RGMa and RGMb expression pattern during chicken development suggest unexpected roles for these repulsive guidance molecules in notochord formation, somitogenesis, and myogenesis

Background: Repulsive guidance molecules (RGM) are high-affinity ligands for the Netrin receptor Neogenin, and they are crucial for nervous system development including neural tube closure; neuronal and neural crest cell differentiation and axon guidance. Recent studies implicated RGM molecules in bone morphogenetic protein signaling, which regulates a variety of developmental processes. Moreover, a role for RGMc in iron metabolism has been established. This suggests that RGM molecules may play important roles in non-neural tissues. Results: To explore which tissues and processed may be regulated by RGM molecules, we systematically investigated the expression of RGMa and RGMb, the only RGM molecules currently known for avians, in the chicken embryo. Conclusions: Our study suggests so far unknown roles of RGM molecules in notochord, somite and skeletal muscle development. Developmental Dynamics, 2012. (C) 2012 Wiley Periodicals, Inc.AFMAFMCNPqCNPqFAPESPFAPES

A genômica na bovinocultura de corte.

Genômica: definição e conceito; Aplicações da genômica; Perspectivas das aplicações da genômica

Selective activation of protein kinase C-δ and -ɛ by 6,11,12,14-tetrahydroxy-abieta-5,8,11,13-tetraene-7-one (coleon U)

6,11,12,14-tetrahydroxy-abieta-5,8,11,13-tetraene-7-one (coleon U) is a diterpene compound isolated from Plectranthus grandidentatus with an antiproliferative effect on several human cancer cell lines. Herein, we studied the modulatory activity of coleon U on individual isoforms of the three protein kinase C (PKC) subfamilies, classical (cPKC-α and -βI), novel (nPKC-δ and -ɛ) and atypical (aPKC-ζ), using a yeast PKC assay. The results showed that, whereas the PKC activator phorbol-12-myristate-13-acetate (PMA) activated every PKC tested except aPKC, coleon U had no effect on aPKC and cPKCs. Besides, the effect of coleon U on nPKCs was higher than that of PMA. This revealed that coleon U was a potent and selective activator of nPKCs. The isoform-selectivity of coleon U for nPKC-δ and -ɛ was confirmed using an in vitro PKC assay. Most importantly, while PMA activated nPKCs inducing an isoform translocation from the cytosol to the plasma membrane and a G2/M cell cycle arrest, coleon U induced nPKCs translocation to the nucleus and a metacaspase- and mitochondrial-dependent apoptosis. This work therefore reconstitutes in yeast distinct subcellular translocations of a PKC isoform and the subsequent distinct cellular responses reported for mammalian cells. Together, our study identifies a new isoform-selective PKC activator with promising pharmacological applications. Indeed, since coleon U has no effect on cPKCs and aPKC, recognised as anti-apoptotic proteins, and selectively induces an apoptotic pathway dependent on nPKC-δ and -ɛ activation, it represents a promising compound for evaluation as an anti-cancer drug.We are grateful to Dr. Nigel Goode for providing YEplac181-PKC-α, PKC-βI, PKC-δ, -PKC-ɛ and -PKC-ζ; to Dr. Heimo Riedel for providing YEp52-PKC-α and Yep51-PKC-βI; to Dr. Charles Rudin for providing pOW4-Bcl-xL; to Dr. Stéphen Manon for providing pCLbGFP-mt-GFP; to Joana Tavares for her help and technical advice in some experiments; to Cristina G-Marques for the previous isolation of coleon U; to Helena Vasconcelos for critical reading of the manuscript. We thank REQUIMTE/CEQUP and FCT (I&D No 8/94), POCTI (QCA III) and FEDER for financial support. I. Coutinho is recipient of a PhD fellowship from FCT (SFRH/BD/36066/2007).info:eu-repo/semantics/publishedVersio

Dye-sensitized solar cells using fluorone-based ionic liquids with improved cell efficiency

POCI-01-0145-FEDER-016387. POCI-01-0145-FEDER-007265. UID/QUI/50006/2019. LISBOA-01-0145-FEDER-402-022125. SFRH/BD/135087/2017.Six trihexyltetradecylphosphonium chloride (P6,6,6,14Cl) based ionic liquids (IL) with dianionic fluorone derivatives were synthesized with total exchange of chloride from the dianionic dye: Fluorescein (a), Rose Bengal (b), Phloxine B (c), Eosin B (d), Eosin Y (e) and Erythrosin B (f). Spectroscopic characterization of these viscous salts indicated the presence of the expected 1 or 2 strong absorption bands. A total of 12 compounds, as sodium (from a to f) or as trihexyltetradecylphosphonium dianion salts (from a′ to f′), were used for sensitization of nanocrystalline TiO2. Here, we report the sensitization activity of these metal free dyes in terms of current-potential curve, open-circuit potential, fill factor, and overall solar energy conversion efficiency which have been evaluated under 100 mW cm-2 light intensity. We developed a strategy to improve the light harvesting of these conventional dyes by simple cationic exchange which was accompanied by a minimum of 30% increase in the cell photovoltaic conversion efficiency. Also, for Eosin B the binding to TiO2 apparently allows reduction of the-NO2 electron-withdrawing group to-NO22-. This provides a new interaction between the reduced nitro group and the TiO2 surface, reflecting an improvement in the overall DSSC performance reaching its maximum of 0.65% efficiency after light DSSC soaking. Factors that improve DSSC performance like aggregate inhibition, increment of the electrode's quasi-Fermi level and slight red shift in the absorption spectra of the tested anionic dyes were achieved by simple cationic exchange.authorsversionpublishe

