Biology subjects

Araujo, M.

Publications and source records attributed to Araujo, M..

12 recordsLinked to original sources

bioRxiv2026

Chronic warming, not heatwaves, predicts tropical fish colonization in the Mediterranean

The opening of the Suez Canal abruptly reconnected the Red Sea and the Mediterranean Sea, collapsing a geological barrier that had separated their biotas for millions of years. This exchange offers a natural experiment to determine whether tropical species' spread at their cold-edge range is driven by acute thermal shocks (marine heatwaves) or by progressive easing of physiological constraints under sustained warming. We analyzed 1,059 first-arrival time series for 75 non-indigenous fish species across the Mediterranean, explicitly accounting for progressive salinification, oceanographic connectivity, and historical canal enlargement. Our models demonstrate that colonization dynamics are overwhelmingly dominated by ecological momentum-the time-dependent geographic spread of populations-and facilitated by chronic background warming. Marine heatwaves explain negligible variance and show no detectable effect on colonization success. Instead, warming operates as a stage-dependent continuous climatic facilitator, accelerating post-establishment expansion, rather than triggering introductions. Thus, this shift toward warm-adapted communities is governed by chronic warming, with the Suez Canal triggering the reorganization of Mediterranean biogeography.

ecology↗

bioRxiv2026

Inhibition of V-ATPase function drives apoptosis via GCN1/GCN2 kinase signaling

Natural products are a rich source of bioactive molecules that have served both as templates for drug discovery and as tools to uncover fundamental biological processes. While characterizing the pro-apoptotic activity of the cyanobacterial metabolite Nostatin A, we identified vacuolar-type H-ATPase (V-ATPase) as its molecular target and uncovered an unexpected signalling response preceding cell death initiation. V-ATPase inhibition rapidly activates the integrated stress response (ISR) through engagement of the GCN1/GCN2 kinase module, indicative of ribosomal collisions and translational shutdown. This response is conserved across established V-ATPase inhibitors, including bafilomycin A1, but not with compounds disrupting lysosomal function by other means. Mechanistically, V-ATPase inhibition depletes the pro-survival protein MCL-1 resulting in BAX/BAK-dependent mitochondrial apoptosis. Loss of MCL-1 creates a vulnerability that renders cells dependent on co-expressed BCL-2 family proteins, enabling potent synergy with the BH3 mimetics ABT-737 or venetoclax. Taken together, our results reveal a therapeutically exploitable vulnerability in V-ATPase-reliant or MCL-1 dependent cancers.

cell biology↗

bioRxiv2026

In Vitro Activity of a Novel Metal-Based Antimicrobial against Multidrug-Resistant Klebsiella pneumoniae

Multidrug-resistant (MDR) Klebsiella pneumoniae, classified by the World Health Organization (WHO) as a critical priority pathogen, represents a global health thereat requiring novel antimicrobials urgently. Here we evaluated the in vitro antimicrobial activity of a novel iridium-based compound (OMKP-3), against MDR K. pneumoniae. OMKP-3 exhibited robust antimicrobial activity in M9 minimal media (MIC=6.25{micro}g/mL) and rapid bactericidal effect (MBC=12.5{micro}g/mL) against the tested MDR K. pneumoniae strains. OMKP-3 showed antibiofilm ability and was active against multiple MDR Gram-negative pathogens, including Escherichia coli, Enterobacter cloacae, Pseudomonas aeruginosa and Serratia marcescens (MIC range:6.25-25{micro}g/mL). Importantly, OMKP-3 showed no cytotoxicity against mammalian cells after 24 hours of exposure. When combined with polymyxin B, OMKP-3 acted as an adjuvant, enhancing polymyxin B activity (FIC[≤]0.5). OMKP-3 was less prone to induce high-level resistance in MDR K. pneumoniae compared to ciprofloxacin, and supressed the growth of resistant bacteria at a low and non-cytotoxic concentration (4xMIC). K. pneumoniae strains harboring truncated Ompk35/36 porin genes exhibited higher OMKP-3 MICs, indicating that these porins may serve as an important entry pathway. Spectrometry analysis revealed that OMKP-3 was able to accumulate intracellularly (1.57{micro}g/mL), with minimal Resistance-Nodulation-Division (RND) efflux pump extrusion involvement. Furthermore, analysis of the resistant mutant, harboring a mutation in the outer membrane protein DegS, together with fluorescence microscopy, suggests that OMKP-3 induces membrane-associated damage. No cross-resistance between OMKP-3 and commonly used antibiotics was observed. Collectively, these findings identify OMKP-3 as a promising novel antimicrobial agent against MDR K. pneumoniae, likely acting through an unexplored bacterial target. ImportanceMultidrug-resistant (MDR) Klebsiella pneumoniae is a critical global health threat and is among the leading causes of hospital0hyphenorendash;associated mortality, largely due to the scarcity of effective therapeutic options. Alarmingly, the current antimicrobial pipeline fails to address this issue, relying largely on derivatives of existing scaffolds that offer only short-term clinical benefit due to rapid resistance emergence. Developing antibiotics against Gram-negative pathogens is particularly challenging because of their highly impermeable outer membrane and efficient efflux systems, limiting intracellular drug accumulation. Metal-based antimicrobials emerge as a promising alternative. Our findings showed that OMKP-3, an iridium complex, exhibits potent bactericidal activity against MDR K. pneumoniae without selecting for high-level resistance, suggesting the potential for sustained therapeutic efficacy. Additionally, it demonstrated to accumulate intracellularly with minimal efflux involvement. Together, these features position OMKP-3 as a valuable and underexplored novel antimicrobial strategy for addressing the escalating threat of MDR K. pneumoniae infections.

