Flooding drives the temporal turnover of antibiotic resistance gene in manure-amended soil-water continuum.

Rice paddy soil is a hotspot of antibiotic resistance genes (ARGs) due to the application of organic fertilizers. However, the temporal dynamics of ARGs in rice paddy soil and its flooded water during the growing season remain underexplored. In this study, a microcosm experiment was conducted to explore the ARG profiles in a long term (130 days) flooded two-phase manure-amended soil-water system. By using high-throughput quantitative PCR array, a total of 23-98 and 34-85 ARGs were detected in the soil and overlying water, respectively. Regression analysis exhibited significant negative correlations between ARG profile similarities and flooding duration, indicating that flooding significantly altered the resistome (P < 0.001). This finding was validated by the increased ARG abundance in the soil and the overlying water, for example, after 130 days flooding, the abundance of ARGs in CK soil was increased from 0.03 to 1.20 copies per 16S rRNA. The PCoA analysis further suggested pig manure application resulted in distinct ARG profiles in the soil-water continuum compared with those of the non-amended control (Adonis, P < 0.05). The Venn diagram showed that all ARGs detected in the pig manure were present in the treated soil. Twelve ARGs (e.g., sul1) were shared among the pig manure, manure-amended soil, and overlying water, indicating that certain manure- or soil-borne ARGs were readily dispersed from the soil to the overlying water. Moreover, the enhanced relationships between the ARGs and mobile genetic elements in pig manure applied soil-water continuum indicate that the application of organic matter could accelerate the emergence and dissemination of ARGs. These findings suggested that flooding represents a crucial pathway for dispersal of ARGs from the soil to the overlying water. Identification of highly mobile ARGs in the soil-water continuum is essential for assessing their potential risk to human health and promoting the development of sustainable agricultural practices to mitigate their spread.

Lactiplantibacillus plantarum Regulated Intestinal Microbial Community and Cytokines to Inhibit Salmonella typhimurium Infection.

Lactic acid bacteria (LAB) are recognized as food-grade safe microorganisms and have many beneficial effects. LAB could maintain the host intestinal homeostasis and regulate intestinal microbial community to exert antibacterial effects. In this study, Lactiplantibacillus plantarum (L. plantarum, Lp01) strain isolated from pig intestine was orally administered to C57BL/6 mice, and mice were then infected with Salmonella typhimurium (ATCC14028). The protective effects of L. plantarum were evaluated by monitoring body weight loss, survival rates, bacterial loads in tissue, colon histopathology analysis, and cytokine secretion. 16S rRNA gene sequencing was also utilized to detect the dynamics of the blind gut microbial community in mice. We found that L. plantarum could significantly reduce the body weight loss and improve the survival rates. The survival rate in the L. P-Sty group was up to 67.5%, which was much higher than that in the STY group (25%). Counting of bacterial loads displayed that the colony-forming unit (CFU) of S. typhimurium in the spleen (p < 0.05) and the liver (p < 0.05) from L. P-Sty group both decreased, compared with STY group. Intestinal histopathology showed that it alleviated the intestinal injury caused by Salmonella, inhibited the secretion of pro-inflammatory cytokines, and promoted anti-inflammatory cytokines (p < 0. 01). In addition, L. plantarum also significantly ameliorated the intestinal gut microbiome disturbance caused by Salmonella. It displayed an obvious increase of beneficial bacteria including Lactobacillus and Bacteroidetes and reduction of pathogenic bacteria like Proteobacteria. In conclusion, L. plantarum could regulate microbial community to inhibit Salmonella typhimurium infection.

Aridity differentially alters the stability of soil bacterial and fungal networks in coastal and inland areas of Australia.

Despite the importance of soil bacterial and fungal communities for ecosystem services and human welfare, how their ecological networks respond to climatic aridity have yet been evaluated. Here, we collected soil samples from 47 sites across 2500 km in coastal and inland areas of eastern Australia with contrasting status of aridity. We found that the diversity of both bacteria and fungi significantly differed between inland and coastal soils. Despite the significant differences in soil nutrient availability and stoichiometry between the inland and coastal regions, aridity was the most important predictor of bacterial and fungal community compositions. Aridity has altered the potential microbial migration rates and further impacted the microbial assembly processes by increasing the importance of stochasticity in bacterial and fungal communities. More importantly, ecological network analysis indicated that aridity enhanced the complexity and stability of the bacterial network but reduced that of the fungal network, possibly due to the contrasting impacts of aridity on the community-level habitat niche breadth and overlaps. Our work paves the way towards a more comprehensive understanding of how climate changes will alter soil microbial communities, which is integral to predicting their long-term consequences for ecosystem sustainability and resilience to future disturbances.

