Malignant clonal evolution drives multiple myeloma cellular ecological diversity and microenvironment reprogramming.

BACKGROUND: Multiple myeloma (MM) is a heterogeneous disease with different patterns of clonal evolution and a complex tumor microenvironment, representing a challenge for clinicians and pathologists to understand and dissect the contribution and impact of polyclonality on tumor progression. METHODS: In this study, we established a global cell ecological landscape of the bone marrow (BM) from MM patients, combining single-cell RNA sequencing and single-molecule long-read genome sequencing data. RESULTS: The malignant mutation event was localized to the tumor cell clusters with shared mutation of ANK1 and IFITM2 in all malignant subpopulations of all MM patients. Therefore, these two variants occur in the early stage of malignant clonal origin to mediate the malignant transformation of proplasmacytes or plasmacytes to MM cells. Tumor cell stemness index score and pseudo-sequential clonal evolution analysis can be used to divide the evolution model of MM into two clonal origins: types I and IX. Notably, clonal evolution and the tumor microenvironment showed an interactive relationship, in which the evolution process is not only selected by but also reacts to the microenvironment; thus, vesicle secretion enriches immune cells with malignant-labeled mRNA for depletion. Interestingly, microenvironmental modification exhibited significant heterogeneity among patients. CONCLUSIONS: This characterization of the malignant clonal evolution pattern of MM at the single-cell level provides a theoretical basis and scientific evidence for a personalized precision therapy strategy and further development of a potential new adjuvant strategy combining epigenetic agent and immune checkpoint blockade.

(Epi)genomic adaptation driven by fine geographical scale environmental heterogeneity after recent biological invasions.

Elucidating processes and mechanisms involved in rapid local adaptation to varied environments is a poorly understood but crucial component in management of invasive species. Recent studies have proposed that genetic and epigenetic variation could both contribute to ecological adaptation, yet it remains unclear on the interplay between these two components underpinning rapid adaptation in wild animal populations. To assess their respective contributions to local adaptation, we explored epigenomic and genomic responses to environmental heterogeneity in eight recently colonized ascidian (Ciona intestinalis) populations at a relatively fine geographical scale. Based on MethylRADseq data, we detected strong patterns of local environment-driven DNA methylation divergence among populations, significant epigenetic isolation by environment (IBE), and a large number of local environment-associated epigenetic loci. Meanwhile, multiple genetic analyses based on single nucleotide polymorphisms (SNPs) showed genomic footprints of divergent selection. In addition, for five genetically similar populations, we detected significant methylation divergence and local environment-driven methylation patterns, indicating the strong effects of local environments on epigenetic variation. From a functional perspective, a majority of functional genes, Gene Ontology (GO) terms, and biological pathways were largely specific to one of these two types of variation, suggesting partial independence between epigenetic and genetic adaptation. The methylation quantitative trait loci (mQTL) analysis showed that the genetic variation explained only 18.67% of methylation variation, further confirming the autonomous relationship between these two types of variation. Altogether, we highlight the complementary interplay of genetic and epigenetic variation involved in local adaptation, which may jointly promote populations' rapid adaptive capacity and successful invasions in different environments. The findings here provide valuable insights into interactions between invaders and local environments to allow invasive species to rapidly spread, thus contributing to better prediction of invasion success and development of management strategies.

Long-term survival outcomes of patients with primary ocular adnexal MALT lymphoma: A large single-center cohort study.

