15N-DNA stable isotope probing reveals niche differentiation of ammonia oxidizers in paddy soils.

Chemoautotrophic canonical ammonia oxidizers (ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB)) and complete ammonia oxidizers (comammox Nitrospira) are accountable for ammonia oxidation, which is a fundamental process of nitrification in terrestrial ecosystems. However, the relationship between autotrophic nitrification and the active nitrifying populations during 15N-urea incubation has not been totally clarified. The 15N-labeled DNA stable isotope probing (DNA-SIP) technique was utilized in order to study the response from the soil nitrification process and the active nitrifying populations, in both acidic and neutral paddy soils, to the application of urea. The presence of C2H2 almost completely inhibited NO3--N production, indicating that autotrophic ammonia oxidation was dominant in both paddy soils. 15N-DNA-SIP technology could effectively distinguish active nitrifying populations in both soils. The active ammonia oxidation groups in both soils were significantly different, AOA (NS (Nitrososphaerales)-Alpha, NS-Gamma, NS-Beta, NS-Delta, NS-Zeta and NT (Ca. Nitrosotaleales)-Alpha), and AOB (Nitrosospira) were functionally active in the acidic paddy soil, whereas comammox Nitrospira clade A and Nitrosospira AOB were functionally active in the neutral paddy soil. This study highlights the effective discriminative effect of 15N-DNA-SIP and niche differentiation of nitrifying populations in these paddy soils. KEY POINTS: • 15N-DNA-SIP technology could effectively distinguish active ammonia oxidizers. • Comammox Nitrospira clade A plays a lesser role than canonical ammonia oxidizers. • The active groups in the acidic and neutral paddy soils were significantly different.

DNA-SIP delineates unique microbial communities in the rhizosphere of the hyperaccumulator Sedum alfredii which are beneficial to Cd phytoextraction.

Rhizo-microbe recruited by hyperaccumulating plants are crucial for the extraction of metals from contaminated soils. It is important, but difficult, to identify the specific rhizosphere microbes of hyperaccumulators shaped by root exudation. Continuous 13CO2 labeling, microbial DNA-based stable isotope probing (DNA-SIP), and high throughput sequencing were applied to identify those rhizosphere microorganisms using exudates from the Cd hyperaccumulator Sedum alfredii. In contrast to its non-hyperaccumulating ecotype (NAE), the hyperaccumulating ecotype (HAE) of S. alfredii strongly changed the rhizosphere environment and extracted a 5-fold higher concentration of Cd from contaminated soil. Although both HAE and NAE harbored Streptomyces, Massilia, Bacillus, and WPS-2 Uncultured Bacteria with relative abundance of more than 1% in the rhizosphere associated with plant growth and immunity, the HAE rhizosphere specifically recruited Rhodanobacter (2.66%), Nocardioides (1.16%), and Burkholderia (1.01%) through exudates to benefit the extraction of Cd from soil. Different from the bacterial network with weak cooperation in the NAE rhizosphere, a closed-loop bacterial network shaped by exudates was established in the HAE rhizosphere to synergistically resist Cd. This research reveals a specific rhizosphere bacterial community induced by exudates assisted in the extraction of Cd by S. alfredii and provides a new perspective for plant regulation of the rhizo-microbe community beneficial for optimizing phytoremediation.

Comparing the variations and influencing factors of CH4 emissions from paddies and wetlands under CO2 enrichment: A data synthesis in the last three decades.

