Filmes de Langmuir-Blodgett de nanopartículas de prata

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anatomia floral e ontogenia de espécies dímeras de Paepalanthus Mart. (Eriocaulaceae, Poales) e seu significado evolutivo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise da formação de Complexos Regionais de Segurança (CRS): um estudo comparativo entre a América do Sul e o leste asiático

Pós-graduação em Relações Internacionais (UNESP - UNICAMP - PUC-SP) - FFC

Is Drosera meristocaulis a pygmy sundew? evidence of a long-distance dispersal between Western Australia and northern South America

Background and aims South America and Oceania possess numerous floristic similarities, often confirmed by morphological and molecular data. The carnivorous Drosera meristocaulis (Droseraceae), endemic to the Neblina highlands of northern South America, was known to share morphological characters with the pygmy sundews of Drosera sect. Bryastrum, which are endemic to Australia and New Zealand. The inclusion of D. meristocaulis in a molecular phylogenetic analysis may clarify its systematic position and offer an opportunity to investigate character evolution in Droseraceae and phylogeographic patterns between South America and Oceania. Methods Drosera meristocaulis was included in a molecular phylogenetic analysis of Droseraceae, using nuclear internal transcribed spacer (ITS) and plastid rbcL and rps16 sequence data. Pollen of D. meristocaulis was studied using light microscopy and scanning electron microscopy techniques, and the karyotype was inferred from root tip meristem. Key Results The phylogenetic inferences (maximum parsimony, maximum likelihood and Bayesian approaches) substantiate with high statistical support the inclusion of sect. Meristocaulis and its single species, D. meristocaulis, within the Australian Drosera clade, sister to a group comprising species of sect. Bryastrum. A chromosome number of 2n = approx. 32–36 supports the phylogenetic position within the Australian clade. The undivided styles, conspicuous large setuous stipules, a cryptocotylar (hypogaeous) germination pattern and pollen tetrads with aperture of intermediate type 7–8 are key morphological traits shared between D. meristocaulis and pygmy sundews of sect. Bryastrum from Australia and New Zealand. Conclusions The multidisciplinary approach adopted in this study (using morphological, palynological, cytotaxonomic and molecular phylogenetic data) enabled us to elucidate the relationships of the thus far unplaced taxon D. meristocaulis. Long-distance dispersal between southwestern Oceania and northern South America is the most likely scenario to explain the phylogeographic pattern revealed.

Intermittent hypoxia inhibits clearance of triglyceride-rich lipoproteins and inactivates adipose lipoprotein lipase in a mouse model of sleep apnoea

Delayed lipoprotein clearance is associated with atherosclerosis. This study examined whether chronic intermittent hypoxia (CIH), a hallmark of obstructive sleep apnoea (OSA), can lead to hyperlipidaemia by inhibiting clearance of triglyceride rich lipoproteins (TRLP). Male C57BL/6J mice on high-cholesterol diet were exposed to 4 weeks of CIH or chronic intermittent air (control). FIO2 was decreased to 6.5 once per minute during the 12 h light phase in the CIH group. After the exposure, we measured fasting lipid profile. TRLP clearance was assessed by oral gavage of retinyl palmitate followed by serum retinyl esters (REs) measurements at 0, 1, 2, 4, 10, and 24 h. Activity of lipoprotein lipase (LpL), a key enzyme of lipoprotein clearance, and levels of angiopoietin-like protein 4 (Angptl4), a potent inhibitor of the LpL activity, were determined in the epididymal fat pads, skeletal muscles, and heart. Chronic intermittent hypoxia induced significant increases in levels of total cholesterol and triglycerides, which occurred in TRLP and LDL fractions (P 0.05 for each comparison). Compared with control mice, animals exposed to CIH showed increases in REs throughout first 10 h after oral gavage of retinyl palmitate (P 0.05), indicating that CIH inhibited TRLP clearance. CIH induced a 5-fold decrease in LpL activity (P 0.01) and an 80 increase in Angptl4 mRNA and protein levels in the epididymal fat, but not in the skeletal muscle or heart. CIH decreases TRLP clearance and inhibits LpL activity in adipose tissue, which may contribute to atherogenesis observed in OSA.

