Biology subjects

Lawrence, M. J.

Publications and source records attributed to Lawrence, M. J..

6 recordsLinked to original sources

bioRxiv2024

Behavioural responses to acute warming precede critical shifts in the cellular and physiological thermal stress responses in fish

From a conservation perspective, it is important to identify when sub-lethal temperatures begin to adversely impact an organism. However, it is unclear whether, during acute exposures, these cellular thresholds occur at similar temperatures to other physiological or behavioural changes. To test this, we estimated temperature preference (15.1 {+/-} 1.1 {degrees}C) using a shuttle box, thermal optima for aerobic scope (10-15 {degrees}C) using respirometry, agitation temperature (22.0 {+/-} 1.4 {degrees}C) as the point where a fish exhibits a behavioural avoidance response and the CTmax (28.2 {+/-} 0.4 {degrees}C) as the upper thermal limit for 1 yr old Brook Trout (Salvelinus fontinalis) acclimated to 10 {degrees}C. We then acutely exposed a different subset of fish to these temperatures and sampled tissues when they reached the target temperature or after 60 min of recovery at 10 {degrees}C. We used qPCR to estimate mRNA transcript levels of genes associated with heat shock proteins, oxidative stress, apoptosis, and inducible transcription factors. A major shift in the transcriptome response occurred near the agitation temperature, which may identify a link between the cellular stress response and the behavioural avoidance response.

physiology↗

bioRxiv2023

Differences in the transcriptome response in the gills of sea lamprey acutely exposed to 3-trifluoromethyl-4-nitrophenol (TFM), niclosamide or a TFM:niclosamide mixture

Sea lamprey (Petromyzon marinus) control in the Laurentian Great Lakes of North America makes use of two pesticides: 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide, which are often co-applied. Sea lamprey appear to be vulnerable to these agents resulting from a lack of detoxification responses with evidence suggesting that lampricide mixtures produce a synergistic effect. However, there is a lack of information pertaining to the physiological responses of sea lamprey to niclosamide and TFM:niclosamide mixtures. Here, we characterized the transcriptomic responses of the sea lamprey to TFM, niclosamide, and a TFM:niclosamide (1.5%) mixture in the gill. Along with a control, larval sea lamprey were exposed to each treatment for 6 h, after which gill tissues were extracted for measuring whole-transcriptome responses using RNA sequencing. Differential gene expression patterns were summarized, which included identifying the broad roles of genes and common expression patterns among the treatments. While niclosamide treatment resulted in no differentially expressed genes, TFM- and mixture-treated fish had several differentially expressed genes that were associated with the cell cycle, DNA damage, metabolism, immune function, and detoxification. However, there was no common differential expression among treatments. For the first time, we characterized the transcriptomic response of sea lamprey to niclosamide and a TFM:niclosamide mixture and identified that these agents impact mRNA transcript abundance of genes associated with the cell cycle and cellular death, and immune function, which are likely mediated through mitochondrial dysregulation. These results may help to inform the production of more targeted and effective lampricides in sea lamprey control efforts.

genomics↗

bioRxiv2023

The fate of intracoelomic acoustic transmitters in Atlantic Salmon (Salmo salar) post-smolts and wider considerations for casual factors driving tag retention and mortality in fishes

Acoustic telemetry is a widely used method in assaying behavioural dynamics in fishes. Telemetry tags are often surgically implanted in the coelom of the animal and are assumed to have minimal rates of post-release mortality and tag shedding. However, fish are capable expelling tags and mortalities do occur following release, with the mechanism(s) underlying these effects not well understood. The purpose of this research was to address causal factors underlying tagging mortality and tag expulsion in fishes. We conducted an empirical assessment of tag retention and post-surgical mortality rates in post-smolt Atlantic salmon (Salmo salar) fitted with a dummy acoustic tag over a 92 day monitoring period. This was complimented with a meta-analysis of factors affecting tag retention and post-surgical mortality rates in the wider literature. Post-smolt salmon exhibited low rates of mortality following tag implantation ([≤] 5.1%) but had high rates of tag expulsion (54.8%) and impaired growth and a foreign body response was evident. The meta-analysis showed that mortality was generally low across all studies (12.4%) and was largely unaffected by model cofactors. Tag retention rates were high among the studies investigated here (86.7%) and had a weak negative relationship with tag:body mass ratios. Our results suggest that while mortality is often low among tagging studies, including this one, caution must be exercised in assessing stationary tags as they may represent an expelled tag rather than a mortality event. Our results also indicate that tag dimensions are not nearly important as the tag:body mass ratio.