Understanding and quantifying the impact of elevated tropospheric carbon dioxide concentration (e [CO2]) on methane (CH4) globally is important for effectively assessing and mitigating climate warming. Paddies and wetlands are the two important sources of CH4 emissions. Yet, a quantitative synthetic investigation of the effects of e [CO2] on CH4 emissions from paddies and wetlands on a global scale has not been conducted. Here, we conducted a meta-analysis of 488 observation cases from 40 studies to assess the long-term effects of e [CO2] (ambient [CO2]+ 53-400 µmol mol-1) on CH4 emissions and to identify the relevant key drivers. On aggregate, e [CO2] increased CH4 emissions by 25.7% (p < 0.05) from paddies but did not affect CH4 emissions from wetlands (-3.29%; p > 0.05). The e [CO2] effects on paddy CH4 emissions were positively related to that on belowground biomass and soil-dissolved CH4 content. However, these factors under e [CO2] resulted in no significant change in CH4 emissions in wetlands. Particularly, the e [CO2]-induced abundance of methanogens increased in paddies but decreased in wetlands. In addition, tillering number of rice and water table levels affected e [CO2]-induced CH4 emissions in paddies and wetlands, respectively. On a global scale, CH4 emissions changed from an increase (+0.13 and + 0.86 Pg CO2-eq yr-1) under short-term e [CO2] into a decrease and no changes (-0.22 and + 0.03 Pg CO2-eq yr-1) under long-term e [CO2] in paddies and wetlands, respectively. This suggested that e [CO2]-induced CH4 emissions from paddies and wetlands changed over time. Our results not only shed light on the different stimulative responses of CH4 emissions to e [CO2] from paddy and wetland ecosystems but also suggest that estimates of e [CO2]-induced CH4 emissions from global paddies and wetlands need to account for long-term changes in various regions.

Applying struvite as a N-fertilizer to mitigate N2O emissions in agriculture: Feasibility and mechanism.

Nitrous oxide (N2O) is an effective ozone-depleting substance and an important greenhouse gas in the atmosphere. Fertilization is a major factor that dictates agricultural N2O emissions. In this work, as opposed to the commonly-seen highly-soluble nitrogen (N) fertilizers, the feasibility of using struvite as a slow-releasing N-fertilizer and its mechanism for mitigating N2O emissions were investigated. During the 149-d field cultivation of water spinach (Ipomoea Aquatica Forsk), struvite exhibited comparable crop yields, with a 40.8-58.1% N2O reduction compared with commercial fertilizers. In addition, struvite fertilization increased soil bacterial diversity and denitrification genes levels (narG, nirS, nirK, norB and nosZ) effectively, but decreased nitrification genes contents (amoA). By conducting partial least-square path modeling, it was found that the use of struvite would satisfy the soil N control and pH regulation, which altered N-cycling related bacteria and ultimately mitigated N2O emissions. From an economic aspect, using struvite as a N-fertilizer may increase the struvite market price from 50 to 131.7 €/ton. These findings help change the inherent impression that struvite is only suitable as a P-fertilizer, the application of struvite as N-fertilizer could effectively mitigate the agriculture N2O emission and inspire the application of struvite-based P-recovery technologies.

Indicator species drive the key ecological functions of microbiota in a river impacted by acid mine drainage generated by rare earth elements mining in South China.

Acid mine drainage (AMD) generated by rare earth elements (REEs) deposits exploration contains high concentrations of REEs, ammonium and sulfates, which is quite different from typical metallic AMD. Currently, microbial responses and ecological functions in REEs-AMD impacted rivers are unknown. Here, 16S rRNA analysis and genome-resolved metagenomics were performed on microbial community collected from a REEs-AMD contaminated river. The results showed that REEs-AMD significantly changed river microbial diversity and shaped unique indicator species (e.g. Thaumarchaeota, Methylophilales, Rhodospirillales and Burkholderiales). The main environmental factors regulating community were pH, ammonium and REEs, among which high concentration of REEs increased REEs-dependent enzyme-encoding genes (XoxF and ExaF/PedH). Additionally, we reconstructed 566 metagenome-assembled genomes covering 70.4% of identifying indicators. Genome-centric analysis revealed that the abundant archaea Thaumarchaeota and Xanthomonadaceae were often involved in nitrification and denitrification, while family Burkholderiaceae were capable of sulfide oxidation coupled with dissimilatory nitrate reduction to ammonium. These indicators play crucial roles in nitrogen and sulfur cycling as well as REEs immobilization in REEs-AMD contaminated rivers. This study confirmed the potential dual effect of REEs on microbial community at the functional gene level. Our investigation on the ecological roles of indicators further provided new insights for the development of REEs-AMD bioremediation.