Phylogeny of Lundia (Bignoniaceae) based on ndhF and PepC sequences

The circumscription of genera belonging to tribe Bignonieae (Bignoniaceae) has traditionally been complex, with only a few genera having stable circumscriptions in the various classification systems proposed for the tribe. The genus Lundia, for instance, is well characterized by a series of morphological synapomorphies and its circumscription has remained quite stable throughout its history. Despite the stable circumscription of Lundia, the circumscription of species within the genus has remained problematic. This study aims to reconstruct the phylogeny of Lundia in order to refine species circumscriptions, gain a better understanding of relationships between taxa, and identify potential morphological synapomorphies for species and major clades. We sampled 26 accessions representing 13 species of Lundia, and 5 outgroups, and reconstructed the phylogeny of the genus using a chloroplast (ndhF) and a nuclear marker (PepC). Data derived from sequences of the individual loci were analyzed using parsimony and Bayesian inference, and the combined molecular dataset was analyzed with Bayesian methods. The monophyly of Lundia nitidula, a species with a particularly complex circumscription, was tested using Shimodaira-Hasegawa (SH) test and the approximately unbiased test for phylogenetic tree selection (AU test). In addition, 40 morphological characters were mapped onto the tree that resulted from the analysis of the combined molecular dataset in order to identify morphological synapomorphies of individual species and major clades. Lundia and most species currently recognized within the genus were strongly supported as monophyletic in all analyses. One species, Lundia nitidula, was not resolved as monophyletic, but the monophyly of this species was not rejected by the AU and SH tests. Lundia sect. Eriolundia is resolved as paraphyletic in all analyses, while Lundia sect. Eulundia is monophyletic and supported by the same morphological characters traditionally used to circumscribe this section. The phylogeny of Lundia contributed important information for a better circumscription of species and served as basis the taxonomic revision of the genus.

Subgroup-specific structural variation across 1,000 medulloblastoma genomes

Medulloblastoma, the most common malignant paediatric brain tumour, is currently treated with nonspecific cytotoxic therapies including surgery, whole-brain radiation, and aggressive chemotherapy. As medulloblastoma exhibits marked intertumoural heterogeneity, with at least four distinct molecular variants, previous attempts to identify targets for therapy have been underpowered because of small samples sizes. Here we report somatic copy number aberrations (SCNAs) in 1,087 unique medulloblastomas. SCNAs are common in medulloblastoma, and are predominantly subgroup-enriched. The most common region of focal copy number gain is a tandem duplication of SNCAIP, a gene associated with Parkinson's disease, which is exquisitely restricted to Group 4 alpha. Recurrent translocations of PVT1, including PVT1-MYC and PVT1-NDRG1, that arise through chromothripsis are restricted to Group 3. Numerous targetable SCNAs, including recurrent events targeting TGF-beta signalling in Group 3, and NF-kappa B signalling in Group 4, suggest future avenues for rational, targeted therapy.

Acute hypoxia induces hypertriglyceridemia by decreasing plasma triglyceride clearance in mice

