A genetically and functionally diverse group of non-diazotrophic Bradyrhizobium spp. colonizes the root endophytic compartment of Arabidopsis thaliana

BACKGROUND

Diazotrophic Bradyrhizobium spp. are well known for their ability to trigger nodule formation on a variety of legume species. In nodules, Bradyrhizobium utilizes plant-derived carbohydrates in exchange for fixed nitrogen. The genes essential for the nodulation and nitrogen-fixation trait are clustered in a genomic region, which is known as the 'symbiotic island'. Recently, novel non-diazotrophic Bradyrhizobium spp. have been found to be highly abundant in soils, suggesting that these species can also have a 'free-living' life history. However, whether non-diazotrophic Bradyrhizobium spp. can live in association with plants remains elusive.

RESULTS

In this study, we show that Bradyrhizobium spp. are common root endophytes of non-legume plant species - including Arabidopsis thaliana (Arabidopsis) - grown in an ecological setting. From a single Arabidopsis root, four Bradyrhizobium sp. strains (designated MOS001 to MOS004) were isolated. Comparative genome analysis revealed that these strains were genetically and functionally highly diverse, but did not harbour the nodulation and the nitrogen fixation gene clusters. Comparative colonization experiments, with MOS strains and nitrogen-fixing symbiotic strains, revealed that all tested Bradyrhizobium spp. can colonize the root endophytic compartment of Arabidopsis.

CONCLUSION

This study provides evidence that both diazotrophic and non-diazotrophic Bradyrhizobium spp. colonize the root endophytic compartment of a wide variety of plant species, including the model species Arabidopsis. This demonstrates that plant roots form a major ecological niche for Bradyrhizobium spp., which might be ancestral to the evolution of the nodulation and nitrogen-fixation trait in this genus.

The optimal anatomic site for a single slice to estimate the total volume of visceral adipose tissue by using the quantitative computed tomography (QCT) in Chinese population

BACKGROUND/OBJECTIVES

To investigate the relationship between the cross-sectional visceral adipose tissue (VAT) areas at different anatomic sites and the total VAT volume in a healthy Chinese population using quantitative computed tomography (QCT), and to identify the optimal anatomic site for a single slice to estimate the total VAT volume.

SUBJECTS/METHODS

A total of 389 healthy Chinese subjects aged 19-63 years underwent lumbar spine QCT scans. The cross-sectional area of total adipose tissue and VAT were measured using the tissue composition module of the software (QCT Pro, Mindways) at each intervertebral disc level from T₁₂/L₁ to L₅/S₁, as well as at the umbilical level. The total VAT volume was defined as the fat areas multiplied by the height of vertebral body for all six slices. Statistical analysis was performed to determine the correlation between single-slice VAT areas and the total VAT volume. Moreover, the optimal anatomic site for a single slice to estimate the total VAT volume was identified by multiple regression analysis.

RESULTS

The cross-sectional area of VAT and subcutaneous adipose tissue (SAT) measured at each anatomic site was all highly correlated with the total VAT volume and the total SAT volume (r = 0.89-0.98). Additionally, the VAT area measured at the L₂/L₃ level showed the strongest correlation with the total VAT volume (r = 0.98, P < 0.001). Covariates including age, gender, BMI, waist, and hypertension make a slight effect on the prediction of the total VAT volume.

CONCLUSION

It is feasible to perform measurements of VAT area on a single slice at L₂/L₃ level for estimating the total VAT volume.

Period Increase and Amplitude Distribution of Kink Oscillation of Coronal Loop

Coronal loops exist ubiquitously in the solar atmosphere. These loops puzzle astronomers over half a century. Solar magneto-seismology (SMS) provides a unique way to constrain the physical parameters of coronal loops. Here, we study the evolution of oscillations of a coronal loop observed by the Atmospheric Imaging Assembly (AIA). We measure geometric and physical parameters of the loop oscillations. In particular, we find that the mean period of the oscillations increased from 1048 to 1264 s during three oscillatory cycles. We employ the differential emission measure method and apply the tools of SMS. The evolution of densities inside and outside the loop is analyzed. We found that an increase of density inside the loop and decrease of the magnetic field strength along the loop are the main reasons for the increase in the period during the oscillations. Besides, we also found that the amplitude profile of the loop is different from a profile would it be a homogeneous loop. It is proposed that the distribution of magnetic strength along the loop rather than density stratification is responsible for this deviation. The variation in period and distribution of amplitude provide, in terms of SMS, a new and unprecedented insight into coronal loop diagnostics.

