Toxins

Bacillus thuringiensis (Bt) is currently the most commercialized biopesticide worldwide. Despite the success of Bt application in biological control programs, diverse strategies have been developed to enhance the toxicity of Bt toxins and delay the emergence of insect resistance, including the addition of cadherin fragments as a synergistic agent. In this study, the synergistic effect of two different cadherin fragments, one from a lepidopteran species, Spodoptera exigua (rSeCad1bp), and the other from a coleopteran species, Tenebrio molitor (rTmCad1p), was evaluated on the toxicity of Cry1Aa, Cry1Ab, and Cry1Ia against S. exigua and Grapholita molesta. Our results show that while the toxicity of Cry1 proteins to S. exigua was not affected by rSeCad1bp, the toxicity of Cry1Aa against G. molesta increased about 2.6-fold. No other synergistic or antagonist effects were observed. The potential mechanisms for the detected toxicity enhancement in G. molesta were studied, including protection against proteolysis, promotion of oligomerization, and increased binding to receptors on midgut brush border membrane vesicles (BBMV). Results revealed a slight increase in Cry1Aa binding to BBMV. These data highlight the great potential of using rSeCad1bp in combination with Cry1Aa for control of G. molesta. Key ContributionOur results show that the cadherin fragment from Spodoptera exigua synergized Cry1Aa toxicity against Grapholita molesta, but not to S. exigua. The synergistic effect observed might be partly associated with an increase in Cry1Aa binding to the target midgut membrane.

Symptoms of Clostridioides difficile infection (CDI) are primarily caused by two major protein toxins, toxin A (TcdA) and toxin B (TcdB). In addition, approximately 5-30% of C. dif[fi]cile strains produce a third toxin, C. difficile binary toxin (CDT), which is has been associated with enhanced virulence and severe disease. CDT consists of an enzymatic component CDTa, and a binding and translocation component CDTb, which mediates the delivery of CDTa into host cells. CDTb contains two receptor-binding domains, RBD1 and RBD2. Recent structural studies suggest that RBD2 plays a critical role in the formation and stabilization of the di-heptameric CDTb assembly required for efficient intoxication of host cells. In this study, we evaluated the immunogenicity and protective potential of RBD1 and RBD2 using in silico, in vitro and in vivo approaches. Sequence analysis demonstrated that RBD2 is highly conserved among diverse CDT-producing C. difficile ribotypes and toxinotypes. Immunization of mice with RBD2, but not RBD1 conferred effective protection against direct CDT challenge. Moreover, RBD2 immunization protected hamsters against infection with a CDT-only-producing C. difficile strain (DSM 101085; TcdA-TcdB-CDT). Mechanistically, anti-RBD2 serum, but not anti-RBD1 serum, effectively neutralized CDT-mediated cytotoxicity, as demonstrated by inhibition of cell rounding in Vero cells. Collectively, these findings identify RBD2 as a promising vaccine antigen targeting CDT and provide functional evidence supporting its critical role in CDT-mediated host-cell intoxication. Incorporation of RBD2 into multivalent C. difficile vaccines may broaden protection against hypervirulent, CDT-producing strains.

Animal venoms are a rich source of bioactive molecules, yet their diversity remains incompletely characterized in many species. Here we present the first long-read transcriptomic analysis of venom glands from Philippine tarantulas (Theraphosidae), a highly endemic but understudied group. Using Oxford Nanopore sequencing, we reconstructed near full-length venom gland transcriptomes across multiple species and identified extensive repertoires of toxin-encoding peptides. Venom glands were enriched in cysteine-rich inhibitor cystine knot (ICK) peptides, which dominated the toxin landscape and are known modulators of ion channels. Cross-species comparative analyses revealed a distinct transcriptional signature separating venom from non-venom tissues, driven by coordinated expression of toxin-associated and regulatory gene families. Phylogenomic reconstruction based on orthologous peptides recovered expected taxonomic relationships while revealing potential lineage-specific diversification and potential cryptic taxa. Despite a conserved core set of toxin families, substantial variation in toxin composition was observed among species, consistent with rapid evolution driven by gene duplication and functional divergence. Analysis of highly expressed ICK peptides showed a conserved cysteine framework alongside marked sequence variability in inter-cysteine regions, supporting a model in which structural stability is maintained while functional diversification proceeds. Together, these findings establish the first long-read transcriptomic resource for Philippine theraphosid spiders, reveal a conserved molecular signature underlying venom gland specialization, and provide new insights into the diversification of ICK toxin repertoires that may facilitate future evolutionary and functional studies, including the discovery and characterization of bioactive venom peptides.

