scholarly journals A proximal–distal difference in bat wing muscle thermal sensitivity parallels a difference in operating temperatures along the wing

2021 ◽  
Vol 288 (1950) ◽  
Author(s):  
Andrea D. Rummel ◽  
Sharon M. Swartz ◽  
Richard L. Marsh
Keyword(s):  
Temperature Sensitivity ◽  
Contractile Function ◽  
Thermal Sensitivity ◽  
Temperature Sensitive ◽  
Thermal Dependence ◽  
Fruit Bat ◽  
Fast Activation ◽  
Bat Wing ◽  
Forearm Muscle ◽  
Muscle Contractile

Flight is a demanding form of locomotion, requiring fast activation and relaxation in wing muscles to produce the necessary wingbeat frequencies. Bats maintain high body temperatures during flight, but their wing muscles cool under typical environmental conditions. Because distal wing muscles are colder during flight than proximal muscles, we hypothesized that they would be less temperature sensitive to compensate for temperature effects, resulting in proximal–distal differences in temperature sensitivity that match differences in muscle operating temperature. We measured contractile rates across temperatures in the proximal pectoralis muscle and an interosseous in the handwing of Carollia perspicillata , a small neotropical fruit bat, and compared their thermal dependence with that of a forearm muscle measured in a previous study. We found that the contractile properties of the pectoralis were significantly more temperature sensitive than those of the distal muscles. This suggests that cooling of the distal wing muscles imposes a selective pressure on muscle contractile function which has led to shifts in temperature sensitivity. This study is the first to demonstrate differences in temperature sensitivity along the length of a single limb in an endotherm and suggests that temperature variation may be underappreciated as a determinant of locomotor performance in endotherms generally.

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.

scholarly journals Understanding thermal sensitivity at the molecular level and developing temperature-based systems using RNA Thermometers

2016 ◽  
Vol 39 (6) ◽  
pp. 3
Author(s):  
Fatih Gul ◽  
Ibrahim Y Orhan ◽  
Furkan S Ceylan ◽  
Nadir B Akdeniz ◽  
H Abdulkadir Karadag
Keyword(s):  
Temperature Sensitivity ◽  
Thermal Sensitivity ◽  
Exothermic Reaction ◽  
Enzymatic Reaction ◽  
Life Forms ◽  
Temperature Sensitive ◽  
Enzymatic Reactions ◽  
Synthetic Solution ◽  
Transcriptional Process ◽  
Current Systems

Purpose: Temperature sensitivity is found in all multicelleular organisms, as well as in most primitive life forms. The ubiquity of this temperature sensitivity is an indicator of its effects at the multicellular, cellular and molecular levels [1]. Previous studies have shown that temperature-based regulation is present in the transcriptional process [2]. RNA Thermometers, temperature-sensitive sequences, have been shown to act on heat-shock genes to regulate temperature-dependant systems in many organisms [3,4]. The goal of this study was to characterize the shifts in the functioning of these RNA Thermometers at various temperatures. In addition, using the principle of transcriptional thermoregulation, an automated temperature-responsive system stimulating inverse endothermic and exothermic enzymatic reactions for heat stabilization was proposed. Methods: The endothermic enzymatic reaction was designated as the breakdown of urea, reflecting the function of urease, and the exothermic reaction was designated as the breakdown of hydrogen peroxide, reflecting the function of catalase [5]. Results: The proposed system was built upon the translation of urease and the inhibition of catalase translation at higher temperatures, and the inverse at lower temperatures. As RNA Thermometers can be used only to drive transcription at higher temperatures, the installation of a lac-regulated 2-way system was suggested. This system would also provide a synthetic solution to thermoregulation and the current systems employed today. This system could be applied where the current thermoregulatory systems prove insufficient and could be further developed and optimized to replace them in the future.

scholarly journals The thermal dependence of locomotor performance and muscle contractile function in the salamander Ambystoma tigrinum nebulosum

