Zsolt Pirger

Glyphosate is one of the most widely used herbicides globally and is frequently detected in surface waters in multiple regions. Despite its toxicological relevance and potential ecological and human health implications, its use was recently renewed in the EU until 2033. A growing body of literature has showed that glyphosate can cause adverse effects in mollusks, but previous studies have focused primarily on survival, reproduction, genotoxicity, and certain cellular biomarkers, leaving its effects on molluscan behavior and embryonic development largely unknown. Here, we investigated the developmental, behavioral, and biochemical consequences of chronic glyphosate exposure on embryos of the widely used molluscan model, the great pond snail (Lymnaea stagnalis). Embryos were exposed from the single-cell stage to hatching to environmentally relevant concentrations of glyphosate (25, 100, and 500 µg L-1). All applied concentrations transiently delayed hatching without causing morphological abnormalities. Moreover, the highest concentration transiently increased heart rate, locomotion, and feeding, indicating elevated metabolic requirements. Biochemical analyses in hatched embryos demonstrated that all exposure concentrations significantly reduced vitellogenin content and lipid peroxidation, whereas a significant increase in catalase and LDH was observed only at the highest concentration, suggesting altered energy allocation and oxidative stress. Histochemical staining confirmed increased LDH activity, revealing tissue-specific metabolic activity, while no histological alterations were observed in hatched embryos. Collectively, our findings reveal previously unrecognized sublethal effects of glyphosate on molluscan embryos, highlighting that this compound can disrupt growth, energy metabolism, and cellular homeostasis in Lymnaea embryos with potential consequences for post-hatching performance, resilience, and long-term fitness.

Tourism-related activities are increasingly recognized as sources of pharmaceutically active compounds (PhACs) in aquatic environments; however, the contribution of spa tourism and associated pathways remains poorly quantified. This study investigated the occurrence, spatiotemporal variability, and environmental risk of caffeine (CAF), carbamazepine (CBZ), and diclofenac (DCF) in the Zala River catchment (Hungary), which is strongly influenced by spa and medical tourism. A multi-evidence approach was applied, combining multi-year monitoring data (2018, 2024, and 2025), questionnaire-based information on pharmaceutical usage, and a multiparametric mass-balance model. The results revealed pronounced spatial variability linked to spa-impacted river sections, with DCF consistently dominating ecological risk based on both PNEC- and EQS-based assessments. DCF concentrations frequently exceeded risk thresholds and showed significant correlations with the number of medical treatments at selected sites. Questionnaire data indicated that approximately 30% of visitors used DCF-containing medications, supporting the interpretation of bathing-related release pathways. Mass-balance modelling further demonstrated that observed DCF concentrations in thermal waters can be largely explained by direct inputs from bathers, particularly via topical application, highlighting a mechanistic link between human behaviour and environmental contamination. Overall, the findings demonstrate that spa tourism can act as a significant and previously underappreciated source of pharmaceuticals in surface waters. The integration of monitoring data, behavioural information, and mechanistic modelling provides a transferable framework for identifying and characterizing tourism-related sources and pathways in aquatic environments.

Segment regeneration in earthworms is a remarkable example of postembryonic morphogenesis, yet its fidelity and cellular mechanisms remain incompletely understood. The present study investigated posterior segment regeneration in adult specimens of the earthworm model Eisenia andrei from wound closure to the 5th postoperative week using anatomical, histological, and ultrastructural approaches. Rapid wound closure occurred through fusion of the cut edges of the body wall and midgut without direct involvement of coelomocytes. The regeneration blastema consisted of dedifferentiated epithelial and muscle cells, innervated by fibers from the last intact ventral nerve cord ganglion. Coelomocytes accumulated in the last intact segments and were primarily involved in debris clearance. Notably, early regenerating tissues lacked collagen fibers, which appeared only after the third postoperative week and remained sparse until the fifth week, whereas original segments exhibited intense, region-specific collagen deposition. Transmission electron microscopy revealed characteristic cytological changes in distinct stages of body wall regeneration, including muscle dedifferentiation and the emergence of collagen-producing fibroblasts. These findings indicate that early cell migration, proliferation, and orientation in the blastema proceed independently of collagen and that collagen functions as a delayed structural scaffold, supporting tissue integrity without impeding regeneration. Importantly, no scar formation was observed between old and new tissues, resembling scarless fetal wound healing. Overall, we clarified previously controversial cellular mechanisms and propose a new, comprehensive model for the early stages of segment regeneration. Our results highlight that coordinated dedifferentiation, spatiotemporal extracellular remodeling, and delayed collagen deposition underlie effective, scar-free regeneration in earthworms, offering insights into conserved mechanisms of regenerative repair across metazoans and potential strategies for enhancing tissue regeneration in mammals.

