Adipose tissue proadipogenic redox changes in obesity

The role of inflammation and oxidative stress in the development of obesity and associated metabolic disorders is under debate. We investigated the redox metabolism in a non-diabetic obesity model, i.e. 11-week-old obese Zucker rats. Antioxidant enzyme activities, lipophilic antioxidant (alpha-tocopherol, coenzymes Q) and hydrophilic antioxidant (glutathione, vitamin C) contents and their redox state (% oxidized form), were studied in inguinal white fat and compared with blood and liver. The adipose tissues of obese animals showed a specific higher content of hydrophilic molecules in a lower redox state than those of lean animals, which were associated with lower lipophilic molecule content and lipid peroxidation. Conversely and as expected, glutathione content decreased and its redox state increased in adipose tissues of rats subjected to lipopolysaccharide-induced systemic oxidative stress. In these in vivo models, oxidative stress and obesity thus had opposite effects on adipose tissue redox state. Moreover, the increase in glutathione content and the decrease of its redox state by antioxidant treatment promoted in vitro the accumulation of triglycerides in preadipocytes. Taken together and contrary to the emergent view, our results suggest that obesity is associated with an intracellular reduced redox state that promotes on its own the development of a deleterious proadipogenic process.     

Cytomegalovirus Infection in Inflammatory Bowel Disease Is Not Associated with Worsening of Intestinal Inflammatory Activity

Background

Cytomegalovirus is highly prevalent virus and usually occurs in immunocompromised patients. The pathophysiology and treatment of inflammatory bowel disease often induce a state of immunosuppression. Because this, there are still doubts and controversies about the relationship between inflammatory bowel disease and cytomegalovirus.

Aim

Evaluate the frequency of cytomegalovirus in patients with inflammatory bowel disease and identify correlations.

Methods

Patients with inflammatory bowel disease underwent an interview, review of records and collection of blood and fecal samples. The search for cytomegalovirus was performed by IgG and IgM blood serology, by real-time PCR in the blood and by qualitative PCR in feces. Results were correlated with red blood cell levels, C-reactive protein levels, erythrocyte sedimentation rates and fecal calprotectin levels for each patient.

Results

Among the 400 eligible patients, 249 had Crohn''s disease, and 151 had ulcerative colitis. In the group of Crohn''s disease, 67 of the patients had moderate or severe disease, but 126 patients presented with active disease, based on the evaluation of the fecal calprotectin. In patients with ulcerative colitis, only 21 patients had moderate disease, but 76 patients presented with active disease, based on the evaluation of the fecal calprotectin. A large majority of patients had positive CMV IgG. Overall, 10 patients had positive CMV IgM, and 9 patients had a positive qualitative detection of CMV DNA by PCR in the feces. All 400 patients returned negative results after the quantitative detection of CMV DNA in blood by real-time PCR. Analyzing the 19 patients with active infections, we only found that such an association occurred with the use of combined therapy (anti-TNF-alpha + azathioprine)

Conclusion

The findings show that latent cytomegalovirus infections are frequent and active cytomegalovirus infection is rare. We did not find any association between an active infection of CMV and inflammatory bowel disease activity.     

Photolabeling study of the ligand binding domain of natriuretic peptide receptor A: development of a model

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are loop-shaped peptidic hormones that have multiple actions on body fluid homeostasis. Their physiological effects are mediated through the activation of their receptor, natriuretic peptide receptor A (NPRA). This receptor is a member of the membrane guanylyl cyclase family and catalyzes cyclic guanosine monophosphate (cGMP) production following its activation. To map the binding site of human NPRA, we applied the methionine proximity assay method to this receptor. We photolabeled NPRA mutants, presenting a single methionine in the binding domain of the receptor, and used benzoylphenylalanine- (Bpa-) substituted peptides at positions 0, 3, 18, 26, and 28 of the ligand. We identified that the N-terminus of the peptide is interacting with the region between Asp(177) and Val(183) of the receptor. Arg(3) is interacting in the vicinity of Phe(172). Leu(18) binds close to Val(116). Phe(26) binds in the vicinity of His(195), and the C-terminal Tyr(28) is located close to Met(173). We next proceeded with photolabeling of a dual Bpa-substituted peptide and showed that the N-terminus and Leu(18) interact with opposite receptor subunits. On the basis of our results, a molecular model of peptide-bound NPRA was developed by homology modeling with the C-type natriuretic peptide- (CNP-) bound natriuretic peptide receptor C (NPRC) crystal structure. The model has been validated by molecular dynamics simulations. Our work provides a rational basis for interpreting and predicting natriuretic peptide binding to the human NPRA.     

