- 著者
- Tetsuichi Wazawa Takeharu Nagai
- 出版者
- The Biophysical Society of Japan
- 雑誌
- Biophysics and Physicobiology (ISSN:21894779)
- 巻号頁・発行日
- pp.e200030, (Released:2023-06-28)
Ion currents associated with channel proteins in the presence of membrane potential are ubiquitous in cellular and organelle membranes. When an ion current occurs through a channel protein, Joule heating should occur. However, this Joule heating seems to have been largely overlooked in biology. Here we show theoretical investigation of Joule heating involving channel proteins in biological processes. We used electrochemical potential to derive the Joule’s law for an ion current through an ion transport protein in the presence of membrane potential, and we suggest that heat production and absorption can occur. Simulation of temperature distribution around a single channel protein with the Joule heating revealed that the temperature increase was as small as <10−3 K, although an ensemble of channel proteins was suggested to exhibit a noticeable temperature increase. Thereby, we theoretically investigated the Joule heating of systems containing ensembles of channel proteins. Nerve is known to undergo rapid heat production followed by heat absorption during the action potential, and our simulation of Joule heating for a squid giant axon combined with the Hodgkin-Huxley model successfully reproduced the feature of the heat. Furthermore, we extended the theory of Joule heating to uncoupling protein 1 (UCP1), a solute carrier family transporter, which is important to the non-shivering thermogenesis in brown adipose tissue mitochondria (BATM). Our calculations showed that the Joule heat involving UCP1 was comparable to the literature calorimetry data of BATM. Joule heating of ion transport proteins is likely to be one of important mechanisms of cellular thermogenesis.
- 著者
- Takeharu Nagai Shunsuke Chikuma Kenjiro Hanaoka
- 出版者
- The Biophysical Society of Japan
- 雑誌
- Biophysics and Physicobiology (ISSN:21894779)
- 巻号頁・発行日
- pp.BSJ-2020018, (Released:2020-08-28)
- 著者
- Tetsuichi Wazawa Takeharu Nagai
- 出版者
- The Biophysical Society of Japan
- 雑誌
- Biophysics and Physicobiology (ISSN:21894779)
- 巻号頁・発行日
- vol.20, no.3, pp.e200030, 2023 (Released:2023-07-12)
- 参考文献数
- 43
Ion currents associated with channel proteins in the presence of membrane potential are ubiquitous in cellular and organelle membranes. When an ion current occurs through a channel protein, Joule heating should occur. However, this Joule heating seems to have been largely overlooked in biology. Here we show theoretical investigation of Joule heating involving channel proteins in biological processes. We used electrochemical potential to derive the Joule’s law for an ion current through an ion transport protein in the presence of membrane potential, and we suggest that heat production and absorption can occur. Simulation of temperature distribution around a single channel protein with the Joule heating revealed that the temperature increase was as small as <10–3 K, although an ensemble of channel proteins was suggested to exhibit a noticeable temperature increase. Thereby, we theoretically investigated the Joule heating of systems containing ensembles of channel proteins. Nerve is known to undergo rapid heat production followed by heat absorption during the action potential, and our simulation of Joule heating for a squid giant axon combined with the Hodgkin-Huxley model successfully reproduced the feature of the heat. Furthermore, we extended the theory of Joule heating to uncoupling protein 1 (UCP1), a solute carrier family transporter, which is important to the non-shivering thermogenesis in brown adipose tissue mitochondria (BATM). Our calculations showed that the Joule heat involving UCP1 was comparable to the literature calorimetry data of BATM. Joule heating of ion transport proteins is likely to be one of important mechanisms of cellular thermogenesis.
