scholarly journals Aerobic scope does matter in the temperature-size rule but only under optimal conditions

2021 ◽  
Author(s):  
Aleksandra Walczyńska ◽  
Mateusz Sobczyk
Keyword(s):  
Body Size ◽  
Specific Dynamic Action ◽  
Nuclear Size ◽  
Severe Hypoxia ◽  
Aerobic Performance ◽  
Evolutionary Significance ◽  
Optimal Conditions ◽  
Aerobic Scope ◽  
Female Ratio ◽  
Hypoxic Conditions

We united theoretical predictions of the factors responsible for the evolutionary significance of the temperature-size rule (TSR). We assumed that (i) the TSR is a response to temperature-dependent oxic conditions, (ii) body size decrease is a consequence of cell shrinkage in response to hypoxia, (iii) this response enables organisms to maintain a wide scope for aerobic performance, and (iv) it prevents a decrease in fitness. We examined three clones of the rotifer Lecane inermis exposed to three experimental regimes: mild hypoxia, severe hypoxia driven by a too high temperature, and severe hypoxia driven by an inadequate oxygen concentration. We compared the following traits in normoxia- and hypoxia-exposed rotifers: nuclear size (a proxy for cell size), body size, specific dynamic action (SDA, a proxy of aerobic metabolism) and two fitness measures, the population growth rate and eggs/female ratio. The results showed that (i) under mildly hypoxic conditions, our causative reasoning was correct, except that one of the clones decreased in body size without a decrease in nuclear size, and (ii) in more stressful environments, rotifers exhibited clone- and condition-specific responses, which were equally successful in terms of fitness levels. Our results indicate the importance of the rule testing conditions. The important conclusions were that (i) a body size decrease at higher temperatures enabled the maintenance of a wide aerobic scope under clone-specific, thermally optimal conditions, and (ii) this response was not the only option to prevent fitness reduction under hypoxia.

scholarly journals Aerobic scope does matter in temperature-size rule, but only under optimal conditions

2020 ◽  
Author(s):  
Aleksandra Walczyńska ◽  
Anna Maria Labecka ◽  
Mateusz Sobczyk
Keyword(s):  
Body Size ◽  
The Body ◽  
Severe Hypoxia ◽  
Aerobic Performance ◽  
Evolutionary Significance ◽  
Causal Connection ◽  
Optimal Conditions ◽  
Aerobic Scope ◽  
Hypoxic Conditions ◽  
Response To Temperature

AbstractWe united the theoretical predictions on the factors responsible for the occurrence and evolutionary significance of the temperature-size rule. We tested the causal connection among them assuming that (i) the temperature-size rule is the response to temperature-dependent oxygenic conditions, (ii) body size decrease is a consequence of cell shrinkage in response to exposure to hypoxia, (iii) this response enables to keep the wide scope for aerobic performance, and (iv) it prevents the decrease in fitness. We conducted our tests on three clones of the rotifer Lecane inermis with different thermal preferences. These clones were exposed to three experimental regimes: mild hypoxia, severe hypoxia driven by a too high temperature, and severe hypoxia driven by an inadequate oxygen concentration. The results showed that our causative reasoning was generally correct, but only under mildly hypoxic conditions. In more stressful environments, rotifers had clone- and condition-specific responses, which in fact were equally successful in terms of the levels of fitness. Our results join for the first time all factors connecting the cause and effect in the temperature-size rule. They indicate the importance of the conditions under which it should be tested. The most important messages from this study were that (i) a decrease in the body size was one of but not the only option for preventing fitness reduction under hypoxia, and (ii) such a response to higher temperature enabled the maintenance of wide aerobic scope in clone-specific, thermally optimal conditions.

scholarly journals Changes in body temperature influence the scaling of and aerobic scope in mammals

2006 ◽  
Vol 3 (1) ◽  
pp. 100-103 ◽  
Author(s):  
James F Gillooly ◽  
Andrew P Allen
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Size Dependence ◽  
Maximal Activity ◽  
Scaling Exponent ◽  
Temperature Influence ◽  
Aerobic Scope ◽  
Metabolic Scope ◽  
Single Power ◽  
Maximum Metabolic Rate