Metallopolymer Particle Engineering via Etching of Boronate Polymers toward High-Performance Overall Water Splitting Catalysts.

Metallopolymers combine the property features of both metallic compounds and organic polymers, representing a typical direction for the design of high-performance hybrid materials. Here, a highly adaptive etching method to create pores and cavities in the metallopolymer particles is established. Starting from boronate polymer (BP) and inorganic@BP core-shell particles, porous, hollow, and yolk-shell metallopolymer particles can be fabricated, respectively. By taking advantage of the easy control over composition and pore/cavity structure, these metallopolymer particles provide a universal platform for the fabrication of nitrogen, boron co-doped carbon nanocomposites loaded with metals (M-NBCs). The as-prepared M-NBCs exhibit remarkable catalytic activities toward oxygen evolution reaction and hydrogen evolution reaction. An alkaline overall water splitting cell assembled by using M-NBCs as the anode and cathode can be driven by a single AAA battery. The proposed strategy for the construction of metallopolymer composites may enlighten for the design of complex hybrid nanomaterials.

Short-Term Benzalkonium Chloride (C12) Exposure Induced the Occurrence of Wide-Spectrum Antibiotic Resistance in Agricultural Soils.

Antibiotic resistance genes (ARGs) are global pollutants that pose a potential risk to human health. Benzalkonium chloride (C12) (BC) disinfectants are thought to exert selection pressure on antibiotic resistance. However, evidence of BC-induced changes in antibiotic resistance in the soil environment is lacking. Here, we established short-term soil microcosms to investigate ARG profile dynamics in agricultural soils amended with sulfamethazine (SMZ, 10 mg kg-1) and gradient concentrations of BC (0-100 mg kg-1), using high-throughput quantitative PCR and Illumina sequencing. With the increase in BC concentration, the number of ARGs detected in the soil increased, but the normalized ARG abundance decreased. The added SMZ had a limited impact on ARG profiles. Compared to broad-spectrum fungicidal BC, the specificity of SMZ significantly affected the microbial community. Network analysis found that low-medium BC exposure concentrations resulted in the formation of small but strong ARG co-occurrence clusters in the soil, while high BC exposure concentration led to a higher incidence of ARGs. Variation partitioning analysis suggested that BC stress was the major driver shaping the ARG profile. Overall, this study highlighted the emergence and spread of BC-induced ARGs, potentially leading to the antimicrobial resistance problem in agricultural soils.

Interactive effects of microplastics, biochar, and earthworms on CO2 and N2O emissions and microbial functional genes in vegetable-growing soil.

Soil carbon dioxide (CO2) and nitrous oxide (N2O) emissions are two main greenhouse gases that play important roles in global warming. Studies have shown that microplastics, biochar, and earthworms can significantly affect soil greenhouse gas emissions. However, few studies have explored how their interactions affect soil CO2 and N2O emissions. A mesocosm experiment was conducted to investigate their interactive effects on soil greenhouse gases and soil microbial functional genes in vegetable-growing soil under different incubation times. Biochar alone or combined with microplastics significantly decreased soil CO2 emissions but had no effect on soil N2O emissions. Microplastics and biochar inhibited CO2 emissions and promoted N2O emissions in the soil with earthworms. The addition of microplastics, biochar, and earthworms had significant effects on soil chemical properties, including dissolved organic carbon, ammonia nitrogen, nitrate nitrogen, total nitrogen, and pH. Microplastics and earthworms selectively influenced microbial abundances and led to a fungi-prevalent soil microbial community, while biochar led to a bacteria-prevalent microbial community. The interactions of microplastics, biochar, and earthworms could alleviate the reduction of the bacteria-to-fungi ratio and the abundance of microbial functional genes caused by microplastics and earthworms alone. Microplastics significantly inhibited microorganisms as well as C and N cycling functional genes in earthworm guts, while biochar obviously stimulated them. The influence of the addition of exogenous material on soil greenhouse gas emissions, soil chemical properties, and functional microbes differed markedly with soil incubation time. Our results indicated that biochar is a promising amendment for soil with microplastics or earthworms to simultaneously mitigate CO2 emissions and regulate soil microbial community composition and function. These findings contribute to a better understanding of the interaction effects of microplastics, biochar, and earthworms on soil carbon and nitrogen cycles, which could be used to help conduct sustainable environmental management of soil.

