The effects of cholesterol on the time-resolved emission anisotropy of 12-(9-anthroyloxy)stearic acid in dipalmitoylphosphatidylcholine bilayers

The time-resolved fluorescence emission anisotropy of 12-(9-anthroyloxy)stearic acid (12-AS) and 1,6-diphenyl-1,3,5-hexatriene (DPH) have been measured in dipalmitoylphosphatidylcholine liposomes in the presence and absence of 40 mol% cholesterol at temperatures above and below the phase transition temperature (41°C). By using a synchronously-pumped mode-locked frequency-doubled dye laser and single photon counting detection with an excitation response function of 300 picosecond, rotational correlation times down to less than 1 nanosecond could be resolved. Whereas DPH showed only small changes in the limiting anisotropy on the addition of cholesterol, 12-AS showed significant increases in this parameter with the effect being potentiated at higher temperatures. This difference in behaviour has been attributed to a fluorophore-cholesterol interaction that resulted in a change in the fluorophore geometry. Not only do DPH and 12-AS sense different depolarizing rotations due to the different directions of their emission dipoles but also differ in their lipid interactions which alter their limiting anisotropies. The implication is that the comparison of steady-state anisotropy measurements between chemically identical fluorophores in different lipid environments may be complicated by molecular distortions that change the motions to which the steady-state fluorescence parameters will be sensitive.     

Molecular packing of cholesterol in phospholipid vesicles as probed by dehydroergosterol

Ergosta-5,7,9,22-tetraen-3-β-ol (dehydroergosterol) was synthesized and employed as a probe of cholesterol behavior in phospholipid bilayers. Circular dichroism (CD) spectra were obtained. The CD of dehydroergosterol in sonicated egg phosphatidylcholine vesicles was dependent on cholesterol concentration, while in unsonicated egg phosphatidylcholine liposomes and in vesicles obtained by oxctylglucoside dialysis, the CD observed was independent of cholesterol content. The CD of dehydroergosterol in sonicated sphingomyelin vesicles exhibited a different dependence on cholesterol content than seen in sonicated egg phosphatidylcholine vesicles. These data are interpreted in terms of differences between the packing of cholesterol in systems of large and small radii of curvature and in different interactions between dehydroergosterol and phosphatidylcholine and sphingomyelin.     

Water-relation parameters of giant and normal cells of Capsicum annuum pericarp

Abstract. Measurements of the water-relation parameters of the giant subepidermal cells (volume, V = 0.119 to 1.658 mm³; = 0.53±0.35 mm³, SD, n = 23) and the smaller mesocarp parenchyma cells ( V = 0.10 to 0.79×10⁻³ mm³; = 0.36±0.27×10⁻³ mm³, SD, n = 6) of the inner pericarp surface of Capsicum annuum L. were made using the Jülich pressure probe. The volumetric elastic modulus ɛ for the large cells was between 1.5 and 27 MPa for a pressure range of 0.09 to 0.41 MPa. For the small cells ɛ was 0.1 to 0.6 MPa for a pressure range of 0.22 to 0.39 MPa. The turgor pressure P , the half-time of water exchange T _1/2, and the hydraulic conductivity L _p were as follows, with SD and number of replicates: large cells, P = 0.27±0.06 MPa (23), T _1/2=2.7±2.2 s (46), L _p=5.8±3.7 pm s⁻¹ Pa⁻ (46); small cells, P = 0.33±0.07 MPa (6), T _1/2= 33±10s (12), L _p=0.21±0.07 pm s⁻¹ Pa⁻¹ (12). The determination of these basic water-relation parameters is considered as a prerequisite for future ecotoxicological and phytopathological studies. The differences between the large and the small cells are discussed in relation to a desirable biophysical definition of succulence. Further, for the large cells a pressure and volume dependence of ɛ was demonstrated.     

牛泌乳素mRNA的分离及鉴定

本文报道了从牛脑垂体提取总RNA,经寡聚脱氧胸苷纤维素亲合层析分离获得牛脑垂体Poly(A)~+RNA。牛泌乳素mRNA经含羟甲基汞琼脂糖凝胶电泳分析,估计其长度约为1200个核苷酸。根据牛泌乳素的部分氨基酸序列推断并合成寡聚核苷酸探针,经Northern印迹杂交及放射自显影分析,证实了该mRNA中含有牛泌乳素mRNA的序列。在兔网织红细胞体外翻译体系中,牛泌乳素mRNA促进了~35S-甲硫氨酸参入,翻译合成的初级翻译产物能与兔抗羊PRL抗血清发生特异性免疫沉淀反应,SDS聚丙烯酰胺凝胶电泳及放射自显影分析结果表明,牛泌乳素前体的分子量约25000。     

Turgor pressure and water transport properties of suspension-cultured cells of Chenopodium rubrum L.