Debate on the mechanism(s) responsible for the scaling of metabolic rate with body size in mammals has focused on why the maximum metabolic rate ( ) appears to scale more steeply with body size than the basal metabolic rate (BMR). Consequently, metabolic scope, defined as /BMR, systematically increases with body size. These observations have led some to suggest that and BMR are controlled by fundamentally different processes, and to discount the generality of models that predict a single power-law scaling exponent for the size dependence of the metabolic rate. We present a model that predicts a steeper size dependence for than BMR based on the observation that changes in muscle temperature from rest to maximal activity are greater in larger mammals. Empirical data support the model's prediction. This model thus provides a potential theoretical and mechanistic link between BMR and .

THE WATER AND ELECTROLYTE METABOLISM OF RAT DIAPHRAGM IN VITRO

1956 ◽  
Vol 34 (1) ◽  
pp. 1069-1083 ◽  
Author(s):  
R. H. Rixon ◽  
J. A. F. Stevenson
Keyword(s):  
Intracellular Water ◽  
Diaphragm Muscle ◽  
Optimal Conditions ◽  
Rat Diaphragm ◽  
Concentration Gradients ◽  
Hypoxic Conditions ◽  
Diaphragm In Vitro ◽  
Sodium And Potassium

The distribution of water and of sodium and potassium between the cell and synthetic environments has been studied in rat diaphragm muscle. It has been found that: (1) the amount of intracellular water is markedly increased at 0 °C. in oxygen and at 37 °C. in nitrogen compared to that of tissue at 37 °C. in oxygen, in media up to 0.75 osmolar; (2) optimal conditions of temperature and oxygen are necessary to prevent or reduce the uptake of water; (3) swelling at reduced temperatures and under hypoxic conditions is related to the oxygen uptake; (4) the loss of tissue solids during incubation does not have any significant effect on the calculation of the total tissue and intracellular water; (5) the concentration of total sodium and potassium in the tissue, in vivo and in vitro at optimal conditions is slightly in excess of that in the plasma water or incubating medium—this is believed not to represent an active hypertonicity; (6) concomitant with the uptake of water there are marked redistributions of sodium and potassium, the gain of sodium being greater than the loss of potassium. It is concluded that the swelling of tissue cells under conditions that inhibit oxidative metabolism is primarily due to the redistribution of electrolytes and that the natural distribution of water in muscle is determined by active maintenance of the concentration gradients of sodium and potassium across the cell membrane.

scholarly journals Simulated maternal stress reduces offspring aerobic swimming performance in Pacific salmon

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Amanda I Banet ◽  
Stephen J Healy ◽  
Erika J Eliason ◽  
Edward A Roualdes ◽  
David A Patterson ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Citrate Synthase ◽  
Maternal Stress ◽  
Pacific Salmon ◽  
Swimming Performance ◽  
Haemoglobin Concentration ◽  
Aerobic Performance ◽  
Aerobic Scope ◽  
Lactate Dehydrogenase Activity ◽  
Treatment Groups

Abstract Pacific salmon routinely encounter stressors during their upriver spawning migration, which have the potential to influence offspring through hormonally-mediated maternal effects. To disentangle genetic vs. hormonal effects on offspring swimming performance, we collected gametes from three species of Pacific salmon (Chinook, pink and sockeye) at the end of migration and exposed a subset of eggs from each female to cortisol baths to simulate high levels of maternal stress. Fertilised eggs were reared to fry and put through a series of aerobic swim trials. Results show that exposure to cortisol early in development reduces maximum oxygen consumption while swimming, and decreases aerobic scope in all three species. Resting oxygen consumption did not differ between cortisol and control treatment groups. We also examined several metrics that could influence aerobic performance, and found no differences between treatment groups in haematocrit%, haemoglobin concentration, heart mass, citrate synthase activity or lactate dehydrogenase activity. Though it was not the focus of this study, an interesting discovery was that pink salmon had a higher MO2max and aerobic scope relative to the other species, which was supported by a greater haematocrit, haemoglobin, a larger heart and higher CS activity. Some management and conservation practices for Pacific salmon focus efforts primarily on facilitating adult spawning. However, if deleterious effects of maternal stress acquired prior to spawning persist into the next generation, consideration will need to be given to sub-lethal effects that could be imparted onto offspring from maternal stress.

