Biology subjects

Fontes, W.

Publications and source records attributed to Fontes, W..

4 recordsLinked to original sources

bioRxiv2026

Bacterial Extracellular Vesicles from Chromobacterium subtsugae and Bacillus thuringiensis as Cell-Free Bioinsecticidal Nanocarriers Against the Soybean Pest Euschistus heros

Bacterial extracellular vesicles (bEVs) are membrane-enclosed nanoparticles that transport bioactive cargo and mediate interactions between bacteria and their environment. Although bEVs are increasingly recognized as natural delivery systems, their potential application in plant pest biocontrol remains poorly explored. Here, we provide proof-of-concept evidence that isolated bEVs from two entomopathogenic bacteria, Chromobacterium subtsugae and Bacillus thuringiensis var. kurstaki, exert insecticidal activity against the soybean pest Euschistus heros. Isolated bEVs were characterized by tunable resistive pulse sensing, nano-flow cytometry, transmission electron microscopy, SDS-PAGE, MALDI-TOF mass spectrometry, and label-free quantitative proteomics. C. subtsugae bEVs displayed a proteome clearly remodeled relative to the soluble protein fraction, with enrichment of outer- membrane, secretion-associated, proteolytic, and membrane-active proteins. MALDI-TOF analysis detected a violacein-associated ion selectively in the C. subtsugae bEV fraction, supporting vesicular association of this hydrophobic bioactive metabolite. In survival assays, C. subtsugae bEVs strongly reduced E. heros nymph survival (HR = 4.0, p < 0.0001), whereas the corresponding soluble protein fraction was inactive (HR = 1.2, p = 0.50). In contrast, B. thuringiensis bEVs and soluble protein fractions produced similar moderate activity (both HR = 2.1), consistent with their largely overlapping proteomic profiles. Cry1Ab was detected mainly in the B. thuringiensis soluble fraction rather than selectively enriched in bEVs. Together, these findings support a multi-component cargo model in which C. subtsugae bEVs combine vesicle-associated violacein with enriched protein cargo, establishing bacterial EVs as promising natural nanocarriers for next-generation, cell-free bioinsecticides against Cry-resistant hemipteran pests such as E. heros.

microbiology↗

bioRxiv2025

Rapid CE-MS with Real-Time Eco-AI Resolves Proteomic Heterogeneity Among Single Human Neutrophils

Single-cell proteomics by mass spectrometry is advancing rapidly, yet throughput and sensitivity remain limiting--particularly for small, protein-poor cell types such as neutrophils. As the most abundant circulating leukocytes in humans, neutrophils are central to immune defense and inflammation, but their proteomes comprehensive single-cell level characterization has only concurrently been reported1 and remains limited. Here, we introduce a rapid capillary electrophoresis-mass spectrometry (CE-MS) platform, which integrates electrophoresis-correlative real-time data acquisition with sub-7-minute separations and artificial intelligence (AI)-based data processing software to achieve deep, high-throughput profiling. Using single-cell-equivalent HeLa digests, the Rapid Eco-AI platform identified [~]1,350 proteins from 300 pg and [~]835 proteins from 75 pg of input-- approaching the complexity of a mammalian cell proteome. Applied to freshly isolated human neutrophils, the workflow identified 151 proteins from [~]2 pg of material, [~]3% of the total cell proteome. Analysis of 13 individual cells revealed marked functional heterogeneity across pathways of degranulation, neutrophil extracellular trap (NET) formation, chemotaxis, and innate immunity, with hierarchical clustering resolving at least four distinct proteomic subtypes. These results establish Rapid Eco-AI as a sensitive, scalable, and broadly applicable CE-MS approach for immune-cell phenotyping at single-cell and subcellular resolution, facilitating new research opportunities in systems immunology and clinical proteomics.

developmental biology↗

bioRxiv2018

NetWheels: A web application to create high quality peptide helical wheel and net projections.

Helices are one of the most common secondary structures found in peptides and proteins. The wheel and net projections have been proposed to represent in two dimensions the tridimensional helical structures and facilitate the observation of their properties, especially in terms of residues polarity and intramolecular bonding. Nevertheless, there are few software options to create these projections. We have developed a web-based application that has several futures to create, customize and export these projections and is freely available at http://lbqp.unb.br/NetWheels.

bioinformatics↗

bioRxiv2018

Label free quantitative proteomics of Qualea grandiflora Mart. (Vochysiaceae) roots indicates an aluminium requirement for growth and development.

Aluminium in acid soils is a hindrance to crop growth. Nonetheless, Brazilian Cerrado possesses many species such as Qualea grandiflora, which are adapted to acid soils with large amounts of Al and accumulate this metal in its tissues and organs. Nonetheless, the mechanisms involved in these processes are poorly understood, mainly at molecular level. Thus, a root proteomic analysis was accomplished to identify Al-responsive proteins in Q. grandiflora plants. Concomitantly, a root growth analysis of plants grown with and without Al supplementation was conducted to determine the effects of Al on the whole plant. Subsequently, proteins from both treatments were identified and quantified by LC-MS/MS in a label-free fashion. From the 2,520 identified proteins, 410 were differentially abundant between the two treatments, which were associated with carbohydrate metabolism, redox activity, stress response and catabolism of organic compounds. Furthermore, Al was crucial for the growth and development of Q. grandiflora. In fact, this species may have an Al-dependent metabolism. Moreover, it was possible to correlate plant growth to Al-upregulated proteins that were directly involved in cell wall synthesis, oxidative phosphorylation, genetic information processing, and amino acid metabolism. Additionally, this work provides an extensive dataset of Al-regulated protein in Q. grandiflora, which will be crucial to understanding the functions of Al in this species.

plant biology↗