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Kikukatsu Ito - One of the best experts on this subject based on the ideXlab platform.
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Rhythmic temperature control in a homeothermic plant: A field study of thermogenic Japanese Skunk Cabbage, Symplocarpus renifolius
2020Co-Authors: Haruka Tanimoto, Taiga Shibutani, Kota Goto, Kikukatsu ItoAbstract:The spadices of Skunk Cabbage (Symplocarpus renifolius) can generate heat and maintain an internal temperature of about 23°C, even when the ambient air temperature drops below freezing. In this study, we continuously measured the spadix temperatures of Skunk Cabbage together with ambient air temperatures during March 2019 in their natural habitat in northern Honshu on Japan’s main island. Using Fourier transform we showed that the temperature of the thermogenic spadix oscillates over a period of approximately 60 min. Our data suggest that Japanese Skunk Cabbage possesses a novel timekeeping mechanism that may be associated with a homeothermic control of this plant.
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Data analytic study of the homothermal maintenance mechanism of Skunk Cabbage: Capturing pre-equilibrium characteristics using extended poisson model.
Biophysics and physicobiology, 2018Co-Authors: Shuji Kawasaki, Kikukatsu ItoAbstract:A wild plant called Skunk Cabbage is known to heat itself and keep its body warm before spring. We study its homothermal maintenance mechanism from a mesoscopic point of view. We take the increment process of the temperature time series and consider it as 'elastic' force that always tries to backlash its temperature to an intrinsic target temperature. We then propose a kind of extended Poisson distribution for the model of the 'elastic' force. The hypothesis testing result by Kolmogorov-Smirnov test suggests that the proposed distribution is a plausible candidate of the model for the 'elastic' force, on the temperature range in which the system is in equillibrium. In addition, it turns out that the parameters in the model captures well the linear behaviour of the expectations of the 'elastic' force at each of the present temperatures and similarly, the constancy of the variances of the force. Especially, the linearity of the expected increments over displacements of tempertures indicates that the backlash might be considered to be like the elastic force of a spring as described by Fuch's law.
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Thioredoxin o-mediated reduction of mitochondrial alternative oxidase in the thermogenic Skunk Cabbage Symplocarpus renifolius.
Journal of biochemistry, 2018Co-Authors: Yui Umekawa, Kikukatsu ItoAbstract:Thermogenesis in plants involves significant increases in their cyanide-resistant mitochondrial alternative oxidase (AOX) capacity. Because AOX is a non-proton-motive ubiquinol oxidase, the dramatic drop in free energy between ubiquinol and oxygen is dissipated as heat. In the thermogenic Skunk Cabbage (Symplocarpus renifolius), SrAOX is specifically expressed in the florets. Although SrAOX harbours conserved cysteine residues, the details of the mechanisms underlying its redox regulation are poorly understood. In our present study, the two mitochondrial thioredoxin o cDNAs SrTrxo1 and SrTrxo2, were isolated from the thermogenic florets of S. renifolius. The deduced amino acid sequences of the protein products revealed that SrTrxo2 specifically lacks the region corresponding to the α3-helix in SrTrxo1. Expression analysis of thermogenic and non-thermogenic S. renifolius tissues indicated that the SrTrxo1 and SrAOX transcripts are predominantly expressed together in thermogenic florets, whereas SrTrxo2 transcripts are almost undetectable in any tissue. Finally, functional in vitro analysis of recombinant SrTrxo1 and mitochondrial membrane fractions of thermogenic florets indicated its reducing activity on SrAOX proteins. Taken together, these results indicate that SrTrxo1 is likely to play a role in the redox regulation of SrAOX in S. renifolius thermogenic florets.
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Respiration of thermogenic inflorescences of Skunk Cabbage Symplocarpus renifolius in heliox.