microbiology↗

bioRxiv2026

Microtubules sustain the fidelity of cellularization in a coenocytic relative of animals

Cellularization is the coordinated division of a multinucleate cytoplasm into many cells.1-3 Multinucleation is a common life cycle strategy observed across eukaryotic lineages, including in microbial eukaryotes, fungi, plants and animals, and is associated with the ability to transition to a unicellular state through cellularization.4 In the best-studied model for this process, Drosophila melanogaster, cellularization requires the coordinated action of actin and microtubule (MT) networks to bring about the synchronous invagination of plasma membrane furrows, but the extent of conservation of these mechanisms across eukaryotes remains unknown.1,5,6 Here we investigate cellularization in the ichthyosporean Sphaeroforma arctica, a close relative of animals with a multinucleate life cycle stage.7-9 Using live cell imaging, ultrastructure expansion microscopy (U-ExM) and volume electron microscopy, we define the membrane, MT and actin dynamics that accompany cellularization in S. arctica. Using pharmacological inhibitors and centrifugation, we show that MTs, in addition to positioning nuclei, play a role in guiding nascent furrows to sustain equi-partitioning of nuclei and cytoplasm between daughter cells. Our findings indicate that cellularization is regulated through crosstalk between actin and MT networks, exhibiting mechanistic parallels with canonical cytokinesis, and establish S. arctica as a valuable model for investigating general principles of cellularization.

cell biology↗

bioRxiv2025

Matrix stress-relaxation and stiffness modulate oligodendrocyte differentiation

Impaired remyelination capacity, observed not only in demyelinating diseases of the central nervous system (CNS) but also in the aging brain, features a critical challenge in neural repair. Dysfunctional oligodendrocytes (OLs) are not able to efficiently restore myelin sheaths leading to increased axonal susceptibility to degeneration. Inhibitory cues to OL myelination have been described but strategies promoting remyelination keep failing. Recently acknowledged as key regulators of cellular fate and behavior, physical properties are emerging as novel potential targets in remyelination. Yet, the full extent of this impact is unknown. So far, the viscoelastic properties of the brain have been overlooked, with studies assuming that it only possesses an elastic behavior. Here, we engineered mechanically tunable 3D alginate hydrogels for culturing OLs. While being structurally biologically relevant, our matrices can be modelled in terms of elastic and viscoelastic properties. For the first time, we proved that, in addition to elasticity, viscoelasticity highly impacts the behavior of OLs. High stress-relaxation and shear moduli hydrogels lead to impaired differentiation, branching ability and metabolic activity of OLs, without visible effects on cellular viability. We showed that tuning alginate stress-relaxation properties while maintaining the stiffness triggers activation of mechanotransduction genes. Alterations were seen in genes involved in the focal adhesion kinase pathway as well as in the transcriptional factors Yap 1 and Taz and at the level of nuclear mechanotransduction (Hdac1). Understanding how microenvironmental cues support OL viability and myelination might lead to the design of improved therapies promoting remyelination. Our tunable hydrogels are not only relevant to study OL mechanobiology but can also function as a relevant model to test novel therapeutic interventions in remyelination context.