This work demonstrates the potential of polydimethylsiloxane sponges for removing organic UV filter compounds such as octinoxate from aqueous solutions. The sponges were fabricated using simple templates made of hydrophilic fused or pressed particles (sugar or NaCl salt) with an approximate particle size of 0.4 mm. Among the prepared sponges, those templated with sugar cubes or coarse salt exhibited the highest adsorption capacity, effectively adsorbing up to 0.6% of their own mass in octinoxate. The PDMS sponges were fully regenerable, allowing for the complete removal of octinoxate without any detectable changes in their adsorption properties or dry weight. Due to their simple fabrication, ease of handling, ability to float, and reusability, PDMS sponges present an environmentally friendly and low-maintenance alternative to conventional filtration systems for the removal of octinoxate and potentially other UV filter compounds from environmental surface waters and recreational water bodies.

Anxiety, a behavioral consequence of stress, has been characterized in humans and some vertebrates but remains largely unexplored in invertebrates. Here, we demonstrate that after being exposed to fish water, which simulates the presence of predators, pond snails (Lymnaea stagnalis) exhibit a series of sustained fear responses. These include increased aerial respiration, changes in righting behavior, and reduced escape responses. Notably, these behaviors persist even after the stressor (fish water) is removed, indicating that they likely represent an anxiety-like state rather than a simple conditioned reflex. Additionally, exposure to fish water enhances long-term memory formation for the operant conditioning of aerial respiration, suggesting that the predator scent potentially induces a state of heightened alertness, which enhances memory consolidation processes. Furthermore, when snails experience fish water alongside an appetitive stimulus (carrot), they form configural learning—a higher form of learning – where the appetitive stimulus now triggers a fear response instead of eliciting feeding. Importantly, the anxiolytic drug alprazolam prevents these anxiety-like responses. Through dose-response experiments, we found that alprazolam at a concentration of 0.1 µM for 15 min effectively counteracts predator-induced anxiety without causing sedation. This treatment also prevents the effects of predator cues on learning and memory. However, consistent with data from vertebrates - alprazolam induces anterograde amnesia, impairing the formation of new memories for up to 3 h after treatment, though it does not cause long-term memory deficits. Overall, this is the first study showing that a molluscan model organism exhibits anxiety-like behaviors similar to those seen in vertebrates, and these behaviors can be mitigated by an anti-anxiety drug. This suggests that fundamental anxiety mechanisms are evolutionarily conserved across species. By using this simple invertebrate model, our research offers new insights into the biological basis of anxiety and sets the stage for future pharmacological studies.

The concentration of microplastics (MPs) in two important Hungarian freshwater habitats was determined in the size range of 50 μm–1 mm. Lake Balaton (LB) is the largest shallow lake in Central Europe, with a significant role in recreation and tourism. Its main inflow, the Zala River, enters the lake through an artificially constructed wetland, the Kis-Balaton Water Protection System and its catchment area (KB), which helps preserve the water quality of the lake. From these two areas, 15 samples were taken with an in situ filtration sampling method. After preparation, the samples were analyzed automatically by FT-IR microscopy. All samples, from both areas, contained MPs; the dominant microplastic (MP) shape was the fragment, while the most frequently polymer types were polyethylene, polypropylene and alkyd. Small MPs were dominant in both areas; around 90% of the MPs were smaller than 500 μm. On average, LB contained more MPs (21.0 ± 12.5 MPs/m³) compared to the KB, which presented an average concentration of MPs of 7.8 ± 5.9 MPs/m³. In the examined areas, two potential MP sources were determined, i.e., treated wastewater and road traffic. The importance of tourism should also be further investigated.

Members of the genus Klebsormidium are ubiquitously distributed over the Earth and are among the major biological soil crust (BSC) forming microalgae. Their representatives can be found in terrestrial, aquatic, polar, desert regions and have been investigated so far from various aspects. However, the available information about Klebsormidium isolates from lamp-flora is very limited. In our work, we examined a Klebsormidium strain isolated from a Hungarian cave. The temperature optimum of its photosynthetic performance was tested by oxygen yield measurements and pulse-amplitude-modulated fluorescence, which were completed by determination of specific growth rates at different temperatures, from 10 to 40 °C. In addition, we also evaluated the brassinosteroid (BR) content of these cultures. Our results indicated that the studied microalga is capable of growing from 10 to 40 °C, with a 20–25 °C temperature optimum; these findings were in accordance with the observed hormone levels. Regarding photosynthetic performance, the oxygen yield and chlorophyll fluorescence measurements showed maxima at 30–40 °C and 35–40 °C, respectively. Moreover, the examined Klebsormidium strain demonstrates traits associated with cave adaptation, i.e., by high light utilisation factor (α) and diminished light adaptation parameter (I_k) values.