Toxins最新文献

Bacteria use cholesterol-dependent cytolysins (CDCs) to damage eukaryotes. While well-studied in mammals, the mechanisms by which CDCs bind to and kill protozoans remain unclear. CDCs bind to the human pathogen Leishmania major but only kill in the absence of sphingolipids. The contribution of other leishmanial membrane components to CDC binding and cytotoxicity remains unknown. Here, we used genetic knockouts and inhibitors to determine the contribution of key membrane components to CDC binding and killing in L. major. We analyzed toxin binding and killing using flow cytometry and Western blotting. Loss of the virulence factor GP63 enhanced toxicity of perfringolysin O but not streptolysin O. Plasmenylethanolamine and lipophosphoglycan had minimal contributions to CDC binding and cytotoxicity. Removal of sterols protected cells from CDCs yet failed to reduce binding. We used CDCs defective in engaging glycans or cholesterol to confirm that CDCs deficient in sterol binding, but not glycan binding, could bind to L. major. Thus, in non-mammalian systems, CDCs may rely on glycans for binding, while using sterols for pore formation. This suggests that CDCs may not be sterol-specific probes in some non-mammalian systems. We conclude that early-branching eukaryotes use distinct mechanisms from mammals to limit CDC pore formation and killing.

Ergot alkaloids derived from lysergic acid have impacted humankind significantly as toxins in agriculture and as the foundations of several pharmaceuticals. Few fungi capable of producing lysergic acid derivatives have been found outside the family Clavicipitaceae. Based on its phylogenetic placement, we hypothesized the recently described fungus Aspergillus aspearensis (Aspergillaceae) would synthesize lysergic acid amides. Cultures of A. aspearensis produced abundant lysergic acid α-hydroxyethylamide (LAH) and lesser amounts of other lysergic acid derivatives. Conidia contained high concentrations of ergot alkaloids, whereas sclerotia contained significantly less. Approximately half of the ergot alkaloids produced were secreted into the culture medium. When spores of A. aspearensis were injected into larvae of the model insect Galleria mellonella, larvae died at a significantly faster rate than control larvae. The fungus produced ergot alkaloids during insect pathogenesis and later produced conidia and sclerotia on cadavers, indicating it can complete its life cycle in an insect. The genome of A. aspearensis contained two complete ergot alkaloid synthesis gene clusters, similar to those of A. leporis; however, unlike its sister species, none of the ergot cluster genes were pseudogenized. Aspergillus aspearensis is a newly discovered source of ergot alkaloids and may be useful for studying and producing these important chemicals.

Patulin (PAT) is a fatal mycotoxin that exerts serious threats to human and animal health. Biodegradation of PAT is considered to be one of the promising ways for controlling its contamination. In this study, Lactiplantibacillus plantarum 6076 (LP 6076) with reliable removal efficiency on PAT was screened out from three lactic acid bacteria (LAB) strains. It was found that the PAT was eliminated through degradation by LP 6076, and the intracellular proteins played a crucial role in PAT degradation with the induction of PAT. The proteomic analysis showed that the response of LP 6076 to PAT was by a concerted effort to repair DNA damage, in parallel to adaptive changes in cell wall biosynthesis and central metabolism. Eleven differentially expressed proteins with high fold changes were picked out and identified as PAT degradation candidate enzymes. The 3D structures of the candidate enzymes were predicted, and molecular docking between the enzymes and PAT was performed. Five enzymes, including Acetoin utilization AcuB protein (AU), GHKL domain-containing protein (GHLK), Dihydroneopterin aldolase (DA), YdeI/OmpD-associated family protein (YDEL), and Transcription regulator protein (TR), could dock with PAT with lower affinity and shorter distance. Through molecular docking analysis, DA was ultimately identified as a potential key degrading enzyme. The choice of DA was substantiated by its superior combination of strong binding affinity and a productive binding pose with PAT. VAL84 and GLN51 residues of DA were likely the active sites, forming four hydrogen bonds with PAT. Our study could accelerate the commercial application of biodegradation toward PAT decontamination.

Cell-based potency assays (CBPAs) are required for the potency testing and commercial release of botulinum neurotoxin (BoNT)-based drug products. These CBPAs must account for the toxin's biological activities while meeting regulatory guidelines for precision and accuracy. Here, studies describe the characterization and qualification of the BoSapient CBPA and demonstrate that it is fit for use as a relative potency assay for BoNT/A-containing samples. The CBPA is operated in a 96-well plate format and relies upon the fluorescence emissions of a reporter that directly responds to BoNT/A activity. The BoSapient cell line expresses the BoNT/A-receptors SV2 and complex gangliosides, is responsive only to intact BoNT/A, and can robustly detect picomolar and sub-picomolar BoNT/A quantities, making the CBPA appropriate for quantifying BoNT/A-based drug products. The cell line was passaged 30 times without significant loss of reporter expression or BoNT/A sensitivity. Manual and semi-automated CBPA methods were developed and qualified according to regulatory guidelines and shown to have low bias (<4% from expected) and high precision (standard deviation < 8) across all test concentrations. Furthermore, the semi-automated method using the CBPA is demonstrated to improve intermediate precision by 39% compared to the manual method, while reducing operator dependency during method execution.

Boy et al [...].

