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.

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.

The proliferation of beneficial bacteria influences the soil C, N, and P cycling in the soybean-maize intercropping system.

Soybean-maize intercropping system can improve the utilization rate of farmland and the sustainability of crop production systems. However, there is a significant gap in understanding the interaction mechanisms between soil carbon (C), nitrogen (N), and phosphorus (P) cycling functional genes, rhizosphere microorganisms, and nutrient availability. To reveal the key microorganisms associated with soil nutrient utilization and C, N, and P cycling function in the soybean-maize intercropping system, we investigated the changes in soil properties, microbial community structure, and abundance of functional genes for C, N, and P cycling under soybean-maize intercropping and monocropping at different fertility stages in a pot experiment. We found that there was no significant difference in the rhizosphere microbial community between soybean-maize intercropping and monocropping at the seeding stage. As the reproductive period progressed, differences in microbial community structure between intercropping and monocropping gradually became significant, manifesting the advantages of intercropping. During the intercropping process of soybean and maize, the relative abundance of beneficial bacteria in soil rhizosphere significantly increased, particularly Streptomycetaceae and Pseudomonadaceae. Moreover, the abundances of C, N, and P cycling functional genes, such as abfA, mnp, rbcL, pmoA (C cycling), nifH, nirS-3, nosZ-2, amoB (N cycling), phoD, and ppx (P cycling), also increased significantly. Redundancy analysis and correlation analysis showed that Streptomycetaceae and Pseudomonadaceae were significantly correlated with soil properties and C, N, and P cycling functional genes. In brief, soybean and maize intercropping can change the structure of microbial community and promote the proliferation of beneficial bacteria in the soil rhizosphere. The accumulation of these beneficial bacteria increased the abundance of C, N, and P cycling functional genes in soil and enhanced the ability of plants to fully utilize environmental nutrients and promoted growth.

Research progress in biological control of tomato bacterial wilt.

Bacterial wilt caused by the infection of Ralstonia solanacearum, is one of the most harmful diseases to tomatoes, one of the most important greenhouse vegetables in China. R. solanacearum can survive and remain active in the deep soil for a long time, and the chemical control of tomato bacterial wilt is consequently limited. In this study, we introduced the characteristics of tomato bacterial wilt disease and the types of R. solanacearum, and systematically reviewed the research progresses of biological control methods from the aspects of botanical insecticides, agricultural antibiotics, biocontrol bacteria. We emphatically introduced the principle and current status of these methods, discussed the limitations and the improvement strategies, and prospected a new environmental protection and efficient biological control system based on micro-ecological regulation would be the development direction of biological control of tomato bacterial wilt.

[Research progress on primers and molecular ecology of comammox Nitrospira]. / å®Œå ¨æ°¨æ°§åŒ–èŒçš„åˆ†å­ç”Ÿæ€å­¦ç ”ç©¶è¿›å±•.

Nitrification is a key process in nitrogen cycling, which has received considerable attention in the research field of soil biochemistry. In 2015, the discovery of complete ammonia oxidizers (Comammox) challenged conventional two-step nitrification perspective, which represented a paradigm shift in the understanding of soil nitrogen cycling. Comammox are a group of microorganisms capable of conducting both steps of nitrification. In this review, we summarized current understan-ding of the molecular ecology of comammox, including specific molecular biomarkers for comammox, phylogenetic and genomic surveys of comammox and particularly the distribution, diversity and ecological significance of comammox in soil. Further studies should focus on: 1) designing specific molecular biomarkers to examine the distribution and diversity of comammox; 2) optimizing cultivation techniques to isolate/enrich comammox cultures and expending our insights into physiological traits of comammox; 3) characterizing their distribution and in situ activities to elucidate the contribution of comammox processes to soil nitrification and their ecological features, which may assist in unco-vering the mechanisms of nitrogen cycling and promote the environmental protection of soil ecosystem.

Effects of sangu decoction on osteoclast activity in a rat model of breast cancer bone metastasis.

Bone metastasis (BM) is a major clinical problem for which current treatments lack full efficacy. The Traditional Chinese Medicine (TCM) Sangu Decoction (SGD) has been widely used to treat BM in China. However, no in vivo experiments to date have investigated the effects of TCM on osteoclast activity in BM. In this study, the protective effect and probable mechanism of SGD were evaluated. The model was established using the breast cancer MRMT-1 cells injected into the tibia of rat. SGD was administrated, compared with Zoledronic acid as a positive control. The development of the bone tumor and osteoclast activity was monitored by radiological analysis. TRAP stain was used to identify osteoclasts quantity and activity. TRAP-5b in serum or bone tumor and TRAP mRNA were also quantified. Radiological examination showed that SGD inhibited tumor proliferation and preserved the cortical and trabecular bone structure. In addition, a dramatic reduction of TRAP positive osteoclasts was observed and TRAP-5b levels in serum and bone tumor decreased significantly. It also reduced the mRNA expression of TRAP. The results indicated that SGD exerted potent antiosteoclast property that could be directly related to its TRAP inhibited activity. In addition it prevented bone tumor proliferation in BM model.

