidal mudflat aquaculture area.

Geological challenges and stabilization strategies for phyllite rock slopes: a case study of Guang-Gansu expressway in Western China

The increased occurrence and severity of natural disasters, such as landslides, have impacted the stability of phyllite rock slopes in the complex geological regions of Western China. This situation presents significant challenges for infrastructure development in the area. This study investigates the upper span bridgehead slope of Guang-Gansu expressway K550 + 031 as a case study to analyze the sliding failure mechanism of thousand rock slopes in the seismic fault zone and the supporting structure failure through field investigation and exploration. The analysis shows that the slope's rock mass is extensively fractured, primarily influenced by the Qingchuan fault zone. This geological activity leads to slope instability, worsened by seasonal rainfall. The phyllite undergoes alternating dry and wet cycles, weakening its mechanical strength, forming cracks, and accelerating slope displacement, subsidence, and cracking. This results in front slope instability, followed by gradual backward and step-by-step traction sliding deformation on both sides. The geological structure and seasonal rainfall damage the original bolt-grid beam-supporting structure. To address this issue, an anti-slide pile combined with a grid beam treatment method is proposed, and its effectiveness is verified through deep displacement monitoring. This study emphasizes the significance of integrating geological structure and seasonal rainfall impacts into infrastructure design within complex geological areas, ensuring slope and supporting structure stability.

Naples prognostic score as a predictor of outcomes in lung cancer: a systematic review and meta-analysis

OBJECTIVE

The Naples prognostic score (NPS) is a newly developed indicator of inflammation and nutritional status. However, its role in predicting the prognosis of lung cancer is unclear. We hereby reviewed the association between NPS and outcomes of lung cancer.

MATERIALS AND METHODS

PubMed, Web of Science, Embase, and Google Scholar were searched up to 15th April 2023 for studies assessing the predictive role of NPS for overall survival (OS) and disease-free survival (DFS) in lung cancer.

RESULTS

Seven studies were included. All were from China. One study was on small cell lung cancer, while the rest were on non-small cell lung cancer. Meta-analysis demonstrated that a high NPS score was a significant predictor of OS (HR: 3.21 95% CI: 2.27, 4.54 I2=62%) and disease-free survival (DFS) (HR: 3.81 95% CI: 2.57, 5.64 I2=65%) in lung cancer patients. Subgroup analysis based on different NPS reference values also showed similar results. The results remained significant on sensitivity analysis.

CONCLUSIONS

The NPS is a strong and independent prognostic indicator of lung cancer patients. Higher NPS scores are associated with worse OS and DFS. Further studies from non-Chinese populations are needed to supplement the results.

Responses of bacterial community and N-cycling functions stability to different wetting-drying alternation frequencies in a riparian zone

Wetting-drying alternation (WD) of the soil is one of the key characteristics of riparian zones shaped by dam construction, profoundly impacting the soil microenvironment that determines the bacterial community. Knowledge concerning the stability of bacterial community and N-cycling functions in response to different frequencies of WD remains unclear. In this study, samples were taken from a riparian zone in the Three Gorges Reservoir (TGR) and an incubation experiment was conducted including four treatments: constant flooding (W), varied wetting-drying alternation frequencies (WD1 and WD2), and constant drying (D) (simulating water level of 145 m, 155 m, 165 m, and 175 m in the riparian zone respectively). The results revealed that there was no significant difference in the diversity among the four treatments. Following the WD1 and WD2 treatments, the relative abundances of Proteobacteria increased, while those of Chloroflexi and Acidobacteriota decreased compared to the W treatment. However, the stability of bacterial community was not affected by WD. Relative to the W treatment, the stability of N-cycling functions estimated by resistance, which refers to the ability of functional genes to adapt to changes in the environment, decreased following the WD1 treatment, but showed no significant change following the WD2 treatment. Random forest analysis showed that the resistances of the nirS and hzo genes were core contributors to the stability of N-cycling functions. This study provides a new perspective for investigating the impacts of wetting-drying alternation on soil microbes.

How nutrient loading leads to alternative stable states in microbially mediated N-cycle pathways: A new insight into bioavailable nitrogen removal in urban rivers

Excessive nutrients have disrupted pathways of microbial-mediated nitrogen (N) cycle in urban rivers and caused bioavailable N to accumulate in sediments, while remedial actions sometimes fail to recover degraded river ecosystems even when environmental quality has been improved. It is not sufficient to revert the ecosystem to its original healthy state by restoring the pre-degradation environmental conditions, as explained by alternative stable states theory. Understanding the recovery of disrupted N-cycle pathways from the perspective of alternative stable states theory can benefit effective river remediation. Previous studies have found alternative microbiota states in rivers; however, the existence and implications of alternative stable states in microbial-mediated N-cycle pathway remain unclear. Here, high-throughput sequencing and N-related enzyme activities measurement were combined in the field investigation to provide empirical evidence for the bi-stability in microbially mediated N-cycle pathways. According to the behavior of bistable ecosystems, the existence of alternative stable states in microbial-mediated N-cycle pathway have been shown, and nutrient loading, mainly total nitrogen and total phosphorus, were identified as key driver of regime shifts. In addition, potential analysis revealed that reducing nutrient loading shifted the N-cycle pathway to a desirable state characterized by high ammonification and nitrification, probably avoiding the accumulation of ammonia and organic N. It should be noted that the improvement of microbiota status can facilitate the recovery of the desirable pathway state according to the relationship between microbiota states and N-cycle pathway states. Keystone species, including Rhizobiales and Sphingomonadales, were discerned by network analysis, and the increase in their relative abundance may facilitate the improvement of microbiota status. The obtained results suggested that the nutrient reduction should be combined with microbiota management to benefit the bioavailable N removal in urban rivers, therefore providing a new insight into alleviating adverse effects of the nutrient loading on urban rivers.

Diversity, abundance and distribution characteristics of potential polyethylene and polypropylene microplastic degradation bacterial communities in the urban river

Carbon chain microplastics, polyethylene (PE), and polypropylene (PP) are the main types of refractory organics. Compared to heterochain microplastics, PE/PP degrading bacterial community and their distribution characteristics in natural rivers are unclear. In this study, the field in situ experiment and indoor enrichment experiment with PE/PP resin as only carbon sources were conducted for a total period of 1150 days. The microbial degradation of pure PE/PP resin was determined by SEM, FTIR, CLSM, GC-MS, and GPC. The Chao 1 index and Invsimpson index of the bacterial community significantly reduced after a series of incubation, demonstrating that the bacterial community was selectively enriched. Empirical core PE/PP degrading bacteria (C-bacteria) and resuscitated PE/PP degrading bacteria (R-bacteria) were screened based on the variation of the abundance of OTUs, and co-occurrence analysis displayed that C-bacteria presented higher betweenness centrality than R-bacteria. The higher abundance and diversity of R-bacteria in biofilms suggest the presence of many rare or low abundance bacteria in natural rivers that may be potential PE/PP degrading bacteria or PE/PP degrading bacteria to be activated, while the lower abundance and diversity of C-bacteria support the slow degradation rate of PE and PP in waters. Compared to the isolated and indicatory PE/PP degrading bacterial genera, the C-bacteria OTUs or genera enriched in this study displayed higher richness and abundance. Enriched PE/PP degrading bacteria occurred in all sampled sites of the Qinhuai River with higher abundance and standard betweenness centrality in sediments (averaging 0.01354 and 0.44421, respectively) than those in overlying water (averaging 0.00536 and 0.17571, respectively), while the highest abundance of degrading bacteria presented in the eutrophic sediments. Inorganic nitrogen was determined to be significantly correlated with the distribution of PE/PP degrading bacteria in sediments via redundancy analysis. This study provides a new perspective on the natural degradation potential of carbon chain microplastics by microbial communities in rivers.