Effects of soil protists on the antibiotic resistome under long term fertilization.

Soil protists are key in regulating soil microbial communities. However, our understanding on the role of soil protists in shaping antibiotic resistome is limited. Here, we considered the diversity and composition of bacteria, fungi and protists in arable soils collected from a long-term field experiment with multiple fertilization treatments. We explored the effects of soil protists on antibiotic resistome using high-throughput qPCR. Our results showed that long term fertilization had stronger effect on the composition of protists than those of bacteria and fungi. The detected number and relative abundance of antibiotic resistance genes (ARGs) were elevated in soils amended with organic fertilizer. Co-occurrence network analysis revealed that changes in protists may contribute to the changes in ARGs composition, and the application of different fertilizers altered the communities of protistan consumers, suggesting that effects of protistan communities on ARGs might be altered by the top-down impact on bacterial composition. This study demonstrates soil protists as promising agents in monitoring and regulating ecological risk of antibiotic resistome associated with organic fertilizers.

Co-effect of cadmium and iron oxide nanoparticles on plasmid-mediated conjugative transfer of antibiotic resistance genes.

Conjunctive transfer of antibiotic resistance genes (ARGs) among bacteria driven by plasmids facilitated the evolution and spread of antibiotic resistance. Heavy metal exposure accelerated the plasmid-mediated conjunctive transfer of ARGs. Nanomaterials are well-known adsorbents for heavy metals removal, with the capability of combatting resistant bacteria/facilitating conjunctive transfer of ARGs. However, co-effect of heavy metals and nanomaterials on plasmid-mediated conjunctive transfer of ARGs was still unknown. In this study, we investigated the effect of the simultaneous exposure of Cd2+ and nano Fe2O3 on conjugative transfer of plasmid RP4 from Pseudomonas putida KT2442 to water microbial community. The permeability of bacterial cell membranes, antioxidant enzyme activities and conjugation gene expression were also investigated. The results suggested that the combination of Cd2+ and high concentration nano Fe2O3 (10 mg/L and 100 mg/L) significantly increased conjugative transfer frequencies of RP4 plasmid (p < 0.05). The most transconjugants were detected in the treatment of co-exposure to Cd2+ and nano Fe2O3, the majority of which were identified to be human pathogens. The mechanisms of the exacerbated conjugative transfer of ARGs were involved in the enhancement of cell membrane permeability, antioxidant enzyme activities, and mRNA expression levels of the conjugation genes by the co-effect of Cd2+ and nano Fe2O3. This study confirmed that the simultaneous exposure to Cd2+and nano Fe2O3 exerted a synergetic co-effect on plasmid-mediated conjunctive transfer of ARGs, emphasizing that the co-effect of nanomaterials and heavy metals should be prudently evaluated when combating antibiotic resistance.

Sorghum rhizosphere effects reduced soil bacterial diversity by recruiting specific bacterial species under low nitrogen stress.

Rhizosphere microbiota play a pivotal role in promoting plant growth and defending against pathogens, but their responses to abiotic environmental stress remain largely elusive. Here, we investigated the influences of low-N stress on rhizosphere bacteria of six sorghum cultivars in a glasshouse experiment. The alpha diversity of bacteria (as revealed by Shannon diversity and Chao1 richness indices) was remarkably lower in rhizosphere soils than in bulk soils, and was significantly higher under low-N stress than under N addition. Principal coordinates analysis revealed that the bacterial community compositions in rhizosphere soils were clearly separated from bulk soils, and the rhizosphere soils under low-N stress or with N fertilization were clearly separated, indicating that both rhizosphere effects and N fertilization impacted the rhizosphere bacterial community. Notably, the relative abundances of beneficial bacteria such as Bacillaceae and Streptomycetaceae significantly increased in rhizosphere soils under low-N stress, which had significantly positive correlations with the sorghum N uptake. The relative abundance of Nitrosomonadaceae in rhizosphere soils was significantly lower than that in bulk soils, while the relative abundance of Rhizobiaceae showed an opposite pattern. Taken together, our results suggested that sorghum rhizosphere effects can reduce soil bacterial diversity possibly through recruiting specific bacterial species under low N stress.

