Formulation of novel lipid-coated magnetic nanoparticles as the probe for in vivo imaging

Background  

Application of superparamagnetic iron oxide nanoparticles (SPIOs) as the contrast agent has improved the quality of magnetic resonance (MR) imaging. Low efficiency of loading the commercially available iron oxide nanoparticles into cells and the cytotoxicity of previously formulated complexes limit their usage as the image probe. Here, we formulated new cationic lipid nanoparticles containing SPIOs feasible for in vivo imaging.     

Fluorine-18 labeled galactosylated chitosan for asialoglycoprotein-receptor-mediated hepatocyte imaging

Galactosylated chitosan (GC) was prepared by reacting lactobionic acid with water-soluble chitosan. GC was labeled with fluorine-18 by conjugation with N-succinimidyl-4-¹⁸F-fluorobenzoate ([¹⁸F]SFB) under a slightly basic condition. After rapid purification with HiTrap desalting column, [¹⁸F]FB-GC was obtained with high radiochemical purity (>97%) determined by radio-HPLC. The total reaction time for [¹⁸F]FB-GC was about 150 min. Typical decay-corrected radiochemical yield was about 4–8%. Ex vivo biodistribution in normal mice showed that [¹⁸F]FB-GC had moderate activity accumulation in liver with very good retention (11.13 ± 1.63, 10.97 ± 1.90 and 10.77 ± 0.95% ID/g at 10, 60, 120 min after injection, respectively). The other tissues except kidney showed relative low radioactivity accumulation. The high liver/background ratio affords promising biological properties to get clear images. The specific binding of this radiotracer to the ASGP receptor was confirmed by blocking experiment in mice. Compared with the non-blocking group the hepatic uptake of [¹⁸F]FB-GC significantly declined in all selected time points. The better liver retention properties of [¹⁸F]FB-GC than that of albumin based imaging agents may improve imaging quality and simplify pharmacokinetic model of liver function in the future application with PET imaging.     

枣疯病植原体tuf和rp基因的克隆与序列分析

【目的】枣疯病是一种重要的植原体病害,本研究旨在明确北京及河北地区枣疯病植原体的分类地位,为枣疯病在亚组水平上分类提供一定的参考依据。【方法】利用植原体通用引物fTufu/rTufu和rp(v)F1A/rp(v)R1A对北京和河北地区枣疯病植原体延伸因子tuf基因和核糖体蛋白基因(rp)进行PCR扩增并进行核苷酸序列测定及相似性分析。【结果】获得北京地区JWB-XFSZ株系、JWB-XFDO株系以及河北地区JWB-TXSZ株系的tuf基因片段均为824 bp;北京地区JWB-XFSZ株系的rp基因片段为1196 bp。经序列相似性比较表明:tuf基因与16SrV组的葡萄黄叶病(Flavescence dorée)相似性最高,为92.84%,而与已经公布的其它地区(陕西杨凌)的枣疯病植原体tuf基因相似性较低,为57.29%;关于rp基因,北京地区枣疯病JWB-XFSZ株系与16SrV组的枣疯病泰山株系(JWB-Taishan)以及大麻丛枝病植原体(HFWB)相似性最高,均为99.83%,与16SrV组的成员相似性均在96%以上。【结论】北京与河北地区枣疯病植原体具有较高的相似性,而在tuf基因水平上,与陕西地区枣疯病植原体具有较大的差异;本研究中北京与河北两地区枣疯病植原体归属于16SrV组。     

Spectroscopic investigation on the toxic interaction of melamine with herring sperm DNA

The toxic interaction of melamine with herring sperm DNA (hs‐DNA) was investigated by using fluorescence and UV–vis absorption spectra techniques. The experimental results showed that the toxic interaction between melamine and hs‐DNA occurred. Fluorescence quenching experiments indicated the existence of electrostatic binding between melamine and hs‐DNA. The binding constants K_A and the binding site numbers were calculated by means of the Stern–Volmer equation and were 9.8 × 10⁴ L mol^?1 and 1.3, respectively. Both the results of fluorescence spectra and UV–vis absorption spectra verified that there are electrostatic binding between melamine and hs‐DNA. The possibility in the presence of a classical intercalation binding mode could be ruled out by using DNA unwinding experiments. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:323–329, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.20341     

