Thermal sensitivity and effect of temperature acclimation on ocular serotonin N-acetyltransferase activity in Rana perezi

Oxygen consumption allows measuring the metabolic activity of organisms. Here, we adopted the multi-well plate-based respirometry of the extracellular flux analyzer (Seahorse XF96) to investigate the effect of temperature on the bioenergetics of zebrafish embryos (Danio rerio) in situ. We show that the removal of the embryonic chorion is beneficial for oxygen consumption rates (OCR) and penetration of various mitochondrial inhibitors, and confirm that sedation reduces the variability of OCR. At 48h post-fertilization, embryos (maintained at a routine temperature of 28°C) were exposed to different medium temperatures ranging from 18°C to 37°C for 20h prior OCR measurement. Measurement temperatures from 18°C to 45°C in the XF96 were achieved by lowering the room temperature and active in-built heating. At 18°C assay temperature, basal OCR was low due to decreased ATP-linked respiration, which was not limited by mitochondrial power, as seen in substantial spare respiratory capacity. Basal OCR of the embryos increased with assay temperature and were stable up to 37°C assay temperature, with pre-exposure of 37°C resulting in more thermo-resistant basal OCR measured at 41°C. Adverse effects of the mitochondrial inhibitor oligomycin were seen at 37°C and chemical uncouplers disrupted substrate oxidation gradually with increasing assay temperature. Proton leak respiration increased at assay temperatures above 28°C and compromised the efficiency of ATP production, calculated as coupling efficiency. Thus, temperature impacts mitochondrial respiration by reduced cellular ATP turnover at lower temperatures and by increased proton leak at higher temperatures. This conclusion is coherent with the assessment of heart rate, an independent indicator of systemic metabolic rate, which increased with exposure temperature, peaking at 28°C, and decreased at higher temperatures. Collectively, plate-based respirometry allows assessing distinct parts of mitochondrial energy transduction in zebrafish embryos and investigating the effect of temperature and temperature acclimation on mitochondrial bioenergetics in situ.

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Temperature affects the diffusion of small molecules through cytosol of fish muscle

Journal of Experimental Biology ◽

10.1242/jeb.129.1.191 ◽

1987 ◽

Vol 129 (1) ◽

pp. 191-203 ◽

Cited By ~ 4

Author(s):

B. D. Sidell ◽

J. R. Hazel

Keyword(s):

Small Molecules ◽

Diffusion Coefficients ◽

White Perch ◽

Thermal Sensitivity ◽

Fish Muscle ◽

Temperature Acclimation ◽

Effect Of Temperature ◽

Relative Temperature ◽

D Values

Undiluted cytosolic extracts were prepared from fast glycolytic muscle tissue of white perch (Morone americanus). Diffusion coefficients (D) through the cytosol preparations were estimated in vitro for a series of selected low molecular weight compounds using an experimental diffusion chamber. Determinations were made at 5 degrees and 25 degrees C to assess thermal sensitivity of the process. Non-metabolizable analogues of naturally occurring compounds were employed to avoid chemical alteration of solutes by the catalytically competent preparations during diffusion experiments. Kinematic viscosity of cytosolic extracts, which is a major determinant of diffusive resistance, increases from 2.94 +/− 0.06 to 5.35 +/− 0.02 X 10(−2) cm2 s-1 between temperatures of 25 degrees and 5 degrees C (Q10 = 1.35 +/− 0.01). The diffusion coefficients (D) of D-lactic acid are 2.26 +/− 0.84 and 0.79 +/− 0.15 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C, respectively (Q10 = 1.84 +/− 0.36). The D values of 2-deoxyglucose are 2.87 +/− 1.01 and 1.22 +/− 0.36 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C (Q10 = 1.75 +/− 0.54). The D values of Ca2+ are 2.47 +/− 0.28 and 1.09 +/− 0.36 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C (Q10 = 2.04 +/− 0.36). The D values for the ATP analogue, AMP-PNP, are 0.87 +/− 0.33 and 0.81 +/− 0.15 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C (Q10 = 0.98 +/− 0.12). AMP-PNP is the only compound tested which did not show significant thermal sensitivity of diffusion. Recently reported changes in muscle cell ultrastructure induced by temperature acclimation of fishes may serve to counteract the effect of temperature change on diffusion of key small molecules through the aqueous cytoplasm, thus maintaining flux rates between cellular compartments. These mechanisms may be of considerable import in achieving relative temperature independence of cellular function that is characteristic of many eurythermal aquatic animals.