scholarly journals Effects of Severe Hypoxia on Bone Marrow Mesenchymal Stem Cells Differentiation Potential

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Claudia Cicione ◽  
Emma Muiños-López ◽  
Tamara Hermida-Gómez ◽  
Isaac Fuentes-Boquete ◽  
Silvia Díaz-Prado ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Molecular Mechanisms ◽  
Control Point ◽  
Severe Hypoxia ◽  
Marker Genes ◽  
Differentiation Potential ◽  
Differentiation Capacity ◽  
Hypoxic Conditions

Background. The interests in mesenchymal stem cells (MSCs) and their application in cell therapy have resulted in a better understanding of the basic biology of these cells. Recently hypoxia has been indicated as crucial for complete chondrogenesis. We aimed at analyzing bone marrow MSCs (BM-MSCs) differentiation capacity under normoxic and severe hypoxic culture conditions.Methods. MSCs were characterized by flow cytometry and differentiated towards adipocytes, osteoblasts, and chondrocytes under normoxic or severe hypoxic conditions. The differentiations were confirmed comparing each treated point with a control point made of cells grown in DMEM and fetal bovine serum (FBS).Results. BM-MSCs from the donors displayed only few phenotypical differences in surface antigens expressions. Analyzing marker genes expression levels of the treated cells compared to their control point for each lineage showed a good differentiation in normoxic conditions and the absence of this differentiation capacity in severe hypoxic cultures.Conclusions. In our experimental conditions, severe hypoxia affects thein vitrodifferentiation potential of BM-MSCs. Adipogenic, osteogenic, and chondrogenic differentiations are absent in severe hypoxic conditions. Our work underlines that severe hypoxia slows cell differentiation by means of molecular mechanisms since a decrease in the expression of adipocyte-, osteoblast-, and chondrocyte-specific genes was observed.

Relation of body size to nuclear size in Stentor caeruleus

1929 ◽  
Vol 54 (3) ◽  
pp. 473-483 ◽  
Author(s):  
Lenoir H. Burnside
Keyword(s):  
Body Size ◽  
Nuclear Size

scholarly journals The mechanistic basis of aerobic performance variation in red junglefowl

2000 ◽  
Vol 203 (13) ◽  
pp. 2053-2064 ◽  
Author(s):  
K.A. Hammond ◽  
M.A. Chappell ◽  
R.A. Cardullo ◽  
R. Lin ◽  
T.S. Johnsen
Keyword(s):  
Aerobic Capacity ◽  
Citrate Synthase ◽  
Social Rank ◽  
Reproductive Organs ◽  
Male Dominance ◽  
Aerobic Performance ◽  
Aerobic Scope ◽  
Leg Muscles ◽  
Red Junglefowl ◽  
Mechanistic Basis

We examined aerobic performance, organ and muscle mass and enzymatic activity in red junglefowl (Gallus gallus). We tested three models of performance limitation (central limits, peripheral limits, symmorphosis) and explored relationships between basal metabolic rate (BMR), aerobic capacity (V (O2max)) and social rank. Males had a lower BMR, a higher V (O2max) and a greater aerobic scope than females. Females possessed larger peritoneal and reproductive organs, while males had larger hearts, lungs and leg muscles. In females, BMR was correlated with spleen mass and V (O2max) was correlated with hematocrit and large intestine mass. Male BMR was correlated with intestinal tract and lung mass, and V (O2max) was correlated with heart and pectoralis mass. Male citrate synthase activity averaged 57 % higher than that of females and was correlated with V (O2max) (this correlation was not significant in females). Female social status was not correlated with any variable, but male dominance was associated with higher aerobic scope, larger heart and lungs, smaller peritoneal organs and greater leg citrate synthase activity. We conclude that aerobic capacity is controlled by system-wide limitations (symmorphosis) in males, while in females it is controlled by central organs. In neither sex is elevated aerobic capacity associated with increased maintenance costs.

scholarly journals The aerobic scope protection hypothesis: a mechanism explaining reduced growth of ectotherms in warming environments?

