Pre-treatment effects on coral skeletal delta\u3csup\u3e13\u3c/sup\u3eC and delta\u3csup\u3e18\u3c/sup\u3eO

Pre-treatments are often used to remove organic “contaminant” material prior to isotopic analyses of coral skeletal samples. Here we conducted three experiments to test the pre-treatment effect of water, 30% hydrogen peroxide (H2O2), and household bleach [5.25% sodium hypochlorite (NaClO3) and 0.15% sodium hydroxide (NaOH)], on the stable isotopic composition of coral skeletal samples. First, using a mass balance approach we calculated the expected change in skeletal delta13C due to the removal of all organic carbon. The model showed that (1) the removal of organic carbon (which has a low delta13C value relative to skeletal delta13C) from the skeletal sample should theoretically result in a higher delta13C value of the remaining organic-carbon-free carbonate, and that (2) only at the highest concentrations of skeletal organic carbon within the tissue layer of corals is the contribution of the organic carbon to the overall delta13C skeletal value potentially large enough to be detectable by mass spectrometry. We then conducted two sets of experiments to test the model where we pre-treated a large number of skeletal samples from five species of corals with water, H2O2, bleach, or no pre-treatment for 24 h. Skeletal delta13C generally decreased significantly with water, bleach, and H2O2 pre-treatments which is contrary to the model-predicted increase in delta13C following such pre-treatments. Thus, organic carbon within the skeleton is not a net source of contamination to delta13C analyses. Skeletal delta18O decreased the most with water and bleach pre-treatments. In addition, the effect of H2O2 or bleach pre-treatments on either delta13C or delta18O was not consistent among species or locations. The direction of change in delta13C and delta18O with pre-treatments was no different for skeletal samples taken within or below the tissue layer. Based on our results, we suggest that pre-treatment is not necessary and recommend that pre-treatment not be performed on coral skeletal samples prior to stable isotope analysis to avoid any pre-treatment-induced variability that could significantly compromise inter-colony and inter-species comparisons

Bilayered constructs aimed at osteochondral strategies : the influence of media supplements in the osteogenic and chondrogenic differentiation of amniotic fluid-derived stem cells

injuries and aging associated diseases that affect joints. This study reports the development of a bilayered scaffold, which consists of both bone and cartilage regions. On the other hand, amniotic fluid-derived stem cells (AFSCs) could be differentiated into either osteogenic or chondrogenic cells, respectively. In this study we have developed a bilayered scaffolding system, which includes a starch/polycaprolactone (SPCL) scaffold for osteogenesis and an agarose hydrogel for chondrogenesis. AFSC-seeded scaffolds were cultured for 1 or 2 weeks in an osteochondral-defined culture medium containing both osteogenic and chondrogenic differentiation factors. Additionally, the effect of the presence or absence of insulin-like growth factor-1 (IGF-1) in the culture medium was assessed. Cell viability and phenotypic expression were assessed within the constructs in order to determine the influence of the osteochondral differentiation medium. The results indicated that, after osteogenic differentiation, AFSCs that had been seeded onto SPCL scaffolds did not require osteochondral medium to maintain their phenotype, and they produced a protein-rich, mineralized extracellular matrix (ECM) for up to 2 weeks. However, AFSCs differentiated into chondrocyte-like cells appeared to require osteochondral medium, but not IGF-1, to synthesize ECM proteins and maintain the chondrogenic phenotype. Thus, although IGF-1 was not essential for creating osteochondral constructs with AFSCs in this study, the osteochondral supplements used appear to be important to generate cartilage in long-term tissue engineering approaches for osteochondral interfaces. In addition, constructs generated from agarose–SPCL bilayered scaffolds containing pre-differentiated AFSCs may be useful for potential applications in regeneration strategies for damaged or diseased joints.Fundação para a Ciência e a Tecnologia (FCT

Boosting BCG with recombinant modified vaccinia ankara expressing antigen 85A: Different boosting intervals and implications for efficacy trials