[The performance of digital chest radiographs in the detection and diagnosis of pulmonary nodules and the consistency among readers]

Objective: To investigate the detection and diagnostic efficacy of chest radiographs for ≤30 mm pulmonary nodules and the factors affecting them, and to compare the level of consistency among readers. Methods: A total of 43 patients with asymptomatic pulmonary nodules who consulted in Cancer Hospital, Chinese Academy of Medical Sciences from 2012 to 2014 and had chest CT and X-ray chest radiographs during the same period were retrospectively selected, and one nodule ≤30 mm was visible on chest CT images in the whole group (total 43 nodules in the whole group). One senior radiologist with more than 20 years of experience in imaging diagnosis reviewed CT images and recording the size, morphology, location, and density of nodules was selected retrospectively. Six radiologists with different levels of experience (2 residents, 2 attending physicians and 2 associate chief physicians independently reviewed the chest images and recorded the time of review, nodule detection, and diagnostic opinion. The CT imaging characteristics of detected and undetected nodules on X images were compared, and the factors affecting the detection of nodules on X-ray images were analyzed. Detection sensitivity and diagnosis accuracy rate of 6 radiologists were calculated, and the level of consistency among them was compared to analyze the influence of radiologists' seniority and reading time on the diagnosis results. Results: The number of nodules detected by all 6 radiologists was 17, with a sensitivity of detection of 39.5%(17/43). The number of nodules detected by ≥5, ≥4, ≥3, ≥2, and ≥1 physicians was 20, 21, 23, 25, and 28 nodules, respectively, with detection sensitivities of 46.5%, 48.8%, 53.5%, 58.1%, and 65.1%, respectively. Reasons for false-negative result of detection on X-ray images included the size, location, density, and morphology of the nodule. The sensitivity of detecting ≤30 mm, ≤20 mm, ≤15 mm, and ≤10 mm nodules was 46.5%-58.1%, 45.9%-54.1%, 36.0%-44.0%, and 36.4% for the 6 radiologists, respectively; the diagnosis accuracy rate was 19.0%-85.0%, 16.7%-6.5%, 18.2%-80.0%, and 0%-75.0%, respectively. The consistency of nodule detection among 6 doctors was good (Kappa value: 0.629-0.907) and the consistency of diagnostic results among them was moderate or poor (Kappa value: 0.350-0.653). The higher the radiologist's seniority, the shorter the time required to read the images. The reading time and the seniority of the radiologists had no significant influence on the detection and diagnosis results (P>0.05). Conclusions: The ability of radiographs to detect lung nodules ≤30 mm is limited, and the ability to determine the nature of the nodules is not sufficient, and the increase in reading time and seniority of the radiologists will not improve the diagnostic accuracy. X-ray film exam alone is not suitable for lung cancer diagnosis.

Microbial community structure and denitrification responses to cascade low-head dams and their contribution to eutrophication in urban rivers

Low-head dams are one of the most common hydraulic facilities, yet they often fragment rivers, leading to profound changes in aquatic biodiversity and river eutrophication levels. Systematic assessments of river ecosystem structure and functions, and their contribution to eutrophication, are however lacking, especially for urban rivers where low-head dams prevail. In this study, we address this gap with a field survey on microbial community structure and ecosystem function, in combination with hydrological, environmental and ecological factors. Our findings revealed that microbial communities showed significant differences among the cascade impoundments, which may be due to the environment heterogeneity resulting from the cascade low-head dams. The alternating lentic-lotic flow environment created by the low-head dams caused nutrient accumulation in the cascade impoundments, enhancing environmental sorting and interspecific competition relationships, and thus possibly contributing to the reduction in sediment denitrification function. Decreased denitrification led to excessive accumulation of nutrients, which may have aggravated river eutrophication. In addition, structural equation model analysis showed that flow velocity may be the key controlling factor for river eutrophication. Therefore, in the construction of river flood control and water storage systems, the location, type and water storage capacity of low-head dams should be fully considered to optimize the hydrodynamic conditions of rivers. To summarize, our findings revealed the cumulative effects of cascade low-head dams in an urban river, and provided new insights into the trade-off between construction and decommissioning of low-head dams in urban river systems.

A novel BC/g-C3N4 porous hydrogel carrier used in intimately coupled photocatalysis and biodegradation system for efficient removal of tetracycline hydrochloride in water

Intimately coupled photocatalysis and biodegradation (ICPB) is a promising technology to remove refractory contaminants from water. The key to successful ICPB is a carrier capable of accumulating biofilm and adhering photocatalyst firmly. Herein, BC/g-C₃N₄ was prepared into a three dimensional porous hydrogel and used as a carrier in ICPB system for the first time. Degradation experiments revealed that the removal rate of tetracycline hydrochloride (TCH) in water by the ICPB system was 96.0% after 10 h, which was significantly higher than that by the photocatalysis (PC, 76.3%), biodegradation (B, 32.5%), adsorption (AD, 17.2%), and photolysis (P, 5.0%) systems. Photo-electrochemical tests confirmed that ICPB system had superior electron transfer ability between photocatalysts and microorganisms. The removal efficiency of COD proved that microorganisms played an important role in the mineralization process of TCH by the ICPB system. After the ICPB degradation experiment, microorganisms maintained high activity and Pseudomonas, Burkholderiaceae and Flavobacterium which had TCH degradation or electron transport ability, were enriched. In conclusion, the novel ICPB carrier overcame shortcomings of the traditional ICPB carrier and the novel ICPB system had superior degradation performance for TCH. This study provided a possible method to promote the practical application of ICPB technology.

Diversity and potential functional characteristics of phage communities colonizing microplastic biofilms

The multiple ecological influences and potential microbial degradation of microplastics are generally attributed to the microbial communities colonized on microplastics. Phages play an important role in the composition and function of their bacterial hosts, yet the occurrence and the potential functional characteristics of phages in the biofilms of microplastics have not been known. This study, for the first time, explored the diversity, composition, and potential function characteristics of phage communities living in the biofilms of PP, PE, and PET microplastics and stones, cultured in the same site, via the metagenome method. The results showed that a total of 240 non-redundant virus OTUs (vOTUs), distributed in at least four orders and seven families, were detected from biofilm metagenomes of microplastics. Compared to stones, some phages were selectively enriched by microplastic biofilms, with 13 vOTUs uniquely colonized on three microplastics, and these vOTUs mainly belong to the family Autographiviridae and Podoviridae. Except for the evenness of PP, the richness index, Chao 1 index, and abundance of phage communities of three microplastics were much higher than that of stone. At least 8 bacterial phyla and 72 genera were possibly infected by phages. Compared to the stones, both composition and abundance of the phages and hosts presented significant and strong correlations for three microplastics. Some of the bacterial hosts on microplastics were likely involved in the microplastic degradation, fermenters, nitrogen transformation processes, and so on. A total of 124 encoding auxiliary metabolic genes (AMGs) were detected from viral contigs. The abundance of AMGs in microplastics was much higher than that of stones, which may provide more direct or indirect support for the bacterial degradation of microplastics. This study provides a new perspective on the occurrence and potential functions of phages on microplastic biofilms, thus expanding our understanding of microbial communities on microplastic biofilms.