Plant cell & environment, 2017Co-Authors: Roger S. Seymour, Kikukatsu Ito, Yui UmekawaAbstract:The respiration rate of the thermogenic inflorescences of Japanese Skunk Cabbage Symplocarpus renifolius can reach 300 nmol s-1 g-1 , which is sufficient to raise spadix temperature (Ts ) up to 15 °C above ambient air temperature (Ta ). Respiration rate is inversely related to Ta , such that the Ts achieves a degree of independence from Ta , an effect known as temperature regulation. Here, we measure oxygen consumption rate (Ṁo2 ) in air (21% O2 in mainly N2 ) and in heliox (21% O2 in He) to investigate the diffusive conductance of the network of gas-filled spaces and the thermoregulatory response. When Ts was clamped at 15 °C, the temperature that produces maximal Ṁo2 in this species, exposure to high diffusivity heliox increased mean Ṁo2 significantly from 137 ± 17 to 202 ± 43 nmol s-1 g-1 FW, indicating that respiration in air is normally limited by diffusion in the gas phase and some mitochondria are unsaturated. When Ta was clamped at 15 °C and Ts was allowed to vary, exposure to heliox reduced Ts 1 °C and increased Ṁo2 significantly from 116 ± 10 to 137 ± 19 nmol s-1 g-1 , indicating that enhanced heat loss by conduction and convection can elicit the thermoregulatory response.
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Metabolic interplay between cytosolic phosphoenolpyruvate carboxylase and mitochondrial alternative oxidase in thermogenic Skunk Cabbage, Symplocarpus renifolius.
Plant signaling & behavior, 2016Co-Authors: Abu Sayed, Yui Umekawa, Kikukatsu ItoAbstract:Skunk Cabbage (Symplocarpus renifolius) blooms in early spring and its inflorescence, referred to as the spadix, can produce enough heat to melt snow. Here, we investigated glycolytic carbon flow at the PEP branch-point in thermogenic spadices. Our analyses revealed that petals and pistils in thermogenic florets exhibited higher expression of SrPEPC and SrAOX transcripts than those of SrPK, SrPEPCK, and SrPEPtase. Moreover, enzymatic analyses showed high activities of PEPC in the extracts from thermogenic florets. Finally, mitochondria from thermogenic florets showed low respiratory activities when pyruvate was used as a substrate, although a significant malate-mediated cyanide-insensitive respiration was observed. Collectively, these results suggest that PEP metabolism, primarily catabolized by PEPC, plays a critical role in thermogenesis in S. renifolius.
Michael Nosonovsky - One of the best experts on this subject based on the ideXlab platform.
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surface micro nanotopography wetting properties and the potential for biomimetic icephobicity of Skunk Cabbage symplocarpus foetidus
Soft Matter, 2014Co-Authors: Rahul Ramachandran, Michael NosonovskyAbstract:Lotus (Nelumbo nucifera) is known for its two remarkable properties: superhydrophobicity and thermogenesis; however, the relationship between these two properties remains obscure. Most botanists agree that thermogenesis helps to attract pollinators, while non-wetting helps to catch pollinators and prevents contamination. Here we investigate the surface micro- and nanotopography and wetting properties of eastern Skunk Cabbage (Symplocarpus foetidus), another thermogenic plant, which is known for its ability to melt snow. The Skunk Cabbage leaves are hydrophobic but not superhydrophobic, and they have high contact angle hysteresis (similar to the rose petal effect). We develop a heat transfer model to relate icephobicity with heat transfer and discuss the biomimetic potential that both thermogenic and superhydrophobic plants may have for icephobicity in soft materials.
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Surface micro/nanotopography, wetting properties and the potential for biomimetic icephobicity of Skunk Cabbage Symplocarpus foetidus.
Soft matter, 2014Co-Authors: Rahul Ramachandran, Michael NosonovskyAbstract:Lotus (Nelumbo nucifera) is known for its two remarkable properties: superhydrophobicity and thermogenesis; however, the relationship between these two properties remains obscure. Most botanists agree that thermogenesis helps to attract pollinators, while non-wetting helps to catch pollinators and prevents contamination. Here we investigate the surface micro- and nanotopography and wetting properties of eastern Skunk Cabbage (Symplocarpus foetidus), another thermogenic plant, which is known for its ability to melt snow. The Skunk Cabbage leaves are hydrophobic but not superhydrophobic, and they have high contact angle hysteresis (similar to the rose petal effect). We develop a heat transfer model to relate icephobicity with heat transfer and discuss the biomimetic potential that both thermogenic and superhydrophobic plants may have for icephobicity in soft materials.
