Biology subjects

Alves, C.

Publications and source records attributed to Alves, C..

6 recordsLinked to original sources

bioRxiv2026

Discovery of Novel Ligands for Cryptococcus neoformans

Fungal pathogens are an escalating global public health concern, particularly in the context of invasive and opportunistic infections. Cryptococcosis, primarily caused by Cryptococcus neoformans var. grubii, can manifest as acute, subacute, or chronic disease, affecting multiple organs and frequently leading to life-threatening meningitis in immunocompromised individuals. Given the limited antifungal therapeutic strategies and the emergence of resistance and toxicity-related constraints, the development of novel anti-cryptococcal agents remains an urgent priority. In this study, a library of innovative hybrids (5a-f) based on the 3-hydroxypyridin-4(1H)-one scaffold was developed. Their antimicrobial activity was evaluated towards a panel of clinically relevant Gram-positive (methicillin-resistant Staphylococcus aureus - MRSA) and Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii), as well as fungal species Candida albicans and Cryptococcus neoformans var. grubbi. Cytotoxicity was assessed in HEK293 and HepG2 cell lines, and haemolytic profile was determined to evaluate safety. In addition, iron-chelating capacity and lipophilic properties were also investigated. All compounds formed stable complexes with iron(III) and were non-toxic at concentrations up to 25 M. Lipophilicity studies showed that compounds in series 1 (5a-c) exhibited lower lipophilicity than those in Series 2 (5d-f), mainly due to the regioisomeric position of the hydroxyl group on the 2-methyl-4-pyridone scaffold; specifically, the C3-substitution pattern in Series 2 that enhances the hydrophobic character compared to the C5-substitution in Series 1. Fluorination further increased lipophilicity in both series. Notably, compounds 5c-5f emerged as potent, selective, and non-toxic antifungal agents against Cryptococcus neoformans var. grubii (MIC < 16 {micro}g/mL; CC50 > 32 {micro}g/mL; HC10 > 32 {micro}g/mL). Their distinct structural features appear to play a key role in antifungal selectivity, supporting the potential of these 3-hydroxypyridin-4(1H)-one-based hybrids as promising approach for the development of novel therapeutics for cryptococcal meningitis.

pharmacology and toxicology↗

bioRxiv2025

Network Rerouting Under Ayahuasca: Temporally and Hemisphere-Resolved EEG Connectomics

Ayahuasca profoundly alters conscious experience, yet robust, time-resolved EEG markers of its network-level effects remain limited. We combined machine learning with complex-network analysis to quantify how functional connectivity reorganizes across time and hemispheres in resting-state EEG from a randomized, double-blind, placebo-controlled trial including three 5-min sessions: pre-dose (T1), 2 h post-dose (T2), and 4 h post-dose (T3). The cohort consisted of naive ayahuasca users, a population known to exhibit attenuated or more stable acute responses, making the detection of network-level changes particularly challenging. Connectivity was estimated using multiple metrics and sliding windows (10-120 s), and network features were computed and averaged to ensure statistical validity. A representation-selection step identified Spearman correlation and an intermediate temporal scale as optimal, with classification performance peaking at 60-70 s (independent-test AUC and accuracy = 0.93). Linear mixed models revealed a bilateral decrease in eigenvector centrality (weaker hub influence), increased degree heterogeneity in the right hemisphere, and reduced global efficiency in the left. Edge-level analyses localized these effects: Posterior-left connections weakened acutely (lowest at T2), whereas right temporal-central coupling transiently strengthened (highest at T2). Together, these convergent results support a mechanistic summary: as hub-centric short-cuts weaken, communication is increasingly routed through alternative, more distributed--and less efficient--pathways, with a right-lateralized expression at a later time. Methodologically, the window-optimized, hemisphere-resolved, and edge-validated pipeline extends prior EEG work and highlights temporal scale (approximately 60 s) as a biologically meaningful parameter for detecting psychedelic-induced network reorganization.

neuroscience↗

bioRxiv2025

MAPK Signaling and Angiopoietin-2 Contribute to Endothelial Permeability in Capillary Malformations