Trophic interactions regulate microbial responses to environmental conditions and partially counteract nitrogen transformation potential in urban river bends

River bends are distinguished by high biodiversity and elevated rates of biogeochemical activities due to complex hydromorphological processes that form diverse geomorphic units, making it challenging to elucidate the impact of trophic interactions on community assembly and biogeochemical processes. Here, we clarify the effect of trophic interactions in determining the assembly of multi-trophic microbial communities and the impact on nitrogen transformation potential by distinguishing the direct and cascading effects of environmental conditions based on 32 samples collected from a typical urban river bends. It was found that both bacterial and micro-eukaryotic communities were determined by homogeneous selection (indicated by β-nearest taxon index, accounted for 85% and 48.3%, respectively), whereas the dominant environmental factors were different, being sediment particle size (P < 0.05) and nitrogen (P < 0.05), respectively. Both the microbial co-occurrence network and the significant association (P < 0.05) between β-nearest taxon index and trophic transfer efficiency changes showed that the trophic interactions strongly shaped microbial communities in the urban river bends. The path modeling suggested that environmental conditions resulted in an increase in abundance of multi-trophic microbial communities via direct effects (mean standardized effects = 0.21), but reductions in abundance of bacteria via cascading effects, i.e., trophic interaction (mean standardized effects = -0.1). When considering direct and cascading effects together, environmental conditions in urban river bends were found to enhance the abundance of microbial communities, with decreasing magnitude at the higher trophic level. Analogously, the path modeling also indicated the nitrogen transformation potential enhanced by environmental conditions via direct effects, but partly counteracted by trophic interactions via cascading effects. The obtained results could provide a theoretical basis for the regulation and restoration of urban rivers.

Hydrodynamics-driven community coalescence determines ecological assembly processes and shifts bacterial network stability in river bends

Community coalescence, i.e., the mixing and merging of microbial communities and their surrounding environments, is prevalent in various ecosystems and potentially acts on ecological processes. River bends are distinguished by significant cross-stream velocities and spiral flow. The flow in river bends causes the mixing of microbial communities, thus making the resultant community (after mixing) different from its precursors (before mixing) through ecological processes. However, so far, no studies have explored the effect of community coalescence on ecological processes and network stability under the hydrodynamic processes of river bends. Here, we explored bacterial community assembly and community coalescence in river bends by coupling hydrodynamic profiling, aqueous biogeochemistry, DNA sequencing, and ecological theory. The results showed that the water flow dominated the community coalescence by regulating the movement of suspended sediments. The main ecological process determining the bacterial community compositions in water was the dispersal process, whereas in sediments it was the selection process. Furthermore, the negative cohesion results showed that community coalescence determined the stability of bacterial networks through competition and predation. This study depicted the bacterial community coalescence in river bends and highlighted their associations with network stability, which might provide new insights into bacterial community assembly and coalescence under complex hydrodynamics in the aquatic environment.

Effect of water chemistry on nitrogen transformation, dissolved organic matter composition and microbial community structure in hyporheic zone sediment columns

Controlled surface water systems, including those with dams lead to dynamic stage changes that alter the fluctuation directions of flow exchange in the hyporheic zones (HZ). However, the nitrogen transformation, dissolved organic matter (DOM) composition, and microbial community responding to variable scenarios of water source and hyporheic exchange are poorly studied. The present work investigated nitrogen transformation in HZ sediments, focusing on how microbial community structure and biological functions related to nitrogen transformation and sediment-attached DOM compositions. Upwelling of synthesized groundwater, downwelling of synthesized river water and exchangeable elution of both feed water created distinct microbial zonation and N-transformation processes. Mixing of river water and groundwater enhanced microbial diversity, microbial co-occurrence network complexity and N-transformation functions. In terms of the sediment-attached DOM properties after hyporheic exchanges, humic fractions occupied the predominant chromophoric DOM. Correlation analysis implied that there were more DOM properties, e.g., tryptophan-like proteins, humic-like fractions, and the source of humic fractions, involved in affecting the microbial community under downwelling flow. Co-occurrence network analysis verified that fluorescent components, protein-like and lignin-like fractions in sediment-detached DOM were clustered with microbial communities in one module in downwelling column, implying closer interactions among microbial communities and DOM fractions. The strains of Nitrospinae, Dinghuibacter, and Lentimicrobium etc. were key species collaborating to metabolize both nitrogen and DOM in HZ sediments. The work provides insights into how the nitrogen transformation, DOM compositional changes, as well as the linkages between community structure and DOM factions, response to the changes in water chemistry, leading to valuable insights into hyporheic zone functions.

The role of microbial communities on primary producers in aquatic ecosystems: Implications in turbidity stress resistance

Expanding the stress tolerance and adaptation potential of primary producers is of importance for the restoration and management of aquatic ecosystems. Microorganisms have been reported to mediate improved resistance toward different abiotic stresses of primary producers in terrestrial and marine ecosystems. However, it is not clear about the role of microbial communities in the turbidity resistance of primary producers, when aquatic ecosystems are under turbidity pressure. In this study, key microbes and the action path which enhance turbidity tolerance of primary producers were recognized by mesocosm and various multivariate statistical methods. Remarkable decrease of the biomass of primary producers was found with the increase of turbidity. Significant differences in microbial community under different turbidity pressure were recognized and key microbes which may expand the turbidity tolerance of primary producers were further identified. Rhodobacter and Rhodoferax were selected as key microbes by the investigation of keystone species in the microbial ecological network and significant discriminant taxa under different turbidity stress. The action path for microbial communities to help primary producers cope with turbidity pressure was found through structural equation model, and in which the increase of key microbes may expand the turbidity tolerance of primary producers through enhancing the microbial loop. The results may provide a new insight for aquatic ecosystems to resist turbidity stress, and provide a theoretical basis for the management and restoration of aquatic ecosystems.

The Effects of Paroxetine on Benthic Microbial Food Web and Nitrogen Transformation in River Sediments

Paroxetine is a common pharmaceutical to treat depression and has been found to pose threats to aquatic organisms. However, little is known about the effects of paroxetine on the nutrient cycle in aquatic environments. Therefore, DNA metabarcoding is used in this study to analyze the effects of paroxetine on multi-trophic microorganisms and nitrogen transformation in river sediments. Although paroxetine has no significant effect on the diversity of microbenthos, changes in benthic nitrogen-converting bacteria are consistent with the change in the various forms of nitrogen in the sediment, indicating that paroxetine affects the nitrogen conversion process by affecting nitrogen-converting bacteria. In addition, it is found that paroxetine has the ability to influence nitrogen transformation in an indirect way by affecting the trophic transfer efficiency of higher trophic levels (meiofauna and protozoa, protozoa and protozoa), subsequently affecting the growth of nitrogen-converting bacteria through a top-down mechanism (i.e., predation).The results show that paroxetine affects nitrogen transformation directly by affecting nitrogen-converting bacteria and indirectly through top-down effects, emphasizing that the assessment of paroxetine's ecological risks should consider species within different trophic levels.

