Biology subjects

Pierce, M.

Publications and source records attributed to Pierce, M..

6 recordsLinked to original sources

bioRxiv2026

Sex-specific associations of childhood adversity with frontostriatal network organization and anhedonia in young adulthood

IntroductionAnhedonia is a transdiagnostic psychiatric symptom linked to increased functional connectivity between the prefrontal cortex and striatum. Here, we examined how dimensions of early adversity contribute to this profile of connectivity. MethodsIn a European community sample of young adults (IMAGEN), we examined cross-sectional (n=613) and longitudinal (n=332) associations of adversity dimensions with resting-state fMRI-derived connectivity. We selected 10 ROIs from anhedonia literature, defined in the functional images as 4mm-radius spheres. We then used network-based regression models to identify clusters of ROI-ROI connections associated with threat and deprivation scores, using interaction terms to examine sex and age-specific associations. We also examined associations between adversity and anhedonia, operationalized using factor analysis of six items from self-report surveys. ResultsAt age 18-22, we identified sex-specific associations between deprivation and connectivity for a cluster of 9 ROI-ROI connections (p-FWE=0.038), primarily involving the nucleus accumbens. Specifically, we observed positive associations between deprivation and connectivity in males, and negative associations in females. In the longitudinal analysis, negative deprivation associations in females attenuated with age for a cluster of 14 connections (p-FWE=0.009). A cluster of 17 connections also had initial positive associations with threat in females that attenuated with age (p-FWE=0.008). No such longitudinal changes were observed in males. Higher deprivation was linked to increased later anhedonia in males but not females (p=0.026). ConclusionCompared to females, young adult males may be more vulnerable to developing anhedonia after experiencing deprivation in childhood. Dimensions of early adversity are linked to distinct pathways of frontostriatal development.

neuroscience↗

bioRxiv2026

A screen for stress-induced sleep genes in C. elegans reveals a role for glutamate signaling

Sleep is an essential behavioral state that evolved early in animals, possibly with the advent of the nervous system. The complexity of sleep neural networks varies significantly across phylogeny, yet common signaling molecules exist. Stress-induced sleep (SIS) of Caenorhabditis elegans is controlled by two sleep interneurons (ALA and RIS), within a 302-celled nervous system. Even in this simple framework, a complex array of signaling molecules is expressed. Here, we surveyed some of these genes for roles in SIS. These included neuropeptides, g-protein coupled receptors, a two-pored potassium channel, and glutamate signaling components. We found that multiple genes are required for sleep maintenance (i.e., amounts), and/or the precise timing of sleep initiation. In particular, we identified an important role for glutamate signaling. The conserved ionotropic glutamate receptor glr-5, regulates sleep maintenance and timing, and is required in a 3-celled circuit of interneurons connected by gap junctions and chemical synapses with RIS. This work suggests that numerous redundant and/or parallel mechanisms have evolved to modulate a simple sleep-regulating circuit in C. elegans, and we speculate that conserved pathways may play similar roles in animals with more complex systems.

genetics↗

bioRxiv2025

LAP Drives Monocyte-Mediated and Extracellular Translocation of Listeria monocytogenes Across the Placental Barrier

Listeria monocytogenes (Lm) is a major cause of fetal infection, yet the mechanisms by which it traverses the placental barrier remain incompletely defined. We established and validated a physiologically relevant in vitro human placental co-culture barrier model using BeWo trophoblasts and primary human placental vascular endothelial cells (HPVECs), which exhibited robust barrier integrity and organized tight junctions. Using this model, we demonstrate that Lm exploits a Trojan-horse transmigration mechanism via infected monocytes. Lm-infected THP-1 monocytes displayed a [~]4.8-fold higher monocyte transmigration and [~]8.12-fold greater intracellular bacterial delivery across the placental barrier compared with non-pathogenic Listeria innocua (Li). Monocyte transmigration was associated with claudin-1 and occludin disruption, increased paracellular permeability, and localization of infected monocytes at junctional breach sites. Monocyte-mediated placental traversal required the Lm virulence factors Listeria adhesion protein (LAP) and internalin B (InlB), as lap- and{Delta} inlB mutants exhibited Li-like transmigration and an [~]90% reduction in intracellular bacterial delivery, despite normal monocyte uptake. Lm-infected monocytes induced a [~]1.86-fold increase in sVCAM-1 secretion, which was LAP- and InlB-dependent, consistent with pro-transmigration endothelial phenotype. In contrast, extracellular traversal required LAP and internalin A (InlA), as lap- and{Delta} inlA mutants exhibited severe defects comparable to Li, whereas{Delta} inlB and{Delta} hly were minimally impaired. Exposure of monocytes to extracellular Lm further amplified transmigration and barrier permeability. Together, these data define two distinct placental invasion routes: a monocyte-associated LAP/InlB-dependent pathway and an extracellular LAP/InlA-dependent pathway, identifying LAP as a critical noncanonical virulence factor in placental infection and mechanisms of vertical transmission.