Alternaria fungi produce various structurally diverse mycotoxins, several of which exhibit immunomodulatory properties. Among these, alternariol monomethyl ether (AME), alternariol (AOH), alterperylenol (ALTP), altertoxin I (ATX-I), and altersetin (AST) have been reported to suppress lipopolysaccharide (LPS)-induced inflammatory responses. However, the precise molecular mechanisms underlying these effects remain unclear. The present study aimed to elucidate how these selected Alternaria mycotoxins (0.1-50 M) target the NF-{kappa}B signaling pathway in THP-1 monocytes. Key components of the NF-{kappa}B cascade were analyzed by immunofluorescence microscopy, Western blotting and qRT-PCR. Nuclear translocation of NF-{kappa}B p65 and its phosphorylated form (p- NF-{kappa}B p65) was assessed by Western blot, while cytokine responses were determined at transcript (qRT-PCR) and protein (ELISA) levels. Moreover, in silico docking analyses were performed to investigate potential interactions of the toxins with IKK{beta}, and receptor-mediated crosstalk was studied using the glucocorticoid receptor (GR) antagonist RU486. Co-treatment with RU486 attenuated the immunosuppressive effects of 1 and 5 M AOH, indicating partial involvement of GR-dependent mechanisms. AME, AOH, ALTP, ATX-I, and AST increased total I{kappa}B levels while reducing its phosphorylated form. Additionally, AST and ALTP decreased the protein levels of Toll-like receptor 4 (TLR4), the I{kappa}B kinase (IKK) complex, NF-{kappa}B p65, and p- NF-{kappa}B p65. While AOH (5 M) and AST (25 M) reduced nuclear translocation of p65 and p-p65, ALTP (2 M) enhanced nuclear localization despite decreasing cytokine expression. Together, these findings suggest toxin-specific interference at multiple regulatory levels of NF-{kappa}B signaling and provide novel mechanistic insight into the immunomodulatory effects of Alternaria mycotoxins.

Anthelmintic drugs are used to control soil-transmitted helminths that infect a third of the worlds human population. There is increasing concern about the development of resistance to anthelmintic drugs because of the limited number of compounds available and there is an unmet need for new resistance-busting drugs. Here we describe the presence of a previously unrecognized endogenous acetylcholine analogue, {beta}-alanine betaine, which may serve as an endogenous ligand for an alternate subfamily of nicotinic receptors (DEG-3/DES-2) that could be developed as novel drug targets because their analogues are not present in their human or animal hosts. We collected peri-enteric fluid from female Ascaris suum (a model for the human parasite, Ascaris lumbricoides) and subjected it to chromatography and MS/MS to reveal signals consistent with acetylcholine, choline, and {beta}-alanine betaine but we did not recover betaine. We injected betaine into female Ascaris suum which produced no effect. However, injection of {beta}-alanine betaine, produced characteristic pretzel coiling and injection of levamisole produced a rod-like spastic paralysis. The differences between {beta}-alanine betaine and levamisole suggested that they activate different nAChRs subfamilies. PCR showed that messages of the DEG-3 subfamily of nAChR channels, which are betaine targets and were present in the intestine and body wall of A. suum. Calcium signaling experiments showed that {beta}-alanine betaine increased intracellular calcium of the intestine enterocytes and electrophysiology of the body muscle cells demonstrated that {beta}-alanine betaine produced membrane potential depolarization. In N2 elegans, application of {beta}-alanine betaine produced gradual inhibition of motility, which was reduced in acr-20, acr-23, des-2, deg-3 and lgc-41 null-mutants. These observations suggest that, in addition to acetylcholine, {beta}-alanine betaine - an anaerobic analog of betaine - may function as an endogenous ligand in anaerobic nematodes such as A. suum. An expanded repertoire of nicotinic acetylcholine receptor subfamilies in nematodes relative to mammals may reflect a corresponding need for diversification of cholinergic endogenous ligands in these organisms. This repertoire could allow their simpler neuronal system to perform more complex controls and be exploited for development of different and novel subfamily selective cholinergic anthelmintics.

