Browsing by Author "Szaszkiewicz, Joshua"
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Item Analysis of the potential behavioral impact of methanol when used as a solvent: Dataset from zebrafish (Danio rerio) behavioral research(2021) Hamilton, Trevor; Szaszkiewicz, Joshua; Krook, Jeffrey T.; Burggren, WarrenToxicants are commonly administered to experimental organisms using solvents as vehicles. One common vehicle for dissolving toxicants is methanol (CH3OH), a solvent which on its own is capable of altering physiology and behavior high concentrations. This dataset describes behavioral results in zebrafish (Danio rerio) individually exposed to methanol (0.25%, 2.5% vol/vol), or control water, for 30 min prior to behavioral testing. Zebrafish were placed into an open field arena to examine locomotion and zone preference, which was recorded and quantified with motion-tracking software (EthoVision XT). Time spent in the outer (“thigmotaxis”) zone of the arena is a proxy for increased anxiety-like behavior in zebrafish. Additionally, a novel object was placed into the center of the arena to quantify relative increases in boldness/exploration between the methanol and control groups. There were no differences in time spent in any zone of the arena or distance travelled between either group, in either test.Item Coho salmon are behaviourally resilient after 120 days of rearing under altered photoperiods and salinities(2020) Szaszkiewicz, Joshua; Hamilton, Trevor; Krook, Jeffrey T.; Richards, Jeffrey G.; Stiller, Kevin; Brauner, Colin J.; Hamilton, TrevorRecirculating aquaculture systems (RAS) are a sustainable method used in aquaculture to farm healthy stocks of fish intended for market. In order to optimize fish growth, environmental conditions within RAS, including salinity and photoperiod are manipulated. However, little is known about the effect of varying photoperiod and salinity on behaviour. In this study, Coho salmon (Oncorhynchus kisutch) smolts were reared in RAS for 120 days on either a 12 hour light: 12h dark or 24 hour light photoperiod and in salinities of either 2.5, 5, or 10 ppt. An additional group reared in 30 ppt and 24h light was examined. To determine the impact of photoperiod and salinity on behaviour, three behavioural test assays were employed. Locomotion was quantified using an open field test, the novel object approach test was used to quantify boldness, and the light/dark test was used to quantify anxiety-like behaviour. In the open field test we observed no significant differences in locomotion. In the novel object approach test, the 2.5 ppt (12h/12h) group demonstrated decreased boldness relative to the 10 ppt (24h) and 30 ppt (24h) groups. In the light/dark test, the 2.5 (12h/12h) group spent significantly less time in the dark zone. However, no significant differences were observed between any of the treatment groups, suggesting that anxiety-like behaviour was only minimally impacted. Taken together, the photoperiods and salinities investigated did not significantly affect coho salmon behaviour, which has important implications for RAS aquaculture.Item Continuous light (relative to a 12:12 photoperiod) has no effect on anxiety-like behaviour, boldness, and locomotion in coho salmon (Oncorhynchus kisutch) post-smolts in recirculating aquaculture systems at a salinity of either 2.5 or 10 ppt(2022) Hamilton, Trevor; Szaszkiewicz, Joshua; Krook, Jeffrey T.; Richards, Jeffrey G.; Stiller, Kevin; Brauner, Colin J.There is increased interest in rearing salmon in Recirculating Aquaculture Systems (RAS), where environmental conditions can be tightly controlled to optimize growth. Photoperiod and salinity are two important parameters that can be manipulated in RAS. A longer photoperiod permits more time for feeding, while intermediate salinities may reduce the energetic costs of ionoregulation, both of which may enhance growth. However, little is known about how rearing at different photoperiods and salinity affect behaviour, an understudied but important research topic for intensive fish rearing. To address this, we examined the behavioural effects of two salinities and two photoperiod regimes in coho salmon (Oncorhynchus kisutch) post-smolts reared continuously for 120 days in a RAS. Fish were reared on a photoperiod of either 12 h light:12 h dark (12:12), or 24 h light (24:0) at salinities of 2.5 and 10 ppt. To investigate behavioural differences associated with these treatments, we quantified: i) movement in an open-field test, ii) exploratory behaviour/boldness using a novel object approach test, and iii) anxiety-like behaviour with a light/dark test. The 24:0 groups displayed no differences in boldness/anxiety-like behaviour and locomotion relative to the 12:12 groups at their respective salinities. Taken together, fish reared under continuous light (24:0) show negligible behavioural alterations compared to fish reared under normal light dark conditions (12:12).Item Effects of ocean acidification on dopamine-mediated behavioral responses of a coral reef damselfish(2023) Hamilton, Trevor; Tresguerres, Martin; Kwan, Garfield T.; Szaszkiewicz, Joshua; Franczak, Brian C.; Cyronak, Tyler; Andersson, Andreas J.; Kline, David I.We investigated whether CO2-induced ocean acidification (OA) affects