BACKGROUND: Primary ocular adnexal extranodal marginal zone mucosa-associated lymphoid tissue lymphoma (OAML) is a rare subtype of non-Hodgkin's lymphoma, and no consensus has been defined concerning the optimal treatment strategies. This study aims to investigate the associations of disease characteristics and different treatments with long-term outcomes of patients with localized OAML. METHODS: A large retrospective cohort study was conducted in a single-center of China, and 166 patients with newly diagnosed primary localized OAML were enrolled. Detailed data of disease characteristics at diagnosis and treatments were collected for all patients. We compared treatment response and progression-free survival (PFS) among patients with different characteristics and treatments. RESULTS: Of the 166 patients, 52 received complete resection of neoplasm, whereas 114 had residual lesion after surgery. Among the 114 patients, 61 underwent watchful waiting and 53 received further treatment including localized radiotherapy, chemotherapy, or combined radiotherapy and chemotherapy. Median follow-up was 49 months. A total of 31 patients had disease progression or relapse, including four patients with such event more than five years after initial treatment. The 5-year PFS was 73.9%, 70.6%, and 85.9%, whereas the 10-year PFS was 69.3%, 59.2%, and 79.3%, among patients with complete resection of neoplasm, patients in the watchful waiting group and patients with further treatment, respectively. Patients with further treatment had longer PFS, compared with patients in the watchful waiting group (p = 0.011). Bilateral involvement at diagnosis was associated with significantly inferior PFS (p = 0.029), whereas age, IPI score, or TNM staging were not associated with PFS. No serious adverse reaction was reported among patients with further treatment. CONCLUSIONS: Bilateral involvement was associated with poor prognosis. Among patients with residual lesions after surgery, further treatment was associated with improved survival. Patients with OAML might experience disease progression or relapse more than five years after initial treatment.

Disparities in stage at diagnosis for liver cancer in China.

Background: The stage at diagnosis is a major factor in making treatment strategies and cancer control policies. However, the stage distribution for liver cancer in China was not well studied. In this multi-center hospital-based study, we aimed to identify the distribution and factors associated with stage at diagnosis for liver cancer in China. Methods: We included patients diagnosed with primary liver cancer in 13 hospitals of 10 provinces covering various geographic and socioeconomic populations during 2016-2017 in China. The stage distribution overall, and by sex and age at diagnosis were analyzed. We used logistic regression to identify the factors associated with stage III-IV disease. We further compared these estimates with data from the USA. Results: We included 2,991 patients with known stage at diagnosis in China. The proportion of patients diagnosed with stage I, II, III, and IV was 17.5%, 25.6%, 29.3%, and 27.6%, respectively. The proportion of stage III-IV cases was higher in women [65.1% vs 54.9%, adjusted odds ratio (OR) = 1.5, 95% CI: 1.2, 1.8] and those ≥ 60 years (61.6% vs 52.8%, OR = 1.4, 95% CI: 1.2, 1.6). We found an increased risk of stage III-IV among drinkers and those without a family history of cancer. Compared to the USA, our study population had a substantially higher proportion of stage III-IV cases (56.9% vs 45.6%). Conclusion: The disparities in liver cancer stage at diagnosis among different populations within China, and between China and the USA, imply the necessity for improving cancer awareness and early detection for liver cancer in China.

Performance and effectiveness of hepatocellular carcinoma screening in individuals with HBsAg seropositivity in China: a multicenter prospective study.

Current guidelines recommend hepatocellular carcinoma (HCC) surveillance for at-risk individuals, including individuals with hepatitis B virus infection. However, the performance and survival benefits of annual screening have not been evaluated through multicenter prospective studies in a Chinese population. Between 2017 and 2021, we included 14,426 participants with hepatitis B surface antigen seropositivity in an annual HCC screening study in China using a multicenter prospective design with ultrasonography and serum alpha-fetoprotein. After four rounds of screening and follow-up, the adjusted hazard ratios of death after correction for lead-time and length-time biases for screen-detected cancers at the prevalent and incident rounds were 0.74 (95% confidence interval = 0.60-0.91) and 0.52 (95% confidence interval = 0.40-0.68), respectively. A meta-analysis demonstrated that HCC screening was associated with improved survival after adjusting for lead-time bias. Our findings highlight the 'real-world' feasibility and effectiveness of annual HCC screening in community settings for the early detection of HCC and to improve survival.

Survival differences between the USA and an urban population from China for all cancer types and 20 individual cancers: a population-based study.

