scholarly journals Plasticity of muscle function in a thermoregulating ectotherm (Crocodylus porosus): biomechanics and metabolism

2008 ◽  
Vol 294 (3) ◽  
pp. R1024-R1032 ◽  
Author(s):  
Frank Seebacher ◽  
Rob S. James
Keyword(s):  
Atpase Activity ◽  
Cold Acclimation ◽  
Muscle Function ◽  
Thermal Sensitivity ◽  
Thermal Acclimation ◽  
Myofibrillar Atpase ◽  
Body Temperatures ◽  
Thermal Environments ◽  
Crocodylus Porosus ◽  
Work Loop

Thermoregulation and thermal sensitivity of performance are thought to have coevolved so that performance is optimized within the selected body temperature range. However, locomotor performance in thermoregulating crocodiles ( Crocodylus porosus) is plastic and maxima shift to different selected body temperatures in different thermal environments. Here we test the hypothesis that muscle metabolic and biomechanical parameters are optimized at the body temperatures selected in different thermal environments. Hence, we related indices of anaerobic (lactate dehydrogenase) and aerobic (cytochrome c oxidase) metabolic capacities and myofibrillar ATPase activity to the biomechanics of isometric and work loop caudofemoralis muscle function. Maximal isometric stress (force per muscle cross-sectional area) did not change with thermal acclimation, but muscle work loop power output increased with cold acclimation as a result of shorter activation and relaxation times. The thermal sensitivity of myofibrillar ATPase activity decreased with cold acclimation in caudofemoralis muscle. Neither aerobic nor anaerobic metabolic capacities were directly linked to changes in muscle performance during thermal acclimation, although there was a negative relationship between anaerobic capacity and isometric twitch stress in cold-acclimated animals. We conclude that by combining thermoregulation with plasticity in biomechanical function, crocodiles maximize performance in environments with highly variable thermal properties.

Thermal sensitivity of contractile function in chain pickerel, Esox niger

1985 ◽  
Vol 63 (4) ◽  
pp. 811-816 ◽  
Author(s):  
Bruce D. Sidell ◽  
Ian A. Johnston
Keyword(s):  
Atpase Activity ◽  
White Muscle ◽  
Contractile Function ◽  
Thermal Sensitivity ◽  
Muscle Fibers ◽  
Temperature Sensitive ◽  
Myofibrillar Atpase ◽  
Thermal Dependence ◽  
Tension Development ◽  
Myofibrillar Atpase Activity

Maximum catalytic activity and thermal sensitivity of Mg2+–Ca2+ activated myofibrillar ATPase from either red or white muscle tissue of chain pickerel is unaffected by 4–6 weeks acclimation to temperatures of 5 or 25 °C. Arrhenius plots of myofibrillar ATPase activity from red muscle are linear over the entire range of assay temperatures (2–32 °C; Q10 = 3.3). Similar plots of white muscle ATPase activity show a pronounced discontinuity at approximately 10 °C and a much greater thermal sensitivity below this temperature (Q10 = 11.2) than above it (Q10 = 2.2). Thermal dependence of myofibrillar ATPase activity from white muscle does not accurately predict the effect of temperature upon contraction velocities of isolated white muscle fibers. Contraction velocity of single chemically skinned white muscle fibers was sevenfold less temperature sensitive than ATPase activity below the 10 °C transition and 1.6-fold less temperature sensitive above this temperature (Q10 (0–27 °C) = 1.6). Maximum Ca2+-activated tension development was particularly temperature independent (Q10 = 1.2), ranging from 14 ± 1.6 N/cm2 at 5 °C to 20.9 ± 2.1 N/cm2 at 25 °C. Power output chain pickerel muscle, a product of these two parameters (force × velocity), should therefore show a relatively low thermal dependence (Q10 < 2) over the normal range of habitat temperatures.

