Computer-Guided Trypanocidal Activity of Natural Lactones Produced by Endophytic Fungus of Euphorbia umbellata

Hundreds of millions of people worldwide are affected by Chagas’ disease caused by Trypanosoma cruzi. Since the current treatment lack efficacy, specificity, and suffers from several side-effects, novel therapeutics are mandatory. Natural products from endophytic fungi have been useful sources of lead compounds. In this study, three lactones isolated from an endophytic strain culture were in silico evaluated for rational guidance of their bioassay screening. All lactones displayed in vitro activity against T. cruzi epimastigote and trypomastigote forms. Notably, the IC₅₀ values of (+)-phomolactone were lower than benznidazole (0.86 vs. 30.78 μM against epimastigotes and 0.41 vs. 4.88 μM against trypomastigotes). Target-based studies suggested that lactones displayed their trypanocidal activities due to T. cruzi glyceraldehyde-3-phosphate dehydrogenase (TcGAPDH) inhibition, and the binding free energy for all three TcGAPDH-lactone complexes suggested that (+)-phomolactone has a lower score value (−3.38), corroborating with IC₅₀ assays. These results highlight the potential of these lactones for further anti-T. cruzi drug development.     

Diphenyl ditelluride targets brain selenoproteins in vivo: inhibition of cerebral thioredoxin reductase and glutathione peroxidase in mice after acute exposure

In this study, we investigated the effect of diphenyl ditelluride (PhTe)₂ administration (10 and 50?μmol/kg) on adult mouse behavioral performance as well as several parameters of oxidative stress in the brain and liver. Adult mice were injected with (PhTe)₂ or canola oil subcutaneously (s.c.) daily for 7?days. Results demonstrated that (PhTe)₂ induced prominent signs of toxicity (body weight loss), behavioral alterations and increased in lipid peroxidation in brain. 50?μmol/kg (PhTe)₂ inhibited blood δ-aminolevulinic acid dehydratase (δ-ALA-D), a redox sensitive enzyme. (PhTe)₂ caused an increase in cerebral non-protein thiol (NPSH) and protein thiol (PSH) groups. In the liver, 50?μmol/kg (PhTe)₂ decreased NPSH, but did not alter the content of protein thiol groups. (PhTe)₂ decreased cerebral antioxidant enzymes (catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), and thioredoxin reductase (TrxR). In liver, (PhTe)₂ increase SOD and GR and decreased GPx activity. Results obtained herein suggest that the brain was more susceptible to oxidative stress induced by (PhTe)₂ than the liver. Furthermore, we have demonstrated for the first time that TrxR is an in vivo target for (PhTe)_2. Combined, these results highlight a novel molecular mechanism involved in the toxicity of (PhTe)₂. In particular the inhibition of important selenoenzymes (TrxR and GPx) seems to be involved in the neurotoxicity associated with (PhTe)₂ exposure in adult mice.     

Technetium-99m-labeled ceftizoxime loaded long-circulating and pH-sensitive liposomes used to identify osteomyelitis

Osteomyelitis is an infectious disease located in the bone or bone marrow. Long-circulating and pH-sensitive liposomes containing a technetium-99m-labeled antibiotic, ceftizoxime, (SpHL-(99m)Tc-CF) were developed to identify osteomyelitis foci. Biodistribution studies and scintigraphic images of bone infection or non infection-bearing rats that had been treated with these liposomes were performed. A high accumulation in infectious foci and high values in the target-non target ratio could be observed. These results indicate the potential of SpHL-(99m)Tc-CF as a potential agent for the diagnosis of bone infections.     