Plasticity is fundamental to the development, strengthening, and maintenance of healthy synaptic connections and recovery from injury in both the central and peripheral nervous systems. Yet, the processes involved are poorly understood. Herein, using a combination of patch-clamp electrophysiology and immuno-fluorescence confocal microscopy in adult mice, it is shown that blockade of synaptic transmission at submandibular ganglion junctions exposed to botulinum neurotoxin type A was accompanied by a rapid and striking decline in the abundance of synaptic vesicle markers-SV2, vesicle-associated membrane protein 2, and vesicular acetylcholine transporter-plus SNAP-25 (cleaved and intact) and postsynaptic α7 nicotinic acetylcholine receptors. Such alterations by the neurotoxin of parasympathetic synapses contrast starkly with the stability of postsynaptic proteins at nearby skeletal neuromuscular junctions. Both neurotransmission and the expression of SV2 and α7 nicotinic acetylcholine receptors remained depressed for 4 weeks, with full recovery of synaptic function delayed for more than 8 weeks. These novel findings may explain the relatively slow recovery of autonomic function after botulism or following therapeutic injections to alleviate hypersecretory disorders.

This study was focused on the assessment of fungal occurrence, mycotoxin dynamics, aflatoxin carry-over, and associated biochemical responses in dairy cattle. Moisture emerged as the dominant factor for fungal communities, promoting the co-proliferation of fungal genera adapted to high water activity conditions (a_w > 0.90) and antagonism against xerotolerant and xerophilic species. Aspergillus spp. dominated dry substrates (a_w < 0.75), Fusarium spp. showed strong positive associations with high-moisture matrices (a_w > 0.90), and Penicillium spp. exhibited intermediate, substrate-dependent behavior. Mycotoxin levels fluctuated non-linearly, independently of fungal counts: ochratoxin A (OTA) concentrations in corn silage increased from approximately 12 μg/kg at the onset of the ensiling period to >240 μg/kg at silo opening, indicating dynamic mycotoxin accumulation during storage, while zearalenone (ZEA) oscillated from 40 to 170 µg/kg. Despite the variation in total aflatoxins (AFLA-T) across feed matrices, aflatoxin M1 (AFM1) in milk remained low (0.0020-0.0093 μg/kg), confirming limited carry-over. Serum biochemical parameters-alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), total bilirubin (BIL-T), total protein (PROT-T)-remained within physiological limits, yet multivariate analyses revealed metabolic modulation linked to aflatoxin exposure. AFM1 explained >7% of the variance in serum biochemical profiles according to PERMANOVA (p = 0.002), showed significant MANOVA effect (Pillai = 0.198), and displayed a significant canonical association (p < 10^-13). Linear discriminant analysis further separated Normal vs. Borderline hepatic profiles, indicating subclinical physiological adaptation to chronic low-dose exposure.

Aflatoxin B1 (AFB1), deoxynivalenol (DON), and ochratoxin A (OTA) are common mycotoxins that frequently co-occur in cereals and pose potential risks to animal and human health. This study investigated the cytotoxic effects of AFB1, DON, and OTA, individually and in binary and ternary combinations, in four human-derived cell lines representing major target organs (Caco-2, HepG2, HK-2, and SK-N-SH). Individual toxin exposure revealed cell type-dependent sensitivity, with DON generally exhibiting the strongest cytostatic effect. Combined exposure analysis showed distinct interaction patterns across cell models, including antagonistic effects of AFB1 + OTA in most cell lines, dose-dependent interactions of DON + OTA, and low-dose synergistic effects in specific combinations. Overall, the results demonstrate that mycotoxin interactions are highly dependent on dose and target cell type, and that low-dose co-contamination may enhance toxicological risks, underscoring the importance of considering combined mycotoxin exposure in health risk assessment.

In the past few years, several mushroom poisoning incidents caused by Omphalotus species have occurred in China. In addition to O. guepiniformis and O. olearius, a new white Omphalotus species, O. yunnanensis, was discovered in Southwestern and Southern China based on morphological, molecular and toxin-detection evidence. Omphalotus yunnanensis is characterized by its small, cream to white basidiomata with a hygrophanous pileal surface, non-bioluminescent lamellae, broadly ellipsoid to subglobose basidiospores (8-12.5 × 7-10 μm), fusoid to ventricose cheilocystidia with occasional apical outgrowths, cream to white pileipellis composed of thick-walled, subsoil to solid hyphae, clavate, and fusoid to ventricose caulocystidia with occasional apical outgrowths. The species has been discovered in tropical to subtropical areas in Southwestern and Southern China. Phylogenetic analyses based on ITS and nrLSU showed that the new species clustered with the Australasian species O. nidiformis, but can be easily distinguished by its smaller, white to cream pileus, non-bioluminescent lamellae, larger basidiospores and growing on Fagaceae species. Illudin S was detected in this new species using UPLC-MS/MS, at 6.98 to 86.1 mg/kg of the content (dry weight), while no illudin M was detected.

This study investigated the effects of chronic MC-LR exposure (0 μg/L [Control], 1 μg/L [M1], 3 μg/L [M3], 10 μg/L [M10], and 30 μg/L [M30]) on the muscle nutrient composition, meat quality, and muscle proteomic profile of Nile tilapia (Oreochromis niloticus). In the high-dose group (M30), MC-LR exposure compromised the muscle antioxidant status of Nile tilapia, resulting in reduced meat quality, as evidenced by decreased pH value and water-holding capacity, elevated lipid/protein oxidation, and altered texture parameters (shear force and fragmentation index). Proteomic analysis further revealed a downregulation of proteins associated with ribosomes, suggesting an impairment of muscle protein synthesis in the M30 group. Moreover, despite chronic exposure, only low levels of MC-LR accumulated in the muscle tissue, indicating a negligible health risk to consumers. Collectively, these findings offered valuable insights into the impact of environmental MC-LR contamination on fish muscle quality and nutritional value.