Consulta: creatorFacets:"Metcalfe, Neil B."
Registros recuperados: 11
Data/hora: 11/06/2024 03:08:34

The RCR and ATP/O indices can give contradictory messages about mitochondrial efficiency
Provedor de dados: 5
Autores: Salin, Karine; Villasevil, Eugenia M.; Anderson, Graeme J.; Selman, Colin; Chinopoulos, Christos; Metcalfe, Neil B.
Mitochondrial efficiency is typically taken to represent an animal’s capacity to convert its resources into ATP. However, the term mitochondrial efficiency, as currently used in the literature, can be calculated as either the respiratory control ratio, RCR (ratio of mitochondrial respiration supporting ATP synthesis to that required to offset the proton leak) or as the amount of ATP generated per unit of oxygen consumed, ATP/O ratio. The question of how flexibility in mitochondrial energy properties (i.e. in rates of respiration to support ATP synthesis and offset proton leak, and in the rate of ATP synthesis) affects these indices of mitochondrial efficiency has tended to be overlooked. Furthermore, little is known of whether the RCR and ATP/O ratio vary...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00449/56014/57529.pdf

Simultaneous measurement of mitochondrial respiration and ATP production in tissue homogenates and calculation of effective P/O ratios
Provedor de dados: 5
Autores: Salin, Karine; Villasevil, Eugenia M.; Auer, Sonya K.; Anderson, Graeme J.; Selman, Colin; Metcalfe, Neil B.; Chinopoulos, Christos.
The use of tissue homogenate has greatly aided the study of the functioning of mitochondria. However, the amount of ATP produced per oxygen molecule consumed, that is, the effective P/O ratio, has never been measured directly in tissue homogenate. Here we combine and refine existing methods previously used in permeabilized cells and isolated mitochondria to simultaneously measure mitochondrial ATP production (JATP) and oxygen consumption (JO(2)) in tissue homogenate. A major improvement over existing methods is in the control of ATPases that otherwise interfere with the ATP assay: our modified technique facilitates simultaneous measurement of the rates of uncorrected ATP synthesis and of ATP hydrolysis, thus minimizing the amount of tissue and time needed....
Tipo: Text
Palavras-chave: ATPase; Fluorescence; Magnesium green; Oxidative phosphorylation; Oxygraph.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00414/52500/53300.pdf

Using the MitoB method to assess levels of reactive oxygen species in ecological studies of oxidative stress
Provedor de dados: 5
Autores: Salin, Karine; Auer, Sonya K.; Villasevil, Eugenia M.; Anderson, Graeme J.; Cairns, Andrew G.; Mullen, William; Hartley, Richard C.; Metcalfe, Neil B.
In recent years evolutionary ecologists have become increasingly interested in the effects of reactive oxygen species (ROS) on the life-histories of animals. ROS levels have mostly been inferred indirectly due to the limitations of estimating ROS from in vitro methods. However, measuring ROS (hydrogen peroxide, H2O2) content in vivo is now possible using the MitoB probe. Here, we extend and refine the MitoB method to make it suitable for ecological studies of oxidative stress using the brown trout Salmo trutta as model. The MitoB method allows an evaluation of H2O2 levels in living organisms over a timescale from hours to days. The method is flexible with regard to the duration of exposure and initial concentration of the MitoB probe, and there is no...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00413/52494/53297.pdf

Variation in the link between oxygen consumption and ATP production, and its relevance for animal performance
Provedor de dados: 5
Autores: Salin, Karine; Auer, Sonya K.; Rey, Benjamin; Selman, Colin; Metcalfe, Neil B.
It is often assumed that an animal's metabolic rate can be estimated through measuring the whole-organism oxygen consumption rate. However, oxygen consumption alone is unlikely to be a sufficient marker of energy metabolism in many situations. This is due to the inherent variability in the link between oxidation and phosphorylation; that is, the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by mitochondria (P/O ratio). In this article, we describe how the P/O ratio can vary within and among individuals, and in response to a number of environmental parameters, including diet and temperature. As the P/O ratio affects the efficiency of cellular energy production, its variability may have significant consequences for animal...
Tipo: Text
Palavras-chave: Mitochondrial coupling efficiency; Life history; Oxidative stress; Reactive oxygen species; Trade-off; Uncoupling.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00414/52509/53322.pdf

