Insulin-dependent phosphatidylinositol 3-kinase/Akt and ERK signaling pathways inhibit TLR3-mediated human bronchial epithelial cell apoptosis

TLR3, one of the TLRs involved in the recognition of infectious pathogens for innate and adaptive immunity, primarily recognizes viral-associated dsRNA. Recognition of dsRNA byproducts released from apoptotic and necrotic cells is a recently proposed mechanism for the amplification of toxicity, suggesting a pivotal participation of TLR3 in viral infection, as well as in lung diseases where apoptosis plays a critical role, such as asthma and chronic obstructive pulmonary disease. In addition to metabolic control, insulin signaling was postulated to be protective by inhibiting apoptosis. Therefore, we explored the role of insulin signaling in protecting against TLR3-mediated apoptosis of human bronchial epithelial cells. Significant TLR3-mediated apoptosis was induced by polyinosinic-polycytidylic acid, a dsRNA analog, via caspase-8-dependent mechanisms. However, insulin efficiently inhibited TLR3/polyinosinic-polycytidylic acid-induced human bronchial epithelial cell apoptosis via PI3K/Akt and ERK pathways, at least in part, via upregulation of cellular FLIPs and through protein synthesis-independent mechanisms. These results indicate the significance of TLR3-mediated dsRNA-induced apoptosis in the pathogenesis of apoptosis-driven lung disease and provide evidence for a novel protective role of insulin.     

Identification of unprecedented purine-containing compounds, the zingerines, from ginger rhizomes (Zingiber officinale Roscoe) using a phase-trafficking approach

Three unprecedented purine-containing compounds, named [6]-, [8]-, and [10]-zingerines as they are 5-(6-amino-9H-purin-9-yl) analogs of [6]-, [8]-, and [10]-gingerols, respectively, were isolated from a methanolic extract of ginger rhizomes using a phase trafficking-based method that utilizes solid phase reagents allowing for fast and selective simultaneous separation of basic, acidic, and neutral components of natural products extracts.     

Cysteine metabolism-related genes and bacterial resistance to potassium tellurite

Tellurite exerts a deleterious effect on a number of small molecules containing sulfur moieties that have a recognized role in cellular oxidative stress. Because cysteine is involved in the biosynthesis of glutathione and other sulfur-containing compounds, we investigated the expression of Geobacillus stearothermophilus V cysteine-related genes cobA, cysK, and iscS and Escherichia coli cysteine regulon genes under conditions that included the addition of K₂TeO₃ to the culture medium. Results showed that cell tolerance to tellurite correlates with the expression level of the cysteine metabolic genes and that these genes are up-regulated when tellurite is present in the growth medium.     

Capillary electrophoresis for studying drug-DNA interactions

The development of new drugs to treat disease by binding directly to DNA offers much promise but is reliant on methods to determine the relative affinity of the putative drug for different DNA sequences. Such methods should ideally be rapid and inexpensive as well as reliable. Use of capillary electrophoresis in simple silica columns offers such a method. The development of systems in which the solvent carries a soluble polymer allows the reliable separation of DNA oligomers, of 12-20 bp in length, which can then be titrated with the ligand in competition experiments. The results obtained are comparable with those obtained by footprinting and give direct graphical output, easily analysed for relative binding affinity.     

Characterizing morphological (co)variation using structural equation models: Body size,allometric relationships and evolvability in a house sparrow metapopulation

Body size plays a key role in the ecology and evolution of all organisms. Therefore, quantifying the sources of morphological (co)variation, dependent and independent of body size, is of key importance when trying to understand and predict responses to selection. We combine structural equation modeling with quantitative genetics analyses to study morphological (co)variation in a meta‐population of house sparrows (Passer domesticus). As expected, we found evidence of a latent variable “body size,” causing genetic and environmental covariation between morphological traits. Estimates of conditional evolvability show that allometric relationships constrain the independent evolution of house sparrow morphology. We also found spatial differences in general body size and its allometric relationships. On islands where birds are more dispersive and mobile, individuals were smaller and had proportionally longer wings for their body size. Although on islands where sparrows are more sedentary and nest in dense colonies, individuals were larger and had proportionally longer tarsi for their body size. We corroborated these results using simulations and show that our analyses produce unbiased allometric slope estimates. This study highlights that in the short term allometric relationships may constrain phenotypic evolution, but that in the long term selection pressures can also shape allometric relationships.     

