脂多糖通过补体途径诱导小鼠产生白三烯B4

目的:研究脂多糖(LPS)对人血清中补体系统的激活及在小鼠模型中诱导产生白三烯B4(LTB4)。方法:LPS包被ELISA板,利用血清中补体C4、C3沉积实验检测补体成分被LPS活化的情况,通过尾静脉注射小鼠LPS后不同时间点ELISA定量检测LTB4,评价补体系统的活化和炎症因子的产生。结果与结论:血清系统ELISA检测发现LPS可以激活补体系统,且以凝集素途径为主;动物实验中LTB4被LPS诱导后1～3 h达到峰值,之后回落。C1INH对血清补体活化和动物模型中LTB4的产生均有显著抑制。     

Engineering dihydropteroate synthase (DHPS) for efficient expression on M13 phage

Phage display is a commonly used selection technique in protein engineering, but not all proteins can be expressed on phage. Here, we describe the expression of a cytoplasmic homodimeric enzyme dihydropteroate synthetase (DHPS) on M13 phage, established by protein engineering of DHPS. The strategy included replacement of cysteine residues and screening for periplasmic expression followed by random mutagenesis and phage display selection with a conformation-specific anti-DHPS antibody. Cysteine replacement alone resulted in a 12-fold improvement in phage display of DHPS, but after random mutagenesis and three rounds of phage display selection, phage display efficiency of the library had improved 280-fold. Most of the selected clones had a common Asp96Asn mutation that was largely responsible for the efficient phage display of DHPS. Asp96Asn affected synergistically with the cysteine replacing mutations that were needed to remove the denaturing effect of potential wrong disulfide bridging in phage display. Asp96Asn alone resulted in a 1.8-fold improvement in phage display efficiency, but in combination with the cysteine replacing mutations, a total of 130-fold improvement in phage display efficiency of DHPS was achieved.     

Models for chromatid interference with applications to recombination data

Genetic interference means that the occurrence of one crossover affects the occurrence and/or location of other crossovers in its neighborhood. Of the three components of genetic interference, two are well modeled: the distribution of the number and the locations of chiasmata. For the third component, chromatid interference, there exists only one model. Its application to real data has not yet been published. A further, new model for chromatid interference is presented here. In contrast to the existing model, it is assumed that chromatid interference acts only in the neighborhood of a chiasma. The appropriateness of this model is demonstrated by its application to three sets of recombination data. Both models for chromatid interference increased fit significantly compared to assuming no chromatid interference, at least for parts of the chromosomes. Interference does not necessarily act homogeneously. After extending both models to allow for heterogeneity of chromatid interference, a further improvement in fit was achieved.     

Rational design and purification of human Bruton's tyrosine kinase SH3-SH2 protein for structure-function studies

Bruton's tyrosine kinase (Btk) is a cytoplasmic protein tyrosine kinase consisting of N-terminal pleckstrin homology (PH) domain followed by Tec homology (TH) domain, Src homology 3 and 2 (SH3 and SH2) domains, and a C-terminal kinase domain. Mutations in the human BTK gene cause the severe immunodeficiency disease X-linked agammaglobulinemia (XLA). The structural and functional basis of several XLA-causing mutations remains unknown, since only the structures of the PH and SH3 domains of human Btk are currently available. In this study, we overexpressed and purified a protein consisting of the SH3 and SH2 domains of human Btk for biochemical and structural analysis. The purified protein was only partially soluble and had a tendency to dimerize, which made it unsuitable for further studies. To overcome the problems of low solubility and dimerization, subdomain interactions were engineered without altering the function of the protein.     

The female genital system of Ooperipatellus decoratus (Onychophora, Peripatopsidae): an ultrastructural study

The female genital system of the oviparous peripatopsid Ooperipatellus decoratus consists of an ovary, oviducts equipped with receptacula seminis and additional pouches, uteri, and a vagina. It is examined using transmission and scanning electron microscopy. The ovary is made up of paired ovarian tubes united anteriorly and posteriorly and differentiated into a sterile dorsal part and a fertile ventral part with exogenous oocytes. Fertilization presumably occurs in the oviducts once the oocytes pass the receptaculum seminis. Although the receptacula seminis have been reported to occur in juvenile O. decoratus females only, the present study reveals that they are present in adult females as well. Their wall consists of a cuboidal epithelium covered with a thin collagen-muscle layer. The additional pouches are projections of the oviducts facing the receptacula seminis. They are distally closed to the haemocoel by a flattened epithelium and lack external muscle cells. A thin collagen layer is only found proximally. The uteri are characterized by a columnar epithelium with folded cell membranes allowing extension of the uteri, thus facilitating the passage of the large uterine eggs towards the vagina. Another dominating feature of the uteri is a distally increasing secretory production, which probably contributes to chorion development. Cilia occurring along the entire length of the uteri are considered to assist in the transport of eggs towards the vagina.     

