Genetically engineered fish with enhanced phenotypic traits have yet to be implemented into comme... more Genetically engineered fish with enhanced phenotypic traits have yet to be implemented into commercial applications. This is partly because of the difficulties in reliably predicting the ecological risk of transgenic fish should they escape into the wild. The ecological consequences of the phenotypic differences between transgenic and wild-type fish, as determined in the laboratory, can be uncertain because of genotype-by-environment effects (GXE). Additionally, we are limited in our ability to extrapolate simple phenotypes to the complex ecological interactions that occur in nature. Genetic background can also shape the phenotypic effects of transgenes, which, over time and among different wild populations, can make risk assessments a continuously evolving target. These uncertainties suggest that assessments of transgenic fish in contained facilities need to be conducted under as wide a range of conditions as possible, and that efficacious physical and biological containment strategies remain as crucial approaches to ensure the safe application of transgenic fish technology.
Ecological implications of genetically modified fishes in freshwater fisheries, with a focus on s... more Ecological implications of genetically modified fishes in freshwater fisheries, with a focus on salmonids
General and Comparative Endocrinology, Mar 1, 2003
Food availability for wild organisms typically varies both in time and space, requiring a mechani... more Food availability for wild organisms typically varies both in time and space, requiring a mechanism that regulates the storage of excess energy and makes it possible to use stores during energy shortfall. Leptin, a protein hormone encoded by an obesity gene, has been suggested to be the signal mediator for this flux of energy. In a controlled laboratory experiment on caged great tits (Parus major) we evaluated the effect of leptin on food intake and behaviour. Experimental birds were given an intramuscular injection of 10 microg leptin dissolved in phosphate buffered saline (PBS), while the control birds were injected with PBS only at 09:00 h after a night's fasting. Within the first 20 min after injections we observed a significant difference in food intake between groups: control birds initially fed at higher rates compared to leptin treated birds. The cumulative food intake suggested that the effect of leptin disappeared after approximately 40-50 min post-injections. Similar results have previously been found in domesticated chickens. To our knowledge, this is the first study to show that leptin depresses food intake in wild birds.
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, Jun 18, 2016
Environmental warming and acute stress increase cardiorespiratory activity in ectothermic animals... more Environmental warming and acute stress increase cardiorespiratory activity in ectothermic animals like fish. While thermal acclimation can buffer the direct thermal effects on basal cardiorespiratory function during chronic warming, little is known about how acclimation affects stress-induced cardiorespiratory responses. We compared cardiovascular and haematological responses to chasing stress in cannulated wild European perch (Perca fluviatilis) from a reference area at natural temperature (16 °C) with perch from the 'Biotest enclosure'; an experimental system chronically warmed (22 °C) by effluents from a nuclear power plant. Routine blood pressure was similar, but Biotest perch had slightly higher resting heart rate (59.9 ± 2.8 vs 51.3 ± 2.9 beats min(-1)), although the Q 10 for heart rate was 1.3, indicating pronounced thermal compensation. Chasing stress caused hypertension and a delayed tachycardia in both groups, but the maximum heart rate increase was 2.5-fold greater in Biotest fish (43.3 ± 4.3 vs 16.9 ± 2.7 beats min(-1)). Moreover, the pulse pressure response after stress was greater in reference fish, possibly due to the less pronounced tachycardia or a greater ventricular pressure generating capacity and thermally mediated differences in aortic compliance. Baseline haematological status was also similar, but after chasing stress, the haematocrit was higher in Biotest fish due to exacerbated red blood cell swelling. This study highlights that while eurythermal fishes can greatly compensate routine cardiorespiratory functions through acclimation processes, stress-induced responses may still differ markedly. This knowledge is essential when utilising cardiorespiratory variables to quantify and compare stress responses across environmental temperatures, and to forecast energetic costs and physiological constraints in ectothermic animals under global warming.