Takehito Inaba - One of the best experts on this subject based on the ideXlab platform.
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Protoplast-Based Transient Expression Combined with Plant Cultivation Systems as a Valuable Tool for Floral Thermogenesis Studies in Aroids
2021Co-Authors: Haruhiko Maekawa, Takehito Inaba, Miyabi Otsubo, Koichiro Mizoguchi, Daiki Koyamatsu, Yasuko Ito-inabaAbstract:Abstract Floral thermogenesis in plants plays a significant role in their reproductive function. Thermogenic aroids constitute a large family in highly thermogenic angiosperms, many of which possess intense heat-producing abilities. Several genes have been proposed to be involved in floral thermogenesis of aroids, but the biological tools to identify the functions of those genes at cellular and molecular levels are lacking. Among the many thermogenic aroids, we focused on Skunk Cabbage (Symplocarpus renifolius) because of its ability to produce intense, durable heat and small aboveground parts compared with other thermogenic aroids. In this study, leaf protoplasts were isolated from potted and shoot tip-cultured Skunk Cabbage plants and used to develop transient assay systems. The isolation protocol included an additional, sucrose gradient centrifugation step, which yielded high-purity protoplasts from both types of plants. The isolation and transfection efficiency of the protoplasts exceeded 1.0 × 105/g fresh weight and 50%, respectively, in both potted and shoot tip-cultured plants. Using this protoplast-based transient expression (PTE) system, we determined the protein localization of three mitochondrial energy-dissipating proteins, SrAOX, SrUCPA, and SrNDA1, fused to green fluorescent protein (GFP). In Skunk Cabbage leaf protoplasts, these three GFP-fused proteins were localized in MitoTracker-stained mitochondria. However, the green fluorescent particles in protoplasts expressing SrUCPA-GFP were enlarged compared with those in protoplasts expressing SrAOX-GFP and SrNDA1-GFP. Our PTE system is a powerful tool for functional gene analysis not only in thermogenic aroids but also in non-thermogenic aroids.
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Characterization of two PEBP genes, SrFT and SrMFT, in thermogenic Skunk Cabbage (Symplocarpus renifolius).
Scientific reports, 2016Co-Authors: Yasuko Ito-inaba, Hiromi Masuko-suzuki, Haruhiko Maekawa, Masao Watanabe, Takehito InabaAbstract:Floral thermogenesis has been found in dozens of primitive seed plants and the reproductive organs in these plants produce heat during anthesis. Thus, characterization of the molecular mechanisms underlying flowering is required to fully understand the role of thermogenesis, but this aspect of thermogenic plant development is largely unknown. In this study, extensive database searches and cloning experiments suggest that thermogenic Skunk Cabbage (Symplocarpus renifolius), which is a member of the family Araceae, possesses two genes encoding phosphatidyl ethanolamine-binding proteins (PEBP), FLOWERING LOCUS T (SrFT) and MOTHER OF FT AND TFL1 (SrMFT). Functional analyses of SrFT and SrMFT in Arabidopsis indicate that SrFT promotes flowering, whereas SrMFT does not. In S. renifolius, the stage- and tissue-specific expression of SrFT was more evident than that of SrMFT. SrFT was highly expressed in flowers and leaves and was mainly localized in fibrovascular tissues. In addition, microarray analysis revealed that, within floral tissues, SrFT was co-regulated with the genes associated with cellular respiration and mitochondrial function, including ALTERNATIVE OXIDASE gene proposed to play a major role in floral thermogenesis. Taken together, these data suggest that, among the PEBP genes, SrFT plays a role in flowering and floral development in the thermogenic Skunk Cabbage.
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Isolation and Gene Expression Analysis of a Papain-Type Cysteine Protease in Thermogenic Skunk Cabbage (Symplocarpus renifolius)
Bioscience biotechnology and biochemistry, 2012Co-Authors: Yasuko Ito-inaba, Masao Watanabe, Hiromi Masuko, Takehito InabaAbstract:Skunk Cabbage (Symplocarpus renifolius) spadices contain abundant transcripts for cysteine protease (CP). From thermogenic spadices, we isolated SrCPA, a highly expressed CP gene that encoded a papain-type CP. SrCPA is structurally similar to other plant CPs, including the senescence-associated CPs found in aroids. The expression of SrCPA increased during floral development, and was observed in all floral tissues except for the stamens.