[Expression and significance of insulin-like growth factor-1 and insulin-like growth factor binding protein-3 in hepatocyte steatosis model].

OBJECTIVE: To investigate the expression of IGF-1 and IGFBP-3 in nonalcoholic fatty steatosis hepatocyte models induced by oleic acid. METHOD: Nonalcoholic fatty steatosis hepatocyte models induced by oleic acid on immortalized human hepatocyte, Oil red O staining and intracellular triglycerides were detected for observing the situation of IHH cells fatty degeneration. IHH cells were divided into control group, NAFLD group, which the control group cultured in DMEM/F12 medium, NAFLD group were treated with oleic acid, 0.5 mmol/L treatment for 72 h. The expression of mRNA and protein of IGF-1 and IGFBP3 were measured by immunofluorescent staining, Western blot and RT-PCR methods. Between the two groups were compared using the t- test. RESULTS: The steatosis models of the hepatocytes were established successfully with 0.5 mmol/L oleic acid. Lipid droplets were observed through Oil red O staining. The level of hepatocyte TG was increased (275.7+/-27.2) mug/mg from (150.2+/-15.6) mug/mg (t = 21.67, P less than 0.01). Compared with the control group, the mRNA of IGF-1 (0.76+/-0.04 vs 4.82+/-1.51, t = 17.915, P less than 0.01), IGFBP-3 (1.58+/-0.93 vs 5.41+/-1.37, t = 12.893, P less than 0.01) and protein expression of IGF-1 (1.00+/-0.29 vs 2.56+/-0.71, t = 29.17, P less than 0.01), IGFBP-3 (0.65+/-0.36 vs 1.23+/-0.91, t = 32. 12, P less than 0.01) significantly decreased in oleic acid-treated group. The results of immunofluorescence staining also confirm the significantly decreased protein expression of IGF-1 and IGFBP-3 in NAFLD group compared with control group. CONCLUSION: The expression of IGF-1 and IGFBP-3 decreased in nonalcoholic fatty steatosis hepatocyte models, which will provide the experimental basis for the further study of the mechanism of the limited height of some children with non-alcoholic fatty liver disease in clinical.

Effect of Sangu Decoction () on metastatic bone destruction in rats with mammary cancer.

OBJECTIVE: To study and evaluate the effect of Sangu Decoction (SGD, ) on the bone destruction due to mammary cancer metastasis. METHODS: Metastasis rat mammary tumor-1 cells were transplanted into the left hind limb tibia of SD rats to establish the bone metastasis of the mammary cancer model. The modeled rats were treated with SGD for observing its effect on rats' pain behavior, including 50% paw withdrawal threshold (50% PWT) after von Frey fiber stimulation, burden difference of bilateral feet, and thermal withdrawal latency (TWL), with zoledronic acid as the positive control. Moreover, the damage in the tibia sample of rats was scored by an iconographic method, and the bone mineral density (BMD) as well as the bone mineral content (BMC) were estimated. RESULTS: The model established showed characteristics of mixed metastasis, revealing the manifestations of tumor development, bone destruction, cancerous pain, etc. In the SGD-treated group, 50% PWT was prolonged (8.13 ± 4.76 vs. 2.30 ± 2.19), and TWL was longer (3.48 ± 0.62 s vs. 2.89 ± 0.26 s) than those in the control group, respectively (P<0.05 or P<0.01). Iconographic scoring also showed improvement of BMD (0.134 ± 0.009 vs. 0.120 ± 0.007, P<0.01) and an elevating trend of BMC in the SGD-treated group. CONCLUSION: SGD could effectively alleviate the cancerous pain of bone metastasis and mitigate the metastasis that cause osteolytic destruction of bone.

[Effect of magnesium lithospermate B on endothelial cells in human aorta after free radical injury].

OBJECTIVE: To study the cardiovascular effects of magnesium lithospermate B (MLB), a water soluble extract from red sage root, on human aortic endothelial cells (HAECs) proliferation and in treating free radical injured endothelial cells, so as to further understand the cardiovascular pharmacological mechanism of MLB. METHODS: HAECs of 3-6 passages were used in the experiment. MLB of different concentrations was used to treat the cells, and cell proliferation was observed using morphological and MTT method. The free radical injured model cell was made by glucose-glucose oxidase method for observing the effect of MLB on its microstructure by transmission electron microscopy. RESULTS: MLB in concentration of 1.0 mg/ml and 0.5 mg/ml had significant cytotoxicity (P<0.01), when its concentration was lower than 0.2 mg/ml, the drug showed no adverse reaction on cell proliferation. MLB showed significantly cell protective effect against free radical injury, the effect in protecting ultrastructure of cells, such as mitochondria, could be demonstrated in transmission electron microscopy. CONCLUSION: MLB showed a low cytotoxicity on HAECs, it could obviously protect cells from free radical injury.