Biology subjects

Moreira, J. C. F.

Publications and source records attributed to Moreira, J. C. F..

8 recordsLinked to original sources

bioRxiv2025

Microbial signatures define the ecosystem functions of the pelagic microbiome in a basin-scale, Southwest Atlantic Ocean

BackgroundThe pelagic environment may present a mosaic of biogeographical domains that regional oceanographic processes can influence. Here, a coastal-to-open ocean microbiome investigation was conducted on 64 water samples from the Santos Basin (SB), South Atlantic Ocean. Using metagenomics and machine learning approaches, we assessed the diversity and distribution of pelagic microbes, identified key bacterial and archaeal taxa, and inferred their ecosystem functions. ResultsUnsupervised machine learning revealed a clear spatial and vertical (light availability) distribution pattern across SB, with some indicator taxa previously observed in other marine waters. Supervised learning further revealed that environmental variables, notably phosphate, salinity, and nitrate, which are key markers of local upwelling and the La Plata River plume, are primary drivers of microbial community structure. Furthermore, we recovered 307 metagenome-assembled genomes with 45% of Archaea and 42% of Bacteria possible new taxa. In terms of functionality, the SB dataset revealed a pelagic ecosystem resembling typical marine (e.g., Atlantic Ocean) waters, with photoautotrophs and nitrogen fixers in the photic zone and different autotrophic pathways in the aphotic environment. Surprisingly, the SB dataset revealed genes for CO bio-oxidation and algal dimethylsulfoniopropionate (DMSP) degradation at all depths. Furthermore, we observed potential non- cyanobacterial diazotrophs in dark water. ConclusionsOur results revealed that the SB represents a unique ecosystem with local oceanographic processes shaping the distribution of diverse and uncharacterized microbiomes. Additionally, these findings highlight the importance of mixotrophic microbes in SB biogeochemical cycles. This massive investigation of the SB pelagic microbiome provided knowledge-based data for understanding local ecosystem health, services, and dynamics, which are essential for future sustainable ocean management.

microbiology↗

bioRxiv2025

A Machine Learning Approach Elucidates Spatial Patterns of Environmental Properties Driving Microbial Composition Over Santos Basin, South Atlantic

Microbial communities in marine ecosystems play a pivotal role in global biogeochemical cycles, with particular relevance in ecologically and industrially significant regions such as the Santos Basin (SB), Brazils largest marine sedimentary basin and a hub for oil and gas exploration. Yet, our capacity of predicting the microbial community structure and function remains limited for marine ecosystems. This study investigated the structure of microbial communities across different depths in the SB, using amplicon sequencing data and quantitative cell counts obtained via flow cytometry. Using a hybrid machine learning framework combining Self-Organizing Maps and Random Forest, we identified five distinct microbial assemblages (named microbial associations) in the SB predicted with 86% accuracy. These associations were primarily driven by temperature, water density, salinity, and nutrients such as phosphate and nitrate. Our findings showed a clear stratification of microbial communities across pelagic zones, with temperature as the main factor driving the structure in epipelagic and mesopelagic layers, while salinity and density exerted greater influence in the deeper bathypelagic communities. Temporal and spatial variations, particularly between 2019 and 2021, in regions influenced by the Cabo Frio upwelling and Rio de la Plata plume, further highlighted the impact of regional and local oceanographic processes on community dynamics. The associations from deeper waters harbored more diverse microbial assemblages, and shallow waters, on the other hand, possess higher absolute abundance of microbial cells, suggesting niche specialization across depths. This study underscores the importance of environmental gradients as well as local oceanographic processes in shaping microbial diversity, providing valuable insights into the ecological dynamics of the SB, which are essential for understanding the potential impacts of human activities, such as oil and gas exploration and production, on these critical marine ecosystems.

microbiology↗

bioRxiv2024

LDL exposure disrupts mitochondrial function and dynamics in a hippocampal neuronal cell line

