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Omond SET, Barker RG, Sanislav O, Fisher PR, Annesley SJ, Lesku JA. Oxygen consumption rate of flatworms under the influence of wake- and sleep-promoting neurotransmitters. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024. [PMID: 38801005 DOI: 10.1002/jez.2828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 05/09/2024] [Accepted: 05/09/2024] [Indexed: 05/29/2024]
Abstract
Flatworms are among the best studied animal models for regeneration; however, they also represent an emerging opportunity to investigate other biological processes as well. For instance, flatworms are nocturnal and sleep during the day, a state that is regulated by sleep/wake history and the action of the sleep-promoting neurotransmitter gamma-aminobutyric acid (or GABA). Sleep is widespread across the animal kingdom, where it serves many nonexclusive functions. Notably, sleep saves energy by reducing metabolic rate and by not doing something more energetically taxing. Whether the conservation of energy is apparent in sleeping flatworms is unclear. We measured the oxygen consumption rate (OCR) of flatworms dosed with either (1) GABA (n = 29) which makes flatworms inactive or (2) dopamine (n = 20) which stimulates flatworms to move, or (3) day and night neurotransmitter-free controls (n = 28 and 27, respectively). While OCR did not differ between the day and night, flatworms treated with GABA used less oxygen than those treated with dopamine, and less than the day-time control. Thus, GABA affected flatworm physiology, ostensibly by enforcing energy-conserving sleep. Evidence that dopamine increased metabolism was less strong. This work broadens our understanding of flatworm physiology and expands the phylogenetic applicability of energy conservation as a function of sleep.
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Affiliation(s)
- Shauni E T Omond
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Robert G Barker
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Oana Sanislav
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Paul R Fisher
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Sarah J Annesley
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - John A Lesku
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
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2
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Bullock RW, Foster C, Lea JSE. Just keep swimming? Observations of resting behavior in gray reef sharks Carcharhinus amblyrhynchos (Bleeker, 1856). JOURNAL OF FISH BIOLOGY 2024; 104:898-900. [PMID: 37983935 DOI: 10.1111/jfb.15623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/06/2023] [Accepted: 11/15/2023] [Indexed: 11/22/2023]
Abstract
Understanding the respiratory modes of sharks has important implications for studying the metabolism, energetics, and behavioral strategies of different species. Here we provide the first reported observations of resting behavior in the gray reef shark Carcharhinus amblyrhynchos, a species typically considered an obligate ram ventilator. Observations were made at several locations in the Republic of Seychelles, where sharks were found resting under reef ledges and were unresponsive to the presence of divers. These findings update our understanding of the respiratory mode of this species and have implications for future research.
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Affiliation(s)
- Robert W Bullock
- Save Our Seas Foundation-D'Arros Research Centre, Geneva, Switzerland
| | | | - James S E Lea
- Save Our Seas Foundation, Geneva, Switzerland
- Department of Zoology, University of Cambridge, Cambridge, UK
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3
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Finotto L, Walker TI, Reina RD. The effect of fishing-capture stress on the oxygen uptake rate and swimming activity of the holocephalan Callorhinchus milii. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:203-214. [PMID: 38158379 DOI: 10.1002/jez.2775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 12/06/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024]
Abstract
Overfishing, capture mortality, and consequences following the release of surviving animals represent severe threats to chondrichthyans. Although holocephalans are common bycaught and discarded species, other than postrelease mortality, little is known of fishing capture stress impacts. The stress response elicited after capture, essential to increase survival chances, is energetically demanding and affects the amount of energy available for other biological activities, with potential long-term impairments. We measured the effect of 30-min simulated gillnet capture on oxygen uptake rate (ṀO2 ), a proxy for metabolic rate and energy use, on recovery pattern, and on swimming activity of elephant fish (Callorhinchus milii). Immediately after simulated capture, Active and Inactive ṀO2 , measured during swimming and resting periods, respectively, were 27.5% and 43.1% lower than precapture values. This metabolic decline is likely an adaptation for reducing the energy allocated to non-essential activities, thus preserving it to sustain the stress response and processes essential for immediate survival. Supporting this, after gillnet capture, animals decreased their swimming time by 26.6%, probably due to a reduction in the energy allocated to movement. After 7 days, swimming activity and both Inactive ṀO2 and Active ṀO2 returned to precapture values. Although metabolic decline may enhance survival chances, the associated decreased swimming activity might increase predation risk and slow the physiological recovery after a fishing event. Moreover, some of the activities involved in Inactive ṀO2 are fundamental for life maintenance and therefore its depression after a capture event might have long-term repercussions for life sustenance and health.