Depth induced assembly discrepancy of multitrophic microbial communities affect microbial nitrogen transformation processes in river cross-sections

Understanding how the structures and functions of bacterial and microeukaryotic communities vary within cross-sections will improve managements aimed at restoring river ecological functions. However, no comprehensive investigation has examined how microbial community characteristics vary within cross-sections, which makes the accurate calculation and prediction of microbial metabolic processing of substances in rivers difficult. Here, the distributions, co-occurrence networks, and assemblies of bacterial and microeukaryotic communities and their feedback to nitrogen transformation in cross-sections of the Yangtze River were studied by coupling ecological theory, biogeochemistry, and DNA meta-barcoding methods. The study found that depth in cross-sections was the primary driving factor regulating the composition of sediment bacterial and microeukaryotic communities. Co-occurrence network analysis indicated that the effect of bacteria on the co-occurrence network decreased and the network become more simplified and instability with depth in river cross-sections. Quantified using the β-nearest taxon index, the H2 layer sediment (depth 10-20 m) displayed the largest variation in selection processes for microbial assemblies, while homogeneous selection and homogenizing dispersal contributed most to the bacterial and microeukaryotic assemblies in the H3 layer (depth >20 m). Cross-sectional depth and denitrification genes had a significant quadratic correlation, with the highest microbial nitrogen-removal potential occurring in the H2 layer sediment. Structural equation models showed that the sediment nitrogen distributions were regulated by distinct environmental pathways at different depths, and that the H2 layer sediment was primary driven by bacterial community. In this layer, river cross-sectional depth influenced nitrogen transformation by regulating the distribution of sediment particle sizes, which then influenced the assembly of the multitrophic microbial communities. This study will improve river management by clarifying the importance of cross-sectional depth to the ecological function of rivers.

Total Synthesis of (-)-Ceforalide B and (-)-Cephanolides B-D

(-)-Ceforalide B (1) and (-)-cephanolides B-D (2-4) are benzenoid cephanolide diterpenoids possessing the same pentacyclic skeleton, which contains three C13-C15 substituent patterns and different benzylic oxidation states. An olefination/6π-electrocyclization/oxidative aromatization cascade has been verified as divergent access to three C13-C15 patterns. The benzylic aerobic oxidations enabled by the Co(OAc)2·4H2O/bromide salt/O2/PPh3/N-hydroxyphthalimide system have been developed to deliver expected site-selectivity and different oxidation states. Through the divergent strategy, total synthesis of (-)-ceforalide B and (-)-cephanolides B-D is accomplished.

Dam-induced flow velocity decrease leads to the transition from heterotrophic to autotrophic system through modifying microbial food web dynamics

The impoundment of reservoirs changes the river from a riverine heterotrophic system to a lacustrine autotrophic system, which could be attributed to the shift of pelagic microbial food webs in response to the dam-induced disturbances. However, little is known about what is the key factor controlling this variation and how different underlying interactions affect the food web dynamics. This study investigated the effects of flow velocity and nutrient supply on microbial plankton using a microcosm experiment. The results showed that flow velocity decrease was the main factor inducing the detritus-based food web transformed to the autotroph-based food web, with heterotrophic bacteria and protozoan dominated at high velocity, whereas phytoplankton and metazoan were prevalent in the lentic environment. The lentic-acclimated genera, such as Chlorella sp., Mallomonas sp. and Microcystis sp., showed hysteresis after the velocity recovery, suggesting the potential of algae bloom in reservoirs and even downstream of dams. We further conducted a flow-velocity manipulating experiment and constructed a multi-trophic nitrogen cycling model to provide a mechanistic explanation for the microbial food web dynamics and the nitrogen transformation performances. As indicated in model prediction and sensitivity analysis, the abiotic and biotic variations were directly or indirectly controlled by nutrient utilization and predator-prey interactions. Quantification of these bottom-up and top-down forces revealed the buffer role of predators in mitigating the positive effects of nutrient availability on autotrophs at low velocity and on heterotrophs at high velocity, respectively. This study highlights the importance of mastering the whole information of different trophic levels, in order to better capture the complex microbial food web interactions and the consequent biogeochemical processes in river-reservoir systems.

Risk Factors of Benign Stricture of Anastomotic Stoma after Esophagectomy and Therapeutic Effect of Stent Implantation

With the increase in the number of patients and prolongation of their lives after esophagectomy for esophageal cancer, the quality of life after surgery has attracted more and more attention. Although anastomotic stenosis is a common complication, it seriously affects the quality of life and psychological state of patients or even threatens their lives. At present, the exact independent influencing factors of anastomotic stenosis after esophageal cancer surgery have not been determined, and relevant treatment options are still controversial. Here, we analyzed the independent risk factors leading to good postoperative anastomotic stenosis, in order to provide a basis for late prevention. At the same time, we deeply discussed the advantages and safety of stent implantation in the treatment of anastomotic stenosis.

Nutrient status of integrated rice-crayfish system impacts the microbial nitrogen-transformation processes in paddy fields and rice yields

Increasing rice yield is essential for alleviating global food crisis. High soil nutrient level guarantees high rice yields in conventional rice monoculture (RM) systems, but excessive unconsumed nutrients act as pollutants and can even threaten rice growth. The integrated rice-crayfish (IRC) system aims to transfer the excess nutrients from crayfish to paddy fields to improve the comprehensive utilization rate of nutrients and create additional profits, while the responding characteristics of IRC microbial communities in paddy fields and rice yields to the nutrient status remain unclear. Considering the crucial roles of microbiomes in promoting nutrient cycling for crop absorption in rice production progresses, the composition and functional characteristics of soil microbial communities from six IRC farms with variant nutrient statuses in the Yangtze River Delta were surveyed in this study. Compared with RM systems, IRC systems with appropriately improved (p < 0.05) soil quality created favorable nutrient (FN) status accompanied by 15% rice yields increase, while IRC systems with extremely high nutrients (HN) status (p < 0.01) accompanied by 14% rice yields reduction. Soil microbial diversity and network complexity were maintained in FN-IRC systems, but declined in HN-IRC systems, with the Shannon index significantly decreased by 9.2% and network density decreased from 0.135 (in RM) to 0.062. In the FN-IRC systems, the keystone taxa identified by co-occurrence networks displayed inextricably positive correlations with soil nitrification potential (calculated by normalization of amoA gene abundance) and rice yields. While in HN-IRC systems, the large loss of keystone taxa might limit soil nitrogen fixation potential (calculated by normalization of nifH gene abundance), and further rice yields. Our study indicates that soil nutrient management in IRC systems claim attention, and the improvement of nitrogen metabolism is the key to realize agricultural cleaner production.

