Biology subjects

Stauffer, S.

Publications and source records attributed to Stauffer, S..

7 recordsLinked to original sources

bioRxiv2025

Zooplankton feeding behaviour and survival to toxic and non-toxic cyanobacteria during the seasonal bloom progression of a eutrophic lake

Harmful cyanobacterial blooms pose increasing threats to aquatic ecosystems and human health; yet, the role of zooplankton grazing in regulating blooms remains understudied. We investigated the seasonal feeding behaviour and fitness consequences of feeding preferences in natural zooplankton communities for toxic (microcystin-producing) versus non-toxic cyanobacteria across temperature gradients in eutrophic Lake Greifen, Switzerland. We conducted monthly experiments from April to October 2023 to test the grazing behaviour of four zooplankton groups (daphnids, calanoid copepods, cyclopoid copepods, and microzooplankton) exposed to mixed diets of green algae and either toxic or non-toxic Microcystis strains at 15{degrees}C and 25{degrees}C. Contrary to expectations of cyanobacteria avoidance, zooplankton exhibited predominantly non-selective grazing throughout the seasonal succession, consuming both toxic and non-toxic cyanobacteria at similar rates, regardless of temperature. Notably, during the peaks of phytoplankton abundance (April and September), mesozooplankton demonstrated a selective preference for cyanobacteria over green algae, particularly non-toxic strains. Temperature effects were subtle but revealed metabolic constraints: elevated temperatures occasionally triggered selective consumption of cyanobacteria in copepods, while fitness costs (survival) from exposure to toxic species were mostly restricted to transitional bloom periods and high-temperature conditions. These findings suggest that toxic cyanobacteria may not always evade grazing pressure through secondary metabolite deterrent effects. Our results suggest that zooplankton communities can adapt and graze on cyanobacteria regardless of toxicity under the tested conditions, even during bloom conditions. These observations highlight the potential for zooplankton to interact with cyanobacterial populations, which may have implications for bloom prediction and management strategies, particularly under climate warming scenarios. Manuscript HighlightsO_LIZooplankton grazed on toxic and non-toxic cyanobacteria with similar effects across seasons in a eutrophic lake characterised by toxic blooms. C_LIO_LINatural zooplankton communities showed no systematic avoidance of microcystin-producing cyanobacteria. C_LIO_LIHigh temperature effects on feeding selectivity were subtle and taxon-specific. C_LIO_LIFitness costs from exposure to cyanobacteria (including microcystin-producing isolates) were rare and occurred only during transitional bloom periods. C_LIO_LIResults suggest that zooplankton communities may be adapted to cyanobacterial blooms, even when dominated by toxic species. C_LI

ecology↗

bioRxiv2025

Dysregulation of innate immunity and cellular metabolism through virus-induced deISGylation

Interferon-stimulated gene 15 (ISG15) regulates diverse cellular responses including antiviral immunity through its conjugation to proteins, a process known as ISGylation. Several pathogens, including SARS-CoV-2, subvert ISGylation by encoding deISGylating enzymes. However, the direct targets and physiological consequences of coronaviral deISGylation remain poorly defined. Here, we ablated the deISGylating activity of the SARS-CoV-2 papain-like protease (PLpro) and found that loss of deISGylation boosted innate immune activation, attenuated virus replication, and promoted viral clearance in human cells and in mice. Through untargeted metabolomics and ISGylome proteomics analyses, combined with functional studies, we discovered in molecular detail how the activities of key metabolic enzymes in glycolysis, the pentose phosphate pathway, and oxidative stress are controlled by PLpro deISGylation. These findings provide fundamental new insight into how reversible ISGylation regulates immunity and metabolic processes at the molecular level and highlight viral deISGylation as a major viral tactic for rewiring immunometabolism.

microbiology↗

bioRxiv2025

Adenine-induced kidney disease alters the cortical bone metabolome of C57BL/6J mice in a manner that depends on sex