Dissecting structure-function-stability relationships of a thermostable GH5-CBM3 cellulase from Bacillus subtilis 168

Cellulases participate in a number of biological events, such as plant cell wall remodelling, nematode parasitism and microbial carbon uptake. Their ability to depolymerize crystalline cellulose is of great biotechnological interest for environmentally compatible production of fuels from lignocellulosic biomass. However, industrial use of cellulases is somewhat limited by both their low catalytic efficiency and stability. In the present study, we conducted a detailed functional and structural characterization of the thermostable BsCel5A (Bacillus subtilis cellulase 5A), which consists of a GH5 (glycoside hydrolase 5) catalytic domain fused to a CBM3 (family 3 carbohydrate-binding module). NMR structural analysis revealed that the Bacillus CBM3 represents a new subfamily, which lacks the classical calcium-binding motif, and variations in NMR frequencies in the presence of cellopentaose showed the importance of polar residues in the carbohydrate interaction. Together with the catalytic domain, the CBM3 forms a large planar surface for cellulose recognition, which conducts the substrate in a proper conformation to the active site and increases enzymatic efficiency. Notably, the manganese ion was demonstrated to have a hyper-stabilizing effect on BsCel5A, and by using deletion constructs and X-ray crystallography we determined that this effect maps to a negatively charged motif located at the opposite face of the catalytic site.     

Role of SERK genes in plant environmental response

In plants, cell signaling connects the environmental input to the intracellular responses in plants. Exogenous signals play an important role in cell metabolism leading to growth and defense responses. Some of these stimuli induce anatomical and physiological modifications that are generally modulated by gene expression. SERK belongs to a small family of genes that code for a transmembrane protein involved in signal transduction and that have been strongly associated with somatic embryogenesis and apomixis in a number of plant species. Recent studies corroborate its role in somatic embryogenesis and suggest a broader range of functions in plant response to biotic and abiotic stimuli. This mini-review aims to present new data on SERK and discuss its involvement in plant development as well as in response to environmental stress.Key words: SERK, fungus tolerance, environmental stress, brassinosteroids, SAR     

Spatial dynamics and expanded vertical niche of blue sharks in oceanographic fronts reveal habitat targets for conservation

Dramatic population declines among species of pelagic shark as a result of overfishing have been reported, with some species now at a fraction of their historical biomass. Advanced telemetry techniques enable tracking of spatial dynamics and behaviour, providing fundamental information on habitat preferences of threatened species to aid conservation. We tracked movements of the highest pelagic fisheries by-catch species, the blue shark Prionace glauca, in the North-east Atlantic using pop-off satellite-linked archival tags to determine the degree of space use linked to habitat and to examine vertical niche. Overall, blue sharks moved south-west of tagging sites (English Channel; southern Portugal), exhibiting pronounced site fidelity correlated with localized productive frontal areas, with estimated space-use patterns being significantly different from that of random walks. Tracked female sharks displayed behavioural variability in diel depth preferences, both within and between individuals. Diel depth use ranged from normal DVM (nDVM; dawn descent, dusk ascent), to reverse DVM (rDVM; dawn ascent, dusk descent), to behavioural patterns where no diel differences were apparent. Results showed that blue sharks occupy some of the most productive marine zones for extended periods and structure diel activity patterns across multiple spatio-temporal scales in response to particular habitat types. In so doing, sharks occupied an extraordinarily broad vertical depth range for their size (1.0-2.0 m fork length), from the surface into the bathypelagic realm (max. dive depth, 1160 m). The space-use patterns of blue sharks indicated they spend much of the time in areas where pelagic longlining activities are often highest, and in depth zones where these fisheries particularly target other species, which could account for the rapid declines recently reported for blue sharks in many parts of the world's oceans. Our results provide habitat targets for blue shark conservation that may also be relevant to other pelagic species.     

Profile of Central and Effector Memory T Cells in the Progression of Chronic Human Chagas Disease

Background

Chronic Chagas disease presents several different clinical manifestations ranging from asymptomatic to severe cardiac and/or digestive clinical forms. Several studies have demonstrated that immunoregulatory mechanisms are important processes for the control of the intense immune activity observed in the chronic phase. T cells play a critical role in parasite specific and non-specific immune response elicited by the host against Trypanosoma cruzi. Specifically, memory T cells, which are basically classified as central and effector memory cells, might have a distinct migratory activity, role and function during the human Chagas disease.

