Biology subjects

Thompson, W. A.

Publications and source records attributed to Thompson, W. A..

4 recordsLinked to original sources

bioRxiv2024

The marine worm Capitella teleta is sensitive to neurochemical manipulation, as revealed via a novel high-throughput behavioural tool

Anthropogenic impacts have led to increases in contaminants in marine habitats. The presence of compounds such as pharmaceuticals, personal care products, and pesticides is a concern, as these compounds have been shown to act as neurochemicals in aquatic organisms. However, screens of the multitude of chemicals found environmentally have yet to be carried out. Capitella teleta are marine annelid polychaete worms that live in the sediment of estuarian environments, acting as ecosystem engineers for marine habitats. This study aimed to develop a behaviour tool to identify neurochemical pathways involved in controlling locomotion that could be applied to screen the impacts of toxicants in the environment using this key invertebrate species at multiple life stages. Adult and juvenile life stages (2 weeks post-emergence) of Capitella teleta were observed in Petri dishes (adults only) or 6-well plates (adults and juveniles), and conserved behavioural responses were isolated, such as their velocity, distance travelled, the time to reach the edge of the arena, and time spent at the periphery. We exposed juvenile and adult worms to nicotine (acetylcholine agonist) as a proof of concept. We noted similar disruptions to locomotion at both life stages, with low doses of nicotine stimulating movement and higher doses reducing locomotion. From here, we exposed juvenile worms to fluoxetine (serotonin reuptake inhibitor), phenobarbital (GABA agonist), and apomorphine (dopamine agonist). The behaviour of juvenile worms can be altered by exposure to fluoxetine, phenobarbital, and apomorphine. Fluoxetine and phenobarbital exposure reduces movement at high doses, but fluoxetine influences the amount of time at the periphery of the arena. Apomorphine produced modest changes in locomotion compared to other chemicals tested. Genome searching, as well as transcriptomics, were used to confirm the presence of neurochemical pathways in Capitella teleta. Our results demonstrate that Capitella teleta is a viable model for behavioural work, that several neurochemical pathways contribute to locomotory behaviour, and that this assay may be useful as a screen for contaminants found in marine habitats.

animal behavior and cognition↗

bioRxiv2024

Elevated temperature during rearing diminishes swimming and disturbs the metabolism of yellow perch larvae

Temperate waters, such as the Great Lakes, are predicted to increase by 1{degrees}C every decade. Poikilothermic fish thermoregulate behaviourally, moving to more suitable thermal environments. Embryos are incapable of locomotion and may be exposed to non-optimal temperatures during development. Increased temperature alters the normal development of the yellow perch (Perca flavescens), however, whether altered incubation temperature influences the development of metabolism and function in these fish remains unknown. We hypothesized that increased embryonic incubation temperature would disturb cardiac and metabolic function and the behaviour of yellow perch larvae. We reared yellow perch embryos at 12{degrees}C, 15{degrees}C, or 18{degrees}C until hatching; after hatching, the temperature was raised to a common garden 18{degrees}C, their preferred post-hatch temperature. We assessed exploratory behaviour, metabolism (oxygen consumption), and cardiac performance throughout early development. At hatch, 12{degrees}C fish exhibited the greatest swimming activity, with 18{degrees}C fish consuming the least oxygen and possibly experiencing mitochondrial dysfunction. Cardiac development was more advanced at hatch in 18{degrees}C fish. Yet, warmer incubated fish had diminished movement and increased oxygen consumption at 20 days post-hatch, demonstrating long-term disruptions of increased temperature in the embryonic environment. Overall, elevations in rearing temperature may cause metabolic dysfunction and behavioural alterations, potentially impacting the survival of yellow perch.

developmental biology↗

bioRxiv2023

Metformin and guanylurea reduce survival, but have limited sublethal effects in larval zebrafish (Danio rerio)

Metformin is the most common first-line oral therapeutic agent used in the treatment of type-2 diabetes, one of the most prevalent chronic diseases in North America. Post excretion, the compound enters wastewater treatment plants where it is partially bio-transformed by bacteria into guanylurea. Both metformin and guanylurea enter freshwater environments in wastewater effluent where they are available for uptake by aquatic biota. However, our understanding of the effects of metformin and guanylurea on aquatic life is limited. We tested the hypothesis that metformin and guanylurea can influence the development of zebrafish (Danio rerio), by assessing morphometrics, cardiac development, energetic state, and behaviour of early larvae. Embryos were exposed to environmentally relevant (0.4, 4, 40 g{middle dot}L-1) and supra-environmental (400 and 4000 g{middle dot}L-1) concentrations of metformin and guanylurea from the 4-cell stage (3 hours post fertilization; hpf), until first feed (120 hpf). Exposures to 40 g{middle dot}L-1and higher of both metformin and guanylurea increased mortality. Metformin delayed hatching at the highest concentration tested (4000 g{middle dot}L-1). The incidence of spinal curvature increased with exposure to both chemicals at supra-environmental levels (400 and 4000 g{middle dot}L-1 for metformin; 400 g{middle dot}L-1 for guanylurea). Metformin and guanylurea exposure imposed slight bradycardia in early development, but did not alter oxygen consumption, ATP levels, carbohydrate levels, general swimming, light-dark movement, startle response, or thigmotaxis, irrespective of exposure concentration. The results suggest similar and low sensitivities of larval fish to both metformin and guanylurea. Apart from a small increase in mortality, these compounds impart a modest impact to the early-life stages of zebrafish that are largely limited to supra-environmental concentrations.

pharmacology and toxicology↗

bioRxiv2023

Effect of elevated embryonic incubation temperature on the temperature preference of juvenile lake (Coregonus clupeaformis) and round whitefish (Prosopium cylindraceum)

Anthropogenic impacts can lead to increased temperatures in freshwater environments through thermal effluent and climate change. Thermal preference of aquatic organisms can be modulated by abiotic and biotic factors including environmental temperature. Whether increased temperature during embryogenesis can lead to long-term alterations in thermal preference has not been explicitly tested in native freshwater species. Lake (Coregonus clupeaformis) and round (Prosopium cylindraceum) whitefish were incubated at natural and elevated temperatures until hatching, following which, all groups were moved to common garden conditions (15{degrees}C) during the post-hatching stage. Temperature preference was determined at 8 (Lake whitefish only) and 12-months of age (both species), using a shuttlebox system. Round whitefish preferred a cooler temperature when incubated at 2{degrees}C and 6{degrees}C compared to 0.5{degrees}C. Lake whitefish had similar temperature preferences regardless of age, weight, and incubation temperature. These results reveal that temperature preference in freshwater fish can be programmed during early development, and that round whitefish may be more sensitive to incubation temperature. This study highlights the effects that small increases in temperature caused by anthropogenic impacts may have on cold-adapted freshwater fish.

animal behavior and cognition↗