固相小柱对沙苑子总黄酮萃取方法的研究

目的:以沙苑子总黄酮为研究对象,考察固相萃取小柱的洗脱条件,确定固相萃取沙苑子总黄酮的实验方法。方法:以不同浓度的甲醇对不同填料的固相小柱进行洗脱,将洗脱液在岛津VP-ODS(150 mm×4.6 mm,5μm)柱上进行高效液相色谱分析。通过比较不同浓度及体积甲醇的萃取效率,确定沙苑子苷在固相萃取小柱上的洗脱条件。结果:用正相氨基小柱以50%甲醇洗脱效果好,回收率可达100%。结论:经试验,正相氨基小柱对沙苑子苷的萃取回收率约为100%,适用于沙苑子总黄酮中沙苑子苷的分析。     

Increased expression of MAP KINASE KINASE7 causes deficiency in polar auxin transport and leads to plant architectural abnormality in Arabidopsis

Polar auxin transport (PAT) plays a crucial role in the regulation of many aspects of plant growth and development. We report the characterization of a semidominant Arabidopsis thaliana bushy and dwarf1 (bud1) mutant. Molecular genetic analysis indicated that the bud1 phenotype is a result of increased expression of Arabidopsis MAP KINASE KINASE7 (MKK7), a member of plant mitogen-activated protein kinase kinase group D. We showed that BUD1/MKK7 is a functional kinase and that the kinase activity is essential for its biological functions. Compared with the wild type, the bud1 plants develop significantly fewer lateral roots, simpler venation patterns, and a quicker and greater curvature in the gravitropism assay. In addition, the bud1 plants have shorter hypocotyls at high temperature (29 degrees C) under light, which is a characteristic feature of defective auxin action. Determination of tritium-labeled indole-3-acetic acid transport showed that the increased expression of MKK7 in bud1 or the repressed expression in MKK7 antisense transgenic plants causes deficiency or enhancement in auxin transport, indicating that MKK7 negatively regulates PAT. This conclusion was further substantiated by genetic and phenotypic analyses of double mutants generated from crosses between bud1 and the auxin-related mutants axr3-3, tir1-1, doc1-1, and atmdr1-1.     

Molecular profile of the unique species of traditional Chinese medicine,Chinese seahorse (Hippocampus kuda Bleeker)

A cDNA library of male Chinese seahorse (Hippocampus kuda Bleeker) was constructed to investigate the molecular profile of seahorse as one of the most famous traditional Chinese medicine materials, and to reveal immunological and physiological mechanisms of seahorse as one of the most primitive vertebrates at molecular level. A total of 3372 expressed sequence tags (ESTs) consisting of 1911 unique genes (345 clusters and 1566 singletons) were examined in the present study. Identification of the genes related to immune system, paternal brooding and physiological regulation provides not only valuable insights into the molecular mechanism of immune system in teleost fish but also plausible explanations for pharmacological activities of Chinese seahorse. Furthermore, the occurrence of high prevalent C-type lectins suggested that a lectin-complement pathway might exert a more dominant function in the innate immune system of teleost than mammal. Carbohydrate recognition domain (CRD) without a collagen-like region in the lectins of seahorse was likely an ancient characteristic of lectins similar to invertebrates.     