[Clinical significance of targeting drug-based molecular biomarkers expression in ovarian clear cell carcinoma]

Objective: To assess the expression level of targeting drug-based molecular biomarkers in ovarian clear cell carcinoma (OCCC) tissues and its clinical significance. Methods: A total of 63 OCCC patients included 40 primary OCCC and 23 recurrent OCCC for secondary cytoreductive surgery (SCS), who had received primary surgeries at Fudan University Shanghai Cancer Center between January, 2008 and December, 2015 were enrolled, and immunohistochemistry SP method was used to test human epidermal growth factor receptor (EGFR), human epidermal growth factor receptor-2 (HER2), aurora kinase A (AURKA), breast cancer susceptibility gene 1 (BRCA1), BRCA2 and programmed death-ligand 1 (PD-L1)protein expression in paraffin-embedded tissues. Results: The positive rates of EGFR, HER2, AURKA,BRCA1, BRCA2 and PD-L1 in primary and recurrent tumor tissues were respectively 20% (8/40) vs 30% (7/23) , 22% (9/40) vs 35% (8/23) , 38% (15/40) vs 35% (8/23) , 42% (17/40) vs 39% (9/23) , 20% (8/40) vs 22% (5/23) , 25% (10/40) vs 17% (4/23) , and there were no significant differences between primary and recurrent OCCC (all P>0.05). χ(2)-test or Fisher exact analysis revealed that HER2 expression in recurrent tumor tissues had a relationship with chemoresistance (P<0.05), while the expression of other biomarkers showed no significant relationship with chemoresistance (all P>0.05). Further, Kaplan-Meier survival analysis showed that patients with HER2 and AURKA-positive expression had a significantly shorter progression-free survival time in primary OCCC (4 months vs 10 months, log-rank test, P<0.05 for HER2; and 4 months vs 10 months, P<0.05 for AURKA); and a shorter overall survival time after SCS in recurrent OCCC (10 months vs 44 months, P<0.05 for HER2; and 13 months vs 43 months, P<0.05 for AURKA). However, multivariate Cox proportional hazards regression analysis indicated that none of these 6 biomarkers was independent risk factor of progression-free survival time of primary OCCC or overall survival time after SCS for recurrent OCCC (P>0.05). Conclusion: HER2 and AURKA could serve as prognostic factors in ovarian clear cell carcinoma.

Morphable 3D mesostructures and microelectronic devices by multistable buckling mechanics

Three-dimensional (3D) structures capable of reversible transformations in their geometrical layouts have important applications across a broad range of areas. Most morphable 3D systems rely on concepts inspired by origami/kirigami or techniques of 3D printing with responsive materials. The development of schemes that can simultaneously apply across a wide range of size scales and with classes of advanced materials found in state-of-the-art microsystem technologies remains challenging. Here, we introduce a set of concepts for morphable 3D mesostructures in diverse materials and fully formed planar devices spanning length scales from micrometres to millimetres. The approaches rely on elastomer platforms deformed in different time sequences to elastically alter the 3D geometries of supported mesostructures via nonlinear mechanical buckling. Over 20 examples have been experimentally and theoretically investigated, including mesostructures that can be reshaped between different geometries as well as those that can morph into three or more distinct states. An adaptive radiofrequency circuit and a concealable electromagnetic device provide examples of functionally reconfigurable microelectronic devices.

Organocatalytic reductive coupling of aldehydes with 1,1-diarylethylenes using an in situ generated pyridine-boryl radical

A pyridine-boryl radical promoted reductive coupling reaction of aldehydes with 1,1-diarylethylenes has been established.

A pyridine-boryl radical promoted reductive coupling reaction of aldehydes with 1,1-diarylethylenes has been established via a combination of computational and experimental studies. Density functional theory calculations and control experiments suggest that the ketyl radical from the addition of the pyridine-boryl radical to aldehydes is the key intermediate for this C–C bond formation reaction. This metal-free reductive coupling reaction features a broad substrate scope and good functional compatibility.