Jun JC, Shin MK, Yao Q, Bevans-Fonti S, Poole J, Drager LF, Polotsky VY. Acute hypoxia induces hypertriglyceridemia by decreasing plasma triglyceride clearance in mice. Am J Physiol Endocrinol Metab 303: E377-E388, 2012. First published May 22, 2012; doi:10.1152/ajpendo.00641.2011.-Obstructive sleep apnea (OSA) induces intermittent hypoxia (IH) during sleep and is associated with elevated triglycerides (TG). We previously demonstrated that mice exposed to chronic IH develop elevated TG. We now hypothesize that a single exposure to acute hypoxia also increases TG due to the stimulation of free fatty acid (FFA) mobilization from white adipose tissue (WAT), resulting in increased hepatic TG synthesis and secretion. Male C57BL6/J mice were exposed to FiO(2) = 0.21, 0.17, 0.14, 0.10, or 0.07 for 6 h followed by assessment of plasma and liver TG, glucose, FFA, ketones, glycerol, and catecholamines. Hypoxia dose-dependently increased plasma TG, with levels peaking at FiO(2) = 0.07. Hepatic TG levels also increased with hypoxia, peaking at FiO(2) = 0.10. Plasma catecholamines also increased inversely with FiO(2). Plasma ketones, glycerol, and FFA levels were more variable, with different degrees of hypoxia inducing WAT lipolysis and ketosis. FiO(2) = 0.10 exposure stimulated WAT lipolysis but decreased the rate of hepatic TG secretion. This degree of hypoxia rapidly and reversibly delayed TG clearance while decreasing [H-3]triolein-labeled Intralipid uptake in brown adipose tissue and WAT. Hypoxia decreased adipose tissue lipoprotein lipase (LPL) activity in brown adipose tissue and WAT. In addition, hypoxia decreased the transcription of LPL, peroxisome proliferator-activated receptor-gamma, and fatty acid transporter CD36. We conclude that acute hypoxia increases plasma TG due to decreased tissue uptake, not increased hepatic TG secretion.

Is Drosera meristocaulis a pygmy sundew? Evidence of a long-distance dispersal between Western Australia and northern South America

South America and Oceania possess numerous floristic similarities, often confirmed by morphological and molecular data. The carnivorous Drosera meristocaulis (Droseraceae), endemic to the Neblina highlands of northern South America, was known to share morphological characters with the pygmy sundews of Drosera sect. Bryastrum, which are endemic to Australia and New Zealand. The inclusion of D. meristocaulis in a molecular phylogenetic analysis may clarify its systematic position and offer an opportunity to investigate character evolution in Droseraceae and phylogeographic patterns between South America and Oceania. was included in a molecular phylogenetic analysis of Droseraceae, using nuclear internal transcribed spacer (ITS) and plastid rbcL and rps16 sequence data. Pollen of D. meristocaulis was studied using light microscopy and scanning electron microscopy techniques, and the karyotype was inferred from root tip meristem. The phylogenetic inferences (maximum parsimony, maximum likelihood and Bayesian approaches) substantiate with high statistical support the inclusion of sect. Meristocaulis and its single species, D. meristocaulis, within the Australian Drosera clade, sister to a group comprising species of sect. Bryastrum. A chromosome number of 2n approx. 3236 supports the phylogenetic position within the Australian clade. The undivided styles, conspicuous large setuous stipules, a cryptocotylar (hypogaeous) germination pattern and pollen tetrads with aperture of intermediate type 78 are key morphological traits shared between D. meristocaulis and pygmy sundews of sect. Bryastrum from Australia and New Zealand. The multidisciplinary approach adopted in this study (using morphological, palynological, cytotaxonomic and molecular phylogenetic data) enabled us to elucidate the relationships of the thus far unplaced taxon D. meristocaulis. Long-distance dispersal between southwestern Oceania and northern South America is the most likely scenario to explain the phylogeographic pattern revealed.

Period determination in the food-entrainable and methamphetamine-sensitive circadian oscillator(s)

Daily rhythmic processes are coordinated by circadian clocks, which are present in numerous central and peripheral tissues. In mammals, two circadian clocks, the food-entrainable oscillator (FEO) and methamphetamine-sensitive circadian oscillator (MASCO), are "black box" mysteries because their anatomical loci are unknown and their outputs are not expressed under normal physiological conditions. In the current study, the investigation of the timekeeping mechanisms of the FEO and MASCO in mice with disruption of all three paralogs of the canonical clock gene, Period, revealed unique and convergent findings. We found that both the MASCO and FEO in Per1(-/-)/Per2(-/-)/Per3(-/-) mice are circadian oscillators with unusually short (similar to 21 h) periods. These data demonstrate that the canonical Period genes are involved in period determination in the FEO and MASCO, and computational modeling supports the hypothesis that the FEO and MASCO use the same timekeeping mechanism or are the same circadian oscillator. Finally, these studies identify Per1(-/-)/Per2(-/-)/Per3(-/-) mice as a unique tool critical to the search for the elusive anatomical location(s) of the FEO and MASCO.