Tuning the ionic character of sodium dodecyl sulphate via counter-ion binding: an experimental and computational study

Solutions of surfactants exhibit remarkable features, such as a tunable amphiphilic character, which can further be varied for ionic surfactants through variations in their Coulombic interactions. These properties are very useful in many industrial applications such as in extraction, purification, and formulation processes, as detergents, wetting agents, or emulsifiers. Rather unexpectedly, the addition of tetrabutylammonium chloride ([N4,4,4,4]Cl) to solutions of the ionic surfactant of sodium dodecyl sulphate (SDS) results in the appearance of a phase transition above the lower critical solution temperature (LCST), a property usually associated with non-ionic surfactants. The aim of this study is to provide a detailed nanoscopic scenario on the interaction between SDS micelles and [N4,4,4,4]Cl moieties to better understand the nature of the LCST cloud point and how to confer it to a given ionic surfactant system. A coarse-grained molecular dynamics (CG-MD) computational framework, under the latest MARTINI 3.0 force field, was developed and validated using available literature data. The impact of [N4,4,4,4]Cl concentration in the phase of SDS micellar aqueous solutions was then characterized and compared using experimental results. Specifically, dynamic light scattering (DLS) measurements and small-angle X-ray scattering (SAXS) profiles were obtained at different [N4,4,4,4]+/[DS]- molar ratios (from 0.0 to 1.0) and compared with the CG-MD results. A good agreement between computer simulations and experimental findings was obtained, reinforcing the suitability of GC-MD to simulate complex phase behaviors. When the [N4,4,4,4]+/[DS]- molar ratio is 0.5, the system yielded clusters of enclosed small [DS]- aggregates. Thus, the CG-MD simulations showed the formation of mixed [DS]- and [N4,4,4,4]+ aggregates with [N4,4,4,4]+ cations acting as a bridge between small [DS]- micelles. The CG-MD simulation framework developed in this work captured the role of [N4,4,4,4]+ in the micellar phase transition whilst improving the results obtained with preceding computer models for which the limitations on capturing SDS and [N4,4,4,4]Cl mixtures in aqueous solutions are also shown in detail.publishe

Microbial degradation of hydrocarbons and its applications to enhanced oil recovery at lab scale

The renewed interest in Enhanced Oil Recovery (EOR) techniques as a consequence of the current oil prices is boosting the development of the Microbial Enhanced Oil Recovery (MEOR). This technique is useful to recover incremental oil from a reservoir beyond primary and secondary recovery operations and can be carried by the injection of exogenous or stimulation of indigenous microorganisms. This last approach is here investigated. In this work we address the isolation and identification of microorganisms from Brazilian heavy oil samples capable of producing biosurfactants and to promote the degradation of heavy oil fractions, in particular long-chain hydrocarbons.Different crude oil samples obtained from an oil reservoir were used to isolate microorganisms for application in MEOR. Most of isolates were Pseudomonas and Bacillus strains. The growth of different microbial isolates was studied under both aerobic and anaerobic conditions at 40ºC. These isolates were found to produce extracellular biosurfactants, reduce surface tension and showed a high emulsifying activity. In addition to these capabilities, we studied the ability of these microorganisms to degrade the heavy oil fraction, in particular long-chain hydrocarbons. Several parameters were studied, such as nutritional conditions, incubation time and paraffinic composition of the mixture. Our results show that some of the isolates displayed a capacity to degrade, under aerobic and anaerobic conditions, the large alkyl chains (18+ carbons in alkyl chains) and to reduce the viscosity of hydrocarbon mixtures. Our results, show the ability of the Bacillus subtilis strains to enhance the recovery of paraffinic oil on sand pack columns. These results suggest that the microorganisms’ here isolated have interesting characteristics to be applied for MEOR

Enhanced oil recovery under laboratory conditions using biosurfactant-producing microorganisms

