TNFSF15 facilitates the differentiation of CD11b^(+) myeloid cells into vascular pericytes in tumors

Objective:Immature vasculature lacking pericyte coverage substantially contributes to tumor growth,drug resistance,and cancer cell dissemination.We previously demonstrated that tumor necrosis factor superfamily 15(TNFSF15)is a cytokine with important roles in modulating hematopoiesis and vascular homeostasis.The main purpose of this study was to explore whether TNFSF15 might promote freshly isolated myeloid cells to differentiate into CD11b^(+) cells and further into pericytes.Methods:A model of Lewis lung cancer was established in mice with red fluorescent bone marrow.After TNFSF15 treatment,CD11b^(+) myeloid cells and vascular pericytes in the tumors,and the co-localization of pericytes and vascular endothelial cells,were assessed.Additionally,CD11b^(+) cells were isolated from wild-type mice and treated with TNFSF15 to determine the effects on the differentiation of these cells.Results:We observed elevated percentages of bone marrow-derived CD11b^(+)myeloid cells and vascular pericytes in TNFSF15-treated tumors,and the latter cells co-localized with vascular endothelial cells.TNFSF15 protected against CD11b^(+)cell apoptosis and facilitated the differentiation of these cells into pericytes by down-regulating Wnt3a-VEGFR1 and up-regulating CD49e-FN signaling pathways.Conclusions:TNFSF15 facilitates the production of CD11b^(+) cells in the bone marrow and promotes the differentiation of these cells into pericytes,which may stabilize the tumor neovasculature.

Effects of nitrogen and phosphorus additions on soil nematode community of soybean farmland

The nitrogen(N)and phosphorus(P)addition promotes the abundance of soybean soil nematodes.The addition of nitrogen can alleviate the suppression of phosphorus on nematodes.Phosphorus addition affects nematode abundance by ammonium nitrogen.

土地利用方式对黄河漫滩土壤微生物群落结构和多样性的影响

土壤微生物群落及其多样性是土壤碳和养分循环的重要生物指标。土地利用变化是影响漫滩生态系统土壤微生物群落组成的主要决定因素。然而,土壤微生物群落的结构和多样性如何响应土地利用变化,以及这些变化的主要驱动因素是什么,仍不清楚。本研究在黄河漫滩进行,以检验土地利用变化对土壤微生物群落的影响。选取了4种土地利用类型(灌丛、农田、草地和森林),其中以灌木地为对照,用磷脂脂肪酸测量了土壤微生物组成和多样性。研究结果表明,土地利用变化显著影响了总细菌、真菌和革兰氏阳性/阴性细菌。与灌丛相比,农田的总磷脂脂肪酸和细菌较高,森林的真菌较高。土壤pH值和全磷是微生物组成的最佳预测因子,分别解释了37%和26%的变异性。土壤全氮和硝态氮是影响微生物多样性的主要因素。花生农田的土壤碳含量、土壤碳储量、磷脂脂肪酸总量和微生物多样性最高,表明漫滩具有巨大的碳汇潜力。这些研究结果表明,黄河漫滩的农田对于维持土壤微生物群落和土壤碳固存至关重要。

Significant reduction in friction and wear of a high-entropy alloy via the formation of self-organized nanolayered structure

Sliding wear-induced nanolayering and its positive impact on wear resistance have been observed in conventional binary alloys with a matrix of high stacking fault energy(SFE),but this concept has never been reported in high-entropy alloys(HEAs)with low SFE.Here,we design and fabricate a(CoCrFeNi)_(90)Ag_(10)HEA,consisting of a face-center-cubic(fcc)CoCrFeNi HEA matrix with low SFE and uniformly dispersed Ag precipitates.In comparison with CoCrFeNi,a significant reduction in friction and wear was found in(CoCrFeNi)_(90)Ag_(10)HEA through the spontaneous formation of nanolayered subsurface microstructure during wear.The finding suggests a novel approach for designing HEAs that can achieve low friction and wear.

Soil microbial community structure and activity in a 100-year-old fertilization and crop rotation experiment

