Cubebin and derivatives as inhibitors of mitochondrial complex I. Proposed interaction with subunit B8

The effects on mitochondrial respiration and complex I NADH oxidase activity of cubebin and derivatives were evaluated. The compounds inhibited the state 3 glutamate/malate-supported respiration of hamster liver mitochondria with IC₅₀ values ranging from 12.16 to 83.96 μM. NADH oxidase reaction was evaluated in submitochondrial particles. The compounds also inhibited this activity, showing the same order of potency observed for effects on state 3 respiration, as well as a tendency towards a non-competitive type of inhibition (K_I values ranging from 0.62 to 16.1 μM). A potential binding mode of these compounds with complex I subunit B8, assessed by docking calculations, is proposed.     

Accessory spleen in cetaceans and its relevance as a secondary lymphoid organ

The objective was to determine the prevalence of accessory spleens in cetaceans stranded on the north and northeastern coasts of Brazil and to describe their macroscopic and microscopic characteristics, thereby providing insights into the contribution of these structures to the immune system of cetaceans. Sixty-three Odontocetes and Mysticetes (total of 14 species), male and female, ranging from calves to adults, stranded from 2009 to 2013 on the Brazilian north and northeastern coasts, were evaluated. Accessory spleens were present in 38 animals (60.3 %), with 1–14 accessory spleens per animal. Their location varied among species, ranging from firmly adherent to the spleen, to the large curvature of the first stomach or both. The presence of these structures was apparently not related to age or sex. However, there was a higher prevalence in animals with a greater body size and known to make deeper dives. Both primary and accessory spleens had similar macroscopic morphology with no demarcation between cortex and medulla. Both primary and accessory spleens had similar histological characteristics. Furthermore, it was noteworthy that germinal centers became more discrete and reduced in number with increasing age. In conclusion, we inferred that accessory spleens may be an additional mechanism for adaptation to diving and that they have a complementary reservoir function and thus can be considered compensatory lymphoid organs to splenic activity.     

Effect of fires on soil nutrient availability in an open savanna in Central Brazil

Fire is common in savannas but its effects on soil are poorly understood. We analyzed long-term effects of fire on surface soil of an open Brazilian savanna (campo sujo) in plots submitted to different fire regimes during 18 years. The five fire regimes were: unburned, quadrennial fires in middle dry season, and biennial fires in early, middle or late dry season. Soil was collected during the wet and the middle dry season of 2008, and analyzed for pH, organic matter, total N, potential acidity, exchangeable cations and available P, S, Mn, Cu, Zn and Fe. We applied multivariate analysis to search for patterns related to fire regimes, and to local climate, fuel, and fire behavior. Spearman test was used to establish correlations between soil variables and the multivariate analysis gradient structure. Seasonal differences were tested using t-test. We found evidence of long-term fire effects: the unburned plot was segregated mainly by lower soil pH; the quadrennial plot was also segregated by lower soil pH and higher amount of exchangeable cations; the time of burning during the dry season in biennial plots did not significantly affect soil availability of nutrients. Differences in elements amounts due to the season of soil sampling (wet or dry) were higher than due to the effect of fires. Higher availability of nutrients in the soil during the wet season was probably related to higher nutrient inputs via rainfall and higher microbial activity.     

Respiratory allergy to Blomia tropicalis: Immune response in four syngeneic mouse strains and assessment of a low allergen-dose,short-term experimental model

Background

The dust mite Blomia tropicalis is an important source of aeroallergens in tropical areas. Although a mouse model for B. tropicalis extract (BtE)-induced asthma has been described, no study comparing different mouse strains in this asthma model has been reported. The relevance and reproducibility of experimental animal models of allergy depends on the genetic background of the animal, the molecular composition of the allergen and the experimental protocol.

Objectives

This work had two objectives. The first was to study the anti-B. tropicalis allergic responses in different mouse strains using a short-term model of respiratory allergy to BtE. This study included the comparison of the allergic responses elicited by BtE with those elicited by ovalbumin in mice of the strain that responded better to BtE sensitization. The second objective was to investigate whether the best responder mouse strain could be used in an experimental model of allergy employing relatively low BtE doses.

Methods

Groups of mice of four different syngeneic strains were sensitized subcutaneously with 100 μg of BtE on days 0 and 7 and challenged four times intranasally, at days 8, 10, 12, and 14, with 10 μg of BtE. A/J mice, that were the best responders to BtE sensitization, were used to compare the B. tropicalis-specific asthma experimental model with the conventional experimental model of ovalbumin (OVA)-specific asthma. A/J mice were also sensitized with a lower dose of BtE.

Results

Mice of all strains had lung inflammatory-cell infiltration and increased levels of anti-BtE IgE antibodies, but these responses were significantly more intense in A/J mice than in CBA/J, BALB/c or C57BL/6J mice. Immunization of A/J mice with BtE induced a more intense airway eosinophil influx, higher levels of total IgE, similar airway hyperreactivity to methacholine but less intense mucous production, and lower levels of specific IgE, IgG1 and IgG2 antibodies than sensitization with OVA. Finally, immunization with a relatively low BtE dose (10 μg per subcutaneous injection per mouse) was able to sensitize A/J mice, which were the best responders to high-dose BtE immunization, for the development of allergy-associated immune and lung inflammatory responses.

Conclusions

The described short-term model of BtE-induced allergic lung disease is reproducible in different syngeneic mouse strains, and mice of the A/J strain was the most responsive to it. In addition, it was shown that OVA and BtE induce quantitatively different immune responses in A/J mice and that the experimental model can be set up with low amounts of BtE.     

