Advanced glycation end-products disrupt human endothelial cells redox homeostasis: new insights into reactive oxygen species production

Advanced glycation end-products (AGEs) trigger multiple metabolic disorders in the vessel wall that may in turn lead to endothelial dysfunction. The molecular mechanisms by which AGEs generate these effects are not completely understood. Oxidative stress plays a key role in the development of deleterious effects that occur in endothelium during diabetes. Our main objectives were to further understand how AGEs contribute to reactive oxygen species (ROS) overproduction in endothelial cells and to evaluate the protective effect of an antioxidant plant extract. The human endothelial cell line EA.hy926 was treated with native or modified bovine serum albumin (respectively BSA and BSA-AGEs). To monitor free radicals formation, we used H₂DCF-DA, dihydroethidium (DHE), DAF-FM-DA and MitoSOX Red dyes. To investigate potential sources of ROS, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and mitochondrial inhibitors were used. The regulation of different types of ROS by the polyphenol-rich extract from the medicinal plant Doratoxylon apetalum was also studied for a therapeutic perspective. BSA-AGEs exhibited not only less antioxidant properties than BSA, but also pro-oxidant effects. The degree of albumin glycoxidation directly influenced oxidative stress through a possible communication between NADPH oxidase and mitochondria. D. apetalum significantly decreased intracellular hydrogen peroxide and superoxide anions mainly detected by H₂DCF-DA and DHE respectively. Our results suggest that BSA-AGEs promote a marked oxidative stress mediated at least by NADPH oxidase and mitochondria. D. apetalum plant extract appeared to be an effective antioxidant compound to protect endothelial cells.     

Korallipteris,a new genus for Mesozoic Gleichenia-like fern fronds

A new morphogenus, Korallipteris, is proposed to accommodate fertile or sterile fern fronds possessing essentially Gleichenia-like morphology (e.g., pinnate fronds with small pecopteroid pinnules) but lacking diagnostic features that allow their classification at fern family-level. The aim is thus, to solve an old nomenclatural problem that involves the use of illegitimate genera, such as Gleichenites Goeppert and Microphyllopteris Arber. Several species of Gleichenites described from the Mesozoic of Argentina and Chile, and Microphyllopteris unisora Cantrill and Nagalingum from Antarctica are here reassigned to Korallipteris gen. nov. The proposal of Nagalingum and Cantrill to preserve Gleicheniaceaephyllum Crabtree emend. Nagalingum and Cantrill for true Gleicheniaceous ferns, diagnosed by having an arrested laminar bud, is here accepted.     

Biological and environmental effects on fine-scale seed dispersal of an invasive tree in a secondary subtropical forest

Dispersal abilities of invading species emerge from the interaction between the species and some features of the target community. Ligustrum lucidum is a tree species invading different ecosystems. Major spatial patterns of Ligustrum invasions and their ecological consequences have been analyzed, but no study addressed the dispersal process at a fine scale, assessing the effects of different biological and environmental factors. Ligustrum lucidum is an ornithochoric species. The structure of the environment determines bird movements and thus affects seed dispersal. We used inverse modeling to analyze bird-mediated dispersal of L. lucidum seeds in a secondary Yungas forest and surrounding crop-fields. We assessed the effects of egestion mode (regurgitation and defecation) and tree density (as an environment character) on seed dispersal. Seed dispersal presented different spatial patterns depending on the egestion mode. Tree density was positively associated with the number of regurgitated dispersed seeds and negatively associated with the number of defecated dispersed seeds. In both cases, dispersal distance increased in open areas, but absence of perches inhibited seed arrival. Thus, spread of L. lucidum is facilitated in open areas with some trees; inside the native forest, short distance dispersal facilitates the gradual invasion by this exotic species. Our results suggest that processes like crop abandonment and forest succession, which are active in subtropical montane systems, may facilitate L. lucidum invasion. Our seed dispersal models should be combined with actual distribution maps of L. lucidum to identify areas vulnerable to new invasions.     