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The gene expression landscape of thermogenic Skunk Cabbage suggests critical roles for mitochondrial and vacuolar metabolic pathways in the regulation of thermogenesis.
Plant cell & environment, 2011Co-Authors: Yasuko Ito-inaba, Yamato Hida, Masao Watanabe, Hiromi Masuko, Hideo Matsumura, Fumiko Yazu, Ryohei Terauchi, Takehito InabaAbstract:Floral thermogenesis has been described in several plant species. Because of the lack of comprehensive gene expression profiles in thermogenic plants, the molecular mechanisms by which floral thermogenesis is regulated remain to be established. We examined the gene expression landscape of Skunk Cabbage (Symplocarpus renifolius) during thermogenic and post-thermogenic stages and identified expressed sequence tags from different developmental stages of the inflorescences using super serial analysis of gene expression (SuperSAGE). In-depth analysis suggested that cellular respiration and mitochondrial functions are significantly enhanced during the thermogenic stage. In contrast, genes involved in stress responses and protein degradation were significantly up-regulated during post-thermogenic stages. Quantitative comparisons indicated that the expression levels of genes involved in cellular respiration were higher in thermogenic spadices than in Arabidopsis inflorescences. Thermogenesis-associated genes seemed to be expressed abundantly in the peripheral tissues of the spadix. Our results suggest that cellular respiration and mitochondrial metabolism play key roles in heat production during floral thermogenesis. On the other hand, vacuolar cysteine protease and other degradative enzymes seem to accelerate senescence and terminate thermogenesis in the post-thermogenic stage.
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What is critical for plant thermogenesis? Differences in mitochondrial activity and protein expression between thermogenic and non-thermogenic Skunk Cabbages
Planta, 2009Co-Authors: Yasuko Ito-inaba, Yamato Hida, Takehito InabaAbstract:Thermogenesis during the blooming of inflorescence is found in several but not all aroids. To understand what is critical for thermogenesis, we investigated the difference between thermogenic and non-thermogenic Skunk Cabbages ( Symplocarpus renifolius and Lysichiton camtschatcensis ), which are closely related in morphology and phylogeny. Critical parameters of mitochondrial biogenesis, including density, respiratory activity, and protein expression were compared between these two species. Mitochondrial density, respiratory activity, and the amount of alternative oxidase (AOX) in L. camtschatcensis spadix mitochondria were lower than in S. renifolius spadix mitochondria, while the level of uncoupling protein (UCP) was higher. AOX and UCP mRNAs in L. camtschatcensis were constitutively expressed in various tissues, such as the spadix, the spathe, the stalk, and the leaves. cDNA encoding two putative thermogenic proteins, AOX and UCP were isolated from L. camtschatcensis , and their primary structure was analyzed by multiple alignment and phylogenetic tree reconstruction. AOX and UCP protein of two the Skunk Cabbage species are closely related in structure, compared with other isoforms in thermogenic plants. Our results suggest that mitochondrial density, respiratory activity, and protein expression, rather than the primary structure of AOX or UCP proteins, may play critical roles in thermogenesis in plants.
Yasuko Ito-inaba - One of the best experts on this subject based on the ideXlab platform.