Background: The systematic comparison of cancer survival between China and the USA is rare. Here we aimed to assess the magnitude of survival disparities and disentangle the impact of the stage at diagnosis between a Chinese metropolitan city and the USA on cancer survival. Methods: We included 11,046 newly diagnosed cancer patients in Dalian Cancer Registry, China, 2015, with the follow-up data for vital status until December 2020. We estimated age-standardised 5-year relative survival and quantified the excess hazard ratio (EHR) of death using generalised linear models for all cancers and 20 individual cancers. We compared these estimates with 17 cancer registries' data from the USA, using the Surveillance, Epidemiology, and End Results database. We further estimated the stage-specific survival for five major cancers by region. Findings: Age-standardised 5-year relative survival for all patients in Dalian was lower than that in the USA (49.9% vs 67.9%). By cancer types, twelve cancers with poorer prognosis were observed in Dalian compared to the USA, with the largest gap seen in prostate cancer (Dalian: 55.8% vs USA: 96.0%). However, Dalian had a better survival for lung cancer, cervical cancer, and bladder cancer. Dalian patients had a lower percentage of stage Ⅰ colorectal cancer (Dalian: 17.9% vs USA: 24.2%) and female breast cancer (Dalian: 40.9% vs USA: 48.9%). However, we observed better stage-specific survival among stage Ⅰ-Ⅱ lung cancer patients in Dalian than in the USA. Interpretation: This study suggests that although the overall prognosis for patients was better in the USA than in Dalian, China, survival deficits existed in both countries. Improvement in cancer early detection and cancer care are needed in both countries. Funding: National Key R&D Program (2021YFC2501900, 2022YFC3600805), Major State Basic Innovation Program of the Chinese Academy of Medical Sciences (2021-I2M-1-010, 2021-I2M-1-046), and Talent Incentive Program of Cancer Hospital of Chinese Academy of Medical Sciences.

Neighbours matter: Effects of genomic organization on gene expression plasticity in response to environmental stresses during biological invasions.

Gene expression regulation has been widely recognized as an important molecular mechanism underlying phenotypic plasticity in environmental adaptation. However, it remains largely unexplored on the effects of genomic organization on gene expression plasticity under environmental stresses during biological invasions. Here, we use an invasive model ascidian, Ciona robusta, to investigate how genomic organization affects gene expression in response to salinity stresses during range expansions. Our study showed that neighboring genes were co-expressed and approximately 30% of stress responsive genes were physically clustered on chromosomes. Such coordinated expression was substantially affected by the physical distance and orientation of genes. Interestingly, the overall expression correlation of neighboring genes was significantly decreased under high salinity stresses, illustrating that the co-expression regulation could be disrupted by salinity challenges. Furthermore, the clustering of genes was associated with their function constraints and expression patterns - operon genes enriched in gene expression machinery had the highest transcriptional activity and expression stability. Notably, our analyses showed that the tail-to-tail genes, mainly involved in biological functions related to phosphorylation, homeostatic process, and ion transport, exhibited higher intrinsic expression variability and greater response to salinity challenges. Altogether, the results obtained here provide new insights into the effects of gene organization on gene expression plasticity under environmental challenges, hence improving our knowledge on mechanisms of rapid environmental adaptation during biological invasions.

New onset of type 2 diabetes after colorectal cancer diagnosis: Results from three prospective US cohort studies, systematic review, and meta-analysis.

