Heart rate logger implantation to report entrainment (phase adjustment) of circadian rhythm in Atlantic salmon parr
Purpose:
An endogenous biological oscillator, known as a circadian (24 h) rhythm, drives daily cycles of physiology, including resting heart rate and the immune response. This biological rhythm needs to be synchronized with the daily environment, and for most organisms, the most important synchronizing factor is the daily light / dark cycle (ref1). Disturbance of the daily light / dark cycle can disrupt the circadian rhythm and negatively affect the physiological outputs it controls (ref2). In mammals, light driven disruption of the circadian clock by exposure to constant light negatively effects the immune response (ref3). However despite the fact that constant light is used routinely in aquaculture, the relationship between light, circadian rhythms, and immune function is unexplored in salmonids.
To address this knowledge gap we first need to establish a safe and effective method to monitor outputs from the circadian rhythm within individual salmon. This will provide data about how circadian outputs are regulated under different lighting conditions, including constant light. Heart rate provides a clear circadian rhythm output, and provides a means of monitoring acute stress as heart rate is correlated positively with stress hormone levels (refs4,5). To measure heart rate, we will use a miniaturized heart rate logger (Star Oddi, DST-microHRT). We here apply for a pilot study to test whether implanting a miniaturized heart rate logger will effect welfare and performance of 130g Atlantic salmon parr.
ref1 K. B. Koronowski et al., (2021) Science (80-92). vol. 371, no. 6530, p. eabd0951
ref2 T. A. Martino et al., (2008) Am. J. Physiol. Regul. Integr. Comp. Physiol., vol. 294, no. 5, pp. 1675–1683
ref3 H. Mizutani et al., (2017) J. Dermatol. Sci., vol. 86, no. 1, pp. 63–70
ref4 M. Hvas et al., (2020) Aquaculture, vol. 529, no. April, p. 735630
ref5 E. Svendsen et al., (2020) Aquaculture, vol. 531, no. August 2020, p. 735804
Distress:
Atlantic salmon parr (~130g) will be surgically implanted with a miniaturised heart rate logger.
Expected benefit:
A high resolution measure of heart rate. Providing a measure of circadian phase and stress.
Number of animals, and what kind:
Ten Atlantic salmon parr (130g) for surgery. 50 additional fish will be added to the tanks to avoid the potentially negative emergence of a social hierarchy.
How to adhere to 3R:
Replacement - there is no suitable in vitro approach
Reduction - before undertaking a larger study, we apply for a pilot study on a small trial (10 fish) to assess the impact of implantation
Refinement - we will test the implementation of cutting edge implantable logging devices which, if successful, will improve the design of future experiments and make them more informative
An endogenous biological oscillator, known as a circadian (24 h) rhythm, drives daily cycles of physiology, including resting heart rate and the immune response. This biological rhythm needs to be synchronized with the daily environment, and for most organisms, the most important synchronizing factor is the daily light / dark cycle (ref1). Disturbance of the daily light / dark cycle can disrupt the circadian rhythm and negatively affect the physiological outputs it controls (ref2). In mammals, light driven disruption of the circadian clock by exposure to constant light negatively effects the immune response (ref3). However despite the fact that constant light is used routinely in aquaculture, the relationship between light, circadian rhythms, and immune function is unexplored in salmonids.
To address this knowledge gap we first need to establish a safe and effective method to monitor outputs from the circadian rhythm within individual salmon. This will provide data about how circadian outputs are regulated under different lighting conditions, including constant light. Heart rate provides a clear circadian rhythm output, and provides a means of monitoring acute stress as heart rate is correlated positively with stress hormone levels (refs4,5). To measure heart rate, we will use a miniaturized heart rate logger (Star Oddi, DST-microHRT). We here apply for a pilot study to test whether implanting a miniaturized heart rate logger will effect welfare and performance of 130g Atlantic salmon parr.
ref1 K. B. Koronowski et al., (2021) Science (80-92). vol. 371, no. 6530, p. eabd0951
ref2 T. A. Martino et al., (2008) Am. J. Physiol. Regul. Integr. Comp. Physiol., vol. 294, no. 5, pp. 1675–1683
ref3 H. Mizutani et al., (2017) J. Dermatol. Sci., vol. 86, no. 1, pp. 63–70
ref4 M. Hvas et al., (2020) Aquaculture, vol. 529, no. April, p. 735630
ref5 E. Svendsen et al., (2020) Aquaculture, vol. 531, no. August 2020, p. 735804
Distress:
Atlantic salmon parr (~130g) will be surgically implanted with a miniaturised heart rate logger.
Expected benefit:
A high resolution measure of heart rate. Providing a measure of circadian phase and stress.
Number of animals, and what kind:
Ten Atlantic salmon parr (130g) for surgery. 50 additional fish will be added to the tanks to avoid the potentially negative emergence of a social hierarchy.
How to adhere to 3R:
Replacement - there is no suitable in vitro approach
Reduction - before undertaking a larger study, we apply for a pilot study on a small trial (10 fish) to assess the impact of implantation
Refinement - we will test the implementation of cutting edge implantable logging devices which, if successful, will improve the design of future experiments and make them more informative