Genetic control of lipids in the mouse cross DU6i × DBA/2

An F₂ pedigree based on the mouse lines DU6i and DBA/2 with extremely different growth and obesity characteristics was generated to search for QTLs affecting serum concentrations of triglycerides (TG), total cholesterol (CHOL), HDL cholesterol (HDL-C), and LDL cholesterol (LDL-C). Compared with many other studies, we searched for spontaneous genetic variants contributing to high lipid levels under a standard breeding diet. Significant QTLs for CHOL were identified on chromosomes 4 and 6, and a female-specific locus on chromosome 3. QTLs for HDL-C were detected on chromosome 11 for both sexes, and on chromosome 1 for females. These QTLs are located in syntenic human regions that have QTLs that have not been previously confirmed in animal studies. LDL-C QTLs have been mapped for both sexes to chromosome 8 and in males on chromosome 13. Epistatic interactions that significantly accounted for the phenotypic variance of HDL-C, CHOL, and LDL-C serum concentrations were also detected with one interaction between chromosomes 8 and 15, accounting for 22% of the observed variance in LDL-C levels. The identified loci coincide in part with regions controlling growth and obesity. Thus, multiple genes or pleiotropic effects may be assumed. The identified QTLs for cholesterol and its transport proteins as subcomponents of risk for coronary heart disease will further improve our understanding of the genetic net controlling plasma lipid concentrations. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

Ein neues Bacteriochlorophyll aus Rhodospirillum rubrum

Zusammenfassung Rhodospirillum rubrum und Rhodopseudomonas palustris enthalten ein Bacteriochlorophyll, das mit Farnesol statt mit Phytol veretert ist. Das neue Bacteriochlorophyll (Bchl a_F) läßt sich vom bekannten Bacteriochlorophyll a (Bchl a_P) durch ¹H-NMR-Spektroskopie unterscheiden sowie durch Dünnschichtchromatographie der entsprechenden Phäophytine an mit Silbernitrat imprägniertem Kieselgel. Die Chromophore von Bchl a_F und Bchl a_P sind auch bezüglich ihrer Stereochemie identisch.

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A new bacteriochlorophyll from Rhodospirillum rubrum

Summary Rhodospirillum rubrum and Rhodopseudomonas palustris contain a bacteriochlorophyll which is a farnesyl rather than a phytyl ester. The new bacteriochlorophyll (Bchl a_F) can be distinguished from the well known bacteriochlorophyll a (Bchl a_P) by ¹H-n.m.r. spectroscopy and by t.l.c. of the corresponding pheophytins on silver nitrate impregnated silica gel. The chromophores of Bchl a_P and Bchl a_F are identical in structure and stereochemistry.

     

Age and Vascular Burden Determinants of Cortical Hemodynamics Underlying Verbal Fluency

Background

Aging processes and several vascular burden factors have been shown to increase the risk of dementia including Alzheimer''s disease. While pathological alterations in dementia precede diagnosis by many years, reorganization of brain processing might temporarily delay cognitive decline. We hypothesized that in healthy elderly individuals both age-related neural and vascular factors known to be related to the development of dementia impact functional cortical hemodynamics during increased cognitive demands.

Methods

Vascular burden factors and cortical functional hemodynamics during verbal fluency were assessed in 1052 non-demented elderly individuals (51 to 83 years; cross-sectional data of the longitudinal TREND study) using functional near-infrared spectroscopy (fNIRS). The prediction of functional hemodynamic responses by age in multiple regressions and the impact of single and cumulative vascular burden factors including hypertension, diabetes, obesity, smoking and atherosclerosis were investigated.

Results

Replicating and extending previous findings we could show that increasing age predicted functional hemodynamics to be increased in right prefrontal and bilateral parietal cortex, and decreased in bilateral inferior frontal junction during phonological fluency. Cumulative vascular burden factors, with hypertension in particular, decreased left inferior frontal junction hemodynamic responses during phonological fluency. However, age and vascular burden factors showed no statistical interaction on functional hemodynamics.

Conclusion

Based on these findings, one might hypothesize that increased fronto-parietal processing may represent age-related compensatory reorganization during increased cognitive demands. Vascular burden factors, such as hypertension, may contribute to regional cerebral hypoperfusion. These neural and vascular hemodynamic determinants should be investigated longitudinally and combined with other markers to advance the prediction of future cognitive decline and dementia.     

2’-5’寡聚腺苷酸合成酶（OAS）及其临床意义的研究进展

干扰素作用于靶细胞膜表面的受体后,通过信号转导系统诱导一系列抗病毒蛋白产生,干扰病毒复制以达到抗病毒目的。2’-5’寡聚腺苷酸合成酶（2’．5’oligoadenylatesynthetase,OAS）是干扰素作用于细胞后产生的一种重要的抗病毒蛋白,几十年来,国内外学者对OAS家族及其抗病毒机制进行了大量研究并取得了一定的进展,OAS被dsRNA激活后,催化生成2-5A,2-5A激活核酸内切酶RNaseL,降解病毒RNA,阻断病毒蛋白合成,从而发挥抗病毒作用。体内外研究表明,OAS的表达量或活性的变化可用于评价机体对干扰素的反应,反映干扰素抗病毒效果,另外,它还可作为系统性红斑狼疮的病情活动度的一种检测指标。因此,OAS具有重要的临床应用价值。本文就OAS家族及其抗病毒机制,其测定方法与对于病毒性肝炎和系统性红斑狼疮疾病的临床意义展开综述,以期对OAS的研究和应用提供参考。OAS是典型的干扰素诱导产物,可反映机体内干扰素的抗病毒水平,具有广阔的应用前景。