physiology↗

bioRxiv2023

Transcriptomic impacts and potential routes of detoxification in a lampricide-tolerant teleost exposed to TFM and niclosamide

Sea lamprey (Petromyzon marinus) control in the Laurentian Great Lakes of North America often relies on the application of 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide mixtures to kill larval sea lamprey. Selectivity of TFM against lampreys appears to be due to differential detoxification ability in these jawless fishes compared to bony fishes, particularly teleosts. However, the proximate mechanisms of tolerance to the TFM and niclosamide mixture and the mechanisms of niclosamide toxicity on its own are poorly understood, especially among non-target fishes. Here, we used RNA sequencing to identify specific mRNA transcripts and functional processes that responded to niclosamide or a TFM:niclosamide mixture in bluegill (Lepomis macrochirus). Bluegill were exposed to niclosamide or TFM:niclosamide mixture, along with a time-matched control group, and gill and liver tissues were sampled at 6, 12, and 24 h. We summarized the whole-transcriptome patterns through gene ontology (GO) term enrichment and through differential expression of detoxification genes. The niclosamide treatment resulted in an upregulation of several transcripts associated with detoxification (cyp, ugt, sult, gst), which may help explain the relatively high detoxification capacity in bluegill. Conversely, the TFM:niclosamide mixture resulted in an enrichment of processes related to arrested cell cycle and growth, and cell death alongside a diverse detoxification gene response. Detoxification of both lampricides likely involves the use of phase I and II biotransformation genes. Our findings strongly suggest that the unusually high tolerance of bluegill to lampricides is due to these animals having an inherently high capacity and flexible detoxification response to such compounds.

genomics↗

bioRxiv2021

Variation in the transcriptome response and detoxification gene diversity drives pesticide tolerance in fishes

Pesticides are critical for invasive species management, but often have negative effects on non-target native biota. Tolerance to pesticides should have an evolutionary basis, but this is poorly understood. Invasive sea lamprey (Petromyzon marinus) populations in North America have been controlled with a pesticide lethal to them at lower concentrations than native fishes. We addressed how interspecific variation in gene expression and detoxification gene diversity confer differential pesticide sensitivity in two fish species. We exposed sea lamprey and bluegill (Lepomis macrochirus), a tolerant native species, to TFM, a pesticide commonly used in sea lamprey control, and used whole-transcriptome sequencing of gill and liver to characterize the cellular response. Comparatively, bluegill exhibited a larger number of detoxification genes expressed and a larger number of responsive transcripts overall, which likely contributes to greater tolerance to TFM. Understanding the genetic and physiological basis for pesticide tolerance is crucial for managing invasive species.

genomics↗

bioRxiv2020

Do carbonated beverages reduce bleeding from gill injuries in angled Northern Pike?

The premise of catch-and-release angling is that most fish survive fisheries interactions. Therefore, it is common for anglers, management agencies, and other organizations to share information on handling practices and other strategies that are believed to improve fish welfare and survival. Recent media coverage has sensationalized the use of carbonated beverages to treat bleeding fish, an intervention that is purported to stop bleeding but has yet to be validated scientifically. We captured Northern Pike (Esox lucius) via hook and line, experimentally injured their gills in a standardized manner, and treated them with either Mountain Dew, Coca Cola, or carbonated lake water and observed the duration and intensity of bleeding, as well as overall blood loss (using gill colour as a proxy) while the fish was held in a lake water bath. As a control, we had a group of experimentally injured fish that did not have liquid poured over their gills before the observation period. All treatments and the control were conducted at two different water temperatures (11-18 {degrees}C and 24-27 {degrees}C) to determine if the effects of pouring carbonated beverages over injured gills is temperature dependent. When compared to the control, we found that the duration and intensity of bleeding increased regardless of the type of carbonated beverages used in this study, and there was no effect of water temperature. Use of chilled versus ambient temperature beverages similarly had no influence on outcomes. As such, there is no scientific evidence to support the use of carbonated beverages for reducing or stopping blood loss for fish that have had their gills injured during recreational angling based on the context studied here. This study reinforced the need to scientifically test angler anecdotes and theories when it comes to best practices for catch-and-release fishing.

ecology↗