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.     

Detailed finite element modelling of deep needle insertions into a soft tissue phantom using a cohesive approach

Detailed finite element modelling of needle insertions into soft tissue phantoms encounters difficulties of large deformations, high friction, contact loading and material failure. This paper demonstrates the use of cohesive elements in high-resolution finite element models to overcome some of the issues associated with these factors. Experiments are presented enabling extraction of the strain energy release rate during crack formation. Using data from these experiments, cohesive elements are calibrated and then implemented in models for validation of the needle insertion process. Successful modelling enables direct comparison of finite element and experimental force–displacement plots and energy distributions. Regions of crack creation, relaxation, cutting and full penetration are identified. By closing the loop between experiments and detailed finite element modelling, a methodology is established which will enable design modifications of a soft tissue probe that steers through complex mechanical interactions with the surrounding material.     

An ESR contrast agent is transported to rat liver through organic anion transporter

Carboxy PROXYL is a useful extracellular paramagnetic contrast reagent in electron spin resonance (ESR) and magnetic resonance imaging (MRI). Active transfer of the probe was investigated using an in situ liver model in rats. Carboxy PROXYL, a nitroxyl spin probe, was perfused into in situ liver perfusion system from Wistar rats. Concentration of nitroxyl form of the spin probe in effluent increased gradually after introducing perfusate with the spin probe and reached a plateau. The disappearance of Carboxy PROXYL from the perfusate was 40%, which could not be explained with its partition coefficient. Administration of non-selective inhibitors of organic anion transporters, p-aminohippuric acid and penicillin G, inhibited competitively and in a dose dependent manner the transfer of Carboxy PROXYL into rat liver in situ, resulting in increases of Carboxy PROXYL in the effluent. The results demonstrate that there is an active transfer system of an ESR contrast reagent into in situ rat liver through organic anion transporters.     

Purification and Characterization op a 31-Kilodalton Iron-Regulated Periplasmic Protein from Pasteurella Haenolytica A1

ABSTRACT

A prominent iron-regulated periplasmic protein was purified from Pasteurella haemolytica grown in an iron-deficient chemically defined medium. The protein was purified by anion exchange chromatography and appeared as a single band by SDS-PAGE with a molecular weight of 32,000. A yield of five mg was obtained from 91 mg of protein extract. The iron-regulated protein existed as a monomer in the native state with an average molecular weight of 29,877 as determined by analytical ultracentrifugation. The protein had a molecular weight of 30,880 as determined by matrix-assisted laser desorption mass spectrometry, hence the protein is referred to as the 31 kDa protein. Isoelectric focusing showed four bands with pIs of 7.15, 6.8, 6.6, and 5.9, The secondary structure of the protein was determined by circular dichroism and contained 16% α-helical structure. The N-terminal sequence, EPFKVVTTFTVIQDIAQNVAGDKAT, showed a 95% identity with the 31 kDa iron-binding protein from Haemophilus influenzae. Isolation and characterization of iron-regulated proteins are of particular interest because of their potential roles in iron assimilation and microbial virulence.     

Rapid methods of detecting the target molecule in immunohistology using a bioluminescence probe

We demonstrate a novel rapid direct detection method for immunohistochemistry, using a bioluminescent probe. An anti‐CEA antibody‐fused far‐red bioluminescent protein can monitor the accumulation of this type of probe in tumour tissues. The bimodal spectrum (λ_max = 460 and 675 nm) of this bioluminescent probe is extremely stable under different conditions of pH and ion concentration. The sensitivity of our bioluminescent labelling was at the same level of enzymatic labelling, e.g. peroxidase, as an indirect system. Our novel technique is simple and can shorten the pretreatment time of paraffin sections to around 30 min. The utility of our bioluminescent labelling covers all imaging in vitro, in vivo and ex vivo, suggesting that our antibody‐fused bioluminescent probe has the potential to detect tumour antigens with a high sensitivity in routine immune histological examinations. Copyright © 2012 John Wiley & Sons, Ltd.