The N-Terminus of Apolipoprotein A-V Adopts a Helix-Bundle Molecular Architecture

Previous studies of recombinant full-length human apolipoprotein A-V (apoA-V) provided evidence of the presence of two independently folded structural domains. Computer-assisted sequence analysis and limited proteolysis studies identified an N-terminal fragment as a candidate for one of the domains. C-Terminal truncation variants in this size range, apoA-V(1-146) and apoA-V(1-169), were expressed in Escherichia coli and isolated. Unlike full-length apoA-V or apoA-V(1-169), apoA-V(1-146) was soluble in neutral-pH buffer in the absence of lipid. Sedimentation equilibrium analysis yielded a weight-average molecular weight of 18811, indicating apoA-V(1-146) exists as a monomer in solution. Guanidine HCl denaturation experiments at pH 3.0 yielded a one-step native to unfolded transition that corresponds directly with the more stable component of the two-stage denaturation profile exhibited by full-length apoA-V. On the other hand, denaturation experiments conducted at pH 7.0 revealed a less stable structure. In a manner similar to that of known helix bundle apolipoproteins, apoA-V(1-146) induced a relatively small enhancement in 8-anilino-1-naphthalenesulfonic acid fluorescence intensity. Quenching studies with single-Trp apoA-V(1-146) variants revealed that a unique site predicted to reside on the nonpolar face of an amphipathic R-helix was protected from quenching by KI. Taken together, the data suggest the 146 N-terminal residues of human apoA-V adopt a helix bundle molecular architecture in the absence of lipid and, thus, likely exist as an independently folded structural domain within the context of the intact protein

A shortcut to identifying small molecule signals that regulate behavior and development in Caenorhabditis elegans

Small molecule metabolites play important roles in Caenorhabditis elegans biology, but effective approaches for identifying their chemical structures are lacking. Recent studies revealed that a family of glycosides, the ascarosides, differentially regulate C. elegans development and behavior. Low concentrations of ascarosides attract males and thus appear to be part of the C. elegans sex pheromone, whereas higher concentrations induce developmental arrest at the dauer stage, an alternative, nonaging larval stage. The ascarosides act synergistically, which presented challenges for their identification via traditional activity-guided fractionation. As a result the chemical characterization of the dauer and male attracting pheromones remained incomplete. Here, we describe the identification of several additional pheromone components by using a recently developed NMR-spectroscopic approach, differential analysis by 2D NMR spectroscopy (DANS), which simplifies linking small molecule metabolites with their biological function. DANS-based comparison of wild-type C. elegans and a signaling-deficient mutant, daf-22, enabled identification of 3 known and 4 previously undescribed ascarosides, including a compound that features a p-aminobenzoic acid subunit. Biological testing of synthetic samples of these compounds revealed additional evidence for synergy and provided insights into structure–activity relationships. Using a combination of the three most active ascarosides allowed full reconstitution of the male-attracting activity of wild-type pheromone extract. Our results highlight the efficacy of DANS as a method for identifying small-molecule metabolites and placing them within a specific genetic context. This study further supports the hypothesis that ascarosides represent a structurally diverse set of nematode signaling molecules regulating major life history traits

Uso de nanodiscos de anfotericina B (AMB-NDs) para el tratamiento de enfermedades fúngicas en plantas

III Encuentro sobre Nanociencia y Nanotecnología de Investigadores y Tecnólogos Andaluce

HIF- and Non-HIF-Regulated Hypoxic Responses Require the Estrogen-Related Receptor in Drosophila melanogaster

Low-oxygen tolerance is supported by an adaptive response that includes a coordinate shift in metabolism and the activation of a transcriptional program that is driven by the hypoxia-inducible factor (HIF) pathway. The precise contribution of HIF-1a in the adaptive response, however, has not been determined. Here, we investigate how HIF influences hypoxic adaptation throughout Drosophila melanogaster development. We find that hypoxic-induced transcriptional changes are comprised of HIF-dependent and HIF-independent pathways that are distinct and separable. We show that normoxic set-points of carbohydrate metabolites are significantly altered in sima mutants and that these animals are unable to mobilize glycogen in hypoxia. Furthermore, we find that the estrogen-related receptor (dERR), which is a global regulator of aerobic glycolysis in larvae, is required for a competent hypoxic response. dERR binds to dHIFa and participates in the HIF-dependent transcriptional program in hypoxia. In addition, dERR acts in the absence of dHIFa in hypoxia and a significant portion of HIF-independent transcriptional responses can be attributed to dERR actions, including upregulation of glycolytic transcripts. These results indicate that competent hypoxic responses arise from complex interactions between HIF-dependent and -independent mechanisms, and that dERR plays a central role in both of these programs

Digestibility of Common Forage Plants and Energetic Requirements of the Black-Tailed Prairie Dog

Black-tailed prairie dogs (Cynomys ludovicianus) assimilated 51.5 percent of the wheatgrass (Agropyron intermedium) they consumed; thus, they would have to consume 0.148 kcal · g-1 · day-l in order to obtain the 0.076 kcal · g-1 · day-1 they would require to maintain their weight. Prairie dogs assimilated 31.5 percent of the buffalograss/blue grama mixture (Buchloe dactyloides/Bouteloua gracilis) they were fed. They would have to consume 0.229 kcal · g-1 · day-1 of this forage to assimilate 0.072 kcal · g-1 · day-1 and maintain their weight. The proximate composition of forages fed in feeding trials was similar to that found for those collected on the study area. Total digestible nutrients (TON) for wheatgrass in feeding trials and from the study site averaged 46.7 percent and 45.5 percent, respectively. The mean TON for buffalograss/blue grama feeding trial and study area forages were 26.4 percent and 23 percent, respectively. The assimilation efficiency (AE) of prairie dogs on their natural diet of 34 percent forbs and 65 percent grasses was 71.8 percent. The higher AE in the wild population than in captive animals fed grasses is due to the presence of highly digestible forbs. The estimated Resting Metabolic Rate (RMR) of 0.056 kcal · g-1 day-l is relatively low; 85 percent of the Basal Metabolic Rate as predicted by a metabolic body size formula. The energy cost of activity is the primary cause for the difference in RMR estimates from oxygen consumption tests and caloric requirements found in feeding trials. The prairie dog feeding trial results were 1.32 times greater than the RMR estimates

Drug Cartels and Government in Mexico: A Replication and Extension

This paper analyzes the relationship between drug cartels and the government in Mexico. It also seeks to determine the reasons for an upsurge of violence and cartel related murders in Mexico

Fear as a predictor of firearm ownership and concealed weapons permits in Clark County, Nevada

This study is specific to Clark County, Nevada. Two relationships, the relationship between fear and gun possession [defined in terms of firearms registration] and the relationship between fear and the issuance of concealed weapons permits, were posited. Data for the number of registered firearms and issued concealed weapons permits were obtained from the Las Vegas Metropolitan Police Department Firearms Detail and CCW Detail. Criminal incidents involving firearms in public areas that appeared to be random in nature [stranger to stranger violence] were gathered through an archive search of Nevada\u27s largest newspaper servicing Clark County, the Las Vegas Review-Journal; Statistical analysis established that there is no significant relationship between fear and firearms possession, as well as no relationship between fear and the issuance of concealed weapons permits. When assessing the impact of particularly tragic incidents and controlling for seasonal trends, however, a significant relationship between fear and gun ownership does emerge. The relationship between fear and concealed weapons permits remains insignificant, even with these added controls