Genetic characterization of fall armyworm (Lepidoptera: Noctuidae) host strains in Argentina

Fall armyworm is a major economic pest throughout the Western Hemisphere. Previous studies of populations in the southern United States, Brazil, and the Caribbean demonstrated the existence of two morphologically identical but genetically distinct host strains that can only be distinguished using genetic markers, including polymorphisms in the mitochondrial Cytochrome Oxidase I (COI) gene and in the Z-chromosome linked Triose phosphate isomerase (Tpi) gene. The strains differ in some physiological and behavioral characteristics, most notably their preference for different plant hosts, but are capable of hybridizing in the laboratory and in the field. These traits suggest that the strains are in the process of divergence, which may or may not be hemispheric in scope. The objective of this study was to determine whether the two strains are present in Argentina. It was found that the strain-diagnostic haplotypes of the COI and Tpi genes subdivided the Argentina population into two major groups. Each group displayed biases in their distribution among different host plants that were generally consistent with expected strain behavior. The overall results indicated that Argentina fall armyworm exhibit similar genetics and behavior to populations in the rest of the hemisphere. In addition, the Argentina populations had comparable haplotype frequencies to those from Brazil and Texas, consistent with possible interactions with these fall armyworm groups, but appeared to have had minimal exchanges with those from Puerto Rico or Florida.     

Neuroprotective and anticonvulsant effects of organic and conventional purple grape juices on seizures in Wistar rats induced by pentylenetetrazole

Epilepsy is the most common neurological disorder worldwide. Studies have shown that recurrent seizures may increase the concentration of reactive oxygen species, which can lead to oxidative stress and neuronal damage. These seizures result in substantial deleterious effects on an individual's health. Organic and conventional grape juices are rich in polyphenols, compounds with important antioxidant activity. However, these juices could have differences in their polyphenol content. The aim of this study was to investigate the neuroprotective and anticonvulsant effects of organic and conventional grape juice treatments in Wistar rats against pentylenetetrazole (a convulsant drug)-induced damage. In addition, we evaluated potential behavioral changes in rats treated with the juices and the polyphenolic profile of those samples. Animals (n=16 in each group) received treatment with saline, organic or conventional grape juice for 17 days. On the eighteenth day, behavioral changes were evaluated by an open field test. Afterwards, half of the rats from each group received pentylenetetrazole and were observed for 30 min to evaluate possible seizure characteristics. The animals were subsequently killed by decapitation and their hippocampus, cerebellum and cerebral cortex tissues were isolated. The results of this study showed that neither organic nor conventional grape juice altered the behavior parameters, and no statistical differences were observed in the seizure characteristics of the groups. Nevertheless, both juice types were able to protect from lipid and protein oxidative damage, decrease nitric oxide content and increase enzymatic (superoxide dismutase and catalase) and non-enzymatic (sulfhydryl protein) antioxidant defenses in brain tissues following pentylenetetrazole-induced seizures. In general, organic juice showed superior results in each test, probably due to its higher polyphenol content relative to conventional juice. These results indicate that grape juices can provide further insight into natural neuroprotective compounds and may lead to the development of new therapeutic strategies for epileptic patients.     

Leishmania (Viannia) braziliensis: insights on subcellular distribution and biochemical properties of heparin-binding proteins

Leishmaniasis is a vector-borne disease and an important public health issue. Glycosaminoglycan ligands in Leishmania parasites are potential targets for new strategies to control this disease. We report the subcellular distribution of heparin-binding proteins (HBPs) in Leishmania (Viannia) braziliensis and specific biochemical characteristics of L. (V.) braziliensis HBPs. Promastigotes were fractionated, and flagella and membrane samples were applied to HiTrap Heparin affinity chromatography columns. Heparin-bound fractions from flagella and membrane samples were designated HBP Ff and HBP Mf, respectively. Fraction HBP Ff presented a higher concentration of HBPs relative to HBP Mf, and SDS-PAGE analyses showed 2 major protein bands in both fractions (65 and 55 kDa). The 65 kDa band showed gelatinolytic activity and was sensitive to inhibition by 1,10-phenanthroline. The localization of HBPs on the promastigote surfaces was confirmed using surface plasmon resonance (SPR) biosensor analysis by binding the parasites to a heparin-coated sensor chip; that was inhibited in a dose-dependent manner by pre-incubating the parasites with variable concentrations of heparin, thus indicating distinct heparin-binding capacities for the two fractions. In conclusion, protein fractions isolated from either the flagella or membranes of L. (V.) braziliensis promastigotes have characteristics of metallo-proteinases and are able to bind to glycosaminoglycans.     

Measurement of hemodynamics in human carotid artery using ultrasound and computational fluid dynamics.

