Biology subjects

Carpentier, A.

Publications and source records attributed to Carpentier, A..

8 recordsLinked to original sources

bioRxiv2026

Focal Neurostimulation of Calcium Signaling and Dopamine Release in Human Dopaminergic Neurons Using Megahertz-range Single-Pulse Focused Ultrasound

Focused Ultrasound (FUS) neurostimulation has increasingly attracted attention given its ability for localized targeting and non- to minimally-invasive capacity. However, the understanding of the biological and neurochemical mechanisms triggered by this neurostimulation modality remains limited. Indeed, further progress of this technology could benefit from spatiotemporal evaluation of neurotransmitter secretory activity resulting from FUS stimulation. Recently, we demonstrated in-vitro the ability of FUS to evoke calcium (Ca2+) waves, in a mixture of human neuronal and glial cells (standard cells), with single-pulse megahertz-range FUS compatible with a transdural approach relying on an intracranial FUS implant. In the present work, we investigated the ability to evoke Ca2+ signaling and dopamine (DA) release by single-pulse megahertz-range FUS stimulation of cultured human dopaminergic neurons in-vitro. A hybrid-platform integrating a custom-made FUS implant prototype (concave spherical transducer, O and focal distance: 15 mm) with real-time Ca2+ fluorescence microscopy imaging (FMI), and fast scan cyclic voltammetry (FSCV) was constructed to evaluate FUS-evoked Ca2+ signaling and concurrent DA release. Ca2+ and DA releases evoked by FUS on dopaminergic neurons (DA neurons) were compared to those evoked in standard cells. Application of single-pulse FUS (frequency: 5.11 MHz, pulse duration: 700 {micro}s, spatial average pulse average intensity, Isapa: 19.59 {+/-} 4.12 W.cm-2) was shown to causally mobilize Ca2+ dynamics in both cell types. Immediate (< 1 s) responses were focally evoked in cell clusters of 290 {micro}m in diameters; corresponding to the -3 dB FUS focal diameter. However, while standard cells exhibited continuous and omnidirectional delayed propagating dynamics following FUS stimulation, DA neurons showed more spatially sparse responses. The FUS-induced Ca2+ activity in DA neurons was accompanied by DA release detected by FSCV, but not in standard cells. This study demonstrates that single-pulse megahertz-range FUS induced with an intracranial implant prototype smaller than conventionally used FUS devices (transcranial applications) can evoke in-vitro intracellular Ca2+ activity while stimulating DA release from dopaminergic neurons, underscoring its potential as a neuro-stimulation/-modulation tool for targeting dopaminergic circuits in various pathologies.

bioengineering↗

bioRxiv2025

A Multi-Taxa Approach to Estuarine Biomonitoring: Assessing Vertebrate Biodiversity and Ecological Continuity using Environmental DNA Metabarcoding in the Rance River (Brittany, France)

Estuaries are ecologically vital yet highly impacted ecosystems that serve as transitional zones between land and sea. Monitoring their biodiversity is essential but challenging due to their dynamic nature and the transient presence of many species. Traditionally actinopterygian monitoring in these systems still relies on conventional and intrusive methods such as gill nets and trawls. Environmental DNA (eDNA) metabarcoding offers a non-invasive, multi-taxa alternative that can complement these traditional approaches. Here, we applied an eDNA-based metabarcoding approach to characterize vertebrate diversity in the Rance Estuary, located in the Brittany Region of France. Water samples were collected from five stations spanning marine to freshwater environments. Special attention was given to two stations located upstream and downstream of the tidal power plant (TPP) dam to assess its potential impact on ecological continuity. We detected a total of 124 distinct vertebrate MOTUs--comprising actinopterygians, birds, mammals, and amphibians. Taxonomic composition followed the estuarine gradient, with Jaccard dissimilarity increasing with distance from the sea and largely driven by species turnover. While taxonomic and phylogenetic diversity remained relatively stable across the vertebrate community, functional diversity revealed an increasing terrestrial influence. For actinopterygians, taxonomic diversity decreased upstream, whereas phylogenetic and functional diversity indicated fine-scale structuring, even among nearby stations. This approach enabled the development of biodiversity metrics and facilitated comparisons with previous actinopterygian monitoring surveys in the same area based on conventional methods (scientific fishing using nets and dredges). Our results emphasise the potential of eDNA for holistic estuarine biomonitoring and establish a valuable baseline for future non-invasive assessments.

ecology↗

bioRxiv2025

Respiratory syncytial virus load-dependent ciliated cell dedifferentiation and downregulation of immune response genes

