Modification of the Kedem-Katchalsky equations

The presented modification of the transport equations of Kedem-Katchalsky resulted in the introduction of (omega s/omega) and omega/(omega-Lp sigma[(1-sigma)C1-(1-sigma s)C2]) factors into the Kedem-Katchalsky equations. The above factors determine the influence of boundary layers on transport across the membrane. The modified Kedem-Katchalsky equations were verified for synthetic membranes and it was shown that the value of the (omega s/omega) factor depended on the type of membrane and the membrane configuration system. This modification facilitated a wider range of application of the Kedem-Katchalsky equations to systems in which the solutions were stirred or unstirred.     

Cholesterol conjugated oligonucleotide and LNA: A comparison of cellular and nuclear uptake by Hep2 cells enhanced by Streptolysin-O

Antisense and antigene oligonucleotides (ONs) are attractive drugs for gene therapy, but major limiting factors for their routine use are inefficient cellular uptake and low accessibility to the target sites. Adding various lipophilic conjugates to the ON improves intracellular delivery as has been previously reported.We studied the cellular delivery of various ON modifications, as well as their cytosolic and nuclear distribution in mammalian Hep2-EGFP-NLS cell line. We compared uptake efficacy of ON and LNA, both conjugated with cholesterol at the 5′ end. All ONs were 3′ labeled with fluorescent Cy5 dye. We made a comparison of the ONs uptake efficacy and the kinetics, both adding ONs to the culture medium, and using streptolysin-O (SL-O) permeabilization.The cellular uptake of each ON used in this study was visualized by fluorescent microscopy. We confirmed the results by FACS analysis. We determined the ratio between initial ON-chol concentration (0.4 μM) and the final amount in nucleus.SL-O can highly improve kinetics of ON delivery; not only into the cytoplasm but also to the nucleus, the presumed site of antigene ON action. The most effective nuclear uptake was observed when ON conjugated with cholesterol (ON-chol) and SL-O was used. Nuclear distribution of ON was reached within few minutes. In contrast, ON simply added to the medium reached cytoplasm only and the process of delivery took several hours. (Mol Cell Biochem 276: 61–69, 2005)     

Influence of psychosocial work-related factors on conventional risk factors of ischemic heart disease and homocysteine in Slovenian male workers

The influence of psychosocial work-related factors on the conventional risk factors of ischemic heart disease (IHD), particularly on the lipid changes and their effect on homocysteine is studied in this paper. Employed males aged 35 to 55 with angina pectoris or a myocardial infarction (IHD group) were compared to a group of individuals without ischemic heart disease (Control Group). Psychosocial factors were assessed using a Swedish Theorell questionnaire. The IHD Group was found to be at a higher risk of IHD due to higher work demands (OR = 1.25), worse job control (OR = 1.23), frequent smoking (OR = 2.2), leadership positions (OR = 3.97), higher BMI (p = 0.059) and higher levels of triglycerides (p = 0.005) and LDL-cholesterol (OR = 1.65). The level of HDL-cholesterol was significantly lower (1.0 vs. 1.4 mmol/L, p < 0.001, OR = 1.64), while the level of C-reactive protein (9.1 vs. 1.8 mg/L) and Interleukin-6 (6.5 vs. 1.6 ng/L) was higher. Homocysteine levels showed borderline significance (p = 0.056). Our study suggests a possible influence of psychosocial work-related factors on IHD risk factors, most of all on low HDL-cholesterol. No connection was found between psychosocial factors and the homocysteine level, shown to be an IHD risk factor at lower levels of approximately 10 micromol/L.     

<Superscript>13</Superscript>C-detected NMR experiments for measuring chemical shifts and coupling constants in nucleic acid bases

The paper presents a set of two-dimensional experiments that utilize direct ¹³C detection to provide proton–carbon, carbon–carbon and carbon–nitrogen correlations in the bases of nucleic acids. The set includes a ¹³C-detected proton–carbon correlation experiment for the measurement of ¹³C–¹³C couplings, the CaCb experiment for correlating two quaternary carbons, the HCaCb experiment for the ¹³C–¹³C correlations in cases where one of the carbons has a proton attached, the HCC-TOCSY experiment for correlating a proton with a network of coupled carbons, and a ¹³C-detected ¹³C–¹⁵N correlation experiment for detecting the nitrogen nuclei that cannot be detected via protons. The IPAP procedure is used for extracting the carbon–carbon couplings and/or carbon decoupling in the direct dimension, while the S³E procedure is preferred in the indirect dimension of the carbon–nitrogen experiment to obtain the value of the coupling constant. The experiments supply accurate values of ¹³C and ¹⁵N chemical shifts and carbon–carbon and carbon–nitrogen coupling constants. These values can help to reveal structural features of nucleic acids either directly or via induced changes when the sample is dissolved in oriented media. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Calcium Influx Rescues Adenylate Cyclase-Hemolysin from Rapid Cell Membrane Removal and Enables Phagocyte Permeabilization by Toxin Pores