Oil recovery comprises a primary phase, which produces oil using the natural pressure drive of the reservoir, and a secondary phase, which includes the injection of water to improve the flow of oil to the wellhead [1,2]. While primary recovery produces 5-10% of the original oil in place, recovery efficiencies in the secondary stage vary from 10% to 40% [1]. Most of the unrecovered oil (up to two-thirds of the total oil reserves) is trapped in the reservoir pores by high capillary forces [2]. Microbial Enhanced Oil Recovery (MEOR) is a tertiary oil recovery process where microorganisms and their metabolites are used to retrieve unrecoverable oil from mature reservoirs. Stimulation of biosurfactant production by indigenous or injected microorganisms can reduce the capillary forces that retain the oil into the reservoir. In this work, a sand pack column model was designed to simulate the oil recovery operations in oil reservoirs and evaluate the mobilization of residual oil by microorganisms. Three Bacillus subtilis strains (309, 311 and 573), previously isolated from crude oil samples, were used in this study. They grow and produce extracellular biosurfactants at 40ºC under anaerobic conditions in medium supplemented with hydrocarbons. Biosurfactants produced by those isolates reduce the surface tension of water from 72 to 30 mN/m, exhibit emulsifying activity and are not affected by exposure to high temperatures (121ºC) which makes them good candidates for application in biosurfactant mediated MEOR. Acrylic columns (250 ml) packed with acid washed sand were first flooded with water, after that saturated with paraffin, and then washed with water to remove the excess of paraffin. Afterwards, the isolates were injected into the columns with the optimized medium and incubated at 40ºC. After 14 days, the columns were flooded with water and the additional oil recovery (AOR) was calculated as the percentage of paraffin recovered. AOR using B. subtilis 309, 311 and 573 was 35.0 ± 1.0 %, 23.5 ± 1.2 % and 19.8 ± 1.9 %, respectively. The results obtained suggest that stimulation of biosurfactant production by these strains in the oil reservoir can contribute to mobilize entrapped oi

Isolation and study of microorganisms from oil samples for application in Microbial Enhanced Oil Recovery

"Author's personal copy"Microbial Enhanced Oil Recovery (MEOR) is potentially useful to increment oil recovery from a reservoir beyond primary and secondary recovery operations using microorganisms and their metabolites. Stimulation of bacterial growth for biosurfactant production and degradation of heavy oil fractions by indigenous microorganisms can enhance the fluidity and reduce the capillary forces that retain the oil into the reservoir. MEOR offers major advantages over conventional EOR, namely low energy consumption and independence of the price of crude oil. In this work, the isolation and identification of microorganisms capable of producing biosurfactants and promote degradation of long-chain n-alkanes under conditions existent in oil reservoirs were addressed. Among the isolated microorganisms, five Bacillus strains were able to produce extracellular biosurfactants at 40 C under anaerobic conditions in medium supplemented with hydrocarbons. Three isolates were selected as the higher biosurfactant producers. The obtained biosurfactants reduced the surface tension of water from 72 to 30 mN/m, exhibited emulsifying activity and were not affected by exposure to high temperatures (121 C). These characteristics make them good candidates for use at conditions usually existing in oil reservoirs. Furthermore, it was here shown for the first time that Bacillus strains were able to degrade large alkyl chains and reduce the viscosity of hydrocarbon mixtures under anaerobic conditions. The results obtained show that the isolated microorganisms are promising candidates for the development of enhanced oil recovery processes.This work was supported by PARTEX OIL AND GAS. Jorge F. B. Pereira acknowledges the financial support from Fundacao para a Ciencia e a Tecnologia through doctoral research grant SFRH/BD/60228/2009

Combined effects of bird extinctions and introductions in oceanic islands : Decreased functional diversity despite increased species richness

Aim We analyse the consequences of species extinctions and introductions on the functional diversity and composition of island bird assemblages. Specifically, we ask if introduced species have compensated the functional loss resulting from species extinctions. Location Seventy-four oceanic islands (> 100 km(2)) in the Atlantic, Pacific and Indian Oceans. Time period Late Holocene. Major taxa studied Terrestrial and freshwater bird species. Methods We compiled a species list per island (extinct and extant, native and introduced), and then compiled traits per species. We used single-trait analyses to assess the effects of past species extinctions and introductions on functional composition. Then, we used probabilistic hypervolumes in trait space to calculate functional richness and evenness of original versus present avifaunas of each island (and net change), and to estimate how functionally unique are extinct and introduced species on each island. Results The net effects of extinctions and introductions were: an increase in average species richness per island (alpha diversity), yet a decline in diversity across all islands (gamma diversity); an average increase in the prevalence of most functional traits, yet an average decline in functional richness and evenness, associated with the fact that extinct species were functionally more unique (when compared to extant natives) than introduced species. Main conclusions Introduced species are on average offsetting (and even surpassing) the losses of extinct species per island in terms of species richness, and they are increasing the prevalence of most functional traits. However, they are not compensating for the loss of functional richness due to extinctions. Current island bird assemblages are becoming functionally poorer, having lost unique species and being composed of functionally more redundant species. This is likely to have cascading repercussions on the functioning of island ecosystems. We highlight that taxonomic and functional biodiversity should be assessed simultaneously to understand the global impacts of human activities.Peer reviewe