Chronic kidney disease (CKD) increases the likelihood of bone fracture as well as post-fracture mortality. The loss of bone fracture resistance in CKD results from both a loss of bone mass and decreased bone material properties, which together result from changes to the health and activities of bone cells. Determining changes to bone tissue metabolism with CKD may reveal insights important to monitoring and mitigating the decrease in bone fracture resistance that commonly occurs as a result of this disease. In this study, untargeted metabolomics was conducted on marrow-flushed cortical tibiae from female and male C57BL/6J mice fed either a control or 0.2% w/w adenine diet. The diets were continued over 3.5 or 7 weeks to produce different severities of kidney injury. Liquid chromatography mass spectrometry (LC-MS) was used to assess metabolites from tibia extracts. Group comparisons (CKD vs control, 7 weeks vs 3.5 weeks, female vs male) were conducted using principal components analysis (PCA), partial least squares discriminant analysis (PLS-DA), and hierarchical clustering. Clusters of metabolites were also assessed using ensemble clustering and cluster optimization analysis (ECCO). Volcano plots and VIP scores were used to identify individual metabolites that differed between groups. Pathway analyses were then conducted from these metabolites. The CKD mice, compared with control mice, had dysregulated essential and nonessential amino acid pathways along with altered pathways associated with sugar and fatty acid metabolism. Compared with mice fed an adenine diet for 3.5 weeks, the mice fed an adenine diet over 7 weeks showed dysregulations in the pentose phosphate pathway along with essential and nonessential amino acid metabolism, porphyrin metabolism, steroid hormone biosynthesis, and other pathways relevant to energy production. Sex differences were apparent in the bone tissue metabolomes of females and males. Compared to males, females experienced dysregulations in essential and nonessential amino acid pathways along with other pathways associated with energy derivation, such as pantothenate and CoA biosynthesis. These results demonstrate that CKD alters bone tissue metabolism and reveals novel insights into metabolic dysregulation in disease as well as important sex differences in these metabolic processes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=164 SRC="FIGDIR/small/657438v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@eb7e57org.highwire.dtl.DTLVardef@b3875aorg.highwire.dtl.DTLVardef@7b5c70org.highwire.dtl.DTLVardef@f1d5ed_HPS_FORMAT_FIGEXP M_FIG C_FIG (A) Generalized group comparisons utilizing Partial Component Analysis (PCA), Partial Least Squares-Discriminant Analysis (PLS-DA), and Hierarchical Cluster Analysis (HCA). (B) Pathway analysis utilizing volcano plots and VIP scores plots. (C) Pathway analysis results for comparisons between adenine-induced CKD and control groups, 7-week and 3.5-week diet groups, and female and male groups. A red arrow denotes a set of pathways that were downregulated, a black arrow denotes a set of pathways that were upregulated, and a gray arrow denotes a category of pathways that contained both upregulations and downregulations.

biochemistry↗

bioRxiv2024

Targeting an Olfactory Receptor Mitigates High Residual Platelet Reactivity and Arterial Thrombosis Through Actin Cytoskeleton Depolymerization

BackgroundDespite antiplatelet therapy, some patients remain at high risk for ischemic events due to medication non-responsiveness or High Residual Platelet Reactivity (HRPR). Our goal was to target an orphan G-Protein-Coupled Receptor (GPCR) on platelets belonging to the olfactory receptor family as a new antithrombotic strategy. MethodsUsing an engineered reporter cell line expressing Olfactory Receptor 2L13 (OR2L13) that was recently identified as an orphan GPCR to limit platelet reactivity, we performed a high-throughput screen (HST) of non-odorant bioactive compounds with counter-screen validation, followed by studies to determine changes in platelet function in healthy subjects and in patients with coronary artery disease and peripheral artery disease. Phospho-proteomics identified key signal transduction pathways, and a variety of ex vivo assays and in vivo functional studies examined the impact of an identified non-odorant compound on platelet signaling, platelet biomechanics, and thrombosis. ResultsWe identified 6 ligands specific for OR2L13 that function as receptor agonists, leading to the suppression of platelet aggregation and -granule exocytosis via P2Y12, PAR1, Thromboxane Receptor (TxR) and glycoprotein VI (GPVI) receptors, suggesting involvement of common downstream mediator. The lead OR2L13 agonist identified phosphorylates heat shock protein 27 (HSP27) and depolymerizes the platelet filamentous actin cytoskeleton which was further confirmed in a clot retraction assay (CCF0054500 clot area 70.6 vs. vehicle clot area 5.2, P<0.0001). This anti-thrombotic effect of the OR2L13 agonist was reversed by a HSP27 inhibitor (clot area 3.6, P<0.0001). In a murine cremaster arterial injury model, platelet accumulation at the injury site was reduced by 88.9% by the lead OR2L13 agonist compared to vehicle (P<0.0003) without altering fibrin generation in vivo, or interfering with the coagulation cascade, and without impairing the protective mechanism of platelet hemostasis. ConclusionWe describe and characterize the first non-olfactory tool to target an olfactory receptor for the purpose of inhibiting platelet activation and thrombosis through downstream HSP27 in a comprehensive investigation using a first-of-its kind platelet inhibitor targeting an orphan platelet GPCR.