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Affiliation(s)
- Licia Finotto
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Terence I Walker
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Richard D Reina
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
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Tan H, Martin JM, Alton LA, Lesku JA, Wong BBM. Widespread psychoactive pollutant augments daytime restfulness and disrupts diurnal activity rhythms in fish. CHEMOSPHERE 2023; 326:138446. [PMID: 36940830 DOI: 10.1016/j.chemosphere.2023.138446] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 06/18/2023]
Abstract
Pharmaceutical pollution is a major driver of global change, with the capacity to alter key behavioural and physiological traits in exposed animals. Antidepressants are among the most commonly detected pharmaceuticals in the environment. Despite well-documented pharmacological effects of antidepressants on sleep in humans and other vertebrates, very little is known about their ecologically relevant impacts as pollutants on non-target wildlife. Accordingly, we investigated the effects of acute 3-day exposure of eastern mosquitofish (Gambusia holbrooki) to field-realistic levels (nominal concentrations: 30 and 300 ng/L) of the widespread psychoactive pollutant, fluoxetine, on diurnal activity patterns and restfulness, as indicators of disruptions to sleep. We show that exposure to fluoxetine disrupted diel activity patterns, which was driven by augmentation of daytime inactivity. Specifically, unexposed control fish were markedly diurnal, swimming farther during the day and exhibiting longer periods and more bouts of inactivity at night. However, in fluoxetine-exposed fish, this natural diel rhythm was eroded, with no differences in activity or restfulness observed between the day and night. As a misalignment in the circadian rhythm has been shown to adversely affect fecundity and lifespan in animals, our findings reveal a potentially serious threat to the survival and reproductive success of pollutant-exposed wildlife.
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Affiliation(s)
- Hung Tan
- School of Biological Sciences, Monash University, Melbourne, Australia.
| | - Jake M Martin
- School of Biological Sciences, Monash University, Melbourne, Australia; Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden; Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Lesley A Alton
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - John A Lesku
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia; Research Centre for Future Landscapes, La Trobe University, Melbourne, Australia
| | - Bob B M Wong
- School of Biological Sciences, Monash University, Melbourne, Australia
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5
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Why study sleep in flatworms? J Comp Physiol B 2023:10.1007/s00360-023-01480-x. [PMID: 36899149 DOI: 10.1007/s00360-023-01480-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/31/2023] [Accepted: 02/23/2023] [Indexed: 03/12/2023]
Abstract
The behaviors that characterize sleep have been observed across a broad range of different species. While much attention has been placed on vertebrates (mostly mammals and birds), the grand diversity of invertebrates has gone largely unexplored. Here, we introduce the intrigue and special value in the study of sleeping platyhelminth flatworms. Flatworms are closely related to annelids and mollusks, and yet are comparatively simple. They lack a circulatory system, respiratory system, endocrine glands, a coelom, and an anus. They retain a central and peripheral nervous system, various sensory systems, and an ability to learn. Flatworms sleep, like other animals, a state which is regulated by prior sleep/wake history and by the neurotransmitter GABA. Furthermore, they possess a remarkable ability to regenerate from a mere fragment of the original animal. The regenerative capabilities of flatworms make them a unique bilaterally symmetric animal to study a link between sleep and neurodevelopment. Lastly, the recent applications of tools for probing the flatworm genome, metabolism, and brain activity make their entrance into the field of sleep research all the more timely.