Tenuazonic acid (TeA) is one of the most frequently detected Alternaria mycotoxins in contaminated food. Despite its frequent occurrence, its immunomodulatory effects remain insufficiently characterized. Therefore, the present study investigated the impact of TeA on inflammatory signaling and cytokine regulation in monocytes and intestinal epithelial cell (IEC) models. NF-{kappa}B activity was assessed using a reporter gene assay in THP1-Lucia monocytes, while cytokine mRNA expression and protein secretion were quantified in Caco-2 and HCEC-1CT cells by qRT-PCR and ELISA, respectively. In THP-1 monocytes, TeA significantly suppressed lipopolysaccharide (LPS)-induced NF-{kappa}B activation in a concentration-dependent manner starting at 25 M, while cytotoxicity occurred only at concentrations [≥]100 M. In HCEC-1CT and differentiated Caco-2 cells, TeA increased IL-6, IL-8, and TNF- mRNA levels at non-cytotoxic concentrations ([≥]10 M). In Caco-2 cells, these transcriptional changes were accompanied by increased cytokine secretion, whereas HCEC-1CT cells showed only partial effects on the protein level after short-term exposure. Following prolonged incubation, TNF- secretion was increased and IL-6 and IL-8 secretion were slightly reduced. IL-10 remained unaffected under all conditions. Overall, TeA exerted cell type-dependent immunomodulatory effects characterized by immunoinhibitory activity in monocytes and pro-inflammatory responses in IECs, highlighting the complex immunotoxic potential of this Alternaria mycotoxin.

Pore forming toxins (PFTs) are cytotoxins secreted in water-soluble form by pathogenic bacteria. They have the ability to form pores in the membrane of host cells, ultimately leading to cell death by lytic activity. Staphylococcus aureus produces a variety of bi-component PFTs, the leukocidins, which target and lyse particular leukocytes, erythrocytes and endothelial cells through specific interactions with membrane receptors. Most of these receptors belong to the family of complement or chemokine receptors that are G protein-coupled receptors (GPCRs). Gamma-hemolysins (Hlgs) are the major leukocidins secreted by S. aureus, and form receptor-dependent hetero-octameric pores through mechanisms that are not fully elucidated. Studying these molecular mechanisms is technically challenging due to the requirement of specific receptors in a lipid bilayer environment. In the present article, we developed a simple and highly sensitive method allowing cell surface expression of a large diversity of target receptors and recording in real-time, currents generated by neo-formed pores. This method is based on the heterologous expression of receptors in Xenopus oocytes and on the two-electrode voltage-clamp technique with electrophysiological robots. Using this approach, we characterized the concentration dependent-kinetics of pore formation, determined the receptor density as a limiting factor, showed specific response to non-cognate pairing of PFTs, observed cell surface binding of F subunits preceding pore formation and propose a hybrid model of subunit oligomerization. This method could be easily implemented for the in vitro characterization of various PFTs on a wide diversity of membrane receptors, to decipher early mechanisms of pore formation or to screen therapeutic agents blocking the cytotoxicity of receptor-dependent PFTs. Author SummaryStaphylococcus aureus is a bacterial species naturally present in our external flora and environment, but it is also one of the main pathogens responsible for nosocomial infections in hospital, with strains having highly problematic multi-resistance to antibiotics. S. aureus is able to secrete various virulence factors, some of which can specifically target and lyse our immune cells, making us more vulnerable to this pathogen. Thus, leukotoxins bind to receptors on the cell surface, drastically change their conformation and form cytotoxic pores in the membrane. Studying the molecular mechanisms underlying the formation of these pores is technically challenging due to their requirement for specific receptors. Here, we tested a simple electrophysiological method enabling the real-time measurement of pore formation on model cells (Xenopus oocytes), which express the receptors of interest. We were thus able to elucidate the kinetics of pore formation, the limiting role of receptors in this process, and propose a complementary model to the standard model. We also demonstrated the ability of this method to detect pore formation of non-cognate pairs of subunits and suggest further applications to characterize pore-forming properties of other toxins, to identify new target receptors, or to screen therapeutic agents inhibiting the formation of pores.