1987 ◽  
Vol 128 (1) ◽  
pp. 219-233 ◽  
Author(s):  
P. L. Else ◽  
A. F. Bennett
Keyword(s):  
Contractile Function ◽  
Ambystoma Tigrinum ◽  
Maximum Speed ◽  
Locomotor Performance ◽  
Force Output ◽  
Thermal Dependence ◽  
Isometric Twitch ◽  
Q10 Values ◽  
Ambystoma Tigrinum Nebulosum ◽  
Muscle Contractile

The thermal dependence of locomotor performance and in vitro muscle mechanical properties were studied after acclimation at 10 degrees and 20 degrees C in the salamander Ambystoma tigrinum nebulosum Hallowell. Performance measurements included burst and endurance capacities on land and in water. No significant differences in locomotor performance or muscle contractile properties were found between acclimation groups. Locomotor performance had only a slight thermal dependence, with Q10 values of 0.99-1.36 for running and swimming burst capacities (i.e. maximum speed and leg/tail cycling frequency). Running and swimming endurance capacities had thermal ratios of 1.58-1.66. Thermal dependence of muscle contractile rates was higher than that of locomotor performance: rates of force development for both isometric twitch and tetanus and maximal shortening velocity had Q10 values of 1.89-2.01. Maximal power output was also thermally dependent (Q10 = 2.33) and occurred at 38% of maximal (tetanic) force output. Force-generating capacities in isometric twitch and tetanus were relatively temperature-independent.

scholarly journals A Single Point Mutation, Asn16→Lys, Dictates the Temperature-Sensitivity of the Reovirus tsG453 Mutant

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 289
Author(s):  
Kathleen K. M. Glover ◽  
Danica M. Sutherland ◽  
Terence S. Dermody ◽  
Kevin M. Coombs
Keyword(s):  
Amino Acid ◽  
Temperature Sensitivity ◽  
Reverse Genetics ◽  
Core Protein ◽  
Single Point ◽  
Single Amino Acid ◽  
Single Point Mutation ◽  
Temperature Sensitive ◽  
Amino Acid Substitutions ◽  
Gene Encoding

Studies of conditionally lethal mutants can help delineate the structure-function relationships of biomolecules. Temperature-sensitive (ts) mammalian reovirus (MRV) mutants were isolated and characterized many years ago. Two of the most well-defined MRV ts mutants are tsC447, which contains mutations in the S2 gene encoding viral core protein σ2, and tsG453, which contains mutations in the S4 gene encoding major outer-capsid protein σ3. Because many MRV ts mutants, including both tsC447 and tsG453, encode multiple amino acid substitutions, the specific amino acid substitutions responsible for the ts phenotype are unknown. We used reverse genetics to recover recombinant reoviruses containing the single amino acid polymorphisms present in ts mutants tsC447 and tsG453 and assessed the recombinant viruses for temperature-sensitivity by efficiency-of-plating assays. Of the three amino acid substitutions in the tsG453 S4 gene, Asn16-Lys was solely responsible for the tsG453ts phenotype. Additionally, the mutant tsC447 Ala188-Val mutation did not induce a temperature-sensitive phenotype. This study is the first to employ reverse genetics to identify the dominant amino acid substitutions responsible for the tsC447 and tsG453 mutations and relate these substitutions to respective phenotypes. Further studies of other MRV ts mutants are warranted to define the sequence polymorphisms responsible for temperature sensitivity.

The Neurospora crassa cyt-20 gene encodes cytosolic and mitochondrial valyl-tRNA synthetases and may have a second function in addition to protein synthesis

1991 ◽  
Vol 11 (8) ◽  
pp. 4022-4035
Author(s):  
A R Kubelik ◽  
B Turcq ◽  
A M Lambowitz
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Neurospora Crassa ◽  
Temperature Sensitivity ◽  
Temperature Sensitive ◽  
Cellular Transport ◽  
Missense Mutations ◽  
Reading Frame ◽  
Trna Synthetases ◽  
Cytosolic Protein