Plasticity of fish muscle mitochondria with thermal acclimation

1996 ◽  
Vol 199 (6) ◽  
pp. 1311-1317 ◽  
Author(s):  
H Guderley ◽  
I A Johnston
Keyword(s):  
Cold Acclimation ◽  
Thermal Sensitivity ◽  
Fish Muscle ◽  
Oxidative Capacity ◽  
Thermal Acclimation ◽  
Palmitoyl Carnitine ◽  
Pyruvate Oxidation ◽  
Myoxocephalus Scorpius ◽  
Q10 Values ◽  
The Impact

Short-horned sculpin Myoxocephalus scorpius were acclimated to 5 and 15 &deg;C to evaluate the impact of thermal acclimation upon maximal rates of substrate oxidation by mitochondria and upon the thermal sensitivity of their ADP affinity. Cold acclimation virtually doubled maximal rates of pyruvate oxidation at all experimental temperatures (2.5, 7.5, 12.5 and 20 &deg;C). Rates of palmitoyl carnitine oxidation were also enhanced by cold acclimation, but to a lesser degree. At their respective acclimation temperatures, the mitochondria attained similar rates of pyruvate oxidation. For warm-acclimated sculpin, the Q10 values for mitochondrial pyruvate and palmitoyl carnitine oxidation were higher between 2.5 and 7.5 &deg;C than between 7.5 and 12.5 &deg;C or between 12.5 and 20 &deg;C. In contrast, for cold-acclimated fish, the Q10 values did not differ over these thermal ranges. The Arrhenius activation energy for pyruvate oxidation was reduced by cold acclimation (from 70 to 55 kJ mol-1), whereas that for palmitoyl carnitine oxidation was unchanged (approximately 75 kJ mol-1). Cold acclimation did not alter the ADP affinity of mitochondria at low temperatures but markedly increased the apparent Km for ADP (Km,app) at 12.5 and 20 &deg;C. At the acclimation temperatures, mitochondrial ADP Km,app values did not differ. The loss of ADP affinity at higher temperatures may represent a cost of the enhanced maximal oxidative capacity achieved during cold acclimation.

Spatiotemporal variation in thermal niches suggests lability rather than conservatism of thermal physiology along an environmental gradient

2019 ◽  
Author(s):  
Anthony L Gilbert ◽  
Donald B Miles
Keyword(s):  
Environmental Gradients ◽  
Thermal Sensitivity ◽  
Population Level ◽  
Elevational Gradient ◽  
Population Variation ◽  
Model Systems ◽  
Body Temperatures ◽  
Thermal Physiology ◽  
Thermal Environments ◽  
Tree Lizard

Abstract Temperature variation throughout a species range can be extensive and exert divergent spatiotemporal patterns of selection. The estimation of phenotypic differences of populations along environmental gradients provides information regarding population-level responses to changing environments and evolutionary lability in climate-relevant traits. However, few studies have found physiological differentiation across environmental gradients attributable to behavioural thermoregulation buffering physiological evolution. Here, we compared thermal sensitivity of physiological performance among three populations of the ornate tree lizard (Urosaurus ornatus) along a 1100 m elevational gradient in southeastern Arizona across years in order to determine whether spatial differences in thermal environments are capable of driving local physiological differentiation. Lizards exhibited significant population-level differences in thermal physiology. The thermal traits of lizards at low elevations included warmer body temperatures and higher preferred and critical thermal temperatures. In contrast, lizards at higher elevations had cooler body temperatures and lower preferred and critical thermal temperatures. Populations also exhibited differences in the optimal temperature for performance and thermal performance breadth. The direction of population variation was consistent across years. Environmental gradients can provide model systems for studying the evolution of thermal physiology, and our study is one of the first to suggest that population differentiation in thermal physiology could be more prominent than previously thought.

scholarly journals Thermal acclimation alters the roles of Na+/K+-ATPase activity in a tissue-specific manner in Drosophila melanogaster

2020 ◽  
Author(s):  
Alexandra Cheslock ◽  
Mads Kuhlmann Andersen ◽  
Heath A. MacMillan
Keyword(s):  
Drosophila Melanogaster ◽  
Membrane Potential ◽  
Atpase Activity ◽  
Cold Acclimation ◽  
Muscle Cell ◽  
Thermal Sensitivity ◽  
Chill Coma ◽  
Specific Manner ◽  
Pump Activity ◽  
The Brain