High coding density on the largest Paramecium tetraurelia somatic chromosome

Paramecium, like other ciliates, remodels its entire germline genome at each sexual generation to produce a somatic genome stripped of transposons and other multicopy elements. The germline chromosomes are fragmented by a DNA elimination process that targets heterochromatin to give a reproducible set of some 200 linear molecules 50 kb to 1 Mb in size. These chromosomes are maintained at a ploidy of 800n in the somatic macronucleus and assure all gene expression. We isolated and sequenced the largest megabase somatic chromosome in order to explore its organization and gene content. The AT-rich (72%) chromosome is compact, with very small introns (average size 25 nt), short intergenic regions (median size 202 nt), and a coding density of at least 74%, higher than that reported for budding yeast (70%) or any other free-living eukaryote. Similarity to known proteins could be detected for 57% of the 460 potential protein coding genes. Thirty-two of the proteins are shared with vertebrates but absent from yeast, consistent with the morphogenetic complexity of Paramecium, a long-standing model for differentiated functions shared with metazoans but often absent from simpler eukaryotes. Extrapolation to the whole genome suggests that Paramecium has at least 30,000 genes.     

Spatio-temporal patterns of soil available nutrients following experimental disturbance in a pine forest

Although disturbance is known to alter soil nutrient heterogeneity, it remains unclear whether spatial patterns in soil nutrients after disturbance follow predictable temporal changes that reflect underlying processes. This study examined the effects of tree harvesting and girdling on overall variability, geostatistical patterns, and resource congruence of soil available nutrients in a mature Pinus elliottii Engelm. forest. The two disturbances led to different patterns of vegetation removal, forest floor redistribution, and revegetation, but showed similar post-disturbance changes in overall soil nutrient variability. Soil nutrient variability increased after both disturbances by more than 5-fold, and then decreased, returning to the undisturbed level in 4 years. Spatial structures assessed using geostatistics did not show predictable temporal trends. However, girdled plots showed more persistent spatial structures in soil nutrients than harvested plots, and had semivariogram ranges mostly equal to or less than 10 m, reflecting effects of persistent and spatially stable patches of undisturbed hardwoods that had an average patch size of 10 m. Resource congruence examined with Spearman rank correlations was nil before disturbance, increased after disturbance and then became nil again by the 4th year post-disturbance. The timing of the increase was related to treatment, occurring in the 1st year after disturbance in the girdled plots, but not until the 2nd year in the harvested plots. These two patterns of congruence were potentially caused by different rates of nutrient patch formation and resource uptake by plants during early succession. Although temporal changes in soil heterogeneity have been documented previously, the present study indicates that temporal trends in nutrient variability after disturbance may be predictable, and that the marked changes in spatio-temporal patterns of soil nutrients as a result of disturbance are ephemeral.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Identification of fecal microbiome signatures associated with familial longevity and candidate metabolites for healthy aging

Gut microbiota associated with longevity plays an important role in the adaptation to damaging stimuli accumulated during the aging process. The mechanism by which the longevity-associated microbiota protects the senescent host remains unclear, while the metabolites of the gut bacteria are of particular interest. Here, an integrated analysis of untargeted metabolomics and 16S rRNA gene sequencing was used to characterize the metabolite and microbiota profiles of long-lived individuals (aged ≥90 years) in comparison to old-elderly (aged 75–89 years), young-elderly (aged 60–74 years), and young to middle-aged (aged ≤59 years) individuals. This novel study constructed both metabolite and microbiota trajectories across aging in populations from Jiaoling county (the seventh longevity town of the world) in China. We found that the long-lived group exhibited remarkably differential metabolomic signatures, highlighting the existence of metabolic heterogeneity with aging. Importantly, we also discovered that long-lived individuals from the familial longevity cohort harbored a microbiome distinguished from that of the general population. Specifically, we identified that the levels of a candidate metabolite, pinane thromboxane A2 (PTA2), which is positively associated with aging, were consistently higher in individuals with familial longevity and their younger descendants than in those of the general population. Furtherly, functional analysis revealed that PTA2 potentiated the efficiency of microglial phagocytosis of β-amyloid 40 and enhanced an anti-inflammatory phenotype, indicating a protective role of PTA2 toward host health. Collectively, our results improve the understanding of the role of the gut microbiome in longevity and may facilitate the development of strategies for healthy aging.