Baccharis umbellata (Asteraceae, Astereae): a new species endemic to the highest summits of Parana, Southern Brazil

Baccharis umbellata, a new species of Parana State, southern Brazil, is described. The new species, belonging to subgen. Baccharis sect. Agglomeratae, is easily recognized by the pedunculate heads arranged in an umbel-like capitulescence. Baccharis umbellata is a narrow endemic of the peaks of the southern range of Serra do Mar. It is morphologically most similar to the allopatric species B. platypoda, which mainly inhabits mountain summits in western and eastern South America. Illustrations, a distribution map, habitat information, and a conservation assessment are also provided for the new species.

Anomalous diffusion evidenced by particle tracking at high frame rates.

Diffusion is a common phenomenon in nature and generally is associated with a system trying to reach a local or a global equilibrium state, as a result of highly irregular individual particle motion. Therefore it is of fundamental importance in physics, chemistry and biology. Particle tracking in complex fluids can reveal important characteristics of its properties. In living cells, we coat the microbead with a peptide (RGD) that binds to integrin receptors at the plasma membrane, which connects to the CSK. This procedure is based on the hypothesis that the microsphere can move only if the structure where it is attached move as well. Then, the observed trajectory of microbeads is a probe of the cytoskeleton (CSK), which is governed by several factors, including thermal diffusion, pressure gradients, and molecular motors. The possibility of separating the trajectories into passive and active diffusion may give information about the viscoelasticity of the cell structure and molecular motors activity. And also we could analyze the motion via generalized Stokes-Einstein relation, avoiding the use of any active techniques. Usually a 12 to 16 Frames Per Second (FPS) system is used to track the microbeads in cell for about 5 minutes. Several factors make this FPS limitation: camera computer communication, light, computer speed for online analysis among others. Here we used a high quality camera and our own software, developed in C++ and Linux, to reach high FPS. Measurements were conducted with samples for 10£ and 20£ objectives. We performed sequentially images with different intervals, all with 2 ¹s exposure. The sequences of intervals are in milliseconds: 4 5 ms (maximum speed) 14, 25, 50 and 100 FPS. Our preliminary results highlight the difference between passive and active diffusion, since the passive diffusion is represented by a Gaussian in the distribution of displacements of the center of mass of individual beads between consecutive frames. However, the active process, or anomalous diffusion, shows as long tails in the distribution of displacements.

Comparison of physical properties of two exogenous surfactants: new parameter.

The pulmonary surfactant has essential physical properties for normal lung function. The most important property is the surface tension. In this work, it was evaluated the surface tension of two commercial exogenous surfactants used in surfactant replacement therapy, poractant alfa (Curosurf, Chiesi Farmaceuticals, Italy) and beractant (Survanta, Abbott Laboratories, USA) using new parameters. A Langmuir film balance (Minitrough, KSV Instruments, Finland) was used to measure surface tension of poractant alfa and beractant samples. For both samples, we prepared a solution of 1 mg/m dissolved in chloroform (100π`), which was applied over a subphase of milli-Q water (175 ml) in the chamber of the balance. The chamber has two moving barriers that can change its surface area between a maximal value of 112.5 cm 2 , and a minimal value of 22.5 cm 2, defining a balance cycle. Each surfactant had its surface tension evaluated during 20 balance cycles for three times. Four quantities were calculated from the experiment: Minimum Surface Tension (MTS), defined as the surface tension at minimal surface area during the first cycle; Mean Work Cycle (MWC), defined as the mean hysteresis area of the measured surface tension curve of the last 16 balance cycles; Critical Active Surface Area in Compression (CASAC) or in Expansion (CASAE), defined as the maximal chamber area where the surfactant is active on the surface in compression or expansion. The t-test was applied to verify for statistical significance of the results. Comproved with the MST is the same reported in literature, the differences between MWC, CASAC, and CASAE were statistically significant (p<0.001). The MWC, CASAC and CASAE were higher for poractant alfa than for beractant. A higher MWC for poractant alfa means higher elastic recoil of the lung in comparison with beractant. Using a different methodology, our results showed that poractant alfa is probably more effective in a surfactant replacement therapy than beractant due the use of poractant alfa in relation to the use of beractant in preterm infants with Respiratory Distress Syndrome (RDS).