The type VII secretion system (T7SS) is a membrane-embedded protein export pathway found in mycobacteria and Gram-positive bacteria. Recently it was shown that Mycobacterium abscessus uses its ESX-4 variant of the T7SS to secrete a toxin, EatA, which targets arabinogalactan present in the mycobacterial cell envelope. Prior to its export, EatA forms a complex with a pair of small proteins from the WXG100 family, TapA1 and TapA2. Here we investigated a structural model of the EatA N-terminal domain in complex with TapA1 and TapA2 using site-directed mutagenesis and bacterial 2-hybrid assays. Our results are consistent with the three proteins forming a stacked bundle of alpha-helices. Structural modelling also predicted an interaction of the EatA-TapA1-TapA2 complex with EsxT-EsxU, a second pair of WXG100-family proteins that are likely required for the mechanistic operation of ESX-4. Whilst we could demonstrate a potential interaction between TapA2 and EsxT by bacterial 2-hybrid analysis, we were not able to purify a complex of all five proteins.

Cercarial elastase is the most abundant protease secreted by Schistosoma mansoni and plays a critical role in cercarial invasion. Although Schistosoma japonicum encodes only a single elastase, SjCE2b, its secretion by cercariae and its specific function in skin penetration have remained elusive. Here, we report the first proteomic analysis of S. japonicum cercarial excretory-secretory products (ESPs) induced by linoleic acid or mouse skin, confirming the presence of SjCE2b in both ESPs preparations. Recombinant SjCE2b expressed in Pichia pastoris was characterized as a trypsin-like serine protease whose activity is entirely abolished by the elastase inhibitor MeoSuc-AAPF-CMK. Furthermore, SjCE2b expression was detected exclusively in cercarial extracts and localized specifically to the cercarial acetabular glands and ducts. Subsequent proteomic analysis indicates that SjCE2b can degrade numerous human epidermal proteins, including ten isoforms of type I and type II keratins. In vitro digestion assays further demonstrated that SjCE2b can digest key structural components of the dermis, including elastin, collogen, and fibronectin. Additionally, the cleavage of complement component C3 and immunoglobulins (IgA and IgG) suggests that SjCE2b may facilitate immune evasion by newly transformed schistosomula. Critically, the incubation of cercariae with anti-rSjCE2b antibody reduced the worm burden by 80.85%, confirming the essential role of SjCE2b in the skin penetration of S. japonicum cercariae and highlighting it as a compelling candidate for vaccine or therapeutic development. Author SummarySchistosomiasis constitutes a major global health burden caused by parasitic flatworms of the genus Schistosoma. Proteolytic and histolytic enzymes secreted by cercarial pre- and post-acetabular glands facilitate disruption of the host skin barrier and protect the parasite from localized dermal inflammatory response. Although cercarial elastase is a well-characterized invasion enzyme in Schistosoma mansoni, its role in Schistosoma japonicum remains poorly defined; consequently, S. japonicum cercariae have been hypothesized to rely on distinct repertoire of proteolytic enzymes during skin penetration. In the present study, we showed that SjCE2b was localized to the cercarial acetabular glands and ducts, and was secreted upon stimulation with linoleic acid or mouse skin. Functionally, SjCE2b can disrupt host skin integrity by degrading epidermal and dermal components, and may promote immune evasion through cleavage of complement component and immunoglobins. Furthermore, the antibody-mediated neutralization of secreted SjCE2b significantly impaired parasite penetration by greater than 80%. Together, these findings establish SjCE2b as a critical enzyme required for S. japonicum cercariae invasion and highlight its potential as a promising target for novel therapeutic interventions.

Intestinal insect cells are integral to pharmacokinetic research, unfortunately they do not serve as cell models for more advanced studies comparable to transport studies typically conducted in mammalian models. To overcome this limitation, in this study, we developed a Caco-2 cell line that has been genetically modified to mimic insect-like characteristics, providing a robust insectified screening platform to monitor transport processes of xenobiotics. This platform consists of Wild Type (Pgpwild type) cells, an Pgp Knockout (PgpKO) line to eliminate endogenous background interference, and species-specific P-gp rescue lines. These rescue lines allow for the stable expression of human (Hs Pgp), cotton bollworm (Ha Pgp), and malaria mosquito (Ag Pgp) homologs, enabling a direct comparative analysis of efflux kinetics across different pesticide target and non-target biological systems. Functional validation using the substrate Digoxin confirmed high P-gp dependency within the platform. Methyl-parathion, an organophospate insecticide, was recognised and transported by both insect and human Pgps. This is consistent with the low mammalian selectivity of the compound. In contrast, Triflumezopyrim exhibited a high efflux ratio that remained remarkably stable even in the absence of MDR1, indicating that the uptake and pharmacokinetics of this compound are not Pgp-dependent. By successfully differentiating between transporter-specific and independent pathways these cell lines can serve as a high-fidelity screening tool for predicting novel pesticide selectivity and possibly validating the potential role of transporters in resistance. The system can be expanded and exploit also other transporters.

