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The biochemical basis for thermoregulation in heat-producing flowers.

Umekawa Y, Seymour RS, Ito K - Sci Rep (2016)

Bottom Line: Here, we show that respiratory control in homeothermic spadices of skunk cabbage (Symplocarpus renifolius) is achieved by rate-determining biochemical reactions in which the overall thermodynamic activation energy exhibits a negative value.Moreover, NADPH production, catalyzed by mitochondrial isocitrate dehydrogenase in a chemically endothermic reaction, plays a role in the pre-equilibrium reaction.We propose that a law of chemical equilibrium known as Le Châtelier's principle governs the homeothermic control in skunk cabbage.

View Article: PubMed Central - PubMed

Affiliation: United Graduate School of Agricultural Science, Iwate University, 3-18-8 Ueda, Morioka, Iwate, 020-8550, Japan.

ABSTRACT
Thermoregulation (homeothermy) in animals involves a complex mechanism involving thermal receptors throughout the body and integration in the hypothalamus that controls shivering and non-shivering thermogenesis. The flowers of some ancient families of seed plants show a similar degree of physiological thermoregulation, but by a different mechanism. Here, we show that respiratory control in homeothermic spadices of skunk cabbage (Symplocarpus renifolius) is achieved by rate-determining biochemical reactions in which the overall thermodynamic activation energy exhibits a negative value. Moreover, NADPH production, catalyzed by mitochondrial isocitrate dehydrogenase in a chemically endothermic reaction, plays a role in the pre-equilibrium reaction. We propose that a law of chemical equilibrium known as Le Châtelier's principle governs the homeothermic control in skunk cabbage.

No MeSH data available.


Related in: MedlinePlus

Effects of pyruvate on the dynamic temperature response (δ) of Eo in isolated mitochondria.Values for δ of NADPH-NDA/ICDH- and NADH-NDB-mediated oxygen consumptions for AOX capacities were determined in the absence (−) or presence (+) of pyruvate (n = 3). n.s.: not significant.
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f5: Effects of pyruvate on the dynamic temperature response (δ) of Eo in isolated mitochondria.Values for δ of NADPH-NDA/ICDH- and NADH-NDB-mediated oxygen consumptions for AOX capacities were determined in the absence (−) or presence (+) of pyruvate (n = 3). n.s.: not significant.

Mentions: Finally, we determined the effects of pyruvate on δ in AOX-mediated mitochondrial respiration, because pyruvate is known as a positive allosteric modulator of AOX921. In our analysis, AOX capacities in NAPDH-NDA/ICDH- and NADH-NDB-mediated oxygen consumptions showed negative and positive values for δ, respectively (Fig. 5). Such an opposite temperature sensitivity suggests a primarily difference of the mechanistic organizations between NAPDH-NDA/ICDH- and NADH-NDB-mediated oxygen consumption rates, although they share the same AOX-mediated respiration pathway from ubiquinol. Importantly, we found no statistically significant effect of pyruvate on δ values in each treatment (Fig. 5). Therefore, it is unlikely that activation status of AOX regulates the dynamic temperature response (temperature sensitivity) of Eo in isolated mitochondria. Alternatively, temperature-dependent equilibrium shifts of the thermodynamically reversible pre-equilibrium reaction, as shown in the present study, may play a role in thermosensation in homeothermic skunk cabbage.


The biochemical basis for thermoregulation in heat-producing flowers.

Umekawa Y, Seymour RS, Ito K - Sci Rep (2016)

Effects of pyruvate on the dynamic temperature response (δ) of Eo in isolated mitochondria.Values for δ of NADPH-NDA/ICDH- and NADH-NDB-mediated oxygen consumptions for AOX capacities were determined in the absence (−) or presence (+) of pyruvate (n = 3). n.s.: not significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837406&req=5

f5: Effects of pyruvate on the dynamic temperature response (δ) of Eo in isolated mitochondria.Values for δ of NADPH-NDA/ICDH- and NADH-NDB-mediated oxygen consumptions for AOX capacities were determined in the absence (−) or presence (+) of pyruvate (n = 3). n.s.: not significant.
Mentions: Finally, we determined the effects of pyruvate on δ in AOX-mediated mitochondrial respiration, because pyruvate is known as a positive allosteric modulator of AOX921. In our analysis, AOX capacities in NAPDH-NDA/ICDH- and NADH-NDB-mediated oxygen consumptions showed negative and positive values for δ, respectively (Fig. 5). Such an opposite temperature sensitivity suggests a primarily difference of the mechanistic organizations between NAPDH-NDA/ICDH- and NADH-NDB-mediated oxygen consumption rates, although they share the same AOX-mediated respiration pathway from ubiquinol. Importantly, we found no statistically significant effect of pyruvate on δ values in each treatment (Fig. 5). Therefore, it is unlikely that activation status of AOX regulates the dynamic temperature response (temperature sensitivity) of Eo in isolated mitochondria. Alternatively, temperature-dependent equilibrium shifts of the thermodynamically reversible pre-equilibrium reaction, as shown in the present study, may play a role in thermosensation in homeothermic skunk cabbage.

Bottom Line: Here, we show that respiratory control in homeothermic spadices of skunk cabbage (Symplocarpus renifolius) is achieved by rate-determining biochemical reactions in which the overall thermodynamic activation energy exhibits a negative value.Moreover, NADPH production, catalyzed by mitochondrial isocitrate dehydrogenase in a chemically endothermic reaction, plays a role in the pre-equilibrium reaction.We propose that a law of chemical equilibrium known as Le Châtelier's principle governs the homeothermic control in skunk cabbage.

View Article: PubMed Central - PubMed

Affiliation: United Graduate School of Agricultural Science, Iwate University, 3-18-8 Ueda, Morioka, Iwate, 020-8550, Japan.

ABSTRACT
Thermoregulation (homeothermy) in animals involves a complex mechanism involving thermal receptors throughout the body and integration in the hypothalamus that controls shivering and non-shivering thermogenesis. The flowers of some ancient families of seed plants show a similar degree of physiological thermoregulation, but by a different mechanism. Here, we show that respiratory control in homeothermic spadices of skunk cabbage (Symplocarpus renifolius) is achieved by rate-determining biochemical reactions in which the overall thermodynamic activation energy exhibits a negative value. Moreover, NADPH production, catalyzed by mitochondrial isocitrate dehydrogenase in a chemically endothermic reaction, plays a role in the pre-equilibrium reaction. We propose that a law of chemical equilibrium known as Le Châtelier's principle governs the homeothermic control in skunk cabbage.

No MeSH data available.


Related in: MedlinePlus