2020 ◽  
Author(s):  
Fredrik Jutfelt ◽  
Tommy Norin ◽  
Eirik R Åsheim ◽  
Lauren E Rowsey ◽  
Anna H Andreassen ◽  
...  
Keyword(s):  
Growth Rate ◽  
Oxygen Consumption ◽  
Oxygen Consumption Rate ◽  
Consumption Rate ◽  
Mechanistic Explanation ◽  
Specific Dynamic Action ◽  
Peak Oxygen Consumption ◽  
Aerobic Scope ◽  
Rate Reduction ◽  
The Difference

Temperature has a dramatic effect on the physiology of ectothermic animals, impacting most of their biology. When temperatures increase above optimal for an animal, their growth rate tends to decrease. The mechanism behind this growth rate reduction is unknown. Here, we suggest the aerobic scope protection hypothesis as a mechanistic explanation for the reduction in growth. After a meal, metabolic rate, and hence oxygen consumption rate, transiently increases in a process called specific dynamic action (SDA). At warmer temperatures, the SDA response becomes temporally compressed, leading to a higher peak oxygen consumption rate. This peak in oxygen consumption rate takes up much of the animal’s aerobic scope (the difference between maximum and resting rates of oxygen consumption), leaving little residual aerobic scope for other functions. We propose that animals will actively protect their postprandial residual aerobic scope by reducing meal sizes in order to regulate the peak SDA response. This hypothesis is consistent with the published literature and we suggest further predictions to test it.

Factorial scopes of cardio-metabolic variables remain constant with changes in body temperature in the varanid lizard, Varanus rosenbergi

2005 ◽  
Vol 288 (4) ◽  
pp. R992-R997 ◽  
Author(s):  
T. D. Clark ◽  
T. Wang ◽  
P. J. Butler ◽  
P. B. Frappell
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Oxygen Affinity ◽  
Aerobic Performance ◽  
Specific Rate ◽  
Aerobic Scope ◽  
Thermal Dependence ◽  
Hemoglobin Oxygen Affinity ◽  
Rate Of Oxygen Consumption ◽  
Metabolic Performance

The majority of information concerning the cardio-metabolic performance of varanids during exercise is limited to a few species at their preferred body temperature (Tb) even though, being ectotherms, varanids naturally experience rather large changes in Tb. Although it is well established that absolute aerobic scope declines with decreasing Tb, it is not known whether changes in cardiac output (V̇b) and/or tissue oxygen extraction, (CaO2 − Cv�[Formula: see text]), are in proportion to the rate of oxygen consumption (V̇o2). To test this, we studied six Rosenberg's goannas ( Varanus rosenbergi) while at rest and while maximally exercising on a treadmill both at 25 and 36°C. During maximum exercise both at 25 and 36°C, mass-specific rate of oxygen consumption (V̇o2kg) increased with an absolute scope of 8.5 ml min−1 kg−1 and 15.7 ml min−1 kg−1, respectively. Interestingly, the factorial aerobic scope was temperature-independent and remained at 7.0 which, at each Tb, was primarily the result of an increase in V̇bkg, governed by approximate twofold increases both in heart rate ( fH) and cardiac stroke volume (VSkg). Both at 25°C and 36°C, the increase in V̇bkg alone was not sufficient to provide all of the additional oxygen required to attain maximal V̇o2kg, as indicated by a decrease in the blood convection requirement V̇bkg/V̇o2kg; hence, there was a compensatory twofold increase in (CaO2 − [Formula: see text]). Although associated with an increase in hemoglobin-oxygen affinity, a decrease in Tb did not impair unloading of oxygen at the tissues and act to reduce (CaO2 − Cv�[Formula: see text]); both CaO2 and Cv�[Formula: see text] were maintained across Tb. The change in V̇o2kg with Tb, therefore, is solely reliant on the thermal dependence of V̇bkg. Maintaining a high factorial aerobic scope across a range of Tb confers an advantage in that cooler animals can achieve higher absolute aerobic scopes and presumably improved aerobic performance than would otherwise be achievable.

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