The cyt-20-1 mutant of Neurospora crassa is a temperature-sensitive, cytochrome b- and aa3-deficient strain that is severely deficient in both mitochondrial and cytosolic protein synthesis (R.A. Collins, H. Bertrand, R.J. LaPolla, and A.M. Lambowitz, Mol. Gen. Genet. 177:73-84, 1979). We cloned the cyt-20+ gene by complementation of the cyt-20-1 mutation and found that it contains a 1,093-amino-acid open reading frame (ORF) that encodes both the cytosolic and mitochondrial valyl-tRNA synthetases (vaIRSs). A second mutation, un-3, which is allelic with cyt-20-1, also results in temperature-sensitive growth, but not in gross deficiencies in cytochromes b and aa3 or protein synthesis. The un-3 mutant had also been reported to have pleiotropic defects in cellular transport process, resulting in resistance to amino acid analogs (M.S. Kappy and R.L. Metzenberg, J. Bacteriol. 94:1629-1637, 1967), but this resistance phenotype is separable from the temperature sensitivity in crosses and may result from a mutation in a different gene. The 1,093-amino-acid ORF encoding vaIRSs is the site of missense mutations resulting in temperature sensitivity in both cyt-20-1 and un-3 and is required for the transformation of both mutants. The opposite strand of the cyt-20 gene encodes an overlapping ORF of 532 amino acids, which may also be functional but is not required for transformation of either mutant. The cyt-20-1 mutation in the vaIRS ORF results in severe deficiencies of both mitochondrial and cytosolic vaIRS activities, whereas the un-3 mutation does not appear to result in a deficiency of these activities or of mitochondrial or cytosolic protein synthesis sufficient to account for its temperature-sensitive growth. The phenotype of the un-3 mutant raises the possibility that the vaIRS ORF has a second function in addition to protein synthesis.

scholarly journals Dysfunction of muscle contraction with impaired intracellular Ca2+ handling in skeletal muscle and the effect of exercise training in male db/db mice

2019 ◽  
Vol 126 (1) ◽  
pp. 170-182 ◽  
Author(s):  
Hiroaki Eshima ◽  
Yoshifumi Tamura ◽  
Saori Kakehi ◽  
Kyoko Nakamura ◽  
Nagomi Kurebayashi ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Exercise Training ◽  
Muscle Contraction ◽  
Contractile Function ◽  
Contractile Force ◽  
Contractile Dysfunction ◽  
Muscle Contractile ◽  
Type 2 Diabetic

Type 2 diabetes is characterized by reduced contractile force production and increased fatigability of skeletal muscle. While the maintenance of Ca2+ homeostasis during muscle contraction is a requisite for optimal contractile function, the mechanisms underlying muscle contractile dysfunction in type 2 diabetes are unclear. Here, we investigated skeletal muscle contractile force and Ca2+ flux during contraction and pharmacological stimulation in type 2 diabetic model mice ( db/db mice). Furthermore, we investigated the effect of treadmill exercise training on muscle contractile function. In male db/db mice, muscle contractile force and peak Ca2+ levels were both lower during tetanic stimulation of the fast-twitch muscles, while Ca2+ accumulation was higher after stimulation compared with control mice. While 6 wk of exercise training did not improve glucose tolerance, exercise did improve muscle contractile dysfunction, peak Ca2+ levels, and Ca2+ accumulation following stimulation in male db/db mice. These data suggest that dysfunctional Ca2+ flux may contribute to skeletal muscle contractile dysfunction in type 2 diabetes and that exercise training may be a promising therapeutic approach for dysfunctional skeletal muscle contraction. NEW & NOTEWORTHY The purpose of this study was to examine muscle contractile function and Ca2+ regulation as well as the effect of exercise training in skeletal muscle in obese diabetic mice ( db/db). We observed impairment of muscle contractile force and Ca2+ regulation in a male type 2 diabetic animal model. These dysfunctions in muscle were improved by 6 wk of exercise training.

scholarly journals Soil organic carbon stabilization mechanisms and temperature sensitivity in old terraced soils

