Genetic differentiation of the Euglossini (Hymenoptera, Apidae) populations on a mainland coastal plain and an island in southeastern Brazil

Euglossini bees are among the main pollinators of plant species in tropical and subtropical forests in Central and South America. These bees are known as long-distance pollinators due to their exceptional flight performance. Here we assessed through microsatellite loci the gene variation and genetic differentiation between populations of four abundant Euglossini species populations sampled in two areas, Picinguaba (mainland) and Anchieta Island, Ubatuba, São Paulo State, southeastern Brazil. There was no significant genetic differentiation between the island and mainland samples of Euglossa cordata (Fst = 0.008, P = 0.60), Eulaema cingulata (Fst = 0.029, P = 0.29) and Eulaema nigrita (Fst = 0.062, P = 0.38), but a significant gene differentiation between mainland and island samples of Euglossa stellfeldi (Fst = 0.028, P = 0.016) was detected. As expected, our results showed that the water body that separates the island from the mainland does not constitute a geographic barrier for these Euglossini bees. The absence of populational structuring of three out the four species studied corroborates previous reports on those bees, characterized by large populations, with high gene diversity and gene flow and very low levels of diploid males. But the Eg. stellfeldi results clearly point that dispersal ability is not similar to all euglossine bees, what requires the development of different conservationist strategies to the Euglossini species.     

Dual on-off and off-on switchable oligoaziridine biosensor

A water-soluble biocompatible aziridine-based biosensor with pendant anthracene units was synthesized by radicalar polymerization of N-substituted aziridines in supercritical carbon dioxide. The binding ability of the sensor towards a series of metal ions was examined by comparing the fluorescence intensities of the solutions before and after the addition of 100 equivalents of a solution of the metal ion chloride salt. A fast, simple and highly optical sensitive dual behavior, "off-on" and "on-off" response, was observed after the biosensor was exposed to the metal cations in aqueous solution. Zinc presented the highest fluorescence enhancement (turn-on) and copper presented the highest fluorescence quenching (turn-off). The response time was found to be instantaneous and the detection limit was achieved even in the presence of excess metal cation competitors. By using immunofluorescence microscopy it was also shown that oligoaziridine acts as an "on-off" probe through highly sensitive (detection limit of 1.6nM), selective and reversible binding to copper anions under physiologic conditions using living Human Fibroblast cells. The stoichiometry for the reaction of the biosensor with Cu(2+) was determined by a Job plot and indicates the formation of an oligoaziridine-Cu(2+) 1:2 adduct.     

The role of l-arginine-nitric oxide pathway in bacterial translocation

This study investigated the nitric oxide (NO) role as a mediator of arginine on bacterial translocation (BT) and gut damage in mice after intestinal obstruction (IO). The effects of pretreatment with arginine with or without NO inhibition on the systemic and local immunological response were also assessed. Mice were categorized into four groups. Group ARG received chow containing 2 % arginine, while group ARG + l-NAME received the same diet plus l-NAME (N-nitro-l-arginine methyl ester) by gavage. The IO and Sham groups were fed standard chow. After 7 days, animals were gavaged with radiolabeled Escherichia coli, anesthetized and subjected to IO, except the Sham group. Animals were euthanized after 18 h, and BT was evaluated in the mesenteric lymph nodes, blood, liver, spleen and lungs. In another experiment, the intestinal injury was assessed regarding intestinal permeability and ileum histological analyses. Intestinal secretory immunoglobulin A (sIgA) levels, serum IFN-γ and IL-10 cytokines were assessed. Arginine reduced BT, but NO inhibition enhanced BT compared with the ARG group (p < 0.05). Intestinal permeability in the ARG and ARG + l-NAME groups was similar but decreased when compared with the IO group (p < 0.05). Histological preservation was observed. Arginine treatment increased IL-10 and sIgA levels when compared with the Sham and IO groups (p < 0.05). The cytokines and sIgA concentrations were similar in the ARG + l-NAME and Sham groups. Arginine appeared to reduce BT and its effects on the modulation of cytokines and secretory IgA in mice after IO are mediated by NO production.     

A Conserved Interaction between a C-Terminal Motif in Norovirus VPg and the HEAT-1 Domain of eIF4G Is Essential for Translation Initiation

Translation initiation is a critical early step in the replication cycle of the positive-sense, single-stranded RNA genome of noroviruses, a major cause of gastroenteritis in humans. Norovirus RNA, which has neither a 5´ m⁷G cap nor an internal ribosome entry site (IRES), adopts an unusual mechanism to initiate protein synthesis that relies on interactions between the VPg protein covalently attached to the 5´-end of the viral RNA and eukaryotic initiation factors (eIFs) in the host cell. For murine norovirus (MNV) we previously showed that VPg binds to the middle fragment of eIF4G (4GM; residues 652–1132). Here we have used pull-down assays, fluorescence anisotropy, and isothermal titration calorimetry (ITC) to demonstrate that a stretch of ~20 amino acids at the C terminus of MNV VPg mediates direct and specific binding to the HEAT-1 domain within the 4GM fragment of eIF4G. Our analysis further reveals that the MNV C terminus binds to eIF4G HEAT-1 via a motif that is conserved in all known noroviruses. Fine mutagenic mapping suggests that the MNV VPg C terminus may interact with eIF4G in a helical conformation. NMR spectroscopy was used to define the VPg binding site on eIF4G HEAT-1, which was confirmed by mutagenesis and binding assays. We have found that this site is non-overlapping with the binding site for eIF4A on eIF4G HEAT-1 by demonstrating that norovirus VPg can form ternary VPg-eIF4G-eIF4A complexes. The functional significance of the VPg-eIF4G interaction was shown by the ability of fusion proteins containing the C-terminal peptide of MNV VPg to inhibit in vitro translation of norovirus RNA but not cap- or IRES-dependent translation. These observations define important structural details of a functional interaction between norovirus VPg and eIF4G and reveal a binding interface that might be exploited as a target for antiviral therapy.     

Stress responses of the sea cucumber Holothuria forskali during aquaculture handling and transportation

Animal welfare during handling and transportation to aquaculture facilities or public aquaria is commonly estimated by addressing injury and mortality levels. Although these procedures have been optimized for different species, data on individual species’ cellular capabilities to tolerate stress are still scarce. In the present study, several biomarkers related with oxidative stress and energy metabolism were assessed in Holothuria forskali during animal acclimation, pre-transport, transport and quarantine. Combined analyses confirmed that sea cucumbers experienced high oxidative stress during transport, but had the capability to deal with it using a complex of cellular defence mechanisms, which enabled recovery from oxidative stress without permanent damage. Through a better understanding of individual species and the development of optimal parameters, this approach has the potential to improve animal wellbeing during and after acclimation, transportation and recovery processes.     

Age,growth, and reproductive biology of the Atlantic spadefish Chaetodipterus faber in southern Brazil

Ichthyological Research - This is the first study to investigate the age, growth and reproductive biology of the Atlantic spadefish Chaetodipterus faber in southern Brazil. A total of 625...