Beneficial Effects of Oleosomes Fused with Human Fibroblast Growth Factor 1 on Wound Healing via the Promotion of Angiogenesis.

In our previous study, human fibroblast growth factor 1 was successfully fused with oleosomes, energy-storing organelles of seeds, which are considered to be excellent "expression carriers" for substances with a convenient purification process. The present work aimed to explore the beneficial effects of oleosomes fused with human fibroblast growth factor 1 (OLAF) on wound healing. The data showed marked improvements in terms of the angiogenesis, vascular integrity, collagen and inflammation on the wound sites of rats with a full-thickness skin defect. Moreover, the positive role of OLAF in promoting angiogenesis and its possible pathways were clarified in vivo and in vitro. The results showed that the number, length and branches of the blood vessels of the chick embryo chorioallantoic membrane were markedly increased after OLAF treatment. Meanwhile, the in vitro results also revealed that 100 ng/mL OLAF exhibited a promoting effect on the proliferation, migration and tube formation of human umbilical vein endothelial cells. In addition, the potential of OLAF to improve wound angiogenesis was demonstrated to be associated with an up-regulated PI3K/Akt pathway by transcriptome sequencing analysis and the introduction of a PI3K/Akt pathway inhibitor (LY294002). These findings suggest that OLAF has many prospects in the development of drugs for wound healing.

Influence of reductive soil disinfestation or biochar amendment on bacterial communities and their utilization of plant-derived carbon in the rhizosphere of tomato.

Root-associated microorganisms play an important role in plant nutrition and productivity. However, our understanding of how a plant-microbiome system responds to pre-planting soil management remains limited. Here, continuous labeling with 13CO2 gas combined with stable isotope probing (SIP) was applied to explore bacterial utilization of plant-derived carbon (C) in the tomato rhizosphere as affected by biochar amendment or reductive soil disinfestation (RSD). Our results showed that RSD treatment strongly shaped the soil bacterial community composition, while biochar soil amendment had little impact on the community in the rhizosphere of tomato. We observed that the bacterial community in the RSD treatment, which actively utilized plant-derived C, belonged to various phyla (i.e., Proteobacteria, Cyanobacteria, Verrucomicrobia, and Acidobacteria), while the genus Streptomyces (phylum Actinobacteria) was the main bacterial taxa that actively utilized plant-derived C in the biochar and control treatments. This study provides evidence that biochar application or RSD pre-planting soil management practices induced distinct bacterial utilization of plant-derived C, which may in turn regulate plant productivity in agricultural systems. KEY POINTS: • Genus Streptomyces was the main bacterial group utilizing plant-derived carbon in both control and biochar treatments. • Reductive soil disinfestation altered bacterial utilization of plant-derived carbon. • Biochar did not alter the composition of the bacterial communities but had more labeled bacterial taxa utilizing plant-derived carbon.

Optimization of the extraction conditions and dermal toxicity of oil body fused with acidic fibroblast growth factor (OLAF).