The excitability of afferents involved in nociceptive signaling reflects the interaction of several co-expressed membrane receptors. Current studies have shown that Toll-like receptor-4 (TLR-4) signaling can exacerbate excitation evoked by transient receptor potential vanilloid type 1 (TRPV1) activity, and this interaction plays a key role in driving and sustaining facilitated pain states. The mechanism by which this potentiated TRPV1 activity secondary to TLR-4 agonism occurs in sensory neurons remains unknown, although intracellular kinase activity is a strong candidate. To address this hypothesized linkage, neuronal cell cultures prepared from dorsal root ganglia (DRG) of male wildtype (WT) and Tlr4-/- mice were used to evaluate calcium transients of neurons after capsaicin administration in culture, pre-treated for 30 minutes with the TLR-4 agonist, lipopolysaccharide (LPS). TRPV1 protein expression at the neuron surface in cultured DRG cells with or without LPS treatment was quantified by flow cytometry assay. The roles of protein kinase A (PKA) and C were assessed using selective inhibitors (KT5720 for PKA and Chelerythrine chloride for PKC) applied to WT-DRG neurons or administered in vivo by intraplantar or intrathecal injection, prior to LPS and capsaicin administration. Behavioral effects of in vivo TRPV1 activation were assessed through paw flinch responses evoked by intraplantar capsaicin injection and by hind paw tactile thresholds measured by von Frey filaments. LPS incubation in cultured DRG neurons enhances the intensity of calcium influx following TRPV1 activation in WT but not Tlr4-/ cells. The augmented calcium influx evoked by capsaicin was prevented by the inhibition of PKA but not PKC. Similarly, mice treated with LPS in the hind paw displayed greater nociceptive responding after capsaicin and increased tactile allodynia. The facilitated component was prevented by the local pre-treatment with the PKA inhibitor. Correspondingly, lumbar spinal blockade of PKA resulted in temporary reversal of hyperalgesia induced by intrathecal LPS injection in mice. Together, these results demonstrate the relevance of TLR-4 in modulating the excitability of nociceptor signaling by regulating TRPV1, thereby influencing pain transmission through PKA signaling.

Ivermectin is an important broad-spectrum anthelmintic used to treat nematode parasites including gastro-intestinal infections of humans and animals. The mode of action for Ivermectin is understood to involve activation of inhibitory glutamate-gated chloride channels (GluCls). Ivermectin has also been reported to inhibit the release of extracellular vesicles (EVs). We found that EVs are released from the whole intestine of the gastro-intestinal parasite, Ascaris suum. Proteomic analysis identified 1,574 proteins within these intestinal EVs, including 96 nematode proteins with putative immune-associated functions based on homology to proteins involved in host immune processes and 130 proteins with predicted digestive functions. Comparative analysis following ivermectin exposure revealed 38 differentially abundant proteins that included the putative immune-related proteins: transthyretin-like proteins, a small heat-shock antigen, a phospholipase A2, and the NF-{kappa}B subunit p105. Thus, ivermectin modulated the potential immune-related cargo of intestinal EVs. The ivermectin inhibition of intestinal EV release was concentration-dependent with an IC50 of 64 nM. We also identified the expression of GluCl subunit receptor genes in the Ascaris intestine. The potent inhibitory effect of ivermectin on the release of these EVs from the nematode intestine and the expression of GluCl channel subunits sheds further light on the site and mechanisms of action of this important anthelmintic.