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Protoplast-Based Transient Expression Combined with Plant Cultivation Systems as a Valuable Tool for Floral Thermogenesis Studies in Aroids
2021Co-Authors: Haruhiko Maekawa, Takehito Inaba, Miyabi Otsubo, Koichiro Mizoguchi, Daiki Koyamatsu, Yasuko Ito-inabaAbstract:Abstract Floral thermogenesis in plants plays a significant role in their reproductive function. Thermogenic aroids constitute a large family in highly thermogenic angiosperms, many of which possess intense heat-producing abilities. Several genes have been proposed to be involved in floral thermogenesis of aroids, but the biological tools to identify the functions of those genes at cellular and molecular levels are lacking. Among the many thermogenic aroids, we focused on Skunk Cabbage (Symplocarpus renifolius) because of its ability to produce intense, durable heat and small aboveground parts compared with other thermogenic aroids. In this study, leaf protoplasts were isolated from potted and shoot tip-cultured Skunk Cabbage plants and used to develop transient assay systems. The isolation protocol included an additional, sucrose gradient centrifugation step, which yielded high-purity protoplasts from both types of plants. The isolation and transfection efficiency of the protoplasts exceeded 1.0 × 105/g fresh weight and 50%, respectively, in both potted and shoot tip-cultured plants. Using this protoplast-based transient expression (PTE) system, we determined the protein localization of three mitochondrial energy-dissipating proteins, SrAOX, SrUCPA, and SrNDA1, fused to green fluorescent protein (GFP). In Skunk Cabbage leaf protoplasts, these three GFP-fused proteins were localized in MitoTracker-stained mitochondria. However, the green fluorescent particles in protoplasts expressing SrUCPA-GFP were enlarged compared with those in protoplasts expressing SrAOX-GFP and SrNDA1-GFP. Our PTE system is a powerful tool for functional gene analysis not only in thermogenic aroids but also in non-thermogenic aroids.
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Characterization of two PEBP genes, SrFT and SrMFT, in thermogenic Skunk Cabbage (Symplocarpus renifolius).
Scientific reports, 2016Co-Authors: Yasuko Ito-inaba, Hiromi Masuko-suzuki, Haruhiko Maekawa, Masao Watanabe, Takehito InabaAbstract:Floral thermogenesis has been found in dozens of primitive seed plants and the reproductive organs in these plants produce heat during anthesis. Thus, characterization of the molecular mechanisms underlying flowering is required to fully understand the role of thermogenesis, but this aspect of thermogenic plant development is largely unknown. In this study, extensive database searches and cloning experiments suggest that thermogenic Skunk Cabbage (Symplocarpus renifolius), which is a member of the family Araceae, possesses two genes encoding phosphatidyl ethanolamine-binding proteins (PEBP), FLOWERING LOCUS T (SrFT) and MOTHER OF FT AND TFL1 (SrMFT). Functional analyses of SrFT and SrMFT in Arabidopsis indicate that SrFT promotes flowering, whereas SrMFT does not. In S. renifolius, the stage- and tissue-specific expression of SrFT was more evident than that of SrMFT. SrFT was highly expressed in flowers and leaves and was mainly localized in fibrovascular tissues. In addition, microarray analysis revealed that, within floral tissues, SrFT was co-regulated with the genes associated with cellular respiration and mitochondrial function, including ALTERNATIVE OXIDASE gene proposed to play a major role in floral thermogenesis. Taken together, these data suggest that, among the PEBP genes, SrFT plays a role in flowering and floral development in the thermogenic Skunk Cabbage.
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Thermogenesis in Skunk Cabbage (Symplocarpus renifolius): New insights from the ultrastructure and gene expression profiles
Advances in horticultural science, 2014Co-Authors: Yasuko Ito-inabaAbstract:Floral thermogenesis has been found in several plant species. The spadix of one thermoregulatory plant, the Eastern Asian Skunk Cabbage ( Symplocarpus renifolius), can maintain its temperature at approximately 22-26°C for several days, even when the ambient temperature falls below freezing. There are two major stages in Skunk Cabbage inflorescence development: the thermogenic female stage and the non-thermogenic male stage; in the former the spadix can produce massive amounts of heat, whereas in the latter, thermogenesis is undetectable. Based on previous studies, there is a positive correlation between heat production and the abundance of mitochondria in plant tissues and cells, and genes involved in cellular respiration and mitochondrial function are significantly enhanced at the female stage. Taken together, these findings suggest that the increased respiration or mitochondrial abundance observed in thermogenic tissues may be attributable to the high expression of specific genes. This review summarizes new insights into the changes in intracellular structures and gene expression profiles of Skunk Cabbage spadices during the female-male transition and proposes possible processes that are essential for each stage during floral development.