Diversity of flies (Diptera: Tephritidae and Lonchaeidae) in organic citrus orchards in the vale do Rio Caí, Rio Grande do Sul, southern Brazil

This study was carried out in the Counties of Montenegro and Pareci Novo located in the region of the Vale do Rio Cai, Rio Grande do Sul, Southern Brazil, aiming to determine the fruit fly species of Tephritidae and Lonchaeidae that occur in organic orchards of sweet orange [Citrus sinensis (L.) Osb.] cultivar Céu, and Murcott tangor (Citrus reticulata Blanco x C. sinensis), during the fruit ripening stages in 2003 and 2004. Eight McPhail traps baited with integral grape juice diluted to 25% were installed in four orchards, two in each citrus species. The traps were checked weekly, when the baits were changed, the flies separated and preserved in 70% ethyl alcohol. Fruits were also sampled from the orchards, placed in containers with damp soil and closed with a mesh. The tephritid flies represented 86.2% of all captured flies in the four orchards during both years. Five Tephritidae species were captured from traps: Anastrepha fraterculus (Wiedemann), Anastrepha grandis (Macquart), Anastrepha pseudoparallela (Loew), Anastrepha dissimilis Stone and Ceratitis capitata (Wiedemann). The captured species of Lonchaeidae were: Neosilba zadolicha McAlpine & Steyskal, Neosilba n.sp.3, Neosilba sp. and Lonchaea sp. Anastrepha fraterculus was found in 99% of the fruit samples, both in 'Céu' orange and 'Murcott' tangor, and Neosilba n.sp.3 were only obtained from 'Murcott' tangor fruits.     

Small molecule inhibitors of lysozyme amyloid aggregation

Protein amyloid aggregation is associated with a number of important human pathologies, but the precise mechanisms underlying the toxicity of amyloid aggregates are still incompletely understood. In this context, drugs capable of blocking or interfering with the aggregation of amyloidogenic proteins should be considered in strategies aimed at the development of novel therapeutic agents. Human lysozyme variants have been shown to form massive amyloid deposits in the livers and kidneys of individuals affected by hereditary systemic amyloidosis. Currently, there are no clinical treatments available to prevent or reverse formation of such amyloid deposits. We have recently described a number of di- and trisubstituted aromatic compounds that block the formation of soluble oligomers and amyloid fibrils of the β-amyloid peptide (Aβ) and protect hippocampal neurons in culture from Aβ-induced toxicity. Here, we show that some of those compounds inhibit the formation and disrupt preformed amyloid fibrils from both human and hen egg white lysozyme. These results suggest that these small molecule compounds may serve as prototypes for the development of drugs for the prevention or treatment of different types of amyloidoses.     

Prospecting candidate SNPs for backfat in Canchim beef cattle

Canchim is a composite cattle breed developed in Brazil for beef production. One of the breeding objectives is to increase fat deposition. QTLs for fat thickness and/or marbling have been reported on BTA4 and BTA14. The IGFBP3 and DDEF1 genes, mapped to BTA4 and BTA14, respectively, affect adipogenesis. We looked for SNPs in the IGFBP3 and DDEF1 genes that could be associated with backfat thickness in Canchim beef cattle. For SNP identification, sires with the highest accuracy were ranked according to expected breeding value for fat thickness; the 12 extremes (six sires with the highest and six with the lowest expected breeding value for the trait) were chosen. Six regions of the IGFBP3 and 14 regions of the DDEF1 were sequenced using the Sanger method. Nine SNPs were identified in IGFBP3 and 76 in the DDEF1. After an initial analysis, two SNPs were selected to be genotyped for the whole population; these were DDEF1g.279401A>G and IGFBP3c.4394T>C(Trp>Arg). We found a significant effect (P ≤ 0.05) of allele substitution on backfat thickness; however, the IGFBP3 SNP did not significantly affect this trait.     

Multiple stages of detergent-erythrocyte membrane interaction--a spin label study

The various stages of the interaction between the detergent Triton X-100 (TTX-100) and membranes of whole red blood cells (RBC) were investigated in a broad range of detergent concentrations. The interaction was monitored by RBC hemolysis-assessed by release of intracellular hemoglobin (Hb) and inorganic phosphate-and by analysis of EPR spectra of a fatty acid spin probe intercalated in whole RBC suspensions, as well as pellets and supernatants obtained upon centrifugation of detergent-treated cells. Hemolysis finished at ca. 0.9mM TTX-100. Spectral analysis and calculation of order parameters (S) indicated that a complex sequence of events takes place, and allowed the characterization of various structures formed in the different stages of detergent-membrane interaction. Upon reaching the end of cell lysis, essentially no pellet was detected, the remaining EPR signal being found almost entirely in the supernatants. Calculated order parameters revealed that whole RBC suspensions, pellets, and supernatants possessed a similar degree of molecular packing, which decreased to a small extent up to 2.5mM detergent. Between 3.2 and 10mM TTX-100, a steep decrease in S was observed for both whole RBC suspensions and supernatants. Above 10mM detergent, S decreased in a less pronounced manner and the EPR spectra approached that of pure TTX-100 micelles. The data were interpreted in terms of the following events: at the lower detergent concentrations, an increase in membrane permeability occurs; the end of hemolysis coincides with the lack of pellet upon centrifugation. Up to 2.5mM TTX-100 the supernatants consist of a (very likely) heterogeneous population of membrane fragments with molecular packing similar to that of whole cells. As the detergent concentration increases, mixed micelles are formed containing lipid and/or protein, approaching the packing found in pure TTX-100 micelles. This analysis is in agreement with the models proposed by Lasch (Biochim. Biophys Acta 1241 (1995) 269-292) and by Le Maire and coworkers (Biochim. Biophys. Acta 1508 (2000) 86-111).