Low molecular weight polyethylenimine-grafted soybean protein gene carriers with low cytotoxicity and greatly improved transfection in vitro

A series of gene carriers (SP-PEI) have been synthesized by acylation reaction between soybean protein and branched polyethylenimine with low molecular weight of 600, 1200 and 1800 Da, and designed as SP-PEI600, SP-PEI1200 and SP-PEI1800, respectively. SP-PEI could effectively condense plasmid DNA into nanoscale polyplexes with size range of 100-200 nm, and exhibited much lower cytotoxicity against 293T and SH-SY5Y cells than that of branched polyethylenimine (25 kDa). In vitro gene transfection demonstrated that SP-PEI/DNA complex displayed increased transfection against 293T and SH-SY5Y cells with the increase of the weight ratio of SP-PEI/DNA complex with or without 10% serum. At weight ratio of 24, SP-PEI1800/DNA polyplexes showed the highest transfection on SH-SY5Y cells, which was almost three folds higher than PEI (25 kDa). Furthermore, these SP-PEIs/DNA polyplexes could effectively transfect 293T and SH-SY5Y cells with or without 10% serum, suggesting their excellent serum tolerance.

Effects of coexisting BDE-47 on the migration and biodegradation of BDE-99 in river-based aquifer media recharged with reclaimed water

Two prominent polybrominated diphenyl ether (PBDE) congeners have been included in the persistent organic pollutant list, 2,2',4,4',5-tetrabromodiphenyl ether (BDE-99) and 2,2,4,4'-tetrabromodiphenyl ether (BDE-47), which have been detected in treated municipal wastewater, river water, and sediments in China. A lab-scale column experiment was established to investigate the effects of the competitive sorption of BDE-47 on BDE-99 biodegradation and migration in two types of river-based aquifer soils during groundwater recharge with reclaimed water. Two types of recharge columns were used, filled with either silty clay (SC) or black carbon-amended silty clay (BCA). The decay rate constants of BDE-99 in the BCA and SC systems were 0.186 and 0.13 m^-1 in the single-solute system and 0.128 and 0.071 m^-1 in the binary-solute system, respectively, showing that the decay of BDE-99 was inhibited by the coexistence of BDE-47. This was particularly evident in the SC system because the higher hydrophobicity of BDE-99 determined the higher affinity and competition for sorption sites onto black carbon. The biodegradation of BDE-99 was suppressed by the coexistence of BDE-47, especially in the SC system. Lesser-brominated congeners (BDE-47 and BDE-28) and higher-brominated congeners (BDE-100, BDE-153, BDE-154, and BDE-183) were generated in the four recharge systems, albeit at different ratios. Bacterial biodiversity was influenced by the presence of BDE-47 in the SC system, while it had no significant effect on the BCA system, because the high sorption capacity of black carbon on the hydrophobic PBDEs effectively reduced their toxicity. The ranking order of the most abundant classes changed markedly due to the coexistence of BDE-47 in both the SC and BCA systems. The ranking order of the most abundant genera changed from Azospira, Methylotenera, Desulfovibrio, Methylibium, and Bradyrhizobium to Halomonas, Hyphomicrobium, Pseudomonas, Methylophaga, and Shewanella, which could be involved in PBDE degradation.

Nitrogen removal performance and microbial community changes in subsurface wastewater infiltration systems (SWISs) at low temperature with different bioaugmentation strategies

Poor nitrogen removal efficiency (mainly nitrate, NO₃^--N) at low temperatures strongly limits application of subsurface wastewater infiltration systems (SWISs). Seven psychrophilic strains (heterotrophic nitrifying bacteria and aerobic denitrifying bacteria) were isolated and added to SWISs to investigate the effect of embedding and direct-dosing bioaugmentation strategies on sewage treatment performance at low temperature. Both bioaugmentation strategies improved ammonium (NH₄⁺-N) removal efficiencies, and the embedding strategy also exhibited satisfactory NO₃^--N and total nitrogen (TN) removal efficiencies. Pyrosequencing results of the bacterial 16S rRNA gene indicated that the embedding strategy significantly decreased the indigenous soil microbial diversity (p < .05) and altered the bacterial community structure, significantly increasing the relative abundance of Clostridia, which have good nitrate-reducing activity.

A novel biocompatible zwitterionic polyurethane with AIE effect for cell imaging in living cells

In this work, a novel and stable zwitterionic polymer (TPE-CB PUs) was prepared to realize a cellular imaging system. TPE was conjugated into the backbone of zwitterionic polyurethane, which could be well dispersed in aqueous solution and emitted strong blue fluorescence because the TPE segment was aggregated in the core of TPE-CB PUs micelles. More importantly, the TPE-CB PUs micelles showed significant stability in a large pH window and with different storage times. In addition, the micelles exhibited low cytotoxicity in HeLa cells and mainly distributed in the cytoplasm after being incubated with cells. The outstanding properties of TPE-CB PUs combining the merits of AIE and a zwitterionic segment highlight its potential for use as a cell imaging material with remarkable capability.