[Prevalence and risk factors of deep venous thrombosis of lower extremity in patients with stage and pressure ulcers on admission]

Objective: To investigate the incidence and risk factors of deep venous thrombosis (DVT) of lower extremity in patients with stage Ⅲ and Ⅳ pressure ulcer on admission. Methods: A retrospective case series study was conducted. A total of 241 patients with stage Ⅲ and Ⅳ pressure ulcers who met the inclusion criteria and were discharged from the Department of Wound Repair of the First People's Hospital of Zhengzhou from January 1, 2015 to December 31, 2019 were enrolled in this study, including 134 males and 107 females, aged 22 to 93 years, with a median age of 68 years; 37 patients were with stage Ⅲ pressure ulcers and 204 patients were with stage Ⅳ pressure ulcers. The DVT occurrence of patients was recorded. According to whether DVT of lower extremity veins was diagnosed by color Doppler ultrasound within 48 h after admission or not, the patients were divided into DVT group (n=37) and non-DVT group (n=204). Data of patients in the two groups were collected and compared, including gender, age, duration of pressure ulcer, time in bed, and combination with diabetes, hypertension, coronary heart disease, cerebral infarction, pneumonia, sepsis/septic shock, and paraplegia, and the plasma D-dimer level and Caprini score within 24 h after admission. Data were statistically analyzed with independent sample t test, Mann-Whitney U test, chi-square test, and Fisher's exact probability test. The indicators with statistically significant differences between the two groups were analyzed with multivariate logistic regression analysis to screen the independent risk factors influencing the DVT of lower extremity in 241 patients with stage Ⅲ and Ⅳ pressure ulcers on admission. Results: The incidence of DVT of lower extremity was 15.4% (37/241), of which 86.5% (32/37) were asymptomatic DVT. Among the DVT of 46 lower limbs, only 29 involved the inferior genicular veins, accounting for 63.0%. There were no statistically significant differences in gender, duration of pressure ulcer, combination with diabetes, hypertension, coronary heart disease, cerebral infarction, pneumonia, and sepsis/septic shock of patients between the two groups (P>0.05), while there were statistically significant differences in age, time in bed, combination with paraplegia, the plasma D-dimer level and Caprini score of patients between the two groups(t=-3.19, Z=-2.04, χ2=4.44, Z=-3.89, t=-2.14, respectively, P<0.05 or P<0.01). Multivariate logistic regression analysis showed that age and plasma D-dimer level were independent risk factors influencing the DVT of lower extremity in 241 patients with stage Ⅲ and Ⅳ pressure ulcers on admission (with odds ratios of 1.03 and 1.18, respectively, with 95% confidence intervals of 1.00-1.06 and 1.05-1.33, respectively, P<0.05 or P<0.01). Conclusions: The patients with stage Ⅲ and Ⅳ pressure ulcers have a higher incidence of DVT on admission, with age and plasma D-dimer level being the independent risk factors for DVT of lower extremity. It is necessary to pay attention to the targeted screening of DVT and education of its prevention.

Understanding the ecological processes governing hydrophyte-associated bacterial communities involved in hydrophyte growth and development

Maintaining hydrophyte growth has been a major focus of aquatic ecological research. The hydrophyte microbiome plays a key role in the growth and health of hydrophytes, but the ecological processes regulating the assembly and function of hydrophyte microbial communities remain unclear. This knowledge gap limits the efficacy of managing microbiomes to enhance the capacity of hydrophytes to restore the aquatic environment. Here, we sampled three typical hydrophytes (Ceratophyllum demersum, Nymphoides peltatum, and Potamogeton crispus) to study the ecological process governing hydrophyte-associated bacterial communities. The results demonstrated that hydrophyte-associated bacterial communities were affected more by the hydrophyte host species (HEEI = 2.40) than by the environment (HEEI = 1.00). The hydrophyte host species not only affected bacterial community assembly, but reduced the diversity and network complexity of the bacterial community relative to that of the environment. Furthermore, the core taxa of two hydrophytes were identified. Chryseobacterium was the core taxon of N. peltatum, and Burkholderia-Caballeronia-Paraburkholderia, Pseudolabrys, and Pajaroellobacter were the core taxa of P. crispus. The core taxa of P. crispus were closely related to potential denitrification-related functions of bacteria and revealed that P. crispus played a role in denitrification during aquatic ecological restoration. Overall, the results of this study highlight the need to develop approaches employing hydrophyte-associated bacteria to promote the development of hydrophytes, which will be essential for increasing the utility of hydrophyte microbiomes in the future and enhancing aquatic ecological restoration.

New insights into identifying sediment phosphorus sources in river-lake coupled system: A framework for optimizing microbial community fingerprints

Identifying sediment phosphorus sources in river-lake coupled system is a question in developing preferential control strategies for phosphorus. As sediments adsorbed phosphorus and microbes would be transported with changing hydrodynamic, the phosphorus source-specific microbial community fingerprints shed light on determining the major sediment phosphorus sources. However, the identification of microbial community fingerprints is a challenge because both microbial succession and hydrological characteristics of river-lake systems would affect the stability of fingerprints. Therefore, this study provided a framework for optimizing phosphorus source-specific microbial community fingerprints, and attempted to identify the major sources of sediment phosphorus in river-lake coupled ecosystem. Meiliang Lake is one of the highly eutrophic area in Taihu Lake, where the sediments, bacterial communities, and phosphorus had a close relationship. Through analyzing the connectivity of microbes along water continuum, a microbial fingerprints candidate database was constructed. The phosphorus-related bacterial communities were screened and optimized by comparing the difference of predicted results between upstream and downstream, forming the stable microbial community fingerprints which consisted of Bacteroidia, Bacilli, Clostridia, and other species at the class level. SourceTracker results that based on the optimized phosphorus source-specific microbial community fingerprints indicated that the major sediment phosphorus sources to Meiliang Lake were Liangxi River, Wujingang River, and Donghuandi River, with the relative standard deviations ranging from 2.59% to 27.56%. The accuracy of phosphorus source apportionments was further confirmed based on the composite pollution index and hydrodynamic condition. This study put forward suggestions on how to improve the stability of microbial community fingerprints, and would help to improve the understanding of applying microbial source tracking method to identify the sources of abiotic pollution like sediment phosphorus.

A mitochondrial RNA processing protein mediates plant immunity to a broad spectrum of pathogens by modulating the mitochondrial oxidative burst

Mitochondrial function depends on the RNA processing of mitochondrial gene transcripts by nucleus-encoded proteins. This posttranscriptional processing involves the large group of nuclear-encoded pentatricopeptide repeat (PPR) proteins. Mitochondrial processes represent a crucial part in animal immunity, but whether mitochondria play similar roles in plants remains unclear. Here, we report the identification of RESISTANCE TO PHYTOPHTHORA PARASITICA 7 (AtRTP7), a P-type PPR protein, in Arabidopsis thaliana and its conserved function in immunity to diverse pathogens across distantly related plant species. RTP7 affects the levels of mitochondrial reactive oxygen species (mROS) by participating in RNA splicing of nad7, which encodes a critical subunit of the mitochondrial respiratory chain Complex I, the largest of the four major components of the mitochondrial oxidative phosphorylation system. The enhanced resistance of rtp7 plants to Phytophthora parasitica is dependent on an elevated mROS burst, but might be independent from the ROS burst associated with plasma membrane-localized NADPH oxidases. Our study reveals the immune function of RTP7 and the defective processing of Complex I subunits in rtp7 plants resulted in enhanced resistance to both biotrophic and necrotrophic pathogens without affecting overall plant development.