The objective of the study was to investigate the feasibility of using computational fluid dynamic modeling (CFD) with noninvasive ultrasound measurements to determine time-variant three-dimensional (3D) carotid arterial hemodynamics in humans in vivo. The effects of hyperoxia and hypoxic hypercapnia on carotid artery local hemodynamics were examined by use of this approach. Six normotensive volunteers followed a double-blind randomized crossover design. Blood pressure, heart rate, and carotid blood flow were measured while subjects breathed normal air, a mixture of 5% CO(2) and 15% O(2) (hypoxic hypercapnia), and 100% O(2) (hyperoxia). Carotid artery geometry was reconstructed on the basis of B-mode ultrasound images by using purpose-built image processing software. Time-variant 3D carotid hemodynamics were estimated by using finite volume-based CFD. Systemic blood pressure was not significantly affected by hyperoxia or hypoxic hypercapnia, but heart rate decreased significantly with hyperoxia. There was an increase in diastolic flow velocity in the external carotid artery after hypoxic hypercapnia, but otherwise carotid blood flow velocities did not change significantly. Compared with normal air, hyperoxic conditions were associated with a decrease in the width of the region of flow separation in the external carotid artery. During hyperoxia, there was also an increase in the minimum and a decrease in maximum shear stress in the bifurcation and hence a reduction in cyclic variation in shear stress. Hypoxic hypercapnia was associated with a reduced duration of flow separation in the external carotid artery and an increase in the minimum shear stress without affecting the cyclic variation in shear stress. This study demonstrates the feasibility of using noninvasive ultrasound techniques in conjunction with CFD to describe time-variant 3D hemodynamics in the human carotid arterial bifurcation in vivo.     

Versatility of the capsular genes during biofilm formation by Streptococcus pneumoniae

Streptococcus pneumoniae forms part of the natural microbiota of the nasopharynx. For the pneumococcus to cause infection, colonization needs to occur and this process is mediated by adherence of bacteria to the respiratory epithelium. Although the capsular polysaccharide (CPS) of S. pneumoniae is known to be important for infection to occur, its role in colonization is controversial. Biofilm models are starting to emerge as a promising tool to investigate the role of CPS during nasopharyngeal carriage, which is the first step in the dissemination and initiation of a pneumococcal infection. Using a well-defined model system to analyse in vitro biofilm formation in pneumococcus, here we explore the molecular changes underlying the appearance of capsular mutants using type 3 S. pneumoniae cells. Spontaneous colony phase variants show promoter mutations, as well as duplications, deletions and point mutations in the cap3A gene, which codes for a UDP-glucose dehydrogenase (UDP-GlcDH). Increased biofilm-forming capacity could usually be correlated with a reduction both in colony size and in the relative amount of CPS present on the cell surface of each colony variant. However, a mutation in Cap3A Thr83Ile (a strictly conserved residue in bacterial UDP-GlcDHs) that resulted in very low CPS production also led to impaired biofilm formation. We propose that non-encapsulated mutants of pneumococcal type 3 strains are essentially involved in the initial stages (the attachment stage) of biofilm formation during colonization/pathogenesis.     

Chronic hyperhomocysteinemia alters antioxidant defenses and increases DNA damage in brain and blood of rats: protective effect of folic acid

We have previously demonstrated that acute hyperhomocysteinemia induces oxidative stress in rat brain. In the present study, we initially investigated the effect of chronic hyperhomocysteinemia on some parameters of oxidative damage, namely total radical-trapping antioxidant potential and activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), as well as on DNA damage in parietal cortex and blood of rats. We also evaluated the effect of folic acid on biochemical alterations elicited by hyperhomocysteinemia. Wistar rats received daily subcutaneous injection of Hcy (0.3-0.6 micromol/g body weight), and/or folic acid (0.011 micromol/g body weight) from their 6th to their 28th day of life. Twelve hours after the last injection the rats were sacrificed, parietal cortex and total blood was collected. Results showed that chronic homocysteine administration increased DNA damage, evaluated by comet assay, and disrupted antioxidant defenses (enzymatic and non-enzymatic) in parietal cortex and blood/plasma. Folic acid concurrent administration prevented homocysteine effects, possibly by its antioxidant and DNA stability maintenance properties. If confirmed in human beings, our results could propose that the supplementation of folic acid can be used as an adjuvant therapy in disorders that accumulate homocysteine.     

Structural basis of the lisinopril-binding specificity in N- and C-domains of human somatic ACE

Angiotensin I-converting enzyme (ACE) is a dipeptidyl carboxypeptidase which converts angiotensin I into the vasopressor peptide angiotensin II and also inactivates the hypotensive peptide bradykinin, playing an important role in blood pressure regulation. The present work describes the molecular modeling of the N-terminal human somatic ACE in complex with the inhibitor lisinopril, identifying the residues involved in the inhibitor-binding pocket. The obtained results identify differences in the lisinopril lysine moiety-binding residues for N- and C-terminals of sACE domains and an important carboxy-terminal proline hydrophobic accommodations mediated by the aromatic ring of Tyr532 and Tyr1128 residues, respectively. The present model will be useful for the development of a new inhibitor family based on the natural BPP peptides and derivatives, or even to improve the binding capacities and the domain specificity of the already known inhibitors.