The Population Decline and Extinction of Darwin’s Frogs

Darwin’s frogs (Rhinoderma darwinii and R. rufum) are two species of mouth-brooding frogs from Chile and Argentina. Here, we present evidence on the extent of declines, current distribution and conservation status of Rhinoderma spp.; including information on abundance, habitat and threats to extant Darwin’s frog populations. All known archived Rhinoderma specimens were examined in museums in North America, Europe and South America. Extensive surveys were carried out throughout the historical ranges of R. rufum and R. darwinii from 2008 to 2012. Literature review and location data of 2,244 archived specimens were used to develop historical distribution maps for Rhinoderma spp. Based on records of sightings, optimal linear estimation was used to estimate whether R. rufum can be considered extinct. No extant R. rufum was found and our modelling inferred that this species became extinct in 1982 (95% CI, 1980–2000). Rhinoderma darwinii was found in 36 sites. All populations were within native forest and abundance was highest in Chiloé Island, when compared with Coast, Andes and South populations. Estimated population size and density (five populations) averaged 33.2 frogs/population (range, 10.2–56.3) and 14.9 frogs/100 m² (range, 5.3–74.1), respectively. Our results provide further evidence that R. rufum is extinct and indicate that R. darwinii has declined to a much greater degree than previously recognised. Although this species can still be found across a large part of its historical range, remaining populations are small and severely fragmented. Conservation efforts for R. darwinii should be stepped up and the species re-classified as Endangered.     

An example of molecular co-evolution: reactive oxygen species (ROS) and ROS scavenger levels in Schistosoma mansoni/Biomphalaria glabrata interactions

The co-evolution between hosts and parasites involves huge reciprocal selective pressures on both protagonists. However, relatively few reports have evaluated the impact of these reciprocal pressures on the molecular determinants at the core of the relevant interaction, such as the factors influencing parasitic virulence and host resistance. Here, we address this question in a host-parasite model that allows co-evolution to be monitored in the field: the interaction between the mollusc, Biomphalaria glabrata, and its trematode parasite, Schistosoma mansoni. Reactive oxygen species (ROS) produced by the haemocytes of B. glabrata are known to play a crucial role in killing S. mansoni. Therefore, the parasite must defend itself against oxidative damage caused by ROS using ROS scavengers in order to survive. In this context, ROS and ROS scavengers are involved in a co-evolutionary arms race, and their respective production levels by sympatric host and parasite could be expected to be closely related. Here, we test this hypothesis by comparing host oxidant and parasite antioxidant capabilities between two S. mansoni/B. glabrata populations that have co-evolved independently. As expected, our findings show a clear link between the oxidant and antioxidant levels, presumably resulting from sympatric co-evolution. We believe this work provides the first supporting evidence of the Red Queen Hypothesis of reciprocal evolution for functional traits at the field-level in a model involving a host and a eukaryotic parasite.     

Fossil psychodoid flies and their relation to parasitic diseases

Psychodid sand flies are blood-sucking fly vectors of several parasitic diseases. The oldest definitive record of this group is from the Lower Cretaceous amber of Lebanon (circa-135 to -125 My), but the high diversity within this group supports the idea that the psychodoids originated much earlier in history. The palaeontology demonstrates that the Lower Creataceous representatives of the different subfamilies of Psychodidae had similar morphology and were blood-feeders, which supports Hennig's hypothesis on the ground plan structure of this family. Historical relationship between sand flies and diseases is unclear up to the present time, but this relationship could be as old as the origin of psychodoids because of the blood-feeding life mode.     

Synthesis, biological evaluation and mechanistic studies of totarol amino alcohol derivatives as potential antimalarial agents

Herein we report on the semisynthesis and biological evaluation of β-amino alcohol derivatives of the natural product totarol and other simple aromatic systems. All β-amino alcohol derivatives of totarol exhibited higher antiplasmodial activity than totarol [IC(50): 11.69 μM (K1, chloroquine and multi-drug resistant strain), and 11.78 μM (D10, chloroquine sensitive strain)]-12e was the most active [IC(50): 0.63 μM (K1), and 0.61 μM (D10)]. The phenyl and naphthyl β-amino alcohol derivatives were much less active than their corresponding totarol equivalents. The majority of the β-amino alcohol derivatives of totarol were more active against K1 than the D10 strains of Plasmodium falciparum, a trend similar to the inverse relationship observed with the established aryl-amino alcohol antimalarial mefloquine. Selected compounds were shown to affect erythrocyte morphology, inhibit erythrocyte invasion and trigger CQ accumulation.     

Disruption of SCO5461 gene coding for a mono-ADP-ribosyltransferase enzyme produces a conditional pleiotropic phenotype affecting morphological differentiation and antibiotic production in Streptomyces coelicolor

The SCO5461 gene of Streptomyces coelicolor A3(2) codes for an ADP-ribosyltransferase enzyme that is predicted to be a transmembrane protein with an extracellular catalytic domain. PCR-targeted disruption of the gene resulted in a mutant that differentiated normally on complex SFM medium; however, morphological differentiation in minimal medium was significantly delayed and this phenotype was even more pronounced on osmotically enhanced minimal medium. The mutant did not sporulate when it was grown on R5 medium, however the normal morphological differentiation was restored when the strain was cultivated beside the wild-type S. coelicolor M145 strain. Comparison of the pattern of ADP-ribosylated proteins showed a difference between the mutant and the wild type, fewer modified proteins were present in the cellular crude extract of the mutant strain. These results support our previous suggestions that protein ADP-ribosylation is involved in the regulation of differentiation and antibiotic production and secretion in Streptomyces.