BACKGROUND: Limited data indicate that patients with colorectal cancer (CRC) are at higher risk of developing type 2 diabetes (T2D). We prospectively examined the risk of T2D between individuals with and without CRC in three large cohorts and conducted a meta-analysis. METHODS: We assessed the diagnosis of CRC and T2D among 111,485 women from the Nurses' Health Study, 112,958 women from the Nurses' Health Study II, and 46,581 men from the Health Professionals Follow-up Study. We used multivariable Cox regression with time-varying covariates to calculate the hazard ratio (HR) of T2D in relation to CRC diagnosis. We further performed a systematic review and meta-analysis of cohort studies. FINDINGS: Up to 36 years of follow-up (6.9 million person-years), we documented 3402 incident CRC cases and 26,469 T2D cases. Compared to non-CRC individuals, those with CRC were more likely to develop T2D (multivariable-adjusted HR 1.20, 95% CI 1.05-1.38). The association was most evident for individuals with fewer risk factors for T2D. In the meta-analysis of seven cohort studies (1,061,744 participants), CRC was associated with higher T2D risk (meta-analysis HR 1.21, 95% CI 1.11-1.31, I2 = 57.9%). By CRC duration, a statistically significant association was observed in the first 10 years but not after 10 years of CRC diagnosis (≤5 years, meta-analysis HR 1.32, 95% CI 1.27-1.36; 5.1-10 years, 1.14 [1.04-1.25]; >10 years, 1.14 [0.91-1.37]). INTERPRETATION: CRC was associated with increased T2D risk, especially in the first ten years after CRC diagnosis. Our findings highlight the importance of T2D prevention for CRC survivorship care. FUNDING: NHS cohort infrastructure grant (UM1 CA186107), NHS program project grant that funds cancer research (P01 CA87969), NHS II cohort infrastructure grant (U01 CA176726), HPFS cohort infrastructure grant (U01 CA167552) and the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (2021-I2M-1-010).

National Cancer Data Linkage Platform of China: Design, Methods, and Application.

Background: The National Cancer Center (NCC) and China CDC cooperatively designed a National Cancer Data Linkage (NCDL) Platform to fulfill the task of sharing cancer outcome data through an automatic web-based system. Methods: NCC and China CDC established a web-based NCDL Platform to link death information from China CDC with the cancer database from NCC. Overall, 76,708 cancer patients' data were analyzed to assess the feasibility and match rate of the NCDL Platform for 7 major cancers. Results: The function of the platform includes a data application and approval system, data linkage module, and results visualization system. Through the platform, 38.9% cases were identified as deaths cases from the NCDL Platform in the first 3 years after cancer diagnosis. The linkage rate was highest in liver cancer and lowest in breast cancer. Conclusions: The NCDL Platform provides a powerful and efficient way to link national vital statistics with national cancer programs' data. Expanding cancer outcome data linkage may not only improve data collection efficiency, but also improve data use.

Identification of DNA (de)methylation-related genes and their transcriptional response to environmental challenges in an invasive model ascidian.

Marine invasive species are constantly challenged by acute or recurring environmental stresses during their range expansions. DNA methylation-mediated stress memory has been proposed to effectively affect species' response and enhance their overall performance in recurring environmental challenges. In order to further test this proposal in marine invasive species, we identified genes in the DNA methylation and demethylation processes in the highly invasive model species, Ciona robusta, and subsequently investigated the expression patterns of these genes under recurring salinity stresses. After a genome-wide comprehensive survey, we found a total of six genes, including two genes of DNA methyltransferase 3a (DNMT3a1 and DNMT3a2), and one gene of DNA methyltransferase 1 (DNMT1), methyl-CpG-binding domain protein 2 (MBD2), methyl-CpG-binding domain protein 4 (MBD4) and ten-eleven-translocation protein 1 (TET1). Phylogenetic reconstruction and domain arrangement analyses showed that the deduced proteins of the identified genes were evolutionarily conserved and functionally similar with their orthologs. All genes were constitutively expressed in all four tested tissues. Interestingly, we found time-dependent and stress-specific gene expression patterns under high and low salinity stresses. Under the recurring high salinity stresses, DNMT3a1 and TET1 conformed to the definition of memory genes, while under the recurring low salinity stresses, two DNMT3a paralogues were identified as the memory genes. Altogether, our results clearly showed that the transcriptional patterns of (de)methylation-related genes were significantly influenced by environmental stresses, and the transcriptional memory of some (de)methylation-related genes should play crucial roles in DNA methylation-mediated stress memory during the process of biological invasions.

An Immune-Related Prognostic Classifier Is Associated with Diffuse Large B Cell Lymphoma Microenvironment.