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Isolation and Gene Expression Analysis of a Papain-Type Cysteine Protease in Thermogenic Skunk Cabbage (Symplocarpus renifolius)
Bioscience biotechnology and biochemistry, 2012Co-Authors: Yasuko Ito-inaba, Masao Watanabe, Hiromi Masuko, Takehito InabaAbstract:Skunk Cabbage (Symplocarpus renifolius) spadices contain abundant transcripts for cysteine protease (CP). From thermogenic spadices, we isolated SrCPA, a highly expressed CP gene that encoded a papain-type CP. SrCPA is structurally similar to other plant CPs, including the senescence-associated CPs found in aroids. The expression of SrCPA increased during floral development, and was observed in all floral tissues except for the stamens.
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The gene expression landscape of thermogenic Skunk Cabbage suggests critical roles for mitochondrial and vacuolar metabolic pathways in the regulation of thermogenesis.
Plant cell & environment, 2011Co-Authors: Yasuko Ito-inaba, Yamato Hida, Masao Watanabe, Hiromi Masuko, Hideo Matsumura, Fumiko Yazu, Ryohei Terauchi, Takehito InabaAbstract:Floral thermogenesis has been described in several plant species. Because of the lack of comprehensive gene expression profiles in thermogenic plants, the molecular mechanisms by which floral thermogenesis is regulated remain to be established. We examined the gene expression landscape of Skunk Cabbage (Symplocarpus renifolius) during thermogenic and post-thermogenic stages and identified expressed sequence tags from different developmental stages of the inflorescences using super serial analysis of gene expression (SuperSAGE). In-depth analysis suggested that cellular respiration and mitochondrial functions are significantly enhanced during the thermogenic stage. In contrast, genes involved in stress responses and protein degradation were significantly up-regulated during post-thermogenic stages. Quantitative comparisons indicated that the expression levels of genes involved in cellular respiration were higher in thermogenic spadices than in Arabidopsis inflorescences. Thermogenesis-associated genes seemed to be expressed abundantly in the peripheral tissues of the spadix. Our results suggest that cellular respiration and mitochondrial metabolism play key roles in heat production during floral thermogenesis. On the other hand, vacuolar cysteine protease and other degradative enzymes seem to accelerate senescence and terminate thermogenesis in the post-thermogenic stage.
Takanori Ito - One of the best experts on this subject based on the ideXlab platform.
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Modeling of thermoregulation in the Skunk Cabbage in relation to meteorological factors.
Agricultural and Forest Meteorology, 2009Co-Authors: Ken Takahashi, Kikukatsu Ito, Takanori Ito, Shigeki Chiba, Hiroshi OsadaAbstract:A model is proposed to calculate the spadix temperature of the Skunk Cabbage Symplocarpus foetidus which regulates its internal temperature at around 20 °C during the female stage even when the ambient air temperature drops below freezing. The model is based on energy balance of the spadix under field conditions. The input data are standard meteorological data and spadix parameters. The model output was compared with experimental data collected under different climate conditions. The agreement between observed and calculated spadix temperatures was fairly good.
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Functional Coexpression of the Mitochondrial Alternative Oxidase and Uncoupling Protein Underlies Thermoregulation in the Thermogenic Florets of Skunk Cabbage
Plant physiology, 2007Co-Authors: Yoshihiko Onda, Megumi Ichikawa, Yoshiaki Kato, Kazushige Matsukawa, Yusuke Kakizaki, Yukie Abe, Takanori Ito, Miyuki Morohashi, Yuka Ito, Hiroyuki KoiwaAbstract:Two distinct mitochondrial energy dissipating systems, alternative oxidase (AOX) and uncoupling protein (UCP), have been implicated as crucial components of thermogenesis in plants and animals, respectively. To further clarify the physiological roles of AOX and UCP during homeothermic heat production in the thermogenic Skunk Cabbage (Symplocarpus renifolius), we identified the thermogenic cells and performed expression and functional analyses of these genes in this organism. Thermographic analysis combined with in situ hybridization revealed that the putative thermogenic cells surround the stamens in the florets of Skunk Cabbage and coexpress transcripts for SrAOX, encoding Symplocarpus AOX, and SrUCPb, encoding a novel UCP that lacks a fifth transmembrane segment. Mitochondria isolated from the thermogenic florets exhibited substantial linoleic acid (LA)-inducible uncoupling activities. Moreover, our results demonstrate that LA is capable of inhibiting the mitochondrial AOX pathway, whereas the proportion of pyruvate-stimulated AOX capacity was not significantly affected by LA. Intriguingly, the protein expression levels for SrAOX and SrUCPb were unaffected even when the ambient air temperatures increased from 10.3°C to 23.1°C or from 8.3°C to 24.9°C. Thus, our results suggest that functional coexpression of AOX and UCP underlies the molecular basis of heat production, and that posttranslational modifications of these proteins play a crucial role in regulating homeothermic heat production under conditions of natural ambient temperature fluctuations in Skunk Cabbage.