Hypercholesterolemia has been associated with cognitive dysfunction and neurodegenerative disease. Moreover, this metabolic condition disrupts the blood-brain barrier, allowing Low-Density Lipoprotein (LDL) to enter the Central Nervous System. Thus, we investigated the effects of LDL exposure on mitochondrial function in a mouse hippocampal neuronal cell line (HT-22). HT-22 cells were exposed to human LDL (50 and 300 g/mL) for 24 hours. After this, intracellular lipid droplet (LD) content, cell viability, cell death, and mitochondrial parameters were performed. We found that the higher LDL concentration LDL increases LD content compared to control. Both concentrations increased the number of Annexin V-positive cells, indicating apoptosis. Moreover, in mitochondrial parameters, the exposure of LDL on hippocampal neuronal cell line leads to a decrease in mitochondrial complexes I and II in both concentrations tested and a reduction in Mitotracker Red fluorescence and Mitotracker Red and Mitotracker Green ratio in the higher concentration, indicating dysfunction in the mitochondria. The LDL incubation induces mitochondrial superoxide production and a decrease in superoxide dismutase activity in the lower concentration in HT-22 cells. Finally, hippocampal neuronal cell line exposed to LDL exhibit an increase in the expression of genes associated with mitochondrial fusion (OPA1 and Mitofusin 2) in the lower concentration. In conclusion, our findings suggest that LDL exposure induces mitochondrial dysfunction and modulation in mitochondrial dynamics in the hippocampal neuronal cells.

biochemistry↗

bioRxiv2022

Induced pluripotent stem cell-derived astrocytes from patients with schizophrenia exhibit an inflammatory phenotype that affects vascularization

Molecular and functional abnormalities of astrocytes have been implicated in the etiology and pathogenesis of schizophrenia (SCZ). In this study, we examined the proteome, inflammatory responses, and secretome effects on vascularization of human induced pluripotent stem cell (hiPSC)-derived astrocytes from patients with SCZ. Proteomic analysis revealed alterations in proteins related to immune function and vascularization. Reduced expression of the nuclear factor kappa B (NF-{kappa}B) p65 subunit was observed in these astrocytes, with no incremental secretion of cytokines after tumor necrosis factor alpha (TNF-) stimulation. Among inflammatory cytokines, secretion of interleukin (IL)-8 was found particularly elevated in SCZ-patient-derived- astrocyte conditioned medium (ASCZCM). In a chicken chorioallantoic membrane (CAM) assay, ASCZCM reduced the diameter of newly grown vessels, and this effect could be mimicked with exogenous addition of IL-8. Taken together, our results suggest that SCZ astrocytes are immunologically dysfunctional and may consequently affect vascularization through secreted factors.

neuroscience↗

bioRxiv2021

Diversity of free-living prokaryotes on terrestrial and marine Antarctic habitats

Microorganisms in Antarctica are recognized for having crucial roles in ecosystems functioning and biogeochemical cycles. In order to explore the diversity and composition of microbial communities through different terrestrial and marine Antarctic habitats, we analyze 16S rRNA sequence datasets from fumarole and marine sediments, soil, snow and seawater environments. We obtained measures of alpha- and beta-diversities, as well as we have identified the core microbiome and the indicator microbial taxa of a particular habitat. Our results showed a unique microbial community structure according to each habitat, including specific taxa composing each microbiome. Marine sediments harbored the highest microbial diversity among the analyzed habitats. In the fumarole sediments, the core microbiome was composed mainly by thermophiles and hyperthermophilic Archaea, while in the majority of soil samples Archaea was absent. In the seawater samples, the core microbiome was mainly composed by cultured and uncultured orders usually identified on Antarctic pelagic ecosystems. Snow samples exhibited common taxa in comparison to the habitats from the Antarctic Peninsula, which suggests long-distance dispersal processes occurring from the Peninsula to the Continent. This study contributes as a baseline for further efforts on evaluating the microbial responses to environmental conditions and future changes.

microbiology↗

bioRxiv2021

Development of chemosynthetic microbial communities in organic falls deployed in the deep Southwest Atlantic Ocean