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Rattenborg NC, Ungurean G. The evolution and diversification of sleep. Trends Ecol Evol 2023; 38:156-170. [PMID: 36411158 DOI: 10.1016/j.tree.2022.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/17/2022] [Accepted: 10/24/2022] [Indexed: 11/19/2022]
Abstract
The evolutionary origins of sleep and its sub-states, rapid eye movement (REM) and non-REM (NREM) sleep, found in mammals and birds, remain a mystery. Although the discovery of a single type of sleep in jellyfish suggests that sleep evolved much earlier than previously thought, it is unclear when and why sleep diversified into multiple types of sleep. Intriguingly, multiple types of sleep have recently been found in animals ranging from non-avian reptiles to arthropods to cephalopods. Although there are similarities between these states and those found in mammals and birds, notable differences also exist. The diversity in the way sleep is expressed confounds attempts to trace the evolution of sleep states, but also serves as a rich resource for exploring the functions of sleep.
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Affiliation(s)
- Niels C Rattenborg
- Max Planck Institute for Biological Intelligence (in foundation), Seewiesen, Germany.
| | - Gianina Ungurean
- Max Planck Institute for Biological Intelligence (in foundation), Seewiesen, Germany
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New Perspectives on Sleep Regulation by Tea: Harmonizing Pathological Sleep and Energy Balance under Stress. Foods 2022; 11:foods11233930. [PMID: 36496738 PMCID: PMC9738644 DOI: 10.3390/foods11233930] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/25/2022] [Accepted: 11/26/2022] [Indexed: 12/09/2022] Open
Abstract
Sleep, a conservative evolutionary behavior of organisms to adapt to changes in the external environment, is divided into natural sleep, in a healthy state, and sickness sleep, which occurs in stressful environments or during illness. Sickness sleep plays an important role in maintaining energy homeostasis under an injury and promoting physical recovery. Tea, a popular phytochemical-rich beverage, has multiple health benefits, including lowering stress and regulating energy metabolism and natural sleep. However, the role of tea in regulating sickness sleep has received little attention. The mechanism underlying tea regulation of sickness sleep and its association with the maintenance of energy homeostasis in injured organisms remains to be elucidated. This review examines the current research on the effect of tea on sleep regulation, focusing on the function of tea in modulating energy homeostasis through sickness sleep, energy metabolism, and damage repair in model organisms. The potential mechanisms underlying tea in regulating sickness sleep are further suggested. Based on the biohomology of sleep regulation, this review provides novel insights into the role of tea in sleep regulation and a new perspective on the potential role of tea in restoring homeostasis from diseases.
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Wheeler CR, Kneebone J, Heinrich D, Strugnell JM, Mandelman JW, Rummer JL. Diel Rhythm and Thermal Independence of Metabolic Rate in a Benthic Shark. J Biol Rhythms 2022; 37:484-497. [PMID: 35822624 DOI: 10.1177/07487304221107843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Biological rhythms that are mediated by exogenous factors, such as light and temperature, drive the physiology of organisms and affect processes ranging from cellular to population levels. For elasmobranchs (i.e. sharks, rays, and skates), studies documenting diel activity and movement patterns indicate that many species are crepuscular or nocturnal in nature. However, few studies have investigated the rhythmicity of elasmobranch physiology to understand the mechanisms underpinning these distinct patterns. Here, we assess diel patterns of metabolic rates in a small meso-predator, the epaulette shark (Hemiscyllium ocellatum), across ecologically relevant temperatures and upon acutely removing photoperiod cues. This species possibly demonstrates behavioral sleep during daytime hours, which is supported herein by low metabolic rates during the day and a 1.7-fold increase in metabolic rates at night. From spring to summer seasons, where average average water temperature temperatures for this species range 24.5 to 28.5 °C, time of day, and not temperature, had the strongest influence on metabolic rate. These results indicate that this species, and perhaps other similar species from tropical and coastal environments, may have physiological mechanisms in place to maintain metabolic rate on a seasonal time scale regardless of temperature fluctuations that are relevant to their native habitats.
