万顺铅锌矿区蜈蚣草内生细菌砷氧化基因(aoxB)的多样性分析

【背景】近年来,由于金属矿的开采和冶炼、砷产品的加工与使用、煤的燃烧等各种因素,导致土壤环境中的砷污染越来越严重,导致许多人暴露于极度危险的砷毒毒害之下。【目的】研究四川的万顺铅锌矿区蜈蚣草根组织内生细菌aoxB基因的多样性,为提高土壤重金属污染生态修复效率提供理论依据。【方法】利用实时荧光定量PCR (Real-time quantitative PCR,qPCR)和限制性片段长度多态性(Restriction fragment length polymorphism,RFLP)技术,对四川省汉源县万顺铅锌矿区蜈蚣草根组织内生细菌aoxB基因表达量及多样性进行研究。【结果】qPCR结果表明,不同采样点间的蜈蚣草根组织内生细菌aoxB基因表达量存在明显差异,表现为选矿区进山口弃渣场尾矿区矿口。酶切图谱结果表明,不同采样点蜈蚣草根组织内生细菌aoxB基因多样性存在明显差异,多样性指数表现为尾矿矿口弃渣场进山口选矿区。Pearson相关分析显示,aoxB基因的表达量与重金属As之间呈显著负相关(P0.05),多样性指数则与重金属Pb和As之间呈极显著正相关(P0.01)。系统发育分析显示,aoxB基因的优势菌群为α-变形菌门(Alphaproteobacteria)。【结论】蜈蚣草根组织中存在丰富的含aoxB基因内生细菌种群,这些内生细菌表现出潜在的应用价值。     

Synergistic Effect of Bimetallic MOF Modified Separator for Long Cycle Life Lithium-Sulfur Batteries

Severe polysulfide dissolution and shuttling are the main challenges that plague the long cycle life and capacity retention of lithium-sulfur (Li-S) batteries. To address these challenges, efficient separators are designed and modified with a dual functional bimetallic metal-organic framework (MOF). Flower-shaped bimetallic MOFs (i.e., Fe-ZIF-8) with nanostructured pores are synthesized at 35 °C in water by introducing dopant metal sites (Fe), which are then coated on a polypropylene (PP) separator to provide selective channels, thereby effectively inhibiting the migration of lithium polysulfides while allowing homogeneous transport of Li-ions. The active sites of the Fe-ZIF-8 enable electrocatalytic conversion, facilitating the conversion of lithium polysulfides. Moreover, the developed separator can prevent dendrite formation due to the uniform pore size and hence the even Li-ion transport and deposition. A coin cell using a Fe-ZIF-8/PP separator with S-loaded carbon cathode displayed a high cycle life of 1000 cycles with a high initial discharge capacity of 863 mAh g⁻¹ at 0.5 C and a discharge capacity of 746 mAh g⁻¹ at a high rate of 3 C. Promising specific capacity has been documented even under high sulfur loading of 5.0 mg cm⁻² and electrolyte to the sulfur ratio (E/S) of 5 µL mg⁻¹.     

Hyper-radiosensitivity affects low-dose acute myeloid leukemia incidence in a mathematical model