Hydrodynamic zones and the influence of microorganisms on nitrogen transformation in the diverging area of branched rivers

Diverging area is widespread in river networks, and understanding its biogeochemical process characteristics is of great significance to river ecological restoration and environmental quality improvement. Microbial communities affected by hydrodynamics play an important role in biogeochemical processes, but their relationship in diverging area is little known. Here, the composition of microbial community and its feedback to hydrodynamics and nitrogen conversion in the diverging area of river networks were first studied by coupling ecological theory, biogeochemical theory, microbial DNA sequencing and mathematical model of water environment. The results showed that there were five hydrodynamic zones with significant velocity differences in the diverging area, namely low velocity zone, maximum velocity zone, stagnant zone, separation zone, and deflection zone. According to the flow velocity grouping, there were significant differences in the microbial diversity and abundance among low velocity group, maximum velocity group and stagnant group had significant differences (p < 0.05, stress = 0.1207). In the low velocity group, Firmicutes was the dominant phylum which had a highest abundance and may promot the conversion of organic nitrogen into ammonia nitrogen. In the maximum velocity group, Bdellovibrionota was the dominant phylum which had a highest abundance and may promot the conversion of nitrate and nitric oxide to nitrogen. In the stagnant zone, Methylomirabilota was the dominant phylum which had a highest abundance and may promot the conversion of nitrogen into nitrate and ammonium. In addition, dissolved oxygen was the most sensitive environmental factor for shaping microorganisms and nitrogen conversion in the diverging area of the river networks by canonical correlation analysis. The denitrifying bacteria Rhodocyclaceae, was shown to negatively correlated with the flow velocity. This research improves the scientific basis for the study of the ecosystem in river networks, which will guide the construction of river ecological projects.

Effects of long-term exposure to silver nanoparticles on the structure and function of microplastic biofilms in eutrophic water

Microplastics are frequently detected in natural aquatic systems proximate to populated areas, such as urban rivers and lakes, and can be rapidly colonized by microbial communities. Microplastics and silver nanoparticles (AgNPs) share similar pathways into natural waters and tend to form heteroaggregations. However, very little is known about the long-term impacts on the structure and function of microplastic biofilms when chronically exposed to silver nanoparticles. Thus, the present study assessed the accumulation property of AgNPs on polymethyl methacrylate (PMMA) microplastics via adsorption tests and studied the chronic effects of AgNPs on the structure and function of microplastic biofilms via 30-day microcosmic experiments in eutrophic water. The adsorption tests showed that the biofilms-colonized PMMA microplastics presented the highest adsorption of 0.98 mg/g in the 1 mg/L AgNPs microcosms. After the 30-day exposure, lactic dehydrogenase release and reactive oxygen species generation of PMMA biofilms increased by 33.23% and 23.98% compared to the MPs-control group with no-AgNPs, indicating that the number of dead cells colonizing microplastics significantly increased. Network analysis suggested that the stabilization of the bacterial community declined with the long-term exposure to AgNPs through the reduction of the modularity and average path length of the network. Compared to the MPs-control group, long-term exposure to AgNPs caused cumulatively inhibitory effects on the nitrogen removal and the N₂O emissions in eutrophic water. The isotopomer analysis revealed that the contribution rate of NO₂^- reduction to N₂O emissions was gradually increasing with the AgNPs exposure. Real-time PCR analysis showed that denitrification genes were less sensitive to AgNPs than the nitrification genes, with gene nosZ performed the most negligible response. Overall, our results revealed that long-term exposure to AgNPs could alter biogeochemical cycling involved by microplastic biofilms and cumulatively reduce the self-recovery of the eutrophic ecosystem.

Determination of the direct and indirect effects of bend on the urban river ecological heterogeneity

The ecological heterogeneity created by river bends benefits the diversity of microorganisms, which is vital for the pollutant degradation and overall river health. However, quantitative tools capable of determining the interactions among different trophic levels and species are lacking, and research regarding ecological heterogeneity has been limited to a few species. By integrating the multi-species-based index of biotic integrity (Mt-IBI) and the structure equation model (SEM), an interactions-based prediction modeling framework was established. Based on DNA metabarcoding, a multi-species (i.e., bacteria, protozoans, and metazoans) based index of biotic integrity including 309 candidate metrics was developed. After a three-step screening process, eight core metrics were obtained to assess the ecological heterogeneity, quantitatively. The Mt-IBI value, which ranged from 2.08 to 7.17, was calculated as the sum of each single core metric value. The Mt-IBI revealed that the ecological heterogeneity of concave banks was higher than other sites. According to the result of the SEM, D₉₀ was the controlling factor (r = -0.779) of the ecological heterogeneity under the influence of the river bends. The bend-induced redistribution of sediment particle further influenced the concentrations of carbon, nitrogen, and sulphur. The nitrogen group (r = 0.668) also played an essential role in determining the ecological heterogeneity, follow by carbon group (r = 0.455). Furthermore, the alteration of niches would make a difference on the ecological heterogeneity. This multi-species interactions-based prediction modeling framework proposed a novel method to quantify ecological heterogeneity and provided insight into the enhancement of ecological heterogeneity in river bends.

Eutrophication dangers the ecological status of coastal wetlands: A quantitative assessment by composite microbial index of biotic integrity

The intertidal wetland ecosystem is vulnerable to environmental and anthropogenic stressors. Understanding how the ecological statuses of intertidal wetlands respond to influencing factors is crucial for the management and protection of intertidal wetland ecosystems. In this study, the community characteristics of bacteria, archaea and microeukaryote from Jiangsu coast areas (JCA), the longest muddy intertidal wetlands in the world, were detected to develop a composite microbial index of biotic integrity (CM-IBI) and to explore the influence mechanisms of stresses on the intertidal wetland ecological status. A total of 12 bacterial, archaea and microeukaryotic metrics were determined by range, responsiveness and redundancy tests for the development of ba-IBI, ar-IBI and eu-IBI. The CM-IBI was further developed via three sub-IBIs with weight coefficients 0.40, 0.33 and 0.27, respectively. The CM-IBI (R² = 0.58) exhibited the highest goodness of fit with the CEI, followed by ba-IBI (R² = 0.36), ar-IBI (R² = 0.25) and eu-IBI (R² = 0.21). Redundancy and random forest analyses revealed inorganic nitrogen (inorgN), total phosphorus (TP) and total organic carbon (TOC) to be key environmental variables influencing community compositions. A conditional reasoning tree model indicated the close associating between the ecological status and eutrophication conditions. The majority of sites with water inorgN<0.67 mg/L exhibited good statuses, while the poor ecological status was observed for inorgN>0.67 mg/L and TP > 0.11 mg/L. Microbial networks demonstrated the interactions of microbial taxonomic units among three kingdoms decreases with the ecological degradation, suggesting a reduced reliability and stability of microbial communities. Multi-level path analysis revealed fishery aquaculture and industrial development as the dominant anthropogenic activities effecting the eutrophication and ecological degradation of the JCA tidal wetlands. This study developed an efficient ecological assessment method of tidal wetlands based on microbial communities, and determined the influence of human activities and eutrophication on ecological status, providing guidance for management standards and coastal development.