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

Frontiers in Microbiology ◽

10.3389/fmicb.2021.679863 ◽

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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Effect of Temperature Acclimation on Porcine Physiological Responses to Heat Stress and Associated Properties of Muscle

Journal of Animal Science ◽

10.2527/jas1967.263466x ◽

1967 ◽

Vol 26 (3) ◽

pp. 466-469 ◽

Cited By ~ 6

Author(s):

P. B. Addis ◽

H. R. Johnson ◽

N. W. Thomas ◽

M. D. Judge

Keyword(s):

Heat Stress ◽

Physiological Responses ◽

Temperature Acclimation ◽

Effect Of Temperature

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The effect of temperature acclimation on myocardial β-adrenoceptor density and ligand binding affinity in African catfish (Claris gariepinus)

Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology ◽

10.1016/j.cbpb.2005.04.018 ◽

2005 ◽

Vol 141 (2) ◽

pp. 164-168 ◽

Cited By ~ 5

Author(s):

Linda M. Hanson ◽

Yuen K. Ip ◽

Anthony P. Farrell

Keyword(s):

Ligand Binding ◽

Binding Affinity ◽

Temperature Acclimation ◽

Effect Of Temperature ◽

African Catfish

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Integrating bioenergetics and conservation biology: thermal sensitivity of digestive performance in Eastern Collared Lizards (Crotaphytus collaris) may affect population persistence

Conservation Physiology ◽

10.1093/conphys/coaa018 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Casey L Brewster ◽

Jason Ortega ◽

Steven J Beaupre

Keyword(s):

Thermal Sensitivity ◽

Metabolizable Energy ◽

Effect Of Temperature ◽

Valuable Insight ◽

Feeding Rates ◽

Crotaphytus Collaris ◽

Reduced Body ◽

Heat Loads ◽

Passage Times ◽

Collared Lizards

Abstract Information on bioenergetics can provide valuable insight into the ecology, life history and population dynamics of organisms. For ectothermic animals, thermal sensitivity of digestion is an important determinant of net assimilated energy budgets. A recent study in the Ozark Mountains indicated that eastern collared lizards (Crotaphytus collaris) restricted to encroached glades (characterized by woody vegetation encroachment) experience reduced environmental heat loads and have reduced age-specific growth and reproductive rates compared to populations in intact glades. To assess the potential impact of reduced body temperatures on assimilation rates of C. collaris in encroached glades, we conducted feeding trials across four temperature treatments (28, 31, 34 and 37°C). We tested for temperature effects on voluntary feeding rates, passage times, apparent assimilated energy (AE) and metabolizable energy (ME). Passage times decreased and voluntary feeding rates increased significantly with increasing temperature. Consumption explained the majority of variance in AE and ME, followed by the effect of temperature treatments. Using data on voluntary feeding rates, passage times and ME as a function of temperature, we estimated over a 10-fold increase in predicted daily assimilated energy across temperature treatments (28°C = 0.58 kJ/day, 31°C = 1.20 kJ/day, 34°C = 4.30 kJ/day, 37°C = 7.95 kJ/day). Thus, lower heat loads in encroached glades may cause reduced body temperature and result in restricted energy assimilation rates. Our study provides a novel approach to the integration of bioenergetics and conservation and shows the efficacy of using information on digestive performance to investigate underlying mechanisms in a conservation context.

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