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Affiliation(s)
- Carolyn R Wheeler
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.,School for the Environment, The University of Massachusetts Boston, Boston, Massachusetts
| | - Jeff Kneebone
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, Massachusetts
| | - Dennis Heinrich
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Jan M Strugnell
- Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, Australia.,Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Victoria, Australia
| | - John W Mandelman
- School for the Environment, The University of Massachusetts Boston, Boston, Massachusetts.,Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, Massachusetts
| | - Jodie L Rummer
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.,College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
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Abstract
Energy derived from food is a precious resource to animals. Those finite calories are often well-earned through exhaustive foraging effort, which can dominate waking hours, to support physiological processes (e.g. body maintenance and growth) and ecological necessities (e.g. predator avoidance and courting) that are pertinent to the production of progeny. So, it is unsurprising to find that animals have evolved strategies to guard against the gratuitous waste of hard-won caloric energy. Yet, it remains surprising to find such diversity, and elegant creativity, in those solutions. Brief examples of energy-saving innovation could include the very shape of animals and how they move, from streamlined swimming sharks to skyward-soaring seabirds; or the evolutionary appearance of various states of dormancy, such as endothermic animals sacrificing high body temperature through modest (torpor) or severe (hibernation) curtailments to metabolic heat production. Another reversibly dormant state with energetic benefits is sleep.
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Affiliation(s)
- John A Lesku
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia.
| | - Markus H Schmidt
- Department of Neurology, Center for Experimental Neurology, Bern University Hospital (Inselspital), Bern, Switzerland; Ohio Sleep Medicine Institute, Dublin, OH, USA.
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10
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Kelly ML, Collins SP, Lesku JA, Hemmi JM, Collin SP, Radford CA. Energy conservation characterizes sleep in sharks. Biol Lett 2022; 18:20210259. [PMID: 35259943 PMCID: PMC8915397 DOI: 10.1098/rsbl.2021.0259] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Sharks represent the earliest group of jawed vertebrates and as such, they may provide original insight for understanding the evolution of sleep in more derived animals. Unfortunately, beyond a single behavioural investigation, very little is known about sleep in these ancient predators. As such, recordings of physiological indicators of sleep in sharks have never been reported. Reduced energy expenditure arising from sustained restfulness and lowered metabolic rate during sleep have given rise to the hypothesis that sleep plays an important role for energy conservation. To determine whether this idea applies also to sharks, we compared metabolic rates of draughtsboard sharks (Cephaloscyllium isabellum) during periods ostensibly thought to be sleep, along with restful and actively swimming sharks across a 24 h period. We also investigated behaviours that often characterize sleep in other animals, including eye closure and postural recumbency, to establish relationships between physiology and behaviour. Overall, lower metabolic rate and a flat body posture reflect sleep in draughtsboard sharks, whereas eye closure is a poorer indication of sleep. Our results support the idea for the conservation of energy as a function of sleep in these basal vertebrates.
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Affiliation(s)
- Michael L Kelly
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Selwyn P Collins
- Institute of Marine Science, Leigh Marine Laboratory, The University of Auckland, Auckland, New Zealand
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Jan M Hemmi
- School of Biological Sciences, The University of Western Australia, Perth, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia
| | - Shaun P Collin
- School of Life Sciences, La Trobe University, Melbourne, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia.,Oceans Graduate School, The University of Western Australia, Perth, Australia
| | - Craig A Radford
- Institute of Marine Science, Leigh Marine Laboratory, The University of Auckland, Auckland, New Zealand
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