Development of a novel anti-biofilm peptide derived from profilin of Spodoptera frugiperda

Abstract

Candida yeast infections are the fourth leading cause of death worldwide. Peptides with antimicrobial activity are a promising alternative treatment for such infections. Here, the antifungal activity of a new antimicrobial peptide—PEP-IA18—was evaluated against Candida species. PEP-IA18 was designed from the primary sequence of profilin, a protein from Spodoptera frugiperda, and displayed potent activity against Candida albicans and Candida tropicalis, showing a minimum inhibitory concentration (MIC) of 2.5?µM. Furthermore, the mechanism of action of PEP-IA18 involved interaction with the cell membrane (ergosterol complexation). Treatment at MIC and/or 10?×?MIC significantly reduced biofilm formation and viability. PEP-IA18 showed low toxicity toward human fibroblasts and only revealed hemolytic activity at high concentrations. Thus, PEP-IA18 exhibited antifungal and anti-biofilm properties with potential applicability in the treatment of infections caused by Candida species.     

Water deficit tolerance in sugarcane is dependent on the accumulation of sugar in the leaf

Sugarcane productivity is severely affected by the occurrence of water deficit in the field, causing inhibition of growth and sugar production. Evaluating physiological responses of sugarcane under water deficit conditions is essential to understand physiological variables responsible for reaching homeostasis. Therefore, we analysed physiological traits of two sugarcane genotypes, RB835486 (Tolerant) and RB855453 (Susceptible), under water deficit conditions: well-watered (WW-Control), water deficit (WD) and rewatered (RW). The physiological response was evaluated using linear regression and multivariate analysis. Some characteristics such as water potential in leaves, photosynthesis, chlorophyll fluorescence, chlorophyll index, sucrose and starch contents did not show differences between the genotypes under water deficit conditions. However, the tolerant genotype showed increased reducing sugars content in the leaves, whereas the susceptible genotype had increased non-photochemical quenching (qN). After rewatering, the susceptible sugarcane genotype showed higher electron transport rate (ETR) and efficiency of PSII (Y). Multivariate analysis revealed that non-photochemical quenching and reducing sugars in the leaves were physiological variables responsible for reaching homestasis under water deficit conditions. Therefore, the reducing sugars concentration should be considered a physiological variable responsible for the adjustment made by the tolerant sugarcane genotype when submitted to water deficit.     

The interplay between local and landscape scales on the density of pond-dwelling anurans in subtropical grasslands

We investigated the role of local and landscape environmental variables on anurans density classified as habitat specialists and generalists in grassland landscapes, known as South Brazilian grasslands (SBG). In this region, we surveyed 187 ponds distributed over 40 landscape sampling units. For each pond, 31 local environmental variables were measured. Each landscape sampling unit was embedded within a larger regional sampling unit with different landscape properties. For each landscape and regional sampling units, 16 landscape metrics were extracted from a land cover and use map. We recorded 35 species, eleven of which are specialists in the SBG. The specialists were affected by 11 local and 2 landscape environmental variables, while generalists were affected by 14 local and one landscape environmental variable. Thus, specialists and generalists presented different relationships with local and landscape variables, but in general local variables had a greater influence on the density of anurans than the landscape variables. However, the landscape indirectly influenced local variables because higher quality ponds were in landscapes with higher percentages of natural habitat. In conclusion, reproductive sites with higher local quality and located within landscapes with higher percentages of natural grasslands are essential to conserve anurans in this habitat. Effective conservation of such sites would benefit from further studies that assess effects of land use and biotic integrity of ponds, which can help to determine (a) the relative effects of local habitat quality of ponds and (b) the effectiveness of protecting ponds and their local surroundings for anuran conservation in SBG. Abstract in Portuguese is available with online material.     

Highways are a threat for giant armadillos that underpasses can mitigate

We report 24 records of giant armadillo roadkill on Brazilian highways in the Cerrado, Pantanal and Amazon biomes illustrating that highways are a threat to this species. However, we also documented the species using underpasses, demonstrating that these structures could help to reduce the risk of roadkill for giant armadillos.     