Mitochondria are playing key roles in setting the thermal limits of fish, but how these organelle... more Mitochondria are playing key roles in setting the thermal limits of fish, but how these organelles participate in selection mechanisms during extreme thermal events associated with climate warming in natural populations is unclear. Here, we investigated the thermal effects on mitochondrial metabolism, oxidative stress, and mitochondrial gene expression in cardiac tissues of European perch (Perca fluviatilis) collected from an artificially heated ecosystem, the “Biotest enclosure”, and an adjacent reference area in the Baltic sea with normal temperatures (~ 23 °C and ~ 16 °C, respectively, at the time of capture in summer). Fish were sampled one month after a heat wave that caused the Biotest temperatures to peak at ~ 31.5 °C, causing significant mortality. When assayed at 23 °C, Biotest perch maintained high mitochondrial capacities, while reference perch displayed depressed mitochondrial functions relative to measurements at 16 °C. Moreover, mitochondrial gene expression of nd4 (mi...
Some evidence suggests that cardiac mitochondrial functions might be involved in the resilience o... more Some evidence suggests that cardiac mitochondrial functions might be involved in the resilience of ectotherms such as fish to environmental warming. Here, we investigated the effects of acute and chronic changes in thermal regimes on cardiac mitochondrial plasticity and thermal sensitivity in perch (Perca fluviatilis) from an artificially heated ecosystem; the “Biotest enclosure” (~25 °C), and from an adjacent area in the Baltic Sea with normal temperatures (reference, ~16 °C). We evaluated cardiac mitochondrial respiration at assay temperatures of 16 and 25 °C, as well as activities of lactate dehydrogenase (LDH) and citrate synthase (CS) in Biotest and reference perch following 8 months laboratory-acclimation to either 16 or 25 °C. While both populations exhibited higher acute mitochondrial thermal sensitivity when acclimated to their natural habitat temperatures, this sensitivity was lost when Biotest and reference fish were acclimated to 16 and 25 °C, respectively. Moreover, ref...
Understanding the resilience of aquatic ectothermic animals to climate warming has been hindered ... more Understanding the resilience of aquatic ectothermic animals to climate warming has been hindered by the absence of experimental systems experiencing warming across relevant timescales (for example, decades). Here, we examine European perch (Perca fluviatilis, L.) from the Biotest enclosure, a unique coastal ecosystem that maintains natural thermal fluctuations but has been warmed by 5–10 °C by a nuclear power plant for over three decades. We show that Biotest perch grow faster and display thermally compensated resting cardiorespiratory functions compared with reference perch living at natural temperatures in adjacent waters. However, maximum cardiorespiratory capacities and heat tolerance limits exhibit limited or no thermal compensation when compared with acutely heated reference perch. We propose that while basal energy requirements and resting cardiorespiratory functions (floors) are thermally plastic, maximum capacities and upper critical heat limits (ceilings) are much less fle...
Experiments examining potential impacts of growth hormone (GH) transgenesis in fish typically use... more Experiments examining potential impacts of growth hormone (GH) transgenesis in fish typically use a single source strain, and do not address potential differential impacts in strains of different genetic backgrounds. Here, we examine the effects of differing genetic backgrounds on the growth of transgenic and non-transgenic coho salmon produced by mating sires from different rivers with transgenic dams from a single origin. We found a significant difference in size between offspring of sires originating from various river systems in British Columbia. This difference was independent of differences between transgenotypes (i.e., transgenic vs. non-transgenic offspring). However, the effects of strain or sire were relatively small compared to the effects of the transgene, which were consistent regardless of sire origin. Thus, results derived from studies of GH transgenic fish from a single source pouplation could provide useful information for assessments of GH transgenic salmon from ot...