dopamine receptor-dependent behavior in bicolor damselfish (Stegastes partitus). Damselfish were kept in aquaria receiving flow through control (pH ~ 8.03; pCO2 ~ 384 μatm) or OA (pH ~ 7.64; CO2 ~ 1100 μatm) seawater at a rate of 1 L min−1. Despite this relatively fast flow rate, fish respiration further acidified the seawater in both control (pH ~7.88; pCO2 ~ 595 μatm) and OA (pH ~7.55; pCO2 ~ 1450 μatm) fish-holding aquaria. After five days of exposure, damselfish locomotion, boldness, anxiety, and aggression were assessed using a battery of behavioral tests using automated video analysis. Two days later, these tests were repeated following application of the dopamine D1 receptor agonist SKF 38393. OA-exposure induced ceiling anxiety levels that were significantly higher than in control damselfish, and SKF 38393 increased anxiety in control damselfish to a level not significantly different than that of OA-exposed damselfish. Additionally, SKF 38393 decreased locomotion and increased boldness in control damselfish but had no effect in OA-exposed damselfish, suggesting an alteration in activity of dopaminergic pathways that regulate behavior under OA conditions. These results indicate that changes in dopamine D1 receptor function affects fish behavior during exposure to OA. However, subsequent measurements of seawater sampled using syringes during the daytime (~3–4 pm local time) from crevasses in coral reef colonies, which are used as shelter by damselfish, revealed an average pH of 7.73 ± 0.03 and pCO2 of 925.8 ± 62.2 μatm; levels which are comparable to Representative Concentration Pathway (RCP) 8.5 predicted end-of-century mean OA levels in the open ocean. Further studies considering the immediate environmental conditions experienced by fish as well as individual variability and effect size are required to understand potential implications of the observed OA-induced behavioral effects on damselfish fitness in the wild.Item Helminth therapy: a promising approach to treating Crohn’s disease and asthma(2020) Szaszkiewicz, JoshuaIncreasing rates of autoimmune diseases, such as asthma and Crohn’s disease, have become a major concern in industrialized countries. One potential cause for the rising rates of autoimmune diseases in humans, is the disconnected relationship to parasites due to better hygiene. The extensive history between parasites and humans has resulted in the evolution of immunomodulating characteristics in parasites that may prevent the development of autoimmune diseases in humans. Here, I discuss the evolutionary reason for the protective effect against autoimmune diseases provided by parasites, explain the hygiene hypothesis as it relates to parasites, and propose the immunological mechanisms of parasites that might confer protection from autoimmune diseases. I will also give evidence for the protective effect and indicate the current state of helminth therapy and its challenges. While helminth therapy may be an effective treatment and prevention method for autoimmune diseases, much more research needs to be conducted in order to determine the specific mechanisms of action on our immune systems, and how these could be used medically to treat autoimmune diseases.Item Shoaling, boldness, anxiety-like behavior and locomotion in zebrafish (Danio rerio) are altered by acute benzo[a]pyrene exposure(2021) Hamilton, Trevor; Szaszkiewicz, Joshua; Krook, Jeffrey T.; Burggren, WarrenEnvironmental exposure to crude oil and/or its derivatives in fishes can negatively impact survival, morphology and physiology, but relatively little focus has been on behavior. Exposures can influence prey-predator interactions, courtship and other vital behaviors, leading to individual or population disruption at toxicant levels well below those producing morphological or physiological changes. The few behavioral studies of polycyclic aromatic hydrocarbons (PAHs) on fish behavior have yielded highly inconsistent results, likely relating to chronic vs. acute treatment. A few studies report lethargy and decreased exploratory behavior, while others indicate increased anxiety and greater exploratory behavior with PAH exposure. In our study on zebrafish (Danio rerio), we hypothesized that even relatively brief (30 min) exposure to the PAH benzo[a]pyrene (B[a]P) would impact group shoaling and individual behaviors in open field and novel object exploration tests. Exposures comprised measured concentrations of 1.0 μM, 10 μM, or 100 μM, B[a]P. Compared to controls, inter-individual distance (IID) was significantly increased by 100 μM B[a]P, but not by 1.0 μM or 10 μM B[a]P. Total distance moved by shoals was decreased significantly at B[a]P concentrations of 1.0 μM, 10 μM and 100 μM. In the open field test of individual locomotion and anxiety-like behavior, time spent in the thigmotaxis zone along the walls of the circular test arena (a proxy for anxiety-like behavior), was decreased at 100 μM. In the novel object approach test to investigate boldness, time spent near the object was significantly increased by both 10 μM and 100 μM B[a]P. Collectively, these data indicate a complex suite of changes in zebrafish including altered shoal dynamics, decreased anxiety, increased boldness, and decreased locomotion associated with exposure to B[a]P.