Capillary malformations (CM) are slow-flow vascular abnormalities present at birth and predominantly manifest as cutaneous lesions. In the rare neurocutaneous disorder known as Sturge Weber Syndrome (SWS), individuals exhibit CM not only on the skin but also within the leptomeninges of the brain and the choroid of the eye. >90% of CM are caused by a somatic R183Q mutation in GNAQ, the gene encoding Gq - a heterotrimeric G-protein subunit. The somatic GNAQ mutation is notably enriched in endothelial cells (ECs) isolated from CM-affected regions. Here we show blood vessels in cutaneous and leptomeningeal SWS lesions exhibit extravascular fibrin indicating a compromised endothelial barrier. Longitudinal MRI of the brain in one SWS patient further suggests vascular permeability. To explore this pathological phenotype, we employed the trans-endothelial electrical resistance (TEER) assay to measure permeability of the EC-EC barrier in vitro. Human EC CRISPR edited to create a GNAQ R183Q allele (EC-R183Q) exhibited a reduced barrier compared to mock edited EC (EC-WT). We sought to identify signaling molecules needed for EC barrier formation. Knockdown of angiopoietin-2 (ANGPT2), known to be significantly increased in EC-R183Q and in CM, partially yet significantly restored the barrier, while an anti-ANGPT2 function blocking antibody did not. We next tested the MEK1,2 inhibitor (Trametinib) because MAPK signaling is increased by GNAQ mutation. MEK1,2 inhibitors partially restored the EC barrier, implicating involvement of MAPK/ERK signaling. The combination of ANGPT2 knockdown and Trametinib significantly restored the EC barrier to near EC-WT levels. The additive impacts of ANGPT knockdown and MEK1,2 inhibition indicate the two operate in separate pathways. In summary, we discovered that GNAQ p.R183Q ECs exhibit compromised endothelial barrier formation, reflecting the compromised EC barrier in CM lesions, and that ANGPT2 knockdown combined with Trametinib effectively restores the EC-EC barrier. NONSTANDARD ABBREVIATIONS AND ACRONYMS O_TBL View this table: org.highwire.dtl.DTLVardef@e1081eorg.highwire.dtl.DTLVardef@1dc05b7org.highwire.dtl.DTLVardef@1fb6ac0org.highwire.dtl.DTLVardef@11d8f59org.highwire.dtl.DTLVardef@1ae5406_HPS_FORMAT_FIGEXP M_TBL C_TBL NOVELTY AND SIGNIFICANCEO_ST_ABSWhat is known?C_ST_ABSO_LIThe mutant Gq-R183Q in endothelial cells activates phospholipase {beta}3, contributing to increased angiopoietin-2, a pro-angiogenic, proinflammatory molecule that contributes to vascular permeability. C_LIO_LIEndothelial Gq-R183Q is sufficient to drive formation of enlarged blood vessels akin to what is observed in CM. ANGPT2 shRNA knockdown prevented the enlarged vessel phenotype in a xenograft model. C_LIO_LIAn EC-specific GNAQ p.R183Q mouse model showed permeability in brain vessels, detected by perfusion of Evans Blue dye, indicating reduced vascular integrity. C_LI What New Information Does This Article Contribute?O_LIReduced vascular integrity in CM is confirmed by Martius Scarlet Blue staining and longitudinal MRI imaging of SWS brain. C_LIO_LIGNAQ p.R183Q EC form a weaker endothelial barrier in vitro compared to control ECs. The weakened endothelial barrier in the mutant ECscan be rescued by Gq inhibitor, YM254890, confirming the compromised barrier is a consequence of the mutant Gq. C_LIO_LITitration experiments modeling the mosaic nature of the GNAQ p.R183Q in CMshow that 5- 10% GNAQ p.R183Q EC in the monolayer is sufficient to reduce endothelial barrier formation. C_LIO_LIKnockdown of ANGPT2 or MEK1,2 inhibition partially restored the endothelial barrier in GNAQ p.R183Q EC. C_LIO_LICombining knockdown of ANGPT2 and addition of a MEK inhibitor, Trametinib, restored the endothelial barrier to near what is seen in wild type ECs. C_LI What is the translational message?Sturge Weber Syndrome (SWS) is a neurocutaneous disorder that involves atypical blood vessel overgrowth in the skin, brain and eye. It is associated with facial CM (aka port wine birthmark), leptomeningeal CM in the brain visible with MRI, and glaucoma. Theneurological sequalae involve seizures, cerebral atrophies and calcification, and intellectual disorders. Currently there are no molecularly targeted therapies for non-syndromic CM or SWS. Our study shows the involvement of MAPK pathway and the proinflammatory molecule ANGPT2 in endothelial permeability and suggests a path to target GNAQ p.R183Q driven CM.