AbstractInsects, like the model species Drosophila melanogaster, lose neuromuscular function and enter a state of paralysis (chill coma) at a population- and species-specific low temperature threshold that is decreased by cold acclimation. Entry into this coma is related to a spreading depolarization in the central nervous system, while recovery involves restoration of electrochemical gradients across muscle cell membranes. The Na+/K+-ATPase helps maintain ion balance and membrane potential in both the brain and hemolymph (surrounding muscles), and changes in thermal tolerance traits have therefore been hypothesized to be closely linked to variation in the expression and/or activity of this pump in multiple tissues. Here, we tested this hypothesis by measuring activity and thermal sensitivity of the Na+/K+-ATPase at the tagma-specific level (head, thorax and abdomen) in warm-(25°C) and cold-acclimated (15°C) flies by Na+/K+-ATPase activity at 15, 20, and 25°C. We relate differences in pump activity to differences in chill coma temperature, spreading depolarization temperature, and thermal dependence of muscle cell polarization. Differences in pump activity and thermal sensitivity induced by cold acclimation varied in a tissue-specific manner: While cold-acclimated flies had decreased thermal sensitivity of Na+/K+-ATPase that maintains activity at low temperatures in the thorax (mainly muscle), activity instead decreased in the heads (mainly brain). We argue that these changes may assist in maintenance of K+ homeostasis and membrane potential across muscle membranes and discuss how reduced Na+/K+-ATPase activity in the brain may counterintuitively help insects delay coma onset in the cold.

scholarly journals Implementing a clinical assessment protocol for sensory and skeletal function in diabetic neuropathy patients at a university hospital in Brazil

2005 ◽  
Vol 123 (5) ◽  
pp. 229-233 ◽  
Author(s):  
Isabel de Camargo Neves Sacco ◽  
Silvia Maria Amado João ◽  
Denise Alignani ◽  
Daniela Kinoshita Ota ◽  
Cristina Dallemole Sartor ◽  
...  
Keyword(s):  
Diabetic Neuropathy ◽  
Range Of Motion ◽  
Muscle Function ◽  
Thermal Sensitivity ◽  
Preliminary Investigation ◽  
Lower Limbs ◽  
Triceps Surae ◽  
University Hospital ◽  
Tactile Sensitivity ◽  
Assessment Protocol

CONTEXT AND OBJECTIVE: Physiotherapy can contribute towards recovering or preventing physical and sensory alterations in diabetic neuropathy patients. Our objective was to create and apply a protocol for functional assessment of diabetic neuropathy patients' lower limbs, to guide future physiotherapy. DESIGN AND SETTING: Clinical study at the University Hospital and teaching/research center of Universidade de São Paulo. METHODS: An intentional sample of diabetic neuropathy patients was utilized. The protocol was divided into: (1) preliminary investigation with identification of relevant clinical diabetes and neuropathy characteristics; (2) thermal, tactile and proprioceptive sensitivity tests on the feet; (3) evaluations of muscle function, range of motion, lower limb function, foot anthropometry. RESULTS: The patients' mean age was 57 years, and they had had the diagnosis for 13 years on average. Distal numbness and tingling/prickling were present in 62% and 67%, respectively. There were tactile sensitivity alterations above the heel in 50%, with thermal sensitivity in 40% to 60%. The worst muscle function test responses were at the triceps surae and foot intrinsic muscles. Longitudinal plantar arches were lowered in 50%. Decreased thermal and tactile sensitivity of the heels was found. There was a general reduction in range of motion. CONCLUSIONS: The results provided detailed characterization of the patients. This protocol may be easily applied in healthcare services, since it requires little equipment, at low cost, and it is well understood by patients.

scholarly journals Ca2+-ATPase activity and Ca2+ uptake by sarcoplasmic reticulum in fish heart: effects of thermal acclimation.