Methodology/Principal Findings

Based on the hypothesis that the disease severity in humans is correlated to the quality of immune responses against T. cruzi, we evaluated the memory profile of peripheral CD4⁺ and CD8⁺ T lymphocytes as well as its cytokine secretion before and after in vitro antigenic stimulation. We evaluated cellular response from non-infected individuals (NI), patients with indeterminate (IND) or cardiac (CARD) clinical forms of Chagas disease. The expression of CD45RA, CD45RO and CCR7 surface molecules was determined on CD4⁺ and CD8⁺ T lymphocytes; the pattern of intracellular cytokines (IFN-γ, IL-10) synthesized by naive and memory cells was determined by flow cytometry. Our results revealed that IND and CARD patients have relatively lower percentages of naive (CD45RA^high) CD4⁺ and CD8⁺ T cells. However, statistical analysis of ex-vivo profiles of CD4⁺ T cells showed that IND have lower percentage of CD45RA^high in relation to non-infected individuals, but not in relation to CARD. Elevated percentages of memory (CD45RO^high) CD4⁺ T cells were also demonstrated in infected individuals, although statistically significant differences were only observed between IND and NI groups. Furthermore, when we analyzed the profile of secreted cytokines, we observed that CARD patients presented a significantly higher percentage of CD8⁺CD45RA^high IFN-γ-producing cells in control cultures and after antigen pulsing with soluble epimastigote antigens.

Conclusions

Based on a correlation between the frequency of IFN-γ producing CD8+ T cells in the T cell memory compartment and the chronic chagasic myocarditis, we propose that memory T cells can be involved in the induction of the development of the severe clinical forms of the Chagas disease by mechanisms modulated by IFN-γ. Furthermore, we showed that individuals from IND group presented more T_CM CD4⁺ T cells, which may induce a regulatory mechanism to protect the host against the exacerbated inflammatory response elicited by the infection.     

Organization of highly repeated sequences in surface-spread pachytene chromosomes of rye.

A method of preparing two-dimensional surface spreads of plant synaptonemal complexes (SCs) associated with fluorescence in situ hybridization (FISH) has been applied to analyze the location and organization of five different highly repeated DNA sequences in rye. Our observations indicate that, depending on the type of sequence, the chromatin displays different types of organization. Telomeric sequences were seen tightly associated with the SC while other repetitive DNA sequences were found to form loops that are associated with SCs only at their bases. On the contrary, the FISH signal of a centromeric satellite had a granular appearance, reflecting that the hybridization occurs only with parts of the chromatin loops.     

Evaluation of live attenuated influenza a virus h6 vaccines in mice and ferrets

Avian influenza A virus A/teal/HK/W312/97 (H6N1) possesses seven gene segments that are highly homologous to those of highly pathogenic human influenza H5N1 viruses, suggesting that a W312-like H6N1 virus might have been involved in the generation of the A/HK/97 H5N1 viruses. The continuous circulation and reassortment of influenza H6 subtype viruses in birds highlight the need to develop an H6 vaccine to prevent potential influenza pandemics caused by the H6 viruses. Based on the serum antibody cross-reactivity data obtained from 14 different H6 viruses from Eurasian and North American lineages, A/duck/HK/182/77, A/teal/HK/W312/97, and A/mallard/Alberta/89/85 were selected to produce live attenuated H6 candidate vaccines. Each of the H6 vaccine strains is a 6:2 reassortant ca virus containing HA and NA gene segments from an H6 virus and the six internal gene segments from cold-adapted A/Ann Arbor/6/60 (AA ca), the master donor virus that is used to make live attenuated influenza virus FluMist (intranasal) vaccine. All three H6 vaccine candidates exhibited phenotypic properties of temperature sensitivity (ts), ca, and attenuation (att) conferred by the internal gene segments from AA ca. Intranasal administration of a single dose of the three H6 ca vaccine viruses induced neutralizing antibodies in mice and ferrets and fully protected mice and ferrets from homologous wild-type (wt) virus challenge. Among the three H6 vaccine candidates, the A/teal/HK/W312/97 ca virus provided the broadest cross-protection against challenge with three antigenically distinct H6 wt viruses. These data support the rationale for further evaluating the A/teal/HK/W312/97 ca vaccine in humans.