neuroscience↗

bioRxiv2025

Anti-malarial contact dependent blocking of transmission of Plasmodium vivax by Anopheles darlingi mosquito vector

Malaria, caused by protozoa of the genus Plasmodium and transmitted to humans through the bite of mosquitoes of the genus Anopheles, remains a public health problem. Long-Lasting Insecticide -treated bed Nets (LLINS) and Indoor Residual Spraying (IRS) represent the main vector control measures for malaria prevention. However, to address the concerns of mosquito resistance to pyrethroids, other malaria control strategies are being explored for effectively blocking malaria transmission by eliminating or reducing the parasite in the vector. This study evaluated the use of antimalarials through tarsal contact of female Anopheles darlingi infected with Plasmodium vivax via a Direct Membrane Feeding Assay (DMFA). Female An. darlingi were exposed tarsally using Petri dishes impregnated with antimalarials at 1 mmol/m2 for exposure times of 6 or 60 minutes. Among the antimalarials evaluated were Atovaquone (ATQ), Tafenoquine (TQ), Chloroquine (CQ), Mefloquine (MQ), Primaquine (PQ), and the compound Nanchangmycin (NCG). Atovaquone was the only antimalarial evaluated before and after DMFA at exposure times of 60 min and 6 min. The results demonstrate complete elimination of P. vivax in female An. darlingi exposed to ATQ by tarsal contact 60 min before infection. ATQ was also effective 6 min before or after infection, reducing infection prevalence. In addition, MQ also significantly reduced infection intensity, but there was no difference in infection prevalence. No significant differences were observed for the other antimalarials. Author SummaryMalaria caused by Plasmodium vivax is the most prevalent in the Amazon region, with Anopheles darlingi as its main vector. Mosquito resistance to pyrethroid insecticides, already described in African countries, also raises an alarm for areas endemic for vivax malaria. Given this scenario, strategies that involve blocking parasite transmission have proven effective. Our study involved the transmission-blocking potential of antimalarials administered via tarsal contact to An. darlingi infected with P. vivax. Tarsal exposure involves the direct contact of the mosquitoes tarsi with surfaces impregnated with antimalarials. We speculate that in a real-world setting, this approach could be translated by treating surfaces like bed nets, eaves, or resting sites with the compounds, exploiting the natural resting and host-seeking behaviors of mosquitoes that bring their tarsi into contact with these treated substrates. If the drugs/compounds penetrate the cuticle, they could impact the parasites biological cycle within the vector. Our results confirmed this potential, Atovaquone was able to eliminate or reduce P. vivax from the midguts of An. darlingi at different exposure times, demonstrating successful uptake through the tarsi. Mefloquine was also reduced parasite intensity via tarsal contact. These findings reinforce the potential of this approach as a complementary tool in malaria control.

zoology↗

bioRxiv2024

Cross-species transmission of human hepatitis B virus to wild Neotropical primates