Background and aims Model systems for bile duct disorders are needed for testing therapeutic interventions. Current models have poor human relevance or limited potential for recreating the complex bile duct microenvironment at scale. We aimed to generate a humanized microphysiological system to model and treat cholangiopathies. Methods An in vitro bile duct was created using 3D printed microfluidic chips containing a collagen-embedded canal seeded with patient-derived primary human cholangiocytes. Barrier permeability and compound transport across the epithelium was measured, and disruption of the barrier was performed with lipopolysaccharide treatment. The duct was challenged with the known hepatotoxicant Chlorpromazine. Biliatresone was used to model biliary-atresia and treated using N-acetyl-L-cysteine. Results Cholangiocytes in the bile duct chip established a tight, polarized epithelial barrier. Verapamil and Linerixibat inhibited transport of rhodamine 123 and cholyl-lys-fluorescein respectively with 66 % (p = 0.0004) and 57 % (p = 0.03) reduction. 10 g/mL lipopolysaccharide led to a loss of epithelial barrier integrity, measured by an increase of over 1000 % in leakage of both 3 kDa (p = 0.0002) and 10 kDa dextran (p = 0.0001) along with upregulation of cytokines. Chlorpromazine displayed dose-dependent toxicity with EC50 values of 84, 140 and 96 M for three patient lines. Biliatresone induced a dose-dependent abnormal phenotype with loss of viability. The induced phenotype could be treated with N-acetyl-L-cysteine, improving viability from 23 % to 59 % (p < 0.0001) with treatment of 2 g/mL Biliatresone. Conclusions Our novel platform allows complex studies of bile duct biology, testing of off-target effects from drugs and treatment of a disease phenotype.

The eukaryotic pathogen Leishmania major causes disfiguring cutaneous lesions, whose resolution can be complicated by secondary bacterial infections. Bacteria, including Aeromonas spp., also interact with L. major promastigotes in the sandfly midgut. The mechanisms by which L. major competes with bacteria and resists their toxins are poorly defined. Prior work proposed that L. major resists the Aeromonas-produced pore-forming toxin aerolysin using an altered GPI-anchor. However, we found that L. major is sensitive to aerolysin. Here, we determined the mechanism by which L. major promastigotes are sensitive to aerolysin, using flow cytometry and biochemical approaches to analyze promastigotes genetically deficient in enzymes that produce key membrane components. The virulence factor lipophosphoglycan protected L. major from aerolysin cytotoxicity. The metalloproteinase GP63 exerted the necessary furin-like protease activity to activate aerolysin. Leishmanial GPI-anchored proteins were necessary for aerolysin heptamerization and killing of L. major promastigotes. Finally, mutation of the GPI-anchor binding domain of aerolysin crippled its cytotoxicity, consistent with its reliance on the GPI-anchor binding site to engage GPI anchors on the surface of L. major promastigotes. Taken together, we propose the L. major virulence factor lipophosphoglycan defends against pore-forming toxins made by bacterial competitors, while the GP63 metalloproteinase activates pro-aerolysin like furin. Overall, this study highlights approaches microbes use to compete with each other. Graphical AbstractAerolysin cytotoxicity depends on gp63 and LPG in Leishmania major promastigotes. (A) Wild type Leishmania major promastigotes are sensitive to aerolysin, which forms lethal heptameric pore complexes in the plasma membrane (B) L. major lpg1-- promastigotes are highly sensitive to aerolysin challenge because they lack LPG. (C) L. major gp63-- promastigotes have wild type sensitivity to aerolysin challenge but resist pro-aerolysin. (D) L. major gpi8-- knockout promastigotes are resistant to aerolysin and show no heptameric pore complexes in the plasma membrane. Created in BioRender.

Fungal surfaces must remain hydrophobic to enable growth, dispersal, and survival under fluctuating environmental conditions, yet the molecular basis of this property remains incompletely understood. Here, we identify fungisporins, fusahexins, and related cyclic non-ribosomal peptides (NRPs) as members of a conserved functional class of fungal metabolites, termed WAter Repellent Peptides (WARPs), that are required for fungal surface hydrophobicity. Across filamentous fungi, WARPs vary substantially in sequence and length but share conserved structural features, including cyclization, hydrophobic amino acid composition, and alternating D- and L-configurations, consistent with a flexible amphiphilic scaffold. Loss of WARP-producing non-ribosomal peptide synthetases results in rapid collapse of aerial hyphae upon water exposure, demonstrating that these peptides are required for maintenance of hydrophobic aerial structures. Using phage-display-derived antibodies, we localize WARPs to the hyphal surface, supporting their role as surface-associated structural components. Together, these findings identify a conserved NRPS-encoded peptide system that contributes to fungal hydrophobicity and establish WARPs as a broadly distributed class of surface-associated metabolites with structural function in filamentous fungi.

