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Auteur Hermes-Lima, M.; Moreira, D.C.; Rivera-Ingraham, G.A.; Giraud-Billoud, M.; Genaro-Mattos, T.C.; Campos, É.G. url  doi
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  Titre Preparation for oxidative stress under hypoxia and metabolic depression: Revisiting the proposal two decades later Type Article scientifique
  Année 2015 Publication Revue Abrégée Free Radical Biology and Medicine  
  Volume 89 Numéro Pages 1122-1143  
  Mots-Clés Anoxia; Dehydration; Estivation; Freeze tolerance; Hypoxia tolerance; Ischemia  
  Résumé Organisms that tolerate wide variations in oxygen availability, especially to hypoxia, usually face harsh environmental conditions during their lives. Such conditions include, for example, lack of food and/or water, low or high temperatures, and reduced oxygen availability. In contrast to an expected strong suppression of protein synthesis, a great number of these animals present increased levels of antioxidant defenses during oxygen deprivation. These observations have puzzled researchers for more than 20 years. Initially, two predominant ideas seemed to be irreconcilable: on one hand, hypoxia would decrease reactive oxygen species (ROS) production, while on the other the induction of antioxidant enzymes would require the overproduction of ROS. This induction of antioxidant enzymes during hypoxia was viewed as a way to prepare animals for oxidative damage that may happen ultimately during reoxygenation. The term “preparation for oxidative stress” (POS) was coined in 1998 based on such premise. However, there are many cases of increased oxidative damage in several hypoxia-tolerant organisms under hypoxia. In addition, over the years, the idea of an assured decrease in ROS formation under hypoxia was challenged. Instead, several findings indicate that the production of ROS actually increases in response to hypoxia. Recently, it became possible to provide a comprehensive explanation for the induction of antioxidant enzymes under hypoxia. The supporting evidence and the limitations of the POS idea are extensively explored in this review as we discuss results from research on estivation and situations of low oxygen stress, such as hypoxia, freezing exposure, severe dehydration, and air exposure of water-breathing animals. We propose that, under some level of oxygen deprivation, ROS are overproduced and induce changes leading to hypoxic biochemical responses. These responses would occur mainly through the activation of specific transcription factors (FoxO, Nrf2, HIF-1, NF-κB, and p53) and post translational mechanisms, both mechanisms leading to enhanced antioxidant defenses. Moreover, reactive nitrogen species are candidate modulators of ROS generation in this scenario. We conclude by drawing out the future perspectives in this field of research, and how advances in the knowledge of the mechanisms involved in the POS strategy will offer new and innovative study scenarios of biological and physiological cellular responses to environmental stress.  
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  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0891-5849 ISBN Médium  
  Région (up) Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ alain.herve @ collection 1476  
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Auteur Blasco, F.R.; Esbaugh, A.J.; Killen, S.S.; Rantin, F.T.; Taylor, E.W.; McKenzie, D.J. doi  openurl
  Titre Using aerobic exercise to evaluate sub-lethal tolerance of acute warming in fishes Type Article scientifique
  Année 2020 Publication Revue Abrégée J. Exp. Biol.  
  Volume 223 Numéro 9 Pages jeb218602  
  Mots-Clés capacity; climate-change; CTmax; hypoxia tolerance; marine fishes; Oreochromis niloticus; oxygen-tensions; performance; Piaractus mesopotamicus; scope; sea bass; temperature; thermal tolerance  
  Résumé We investigated whether fatigue from sustained aerobic swimming provides a sub-lethal endpoint to define tolerance of acute warming in fishes, as an alternative to loss of equilibrium (LOE) during a critical thermal maximum (CTmax) protocol. Two species were studied, Nile tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus). Each fish underwent an incremental swim test to determine gait transition speed (U-GT), where it first engaged the unsteady anaerobic swimming mode that preceded fatigue. After suitable recovery, each fish was exercised at 85% of their own U-GT and warmed 1 degrees C every 30 min, to identify the temperature at which they fatigued, denoted as CTswim. Fish were also submitted to a standard CTmax, warming at the same rate as CTswim, under static conditions until LOE. All individuals fatigued in CTswim, at a mean temperature approximately 2 degrees C lower than their CTmax. Therefore, if exposed to acute warming in the wild, the ability to perform aerobic metabolic work would be constrained at temperatures significantly below those that directly threatened survival. The collapse in performance at CTswim was preceded by a gait transition qualitatively indistinguishable from that during the incremental swim test. This suggests that fatigue in CTswim was linked to an inability to meet the tissue oxygen demands of exercise plus warming. This is consistent with the oxygen and capacity limited thermal tolerance (OCLTT) hypothesis, regarding the mechanism underlying tolerance of warming in fishes. Overall, fatigue at CTswim provides an ecologically relevant sub-lethal threshold that is more sensitive to extreme events than LOE at CTmax.  
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  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0022-0949 ISBN Médium  
  Région (up) Expédition Conférence  
  Notes WOS:000541842300012 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2817  
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Auteur Alfonso, S.; Sadoul, B.; Cousin, X.; Begout, M.-L. doi  openurl
  Titre Spatial distribution and activity patterns as welfare indicators in response to water quality changes in European sea bass, Dicentrarchus labrax Type Article scientifique
  Année 2020 Publication Revue Abrégée Appl. Anim. Behav. Sci.  
  Volume 226 Numéro Pages Unsp-104974  
  Mots-Clés ammonia toxicity; atlantic salmon; avoidance-behavior; behavioral-responses; Behaviour; current issues; Fish; hyperoxia; hypoxia tolerance; marine fish; rainbow-trout; Stress; stress-response; Water quality; Welfare  
  Résumé In aquaculture, fish are exposed to unavoidable stressors that can be detrimental for their health and welfare. However, welfare in farmed fish can be difficult to assess, and, so far, no standardized test has been universally accepted as a welfare indicator. This work contributes to the establishment of behavioural welfare indicators in a marine teleost in response to different water quality acute stressors. Groups of ten fish were exposed to high Total Ammonia Nitrogen concentration (High TAN, 18 mg.L-1), Hyperoxia (200 % O-2 saturation), Hypoxia (20 % O-2 saturation), or control water quality (100% O-2 saturation and TAN < 2.5 mg.L-1) over 1 hour. Fish were then transferred in a novel environment for a group behaviour test under the same water quality conditions over 2 hours. Videos were recorded to assess thigmotaxis, activity and group cohesion. After this challenge, plasma cortisol concentration was measured in a subsample, while individual behavioural response was measured in the other fish using novel tank diving test. Prior to this study, the novel tank diving test was validated as a behavioural challenge indicative of anxiety state, by using nicotine as anxiolytic drug. Overall, all stress conditions induced a decrease in activity and thigmotaxis and changes in group cohesion while only fish exposed to Hypoxia and High TAN conditions displayed elevated plasma cortisol concentrations. In post-stress condition, activity was still affected but normal behaviour was recovered within the 25 minutes of the test duration. Our work suggests that the activity, thigmotaxis and group cohesion are good behavioural indicators of exposure to degraded water quality, and could be used as standardized measures to assess fish welfare.  
  Adresse  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0168-1591 ISBN Médium  
  Région (up) Expédition Conférence  
  Notes WOS:000531095400002 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2794  
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