BACKGROUND: Diffuse large B cell lymphoma (DLBCL) is a life-threatening malignant tumor characterized by heterogeneous clinical, phenotypic, and molecular manifestations. Given the association between immunity and tumors, identifying a suitable immune biomarker could improve DLBCL diagnosis. METHODS: We systematically searched for DLBCL gene expression microarray datasets from the GEO database. Immune-related genes (IRGs) were obtained from the ImmPort database, and 318 transcription factor (TF) targets in cancer were retrieved from the Cistrome Cancer database. An immune-related classifier for DLBCL prognosis was constructed using Cox regression and LASSO analysis. To assess differences in overall survival between the low- and high-risk groups, we analyzed the tumor microenvironment (TME) and immune infiltration in DLBCL using the ESTIMATE and CIBERSORT algorithms. WGCNA was applied to study the molecular mechanisms explaining the clinical significance of our immune-related classifier and TFs. RESULTS: Eighteen IRGs were selected to construct the classifier. The multi-IRG classifier showed powerful predictive ability. Patients with a high-risk score had poor survival. Based on the AUC for three- and five-year survival, the classifier exhibited better predictive power than clinical data. Discrepancies in overall survival between the low- and high-risk score groups might be explained by differences in immune infiltration, TME, and transcriptional regulation. CONCLUSIONS: Our study describes a novel prognostic IRG classifier with strong predictive power in DLBCL. Our findings provide valuable guidance for further analysis of DLBCL pathogenesis and clinical treatment.

LncRNA BCYRN1-induced autophagy enhances asparaginase resistance in extranodal NK/T-cell lymphoma.

Background: Asparaginase (ASP) is the cornerstone drug in the treatment of extranodal NK/T-cell lymphoma (ENKTCL), and the mechanisms of resistance to ASP remain largely unknown. Long non-coding RNAs play important roles in chemotherapy resistance in various cancers. However, the expression of BCYRN1 and its role in ENKTCL still remain unidentified. Methods: Lentivirus-mediated BCYRN1 overexpression and knockdown were performed in SNK-6 cells. Cell autophagy was analyzed by adenovirus expressing GFP-LC3B fusion protein. RNA pull-down and RNA Binding Protein Immunoprecipitation Assay were performed to investigate the relationship between BCYRN1 and p53. Western blot analysis was performed to assess the effect of BCYRN1 on different autophagy pathways. Finally, in vivo xenograft tumor model was constructed to analyze the effect of BCYRN1 on tumor growth and ASP resistance. Results: BCYRN1 was overexpressed in ENKTCL than normal NK cells, and patients with higher expression had significantly inferior progression-free survival (PFS). The IC50 value of ASP was significantly increased in BCYRN1-overexpressed SNK-6 cells and BCYRN1 overexpression could resist the inhibitory effect of ASP on proliferation. ASP could induce concurrent apoptosis and autophagy in ENKTCL, and the latter process was enhanced by overexpression of BCYRN1, mainly through affecting both PI3K/AKT/mTOR and p53/mTOR pathways. BCYRN1 could induce the degradation of p53 via ubiquitination, thus resulting in enhancement of autophagy and ASP resistance, which could be reversed by drug-induced autophagy inhibition. The effect of BCYRN1 on tumor growth and autophagy were confirmed in vivo xenograft model. Conclusions: It was found that BCYRN1 was a valuable prognostic biomarker in ENKTCL. BCYRN1 could promote resistance to ASP by inducing autophagy, which could be reversed by inhibition of autophagy. Our findings highlight the feasibility of combining autophagy inhibition and ASP in the treatment of ENKTCL.

[Effects of Arbuscular Mycorrhizal Fungi on the Growth of Reeds in Wetland Soils with Different Salt Content].