Respiratory syncytial virus (RSV) can cause severe lower respiratory tract infections in infants, older adults, and individuals with chronic or immunocompromising conditions. To understand how RSV affects airway cells, we infected primary human airway epithelial cultures with RSV and analyzed infected and bystander cells using time-resolved single-cell RNA sequencing and imaging. RSV mainly infected ciliated cells, triggering a virus load-dependent shutdown of genes involved in ciliogenesis, antigen presentation, and innate sensing, including key interferon (IFN) and pattern recognition pathways. Only a subset of infected cells produced type I and III IFNs, while bystander cells exhibited strong IFN-stimulated gene (ISG) signatures. Neither IFN treatment nor ISG induction eliminated infection, but IRF1, an antiviral transcription factor not suppressed by RSV, remained robustly expressed. Ectopic IRF1 expression in vitro reduced viral replication. These findings reveal how RSV evades antiviral defenses and highlight IRF1 as a potential target for therapeutic intervention.

microbiology↗

bioRxiv2025

Focal neurostimulation of propagating calcium waves in human neural cells using megahertz-range single-pulse focused ultrasound

Focused ultrasound (FUS) offers a promising neurostimulation technique that addresses the trade-off between invasiveness and spatial selectivity found in conventional electromagnetic-based methods. Evidence supporting its theoretical selectivity and comprehensive descriptions of the underlying biophysical mechanisms remain insufficient to ensure adequate control and safety. Based on observations of causal, focal, and propagating calcium waves in human neural cells in vitro evoked using single-pulse megahertz-range FUS, a transdural FUS approach relying on an intracranial implant is proposed to overcome frequency limitations associated with transcranial ultrasound. Using an extended parameter space (0.7 -8 MHz), calcium waves were shown to be selectively elicited by cavitation or acoustic radiation force. Cavitation, predominant at frequencies under 5 MHz, induced dispersed and unpredictable responses that could lead to cell damage. FUS radiation force however, predominant at frequencies over 5 MHz, elicited focal and predictable responses, without affecting cell viability. FUS-evoked intercellular calcium waves were shown to propagate across the surrounding neural network via intracellular and extracellular pathways driven by calcium amplification mechanisms. Collectively, these findings lay the foundation for developing wearable neurostimulation approaches to manage chronic neurological conditions.

bioengineering↗

bioRxiv2025

Repeated blood-brain barrier opening using low-intensity pulsed ultrasound mitigates amyloid pathology

BackgroundThe delivery of large molecules to the pathological brain is one of the main obstacles in the development of disease-modifying drugs. This is partly due to the presence of the blood-brain barrier (BBB), which blocks the free passage of lipophobic molecules and those larger than 400 Da. One strategy to bypass this natural barrier is to use low intensity pulsed ultrasound (LIPU) to oscillate circulating micro-sized microbubbles which then exert mechanical stress on the vessel walls. This procedure allows for temporary disruption of the BBB and enhanced local delivery of therapeutics from the blood to the brain parenchyma. In this study, the effect of repeated BBB opening on neuroinflammation in a healthy mouse model was first explored followed by the effect of repeated opening on amyloid pathology in a model for Alzheimers disease. MethodsA cohort of wildtype mice was used to determine the effect of a single BBB opening session mediated by ultrasound/microbubbles (US/MB) on the inflammatory profile, using RT-Q-PCR on brain extracts at 2-, 4-, 8- and 15-days post opening. A second cohort of ARTE10 mice, a mouse model for amyloid pathology, was treated with a different sequence of repeated US/MB mediated BBB opening to explore the effect on the pathology. Tissues were also analyzed for immune cell infiltration, microglia and astrocyte activation, and inflammatory response. ResultsOur results demonstrate that the opening of the BBB leads to a mild inflammatory response in wild-type animals. However, repeated opening of the BBB in the ARTE10 model resulted in a mild decrease in amyloid pathology, along with a mild increase of growth factor. ConclusionsAltogether, this study suggests that sonication is not only a safe method to deliver therapeutics to the brain but could also have synergistic effects in the treatment of neurodegenerative diseases.

neuroscience↗

bioRxiv2023

CLN3 deficiency leads to neurological and metabolic perturbations during early development

Juvenile Neuronal Ceroid Lipofuscinosis (or Batten disease) is an autosomal recessive, rare neurodegenerative disorder that affects mainly children above the age of 5 years and is most commonly caused by mutations in the highly conserved CLN3 gene. Here, we generated cln3 morphants and stable mutant lines in zebrafish. Although neither morphant nor mutant cln3 larvae showed any obvious developmental or morphological defects, behavioral phenotyping of the mutant larvae revealed higher basal activity, hyposensitivity to abrupt light changes and hypersensitivity to pro-convulsive drugs. Importantly, in-depth metabolomics and lipidomics analyses revealed significant accumulation of several glycerophosphodiesters (GPDs) and a global decrease of bis(monoacylglycero)phosphate (BMP) species, two classes of molecules previously proposed as potential biomarkers for CLN3 disease based on independent studies in other organisms. We could also demonstrate GPD accumulation in human-induced pluripotent stem cell-derived cerebral organoids carrying a pathogenic variant for CLN3. Our models revealed that GPDs accumulate at very early stages of life in the absence of functional CLN3 and highlight glycerophosphoinositol and BMP as promising biomarker candidates for pre-symptomatic CLN3 disease.

molecular biology↗

bioRxiv2022

Hepatitis D virus infection of stem cell-derived hepatocytes triggers an IFN- and NFkB-based innate immune response unable to clear infection.