Relationship between epipelon,epiphyton and phytoplankton in two limnological phases in a shallow tropical reservoir with high Nymphaea coverage

Macrophytes and phytoplankton are recognized as having roles in determining alternative stable states in shallow lakes and reservoirs, while the role of periphyton has been poorly investigated. Temporal and spatial variation of phytoplankton, epipelon and epiphyton was examined in a shallow reservoir with high abundance of aquatic macrophytes. The relationships between algae communities and abiotic factors, macrophyte coverage and zooplankton density were also analyzed. Monthly sampling was performed in three zones of the depth gradient of the reservoir. Two phases of algal dominance were found: a phytoplankton phase and epipelon phase. The phase of phytoplankton dominance was characterized by high macrophyte coverage. Rotifera was the dominant zooplankton group in all the zones. Flagellate algae were dominant in phytoplankton, epipelon and epiphyton. Macrophyte coverage was found to be a predictor for algal biomass. Changes in biomass and species composition were associated with macrophyte cover variation, mainly the Nymphaea. In addition to the abiotic factors, the macrophyte coverage was a determining factor for changes to the algal community, contributing to the alternation between dominance phases of phytoplankton and epipelon. The macrophyte–phytoplankton–periphyton relationship needs to be further known in shallow reservoirs, especially the role of epipelon as an alternate stable state.

     

Trophic ecology and metabolism of two species of nonnative freshwater stingray (Chondrichthyes: Potamotrygonidae)

The stingrays Potamotrygon amandae and Potamotrygon falkneri are nonnative species established in the Upper Paraná basin. Although they are widely distributed, few studies on their diets or respective metabolic responses exist. Therefore, the aim was to evaluate the dietary composition, trophic niche breadth and lipid/protein concentrations in muscle and hepatic tissues of these two species, as well as the interrelationships between them. The individuals were collected in two areas on the Upper Paraná River. The stomachs and samples of muscle and liver tissues were taken for analysis. A broad dietary spectrum was observed for both species, along with differences in dietary composition, with a higher consumption of detritus by P. amandae and Baetidae by P. falkneri. No differences were observed in the trophic niche breadth. Regarding the metabolic variables, differences were only found in the hepatic protein, with a higher content observed in P. falkneri. A significant positive correlation was observed between items of animal origin and detritus with muscle protein for this species. This shows that such feeding habits, which are characteristic of a generalist, influenced the metabolism of the species and possibly contributed to the successful adjustment of the species to new habitats in the Upper Paraná River.

     

Traffic of Leukocytes and Cytokine Up-regulation in the Central Nervous System in a Murine Model of Neuroparacoccidioidomycosis

Background

Paracoccidioidomycosis is the most important systemic mycosis in South America. In the last decades, it was observed that central nervous system involvement is frequent, occurring in 12.5 % of the cases. The aim of this study was to report the early inflammatory changes associated with an experimental model of neuroparacoccidioidomycosis (NPCM).

Methods

C57BL/6 mice were infected by intracranial route with 10⁶ yeast cells of PB18 strain of Paracoccidioides brasiliensis. Leukocyte–endothelium interactions were assessed by intravital microscopy 1, 2, 4, and 8 weeks post-infection (p.i.). Chemokine/cytokine levels in the brain and histopathological changes were assessed 4 and 8 weeks p.i..

Results

Intravital microscopy analysis revealed a progressive increase in leukocyte recruitment in the vessels of pia mater with a peak 4 weeks p.i. The chemokine CXCL9 was increased at 4 and 8 weeks p.i., while CCL2, CCL3, and CCL5 were increased at 8 weeks p.i. Histopathological analysis revealed the infiltration of inflammatory cells and the development of progressive granulomatous meningoencephalitis. CCL3 levels correlated with clinical manifestations of disease, as measured by the SHIRPA battery.

Conclusions

The experimental model of NPCM showed increased leukocyte recruitment associated with increased expression of chemokines and nervous tissue inflammation which correlated with clinical manifestations of disease.     

Wavelength dependence of biological damage induced by UV radiation on bacteria

The biological effects of UV radiation of different wavelengths (UVA, UVB and UVC) were assessed in nine bacterial isolates displaying different UV sensitivities. Biological effects (survival and activity) and molecular markers of oxidative stress [DNA strand breakage (DSB), generation of reactive oxygen species (ROS), oxidative damage to proteins and lipids, and the activity of antioxidant enzymes catalase and superoxide dismutase] were quantified and statistically analyzed in order to identify the major determinants of cell inactivation under the different spectral regions. Survival and activity followed a clear wavelength dependence, being highest under UVA and lowest under UVC. The generation of ROS, as well as protein and lipid oxidation, followed the same pattern. DNA damage (DSB) showed the inverse trend. Multiple stepwise regression analysis revealed that survival under UVA, UVB and UVC wavelengths was best explained by DSB, oxidative damage to lipids, and intracellular ROS levels, respectively.