Decreased mitochondrial metabolic requirements in fasting animals carry an oxidative cost
Provedor de dados: 5
Autores: Salin, Karine; Villasevil, Eugenia M.; Anderson, Graeme J.; Auer, Sonya K.; Selman, Colin; Hartley, Richard C.; Mullen, William; Chinopoulos, Christos; Metcalfe, Neil B.
Many animals experience periods of food shortage in their natural environment. It has been hypothesised that the metabolic responses of animals to naturally‐occurring periods of food deprivation may have long‐term negative impacts on their subsequent life‐history. In particular, reductions in energy requirements in response to fasting may help preserve limited resources but potentially come at a cost of increased oxidative stress. However, little is known about this trade‐off since studies of energy metabolism are generally conducted separately from those of oxidative stress. Using a novel approach that combines measurements of mitochondrial function with in vivo levels of hydrogen peroxide (H2O2) in brown trout (Salmo trutta), we show here that fasting...
Tipo: Text
Palavras-chave: High-resolution respirometry; In vivo; Liver atrophy; MitoB probe; Mitochondrial respiratory state.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00449/56022/57540.pdf

Nutrients from salmon parents alter selection pressures on their offspring
Provedor de dados: 5
Autores: Auer, Sonya K.; Anderson, Graeme J.; Mckelvey, Simon; Bassar, Ronald D.; Mclennan, Darryl; Armstrong, John D.; Nislow, Keith H.; Downie, Helen K.; Mckelvey, Lynn; Morgan, Thomas A. J.; Salin, Karine; Orrell, Danielle L.; Gauthey, Alice; Reid, Thomas C.; Metcalfe, Neil B.
Organisms can modify their surrounding environment, but whether these changes are large enough to feed back and alter their evolutionary trajectories is not well understood, particularly in wild populations. Here we show that nutrient pulses from decomposing Atlantic salmon (Salmo salar) parents alter selection pressures on their offspring with important consequences for their phenotypic and genetic diversity. We found a strong survival advantage to larger eggs and faster juvenile metabolic rates in streams lacking carcasses but not in streams containing this parental nutrient input. Differences in selection intensities led to significant phenotypic divergence in these two traits among stream types. Stronger selection in streams with low parental nutrient...
Tipo: Text
Palavras-chave: Eco-evolutionary dynamics; Eco-evolutionary feedbacks; Natural selection; Niche construction; Salmo salar; Selection differential; Selection gradient.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00414/52586/53426.pdf

Individuals exhibit consistent differences in their metabolic rates across changing thermal conditions
Provedor de dados: 5
Autores: Auer, Sonya K.; Salin, Karine; Anderson, Graeme J.; Metcalfe, Neil B.
Metabolic rate has been linked to growth, reproduction, and survival at the individual level and is thought to have far reaching consequences for the ecology and evolution of organisms. However, differences in metabolic rate among individuals must be consistent (i.e. repeatable) over at least some portion of their lifetime in order to predict their longer-term effects on population dynamics and how they will respond to selection. Previous studies demonstrate that metabolic rates are repeatable under constant conditions but potentially less so in more variable environments. We measured the standard (= minimum) metabolic rate, maximum metabolic rate, and aerobic scope (= interval between standard and maximum rates) in juvenile brown trout (Salmo trutta)...
Tipo: Text
Palavras-chave: Aerobic scope; Consistency; Maximum metabolic rate; Standard metabolic rate; Stability; Thermal repeatability.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00414/52585/53425.pdf