Mechanical Alterations in airway smooth muscle after interaction with indoor pollutant – A mathematical model.

The viscoelasticity of mammalian lung is determined by the mechanical properties and structural regulation of the airway smooth muscle (ASM). The exposure to polluted air may deteriorate these properties with harmful consequences to individual health. Formaldehyde (FA) is an important indoor pollutant found among volatile organic compounds. This pollutant permeates through the smooth muscle tissue forming covalent bonds between proteins in the extracellular matrix and intracellular protein structure changing mechanical properties of ASM and inducing asthma symptoms, such as airway hyperresponsiveness, even at low concentrations. In the experimental scenario, the mechanical effect of FA is the stiffening of the tissue, but the mechanism behind this effect is not fully understood. Thus, the aim of this study is to reproduce the mechanical behavior of the ASM, such as contraction and stretching, under FA action or not. For this, it was created a two-dimensional viscoelastic network model based on Voronoi tessellation solved using Runge-Kutta method of fourth order. The equilibrium configuration was reached when the forces in different parts of the network were equal. This model simulates the mechanical behavior of ASM through of a network of dashpots and springs. This dashpot-spring mechanical coupling mimics the composition of the actomyosin machinery of ASM through the contraction of springs to a minimum length. We hypothesized that formation of covalent bonds, due to the FA action, can be represented in the model by a simple change in the elastic constant of the springs, while the action of methacholine (MCh) reduce the equilibrium length of the spring. A sigmoid curve of tension as a function of MCh doses was obtained, showing increased tension when the muscle strip was exposed to FA. Our simulations suggest that FA, at a concentration of 0.1 ppm, can affect the elastic properties of the smooth muscle ¯bers by a factor of 120%. We also analyze the dynamic mechanical properties, observing the viscous and elastic behavior of the network. Finally, the proposed model, although simple, incorporates the phenomenology of both MCh and FA and reproduces experimental results observed with in vitro exposure of smooth muscle to FA. Thus, this new mechanical approach incorporates several well know features of the contractile system of the cells in a tissue level model. The model can also be used in different biological scales.

Mechanical Measurements Of Two Exogenous Surfactants Using A Langmuir Film Balance:A Comparative Study

Rationale: The primary function of surfactant is to reduce the surface tension at air-liquid interface. In this study, the surface tension behavior of two commercial surfactants, poractant alfa (ChiesiFarmaceuticals,ltaly) and beractant (Abbott Laboratories,USA), were evaluated,using new parameters. Methods: We used a Langmuir film balance (Minitrough,KSV lnstruments,Finland) to measure of surface tension of both poractant alfa and beractant samples. For both samples,we prepared a solution of 1 mg/mdl dissolved in chloroform. The solution (1uL) was applied over a subphase of milli-Q water (175 ml) in the chamber of the balance. The chamber has two moving barriers that can change its surface area between a maximum value of 112.5 cm2 anda minimum value of 22.5 cm2, defining a balance cycle.lhree sample's films were evaluated for each sample, during 20 balance cycles. Here quantify two new variables, which is the mean hysteresis area of the measured curve surface tension of the last 16 balance cycles,defined here as Mean Work Cycle (MWC), and the moment that the surfactant is active in the surface, this measure is defined here as Active Surface Area Critical in the compression (ASACC) and the expansion (ASACE). The test was applied to compare the statistical significance of the results.