Advances in Research on Anticancer Properties of Salidroside.

Salidroside is a phenolic secondary metabolite present in plants of the genus Rhodiola, and studies investigating its extensive pharmacological activities and mechanisms have recently attracted increasing attention. This review summarizes the progress of recent research on the antiproliferative activities of salidroside and its effects on breast, ovarian, cervical, colorectal, lung, liver, gastric, bladder, renal, and skin cancer as well as gliomas and fibrosarcomas. Thus, it provides a reference for the further development and utilization of salidroside.

Subtotal gastrectomy combined with chemotherapy: An effective therapy for patients with circumscribed Borrmann type IV gastric cancer.

BACKGROUND: Although Borrmann type IV (B-4) gastric cancer has a higher mortality rate and presents distant metastasis easily, especially peritoneal metastasis, when diagnosed, some B-4 patients were found to have no distant metastasis by preoperative detection and underwent curative surgery, which was defined as circumscribed B-4 in our study. In this study, we focused on the circumscribed B-4 patients without distant metastasis during surgery to identify factors related to prognosis and postoperative peritoneal cavity metastasis (PPCM), which is important for selecting an appropriate therapeutic strategy. AIM: To identify factors related to the prognosis and PPCM of B-4 patients. METHODS: A total of 117 B-4 patients who underwent gastrectomy between January 2005 and December 2012 were included in this study. Survival analysis was performed using Kaplan-Meier analysis and Cox multivariate models. Pearson correlation analyses were performed to identify the factors related to PPCM. All statistical analyses were performed using SPSS 20.0. RESULTS: Lymph node status, gastrectomy type, and postoperative chemotherapy were independent prognostic factors in 117 circumscribed B-4 patients. Subtotal gastrectomy combined with chemotherapy could significantly improve the long-term survival time. Six patients who were diagnosed with pN0 and received the combination therapy had a 3-year survival rate of 100% and a median survival of 77.7 mo. Even for patients with metastatic lymph nodes (n = 13), the combination therapy also increased the 3-year overall survival rate to 57.1%. In addition, positive lymph node status was the only factor (P = 0.005) correlated with PPCM in certain B-4 patients, and chemotherapy was useful for suppressing PPCM in patients with subtotal gastrectomy but not in those with total gastrectomy. CONCLUSION: Lymph node status is an independent prognostic factor for circumscribed B-4 patients. In addition, subtotal gastrectomy and postoperative chemotherapy could effectively improve prognosis and even suppress PPCM.

Inhibitory effects of salidroside on MCF-7 breast cancer cells in vivo.

OBJECTIVE: We investigated the antitumor effects of salidroside and preliminarily examined its underlying mechanisms by establishing a nude mouse model bearing MCF-7 breast cancer cell xenografts. METHODS: The mice were grouped and intraperitoneally injected with salidroside, paclitaxel, or physiological saline. Tumor samples were weighed, and immunohistochemical staining with hematoxylin and eosin and anti-CD34 antibody was performed. Tumor cell apoptosis was observed using the terminal deoxynucleotidyl transferase deoxyuridine dUTP nick end labeling assay. Bcl-1, p53, Bax, and caspase 3 expression in tumor tissues was determined via western blotting. RESULTS: The tumor inhibition rate of high-dose salidroside was 75.16%, which was significantly higher than the rates for paclitaxel and saline. A tumor tissue pathology analysis revealed that high-dose salidroside inhibited tumor cell proliferation and promoted tumor cell apoptosis. Western blotting revealed that Bcl-2 and p53 expression were significantly lower in the salidroside group than in the other groups, whereas Bax and caspase 3 (17 kDa) expression were increased. CONCLUSIONS: Salidroside was more effective than paclitaxel in inhibiting tumor growth in MCF-7 breast cancer cell-bearing nude mice. The mechanism of action may involve Bcl-2 and p53 downregulation and Bax and caspase 3 upregulation, thereby increasing proapoptotic factor expression and inducing tumor cell apoptosis.

