Biology subjects

Bryan, C.

Publications and source records attributed to Bryan, C..

5 recordsLinked to original sources

bioRxiv2026

Microphysiological Flow Batteries For Dynamic EDC Screening Of mESC-derived Thyroid Organoids

Endocrine disrupting chemicals (EDCs) are ubiquitous environmental contaminants capable of dysregulating the production of thyroid hormones. Traditional thyroid toxicological assays rely on 2D cell cultures and animal models, both of which fail to accurately recapitulate human thyroid physiology and provide limited mechanistic insight into EDC toxicity. To overcome these limitations, we report a novel thyroid-on-chip platform integrating mouse embryonic stem cell-derived thyroid organoids with advanced organ-on-chip (OoC) technology and downstream multi-omics analysis. The platform leverages a reversibly-sealed microphysiological flow battery (MFB) to allow scale up of dynamic organoid culture and controlled chemical exposure while reducing operational complexity. Upon EDC exposure, transcriptomic and proteomic analysis revealed new molecular signatures of thyroid disruption across four different EDC classes, even at very low EDC concentrations (1nM), validating the capacity of this system to mechanistically dissect EDC-induced responses. This represents an integrated platform consists of an advanced physiologically relevant assay framework for next-generation endocrine toxicity testing, bridging the gap between in vitro screening and in vivo thyroid physiology.

bioengineering↗

bioRxiv2025

Time-series RNA metabarcoding of the active Populus tremuloides root microbiome reveals hidden temporal dynamics and dormant core members

Dormancy is a key life history stage of many microbes that involves existence in a metabolically inactive state. Although dormant taxa may contribute little to community function, most microbial metabarcoding community surveys of microbial systems target DNA which captures dormant and dead taxa in addition to the active and living fraction of the community. RNA metabarcoding offers the potential to delineate the active fraction of microbial communities. Transitions between dormancy and activity may also serve as a rapid response mechanism for communities for communities to alter their function faster than turnover in community composition. Additionally, a focus on active microbiomes may provide further insight into which taxa should be prioritized as part of the core microbiome. We used DNA and RNA metabarcoding in samples collected as a time-series of the quaking aspen (Populus tremuloides) root microbiome across a natural environmental gradient to identify the degree of spatiotemporal dynamism in active and total microbial communities and to document the extent of dormancy in the core microbiome. We found that active bacterial and fungal communities were more temporally dynamic than total communities, while total communities exhibited a stronger response to spatial variability in site conditions. Additionally, we found that core microbiome members are frequently inactive, resulting in a reduced active core microbiome. This study stresses the need to focus on turnover in the active microbial community to detect variation in microbial communities in time-series and to use microbial activity levels as a key determinant of core microbiome membership.

ecology↗

bioRxiv2022

L-type calcium channels link oxidative stress to calcium signaling pathway and membrane excitability: Insights from computational modeling of dopaminergic neurons

Dopamine neurons, which are critical in movement, cognition, and reward learning, are vulnerable to oxidative stress during aging, drugs of abuse, and viral infection and can lead to neurodegeneration. Previous work used computational modeling to study dopamine neuron function based on experimental findings from rodent brain slices containing dopamine neurons. Here we show for the first time the feasibility and utility of applying such computational models of DA neurons to the analysis of experimental findings from in-vitro cultured cells. We used DCFH-DA (and DHE) and time-lapse, Fura-2 ratiometric imaging to measure changes in ROS levels and changes in intracellular calcium (Ca2+) levels, respectively, in two dopaminergic cell models: differentiated SH-SY5Y and differentiated human neural progenitor cells. We investigated how peroxide-dependent changes in the behavior of the L-type channel might alter the excitability of the dopaminergic cell. We found that L-type channels mediated clusters of calcium spikes (or oscillations) and that our model suggested that such increased excitability could be explained by changes in the voltage-dependence of activation of the L-type channels in response to exogenous peroxide. Our findings suggested that L-type channels link oxidative stress responses to modulation of excitability. We conclude that the Ca2+ channel blocker nicardipine may help disrupt this link by reducing oxidative stress and preventing channel activation at more hyperpolarized potentials, thus reducing plasma membrane excitability.

neuroscience↗

bioRxiv2020

Low Dose Lead Exposure Induces Alterations on Heterochromatin Hallmarks Persisting Through SH-SY5Y Cell Differentiation

Lead (Pb) is a commonly found heavy metal due to its historical applications. Recent studies have associated the early-life Pb exposure with the onset of various neurodegenerative disease. The molecular mechanisms of Pb conferring long-term neurotoxicity, however, is yet to be elucidated. In this study, we explored the persistency of alteration in epigenetic marks that arise from exposure to low dose of Pb using a combination of image-based and gene expression analysis. Using SH-SY5Y as a model cell line, we observed significant alterations in global 5-methycytosine (5mC) and histone 3 lysine 27 tri-methylation (H3K27me3) and histone 3 lysine 9 tri-methylation (H3K9me3) levels in a dose-dependent manner immediately after Pb exposure. The changes are partially associated with alterations in epigenetic enzyme expression levels. Long term culturing (14 days) after cease of exposure revealed persistent changes in 5mC, partial recovery in H3K9me3 and overcompensation in H3K27me3 levels. The observed alterations in H3K9me3 and H3K27me3 are reversed after neuronal differentiation, while reduction in 5mC levels are amplified with significant changes in patterns as identified via texture clustering analysis. Moreover, correlation analysis demonstrates a strong positive correlation between trends of 5mC alteration after differentiation and neuronal morphology. Collectively, our results suggest that exposure to low dose of Pb prior to differentiation can result in persistent epigenome alterations that can potentially be responsible for observed phenotypic changes.

developmental biology↗

bioRxiv2020

Integrated Analysis of Methylome and Transcriptome Following Developmental Atrazine Exposure in Zebrafish Reveals Aberrant Gene-Specific Methylation of Neuroendocrine and Reproductive Pathways

Atrazine (ATZ) is one of the most commonly used herbicides in the United States. Previous studies have hypothesized the role of ATZ as an endocrine disruptor (EDC), and developmental exposure to ATZ has been shown to lead to behavioral and morphological alterations. Specific epigenetic mechanisms responsible for these alterations, however, are yet to be elucidated. In this study, we exposed zebrafish embryos to 0.3, 3, and 30 ppb ({micro}g/L) of ATZ for 72 hours post fertilization. We performed whole-genome bisulfite sequencing (WGBS) to assess the effects of developmental ATZ exposure on DNA methylation in female fish brains. The number of differentially methylated genes (DMG) increase with increasing dose of treatments. DMGs are enriched in neurological pathways with extensive methylation changes consistently observed in neuroendocrine and reproductive pathways. To assess the effects of DNA methylation on gene expression, we integrated our data with transcriptomic data. Four genes, namely CHD9, FRAS1, PID1, and PCLO, were differentially expressed and methylated in each dose. Overall, this study identifies specific genes and pathways with aberrant methylation and expression following ATZ exposure as targets to elucidate the molecular mechanisms of ATZ toxicity and presents ATZ-induced site-specific DNA methylation as a potential mechanism driving aberrant gene expression.

pharmacology and toxicology↗