New insights into nitrogen removal potential in urban river by revealing the importance of microbial community succession on suspended particulate matter

The importance of suspended particulate matter (SPM) in nitrogen removal from aquatic environments has been acknowledged in recent years by recognizing the role of attached microbes. However, the succession of attached microbes on suspended particles and their role in nitrogen removal under specific surface microenvironment are still unknown. In this study, the causation among characteristics of SPM, composition and diversity of particle-attached microbial communities, and abundances of nitrogen-related genes in urban rivers was firstly quantitatively established by combing spectroscopy, 16 S rRNA amplicon sequencing, absolute gene quantification and supervised integrated machine learning. SPM in urban rivers, coated with organic layers, was mainly composed of silt and clay (87.59-96.87%) with D50 (medium particle size) of 8.636-30.130 μm. In terms of material composition of SPM, primary mineral was quartz and the four most abundant elements were O, Si, C, Al. The principal functional groups on SPM were hydroxyl and amide. Furthermore, samples with low, medium and high levels of ammoxidation potential were classified into three groups, among which significant differences of microbial communities were found. Samples were also separated into three groups with low, medium and high levels of denitrification potential and significant differences occurred among groups. The particle size, content of functional groups and concentration of SPM were identified as the most significant factors related with microbial communities, playing an important role in succession of particle-attached microbes. In addition, the path model revealed the significantly positive effect of organic matter and particle size on the microbial communities and potential nitrogen removal. The content of hydroxyl and temperature were identified as the most effective predicting factors for ammoxidation potential and denitrification potential respectively by Random Forests Regression models, which had good predictive performances for potential of ammoxidation (R² = 0.71) and denitrification (R² = 0.61). These results provide a basis for quickly assessing the ability of nitrogen removal in urban rivers.

Pollution gradients shape the co-occurrence networks and interactions of sedimentary bacterial communities in Taihu Lake, a shallow eutrophic lake

The co-occurrence networks and interactions of bacterial communities in sediments are highly variable with environmental factors, which are vital to the nutrient biogeochemical cycle, pollutants biodegradation, and microbial community stability in lake ecosystems. Although pollution gradients reflect environmental variation comprehensively, few studies have characterized the changes in co-occurrence networks and interactions of bacterial communities along sediment pollution gradients. In order to investigate the impact of pollution gradients on compositions, co-occurrence networks, and interactions of sedimentary microbial communities, we studied the bacterial communities in the sediments of a typical shallow eutrophic lake, Taihu Lake, along pollution gradients using 16S rRNA gene high-throughput sequencing technology. All the sediment sampling sites were classified into mild, moderate, and severe pollution groups according to the sediments' physicochemical properties. Our results showed that the taxon richness was lowest in the severe pollution group, and the diversity of species decreased with the level of pollution. The complexity of the co-occurrence network decreased as the level of pollution increased, and the severe pollution group was characterized by a small-world network. The relative abundance of Proteobacteria, Bacteroidetes, and Chlorobi increased significantly as the level of pollution increased (P < 0.05). Strong inter-phyla co-occurrence or co-exclusion patterns demonstrated that the strength of interactions was enhanced in the severe pollution group, indicating stronger cooperative or competitive relationships. Chloroflexales and Chlorobiales were unique keystone taxa in the severe pollution group. The results of this study indicate that severe pollution reduces microbial diversity and network complexity, which may lead to community instability. The competition for nutrients of some copiotrophic bacteria may be enhanced as the level of pollution increased. The unique keystone taxa may contribute to photosynthesis and pollutant degradation in the severe pollution group. These findings expand our understanding of variation in bacterial co-occurrence networks and interactions along sediment pollution gradients.

Predicting bend-induced heterogeneity in sediment microbial communities by integrating bacteria-based index of biotic integrity and supervised learning algorithms

Prioritizing the relationship between heterogeneity of sediment habitats and river bends is critical when planning and reconstructing urban rivers. However, the exact relationship between ecological heterogeneity and river bends remains ambiguous. Therefore, this research proposed a new approach to quantify and predict bend-induced ecological heterogeneity, incorporating the bacteria-based index of biotic integrity (Ba-IBI), path model, and random forest regression model. The developed Ba-IBI quantified heterogeneity in sediment microbial communities, ranging from low (1.40) to high (3.97). A path model was developed and validated in order to further investigate the relative contributions of environmental factors to the Ba-IBI. The established path model, which was considered acceptable with a CMIN/df = 1.949 < 4, suggested that primary environmental factors affecting the sediment bacterial communities were flow velocity and ammonium concentration in sediment. To further characterize the relationship between environmental factors and the Ba-IBI, a function was constructed using the random forest regression model that predicts the responses of sediment bacterial communities to environmental factors with R² = 0.6126. The proposed approach and prediction tools will provide knowledge to improve natural channel design and post-project evaluations in river restoration projects.

Effects of nitrogen on the longitudinal and vertical patterns of the composition and potential function of bacterial and archaeal communities in the tidal mudflats

Increasing attention has been focused on the diminishing health of coastal ecosystems. Understanding the effects of eutrophication on tidal flat ecosystems is beneficial for the restoration and management of coastal ecosystems. However, previous studies did not consider the effects of nitrogen on the structure and function of bacterial and archaeal communities in longitudinal and vertical profiles. Here, the diversity, composition, assembly mechanism, and potential metabolic function of the bacterial and archaeal communities were studied in two longitudinal tidal sections at different eutrophic levels. Nitrogen and salinity were the critical factors that influenced the bacterial and archaeal community composition using canonical correspondence and multivariate regression tree analyses. For the bacterial community, the higher nitrogen loading in tidal mudflats resulted in the convergence of diversity and structure in the longitudinal profile of bacteria, but divergence was detected in the vertical profile. For archaea, the diversity tended to be convergent in longitudinal and vertical profiles in the higher nitrogen area, but the change of structure was similar to that of bacteria. Besides the homogeneous processes influenced by salinity, the assembly process of the bacterial community was mainly influenced by heterogeneous selection (34.8%) and that of archaea by dispersal limitation (19.5%). However, the bacterial and archaeal communities in the higher nitrogen section presented more of an influence of heterogeneous selection (respectively, 39 and 5.6%) than that of the lower nitrogen section (respectively, 10 and 0.2%). Structural equation modeling indicated that nitrogen may have inhibited the effects of the bacterial community on nitrogen turnover in nitrogen-rich anoxic sediment environments, but may have strengthened the effect of the archaeal community on carbon metabolism compared to bacteria. This work deepens our understanding of the responses of bacterial and archaeal community structure and potential function to nitrogen pollution in tidal mudflats.

Propelling the practical application of the intimate coupling of photocatalysis and biodegradation system: System amelioration, environmental influences and analytical strategies

The intimate coupling of photocatalysis and biodegradation (ICPB) possesses an enhanced ability of recalcitrant contaminant removal and energy generation, owing to the compact communication between biotic components and photocatalysts during the system operation. The photocatalysts in the ICPB system could dispose of noxious contaminants to relieve the external pressure on microorganisms which could realize the mineralization of the photocatalytic degradation products. However, due to the complex components in the composite system, the mechanism of the ICPB system has not been completely understood. Moreover, the variable environmental conditions would play a significant role in the ICPB system performance. The further development of the ICPB scheme requires clarification on how to reach an accurate understanding of the system condition during the practical application. This review starts by offering detailed information on the system construction and recent progress in the system components' amelioration. We then describe the potential influences of relevant environmental factors on the system performance, and the analytical strategies applicable for comprehending the critical processes during the system operation are further summarized. Finally, we put forward the research gaps in the current system and envision the system's prospective application. This review provides a valuable reference for future researches that are devoted to assessing the environmental disturbance and exploring the reaction mechanisms during the practical application of the ICPB system.