Prognostic significance of 14v-lymph node dissection to D2 dissection for lower-third gastric cancer.

BACKGROUND: Radical gastrectomy with D2 lymph node (LN) dissection is the standard surgical procedure for patients with resectable gastric cancer (GC). In the fifteenth edition of the Japanese Classification of Gastric Carcinoma, the 14v LN (LNs along the root of the superior mesenteric vein) was defined as the regional gastric LN. The efficacy of 14v LN dissection during radical distal gastrectomy for lower-third GC remains controversial. AIM: To analyze whether the addition of 14v LN dissection improved the survival of patients with lower-third GC. METHODS: The data from 65 patients who underwent 14v LN dissection and 65 patients treated without 14v LN dissection were selected using the propensity score-matched method from our institute database constructed between 2000 and 2012. Overall survival was compared between the groups. RESULTS: Overall survival was similar between patients with 14v LN metastasis and those with distant metastasis (P = 0.521). Among patients with pathological stage IIIA disease, those who were treated with 14v LN dissection had a significantly higher overall survival than those treated without it (P = 0.020). Multivariate analysis showed that age < 65 years and pT2-3 stage were independent favorable prognostic factors for prolonged overall survival in patients with pathological stage IIIA disease. Patients with No. 1, No. 6, No. 8a, or No. 11p LN metastasis were at higher risk of having 14v LN metastasis. CONCLUSION: Adding 14v LN dissection to D2 dissection during radical distal gastrectomy may improve the overall survival of patients with pathological stage IIIA lower-third GC.

Effects of biochar amendments on antibiotic resistome of the soil and collembolan gut.

A diverse array of ARGs has been detected in the guts of soil fauna residing in farmland soil. Biochar has been widely used in farmland for soil remediation and improvement of soil quality; however, the effects of biochar amendment on the gut-associated ARGs of soil fauna remain unclear. In the present study, collembolans were cultivated in soils amended with 6 types of biochars. High-throughput qPCR was used to establish ARG profiles of the collembolan guts as well as the surrounding soils. A total of 73 and 162 subtypes of ARGs were detected in the collembolan guts and soils, respectively. Biochar amendment significantly altered the ARG compositions of the collembolan guts and soils, in a biochar quality-dependent manner. However, only manure-derived biochar, which contained elevated concentrations of heavy metals, increased the relative abundance of gut-associated ARGs. Changes in the gut microbial community, MGEs and biochar properties explained 84% of the total ARG variations in the collembolan guts. The findings of this study suggested that biochar properties should receive more attention, as high doses of heavy metals in biochar could increase the abundance of ARGs in collembolan guts, thereby contributing to the spread of ARGs in the environment through collembolan movement.

Mobile Incubator for Iron(III) Reduction in the Gut of the Soil-Feeding Earthworm Pheretima guillelmi and Interaction with Denitrification.

Diets of soil-feeding earthworms contain abundant nitrate and iron(III) oxides, which are potential electron acceptors for mineralization of organic compounds. The earthworm gut provides an ideal habitat for ingested iron(III)-reducing microorganisms. However, little is known about iron(III) reduction and its interaction with other processes in the guts of earthworms. Here, we determined the dynamics of iron(III) and revealed its interaction with the turnover of organic acids and nitrate in the gut of the earthworm Pheretima guillelmi. Samples from gut contents combined with anoxic incubation were used for chemical analysis and 16S rRNA based Illumina sequencing. Chemical analysis showed that higher ratios of iron(II)/iron(III), nitrite/nitrate, and more abundant organic acids were contained in the in vivo gut of the earthworm P. guillelmi than those in the in situ soil. A higher rate of iron(III) reduction was detected in treatments of microcosmic incubation with gut contents (IG gut) than that with soil (IG soil), and nitrate reduction occurred earlier than iron(III) reduction in both treatments. Potential iron(III) reducers were dominated by fermentative genera Clostridium, Bacillus, and Desulfotomaculum in the treatment of IG gut, while they were dominated by dissimilatory iron(III)-reducing genera Geobacter in the treatment of IG soil. The iron(III)-reducing microbial community shared several genera with denitrifers in the treatment of IG gut, revealing a close link between iron(III) reduction and denitrification in the gut of earthworms. Collectively, our findings demonstrated that iron(III) reduction occurred along the gut and provided novel insights into the great contribution of earthworm gut microbiota on Fe and the associated C and N cycling in soil environments.