Crown-of-thorns sea star (CoTS), Acanthaster cf. solaris, outbreaks are a major cause of hard coral cover decline across the west Pacific, threatening coral reefs. Coral taxa vary in susceptibility to CoTS predation from preferred (Acropora spp.) to non-preferred (Porites spp.), yet the mechanisms underlying these differences are poorly understood. We investigated coral defenses during an ongoing CoTS outbreak in Mo'orea, French Polynesia by examining gene expression (including putative toxin genes) in healthy and actively predated colonies of a preferred (Acropora hyacinthus) and a non-preferred (Porites sp.) coral prey species. During predation, A. hyacinthus exhibited molecular signatures of cellular stress responses involving oxidative stress signalling, inflammation, and tissue proteolysis. In contrast, Porites sp. showed enrichment of genes involved in mitochondrial metabolic adjustment and aerobic metabolism, suggesting metabolic compensation to maintain cellular function. Furthermore, A. hyacinthus demonstrated a reactive defense behaviour by differentially expressing toxins (e.g., kunitz-type neurotoxins) while Porites sp. employed constitutive expression of all putative toxins regardless of active predation, suggesting a proactive defense strategy. Together, these findings suggest that preferred and non-preferred coral prey exhibit fundamentally different molecular and defensive strategies during CoTS predation, shedding light on the evolutionary arms race between corals and their predators.

Immunosuppressive drugs, which are required to maintain graft function in transplant recipients, are associated with many unavoidable side effects including posttransplant diabetes mellitus (PTDM) that involves both peripheral insulin resistance and impairment of insulin secretion. To characterize in detail the concentration-dependency of the effect of well-known immunosuppressive drugs on glucose-stimulated insulin secretion (GSIS), we performed dynamic perifusion studies with human pancreatic islets. The effect on the time-profile of GSIS has been assessed over a wide concentration range for several clinically relevant immunomodulatory therapies, including small-molecule drugs (cyclosporine, sirolimus, tacrolimus, prednisolone acetate, and loteprednol etabonate) and biologics (abatacept and anti-CD40L), plus a prospective {beta}-cell proliferation-inducing agent (harmine). While biologics showed no significant detrimental effects after one-day treatment even at relatively high concentrations (5 {micro}M), all small-molecule drugs inhibited insulin secretion in a concentration-dependent manner, although glucocorticoids showed a distinct response pattern. Calcineurin and mTOR inhibitors preserved GSIS within their therapeutic ranges but progressively distorted its time-profile at higher concentrations and completely suppressed secretion at the highest levels. Cyclosporine exhibited the least, only about 35-fold, separation between its therapeutic target (Ctarg) and half-maximal GSIS inhibitory (IC50) concentrations. Glucocorticoids did not alter the shape of the time-profile but inhibited overall insulin secretion even at therapeutic levels. Their inhibitory effect only increased slowly with concentration and did not follow a classic sigmoid pattern that has unity Hill slope. These findings establish quantitative benchmarks for immunosuppressant-induced {beta}-cell toxicity and provide a framework for optimizing immunosuppressive regimens to reduce the risk of PTDM.

Magnetic treatment in tomato seeds (Solanum lycopersicum L.) has been studied as a biotechnological technique to induce a reduction in germination times and enhance plant development. However, the modified cellular mechanisms involved in the reduction of germination times or the improvement of development parameters are not yet clearly established. To explore a possible altered cellular mechanism, the effect of homogeneous static magnetic fields on the structure of the cyclic nucleotide-gated channel 6 (CNGC6), the modification in the organization of POPC lipids in the plasma membrane, and changes in calcium ion mobility were evaluated. For this purpose, coarse-grained molecular dynamics simulations were performed using the Martini 3 model in GROMACS, applying five different magnetic flux densities (0.000, 0.001, 0.010, 0.100, 1.000, and 10.000) T over 1 000 ns. The results showed an anisotropic effect in the longitudinal direction of the protein, which generated heterogeneous behavior among the chains of the homotetramer; this altered the conformation of the CNGC6 channel and modified the pore bottleneck. In contrast, no significant changes were observed in the conformational order of the POPC phospholipid chains. As a preliminary, single-replicate exploratory study, these results suggest that homogeneous static magnetic fields may induce specific structural modifications in the CNGC6 ion channel of Solanum lycopersicum L. without compromising the integrity of the lipid bilayer or the dynamics of ion transport within the analyzed timescale; these preliminary findings provide a molecular-level structural basis for future experimental and computational investigations of magnetic field effects on plant cyclic nucleotide-gated channels.