microbiology↗

bioRxiv2025

Rapid, Efficient Candida albicans Lysis Comparison Using the Cellometer X2 Fluorescent Cell Viability Counter

Cell lysis is essential for extracting intake genetic material, forming the basis for diagnostic tests, and genetic studies. Commonly used lysis methods include thermal lysis, mechanical force, chemicals, biologicals, and sonication. Determining effective lysis methods for specific cell types is crucial for conducting further research. This study evaluates the lysis efficiency of Candida albicans using the Cellometer X2 fluorescent cell viability counter, employing various lysis methods: thermal, chemical, and enzymatic. Our results indicate that high-pH buffers combined with heat treatment enhance lysis efficiency, while SDS alone or with Proteinase K is insufficient for lysis at room temperature. In contrast, Zymolyase effectively lyses C. albicans at room temperature in 150 minutes, making the automation of room temperature lysis and nucleic acid purification feasible for C. albicans. Overall, this study highlights the Cellometer X2s capability for rapid and direct evaluation of cell lysis efficiency.

microbiology↗

bioRxiv2022

Dinoflagellate Proton-Pump Rhodopsin Gene in Long Island Sound: Diversity and Spatiotemporal Distribution

Microbial proton-pump rhodopsin (PPR), an alternative light-harvesting mechanism to chlorophyll-based photosystems, may contribute significantly to solar energy entry into the marine ecosystem. PPR transforms solar energy to cellular energy used for various metabolic processes in the cells or flagellar movement. Although rhodopsins or their encoding genes have been documented in a wide phylogenetic range of cultured dinoflagellates, information is limited about how widespread and how spatiotemporally dynamical dinoflagellate PPR (DiPPR) are in the marine ecosystem. In this study, using the quantitative PCR method, we investigated the abundance and diversity of DiPPR genes in Long Island Sound (LIS), a temperate estuary, both spatially and temporally in 2010. DiPPR genes were found year-round and throughout LIS, with higher abundances in the eutrophic Western Sound and during April and July. The gene diversity data suggest that there are at least five distinct rhodopsin-harboring groups of dinoflagellates throughout the year. The abundance of DiPPR genes, measured as copy number per mL seawater, appeared not to be influenced by water temperature and nitrogen nutrient concentration; however, weak negative correlations with orthophosphate concentration and salinity and a positive correlation with the abundance of typical-DiPPR-harboring dinoflagellates were observed. The association of DiPPR with phosphorus nutrition warrants further studies.

molecular biology↗

bioRxiv2020

The epithelial-mesenchymal transcription factor SNAI1 represses transcription of the tumor suppressor miRNA let-7 in cancer

We aimed to determine the mechanism of epithelial-mesenchymal transition (EMT)-induced stemness in cancer cells. Cancer relapse and metastasis are caused by rare stem-like cells within tumors. Studies of stem cell reprogramming have linked let-7 repression and acquisition of stemness with the EMT factor, SNAI1. The mechanisms for the loss of let-7 in cancer cells are incompletely understood. In four carcinoma cell lines from breast cancer, pancreatic cancer and ovarian cancer and in ovarian cancer patient-derived cells, we analyzed stem cell phenotype and tumor growth via mRNA, miRNA, and protein expression, spheroid formation, and growth in patient-derived xenografts. We show that treatment with EMT-promoting growth factors or SNAI1 overexpression increased stemness and reduced let-7 expression, while SNAI1 knockdown reduced stemness and restored let-7 expression. Rescue experiments demonstrate that the pro-stemness effects of SNAI1 are mediated via let-7. In vivo, nanoparticle-delivered siRNA successfully knocked down SNAI1 in orthotopic patient-derived xenografts, accompanied by reduced stemness and increased let-7 expression, and reduced tumor burden. Chromatin immunoprecipitation demonstrated that SNAI1 binds the promoters of various let-7 family members, and luciferase assays revealed that SNAI1 represses let-7 transcription. In conclusion, the SNAI1/let-7 axis is an important component of stemness pathways in cancer cells, and this study provides a rationale for future work examining this axis as a potential target for cancer stem cell-specific therapies. Novelty and ImpactThis study provides new insight into molecular mechanisms by which EMT transcription factor SNAI1 exerts its pro-stemness effects in cancer cells, demonstrating its potential as a stem cell-directed target for therapy. In vitro and in vivo, mesoporous silica nanoparticle-mediated SNAI1 knockdown resulted in restoration of let-7 miRNA, inhibiting stemness and reducing tumor burden. Our studies validate in vivo nanoparticle-delivered RNAi targeting the SNAI1/let-7 axis as a clinically relevant approach.

cancer biology↗