2021 ◽  
Vol 18 (23) ◽  
pp. 6301-6312
Author(s):  
Pengzhi Zhao ◽  
Daniel Joseph Fallu ◽  
Sara Cucchiaro ◽  
Paolo Tarolli ◽  
Clive Waddington ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Temperature Sensitivity ◽  
Land Surface ◽  
C:N Ratio ◽  
Temperature Sensitive ◽  
Organic C ◽  
Fraction Composition ◽  
Soil Burial ◽  
C Cycle

Abstract. Being the most common human-created landforms, terrace construction has resulted in an extensive perturbation of the land surface. However, our mechanistic understanding of soil organic carbon (SOC) (de-)stabilization mechanisms and the persistence of SOC stored in terraced soils is far from complete. Here we explored the factors controlling SOC stability and the temperature sensitivity (Q10) of abandoned prehistoric agricultural terrace soils in NE England using soil fractionation and temperature-sensitive incubation combined with terrace soil burial-age measurements. Results showed that although buried terrace soils contained 1.7 times more unprotected SOC (i.e., coarse particulate organic carbon) than non-terraced soils at comparable soil depths, a significantly lower potential soil respiration was observed relative to a control (non-terraced) profile. This suggests that the burial of former topsoil due to terracing provided a mechanism for stabilizing SOC. Furthermore, we observed a shift in SOC fraction composition from particulate organic C towards mineral-protected C with increasing burial age. This clear shift to more processed recalcitrant SOC with soil burial age also contributes to SOC stability in terraced soils. Temperature sensitivity incubations revealed that the dominant controls on Q10 depend on the terrace soil burial age. At relatively younger ages of soil burial, the reduction in substrate availability due to SOC mineral protection with aging attenuates the intrinsic Q10 of SOC decomposition. However, as terrace soil becomes older, SOC stocks in deep buried horizons are characterized by a higher temperature sensitivity, potentially resulting from the poor SOC quality (i.e., soil C:N ratio). In conclusion, terracing in our study site has stabilized SOC as a result of soil burial during terrace construction. The depth–age patterns of Q10 and SOC fraction composition of terraced soils observed in our study site differ from those seen in non-terraced soils, and this has implications when assessing the effects of climate warming and terrace abandonment on the terrestrial C cycle.

scholarly journals Geographical and Seasonal Thermal Sensitivity of Grazing Pressure by Microzooplankton in Contrasting Marine Ecosystems

2021 ◽  
Vol 12 ◽  
Author(s):  
Marco J. Cabrerizo ◽  
Emilio Marañón
Keyword(s):  
Thermal Sensitivity ◽  
Grazing Pressure ◽  
Open Ocean ◽  
Effect Of Temperature ◽  
Extensive Literature ◽  
Thermal Dependence ◽  
Food Web Structure ◽  
Element Cycling ◽  
Large Variability ◽  
Microzooplankton Grazing

Grazing pressure, estimated as the ratio between microzooplankton grazing and phytoplankton growth rates (g:μ), is a strong determinant of microbial food-web structure and element cycling in the upper ocean. It is generally accepted that g is more sensitive to temperature than μ, but it remains unknown how the thermal dependence (activation energy, Ea) of g:μ varies over spatial and temporal scales. To tackle this uncertainty, we used an extensive literature analysis obtaining 751 paired rate estimates of μ and g from dilution experiments performed throughout the world’s marine environments. On a geographical scale, we found a stimulatory effect of temperature in polar open-ocean (∼0.5 eV) and tropical coastal (∼0.2 eV) regions, and an inhibitory one in the remaining biomes (values between −0.1 and −0.4 eV). On a seasonal scale, the temperature effect on g:μ ratios was stimulatory, particularly in polar environments; however, the large variability existing between estimates resulted in non-significant differences among biomes. We observed that increases in nitrate availability stimulated the temperature dependence of grazing pressure (i.e., led to more positive Ea of g:μ) in open-ocean ecosystems and inhibited it in coastal ones, particularly in polar environments. The percentage of primary production grazed by microzooplankton (∼56%) was similar in all regions. Our results suggest that warming of surface ocean waters could exert a highly variable impact, in terms of both magnitude and direction (stimulation or inhibition), on microzooplankton grazing pressure in different ocean regions.

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