Interaction of multiple factors with a GC-rich rlement within the mitogen responsive region of the human transferrin receptor gene

Nuclear factors from HeLa cells were isolated by elution of DNA-cellulose bound proteins with a double stranded synthetic oligonucleotide corresponding to the region from ?34 to ?79 of the human transferrin receptor (TR) gene promoter. The eluted proteins were further purified and separated from the oligonucleotide by ion exchange chromatography. Proteins within the resulting fraction bound with specificity to the TR promoter. Retardation gel analysis and competition with specific double-stranded oligonucleotides show that multiple factors present in this fraction compete for binding within the same region of the TR promoter. Footprinting experiments demonstrate that these factors contact a GC-rich element that is within the region that is required for enhanced expression of the gene in proliferating cells. One of the factors protects an extended DNA sequence but, still contacts the GC-rich element.     

Penetration of soil aggregates of finite size

Summary Maximum penetrometer pressure was measured on artificial soil aggregates of finite size (2–29 mm) using blunt probes (total cone angle 60°) driven at 3 mm min⁻¹. Maximum penetrometer pressure increased asymptotically with increase in dimensionless aggregate radius,b/a, wherea andb are the probe and aggregate radii, respectively. A theory was developed for penetration of blunt probes into soil aggregates of finite size. The theory assumed that plastic failure occurs out to a radius,R, and that beyond this only elastic straining occurs. This theory can be applied to estimate the radial and tangential stresses adjacent to a blunt probe. The estimated radial and tangential stresses increased with increase in dimensionless aggregate radius,b/a. The radius of the plastic front,R, around the probe is predicted to increase with increased aggregate size. The results also demonstrate the effect of soil shear cohesion and internal friction angle onR. The results are discussed with reference to root penetration.     

基于Taqman-MGB探针的亚稀褶红菇实时荧光定量PCR检测方法

本研究建立了一种基于Taqman-MGB探针的亚稀褶红菇Russula subnigricans实时荧光定量PCR检测方法。根据亚稀褶红菇与其近似种的内转录间隔区（internal transcribed spacers,ITS）序列差异,设计合成1对引物和1条特异性Taqman-MGB探针,并用常见有毒红菇种类进行验证。结果显示,引物特异性良好,仅亚稀褶红菇出现荧光信号,完成整个检测过程只需2h。该法能够为毒蘑菇中毒的快速检测提供技术支持。     

Ultraviolet Photoemission Spectroscopy and Kelvin Probe Measurements on Metal Halide Perovskites: Advantages and Pitfalls

In this essay, a case study is presented on the electronic structure of several metal halide perovskites (MHP) using Kelvin probe (KP)‐based surface photovoltage (SPV) measurements and ultraviolet photoemission spectroscopy (UPS) to demonstrate the advantages, but also the pitfalls, of using these techniques to characterize the surfaces of these materials. The first part addresses the loss of halide species from perovskite surfaces upon supragap illumination in vacuum. This has the potential to cause both a long‐term alteration of the sample work function and a modification of the KP tip during SPV measurements. If undetected, this leads to a misinterpretation of the MHP surface potential. The second part illustrates the difficulties in determining the valence band maximum (VBM) of MHP surfaces with UPS and stresses the importance of taking into account the low density of states at the VBM edge. Given this circumstance, specific care must be taken to eliminate measurement artifacts in order to ascertain the presence or absence of low densities of electronic gap states above the VBM. This essay also highlights issues such as film degradation, nonequilibrium situations (e.g., SPV), and satellite emissions, which occur during photoemission spectroscopy.     

基于整树称重法的Granier经验公式对毛白杨树干液流测定的适用性

为了评估Granier经验公式在树干液流测定中的适用性,以毛白杨为对象,利用热扩散式探针法(TDP)测定树木的液流速率,以整树称重法进行同步测定,对比分析Granier经验公式在毛白杨树干液流测定中是否存在误差,并对整树称重法测定的蒸腾速率与热扩散法测定的温差系数K进行幂指数回归拟合,建立校正的Granier公式。结果表明:与整树称重法测定的蒸腾速率相比,通过Granier经验公式计算的液流速率低估了67.7%;建立了毛白杨的Granier校正公式F_d=0.0135K^0.6952(R²=0.77),校正后Granier公式的计算结果与整树称重法测定的蒸腾速率相比仅降低了3.4%,具有较好的一致性。因此,采用Granier经验公式计算毛白杨树干液流速率需进行校正。     

铽(Ⅲ)离子及其复合物:从发光特性到传感应用

稀土元素也称镧系元素,因其独特的发光性质和配位性质,其发光复合物被广泛研究于生物技术领域。其中稀土铽(Ⅲ)离子复合物因具有优异的光谱特性,关于其研究呈现出快速的发展趋势。主要从其发光特性的角度出发,探讨了其发光机理,并对铽(Ⅲ)离子与不同有机化合物结合形成的发光铽配合物以及铽(Ⅲ)离子及其配合物与不同纳米材料形成的复合物进行了分类综述。此外,还详细地阐述了铽离子及其复合物在荧光探针、生物传感器、药物递送、细胞成像、癌症治疗等相关领域的应用。最后,对其今后发展趋势和潜在的研究价值进行了展望。     

Evaluating human autosomal loci for sexually antagonistic viability selection in two large biobanks

Sex and sexual differentiation are pervasive across the tree of life. Because females and males often have substantially different functional requirements, we expect selection to differ between the sexes. Recent studies in diverse species, including humans, suggest that sexually antagonistic viability selection creates allele frequency differences between the sexes at many different loci. However, theory and population-level simulations indicate that sex-specific differences in viability would need to be very large to produce and maintain reported levels of between-sex allelic differentiation. We address this contradiction between theoretical predictions and empirical observations by evaluating evidence for sexually antagonistic viability selection on autosomal loci in humans using the largest cohort to date (UK Biobank, n = 487,999) along with a second large, independent cohort (BioVU, n = 93,864). We performed association tests between genetically ascertained sex and autosomal loci. Although we found dozens of genome-wide significant associations, none replicated across cohorts. Moreover, closer inspection revealed that all associations are likely due to cross-hybridization with sex chromosome regions during genotyping. We report loci with potential for mis-hybridization found on commonly used genotyping platforms that should be carefully considered in future genetic studies of sex-specific differences. Despite being well powered to detect allele frequency differences of up to 0.8% between the sexes, we do not detect clear evidence for this signature of sexually antagonistic viability selection on autosomal variation. These findings suggest a lack of strong ongoing sexually antagonistic viability selection acting on single locus autosomal variation in humans.     

β-Carboline-Based pH Fluorescent Probe and Its Application for Monitoring Enzymatic Ester Hydrolysis

A novel pH-activatable fluorescent probe, 1-(propan-2-yl)-9H-pyrido[3,4-b]indole-3-carboxylic acid ( L-1 ), based on β-carboline derivatives, has been developed, which displays significant fluorescent response toward pH variation with high selectivity, good photo-stability and favorable pKa value. Moreover, L-1 can dynamically monitor the release of protons during ester hydrolysis reaction in consistent with enzymatic kinetics manner.