The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonid... more The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonids generally become less active during this period, and while food intake continues to some extent, growth rates are typically low. Here we present the results of an over-winter field experiment where energy levels were manipulated in late autumn. Three groups of juvenile (age 1+) brown trout, from an anadromous population, were monitored with respect to over-winter growth rate and survival (as indicated by recapture rates). Two groups were fed either high (HR), or low (LR) food rations in the laboratory for a month (October); the third group remained in the stream (STR). Over-winter growth rates were relatively low in all groups, and no growth compensation could be detected. Compared to HR and LR, STR fish had higher recapture rates after winter, indicating that laboratory housing may have affected the subsequent stream survival negatively. Comparing the two laboratory-housed groups, the LR group reached similar condition as the HR group in early spring, without indications of differences in survival. However, the initiation rate of body silvering (indicating initiation of smoltification) was lower in the LR group. Thus, it appears that food restriction during late autumn affect the onset of smoltification in juvenile brown trout. The results support previous laboratory studies indicating that salmonids modify their over-winter foraging behaviour to avoid too low energy levels at the end of winter. This modification appears to delay smoltification, but may not necessarily be costly in terms of over-winter mortality.
Page 1. c09 BLBS039-Overturf June 10, 2009 10:51 Printer Name: Yet to Come Chapter 9 Issues and M... more Page 1. c09 BLBS039-Overturf June 10, 2009 10:51 Printer Name: Yet to Come Chapter 9 Issues and Methodology for Development of Transgenic Fish for Aquaculture with a Focus on Growth Enhancement Robert H. Devlin ...
Environmental risk assessment of genetically modified organisms, Volume 3. Methodologies for transgenic fish, 2007
This chapter addresses the methodologies for assessing the potential ecological effects of transg... more This chapter addresses the methodologies for assessing the potential ecological effects of transgenic fish before they actually enter unconfined environments. A strategy for identifying the most important data is outlined, and methods for generating them are presented. The following are also discussed: types of information needed to accurately characterize potential receiving environments for the transgenic fish; phenotypic characteristics of transgenic fish that will influence their interaction with ecosystem processes and components; experimental approaches for assessing transgenic fish phenotypes and their ecological impact; and major sources of scientific uncertainty influencing empirical assessments.
Genetically engineered fish with enhanced phenotypic traits have yet to be implemented into comme... more Genetically engineered fish with enhanced phenotypic traits have yet to be implemented into commercial applications. This is partly because of the difficulties in reliably predicting the ecological risk of transgenic fish should they escape into the wild. The ecological consequences of the phenotypic differences between transgenic and wild-type fish, as determined in the laboratory, can be uncertain because of genotype-by-environment effects (GXE). Additionally, we are limited in our ability to extrapolate simple phenotypes to the complex ecological interactions that occur in nature. Genetic background can also shape the phenotypic effects of transgenes, which, over time and among different wild populations, can make risk assessments a continuously evolving target. These uncertainties suggest that assessments of transgenic fish in contained facilities need to be conducted under as wide a range of conditions as possible, and that efficacious physical and biological containment strategies remain as crucial approaches to ensure the safe application of transgenic fish technology.
Ecological implications of genetically modified fishes in freshwater fisheries, with a focus on s... more Ecological implications of genetically modified fishes in freshwater fisheries, with a focus on salmonids
General and Comparative Endocrinology, Mar 1, 2003
Food availability for wild organisms typically varies both in time and space, requiring a mechani... more Food availability for wild organisms typically varies both in time and space, requiring a mechanism that regulates the storage of excess energy and makes it possible to use stores during energy shortfall. Leptin, a protein hormone encoded by an obesity gene, has been suggested to be the signal mediator for this flux of energy. In a controlled laboratory experiment on caged great tits (Parus major) we evaluated the effect of leptin on food intake and behaviour. Experimental birds were given an intramuscular injection of 10 microg leptin dissolved in phosphate buffered saline (PBS), while the control birds were injected with PBS only at 09:00 h after a night's fasting. Within the first 20 min after injections we observed a significant difference in food intake between groups: control birds initially fed at higher rates compared to leptin treated birds. The cumulative food intake suggested that the effect of leptin disappeared after approximately 40-50 min post-injections. Similar results have previously been found in domesticated chickens. To our knowledge, this is the first study to show that leptin depresses food intake in wild birds.
