Biology subjects

Trznadel, M.

Publications and source records attributed to Trznadel, M..

3 recordsLinked to original sources

bioRxiv2025

Evaluating anaesthetics for improving scientific research and welfare using larval zebrafish

Establishing anaesthesia for ensuring both animal welfare and compatibility with protocols required for different areas of scientific research is vital. Zebrafish (Danio rerio) are one of the most used animal models in research; however, little is known about the appropriateness of anaesthetic used for this species, especially for embryo-larval life stages. Using a combination of whole-brain functional imaging, quantification of cardiovascular performance, and behaviour, we explore the efficacy and tolerability of six widely used fish anaesthetics (2-phenoxyethanol, benzocaine, etomidate, MS222, isoeugenol and quinaldine sulfate) in larval zebrafish. We show that MS222 and quinaldine sulfate are the most suitable for achieving deep anaesthesia, while etomidate is better suited for studies focused on the cardiovascular system. Only quinaldine sulfate was found to be aversive. Our findings aid researchers for selecting the most suitable anaesthetic compounds and concentrations for their specific research goals, and the refinement of studies using anaesthesia in larval zebrafish.

physiology↗

bioRxiv2025

Neural and Behavioral Dynamics of Acute Fentanyl Administration and Implications for Hazard Assessment of Novel Synthetic Opioids in Larval Zebrafish

Rationale Synthetic opioids pose a significant public health risk due to their rapid synthesis and potentially lethal potency. New compounds are emerging continuously, meaning current testing platforms struggle to keep pace. Objectives Consequently, there is a critical need for simple, rapid, translatable models to provide a scalable screening platform to identify and hazard-assess emerging synthetic opioids, and test potential intervention strategies. Methods Here, we exposed 4 days post-fertilization (dpf) larval zebrafish to a range of concentrations of the prototypical class representative, fentanyl, to investigate behavioral and neural responses. Results Fentanyl caused low concentration hyperactivity, and high concentration hypolocomotion (sedation) which was reversed by the opioid antagonist naloxone. We confirmed predictive validity by replicating the behavioral responses with other class representatives (diacetylmorphine [heroin] and remifentanil). We also confirmed, pharmacologically, that low concentration hyperlocomotion was mediated by dopamine D2 receptors, replicating effects observed in mammals. Further mechanistic investigation using whole-brain in vivo imaging revealed disrupted connectivity in opioid-related circuits, such as the habenulae and dorsal thalamus, alongside novel pathways, including circuits associated with the pineal gland, torus semicircularis and eminentia granularis, potentially highlighting previously uncharacterized sensory and cerebellar neuronal networks. Conclusions These findings support the use of the larval zebrafish as a scalable model for assessment of synthetic opioids to provide novel insights into opioid-induced behaviors and mechanisms of action that may aid strategies in the growing challenge of interventive treatments for synthetic opioid intoxication. Impact StatementLarval zebrafish reveal neurobehavioral pathways affected by synthetic opioids, offering a valuable tool for rapid hazard assessment.

animal behavior and cognition↗

bioRxiv2025

Fireworms (Hermodice carunculata) are a reservoir and potential vector for coral-infecting apicomplexans

Corals (Cnidaria; Anthozoa) play critical roles as habitat-forming species with a wide range, from warm shallow-water tropical coral reefs to cold-water ecosystems [1-3]. They also represent a complex ecosystem as intricate holobionts made up of microbes from all domains of the Tree of Life, that can play significant roles in host health and fitness [4]. The corallicolids are a clade of apicomplexans that infect a wide variety of anthozoans across the world, and can influence the thermal tolerance of habitat-forming corals [1, 5]. Despite their potentially important impacts on reef ecosystems, much of the basic biology and ecology of corallicolids remains unclear. Apicomplexans often have a closed life cycle, with minimal environmental exposure, and sometimes multiple hosts. Corallicolids have only been documented in anthozoan hosts, with no known secondary/reservoir hosts or vectors [6]. Here, we show that abundant corallicolid sequences are recovered from bearded fireworms (Hermodice carunculata) in tropical reef habitats off Curacao, and that they are distinct from corallicolids infecting the corals on which the fireworms were feeding at the time of their collection. The data are consistent with an active infection of fireworms, as opposed to corallicolids being a byproduct of feeding on infected corals, and we suggest that H. carunculata is potentially a vector moving corallicolids among coral hosts through its faeces. These findings not only expand our understanding of the ecological interactions within coral reef ecosystems but also highlight the potential role of host-associated parasites in shaping the resilience of reef habitats.

microbiology↗