Association of IL-8 gene promoter -251 A/T and IL-18 gene promoter -137 G/C polymorphisms with head and neck cancer risk: a comprehensive meta-analysis.

PURPOSE: No consensus exists on the impact of polymorphisms in cytokines (such as interleukin IL-8 and IL-18) on cancer risk; moreover, there is very little evidence regarding head and neck cancer (HNC). METHODS: Thus, a meta-analysis including 22 studies with 4731 cases and 8736 controls was conducted to evaluate this association. The summary odds ratio (OR) and corresponding 95% confidence intervals (CIs) for C-X-C motif chemokine ligand 8 (CXCL8, which encodes IL-8) and IL-18 polymorphisms and HNC risk were estimated. RESULTS: The results showed a significantly increased risk of HNC susceptibility for IL18 -137 G/C in five genetic models, but, interestingly, no significant association was found for the CXCL8 -251 A/T polymorphism. When stratified by cancer type, an increased risk of nasopharyngeal cancer was found for both -137 G/C and -251A/T. When the studies were stratified by ethnicity and genotyping method, there were significant associations between Asian populations and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) studies for -137 G/C, and African populations for -251 A/T in some genetic models. A positive association was also found between the population-based groups in some models for -137 G/C; conversely, significantly decreased risk was found among the -251 A/T hospital-based group. Meta-regression was also conducted. The publication year, control source, and cancer type contributed to CXCL8 -251 A/T heterogeneity; however, no factors were found that contributed to IL-18 -137 G/C heterogeneity. Marginal significance was found in the recessive model for IL-18 -137 G/C by Egger's test, whereas no publication bias was detected for CXCL8 -251 A/T. CONCLUSIONS: The results indicate that the IL-18 -137 G/C polymorphism is associated with HNC risk, especially nasopharyngeal cancer, in Asian populations and, when using PCR-RFLP, CXCL8 -251 A/T polymorphisms play a complex role in HNC development.

Downregulation and DNA methylation of ECRG4 in gastric cancer.

BACKGROUND: Esophageal cancer-related gene 4 (ECRG4) is a novel candidate tumor suppressor gene. Our study investigated the expression and function of ECRG4 in gastric cancer and highlighted the role of DNA hypermethylation at the promoter in silencing the ECRG4 expression. METHODS: The GSE63089 data set was obtained from the Gene Expression Omnibus and analyzed for differentially expressed genes. Carcinoma and para-carcinoma tissues of 102 patients with gastric cancer were collected from January 2010 to July 2011. Immunohistochemistry, real-time polymerase chain reaction (PCR), and western blot analyses were performed to evaluate the expression of ECRG4. After measuring the change in the level of ECRG4 expression, CCK-8, Transwell, and flow cytometric cell cycle assays were performed. In addition, methylation-specific PCR was performed to detect the methylation state of ECRG4, and 5-aza-2'-deoxycytidine was used for demethylation of ECRG4. All statistical analyses were performed using the SPSS 17.0 software. RESULTS: We found that ECRG4 expression was downregulated in gastric cancer, and this was closely related to lymph node metastasis. After ECRG4 was silenced using a specific small interfering RNA, the BGC-823 cell line became highly aggressive and proliferative. In addition, we verified whether downregulation of ECRG4 was highly correlated with DNA methylation of the ECRG4 promoter and found that the demethylating agent 5-aza-2'-deoxycytidine could effectively enhance ECRG4 expression. CONCLUSION: The aberrant expression of ECRG4 is associated with hypermethylation in the promoter region and plays an important role in the malignancy of gastric cancer. Therefore, ECRG4 may be a potential biomarker for molecular diagnosis of gastric cancer, and the use of 5-Aza-dC to reverse the hypermethylation of ECRG4 may be a new approach to the treatment of gastric cancer.