Aerobic scope explains individual variation in feeding capacity
Provedor de dados: 5
Autores: Auer, Sonya K.; Salin, Karine; Anderson, Graeme J.; Metcalfe, Neil B.
Links between metabolism and components of fitness such as growth, reproduction and survival can depend on food availability. A high standard metabolic rate (SMR; baseline energy expenditure) or aerobic scope (AS; the difference between an individual's maximum and SMR) is often beneficial when food is abundant or easily accessible but can be less important or even disadvantageous when food levels decline. While the mechanisms underlying these context-dependent associations are not well understood, they suggest that individuals with a higher SMR or AS are better able to take advantage of high food abundance. Here we show that juvenile brown trout (Salmo trutta) with a higher AS were able to consume more food per day relative to individuals with a lower AS....
Tipo: Text
Palavras-chave: Energy metabolism; Fitness; Food intake; Maximum metabolic rate; Salmo trutta; Standard metabolic rate.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00414/52505/53324.pdf

Variation in Metabolic Rate among Individuals Is Related to Tissue-Specific Differences in Mitochondrial Leak Respiration
Provedor de dados: 5
Autores: Salin, Karine; Auer, Sonya K.; Rudolf, Agata M.; Anderson, Graeme J.; Selman, Colin; Metcalfe, Neil B.
Standard metabolic rate (SMR) and maximum metabolic rate (MMR) typically vary two-or threefold among conspecifics, with both traits assumed to significantly impact fitness. However, the underlying mechanisms that determine such intraspecific variation are not well understood. We examined the influence of mitochondrial properties on intraspecific variation in SMR and MMR and hypothesized that if SMR supports the cost of maintaining the metabolic machinery required for MMR, then the mitochondrial properties underlying these traits should be shared. Mitochondrial respiratory capacity (leak and phosphorylating respiration) and mitochondrial content (cytochrome c oxidase activity) were determined in the liver and white muscle of brown trout Salmo trutta of...
Tipo: Text
Palavras-chave: Brown trout; Fish; Liver; Oxygen consumption; White muscle.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00413/52497/53321.pdf

Flexibility in metabolic rate and activity level determines individual variation in overwinter performance
Provedor de dados: 5
Autores: Auer, Sonya K.; Salin, Karine; Anderson, Graeme J.; Metcalfe, Neil B.
Energy stores are essential for the overwinter survival of many temperate and polar animals, but individuals within a species often differ in how quickly they deplete their reserves. These disparities in overwinter performance may be explained by differences in their physiological and behavioral flexibility in response to food scarcity. However, little is known about whether individuals exhibit correlated or independent changes in these traits, and how these phenotypic changes collectively affect their winter energy use. We examined individual flexibility in both standard metabolic rate and activity level in response to food scarcity and their combined consequences for depletion of lipid stores among overwintering brown trout (Salmo trutta). Metabolism and...
Tipo: Text
Palavras-chave: Activity rate; Intraspecific variation; Lipid stores; Metabolic rate; Phenotypic flexibility.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00413/52498/53299.pdf

Oxygen- and capacity-limited thermal tolerance: blurring ecology and physiology
Provedor de dados: 5
Autores: Jutfelt, Fredrik; Norin, Tommy; Ern, Rasmus; Overgaard, Johannes; Wang, Tobias; Mckenzie, David; Lefevre, Sjannie; Nilsson, Goran E.; Metcalfe, Neil B.; Hickey, Anthony J. R.; Brijs, Jeroen; Speers-roesch, Ben; Roche, Dominique G.; Gamperl, A. Kurt; Raby, Graham D.; Morgan, Rachael; Esbaugh, Andrew J.; Grans, Albin; Axelsson, Michael; Ekstrom, Andreas; Sandblom, Erik; Binning, Sandra A.; Hicks, James W.; Seebacher, Frank; Jorgensen, Christian; Killen, Shaun S.; Schulte, Patricia M.; Clark, Timothy D.
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00666/77823/79997.pdf