INTRODUCTION: Oil body (OB), a subcellular organelle that stores oil in plant seeds, is considered a new transdermal drug delivery system. With the increasing understanding of the OB and its main protein (oleosin), numerous studies have been conducted on OB as "carrier" for the expression of exogenous proteins. In our previous study, oil body fused with aFGF (OLAF) was obtained using a plant oil body expression system that had been preliminarily proven to be effective in accelerating the healing of skin wounds. However, no dermal toxicological information on OLAF is available. OBJECTIVE: To ensure the dermal safety of OLAF, a series of tests (the acute dermal toxicity test, 21-day repeat dermal toxicity test, dermal irritation test and skin sensitisation test) were conducted after optimising the extraction protocol of OLAF. MATERIALS AND METHODS: To improve the extraction rate of OLAF, response surface methodology (RSM) was first employed to optimise the extraction conditions. Then, Wistar rats were exposed to OLAF (400 mg·kg-1 body weight) in two different ways (6 hours/time for 24 hours and 1 time/day for 21 days) to evaluate the acute dermal toxicity and 21-day repeated dermal toxicity of OLAF. In the acute dermal toxicity test, clinical observations were conducted to evaluate the toxicity, behaviour, and health of the animals for 14 consecutive days. Similarly, the clinical signs, body weight, haematological and biochemical parameters, histopathological changes and other indicators were also detected during the 21 days administration. For the dermal irritation test, single and multiple doses of OLAF (125 mg·kg-1 body weight) were administered to albino rabbits for 14 days (1 time/day). The irritation reaction on the skin of each albino rabbit was recorded and scored. Meanwhile, skin sensitisation to OLAF was conducted using guinea pigs for a period of 28 days. RESULTS: Suitable extraction conditions for OLAF (PBS concentration 0.01, pH of PBS 8.6, solid-liquid ratio 1:385 g·mL-1) were obtained using RSM. Under these conditions, the extraction rate and particle size of OLAF were 7.29% and 1290 nm, respectively. In the tests of acute dermal toxicity and 21-day repeated dermal toxicity, no mortality or significant differences were observed in terms of clinical signs, body weight, haematological parameters, biochemical parameters and anatomopathological analysis. With respect to the dermal irritation test and skin sensitisation test, no differences in erythema, oedema or other abnormalities were observed between treatment and control groups on gross and histopathological examinations. CONCLUSIONS: The results of this study suggest that OLAF does not cause obvious toxicity, skin sensitisation or irritation in animals.

Molecular imaging-monitored radiofrequency hyperthermia-enhanced intratumoral herpes simplex virus-thymidine kinase gene therapy for rat orthotopic ovarian cancer.

Objective: To establish the technique of intratumoral combination therapy of radiofrequency hyperthermia (RFH) with herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy for rat ovarian cancers.Material and methods: This study consisted of three parts: (1) in vitro experiments to establish the 'proof of principal' that combination of RFH and HSV-TK gene therapy has the synergistic effect on human ovarian cancer cells; (2) creation of bioluminescence imaging-detectable rat ovarian cancer model; and (3) in vivo experiments using this rat model to validate the technical feasibility of the combination therapy. Cells and nude rats were divided into four groups: (i) combination therapy (HSV-TK/GCV + RFH); (ii) RFH; (iii) HSV-TK/GCV; and (iv) phosphate-buffered saline (PBS). Data were analyzed using Dunnett t-test or Kruskal-Wallis test.Results: Cell proliferation assay demonstrated significantly greater reduction in viable cells with the combination therapy [0.52 (0.43, 0.61)] compared to other treatments [RFH 0.90 (0.84, 0.96), HSV-TK/GCV 0.71 (0.53, 0.88), PBS 1 (1, 1); p < .05]. For 24 rat models with bioluminescence imaging-detectable orthotopic ovarian cancer (n = 6 per group), optical imaging demonstrated significantly decreased relative bioluminescence signal with the combination therapy [0.81 (0.52, 1.08)] compared to other treatments [RFH 3.60 (2.34, 4.86), HSV-TK/GCV 2.21 (1.71, 2.71), PBS 3.74 (3.19, 4.29); p < .001]. Ultrasound imaging demonstrated the smallest relative tumor volume with the combination therapy [0.78 (0.45, 1.11) versus 3.50 (2.67, 4.33), 2.10 (0.83, 3.37), 3.70 (1.79, 5.61); p < .05].Conclusion: The feasibility of intratumoral RFH-enhanced HSV-TK/GCV gene therapy was established on a unique rat model with molecular imaging-detectable orthotopic ovarian cancer.