Statistical modeling of nitrogen-dependent modulation of root system architecture in Arabidopsis thaliana

Plant root development is strongly affected by nutrient availability. Despite the importance of structure and function of roots in nutrient acquisition,statistical modeling approaches to evaluate dynamic and temporal modulations of root system architecture in response to nutrient availability have remained as widely open and exploratory areas in root biology. In this study,we developed a statistical modeling approach to investigate modulations of root system architecture in response to nitrogen availability. Mathematical models were designed for quantitative assessment of root growth and root branching phenotypes and their dynamic relationships based on hierarchical con figuration of primary and lateral roots formulating the fishbone-shaped root system architecture in Arabidopsis thaliana. Time-series datasets reporting dynamic changes in root developmental traits on different nitrate or ammonium concentrations were generated for statistical analyses. Regression analyses unraveled key parameters associated with:(i) inhibition of primary root growth under nitrogen limitation or on ammonium;(ii) rapid progression of lateral root emergence in response to ammonium; and(iii) inhibition of lateral root elongation in the presence of excess nitrate or ammonium. This study provides a statistical framework for interpreting dynamic modulation of root system architecture,supported by metaanalysis of datasets displaying morphological responses of roots to diverse nitrogen supplies.     

Effects of carbohydrate accumulation on photosynthesis differ between sink and source leaves of Phaseolus vulgaris L

Accumulation of non-structural carbohydrate in leaves represses photosynthesis. However, the extent of repression should be different between sink leaves (sugar consumers) and source leaves (sugar exporters). We investigated the effects of carbohydrate accumulation on photosynthesis in the primary leaves of bean (Phaseolus vulgaris L.) during leaf expansion. To increase the carbohydrate content of the leaves, we supplied 20 mM sucrose solution to the roots for 5 d (sugar treatment). Plants supplied only with water and nutrients were used as controls. The carbohydrate contents, which are the sum of glucose, sucrose and starch, of the sugar-treated leaves were 1.5-3 times of those of the control leaves at all developmental stages. In the young sink leaves, the photosynthetic rate at saturating light and at an ambient CO2 concentration (A360) did not differ between the sugar-treated and control leaves. The A360 of sugar-treated source leaves gradually decreased relative to the control source leaves with leaf expansion. The initial slope of the A-Ci (CO2 concentration in the intercellular space) curve, and the Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) content per leaf area showed trends similar to that of A360. Differences in Amax between the treatments were slightly smaller than those in A360. These results indicate that the effect of carbohydrate accumulation on photosynthesis is significant in the source leaves, but not in the young sink leaves, and that the decrease in Rubisco content was the main cause of the carbohydrate repression of photosynthesis.     

A mast fruiting episode of the tropical tree Peltogyne purpurea (Caesalpinaceae) in the Osa Peninsula, Costa Rica

The existence of mast fruiting has not been well documented in the Neotropics. The occurrence of a mast fruiting episode in the population of the tree Peltogyne purpurea in the Osa Peninsula of Costa Rica is described. In February and March of 2000 most of the trees of this species produced a large fruit crop, compared with 1995-1999, when the number of fruit producing trees was very low or zero and those that did bear fruit, did so at a low intensity. In contrast, the fruit crop of 2000 was massive, all trees examined produced fruits and the intensity of fruiting was maximal. There is not enough information on the event for a hypothesis to be formed because the climatic or biological cues that triggered this sporadic flowering are unknown and there is no meteorological data available for this area. Populations with this mode of reproduction may experience local extinction bacause of logging operations.