In vitro experiments show that the cells possibly responsible for radiation-induced acute myeloid leukemia (rAML) exhibit low-dose hyper-radiosensitivity (HRS). In these cells, HRS is responsible for excess cell killing at low doses. Besides the endpoint of cell killing, HRS has also been shown to stimulate the low-dose formation of chromosomal aberrations such as deletions. Although HRS has been investigated extensively, little is known about the possible effect of HRS on low-dose cancer risk. In CBA mice, rAML can largely be explained in terms of a radiation-induced Sfpi1 deletion and a point mutation in the remaining Sfpi1 gene copy. The aim of this paper is to present and quantify possible mechanisms through which HRS may influence low-dose rAML incidence in CBA mice. To accomplish this, a mechanistic rAML CBA mouse model was developed to study HRS-dependent AML onset after low-dose photon irradiation. The rAML incidence was computed under the assumptions that target cells: (1) do not exhibit HRS; (2) HRS only stimulates cell killing; or (3) HRS stimulates cell killing and the formation of the Sfpi1 deletion. In absence of HRS (control), the rAML dose-response curve can be approximated with a linear-quadratic function of the absorbed dose. Compared to the control, the assumption that HRS stimulates cell killing lowered the rAML incidence, whereas increased incidence was observed at low doses if HRS additionally stimulates the induction of the Sfpi1 deletion. In conclusion, cellular HRS affects the number of surviving pre-leukemic cells with an Sfpi1 deletion which, depending on the HRS assumption, directly translates to a lower/higher probability of developing rAML. Low-dose HRS may affect cancer risk in general by altering the probability that certain mutations occur/persist.

     

A new clustering-based routing method in the mobile internet of things using a krill herd algorithm

Cluster Computing - Internet of things has become an essential principle of human life with the widespread acceptance of intelligent environments, where everyday objects can communicate through the...     

Renal Cell Carcinoma Metastatic to the Liver: Early Response Assessment after Intraarterial Therapy Using 3D Quantitative Tumor Enhancement Analysis

PURPOSELiver metastases from renal cell carcinoma (RCC) are not uncommon in the course of disease. However, data about tumor response to intraarterial therapy (IAT) are scarce. This study assessed whether changes of enhancing tumor volume using quantitative European Association for the Study of the Liver (qEASL) on magnetic resonance imaging (MRI) and computed tomography (CT) can evaluate tumor response and predict overall survival (OS) early after therapy.RESULTSMean qEASL (cm³) decreased from 93.5 to 67.2 cm³ (P= .004) and mean qEASL (%) from 63.1% to 35.6% (P= .001). No significant changes were observed using other response criteria. qEASL was the only significant predictor of OS when used to stratify patients into responders and nonresponders with median OS of 31.9 versus 11.1 months (hazard ratio [HR], 0.43; 95% confidence interval [CI], 0.19-0.97; P= .042) for qEASL (cm³) and 29.9 versus 10.2 months (HR, 0.09; 95% CI, 0.01-0.74; P= .025) for qEASL (%).CONCLUSIONThree-dimensional (3D) quantitative tumor analysis is a reliable predictor of OS when assessing treatment response after IAT in patients with RCC metastatic to the liver. qEASL outperforms conventional non-3D methods and can be used as a surrogate marker for OS early after therapy.     

Effects of Plasma Membrane Cholesterol Level and Cytoskeleton F-Actin on Cell Protrusion Mechanics

Protrusions are deformations that form at the surface of living cells during biological activities such as cell migration. Using combined optical tweezers and fluorescent microscopy, we quantified the mechanical properties of protrusions in adherent human embryonic kidney cells in response to application of an external force at the cell surface. The mechanical properties of protrusions were analyzed by obtaining the associated force-length plots during protrusion formation, and force relaxation at constant length. Protrusion mechanics were interpretable by a standard linear solid (Kelvin) model, consisting of two stiffness parameters, k ₀ and k ₁ (with k ₀>k ₁), and a viscous coefficient. While both stiffness parameters contribute to the time-dependant mechanical behavior of the protrusions, k ₀ and k ₁ in particular dominated the early and late stages of the protrusion formation and elongation process, respectively. Lowering the membrane cholesterol content by 25% increased the k ₀ stiffness by 74%, and shortened the protrusion length by almost half. Enhancement of membrane cholesterol content by nearly two-fold increased the protrusion length by 30%, and decreased the k ₀ stiffness by nearly two-and-half-fold as compared with control cells. Cytoskeleton integrity was found to make a major contribution to protrusion mechanics as evidenced by the effects of F-actin disruption on the resulting mechanical parameters. Viscoelastic behavior of protrusions was further characterized by hysteresis and force relaxation after formation. The results of this study elucidate the coordination of plasma membrane composition and cytoskeleton during protrusion formation.     