Oxygen reduction reaction performance of Fe-N/C catalysts from ligand-iron coordinative supramolecular precursors.

Simultaneous introduction of both transition metal and other inorganic elements into the carbon matrix has attracted great attention in the fabrication of carbon materials with high electrochemical properties. Herein, rational design of ligand-iron coordinative supramolecular precursors is achieved for the fabrication of Fe-N/C catalysts, which possess high oxygen reduction reaction (ORR) performance. A series of precursors are prepared by a simple coordination reaction between a three armed catechol monomer and iron ions. Particular interest is focused on tuning the doping species, surface area and morphology of the Fe-N/C catalysts through a simple selection of iron resources. We show that an Fe-N/C catalyst derived from Fe2(SO4)3 at a carbonization temperature of 800 °C, has the optimized ORR performance with an onset potential of 0.930 V and half-wave potential of 0.801 V. Detailed investigation indicates that the synergistic effect among doping elements of nitrogen and sulfur and the unique carbon structure determines the performance of the Fe-N/C catalysts. Our findings may be of significance for the fabrication of doped carbon materials using coordinative supramolecular polymers as precursors.

Growth of Rhodes grass and leaching of ions from seawater neutralized bauxite residues after amendment with gypsum and organic wastes.

A 32-week leaching column study was carried out in the greenhouse to investigate the effects of incorporation of gypsum, cattle manure, biosolids, gypsum plus cattle manure and gypsum plus biosolids into the topsoil layer (0-10 cm) on growth of Rhodes grass, and on root distribution and chemical and microbial properties in the topsoil and subsoil (10-30 cm) layers of seawater neutralized bauxite residues. The columns were leached for a period of 8 weeks prior to sowing Rhodes grass and during that time the bulk of the salts accumulated during seawater neutralization were leached out. The main cation leached was Na+ and the main balancing anions were Cl- and SO42-. During this period the pH of leachates rose from 7 to 8 up to 9-10. At the end of the study, exchangeable Na and pH were lowered in the surface horizon by all treatments with a combination of gypsum plus organic amendments having the greatest effect. The latter treatments also caused a significant decrease in pH, extractable Al and exchangeable Na in the subsoil. Rhodes grass dry matter production followed the order Control < gypsum < cattle manure = gypsum plus cattle manure < biosolids = gypsum plus biosolids. Growth of roots into the subsoil layer was inhibited in the Control and gypsum treatments but when organic amendments were applied, 50% or more of root dry matter was recovered in the subsoil layer. It was concluded that incorporating a combination of gypsum and organic matter into the surface soil is an effective strategy for revegetation of bauxite residue.

Effects of UV-B radiation on the survival, egg hatchability and transcript expression of antioxidant enzymes in a high-temperature adapted strain of Neoseiulus barkeri.

Biological control of spider mites in hot and dry weather is a serious technical issue. A high-temperature adapted strain (HTAS) of the predatory mite Neoseiulus barkeri Hughes was selected from its conventional strain (CS), via long-term heat acclimation and frequent heat hardenings in our previous studies. However, the environment of high temperature is usually associated with enhanced ultraviolet (UV) radiation. In the present study, the physiological effects of UV-B radiation on survival rate and egg damage of N. barkeri were investigated, as well as the activities and expression profiles of antioxidant enzymes to UV-B radiation stress. UV-B radiation had deleterious effects on egg hatchability and survival of N. barkeri. Adults of the HTAS strain were less UV-B resistant than those of the CS strain; they also had lower levels of enzymatic activity of superoxide dismutase (SOD) and catalase against oxidative damage and weaker upregulation of SOD genes. The mRNA expression of three SOD genes of CS adult females immediately increased whereas that of HTAS showed almost no difference under UV-B stress for 1 h. The results showed the HTAS of N. barkeri had lower fitness under UV-B stress compared with the CS of N. barkeri. These results suggested that long-term heat acclimation may exert a profound impact on the developmental physiology of N. barkeri.