Aims Nitrogen(N)fertilization and lime addition may affect soil micro-bial and nematode communities and ecosystem functions through changing environmental conditions,such as soil pH and soil organic carbon.The objectives of this experiment were to examine the impact of N input and liming on soil microbial and nematode communities and to identify the key environmental determinant of community composition in a century-old fertilization and crop rota-tion experiment.Methods The field experiment consisting of a 3-year crop rotation regime was established in 1911 in southeastern USA.Four treatments,(i)no-input control,(ii)NPK with winter legume,(iii)PK with legume and lime and(iv)NPK with legume and lime,were included in this study.soil samples collected at the 0-5 cm depth were used to determine the bacterial growth rate by the 3H-thymidine incorporation technique.Incorporation of 13C into neutral lipids,glycolipids and phospholipid fatty acids(PlFas)was measured after incubation of soil with 13C-labeled acetate for 24 h.Free-living nematodes in fresh soil were extracted using a density sucrose centrifugal flotation method and identified to trophic group level.Important Findingsliming resulted in a 10-fold increase in bacterial growth rates compared with the no-input control,whereas N fertilization had no significant effect.multivariate analysis of PlFa profiles showed that soil microbial community composition was different among the four treatments;the difference was primarily driven by soil pH.PlFas indicative of gram-negative bacteria covaried with soil pH,but not those of fungi and actinobacteria.liming enhanced 13C incorpora-tion into neutral lipids,glycolipids and phospholipids by 2-15 times.In addition,13C incorporation into 16:0,16:1ω9,18:1ω9,18:1ω7 and 18:2ω6 were greater than other PlFas,suggesting that gram-negative bacteria and fungi were more active and sensitive to simple C input.bacterivorous nematodes were the dominant trophic group in the soil,but no significant differences in nematode communities were found among the treatments.our results suggest that soil pH had a greater impact than N fertilization on soil microbial community composition and activity in a crop rotation system including legumes.

Considerable impacts of litter inputs on soil nematode community composition in a young Acacia crassicapa plantation

Aboveground litter inputs and root exudates provide basal resources for soil communities,however,their relative contributions to soil food web are still not well understood.Here,we conducted a field manipulative experiment to differentiate the effects of litter inputs and living root on nematode community composition of surface and subsoils in a young Acacia crassicapa plantation in southern China.Our results showed that both litter addition and root presence significantly enhanced soil nematode abundance by 17.3%and 35.3%,respectively.Litter addition altered nematode trophic group composition,decreased fungivore to bacterivore ratio,and enhanced maturity index and structure index,which led to a bacterial-based energy channel and a more complex food web structure.However,root presence had a limited impact on the nematode community composition and ecological indices.Despite nematodes surface assembly,soil depth did not affect nematode trophic group composition or ecological index.Our findings highlight the importance of litter inputs in shaping soil nematode community structure and regulating soil energy channel.

Inhibition of the negative effect of high glucose on osteogenic differentiation of bone marrow stromal cells by silicon ions from calcium silicate bioceramics

Human bone marrow stem cells(hBMSCs)are exploited for miscellaneous applications in bone tissue engineering where they are mainly used as seed cells.However,high glucose(HG)environment has negative impacts on the proliferation and osteogenic differentiation of hBMSCs,thus reducing the bone formation in diabetic patients.In our former research works,we discovered that silicon(Si)ions extracted from silicate-based bioceramics are able to stimulate the proliferation and osteogenic differentiation of hBMSCs under normal culture condition.This study aimed to investigate if Si ions could prevent HG-induced inhibition of proliferation and osteogenesis of hBMSCs.We found that 2.59ppm concentration of Si ions promoted the proliferation of hBMSCs under HG condition.The results from alkaline phosphatase(ALP)activity assay,Alizarin red S staining and quantitative real-time PCR analysis of osteogenic genes(BMP2,RUNX2,ALP,COL1 and OCN)demonstrated that the 15.92ppm concentration of Si ions prevented HG-induced inhibition of the osteogenic differentiation of hBMSCs.Moreover,application of Si ions reduced the level of reactive oxygen species in HG-treated hBMSCs.In HG-treated hBMSCs following 15.92ppm Si ions treatment,activation of BMP2/SMAD signaling pathway was detected,as indicated by the increased expression of BMP2 receptors and its downstream genes such as SMAD1,SMAD4 and SMAD5.Taken together,we provide evidence that the specific concentration of Si ions compensated HG-induced inhibition of proliferation and osteogenic differentiation of hBMSCs through antioxidant effect and modulation of BMP2/SMAD pathway.The results suggest that silicate-based bioceramics might be good scaffold biomaterials for bone engineering applications in diabetes patients.

Measuring fracture toughness of human dental enamel at small scale using notched microcantilever beams

Dental enamel is the most mineralised hard tissue with a complex hierarchically organised anisotropic structure and it protects human teeth from mechanical damage during the dental function.Due to the sample size constraints,the available data for quantitative evaluation of the fracture toughness of human enamel is very limited.Here,on the basis of microstructural characterisation,the fracture toughness of human dental enamel at small scale with respect to orientation was measured using notched microcantilever beams fabricated by focussed ion beam.The fracture toughness of human enamel with perpendicular orientation was measured to be 1.244±0.12 MPa·m^(1/2),80%tougher than that of in-plane parallel orientation(0.698±0.18 MPa·m^(1/2)).The present results are expected to provide deep insights into cusp fractures and the synthesis of enamel-like restorative materials.