Hepatitis B virus (HBV) infects approximately one-third of the worlds human population and kills over one million people each year. HBV is also prevalent in Old World apes but not in New World primates. Human-to-primate transmission of HBV was suspected in zoo-captive monkeys and Mauritius macaques, but empirical data are scarce. Here, we collected blood and liver samples from 88 monkeys of 27 species in two areas of the Amazon, one with pristine forest and the other highly occupied and deforested by humans. A total of 17 (34.7%) out of 49 specimens from the human-occupied region tested positive for HBV. At this site, there was a positive relationship between human population density in the sampling location and the likelihood of primates being infected by HBV. Conversely, all 39 samples from the pristine forest tested negative for HBV. By sequencing a portion of the HBV S gene in five positive samples, each from a distinct primate genus, we found that four samples were closely related to the globally widespread human HBV-A strain, but not to the Americas-native HBV-F strain. The fifth sample aligned with the human HBV-D type, prevalent in the region where these samples were obtained. To our knowledge, this study represents the first reported cases of HBV in multiple wild New World primate species anywhere in the world. Our results suggest that primates were infected by strains brought into this part of Brazil by human immigrants, where HBV transmission may have been facilitated by the close contact between humans and monkeys due to high human occupation. This shows that the impact of human immigration, occupation and population growth in the Amazon extends beyond habitat loss; it also facilitates cross-species infections, potentially leading to the emergence of new, virulent viral strains that threaten both Amazonian biodiversity and human health. Author SummaryJean P. Boubli: Professor in Primate Ecology and Evolution, School of Science, Engineering and the Environment, University of Salford, Uk Hani R. El Bizri: PhD in Wildlife Conservation with a focus on Amazonian sustainable development. Analyst of Center for International Forestry Research (CIFOR), Bogor, Indonesia Luan F. Botelho-Souza: Masters and doctorate in experimental biology at the Universidade Federal de Rondonia/Brazil, Chrysoula Gubili: Researcher at the Fisheries Research Institute Nea Peramos, Kavala, Greece, specializing in population ecology and conservation genetics. Stephen J. Martin: Professor in Social Insects, School of Science, Engineering and the Environment, University of Salford, Uk Maisa da S. Araujo: Masters and doctorate in experimental biology, at the Universidade Federal de Rondonia/Brazil, Mariluce R. Messias: Professor of Zoology and curator of the Mammalogy Museum at the Universidade Federal de Rondonia/Brazil. Alcione de O. dos Santos: Masters and doctorate in experimental biology at the Universidade Federal de Rondonia/Brazil. Luiz S. Ozaki: Masters degree from Universidade de Brasilia and PhD in Physiological Sciences, Molecular Biology in Fukuoka, Kyushu, Japan. Andre V.C. Pereira: Bachelor in Biology the Universidade Federal de Rondonia/Brazil. Tony H. Katsuragawa: Masters and doctorate in experimental biology, at the Universidade Federal de Rondonia/Brazil. Ana Maisa Passos-Silva: Masters degree in experimental biology from the Federal University of Rondonia/Brazil. Luiz H. S. Gil: Masters in experimental biology, at the Universidade Federal de Rondonia/Brazil. Izeni P. Farias: Professor of Genetics, Universidade Federal do Amazonas, Brazil Juan M.V. Salcedo: Master in Tropical Medicine from the University of Brasilia/Brazil and PhD in Sciences from the University of Sao Paulo/Brazil. Tommy C. Burch: Masters in Biological Sciences and PhD candidate from the University of Salford, UK. Deusilene Vieira: Master in Tropical Medicine from the University of Brasilia/Brazil and PhD in Sciences from the University of Sao Paulo/Brazil.

pathology↗

bioRxiv2024

Charting the landscape of cytoskeletal diversity in microbial eukaryotes

Microbial eukaryotes are small and often resistant to standard labelling and imaging techniques, and therefore remain understudied - despite their critical ecological importance - with the exception of a few established models. Here, we use Ultrastructure Expansion Microscopy (U-ExM) to carry out high-resolution volumetric imaging of over 200 cultured planktonic eukaryotes across major lineages. By combining U-ExM with pan- and specific immuno-labelling, we reveal novel microtubule and centrin-containing elements and assign molecular identities to enigmatic cytoskeletal structures observed previously only by electron microscopy. Our investigation represents the first systematic survey of the extensive cytoskeletal diversity on display across the eukaryotic tree, including the major species groups of dinoflagellates, haptophytes, ciliates, euglenids, cryptomonads, and green algae. Our U-ExM approach extends to mixed environmental samples, paving the way for environmental cell biology at ultrastructural resolution and unprecedented scale, a crucial step towards understanding and protecting complex ecosystems in the face of biodiversity loss.

cell biology↗

bioRxiv2024

Coastal oceanographic connectivity estimates at the global scale

MotivationOceanographic connectivity driven by ocean currents is critical in determining the distribution of marine biodiversity. It mediates the genetic and individual exchange between populations, from structuring dispersal barriers that promote long-term isolation to enabling long-distance dispersal that underpins species expansion and resilience against climate change. Despite its significance, comprehensive estimates of oceanographic connectivity on a global scale remain unavailable, while traditional approaches, often simplistic, fail to capture the complexity of oceanographic factors contributing to population connectivity. This gap hinders a deeper understating of species dispersal ecology, survival, and evolution, ultimately precluding the development of effective conservation strategies aimed at preserving marine biodiversity. To address this challenge, we present a comprehensive dataset of connectivity estimates along the worlds coastlines, known for their rich marine biodiversity. These estimates are derived from a biophysical modelling framework that combines high-resolution ocean current data with graph theory to predict multi-generational stepping-stone connectivity. Alongside, we provide coastalNet, an R package designed to streamline access, analysis, and visualization of connectivity estimates. This tool enhances the utility and application of the data, adhering to the FAIR principles of Findability, Accessibility, Interoperability, and Reusability. The dataset and package set a new benchmark for research in oceanographic connectivity, allowing a better exploration of the complex dynamics of coastal marine ecosystems. Main types of variables containedPairwise connectivity estimates (probability and time) between coastal sites. Spatial location and grainGlobal, equal-area hexagons with 8.45 km edge length. Time period and grainDaily, from 2000 to 2020. Major taxa and level of measurementCoastal marine biodiversity. Software formatA package of functions developed for R software.