The turgor pressure and water relation parameters were determined in single photoautotrophically grown suspension cells and in individual cells of intact leaves of Chenopodium rubrum using the miniaturized pressure probe. The stationary turgor pressure in suspension-cultured cells was in the range of betwen 3 and 5 bar. From the turgor pressure relaxation process, induced either hydrostatically (by means of the pressure probe) or osmotically, the halftime of water exchange was estimated to be 20±10 s. No polarity was observed for both ex- and endosmotic water flow. The volumetric elastic modulus, , determined from measurements of turgor pressure changes, and the corresponding changes in the fractional cell volume was determined to be in the range of between 20 and 50 bar. increases with increasing turgor pressure as observed for other higher plant and algal cells. The hydraulic conductivity, Lp, is calculated to be about 0,5–2·10^–6 cm s^–1 bar^–1. Similar results were obtained for individual leaf cells of Ch. rubrum. Suspension cells immobilized in a cross-linked matrix of alginate (6 to 8% w/w) revealed the same values for the half-time of water exchange and for the hydraulic conductivity, Lp, provided that the turgor pressure relaxation process was generated hydrostatically by means of the pressure probe. Thus, it can be concluded that the unstirred layer from the immobilized matrix has no effect on the calculation of Lp from the turgor pressure relaxation process, using the water transport equation derived for a single cell surrounded by a large external volume. By analogy, this also holds true for Lp-values derived from turgor pressure changes generated by the pressure probe in a single cell within the leaf tissue. The fair similarity between the Lp-values measured in mesophyll cells in situ and mesophyll-like suspension cells suggests that the water transport relations of a cell within a leaf are not fundamentally different from those measured in a single cell.     

Interaction of DDT (1,1,1-trichloro-2,2-BIS(p-chlorophenyl)-ethane with liposomal phospholipids

The influence of $\text{1,1,1-}\text{trichloro}\text{-2,2-}\text{bis}\text{(p-}\text{chlorophenyl}\text{)}\text{ethane}$ (DDT) and several other pesticides on the physical state of membrane phospholipids was investigated using model lipids. The thermal dependence of fluorescence intensity of the probe parinaric acid in dipalmitoylphosphatidylcholine liposomes and lipid vesicles of mixed composition were recorded. DDT was incorporated into the liposomal bilayer. The insecticide lowered the phase transition temperature and broadened the temperature range of the transition. The effects were concentration-dependent.The results may be interpreted as a sort of blurred and facilitated phase transition of bilayer lipids caused by intercalation of DDT between fatty acyl chains of membrane phospholipids.     

A combined scanning and transmission electron microscopic study and electron probe microanalysis of human pineal acervuli

Summary Untreated, decalcified and trypsinized acervuli from human pineal bodies were studied with the scanning and transmission electron microscope as well as by electron probe microanalysis. The mulberry-like acervuli are composed of a various number of spherical lobes (135–800 m) between which clustered groups of globuli (4–14 urn in diameter) are observed. The acervular lobes are very probably formed by an aggregation of these globuli. Small round particles 125–500 Å in diameter are observed on the surface of the pineal concretions. These are not influenced by either decalcification or trypsin treatment. The acervular mineral corresponds morphologically to hydroxyapatite. The electron probe microanalysis reveals the existence of calcium and phosphorus as main components of the acervuli. Small quantities of magnesium and strontium were also detected.Dedicated to Professor Berta Scharrer on the occasion of her 70th birthdayWith the technical assistance of Mr. P.A. MilliquetThe author wishes to thank Mr. Bauer and Mr. Fryder (Nestec SA, La Tour de Peilz) for the use of the Cambridge Stereoscan electron microscope and Dr. T. Jalanti (C.M.E., Lausanne) for his help with the use of the X-ray microanalyser     

A BUNCH-OLIGONUCLEOTIDE FORMING STABLE MONOMOLECULAR QUADRUPLEX CONTAINING A T-TETRAD

The chemical synthesis of bunch-ODN I and II prone to form quadruplex structures containing G-and T-tetrads has been reported. Structural studies were performed by ¹H-NMR and CD melting experiments.     

A CONVENIENT METHOD FOR THE SYNTHESIS OF OLIGONUCLEOTIDE-CATIONIC PEPTIDE CONJUGATES

A method was developed for the synthesis of oligonucleotide-cationic peptide conjugates in solution phase by disulfide bond formation. Precipitation was avoided by the easily removable triethylammonium trifluoroacetate (TEATFAc) salt which served at the same time as a buffer of the reaction mixture. The fast and high yielding disulfide bond formation was due to the Npys thio protecting and activating group of Cys. A solution of the free 5′-thiol modified oligonucleotide obtained from Poly-Pak? purification was used for conjugation.     

Bladder tissue characterization using probe‐based Raman spectroscopy: Evaluation of tissue heterogeneity and influence on the model prediction

Existing approaches for early‐stage bladder tumor diagnosis largely depend on invasive and time‐consuming procedures, resulting in hospitalization, bleeding, bladder perforation, infection and other health risks for the patient. The reduction of current risk factors, while maintaining or even improving the diagnostic precision, is an underlying factor in clinical instrumentation research. For example, for clinic surveillance of patients with a history of noninvasive bladder tumors real‐time tumor diagnosis can enable immediate laser‐based removal of tumors using flexible cystoscopes in the outpatient clinic. Therefore, novel diagnostic modalities are required that can provide real‐time in vivo tumor diagnosis. Raman spectroscopy provides biochemical information of tissue samples ex vivo and in vivo and without the need for complicated sample preparation and staining procedures. For the past decade there has been a rise in applications to diagnose and characterize early cancer in different organs, such as in head and neck, colon and stomach, but also different pathologies, for example, inflammation and atherosclerotic plaques. Bladder pathology has also been studied but only with little attention to aspects that can influence the diagnosis, such as tissue heterogeneity, data preprocessing and model development. The present study presents a clinical investigative study on bladder biopsies to characterize the tumor grading ex vivo, using a compact fiber probe‐based imaging Raman system, as a crucial step towards in vivo Raman endoscopy. Furthermore, this study presents an evaluation of the tissue heterogeneity of highly fluorescent bladder tissues, and the multivariate statistical analysis for discrimination between nontumor tissue, and low‐ and high‐grade tumor.