Properties of seawater neutralized bauxite residues and changes in chemical, physical and microbial properties induced by additions of gypsum and organic matter.

Seawater neutralization is a technique that can be used to treat bauxite residue prior to its storage but, as yet, no attempts have been made to revegetate it. Seawater neutralized bauxite residue was found to have a pH1:5 of 9.3 and to be highly saline (EC1.5 16.5 dS m-1). After leaching pH1:5 rose to 9.7 and the residue was still highly sodic (ESP = 64-69%). Addition of 1% gypsum, prior to leaching, arrested this increase in pH while with 5% gypsum addition the pH1:5 was lowered to 8.9. Addition of 5% gypsum also reduced ESP to 38% and increased watercress germination in the residue from 58% in control treatments to 88%. The major ions in leachates were Na+ and Cl- and gypsum application increased the quantities of Na+, Ca2+ and SO42- leached. Addition of 6% biosolids or 6% poultry manure added exchangeable cations to the mud and lowered ESP by 5-11%.The EC was 2.8-3.7 (mean 3.1) times higher and pH 0.2-0.7 (mean 0.43) units lower in saturation paste compared with 1:5 soil:water extracts. Addition of amendments had only small effects on physical properties. While organic C content was increased more by biosolids than poultry manure addition the reverse was the case for soluble organic C, microbial biomass C and basal respiration. It was concluded that although seawater neutralization initially lowers the pH of bauxite residues it is unlikely to increase the ease with which they can be revegetated.

Fully human monoclonal antibodies to TRAIL-R1 enhance TRAIL-induced apoptosis via activation of caspase-8 pathway.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or agonistic antibodies targeting TRAIL-receptors (TRAIL-Rs) can selectively induce apoptosis in cancer cells. However, they have limited antitumor efficacy in clinical trials. We previously generated ten fully human monoclonal Abs to TRAIL-receptor type 1 (TR1-mAbs) using immunospot array assay on a chip (ISAAC technology). We found that the TR1-mAbs exhibited different effects on TRAIL-induced apoptosis (enhanced or blocked apoptosis). Here, we further demonstrated that some mAbs competed with TRAIL for binding to TRAIL-R1 expressed on tumor cells that blocked TRAIL-induced apoptosis (B-TR1-Ab), whereas others did not compete with TRAIL that enhanced TRAIL-induced apoptosis (E-TR1-Ab). Combination of E-TR1-Ab (TR1-419) with TRAIL leads to enhanced antitumor activity in various tumor cells in vitro. E-TR1-419 and TRAIL could cooperate to upregulate the mRNA expression and protein levels of TRAIL-R1 and to promote caspase-8 cleavage and increased JNK phosphorylation. Our results suggest that combining E-TR1 Ab with TRAIL could provide a new therapeutic strategy for tumor immunotherapies.

Survival Strategies of the Plant-Associated Bacterium Enterobacter sp. Strain EG16 under Cadmium Stress.