Objectives. To investigate the safety and immunogenicity of boosting BCG with modified vaccinia Ankara expressing antigen 85A (MVA85A), shortly after BCG vaccination, and to compare this first with the immunogenicity of BCG vaccination alone and second with a previous clinical trial where MVA85A was administered more than 10 years after BCG vaccination. Design. There are two clinical trials reported here: a Phase I observational trial with MVA85A; and a Phase IV observational trial with BCG. These clinical trials were all conducted in the UK in healthy, HIV negative, BCG naı¨ve adults. Subjects were vaccinated with BCG alone; or BCG and then subsequently boosted with MVA85A four weeks later (short interval). The outcome measures, safety and immunogenicity, were monitored for six months. The immunogenicity results from this short interval BCG prime–MVA85A boost trial were compared first with the BCG alone trial and second with a previous clinical trial where MVA85A vaccination was administered many years after vaccination with BCG. Results. MVA85A was safe and highly immunogenic when administered to subjects who had recently received BCG vaccination. When the short interval trial data presented here were compared with the previous long interval trial data, there were no significant differences in the magnitude of immune responses generated when MVA85A was administered shortly after, or many years after BCG vaccination. Conclusions. The clinical trial data presented here provides further evidence of the ability of MVA85A to boost BCG primed immune responses. This boosting potential is not influenced by the time interval between prior BCG vaccination and boosting with MVA85A. These findings have important implications for the design of efficacy trials with MVA85A. Boosting BCG induced anti-mycobacterial immunity in either infancy or adolescence are both potential applications for this vaccine, given the immunological data presented here. Trial Registration. ClinicalTrials.Oxford University was the sponsor for all the clinical trials reported here

The DNA damage and the DNA replication checkpoints converge at the MBF transcription factor

In fission yeast cells, Cds1 is the effector kinase of the DNA replication checkpoint. We previously showed that when the DNA replication checkpoint is activated, the repressor Yox1 is phosphorylated and inactivated by Cds1, resulting in activation of MluI-binding factor (MBF)-dependent transcription. This is essential to reinitiate DNA synthesis and for correct G1-to-S transition. Here we show that Cdc10, which is an essential part of the MBF core, is the target of the DNA damage checkpoint. When fission yeast cells are treated with DNA-damaging agents, Chk1 is activated and phosphorylates Cdc10 at its carboxy-terminal domain. This modification is responsible for the repression of MBF-dependent transcription through induced release of MBF from chromatin. This inactivation of MBF is important for survival of cells challenged with DNA-damaging agents. Thus Yox1 and Cdc10 couple normal cell cycle regulation in unperturbed conditions and the DNA replication and DNA damage checkpoints into a single transcriptional complex

Resonant tunneling diode photodetectors for optical communications

Resonant tunneling diodes (RTDs) have been extensively studied due to their potential applications in very high speed electronics, optical communications, and terahertz generation. In this work, we report the latest results on the characterization of the resonant tunneling diode photo-detectors (RTD-PDs), incorporating InGaAlAs light sensitive layers for sensing at the telecommunication wavelength of lambda = 1310 nm. We have measured responsivities up to 28.8 A/W and light induced voltage shift of 204.8 V/W for light injection powers around 0.25 mW.Fundacao para a Ciencia e a Tecnologia (FCT) [UID/Multi/00631/2013]; European Structural and Investment Funds (FEEI) through the Competitiveness and Internationalization Operational Program (COMPETE); FCT [ALG-01-0145-FEDER-016432/POCI-01-0145-FEDER-016432]; European Commission under the project iBROW [645369

Fnr (EtrA) acts as a fine-tuning regulator of anaerobic metabolism in \u3cem\u3eShewanella oneidensis\u3c/em\u3e MR-1

Background EtrA in Shewanella oneidensis MR-1, a model organism for study of adaptation to varied redox niches, shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulators Fnr in E. coli and Anr in Pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in Shewanella spp. is complex and not well understood. Results The expression of the nap genes, nrfA, cymA and hcp was significantly reduced in etrA deletion mutant EtrA7-1; however, limited anaerobic growth and nitrate reduction occurred, suggesting that multiple regulators control nitrate reduction in this strain. Dimethyl sulfoxide (DMSO) and fumarate reductase gene expression was down-regulated at least 2-fold in the mutant, which, showed lower or no reduction of these electron acceptors when compared to the wild type, suggesting both respiratory pathways are under EtrA control. Transcript analysis further suggested a role of EtrA in prophage activation and down-regulation of genes implicated in aerobic metabolism. Conclusion In contrast to previous studies that attributed a minor regulatory role to EtrA in Shewanella spp., this study demonstrates that EtrA acts as a global transcriptional regulator and, in conjunction with other regulators, fine-tunes the expression of genes involved in anaerobic metabolism in S. oneidensis strain MR-1. Transcriptomic and sequence analyses of the genes differentially expressed showed that those mostly affected by the mutation belonged to the Energy metabolism category, while stress-related genes were indirectly regulated in the mutant possibly as a result of a secondary perturbation (e.g. oxidative stress, starvation). We also conclude based on sequence, physiological and expression analyses that this regulator is more appropriately termed Fnr and recommend this descriptor be used in future publications