Assessing the effects of cascade dams on river ecological status using multi-species interaction-based index of biotic integrity (Mt-IBI)

Cascade dams have exerted significant effects on river ecosystems. To quantitatively assess dam-induced effects on river ecological status, a novel multi-species interaction-based index of biotic integrity (Mt-IBI) was developed. Benthic microbiota was selected as a bio-indicator for its sensitivity to the environmental disturbance. An environmental DNA metabarcoding tool was used to identify microbiota (bacteria, protozoan, and metazoan). The Mt-IBI was applied to assess the ecological status of the Hanjiang River, a representative dam-affected river in China. Fifteen sampling sites along the Hanjiang River were sampled in June 2018. Seven core metrics were screened from a total of 364 candidate metrics to calculate the value of the Mt-IBI. The Mt-IBI of the Hanjiang River ranged from 1.90 to 6.39, with a mean value of 4.02. The mean values of Mt-IBI at the reservoir and riverine side of dams were 2.11 and 3.81, respectively. The downstream reach without dam constructions had the highest mean Mt-IBI (5.79). Thus, the continuity of the river was strongly related to the Mt-IBI. Structural equation models (SEMs) were further established to identify the dominant environmental variables in the dam-affected river. The SEMs indicated that flow velocity (coefficient 0.749) was the most important determinant of ecological status in the Hanjiang River. Water organic matter also played a vital role in determining the ecological status of the Hanjiang River, and exerted the strongest direct effect (P < 0.001, r = 0.712). The reliability of SEMs was verified by building a support vector regression model (R² = 0.8141). This study can provide new tools for ecological assessment and diagnosis, and provide a new perspective for the management of cascade dams.

Nitrogen cycling processes and the role of multi-trophic microbiota in dam-induced river-reservoir systems

The nitrogen (N) cycle is one of the most important nutrient cycles in river systems, and it plays an important role in maintaining biogeochemical balance and global climate stability. One of the main ways that humans have altered riverine ecosystems is through the construction of hydropower dams, which have major effects on biogeochemical cycles. Most previous studies examining the effects of damming on N cycling have focused on the whole budget or flux along rivers, and the role of river as N sources or sinks at the global or catchment scale. However, so far there is still lack of comprehensive and systematic summarize on N cycling and the controlling mechanisms in reservoirs affected by dam impoundment. In this review, we firstly summarize N cycling processes along the longitudinal riverine-transition-lacustrine gradient and the vertically stratified epilimnion-thermocline-hypolimnion gradient. Specifically, we highlight the direct and indirect roles of multi-trophic microbiota and their interactions in N cycling and discuss the main factors controlling these biotic processes. In addition, future research directions and challenges in incorporating multi-trophic levels in bioassessment, environmental flow design, as well as reservoir regulation and restoration are summarized. This review will aid future studies of N fluxes along dammed rivers and provide an essential reference for reservoir management to meet ecological needs.

RNA m1A Methyltransferase TRMT6 Predicts Poorer Prognosis and Promotes Malignant Behavior in Glioma

Background: Glioma is the most prevalent central nervous system tumor in humans, and its prognosis remains unsatisfactory due to a lack of effective therapeutic targets. The ectopic expression of N1-methyladenosine (m1A) regulators is a key participant in tumorigenesis and progression. However, the m1A regulator expression status, prognostic value, and relationship with tumor clinical features in glioma remain unclear. Methods: Public datasets were used to analyze the mRNA and protein expression levels of m1A regulators. Kaplan-Meier and Cox regression analyses were performed to confirm the prognostic value of m1A regulators in glioma. Cellular experiments were conducted to verify the effect of TRMT6 on cell function. A comprehensive bioinformatics analysis was conducted to identify the potential molecular mechanisms regulated by TEMT6 in glioma. Results: We found that the dysregulation of m1A regulators was closely associated with tumorigenesis and progression in glioma. Furthermore, TRMT6 might be a powerful and independent biomarker for prognosis in glioma. Our study showed that inhibition of TRMT6 suppressed the proliferation, migration, and invasion of glioma cells. Mechanistically, TRMT6 may be involved in glioma progression by regulating cell cycle, PI3K-AKT, TGF-beta, MTORC1, NOTCH, and MYC pathways. Conclusions: Variation in m1A regulators was closely associated with malignant progression in glioma. Silencing TRMT6 suppressed the cell proliferation, migration, and invasion in glioma. m1A regulators, especially TRMT6, might play an essential role in the malignant progression of glioma.

Bacterial contribution to 17β-estradiol mineralization in lake sediment as revealed by 13C-DNA stable isotope probing

The accumulation of estrogens in aquatic environments has drawn increasing public concern due to their adverse effects on aquatic ecosystems and human health. Bacteria play important roles in eliminating estrogens from the environment, but knowledge of the identity and functions of the microorganisms involved in metabolizing these steroid hormones in the natural microbial communities is lacking. Here, we added ¹³C-17β-estradiol (¹³C-E2) to sediments collected from Zhushan (ZS) Bay, Meiliang (ML) Bay, Gonghu (GH) Bay, and the central area (CA) of the Taihu Lake. The indigenous assimilators of E2 in the sediments were recognized using ¹³C-DNA stable isotope probing (DNA-SIP), and their effects on ¹³C-E2 mineralization were studied under aerobic condition. During the 30-day incubation period, ZS Bay had the highest cumulative percentage of ¹³C-E2 mineralization to ¹³CO₂ (65.5%), while CA presented the lowest (51.4%). Based on DNA-SIP, we saw that Novosphingobium, Ralstonia, Pseudomonas, Sphingomonas, Nitrosomonas, and Alcaligenes were involved in E2-derived ¹³C assimilation for the entire incubation period. Acinetobacter, Flavobacterium, and Mycobacterium only assimilated ¹³C for the first half of the incubation. H16 was identified as an E2 assimilator for the first time in this study. In addition, the temporal changes in assimilator abundances during the incubation period indicated that these genera played dominant roles at different stages in the process of E2 biodegradation. The bacteria engaged in the assimilation of E2 in situ were identified, and the rate of increase in the relative abundance of assimilators was significantly (P < 0.05) and positively correlated with the E2 mineralization in sediments. This information enhances our knowledge of in situ E2 biodegradation and provides a potential resource that could be used to eliminate estrogens in sediments.

Effects of black carbon-based thin-layer capping for nitrogen-overloaded sediment remediation on microbial community assembly

Black carbon is considered as a promising material for thin-layer capping for sediment remediation. However, the effects of black carbon-based thin-layer capping on microbial communities have not been thoroughly studied. Here, the preparation conditions of capping material were optimized, and the interaction and assembly mechanisms of the microbial community in sediment under black carbon capping were studied. The results showed that concentration of NH₄⁺-N in the overlying water was stably lower than 0.5 mg/L after capping. The abundance of key genes related to nitrogen transformation in the sediment was increased. Denitrification was the dominant nitrogen removal pathway under coarse granule capping, while aromatic compound degradation was dominant under fine granule capping and dissimilatory N reduction to ammonium was regarded as the dominant nitrogen removal pathway. Community assembly was mainly driven by deterministic processes (≥ 80%). Interactions between rare and common operational taxonomic units were most frequent. The functional zoning of nitrogen transformation in the vertical aerobic, hypoxic, and anaerobic zones of the sediment was strengthened because of black carbon capping. Overall, these results expand our current understanding of the ecological significance of black carbon capping for remediating contaminated sediment.