Human pluripotent stem cell-derived hepatocyte-like cells (HLCs) are a valuable model to investigate host-pathogen interactions of hepatitis viruses in a mature and authentic environment. Here, we investigated the susceptibility of HLCs to the Hepatitis D Virus (HDV), a virus that in co-infection with HBV is responsible for the most severe form of viral hepatitis. Cells undergoing hepatic differentiation became susceptible to HDV infection after acquiring expression of the Na+-taurocholate cotransporting polypeptide (NTCP), the receptor mediating HBV and HDV entry. Inoculation of mature HLCs with HDV lead to increasing amounts of intracellular HDV RNA and accumulation of the HDV antigen in the cells. The infection was abrogated when using known entry inhibitors targeting NTCP or by disrupting genome replication using the nucleoside analogue Ribavirin. Upon infection, the HLCs mounted an innate immune response based on induction of the interferons IFNB and L, but not IFNA, and were associated with an upregulation of interferon-stimulated genes. The intensity of this immune response positively correlated with the level of viral replication and was dependant on both the JAK/STAT and NF{kappa}B pathway activation. Importantly, neither this innate immune response nor an exogenous treatment of IFN2b inhibited HDV replication. However, pre-treatment of the HLCs with IFN2b reduced viral infection, suggesting that ISGs may limit early stages of infection. This novel HDV in vitro infection model represents a valuable tool for studying HDV replication and investigating candidate antiviral drugs in cells displaying mature hepatic functions. Lay summaryHDV can infect stem cell-derived hepatocytes through an NTCP-mediated entry process. Infection triggers an IFN and NF{kappa}B dependent innate immune response. However, viral replication seems unaffected by this innate response or by exogenous IFN treatment. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/502443v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@44ca7forg.highwire.dtl.DTLVardef@4a7be3org.highwire.dtl.DTLVardef@b9c3corg.highwire.dtl.DTLVardef@3e66c3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

Changes in salt-marsh vegetation weakly affect top consumers of aquatic food webs

Salt marshes are under high, and increasing, anthropogenic pressures that have notably been reported to affect the diet of several fish species, probably resulting in nursery function alterations. Most of the previous studies in Europe were yet based on gut content analysis of fish, which can be considered a snapshot of immediate impacts of salt-marsh changes, and hardly of long-term effects of disturbances. In this study, we investigated the impact of vegetation type (resulting from both plant invasion and sheep grazing) by assessing trophic network (and especially fish diet and position) of different salt-marsh conditions. Replicated samples of basic sources (particular organic matter and microphytobenthos), dominant vegetation, potential aquatic and terrestrial prey and fish of 3 main species were taken during summer 2010 in two bays from Western France (Mont -Saint-Michel Bay and Seine Estuary) and analysed using C and N stable isotope compositions. All response variables tested (overall trophic organization, trophic niche and trophic position) provided consistent results, i.e. a dominant site effect and a weaker effect of vegetation type. Site effect was attributed to differences in anthropogenic Nitrogen inputs and tidal regime between the two bays, with more marine signatures associated with a higher frequency of flooding events. A second hypothesis is that E. acuta, which has recently totally replaced typical salt-marsh vegetation in Mont Saint-Michel Bay strongly impacted the nursery function. The trophic status of dominant fish species was unchanged by local salt-marsh vegetation, and considered consistent with their diet, i.e. high for predatory species (the sea bass Dicentrarchus labrax and the common goby Pomatoschistus microps) and lower for biofilm grazing species (the thinlip mullet Chelon ramada). This study finally highlights the relevance of stable isotopes analyses for assessing long-term and integrative effects of changes in vegetation resulting from human disturbances in salt marshes. HighlightsO_LICross-ecosystem subsidies are of high functional importance, notably in salt marshes C_LIO_LIFish are vectors of exchanges, most European studies being based on their gut content C_LIO_LIUsing stable isotopes we analysed the effect of surrounding vegetation on food webs C_LIO_LISurprisingly we found weak vegetation and strong site effects on all metrics C_LIO_LINitrogen inputs, site accessibility and loss of nursery function can explain this fact C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/222406v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@27b54borg.highwire.dtl.DTLVardef@ef583corg.highwire.dtl.DTLVardef@18a0303org.highwire.dtl.DTLVardef@1cbe5d4_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