A greenhouse pot experiment was conducted to investigate the effects of arbuscular mycorrhizal (AM) fungi Claroideoglomus etunicatum (CE), Rhizophagus intraradices (RI), Funneliformis mosseae (FM) and Glomus versiforme (GV) on AM colonization rate, biomass, mineral nutrient uptake, C: N: P ratios and Na and Cl- concentrations of reeds (Phragmites australis) grown in saline and non-saline wetland soils. The aim was to provide a technical basis for the ecological revegetation and salinity restoration of wetland ecosystem. The results indicated that symbiotic associations were successfully established between the four isolates and reeds grown in the two types of wetland soils. The average AM colonization rates ranged from 2.5% to 38%. The mean root colonization rate of CE was significantly higher than those of the other three isolates. There were no significant differences in root colonization rates between saline and non-saline wetland soils. The biomass and nutrient contents of reeds grown in non-saline wetland soils were significantly higher than those grown in saline wetland soils. However, Na+ and Cl- concentrations of reeds grown in non-saline wetland soils were significantly lower than those grown in saline wetland soils. In non-saline wetland soils, inoculation with GV significantly increased the shoot dry weight and the shoot N, P, K, Ca and Mg contents of reeds. Inoculation with GV and RI significantly improved the root P and K contents of reeds. Inoculation with the four AM fungi significantly reduced the shoot N: P ratios. Inoculation with FM and GV significantly reduced the root C : N and C : P ratios. Inoculation with the four AM fungi significantly reduced the shoot Cl- concentrations. Inoculation with RI significantly reduced the shoot Na+ concentrations. In saline wetland soils, inoculation with AM fungi had no significant effect on the biomass, mineral nutrient uptake and Na+ and Cl- concentrations of reeds. The results demonstrated that the four AM fungi isolates had different effects on the growth of reeds in wetland soils with different salt contents. Inoculation with AM fungi played a more positive role in improving the growth of reeds in non-saline wetland soil than those in saline wetland soil. Further experiments should be conducted to screen optimal AM fungi isolates under field conditions and to evaluate the practical effects of AM fungi on the growth of reeds in wetland soils with different salt contents.

Contribution of arbuscular mycorrhizal fungi to the development of maize (Zea mays L.) grown in three types of coal mine spoils.

Coal mine spoils are usually unfavorable for plant growth and have different properties according to dumping years, weathering degree, and the occurrence of spontaneous combustion. The establishment of plant cover in mine spoils can be facilitated by arbuscular mycorrhizal fungi (AMF). A greenhouse pot experiment was conducted to evaluate the importance of AMF in plant adaptation to different mine spoils and the potential role of AMF for revegetation practices. We investigated the effects of Glomus aggregatum, Rhizophagus intraradices (syn. Glomus intraradices), and Funneliformis mosseae (syn. Glomus mosseae) on the growth, nutritional status, and metal uptake of maize (Zea mays L.) grown in recent discharged (S1), weathered (S2), and spontaneous combusted (S3) coal mine spoils. Symbiotic associations were successfully established between AMF and maize in three substrates. Mycorrhizal colonization effectively promoted plant growth by significantly increasing the uptake of nitrogen (N), phosphorus (P), and potassium (K), adjusting C:N:P stoichiometry and alleviating toxic effects of heavy metals. G. aggregatum, R. intraradices, and F. mosseae exhibited different mycorrhizal effects in response to mine spoil types. F. mosseae was the most effective in the development of maize in S1 and may be the most appropriate for revegetation of this substrate, while R. intraradices played the most beneficial role in S2 and S3. Our results suggest that inoculation with AMF can enhance plant adaptation to different types of coal mine spoils and play a positive role in the revegetation of coal mine spoil banks.

[Characteristic and evaluation of soil pollution by heavy metal in different functional zones of Hohhot].