The assembly and successional processes of microbial communities inhabiting deep-sea whale and wood falls are highly complex and vastly unknown, as a myriad of factors may affect the development of a chemosynthetic-based ecosystem on these organic islands. The chemoautotrophy supported by organic substrates is the basis of long-lasting ecosystems, considered biodiversity hotspots in the oligotrophic deep sea. Understanding how these microbial communities develop and the factors affecting them could shed light on processes related to the maintenance of biodiversity in this environment. We performed a whale- and wood-fall experiment in the southwest Atlantic on the Brazilian continental margin and investigated biofilm-forming bacterial and archaeal communities colonising these substrates, deployed at 1500 and 3300 m depth. The composition of the prokaryotic communities shared some similarities with previously reported organic falls in the north Pacific and the Mediterranean Sea, mainly regarding sulphur oxidising chemolithotrophic taxa from the phyla Campylobacterota and Proteobacteria. Communities were found to be highly different between the organic substrates, as whale fall associated biofilms presented a higher dominance of sulphur oxidising chemolithotrophs. We also observed a significant difference between the two sites, with the whale associated communities at the 1500 isobath presenting a faster establishment of the chemosynthetic taxa.

microbiology↗

bioRxiv2021

Deep-sea plastisphere: long-term colonization by plastic-associated bacterial and archaeal communities in the Southwest Atlantic Ocean

Marine plastic pollution is a global concern because of continuous release into the oceans over the last several decades. Although recent studies have made efforts to characterize the so-called plastisphere, or microbial community inhabiting plastic substrates, it is not clear whether the plastisphere is defined as a core community or as a random attachment of microbial cells. Likewise, little is known about the influence of the deep-sea environment on the plastisphere. In our experimental study, we evaluated the microbial colonization on polypropylene pellets and two types of plastic bags: regular high density polyethylene (HDPE) and HDPE with the oxo-biodegradable additive BDA. Gravel was used as control. Samples were deployed at three sites at 3,300 m depth in the Southwest Atlantic Ocean and left for microbial colonization for 719 days. For microbial communities analysis, DNA was extracted from the biofilm on plastic and gravel substrates, and then the 16S rRNA was sequenced through the Illumina Miseq platform. Cultivation was performed to isolate strains from the plastic and gravel substrates. Substrate type strongly influenced the microbial composition and structure, while no difference between sites was detected. Although several taxa were shared among plastics, we observed some groups specific for each plastic substrate. These communities comprised taxa previously reported from both epipelagic zones and deep-sea benthic ecosystems. The core microbiome (microbial taxa shared by all plastic substrates) was exclusively composed by low abundance taxa, with some members well-described in the plastisphere and with known plastic-degradation capabilities. Additionally, we obtained bacterial strains that have been previously reported inhabiting plastic substrates and/or degrading hydrocarbon compounds, which corroborates our metabarcoding data and suggests the presence of microbial members potentially active and involved with degradation of these plastics in the deep sea.

microbiology↗

bioRxiv2019

Short and long TNF-alpha exposure recapitulates canonical astrogliosis events in human induced pluripotent stem cells-derived astrocytes

Astrogliosis comprises a variety of changes in astrocytes that occur in a context-specific manner, triggered by temporally diverse signaling events that vary with the nature and severity of brain insults. However, most mechanisms underlying astrogliosis were described using animal models, which fail to reproduce some aspects of human astroglial signaling. Here, we report an in vitro model to study astrogliosis using human induced pluripotent stem cells (iPSC)-derived astrocytes which replicates aspects temporally intertwined of reactive astrocytes in vivo. We analyzed the time course of astrogliosis by measuring nuclear translocation of NF-kB, secretion of cytokines and changes in morphological phenotypes of human iPSC-derived astrocytes exposed to TNF-. It was observed the NF-kB nuclear translocation, increases either in the inflammation-related cytokines secretion and gene expression for IL-1{beta}, IL-6 and TNF- following 24 h TNF- stimulation. After 5 days, human iPSC-derived astrocytes exposed to TNF- exhibited increases in vimentin and GFAP immunolabeling, elongated shape and shrinkage of nuclei, which is typical phenotypes of astrogliosis. Moreover, about a 50% decrease in D-[3H] aspartate uptake was observed over the astrogliosis course with no evident cell damage, which suggests astrocytic dysfunction. Taken together, our results indicate that cultured human iPSC-derived astrocytes reproduce canonical events associated to astrogliosis in a time dependent fashion. Our findings may contribute to a better understanding of mechanisms governing human astrogliosis. Furthermore, the approach described here presents a potential applicability as a platform to uncover novel biomarkers and new drug targets to refrain astrogliosis associated to human brain disorders.

neuroscience↗