Decreased cation channel activity and blunted channel-dependent eryptosis in neonatal erythrocytes

Eryptosis or apoptosis-like death of erythrocytes is characterized by phosphatidylserine exposure and erythrocyte shrinkage, both typical features of nucleated apoptotic cells. Eryptosis is triggered by activation of nonselective Ca²⁺-permeable cation channels with subsequent entry of Ca²⁺ and stimulation of Ca²⁺-sensitive scrambling of the cell membrane. The channels are activated and thus eryptosis is triggered by Cl^– removal, osmotic shock, oxidative stress, or glucose deprivation. The present study has been performed to compare cation channel activity and susceptibility to eryptosis in neonatal and adult erythrocytes. Channel activity was determined by patch-clamp analysis, cytosolic Ca²⁺ activity by fluo-3 fluorescence, phosphatidylserine exposure by FITC-labeled annexin V binding, and cell shrinkage by decrease in forward scatter in fluorescence-activated cell sorting analysis. Prostaglandin E₂ (PGE₂) formation, cation channel activity, Ca²⁺ entry, annexin V binding, and decreased forward scatter were triggered by removal of Cl^– in both adult and neonatal erythrocytes. The effects were, however, significantly blunted in neonatal erythrocytes. Osmotic shock, PGE_2, and platelet-activating factor similarly increased annexin V binding and decreased forward scatter, effects again significantly reduced in neonatal erythrocytes. On the other hand, spontaneous and oxidative (addition of tert-butylperoxide) stress-induced eryptosis was significantly larger in neonatal erythrocytes. In conclusion, cation channel activity, Ca²⁺ leakage, and thus channel-dependent triggering of eryptosis are blunted, whereas spontaneous and oxidative stress-induced eryptosis is more pronounced in neonatal erythrocytes. annexin V; osmotic cell shrinkage; calcium; apoptosis     

A novel aux/IAA28 signaling cascade activates GATA23-dependent specification of lateral root founder cell identity

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Highlights? GATA23 is involved in lateral root founder cell specification ? A coordinated migration of pericycle nuclei precedes the first asymmetric division ? An Aux/IAA28-dependent auxin signaling cascade controls GATA23 expression     

Excretion of endogenous boldione in human urine: Influence of phytosterol consumption

Boldenone (17-hydroxy-androsta-1,4-diene-3-one, Bol) and boldione (androst-1,4-diene-3,17-dione, ADD), are currently listed as exogenous anabolic steroids by the World Anti-Doping Agency. However, it has been reported that these analytes can be produced endogenously. Interestingly, only for Bol a comment is included in the list on its potential endogenous origin. In this study, the endogenous origin of ADD in human urine was investigated, and the potential influence of phytosterol consumption was evaluated.We carried out a 5-week in vivo trial with both men (n = 6) and women (n = 6) and measured α-boldenone, β-boldenone, boldione, androstenedione, β-testosterone and α-testosterone in their urine using gas chromatography coupled to multiple mass spectrometry (GC–MS–MS). The results demonstrate that endogenous ADD is sporadically produced at concentrations ranging from 0.751 ng mL⁻¹ to 1.73 ng mL⁻¹, whereas endogenous Bol could not be proven. We also tested the effect of the daily consumption of a commercially available phytosterol-enriched yogurt drink on the presence of these analytes in human urine. Results from this study could not indicate a relation of ADD-excretion with the consumption of phytosterols at the recommended dose. The correlations between ADD and other steroids were consistently stronger for volunteers consuming phytosterols (test) than for those refraining from phytosterol consumption (control). Excretion of AED, bT and aT did not appear to be dependent on the consumption of phytosterols.This preliminary in vivo trial indicates the endogenous origin of boldione or ADD in human urine, independent on the presence of any structural related analytes such as phytosterols.     

Human apolipoprotein E: polymorphism and binding domain of the receptors

This paper summarizes present knowledge of the LDL receptor-binding domain of apolipoprotein E, with special emphasis on the influence of apolipoprotein polymorphism on the interaction with apo B/E receptors.     