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Pyruvate-sensitive AOX exists as a non-covalently associated dimer in the homeothermic spadix of the Skunk Cabbage, Symplocarpus renifolius
FEBS letters, 2007Co-Authors: Yoshihiko Onda, Yasuko Ito-inaba, Megumi Ichikawa, Yoshiaki Kato, Kazushige Matsukawa, Yukie Abe, Takanori Ito, Miyuki Morohashi, Yuka Ito, Minoru OtsukaAbstract:The cyanide-resistant alternative oxidase (AOX) is a homodimeric protein whose activity can be regulated by the oxidation/reduction state and by α-keto acids. To further clarify the role of AOX in the Skunk Cabbage, Symplocarpus renifolius, we have performed expression and functional analyses of the encoding gene. Among the various tissues in the Skunk Cabbage, SrAOX transcripts were found to be specifically expressed in the thermogenic spadix. Moreover, our data demonstrate that the SrAOX protein exists as a non-covalently associated dimer in the thermogenic spadix, and is more sensitive to pyruvate than to other carboxylic acids. Our results suggest that the pyruvate-mediated modification of SrAOX activity plays a significant role in thermoregulation in the Skunk Cabbage.
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Modeling of the thermoregulation system in the Skunk Cabbage: Symplocarpus foetidus
Physical Review E, 2007Co-Authors: Ken Takahashi, Yoshihiko Onda, Kikukatsu Ito, Takanori Ito, Shigeki Chiba, T. Endo, Hiroshi OsadaAbstract:This paper presents a model of the thermoregulation system of the spadix of Skunk Cabbage Symplocarpus foetidus which regulates its internal temperature at around $20\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ during flowering even when the ambient air temperature drops below freezing. From the temperature responses of the spadix to changing ambient air temperature, we assumed that the thermoregulation system of the spadix is probably one of negative feedback control. The feedback signals are based on the rate of temperature change of the spadix over time. A signal is factored into the biochemical energy generator, and becomes biochemical energy, some of which becomes heat. Comparing our proposed model temperature responses and those of the living spadix, we found good agreement. In the process of engineering the model, the existence of two regulatory pathways in the thermoregulation system was simulated, and our proposed model appears to provide the necessary elements to explain the fundamental mechanism of the thermoregulation system of S. foetidus.
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Modeling of the thermoregulation system in the Skunk Cabbage: Symplocarpus foetidus.
Physical review. E Statistical nonlinear and soft matter physics, 2007Co-Authors: Ken Takahashi, Yoshihiko Onda, Kikukatsu Ito, Takanori Ito, Shigeki Chiba, T. Endo, Hiroshi OsadaAbstract:This paper presents a model of the thermoregulation system of the spadix of Skunk Cabbage Symplocarpus foetidus which regulates its internal temperature at around 20 degrees C during flowering even when the ambient air temperature drops below freezing. From the temperature responses of the spadix to changing ambient air temperature, we assumed that the thermoregulation system of the spadix is probably one of negative feedback control. The feedback signals are based on the rate of temperature change of the spadix over time. A signal is factored into the biochemical energy generator, and becomes biochemical energy, some of which becomes heat. Comparing our proposed model temperature responses and those of the living spadix, we found good agreement. In the process of engineering the model, the existence of two regulatory pathways in the thermoregulation system was simulated, and our proposed model appears to provide the necessary elements to explain the fundamental mechanism of the thermoregulation system of S. foetidus.