physiology↗

bioRxiv2024

A Second Drug Binding Site in P2X3

Purinergic P2X3 receptors form trimeric cation-gated channels, which are activated by extracellular ATP. P2X3 plays a crucial role in chronic cough and affects over 10% of the population. Despite considerable efforts to develop drugs targeting P2X3, the highly conserved structure within the P2X receptor family presents obstacles for achieving selectivity. Camlipixant, a potent and selective P2X3 antagonist, is currently in phase III clinical trials. However, the mechanisms underlying receptor desensitization, ion permeation, principles governing antagonism, and the structure of P2X3 when bound to camlipixant remain elusive. In this study, we established a stable cell line expressing homotrimeric P2X3 and utilized a peptide scaffold to purify the complex and determine its structure using cryo-electron microscopy (cryo-EM). P2X3 binds to camlipixant at a previously unidentified drug-binding site and functions as an allosteric inhibitor. Structure-activity studies combined with modeling and simulations have shed light on the mechanisms underlying the selective targeting and inhibition of P2X3 by camlipixant, distinguishing it from other members of the P2X receptor family.

biochemistry↗

bioRxiv2021

Peripheral sTREM2-related inflammatory activity alterations in early stage Alzheimer's disease

Alzheimers disease (AD) has been linked to multiple immune system genetic variants, implicating potential broad alterations in inflammatory profiles in the disease. Triggering receptor expressed on myeloid cells 2 (TREM2) genetic variants are risk factors for AD and other neurodegenerative diseases. A soluble TREM2 isoform (sTREM2) is elevated in cerebrospinal fluid in the early stages of AD suggesting it may be a biomarker of progressive alterations in immune response to AD-related pathology. Multiple studies have reported an altered peripheral immune response in AD. However, less is known about the relationship between plasma sTREM2 and the altered peripheral immune response in AD. The objective of this exploratory study was to examine the relationship between sTREM2 and inflammatory activity in human participants defined by clinically characterized cognitive symptoms and groups defined by the cerebrospinal fluid biomarkers amyloid beta, phosphorylated tau, and neurodegeneration (NIA-AA Research Framework: "ATN continuum".) The hypothesis of this exploratory study was that sTREM2 related inflammatory activity differs by AD stage. We observed different patterns of inflammatory activity across disease groups and ATN categories that implicates peripheral sTREM2 related inflammatory activity as altered in the early stages of AD. Notably, fractalkine showed a significant relationship with sTREM2 across different analyses in the control groups that was lost as disease progressed, and fractalkine, IL-5 and IL-17A were decreased in AD. These preliminary data provide important support to the hypothesis that sTREM2-related inflammatory activity is a stage-specific biomarker of AD progression, providing the groundwork for future studies and therapeutic strategies.

neuroscience↗

bioRxiv2021

How many replicates to accurately estimate fish biodiversity using environmental DNA on coral reefs?

Quantifying the diversity of species in rich tropical marine environments remains challenging. Environmental DNA (eDNA) metabarcoding is a promising tool to face this challenge through the filtering, amplification, and sequencing of DNA traces from water samples. However, the reliability of biodiversity detection from eDNA samples can be low in marine environments because eDNA density is low and certainly patchy in this vast, heterogenous and dynamic environment. So, the number of sampling replicates and filtered volume necessary to obtain accurate estimates of biodiversity in rich tropical marine environments using eDNA metabarcoding is still unknown. Here, we used a paired sampling design of 30L per replicate on 68 reef transects from 8 sites in three tropical regions and identified fish Molecular Taxonomic Units (MOTUs) using a 12S marker. We quantified local biodiversity variation as MOTU richness, compositional turnover and compositional nestedness between replicated pairs of seawater samples. We report strong turnover of MOTUs between replicated pairs of samples undertaken in the same location, time, and conditions. Paired samples contained non-overlapping assemblages rather than subsets of one-another. As a result, localised diversity accumulation curves showed that even 6 replicates (180L) in the same location underestimated local diversity (for an area <1km). However, sampling of regional diversity using [~]25 replicates in variable locations (often covering 10s of km) achieved saturation of biodiversity accumulation curves. Our results demonstrate high variability of diversity estimates perhaps arising from heterogeneous and local distribution of eDNA distribution in seawater or highly skewed frequencies of eDNA traces. This high compositional variability has consequences for using eDNA to monitor temporal and spatial biodiversity changes of local assemblages. Future biomonitoring efforts could be strongly undermined by a high level of false-negative detections under low replication protocols. We reveal the need to increase replicates or increase sampled water volume to better inform management of marine biodiversity using eDNA.

ecology↗