ecology↗

bioRxiv2022

Machine Learning Electroencephalography Biomarkers Predictive of Epworth Sleepiness Scale

Excessive daytime sleepiness (EDS) causes difficulty in concentrating and continuous fatigue during the day. In a clinical setting, the assessment and diagnosis of EDS relies mostly on subjective questionnaires and verbal reports, which compromises the effectiveness of available therapies. In this study, we used a computational pipeline for the automated, rapid, high-throughput and objective analysis of retrospective encephalography (EEG) data to develop objective, surrogate biomarkers for EDS, thereby defining the quantitative EEG changes in individuals with High Epworth Sleepiness Scale (ESS) (n=31), compared to a group of individuals with Low ESS (n=41) at Cleveland Clinic. Signal processing of EEG showed significantly different EEG features in the Low ESS group compared to High ESS, including power enhancement in the alpha and beta bands, and attenuation in the delta and theta bands. Moreover, machine learning algorithms trained on the binary classification of High vs Low ESS reached >80% accuracy. These results demonstrate that EEG data contain information in the form of rhythmic activity that could be leveraged for the quantitative assessment of EDS using machine learning.

neuroscience↗

bioRxiv2022

Endoplasmic Reticulum membranes are continuously required to maintain mitotic spindle size and forces

Membrane organelle function, localization, and proper partitioning upon cell division depend on interactions with the cytoskeleton. Whether, reciprocally, membrane organelles also impact on the function of cytoskeletal elements remains less clear. Here, we show that acute disruption of the Endoplasmic Reticulum (ER) around spindle poles affects mitotic spindle size and function in Drosophila syncytial embryos. Acute ER disruption was achieved through the inhibition of ER membrane fusion by the dominant-negative cytoplasmic domain of Atlastin. We reveal that when the ER is disrupted specifically at metaphase, mitotic spindles become smaller, despite no significant changes in microtubule dynamics. These smaller spindles are still able to mediate sister chromatid separation, yet with decreased velocity. Furthermore, by inducing mitotic exit, we found that nuclear separation and distribution are affected upon ER disruption. Our results suggest that ER integrity around spindle poles is crucial for the maintenance of mitotic spindle shape and pulling forces. Additionally, ER integrity also ensures nuclear spacing during syncytial divisions.

cell biology↗

bioRxiv2020

Metagenome-assembled genomes from Monte Cristo Cave (Diamantina, Brazil) reveal prokaryotic lineages as functional models for life on Mars

Although several studies have explored microbial communities in different terrestrial subsurface ecosystems, little is known about the diversity of their metabolic processes and survival strategies. The advance of bioinformatic tools is allowing the description of novel and not-yet cultivated microbial lineages in different ecosystems, due to the genome reconstruction approach from metagenomic data. The recovery of genomes has the potential of revealing novel lifestyles, metabolic processes and ecological roles of microorganisms, mainly in ecosystems that are largely unknown, and in which cultivation could be not viable. In this study, through shotgun metagenomic data, it was possible to reconstruct several genomes of cultivated and not-yet cultivated prokaryotic lineages from a quartzite cave, located in Minas Gerais state, Brazil, which showed to possess a high diversity of genes involved with different biogeochemical cycles, including reductive and oxidative pathways related to carbon, sulfur, nitrogen and iron. Tree genomes were selected, assigned as Truepera sp., Ca. Methylomirabilis sp. and Ca. Koribacter sp. based on their lifestyles (radiation resistance, anaerobic methane oxidation and potential iron oxidation) for pangenomic analysis, which exhibited genes involved with different DNA repair strategies, starvation and stress response. Since these groups have few reference genomes deposited in databases, our study adds important genomic information about these lineages. The combination of techniques applied in this study allowed us to unveil the potential relationships between microbial genomes and their ecological processes with the cave mineralogy, as well as to discuss their implications for the search for extant lifeforms outside our planet, in silica- and iron-rich environments, especially on Mars.

microbiology↗