In this work, a novel and stable zwitterionic polymer (TPE-CB PUs) was prepared to realize a cellular imaging system.

A biomimetic fluorescent chemosensor for highly sensitive zinc(ii) detection and its application for cell imaging

To fabricate a novel biomimetic fluorescent chemosensor, PSaAEMA-co-PMPC was synthesized via atom transfer radical polymerization, and this copolymer could be used for the detection of zinc(ii) and cell imaging. A series tests with various metal ions verified the specific fluorescence response behavior. This novel biomimetic fluorescent chemosensor exhibits excellent selectivity for Zn²⁺ ions over a wide range of tested metal ions in an aqueous solution. Moreover, cytotoxicity and bio-imaging tests were conducted to study the potential bio-application of the chemosensor. Owing to the biomimetic portion (phosphorylcholine), this copolymer possesses outstanding biocompatibility and could clearly image cells. The results indicated that PSaAEMA-co-PMPC has great potential for application in zinc(ii) detection and cell imaging.

To fabricate a novel biomimetic fluorescent chemosensor, PSaAEMA-co-PMPC was synthesized via atom transfer radical polymerization, and this copolymer could be used for the detection of zinc(ii) and cell imaging.

Total synthesis of the isoquinoline alkaloid decumbenine BviaRu(iii)-catalyzed C–H activation

Decumbenine B could be easily synthesized from commercially available materials by only five steps with an overall yield of 26.1%.

Collagen-based three-dimensional culture microenvironment promotes epithelial to mesenchymal transition and drug resistance of human ovarian cancerin vitro

OV-NC and OV-206 cells cultured in collagen I hydrogel scaffolds, could gradually generate multicellular spheroids.

A circular white-light flare with impulsive and gradual white-light kernels

White-light flares are the flares with emissions visible in the optical continuum. They are thought to be rare and pose the most stringent requirements in energy transport and heating in the lower atmosphere. Here we present a nearly circular white-light flare on 10 March 2015 that was well observed by the Optical and Near-infrared Solar Eruption Tracer and Solar Dynamics Observatory. In this flare, there appear simultaneously both impulsive and gradual white-light kernels. The generally accepted thick-target model would be responsible for the impulsive kernels but not sufficient to interpret the gradual kernels. Some other mechanisms including soft X-ray backwarming or downward-propagating Alfvén waves, acting jointly with electron beam bombardment, provide a possible interpretation. However, the origin of this kind of white-light kernel is still an open question that induces more observations and researches in the future to decipher it.

Increased expression of hepcidin and associated upregulation of JAK/STAT3 signaling in human gastric cancer

Gastric cancer is one of the most common malignancies with high cancer-associated mortality rate globally. Hepcidin is the peptide hormone, which is critically important in the regulation of systemic iron homeostasis. Cumulating evidence has reported that the disturbed local expression of hepcidin may serve as a predictive biomarker in assessing the clinical outcomes in a range of cancer types. However, the expression profile of hepcidin in human gastric cancer is remains to be investigated. In the present retrospective study, using archived paraffin-embedded tissue blocks, the local production of hepcidin by immunohistochemical analysis was detected, and then its correlation with clinicopathological characteristics in human gastric cancer was evaluated. In parallel, using western blotting, quantitative reverse transcription polymerase chain reaction and chromatin immunoprecipitation assay, the local status of Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling in response to inflammatory stimuli mediated by interleukin (IL)-6, which in turn regulates transcriptional activity of hepcidin gene (HAMP) was also assessed. The results indicated that, the local production of hepcidin was significantly elevated in tumor tissues compared with adjacent non-tumor tissues, and was tightly correlated with increasing tumor stages according to the tumor node metastasis (TNM) classification. In addition, JAK/STAT3 signaling and the STAT3 binding affinity to the HAMP gene promoter were significantly enhanced, in parallel with an increased expression of hepcidin, in tumor tissues compared with adjacent non-tumor tissues. Collectively, the present study indicated that local expression of hepcidin in gastric cancer tumor tissues was positively correlated with increasing tumor stages, which may be closely associated with the upregulation of IL-6-mediated JAK/STAT3 signaling in human gastric cancer.