1998 ◽  
Vol 201 (4) ◽  
pp. 525-532 ◽  
Author(s):  
E Aho ◽  
M Vornanen
Keyword(s):  
Atpase Activity ◽  
Uptake Rate ◽  
Teleost Fish ◽  
Crucian Carp ◽  
Thermal Acclimation ◽  
The Body ◽  
Newborn Rat ◽  
Fish Heart ◽  
Adult Rat ◽  
Uptake Velocity

This study was designed to compare the activities of sarcoplasmic (SR) Ca2+-ATPase and Ca2+ uptake in fish and mammalian hearts and to determine whether thermal acclimation has any effect on the function of the cardiac SR in fish. To this end, we measured thapsigargin-sensitive Ca2+-ATPase activity and thapsigargin-inhibitable Ca2+ uptake velocity in crude cardiac homogenates of newborn and adult rats and of two teleost fish (crucian carp and rainbow trout) acclimated to low (4 degrees C) and high (17 degrees C and 24 degrees C for trout and carp, respectively) ambient temperatures. The TG-sensitive Ca2+-ATPase activity was highest in adult rat, and the corresponding activities of cold-acclimated trout, warm-acclimated trout, warm-acclimated carp, cold-acclimated carp and newborn rat were 76, 58, 43, 28 and 23 %, respectively, of that of the adult rat at 25 degrees C. SR Ca2+ uptake velocity, measured using Fura-2 at room temperature (approximately 22 degrees C), was highest in cold-acclimated trout, and the values for adult rat, warm-acclimated trout, newborn rat, warm-acclimated carp and cold-acclimated carp were 93, 56, 24, 21 and 14 % of the uptake velocity of cold-acclimated trout, respectively. When corrected to the body temperature of the animal, the relative rates of SR Ca2+ uptake were 100, 26, 19, 18, 11 and 2 % for adult rat, newborn rat, cold-acclimated trout, warm-acclimated trout, warm-acclimated carp and cold-acclimated carp, respectively. These findings show that SR Ca2+ uptake is slower in fish than in mammalian hearts and that marked species-specific differences exist among teleost fish in this respect. Furthermore, acclimation to cold increases the Ca2+ uptake rate of trout cardiac SR (complete thermal compensation) but decreases the SR Ca2+ uptake rate of crucian carp heart. This difference in acclimation response probably reflects the different activity patterns of the two species in their natural habitat during the cold season.

scholarly journals Phytoplankton thermal responses adapt in the absence of hard thermodynamic constraints

2018 ◽  
Author(s):  
Dimitrios - Georgios Kontopoulos ◽  
Erik van Sebille ◽  
Michael Lange ◽  
Gabriel Yvon-Durocher ◽  
Timothy G. Barraclough ◽  
...  
Keyword(s):  
Thermal Performance ◽  
Thermal Sensitivity ◽  
Meta Analysis ◽  
Habitat Type ◽  
Performance Curve ◽  
Thermal Environments ◽  
Thermal Performance Curve ◽  
Performance Curves ◽  
Minor Influence ◽  
A Minor

AbstractTo better predict how populations and communities respond to climatic temperature variation, it is necessary to understand how the shape of the response of fitness-related traits to temperature evolves (the thermal performance curve). Currently, there is disagreement about the extent to which the evolution of thermal performance curves is constrained. One school of thought has argued for the prevalence of thermodynamic constraints through enzyme kinetics, whereas another argues that adaptation can—at least partly—overcome such constraints. To shed further light on this debate, we perform a phylogenetic meta-analysis of the thermal performance curves of growth rate of phytoplankton—a globally important functional group—, controlling for environmental effects (habitat type and thermal regime). We find that thermodynamic constraints have a minor influence on the shape of the curve. In particular, we detect a very weak increase of maximum performance with the temperature at which the curve peaks, suggesting a weak “hotter-is-better” constraint. Also, instead of a constant thermal sensitivity of growth across species, as might be expected from strong constraints, we find that all aspects of the thermal performance curve evolve along the phylogeny. Our results suggest that phytoplankton thermal performance curves adapt to thermal environments largely in the absence of hard thermodynamic constraints.

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