Bordetella adenylate cyclase toxin-hemolysin (CyaA) penetrates the cytoplasmic membrane of phagocytes and employs two distinct conformers to exert its multiple activities. One conformer forms cation-selective pores that permeabilize phagocyte membrane for efflux of cytosolic potassium. The other conformer conducts extracellular calcium ions across cytoplasmic membrane of cells, relocates into lipid rafts, translocates the adenylate cyclase enzyme (AC) domain into cells and converts cytosolic ATP to cAMP. We show that the calcium-conducting activity of CyaA controls the path and kinetics of endocytic removal of toxin pores from phagocyte membrane. The enzymatically inactive but calcium-conducting CyaA-AC⁻ toxoid was endocytosed via a clathrin-dependent pathway. In contrast, a doubly mutated (E570K+E581P) toxoid, unable to conduct Ca²⁺ into cells, was rapidly internalized by membrane macropinocytosis, unless rescued by Ca²⁺ influx promoted in trans by ionomycin or intact toxoid. Moreover, a fully pore-forming CyaA-ΔAC hemolysin failed to permeabilize phagocytes, unless endocytic removal of its pores from cell membrane was decelerated through Ca²⁺ influx promoted by molecules locked in a Ca²⁺-conducting conformation by the 3D1 antibody. Inhibition of endocytosis also enabled the native B. pertussis-produced CyaA to induce lysis of J774A.1 macrophages at concentrations starting from 100 ng/ml. Hence, by mediating calcium influx into cells, the translocating conformer of CyaA controls the removal of bystander toxin pores from phagocyte membrane. This triggers a positive feedback loop of exacerbated cell permeabilization, where the efflux of cellular potassium yields further decreased toxin pore removal from cell membrane and this further enhances cell permeabilization and potassium efflux.     

Ultrastructure and genotypic characterization of the filamentous fungus Cochliobolus lunatus in comparison to the anamorphic strain Curvularia lunata

Abstract Although Curvularia lunata is classified as a conidial anamorph of Cochliobolus lunatus , the electron microscopic studies revealed the ultrastructure of both strains to be significantly different. C. lunatus m118 grows in the hyphal form characterized by a thick cell wall and numerous lipid bodies. C. lunata forms thinner hyphae of various sizes and large oval spores. Electrophoretic karyotypes of C. lunatus m118 (this paper) and C. lunata AT46 (Osiewacz, H. and Ridder, R. (1991) Curr. Genet. 20, 151–155) as well as RAPD-PCR analysis with the primer (GTG)₅ indicate close genetic relationship of both microorganisms.     

Trophic role of rotifers in the plankton of lake Kozjak (Plitvice Lakes)

The trophic role of rotifers in the zooplankton community of dimictic, oligotrophic lake Kozjak, the largest lake of the Plitvice Lakes, NW Dinarid Mountains, is analyzed. Their spatial and temporal biomass distribution in relation to that of protozoans, cladocerans and copepods shows that they form a significant part of the non-predatory zooplankton of this karstic standing water.     

An electrostatic steering mechanism of Cdc42 recognition by Wiskott-Aldrich syndrome proteins

The specific and rapid formation of protein complexes is essential for diverse cellular processes such as remodeling of actin filaments in response to the interaction between Rho GTPases and the Wiskott-Aldrich syndrome proteins (WASp and N-WASp). Although Cdc42, TC10, and other members of the Rho family have been implicated in binding to and activating the WAS proteins, the exact nature of such a protein-protein recognition process has remained obscure. Here, we describe a mechanism that ensures rapid and selective long-range Cdc42-WASp recognition. The crystal structure of TC10, together with mutational and bioinformatic analyses, proved that the basic region of WASp and two unique glutamates in Cdc42 generate favorable electrostatic steering forces that control the accelerated WASp-Cdc42 association reaction. This process is a prerequisite for WASp activation and a critical step in temporal regulation and integration of WASp-mediated cellular responses.