Biology subjects

Courtney, A.

Publications and source records attributed to Courtney, A..

6 recordsLinked to original sources

bioRxiv2026

Protocol for calcium imaging of acute brain slices from Octopus vulgaris hatchlings during application of neurotransmitters

Octopus vulgaris and other cephalopods are of increasing interest as neurobiological model organisms. This protocol describes a method to record calcium activity from individual cells in acute brain slices from Octopus vulgaris hatchlings during exogenous application of neurotransmitters. Using this protocol, we characterized single-cell responses to specific neurotransmitters in the optic lobes, which process visual information. The approach is readily adaptable to other cephalopods and small invertebrate species. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=146 HEIGHT=200 SRC="FIGDIR/small/711860v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1a3da0forg.highwire.dtl.DTLVardef@412424org.highwire.dtl.DTLVardef@abda7eorg.highwire.dtl.DTLVardef@958ebf_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Neurons, Muscles, and Venom: Identifying Drivers of Cephalopod Predation

Venom plays a central role in the predatory ecology of coleoid cephalopods (octopuses, squids, and cuttlefish), yet the mechanisms governing venom release from the posterior salivary gland (PSG) are unknown. Using a multimodal approach combining X-ray micro-histotomography, histological stainings, in situ hybridization, comparative phylogenetics, and ex vivo imaging across multiple coleoid species, we characterize the structural and neuronal regulatory organization of the PSG. We verified that the gland comprises two distinct tubular systems: secretory tubules specialized for venom production and smooth-striated tubules positioned to facilitate venom transport toward the beak for injection into its prey. Molecular localization of filamentous and -actin confirms a circular smooth muscle layer surrounding the tubules. Mapping of six neuronal markers, including neurofilament (NF-H), synapsin, and muscle-type nicotinic acetylcholine receptors, reveals dense and stereotyped neural innervation closely associated with the muscular compartments. Comparative phylogenetic analyses of cys-loop ligand-gated ion channel sequences indicate a predominancy of excitatory acetylcholine- and dopamine-gated receptors in coleoid venom glands, implicating potential molecular agents involved in neural control of venom release. Consistent with neural regulation, ex vivo stimulation of the PSG elicits calcium signaling throughout the gland. Together, our results reveal a conserved venom gland structure among octopuses, squids, and cuttlefish, with a spatially distinct neuromuscular tissue organization indicating venom production and release sites modulated by a network of neuronal agents. This work provides a mechanistic framework into venom gland organization and molecular regulation of venom release in one of the oldest venomous lineages.

neuroscience↗

bioRxiv2025

Novel dopaminergic neurotransmission in the Octopus visual system

Octopus vulgaris, the common octopus, has a complex brain that evolved independently from that of vertebrates, raising the possibility that it may be built using novel circuit motifs or non-canonical neurochemistry. Through systematic characterization of octopus ligand-gated ion channel genes, we identified novel ionotropic receptors for two neurotransmitters, dopamine and acetylcholine, that play key roles in visual circuits. One of these, DopC1, encodes a dopamine-gated cation channel expressed in deeper layers of the optic lobe (inner granular layer and medulla). A second, AChRB1, encodes an acetylcholine-gated anion channel expressed in photoreceptors and dopaminergic outer granular layer neurons. Dopamine drives excitation, particularly in deeper, DopC1 enriched layers, and thereby may play an important role in feed-forward excitation, whereas acetylcholine evokes inhibition, possibly mediating negative feedback from deeper layers. The octopus visual system thus shows fundamental differences in both neurochemistry and wiring compared to mammals, implying distinct mechanisms of visual information processing.

neuroscience↗

bioRxiv2020

Characterisation of Geometric Variance in the Epithelial Nerve Net of the Ctenophore Pleurobrachia pileus

Neuroscience currently lacks a diverse repertoire of model organisms, resulting in an incomplete understanding of what principles of neural function generalise and what are species-specific. Ctenophores display many neurobiological and experimental features which make them a promising candidate to fill this gap. They possess a nerve net distributed across their outer body surface, just beneath the epithelial layer. There is a long-held assumption that nerve nets are simple and random while lacking distinct organisational principles. We want to challenge this assumption and determine how stereotyped the structure of this network really is. We validated an approach to estimate body surface area in Pleurobrachia pileus using custom Optical Projection Tomography and Light Sheet Morphometry imaging systems. We used an antibody against tyrosylated -tubulin to visualise the nerve net in situ. We used an automated segmentation approach to extract the morphological features of the nerve net. We characterised organisational rules of the epithelial nerve net in P. pileus in animals of different sizes and at different regions of the body. We found that specific morphological features within the nerve net are largely un-changed during growth. These properties must be essential to the functionality of the nervous system and therefore are maintained during a change in body size. We have also established the principles of organisation of the network and showed that some of the geometric properties are variable across different parts of the body. This suggests that there may be different functions occurring in regions with different structural characteristics. This is the most comprehensive structural description of a nerve net to date. This study also demonstrates the amenability of the ctenophore P. pileus for whole organism network analysis and shows their promise as a model organism for neuroscience, which may provide insights into the foundational principles of nervous systems.

neuroscience↗

bioRxiv2020

Characterising the Behaviour of the Ctenophore Pleurobrachia pileus in a Laboratory Aquaculture System

Neurobiological research focuses on a small number of model organisms, broadening the pool of animals used in research may lead to important insights into the evolution of nervous systems. The ctenophore is emerging as a promising model, but we are currently lacking an understanding into the relationship between behaviour and environment which is in part due to a lack of a standardised long-term laboratory husbandry system. We established a collection and husbandry system for wild caught Pleurobrachia pileus. We examined the behavioural profile of the animals over time in this controlled environment. We could reliably catch them on a seasonal basis, and we could keep the animals alive in our specialised aquarium system for months at a time. P. pileus spends most of the time in an inactive drifting state which is interspersed with periods of one of 5 active behaviours. The most common active behaviours are tentacle resetting and feeding. The longest duration behaviours include swimming up or down. Time of day does not appear to alter their behavioural profile. Gaining a better understanding of the behaviour of these animals has important implications for systems and evolutionary neuroscience.

neuroscience↗

bioRxiv2018

The Flexiscope: a Low Cost, Flexible, Convertible, and Modular Microscope with Automated Scanning and Micromanipulation.

With technologies rapidly evolving, many research institutions are now opting to invest in costly, high-quality, specialised microscopes which are shared by many researchers. As a consequence, the user may not have the ability to adapt a microscope to their specific needs and limitations in experimental design are introduced. A flexible work-horse microscopy system is a valuable tool in any laboratory to meet the diverse needs of a research team and promote innovation in experimental design. We have developed the Flexiscope; a multi-functional, adaptable, efficient and high-performance microscopy/electrophysiology system for everyday applications in a neurobiology laboratory. The core optical components are relatively constant in the three configurations described here; an upright configuration, an inverted configuration and an upright/electrophysiology configuration. We have provided a comprehensive description of the Flexiscope. We show that this method is capable of oblique infrared illumination imaging, multi-channel fluorescent imaging, and automated 3D scanning of larger specimens. Image quality is conserved across the three configurations of the microscope, and conversion between configurations is possible quickly and easily, while the motion control system can be repurposed to allow sub-micron computer-controlled micromanipulation. The Flexiscope provides similar performance and usability to commercially available systems. However, as it can be easily reconfigured for multiple roles, it can remove the need to purchase multiple microscopes, giving significant cost savings. The modular re-configurable nature allows the user to customise the system to their specific needs and adapt/upgrade the system as challenges arise, without requiring specialised technical skills.

neuroscience↗