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, Jun 18, 2016
Environmental warming and acute stress increase cardiorespiratory activity in ectothermic animals... more Environmental warming and acute stress increase cardiorespiratory activity in ectothermic animals like fish. While thermal acclimation can buffer the direct thermal effects on basal cardiorespiratory function during chronic warming, little is known about how acclimation affects stress-induced cardiorespiratory responses. We compared cardiovascular and haematological responses to chasing stress in cannulated wild European perch (Perca fluviatilis) from a reference area at natural temperature (16 °C) with perch from the 'Biotest enclosure'; an experimental system chronically warmed (22 °C) by effluents from a nuclear power plant. Routine blood pressure was similar, but Biotest perch had slightly higher resting heart rate (59.9 ± 2.8 vs 51.3 ± 2.9 beats min(-1)), although the Q 10 for heart rate was 1.3, indicating pronounced thermal compensation. Chasing stress caused hypertension and a delayed tachycardia in both groups, but the maximum heart rate increase was 2.5-fold greater in Biotest fish (43.3 ± 4.3 vs 16.9 ± 2.7 beats min(-1)). Moreover, the pulse pressure response after stress was greater in reference fish, possibly due to the less pronounced tachycardia or a greater ventricular pressure generating capacity and thermally mediated differences in aortic compliance. Baseline haematological status was also similar, but after chasing stress, the haematocrit was higher in Biotest fish due to exacerbated red blood cell swelling. This study highlights that while eurythermal fishes can greatly compensate routine cardiorespiratory functions through acclimation processes, stress-induced responses may still differ markedly. This knowledge is essential when utilising cardiorespiratory variables to quantify and compare stress responses across environmental temperatures, and to forecast energetic costs and physiological constraints in ectothermic animals under global warming.
Mitochondria are playing key roles in setting the thermal limits of fish, but how these organelle... more Mitochondria are playing key roles in setting the thermal limits of fish, but how these organelles participate in selection mechanisms during extreme thermal events associated with climate warming in natural populations is unclear. Here, we investigated the thermal effects on mitochondrial metabolism, oxidative stress, and mitochondrial gene expression in cardiac tissues of European perch (Perca fluviatilis) collected from an artificially heated ecosystem, the “Biotest enclosure”, and an adjacent reference area in the Baltic sea with normal temperatures (~ 23 °C and ~ 16 °C, respectively, at the time of capture in summer). Fish were sampled one month after a heat wave that caused the Biotest temperatures to peak at ~ 31.5 °C, causing significant mortality. When assayed at 23 °C, Biotest perch maintained high mitochondrial capacities, while reference perch displayed depressed mitochondrial functions relative to measurements at 16 °C. Moreover, mitochondrial gene expression of nd4 (mi...
Some evidence suggests that cardiac mitochondrial functions might be involved in the resilience o... more Some evidence suggests that cardiac mitochondrial functions might be involved in the resilience of ectotherms such as fish to environmental warming. Here, we investigated the effects of acute and chronic changes in thermal regimes on cardiac mitochondrial plasticity and thermal sensitivity in perch (Perca fluviatilis) from an artificially heated ecosystem; the “Biotest enclosure” (~25 °C), and from an adjacent area in the Baltic Sea with normal temperatures (reference, ~16 °C). We evaluated cardiac mitochondrial respiration at assay temperatures of 16 and 25 °C, as well as activities of lactate dehydrogenase (LDH) and citrate synthase (CS) in Biotest and reference perch following 8 months laboratory-acclimation to either 16 or 25 °C. While both populations exhibited higher acute mitochondrial thermal sensitivity when acclimated to their natural habitat temperatures, this sensitivity was lost when Biotest and reference fish were acclimated to 16 and 25 °C, respectively. Moreover, ref...