- 著者
- Quang Tran Kenji Osabe Tetsuyuki Entani Takeharu Nagai
- 出版者
- Japanese Society for Plant Biotechnology
- 雑誌
- Plant Biotechnology (ISSN:13424580)
- 巻号頁・発行日
- vol.38, no.2, pp.197-204, 2021-06-25 (Released:2021-06-25)
- 参考文献数
- 32
- 被引用文献数
- 1
Flower opening is an important phenomenon in plant that indicates the readiness of the flower for pollination leading to petal expansion and pigmentation. This phenomenon has great impact on crop yield, which makes researches of its mechanism attractive for both plant physiology study and agriculture. Gene promoters directing the expression in petal during the petal cell wall modification and expansion when flower opens could be a convenient tool to analyze or monitor gene expression targeting this event. However, there are no reports of isolated gene promoters that can direct gene expression in petal or petal limb during the rapid cell wall dynamics when the flower opens. Xyloglucan endotransglucosylase/hydrolase 7 (XTH7), a cell wall modifying enzyme, was reported having up-regulated gene expression in the petal of Arabidopsis thaliana and Petunia hybrida. In this study, we fused a 1,904 bp length P. hybrida XTH7 promoter with a gene encoding a bright bioluminescent protein (Green enhanced Nano-lantern) to report gene expression and observed petal up-regulated bioluminescence activity by means of a consumer-grade camera. More importantly, this novel promoter demonstrated up-regulated activity in the petal limb of P. hybrida matured flower during flower opening. P. hybrida XTH7 promoter would be a useful tool for flowering study, especially for petal expansion research during flower opening.
- 著者
- Tetsuichi Wazawa Nobuyuki Morimoto Takeharu Nagai Makoto Suzuki
- 出版者
- 一般社団法人 日本生物物理学会
- 雑誌
- Biophysics and Physicobiology (ISSN:21894779)
- 巻号頁・発行日
- vol.12, pp.87-102, 2015 (Released:2015-12-02)
- 参考文献数
- 57
- 被引用文献数
- 1
Investigation of the rotational motion of a fluorescent probe tethered to a protein helps to elucidate the local properties of the solvent and protein near the conjugation site of the probe. In this study, we have developed an instrument for frequency-domain fluorescence (FDF) anisotropy measurements, and studied how the local properties around a protein, actin, can be elucidated from the rotational motion of a dye tethered to actin. Rhodamine 6G (R6G) was attached to Cys-374 using newly-synthesized R6G-maleimide with three different oligo(ethylene glycol) (OEG) linker lengths. The time-resolved anisotropy decay of R6G tethered to G-actin was revealed to be a combination of the two modes of the wobbling motion of R6G and the tumbling motion of G-actin. The rotational diffusion coefficient (RDC) of R6G wobbling was ~0.1 ns–1 at 20°C and increased with OEG linker length. The use of the three R6G-actin conjugates of different linker lengths was useful to not only figure out the linker length dependence of the rotational motion of R6G but also validate the analyses. In the presence of a cosolvent of glycerol, although the tumbling motion of G-actin was retarded in response to the bulk viscosity, the wobbling motion of R6G tethered to actin exhibited an increase of RDC as glycerol concentration increased. This finding suggests an intricate relationship between the fluid properties of the bulk solvent and the local environment around actin.
- 著者
- Kenta Saito Kentaro Kobayashi Tomomi Tani Takeharu Nagai
- 出版者
- Japan Society for Cell Biology
- 雑誌
- Cell Structure and Function (ISSN:03867196)
- 巻号頁・発行日
- vol.33, no.1, pp.133-141, 2008 (Released:2008-09-05)
- 参考文献数
- 21
- 被引用文献数
- 4 4
Multi-point scanning confocal microscopy using a Nipkow disk enables the acquisition of fluorescent images with high spatial and temporal resolutions. Like other single-point scanning confocal systems that use Galvano meter mirrors, a commercially available Nipkow spinning disk confocal unit, Yokogawa CSU10, requires lasers as the excitation light source. The choice of fluorescent dyes is strongly restricted, however, because only a limited number of laser lines can be introduced into a single confocal system. To overcome this problem, we developed an illumination system in which light from a mercury arc lamp is scrambled to make homogeneous light by passing it through a multi-mode optical fiber. This illumination system provides incoherent light with continuous wavelengths, enabling the observation of a wide range of fluorophores. Using this optical system, we demonstrate both the high-speed imaging (up to 100 Hz) of intracellular Ca2+ propagation, and the multi-color imaging of Ca2+ and PKC-γ dynamics in living cells.