Gawky is a component of cytoplasmic mRNA processing bodies required for early Drosophila development

In mammalian cells, the GW182 protein localizes to cytoplasmic bodies implicated in the regulation of messenger RNA (mRNA) stability, translation, and the RNA interference pathway. Many of these functions have also been assigned to analogous yeast cytoplasmic mRNA processing bodies. We have characterized the single Drosophila melanogaster homologue of the human GW182 protein family, which we have named Gawky (GW). Drosophila GW localizes to punctate, cytoplasmic foci in an RNA-dependent manner. Drosophila GW bodies (GWBs) appear to function analogously to human GWBs, as human GW182 colocalizes with GW when expressed in Drosophila cells. The RNA-induced silencing complex component Argonaute2 and orthologues of LSm4 and Xrn1 (Pacman) associated with 5'-3' mRNA degradation localize to some GWBs. Reducing GW activity by mutation or antibody injection during syncytial embryo development leads to abnormal nuclear divisions, demonstrating an early requirement for GWB-mediated cytoplasmic mRNA regulation. This suggests that gw represents a previously unknown member of a small group of genes that need to be expressed zygotically during early embryo development.     

Association of a Genetic Variant in the Cyclin-Dependent Kinase Inhibitor 2B with Risk of Pancreatic Cancer

Background:Pancreatic cancer (PC) is among the most aggressive tumors with a poor prognosis, indicating the need for the identification of a novel prognostic biomarker for risk stratifications. Recent genome-wide association studies have demonstrated common genetic variants in a region on chromosome 9p21 associated with an increased risk of different malignancies.Methods:In the present study, we explore the possible relationship between genetic variant, rs10811661, and gene expression of CDKN2B in 75 pancreatic cancer patients, and 188 healthy individuals. DNAs were extracted and genotyping and gene expression were performed by TaqMan real-time PCR and RT-PCR, respectively. Logistic regression was used to assess the association between risk and genotypes, while the significant prognostic variables in the univariate analysis were included in multivariate analyses.Results:The patients with PDAC had a higher frequency of a TT genotype for rs10811661 than the control group. Also, PDAC patients with dominant genetic model, (TT + TC), was associated with increased risk of developing PDAC (OR= 14.71, 95% CI [1.96-110.35], p= 0.009). Moreover, patients with CC genotype had a higher expression of CDKN2B, in comparison with TT genotype.Conclusion:Our findings demonstrated that CDKN2A/B was associated with the risk of developing PDAC, supporting further investigations in the larger and multicenter setting to validate the potential value of this gene as an emerging marker for PDAC. Key Words: CDKN2A/B, Rs10811661, Pancreatic cancer, Prognostic biomarker     

Investigation into the structural, morphological, mechanical and thermal behaviour of bacterial cellulose after a two-step purification process

Bacterial cellulose (BC) is a natural hydrogel, which is produced by Acetobacter xylinum (recently renamed Gluconacetobacter xylinum) in culture and constitutes of a three-dimensional network of ribbon-shaped bundles of cellulose microfibrils. Here, a two-step purification process is presented that significantly improves the structural, mechanical, thermal and morphological behaviour of BC sheet processed from these hydrogels produced in static culture. Alkalisation of BC using a single-step treatment of 2.5 wt.% NaOH solution produced a twofold increase in Young's modulus of processed BC sheet over untreated BC sheet. Further enhancements are achieved after a second treatment with 2.5 wt.% NaOCl (bleaching). These treatments were carefully designed in order to prevent any polymorphic crystal transformation from cellulose I to cellulose II, which can be detrimental for the mechanical properties. Scanning electron microscopy and thermogravimetric analysis reveals that with increasing chemical treatment, morphological and thermal stability of the processed films are also improved.