Plant-associated bacteria are of great interest because of their potential use in phytoremediation. However, their ability to survive and promote plant growth in metal-polluted soils remains unclear. In this study, a soilborne Cd-resistant bacterium was isolated and identified as Enterobacter sp. strain EG16. It tolerates high external Cd concentrations (Cd(2+) MIC, >250 mg liter(-1)) and is able to produce siderophores and the plant hormone indole-3-acetic acid (IAA), both of which contribute to plant growth promotion. Surface biosorption in this strain accounted for 31% of the total Cd accumulated. The potential presence of cadmium sulfide, shown by energy-dispersive X-ray (EDX) analysis, suggested intracellular Cd binding as a Cd response mechanism of the isolate. Cd exposure resulted in global regulation at the transcriptomic level, with the bacterium switching to an energy-conserving mode by inhibiting energy-consuming processes while increasing the production of stress-related proteins. The stress response system included increased import of sulfur and iron, which become deficient under Cd stress, and the redirection of sulfur metabolism to the maintenance of intracellular glutathione levels in response to Cd toxicity. Increased production of siderophores, responding to Cd-induced Fe deficiency, not only is involved in the Cd stress response systems of EG16 but may also play an important role in promoting plant growth as well as alleviating the Cd-induced inhibition of IAA production. The newly isolated strain EG16 may be a suitable candidate for microbially assisted phytoremediation due to its high resistance to Cd and its Cd-induced siderophore production, which is likely to contribute to plant growth promotion.

Effects of different fertilizers on the abundance and community structure of ammonia oxidizers in a yellow clay soil.

Yellow clay paddy soil (Oxisols) is a typical soil with low productivity in southern China. Nitrification inhibitors and slow release fertilizers have been used to improve nitrogen fertilizer utilization and reduce environmental impaction of the paddy soil. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in paddy soil have rarely been investigated. In the present work, we compared the influences of several slow release fertilizers and nitrification inhibitors on the community structure and activities of the ammonia oxidizers in yellow clay soil. The abundances and community compositions of AOA and AOB were determined with qPCR, terminal restriction fragment length polymorphism (T-RFLP), and clone library approaches. Our results indicated that the potential nitrification rate (PNR) of the soil was significantly related to the abundances of both AOA and AOB. Nitrogen fertilizer application stimulated the growth of AOA and AOB, and the combinations of nitrapyrin with urea (NPU) and urea-formaldehyde (UF) inhibited the growth of AOA and AOB, respectively. Compared with other treatments, the applications of NPU and UF also led to significant shifts in the community compositions of AOA and AOB, respectively. NPU showed an inhibitory effect on AOA T-RF 166 bp that belonged to Nitrosotalea. UF had a negative effect on AOB T-RF 62 bp that was assigned to Nitrosospira. These results suggested that NPU inhibited PNR and increased nitrogen use efficiency (NUE) by inhibiting the growth of AOA and altering AOA community. UF showed no effect on NUE but decreased AOB abundance and shifted AOB community.

Effects of different sizes of microplastic particles on soil respiration, enzyme activities, microbial communities, and seed germination.

Microplastics (MPs) are emerging pollutants of terrestrial ecosystems. The impacts of MP particle size on terrestrial systems remain unclear. The current study aimed to investigate the effects of six particle sizes (i.e., 4500, 1500, 500, 50, 5, and 0.5 µm) of polyethylene (PE) and polyvinyl chloride (PVC) on soil respiration, enzyme activity, bacteria, fungi, protists, and seed germination. MPs significantly promoted soil respiration, and the stimulating effects of PE were the strongest for medium and small-sized (0.5-1500 µm) particles, while those of PVC were the strongest for small particle sizes (0.5-50 µm). Large-sized (4500 µm) PE and all sizes of PVC significantly improved soil urease activity, while medium-sized (1500 µm) PVC significantly improved soil invertase activity. MPs altered the soil microbial community diversity, and the effects were especially pronounced for medium and small-sized (0.5-1500 µm) particles of PE and PVC on bacteria and fungi and small-sized (0.5 µm) particles of PE on protists. The impacts of MPs on bacteria and fungi were greater than on protists. The seed germination rate of Brassica chinensis decreased gradually with the decrease in PE MPs particle size. Therefore, to reduce the impact of MPs on soil ecosystems, effective measures should be taken to avoid the transformation of MPs into smaller particles in soil environmental management.