Moscow State University Lomonosov

The natural phytoestrogen ferutinin acts as a divalent cation-selective ionophore, promoting the opening of Ca²⁺-activated permeability transition pore (PTP) in mitochondria. Here, we found that Mg²⁺ cations, known to suppress PTP, markedly augmented the ferutinin-induced permeabilization of rat liver mitochondria. To uncover the permeabilization mechanism, we measured calcein flow from large (LUV) and giant (GUV) unilamellar vesicles. In both cases, the ferutinin-induced calcein efflux was significantly enhanced in the presence of Ca²⁺ or Mg²⁺. Calcein influx into GUV stopped within 15-min incubation with ferutinin and Ca²⁺. In electrophysiological experiments, ferutinin caused a smooth increase in the electrical current through planar bilayer lipid membranes (BLM) in the presence of Ca²⁺ or Mg²⁺, followed by burst of fluctuations in the current at its high level. In patch-clamp BLM experiments, we detected transient channel activity upon the addition of ferutinin together with Ca²⁺, diminishing over minutes time scale. We propose permeabilization mechanism which involves adsorption of ferutinin on lipid membranes, its dimerization upon binding Mg²⁺ or Ca²⁺, leading to mechanical stress induction, and ultimately to membrane pore formation. The mechanical stress is then gradually relieved due to translocation of ferutinin dimers and lipid molecules to the opposite lipid monolayer, resulting in pore closure.

Plerocercoids of the order Phyllobothriidea were discovered in the gastrointestinal tract of the three-spined stickleback, Gasterosteus aculeatus, and White Sea cod, Gadus morhua marisalbi, in the White Sea. Based on the 28S rDNA sequence, plerocercoids from Gasterosteus aculeatus belong to Rockacestus cf. piriei. A phylogenetic tree was reconstructed to infer their evolutionary relationships. Several aspects of larval biology were described: the prevalence and intensity of infection were quantified in host fishes; movement patterns of the scolex and body were documented in vitro. The maximum infection rate of Rockacestus cf. piriei plerocercoids in Gasterosteus aculeatus was observed in June 2021. Some seasonality of fish infection by these parasites can be linked with three-spined stickleback migration. The detailed morphology of the scolex and microtriches, as well as the ultrastructure of the tegument and excretory system, have been studied using scanning and transmission electron microscopy. Unlike other cestodes, the tegument lacks rod-shaped bodies in its distal cytoplasm and exhibits uniform microtriches, specifically capilliform filitriches. Subtegumental musculature is well developed. The excretory system comprises cyrtocytes and syncytial epithelium forming protonephridial funnels, thin tubules and canals. The cytoplasm of the canal wall contains numerous electron-dense rod-shaped bodies oriented parallel to the surface. Several specific features in the ultrastructure of the tegument and excretory epithelium of the R. cf. piriei plerocercoid have been identified, contributing to the taxonomic and functional understanding of marine cestodes.

Melittin, the principal bioactive component of bee venom, exhibits potent anticancer activity. However, its clinical application is hindered by nonspecific hemolytic toxicity. In this study, we developed a pH-responsive polymeric-peptide complex (PCM) to improve anti-tumor activity of melittin while minimizing off-target effects. PCM remained structurally stable under physiological conditions (pH 7.4) but underwent rapid disassembly in the mildly acidic tumor microenvironment (pH 6.8) to expose melittin. The exposed melittin bound to tumor cell membranes, compromised membrane integrity through transmembrane pore formation, leading to tumor cell death. This membrane disruption elicited the release of damage-associated molecular patterns, thereby activating antitumor immune responses. In a murine breast cancer model, low dose administration of PCM significantly inhibited tumor recurrence and metastasis, and generated durable antitumor immunological memory without significant side effects. The mechanistic actions and morphological effects of PCM on tumor cells were thoroughly investigated, providing important theoretical insights for the clinical translation of anticancer peptides.