No abstract

Rhynchophorus palmarum Linnaeus is an agricultural pest that affects various palm crops, including coconut (Cocos nucifera) plantations which are prominent in the economy of Northeastern Brazil. Characterization of the intestinal microbiota of R. palmarum, as well as elucidation of aspects related to the biochemistry and physiology of the insect's digestion, is essential for intervention in specific metabolic processes as a form of pest control. Thus, this study aimed to characterize the intestinal microbiota of R. palmarum and investigate its ability to degrade cellulosic substrates, to explore new biological control measures. Intestinal dissection of eight adult R. palmarum insects was performed in a laminar flow chamber, and the intestines were homogenized in sterile phosphate‐buffered saline solution. Subsequently, serial dilution aliquots of these solutions were spread on nutritive agar plates for the isolation of bacteria and fungi. The microorganisms were identified by matrix‐assisted laser desorption/ionization with a time‐of‐flight mass spectrometry and evaluated for their ability to degrade cellulose. Fourteen bacterial genera (Acinetobacter, Alcaligenes, Arthrobacter, Bacillus, Citrobacter, Enterococcus, Kerstersia, Lactococcus, Micrococcus, Proteus, Providencia, Pseudomonas, Serratia, and Staphylococcus) and two fungal genera (Candida and Saccharomyces)—assigned to the Firmicutes, Actinobacteria, Proteobacteria, and Ascomycota phyla—were identified. The cellulolytic activity was exhibited by six bacterial and one fungal species; of these, Bacillus cereus demonstrated the highest enzyme synthesis (enzymatic index = 4.6). This is the first study characterizing the R. palmarum intestinal microbiota, opening new perspectives for the development of strategies for the biological control of this insect.

Dimorphic fungi of the Paracoccidioides genus are the causative agents of paracoccidioidomycosis (PCM), an endemic disease in Latin America with a high incidence in Brazil. This pathogen presents as infective mycelium at 25 °C in the soil, reverting to its pathogenic form when inhaled by the mammalian host (37 °C). Among these dimorphic fungal species, dimorphism regulating histidine kinase (Drk1) plays an essential role in the morphological transition. These kinases are present in bacteria and fungi but absent in mammalian cells and are important virulence and cellular survival regulators. Hence, the purpose of this study was to investigate the role of PbDrk1 in the cell wall modulation of P. brasiliensis. We observed that PbDrk1 participates in fungal resistance to different cell wall-disturbing agents by reducing viability after treatment with iDrk1. To verify the role of PbDRK1 in cell wall morphogenesis, qPCR results showed that samples previously exposed to iDrk1 presented higher expression levels of several genes related to cell wall modulation. One of them was FKS1, a β-glucan synthase that showed a 3.6-fold increase. Furthermore, confocal microscopy analysis and flow cytometry showed higher β-glucan exposure on the cell surface of P. brasiliensis after incubation with iDrk1. Accordingly, through phagocytosis assays, a significantly higher phagocytic index was observed in yeasts treated with iDrk1 than the control group, demonstrating the role of PbDrk1 in cell wall modulation, which then becomes a relevant target to be investigated. In parallel, the immune response profile showed increased levels of proinflammatory cytokines. Finally, our data strongly suggest that PbDrk1 modulates cell wall component expression, among which we can identify β-glucan. Understanding this signalling pathway may be of great value for identifying targets of antifungal molecular activity since HKs are not present in mammals.

Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Latin America and is caused by fungi from the Paracoccidioides genus. The infection begins after inhalation of the fungal propagules and their thermo-dimorphic shift to yeast form. Proteases play an important role in the host invasion process and immune modulation in many pathogenic microorganisms. Aspartyl proteases are virulence factors in many human fungal pathogens that play an important role in the host invasion process morphogenesis, cellular function, immunity, and nutrition. In the present study, we characterized the modulation of acid proteases from Paracoccidioides brasiliensis. We detected four aspartyl proteases in P. brasiliensis with high homology to aspartic protease from Saccharomyces cerevisiae Pep4. Furthermore, we demonstrated that Pepstatin A can inhibit dimorphic switching (mycelium→yeast) in P. brasiliensis. In addition, these genes were modulated during thermo-dimorphism (M→Y transition) in the presence or absence of carbon and nitrogen sources and during growth at pH 4 during 24 and 48 h. We also observed that P. brasiliensis increase the secretion of aspartic proteases when cultivated at pH 4, and these acid proteases cleave BSA, collagen, and hemoglobin. These data suggest that aspartyl proteases are modulated by environmental conditions and during fungal thermo-dimorphism. Thus, this work brings new possibilities for studying the role of aspartyl proteases in the host–pathogen relationship and P. brasiliensis biology.

Background: Saliva is a non-invasive source of biomarkers useful in the study of different pathophysiological conditions. The qualitative and quantitative study of saliva, as well as the assessment of oral health, can be particularly useful for a better understanding of obesity due to its importance in the food oral perception and ingestion. Objectives:To evaluate the effect of treatment of morbid obesity (dietary counselling versus gastroplasty) on salivary characteristics, oral sensory perception and dental health in a controlled study.Methods: Seventy-three adults (60 females; 19-59 years) with morbid obesity were divided in: Control group (CG; n = 34) followed-up during a 6-months dietary programme, and Gastroplasty group (GG; n = 39) evaluated immediately before, 3 and 6 months after gastroplasty. Dietary habits, Oral Health Impact Profile and xerostomia complaints were investigated by interview. The clinical examination included anthropometric and caries experience evaluation. Salivary flow rate, buffering capacity, total protein and alpha-amylase levels, and sensitivity for the four basic tastes were assessed. Two-way mixed model and sign test were applied.Results: Physical and clinical aspects did not differ between groups in the beginning of the study, and GG showed a rapid weight loss after surgery (p < .001). An improvement in most of the dietary aspects was observed, especially in the GG. A worsening in the dental health status was observed over time in both groups, with an increase in the number of filled and decayed teeth. CG showed a better oral health-related quality of life, while xerostomia complains increased in GG after gastroplasty. Salivary flow rate remained stable in both groups, but a decrease in buffering capacity, total protein and alpha-amylase activity was observed in GG after 6-months; taste sensitivity increased from baseline to 6-months in GG (p < .05). Conclusion:After 6-months of follow-up, patients undergoing gastroplasty presented an improvement in dietary habits and taste sensitivity. However, changes in saliva composition and a worsening in dental health status and xerostomia complaints were also observed.