Yeast infections are becoming an increasing public health concern, mainly due to the spread of opportunistic species and the emergence of strains resistant to commonly used antifungal drugs. Marine resources are a promising source of bioactive compounds, including polysaccharides and other biopolymers with potential antifungal applications. In this study, a sulfate-containing polysaccharide-rich extract was obtained from the red alga Jania adhaerens and chemically characterized. Its antifungal activity was compared with that of a commercial chitosan formulation against clinically relevant yeasts, including species of Candida, Cryptococcus, 'Clavispora, Naganishia and Trichosporon. Growth kinetics were monitored in liquid medium over 24 h, and antifungal activity was evaluated through growth rate analysis, growth inhibition at 20 h and susceptibility clustering. The polysaccharide extract showed moderate but consistent growth inhibition, with the strongest effects observed at 5 mg mL-1. Maximum growth inhibition reached 60.9% in Cryptococcus deuterogattii and 59.8% in Candida albicans, although no complete inhibition was observed within the tested concentration range. In contrast, chitosan showed a stronger antifungal effect, with minimal inhibitory concentration (MIC) values between 10 and 20 {micro}g mL-1 in several species and maximum inhibition values above 80% in the most susceptible yeasts. However, C. albicans showed marked resistance to chitosan, with inhibition below 12%. K-means clustering confirmed distinct susceptibility profiles between treatments, supporting a species-dependent response. Overall, these results highlight marine-derived biopolymers as promising antifungal candidates and show that chitosan and algal sulphated polysaccharides produce distinct, species-dependent antifungal profiles.

The phenotypic plasticity, slow replication, and complex, hydrophobic cell envelope of Mycobacterium tuberculosis contribute to its successful survival as a pathogen and its drug tolerance. Consequently, the global threat of multidrug-resistant Tuberculosis (MDR-TB), coupled with lengthy and highly toxic treatment regimens, necessitates the development of innovative treatment solutions. Mycobacteriophages are natural viruses of mycobacteria that typically encode two endolysins, which cooperatively facilitate host cell lysis at the end of the lytic life cycle: LysA, a peptidoglycan hydrolase, and LysB, a lipolytic enzyme, targeting the mycolylarabinogalactan-peptidoglycan complex. Their precise and efficient lytic activity, along with their low propensity to induce resistance, make them, particularly LysBs, promising candidates for new treatment solutions. In this study, we report MTB-LysB1, a novel LysB enzyme from an F1 sub-cluster mycobacteriophage isolated from our laboratory collection. While studying its structural features by comparing the modelled structure with representative mycobacteriophage LysB homologues, we found that the /{beta}-hydrolase fold and key motifs are conserved. Also, we identified putative membrane-interaction motifs that may play a role in LysB1s cell permeation. Significantly, we found MTB-LysB1 to be active against both drug-susceptible and multidrug-resistant (MDR) M. tuberculosis strains at nanomolar concentrations, comparable to the well-characterised D29 LysB reference enzyme. Beyond its standalone activity, MTB-LysB1 exhibits an additive effect when combined with the TB drugs rifampicin and moxifloxacin, and co-administration reduces the drugs minimum inhibitory concentrations (MICs), which holds clinical significance. By structurally damaging the mycobacterial cell wall, the enzyme appears to act as a permeability enhancer for the chemotherapeutic drugs, thereby improving antibiotic efficacy. Collectively, our findings position the enzyme not only as a novel antimycobacterial agent but also provide a structural framework for its rational engineering as a promising next-generation adjunct to TB drug regimens. HighlightsO_LIA novel F1 sub-cluster phage-derived LysB is discovered and characterised using integrated computational, biochemical and microbiological methods. C_LIO_LIAlphaFold2 modelling, molecular dynamics simulations and comparative structural analyses revealed an /{beta}-hydrolase fold with conserved catalytic and membrane-interaction features. C_LIO_LIThe enzyme exhibited high esterase activity, thermal stability and potent lytic activity against Mycobacterium tuberculosis. C_LIO_LIAn additive effect with TB drugs rifampicin and moxifloxacin highlights MTB-LysB1s potential as an adjunct therapeutic. C_LI