Genetic diversity of four populations of Qualea grandiflora Mart. in fragments of the Brazilian Cerrado

We analyzed the genetic structure and diversity of Qualea grandiflora Mart., the most abundant woody species in the Brazilian Cerrado. Eight microsatellite loci were used to analyze samples from four populations subjected to different types of anthropic pressure, distributed throughout the state of São Paulo in the regions of Assis, Brotas, Itirapina and Pedregulho. Results indicated a mean number of 12 alleles per locus, but only six effective alleles. Alleles private to particular populations and rare alleles were also detected. An excess of homozygotes and moderate levels of inbreeding were observed. No clones were identified. All populations departed from Hardy–Weinberg equilibrium (p < 0.05). Spatial structure was observed in the distribution of specimens in distance classes ranging from 30 to 40 km and three genetic clusters were identified, with genotypes in the Pedregulho population differing from the others by up to 90 %. The influence of the Wahlund effect on the studied populations lies between 8.5 and 53.3 %. Estimates of effective population size were low (<10), and the minimum viable area for conservation in the short-, medium- and long-term was estimated to be between 4 and 184 ha. Gene flow was high enough to counter the effects of genetic drift. The genetic diversity and divergence between the studied populations indicated that the Pedregulho population should be considered an Evolutionary Significant Unit and a Management Unit.     

Development and regeneration of the retinotectal map in goldfish: a computational study

We present a simple computational model to study the interplay of activity-dependent and intrinsic processes thought to be involved in the formation of topographic neural projections. Our model consists of two input layers which project to one target layer. The connections between layers are described by a set of synaptic weights. These weights develop according to three interacting developmental rules: (i) an intrinsic fibre-target interaction which generates chemospecific adhesion between afferent fibres and target cells; (ii) an intrinsic fibre-fibre interaction which generates mutual selective adhesion between the afferent fibres; and (iii) an activity-dependent fibre-fibre interaction which implements Hebbian learning. Additionally, constraints are imposed to keep synaptic weights finite. The model is applied to a set of eleven experiments on the regeneration of the retinotectal projection in goldfish. We find that the model is able to reproduce the outcome of an unprecedented range of experiments with the same set of model parameters, including details of the size of receptive and projective fields. We expect this mathematical framework to be a useful tool for the analysis of developmental processes in general. <br>     

Virtual reality training of lucid dreaming

Metacognitive reflections on one''s current state of mind are largely absent during dreaming. Lucid dreaming as the exception to this rule is a rare phenomenon; however, its occurrence can be facilitated through cognitive training. A central idea of respective training strategies is to regularly question one''s phenomenal experience: is the currently experienced world real, or just a dream? Here, we tested if such lucid dreaming training can be enhanced with dream-like virtual reality (VR): over the course of four weeks, volunteers underwent lucid dreaming training in VR scenarios comprising dream-like elements, classical lucid dreaming training or no training. We found that VR-assisted training led to significantly stronger increases in lucid dreaming compared to the no-training condition. Eye signal-verified lucid dreams during polysomnography supported behavioural results. We discuss the potential mechanisms underlying these findings, in particular the role of synthetic dream-like experiences, incorporation of VR content in dream imagery serving as memory cues, and extended dissociative effects of VR session on subsequent experiences that might amplify lucid dreaming training during wakefulness.This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation''.     

Inhibition of α-Glycosidase by Lippia dulcis Trevir. (Verbenaceae) Preparations,Quantification of Verbascoside,and Study of Its Molecular Docking

This study aimed to quantify verbascoside (VEB), perform molecular docking studies of VEB with the α-glucosidase (GL) of Bacillus stearothermophilus, and evaluate the inhibition of the enzyme by L. dulcis preparations. The substrate concentration and presence of reduced glutathione were evaluated for their effect on the in vitro inhibition of the GL enzyme. Assays were also performed in the presence and absence of simulated gastric fluid. The antidiabetic fractions 2 and 3 were the most inhibited GL, but their activity were significantly decreased in the presence of gastric fluid. Chromatographic analyses confirmed the predominant presence of VEB in the samples. The samples had VEB concentrations between 49.9 and 243.5 mg/g. Simulation of the molecular docking of VEB were consistent with its GL-inhibitory activity. It can conclude that the crude ethanol extract and fractions show inhibitory activity against the GL enzyme.     

Comparative study on digestive lipase activities on the self emulsifying excipient Labrasol, medium chain glycerides and PEG esters

Labrasol is a lipid-based self-emulsifying excipient used in the preparation of lipophilic drugs intended for oral delivery. It is mainly composed of PEG esters and glycerides with medium acyl chains, which are potential substrates for digestive lipases. The hydrolysis of Labrasol by porcine pancreatic extracts, human pancreatic juice and several purified digestive lipases was investigated in the present study. Classical human pancreatic lipase (HPL) and porcine pancreatic lipase, which are the main lipases involved in the digestion of dietary triglycerides, showed very low levels of activity on the entire Labrasol excipient as well as on separated fractions of glycerides and PEG esters. On the other hand, gastric lipase, pancreatic lipase-related protein 2 (PLRP2) and carboxyl ester hydrolase (CEH) showed high specific activities on Labrasol. These lipases were found to hydrolyze the main components of Labrasol (PEG esters and monoglycerides) used as individual substrates, whereas these esters were found to be poor substrates for HPL. The lipolytic activity of pancreatic extracts and human pancreatic juice on Labrasol(R) is therefore mainly due to the combined action of CEH and PLRP2. These two pancreatic enzymes, together with gastric lipase, are probably the main enzymes involved in the in vivo lipolysis of Labrasol taken orally.     

Cold sweetening in diploid potato: mapping quantitative trait loci and candidate genes

A candidate gene approach has been used as a first step to identify the molecular basis of quantitative trait variation in potato. Sugar content of tubers upon cold storage was the model trait chosen because the metabolic pathways involved in starch and sugar metabolism are well known and many of the genes have been cloned. Tubers of two F(1) populations of diploid potato grown in six environments were evaluated for sugar content after cold storage. The populations were genotyped with RFLP, AFLP, and candidate gene markers. QTL analysis revealed that QTL for glucose, fructose, and sucrose content were located on all potato chromosomes. Most QTL for glucose content mapped to the same positions as QTL for fructose content. QTL explaining >10% of the variability for reducing sugars were located on linkage groups I, III, VII, VIII, IX, and XI. QTL consistent across populations and/or environments were identified. QTL were linked to genes encoding invertase, sucrose synthase 3, sucrose phosphate synthase, ADP-glucose pyrophosphorylase, sucrose transporter 1, and a putative sucrose sensor. The results suggest that allelic variants of enzymes operating in carbohydrate metabolic pathways contribute to the genetic variation in cold sweetening.     

Corpus Christi strain-induced protection to Trypanosoma cruzi infection in C3H(He) mice: effective dose, time, route, and number of vaccinations

The study of the parameters affecting Corpus Christi strain-induced protection in C3H(He) mice against Brazil strain T. cruzi infection is reported herein. A dose of 10(7) Corpus Christi epimastigotes was found to be the most effective dose for protection. Vaccination of mice 5 days to 11 wk prior to infection was determined to be the optimal time interval for protection. The subcutaneous route for vaccination and infection provides the most effective protection to experimental animals. Multiple inoculations with Corpus Christi, whether live or freeze thawed, increased the protective effect only slightly. The Corpus Christi strain of T. cruzi has proved to be quite suitable in providing protection to highly susceptible C3H(He) mice against an infection with the virulent Brazil strain of T. cruzi.