Quantity versus quality: identifying the most effective pollinators of the hummingbird-pollinated Vriesea rodigasiana (Bromeliaceae)

Although hummingbirds are considered the major bromeliad pollinators, different species may contribute differently to pollination. This study analyses the importance of different hummingbirds to pollination of Vriesea rodigasiana (Bromeliaceae), based on visitation frequency (a quantity component) and germinated pollen load per visit (a quality component) in the Atlantic rainforest of southeastern Brazil. This bromeliad flowers for 3–4 months with a peak in March. Its yellow, tubular flowers last about 13 h and demonstrate approach herkogamy. During flowering peak, Thalurania glaucopis visited more flowers than Ramphodon naevius, whereas by the end of the flowering season the latter visited more. Differences in hummingbird bill length resulted in different pollen placement and stigma contact. The short-billed T. glaucopis received pollen on the top of its head, depositing it on the center of the stigma, while the long-billed R. naevius received it on the proximal part of its bill, depositing it on the lower lobe of the stigma. Flowers visited by T. glaucopis had six times more pollen tubes than those visited by R. naevius. Our results suggest that this functional group of hummingbirds may be split into even smaller groups, namely short-billed and long-billed hummingbirds, based on different sites of pollen placement. Although both species were pollen vectors of V. rodigasiana, the short-billed T. glaucopis was its most effective pollinator in the area supporting Stebbin’s principle, linking floral features and good pollinators.     

Die niedermolekularen kohlenhydrate im cambialsaft von Larix decidua mill.

Zusammenfassung Die neutrale Fraktion der niedermolekularen Kohlenhydrate im Cambialsaft von Larix decidua ist untersucht worden. Fructose, Glucose, Saccharose, Coniferin, myo-Inositol und Sequoyitol konnten nachgewiesen und charakterisiert werden. Die Bedeutung der Cyclitole im Kohlenhydratstoffwechsel wird diskutiert.

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Low molecular weight carbohydrates in the cambial sap of Larix decidua mill.

Summary The neutral fraction of low molecular carbohydrates in the cambial sap of Larix decidua has been investigated. Fructose, glucose, saccharose, coniferin, myo-inositol, and sequoyitol have been isolated and characterised. The role of cyclitols in the carbohydrate metabolism is discussed.

     

Heteroaryl urea inhibitors of fatty acid amide hydrolase: Structure–mutagenicity relationships for arylamine metabolites

The structure–activity relationships for a series of heteroaryl urea inhibitors of fatty acid amide hydrolase (FAAH) are described. Members of this class of inhibitors have been shown to inactivate FAAH by covalent modification of an active site serine with subsequent release of an aromatic amine from the urea electrophile. Systematic Ames II testing guided the optimization of urea substituents by defining the structure–mutagenicity relationships for the released aromatic amine metabolites. Potent FAAH inhibitors were identified having heteroaryl amine leaving groups that were non-mutagenic in the Ames II assay.     

Improved age determination of blood and teeth samples using a selected set of DNA methylation markers

Age estimation from DNA methylation markers has seen an exponential growth of interest, not in the least from forensic scientists. The current published assays, however, can still be improved by lowering the number of markers in the assay and by providing more accurate models to predict chronological age. From the published literature we selected 4 age-associated genes (ASPA, PDE4C, ELOVL2, and EDARADD) and determined CpG methylation levels from 206 blood samples of both deceased and living individuals (age range: 0–91 years). This data was subsequently used to compare prediction accuracy with both linear and non-linear regression models. A quadratic regression model in which the methylation levels of ELOVL2 were squared showed the highest accuracy with a Mean Absolute Deviation (MAD) between chronological age and predicted age of 3.75 years and an adjusted R² of 0.95. No difference in accuracy was observed for samples obtained either from living and deceased individuals or between the 2 genders. In addition, 29 teeth from different individuals (age range: 19–70 years) were analyzed using the same set of markers resulting in a MAD of 4.86 years and an adjusted R² of 0.74. Cross validation of the results obtained from blood samples demonstrated the robustness and reproducibility of the assay. In conclusion, the set of 4 CpG DNA methylation markers is capable of producing highly accurate age predictions for blood samples from deceased and living individuals