The residential areas, cultural and educational areas, city parks, commercial areas, urban roads, industrial zones, and development zones in Hohhot were selected as the research objects. Sixty-two soil samples were collected by triple subsampling technique in the seven functional zones. The aim of this study is to control the soil heavy metal pollution of Hohhot and provide the basic information. To investigate and analyze the heavy metal pollution in soil in different functional zones of Hohhot, the pollution of heavy metal was assessed with single factor pollution index and Nemerow integrated pollution index, and the pollution sources were discriminated by Principal Component Analysis. Contents of seven kinds of heavy metals were analyzed in different functional zones of Hohhot. The mean contents of heavy metals in soil samples exceeded the corresponding background values in the Inner Mongolia Autonomous Region. The mean contents of Cu and Zn were 2. 33 and 1. 85 times, respectively, as high as the soil background values of the Inner Mongolia Autonomous Region. Single factor pollution index showed that the urban soil in Hohhot has been polluted by heavy metals. The Cu pollution was the most severe in commercial areas, and the pollution degree was in the following order: Cu > Zn > Cr > Mn > As > Ni > Pb. Nemerow integrated pollution index showed that soils from the commercial areas were seriously contaminated by heavy metals. The soil of urban roads was moderately polluted. The soils from cultural and educational areas and the city parks were slightly polluted. The Nemerow integrated pollution index of the seven areas ranked as follows: commercial areas (3.03) > urban roads (2.12) > residential areas (1.98) > cultural and educational areas (1.81) > industrial zones (1.72) > development zones (1.36) > city parks (1. 28). The results of Principal Component Analysis showed that the heavy metals in soil of Hohhot came from different sources. Cr, Cu, Mn, Pb and Zn were mainly originated from anthropogenic sources while Ni and As were mainly controlled by natural sources. The healthy development of urban ecosystem has been threatened by soil heavy metal pollution in Hohhot.

[Distribution characteristic and current situation of soil rare earth contamination in the Bayan Obo mining area and Baotou tailing reservoir in Inner Mongolia].

The pollution status and distribution characteristic of rare earth elements in soil were analyzed around Bayan Obo mining area and Baotou tailing reservoir located in Inner Mongolia grassland ecosystem, aiming at grasping the overall situation of grassland ecosystem pollution caused by rare earth elements and providing basic information as well as theoretical basis. The results indicated that seven rare earth elements in soils from different directions of Baotou tailing reservoir accumulated to a certain extent compared to the soil background value of Inner Mongolia. The pollution degree was Ce > La > Nd > Pr > Sm > Y > Eu. Within 50 m from the edge of tailing reservoir, soil rare earth contamination was the most serious, with the concentrations of La, Ce, Pr, Nd, Sm, Eu and Y reaching 11,45.0 mg x kg(-1), 23,636.0 mg x kg(-1), 4568.16 mg x kg(-1) , 6855.51 mg x kg(-1), 582.18 mg x kg(-1), 94.21 mg x kg(-1)), and 136.25 mg x kg(-1), respectively. Owing to the dominant wind direction of northwest, soils from the southeast were contaminated most seriously. For Bayan Obo mining area, the concentrations of seven rare earth elements in soil from the mining area were significantly higher than those of other areas investigated, with the concentrations of La, Ce, Pr, Nd, Sm, Eu and Y reaching 3112.56 mg x kg(-1), 7142.12 mg x kg(-1), 1467.12 mg x kg(-1), 2552.80 mg x kg(-1), 210.80 mg x kg(-1), 36.20 mg x kg(-1) and 63.22 mg x kg(-1), respectively. The soils of six areas of Bayan Obo mining area were all contaminated by rare earth elements, and the contamination degree was in the order of mining area > outside the dump > east side of the railway > the dump > outside the urban area > west side of the railway. Besides, the transportation of rare earth ore led to the soil rare earth contamination along the railway, and the distribution characteristic of rare earth elements in soils along the railway was affected by the dominant wind direction of northwest. Baotou tailing reservoir and Bayan Obo mining area had the same contamination characteristic, and the concentrations of rare earth elements were in accordance with those in the tailings. The health and stabilization of local grassland ecosystem are being threatened by excessive soil rare earth elements.

[Effects of arbuscular mycorrhizal fungi on the growth and rare earth elements uptake of soybean grown in rare earth mine tailings].

A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare earth elements by soybean (Glycine max) grown in rare earth mine tailings. The aim was to provide a basis for the revegetation of rare earth mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare earth tailings and play a positive role in revegetation of rare earth mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.