pathology↗

bioRxiv2024

Zebrafish Avatar-test predicts patient's tumor response to chemotherapy in breast cancer: a co-clinical study towards personalized medicine

Chemotherapy remains the mainstay in most high-risk breast cancer (BC) settings, with several equivalent options of treatment. However, the efficacy of each treatment varies between patients and there is currently no test to determine which option will be the most effective for each individual patient. Here, we developed a fast in-vivo test for BC therapy screening: the zebrafish patient derived xenograft model (zAvatars), where in-vivo results can be obtained in just 10 days. To determine the predictive value of the BC zAvatars we performed a clinical study, where zAvatars were treated with the same therapy as the donor-patient and their response to therapy was compared. Our data shows a 100% correlation between patients clinical response to treatment and its matching zAvatar. Altogether, our results suggest that the zAvatar model constitutes a promising in-vivo assay to optimize cancer treatments in truly personalized manner.

cancer biology↗

bioRxiv2024

An inappropriate decline in ribosome levels drives a diverse set of neurodevelopmental disorders

Many neurodevelopmental defects are linked to perturbations in genes involved in housekeeping functions, such as those encoding ribosome biogenesis factors. However, how reductions in ribosome biogenesis can result in tissue and developmental specific defects remains a mystery. Here we describe new allelic variants in the ribosome biogenesis factor AIRIM primarily associated with neurodevelopmental disorders. Using human cerebral organoids in combination with proteomic analysis, single-cell transcriptome analysis across multiple developmental stages, and single organoid translatome analysis, we identify a previously unappreciated mechanism linking changes in ribosome levels and the timing of cell fate specification during early brain development. We find ribosome levels decrease during neuroepithelial differentiation, making differentiating cells particularly vulnerable to perturbations in ribosome biogenesis during this time. Reduced ribosome availability more profoundly impacts the translation of specific transcripts, disrupting both survival and cell fate commitment of transitioning neuroepithelia. Enhancing mTOR activity by both genetic and pharmacologic approaches ameliorates the growth and developmental defects associated with intellectual disability linked variants, identifying potential treatment options for specific brain ribosomopathies. This work reveals the cellular and molecular origins of protein synthesis defect-related disorders of human brain development. HighlightsO_LIAIRIM variants reduce ribosome levels specifically in neural progenitor cells. C_LIO_LIInappropriately low ribosome levels cause a transient delay in radial glia fate commitment. C_LIO_LIReduced ribosome levels impair translation of a selected subset of mRNAs. C_LIO_LIGenetic and pharmacologic activation of mTORC1 suppresses AIRIM-linked phenotypes. C_LI

developmental biology↗

bioRxiv2021

Twenty years of change in benthic communities across the Belizean Barrier Reef

Disease, ocean warming, and pollution have caused catastrophic declines in the cover of living coral on reefs across the Caribbean. Subsequently, reef-building corals have been replaced by invertebrates and macroalgae, leading to changes in ecological functioning. We describe changes in benthic community composition and cover at 15 sites across the Belizean Barrier Reef (BBR) following numerous major disturbances--bleaching, storms, and disease outbreaks--over the 20-year period 1997-2016. We tested the role of potential drivers of change on coral reefs, including local human impacts and ocean temperature. From 1997 to 2016, mean coral cover significantly declined from 26.3% to 10.7%, while macroalgal cover significantly increased from 12.9% to 39.7%. We documented a significant decline over time of the reef-building corals Orbicella spp. and described a major shift in benthic composition between early sampling years (1997-2005) and later years (2009-2016). The covers of hard-coral taxa, including Acropora spp., M. cavernosa, Orbicella spp., and Porites spp., were negatively related to marine heatwave frequency. Only gorgonian cover was related, negatively, to our metric of the magnitude of local impacts (the Human Influence Index). Changes in benthic composition and cover were not associated with local protection or fishing. This result is concordant with studies throughout the Caribbean that have documented living coral decline and shifts in reef-community composition following disturbances, regardless of local fisheries restrictions. Our results suggest that benthic communities along the BBR have experienced disturbances that are beyond the capacity of the current management structure to mitigate. We recommend that managers devote greater resources and capacity to enforce and expand existing marine protected areas and that government, industry, and the public act to reduce global carbon emissions.

ecology↗