On the mechanism of formation and spectral properties of radical anions generated by the reduction of -[Re(CO)3(5-nitro-1,10-phenanthroline)] and -[Re(CO)3(3,4,7,8-tetramethyl-1,10-phenanthroline)] pendants in poly-4-vinylpyridine polymers

The electrochemical reduction in aprotic media of -[Re^I(CO)₃L]⁺ pendants in poly-4-vinylpyridine polymers is compared to that of [Re^I(CO)₃L]⁺ complexes (L = 5-nitro-1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline). The UV-Vis absorption spectra of the reduced radical anions of 5-nitro-1,10-phenanthroline (NO₂-phen) and 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) were obtained by spectro-electrochemistry of [Re^I(CO)₃(NO₂-phen)(CH₃CN)]⁺ and [Re^I(CO)₃(tmphen)(CH₃CN)]⁺, respectively. Similar spectra were obtained for the radical anions -phen and tmphen⁻ after pulse radiolysis experiments with -[Re^I(CO)₃L]⁺-containing polymers. The analysis of the time-resolved difference spectra was performed using “multivariate curve resolution” (MCR) techniques. Unlike , CH₂OH radicals were unable to reduce tmphen ligands. The reaction of and/or CH₂OH with -[Re^I(CO)₃(NO₂-phen)]⁺-containing polymers generates -[Re^I(CO)₃(-phen)] pendants which after disproportionation give rise to products with λ_max = 380 nm. The kinetic behavior of -[Re^I(CO)₃(-phen)] pendants under different experimental conditions is discussed.     

CD63 is not required for production of infectious human immunodeficiency virus type 1 in human macrophages

During the assembly of human immunodeficiency virus type 1 (HIV-1) particles, the tetraspanin CD63 can be incorporated into the viral membrane. Indeed, cell surface tetraspanin microdomains that include CD63 have been proposed as sites for virus release. In addition, antibodies against CD63 can inhibit HIV infection of macrophages. In this cell type, HIV assembles into intracellularly sequestered plasma membrane domains that contain several other tetraspanins, including CD81, CD9, and CD53. CD63 is recruited to this domain following HIV infection. Together, these observations suggest that CD63 may have some function in the assembly of infectious virus particles and/or the infectivity of assembled virions. Here we have used RNA interference to knock down CD63 expression in monocyte-derived primary macrophages. We show that in the absence of CD63, HIV assembly is quantitatively comparable to that seen in CD63-expressing macrophages and that virus assembly occurs on compartments positive for CD81, CD9, and CD53. Moreover, the infectivity of macrophage-derived virus is unaffected by the loss of CD63. Together, our results indicate that at least in tissue culture, CD63 expression is not required for either the production or the infectivity of HIV-1.     

Glutamate synthase in greening callus of Bouvardia ternifolia Schlecht

The distribution of the two glutamate-synthase (GOGAT) activities known to exist in higher plants (NADH dependent, EC 2.6.1.53; and ferredoxin dependent, EC 1.4.7.1) was studied in non-chlorophyllous and chlorophyllous cultured tissue as well as in young leaves of Bouvardia ternifolia. The NADH-GOGAT was present in all three tissues. Using a sucrose gradient we found it in both the soluble and the plastid fraction of non-chlorophyllous and chlorophyllous tissue, but exclusively in the chloroplast fraction of the leaves. Ferredoxin-GOGAT was found only in green tissues and was confined to the chloroplasts. Ferredoxin-GOGAT activity increased in parallel with the chlorophyll content of the callus during the greening process in Murashige-Skoog medium (nitrate and ammonium as the nitrogen sources), while NADH-GOGAT was not affected by the greening process in this medium. Furthermore, both activities were differentially affected by either nitrate or ammonium as the sole nitrogen source in the medium during this process. It is suggested that each GOGAT activity is a different entity or is differently regulated.Abbreviations GOGAT glutamate synthase - MS Murashige-Skoog (1962) medium - PMSF phenylmethylsulfonyl fluoride     

Influence of the hydromechanical stress and temperature on growth and antibody fragment production with <Emphasis Type="Italic">Bacillus megaterium</Emphasis>

Bacillus megaterium was used for production of the lysozyme-specific recombinant scFv D1.3 antibody fragment. Key process parameters like the temperature and the hydromechanical stress play a very important role for significant product formation during process development or scale-up. In this study, the influence of these two variables on growth and recombinant antibody fragment production in a 2-L lab-scale bioreactor system was investigated using a central composite design. Especially a significant influence of the hydromechanical stress on antibody fragment production was detected in batch cultivations. While volumetric power inputs of about 0.5 kW/m³ (agitation rates around 500 min⁻¹) are usually employed in batch cultivations, in this work maximal product concentration was found at a volumetric power input of about 0.06 kW/m³ (agitation rate around 250 min⁻¹) and at a high cultivation temperature of 41 °C. The influence of the two process variables at single-cell level was estimated using flow cytometry too. The characterization was done by estimating the membrane potential giving a hint on bioprocess productivity and secretion capability: the best production was obtained through big cells with low specific membrane potential, which grew at low volumetric power inputs and high cultivation temperatures.