Understanding the resilience of aquatic ectothermic animals to climate warming has been hindered ... more Understanding the resilience of aquatic ectothermic animals to climate warming has been hindered by the absence of experimental systems experiencing warming across relevant timescales (for example, decades). Here, we examine European perch (Perca fluviatilis, L.) from the Biotest enclosure, a unique coastal ecosystem that maintains natural thermal fluctuations but has been warmed by 5–10 °C by a nuclear power plant for over three decades. We show that Biotest perch grow faster and display thermally compensated resting cardiorespiratory functions compared with reference perch living at natural temperatures in adjacent waters. However, maximum cardiorespiratory capacities and heat tolerance limits exhibit limited or no thermal compensation when compared with acutely heated reference perch. We propose that while basal energy requirements and resting cardiorespiratory functions (floors) are thermally plastic, maximum capacities and upper critical heat limits (ceilings) are much less fle...
Experiments examining potential impacts of growth hormone (GH) transgenesis in fish typically use... more Experiments examining potential impacts of growth hormone (GH) transgenesis in fish typically use a single source strain, and do not address potential differential impacts in strains of different genetic backgrounds. Here, we examine the effects of differing genetic backgrounds on the growth of transgenic and non-transgenic coho salmon produced by mating sires from different rivers with transgenic dams from a single origin. We found a significant difference in size between offspring of sires originating from various river systems in British Columbia. This difference was independent of differences between transgenotypes (i.e., transgenic vs. non-transgenic offspring). However, the effects of strain or sire were relatively small compared to the effects of the transgene, which were consistent regardless of sire origin. Thus, results derived from studies of GH transgenic fish from a single source pouplation could provide useful information for assessments of GH transgenic salmon from ot...
The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonid... more The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonids generally become less active during this period, and while food intake continues to some extent, growth rates are typically low. Here we present the results of an over-winter field experiment where energy levels were manipulated in late autumn. Three groups of juvenile (age 1+) brown trout, from an anadromous population, were monitored with respect to over-winter growth rate and survival (as indicated by recapture rates). Two groups were fed either high (HR), or low (LR) food rations in the laboratory for a month (October); the third group remained in the stream (STR). Over-winter growth rates were relatively low in all groups, and no growth compensation could be detected. Compared to HR and LR, STR fish had higher recapture rates after winter, indicating that laboratory housing may have affected the subsequent stream survival negatively. Comparing the two laboratory-housed groups, the LR group reached similar condition as the HR group in early spring, without indications of differences in survival. However, the initiation rate of body silvering (indicating initiation of smoltification) was lower in the LR group. Thus, it appears that food restriction during late autumn affect the onset of smoltification in juvenile brown trout. The results support previous laboratory studies indicating that salmonids modify their over-winter foraging behaviour to avoid too low energy levels at the end of winter. This modification appears to delay smoltification, but may not necessarily be costly in terms of over-winter mortality.
Page 1. c09 BLBS039-Overturf June 10, 2009 10:51 Printer Name: Yet to Come Chapter 9 Issues and M... more Page 1. c09 BLBS039-Overturf June 10, 2009 10:51 Printer Name: Yet to Come Chapter 9 Issues and Methodology for Development of Transgenic Fish for Aquaculture with a Focus on Growth Enhancement Robert H. Devlin ...
Environmental risk assessment of genetically modified organisms, Volume 3. Methodologies for transgenic fish, 2007
This chapter addresses the methodologies for assessing the potential ecological effects of transg... more This chapter addresses the methodologies for assessing the potential ecological effects of transgenic fish before they actually enter unconfined environments. A strategy for identifying the most important data is outlined, and methods for generating them are presented. The following are also discussed: types of information needed to accurately characterize potential receiving environments for the transgenic fish; phenotypic characteristics of transgenic fish that will influence their interaction with ecosystem processes and components; experimental approaches for assessing transgenic fish phenotypes and their ecological impact; and major sources of scientific uncertainty influencing empirical assessments.
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