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Volume 49 (2024)
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Displaying 1-12 of 12 articles from this issue
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Special Topic : Reviews based on the Special Lectures in the 45th Annual Meeting of the Membrane Society of Japan and Membrane Symposium 2023
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Kazunari Akiyoshi2024 Volume 49 Issue 2 Pages 64-69
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSWe have been conducting research on the development of proteoliposomes incorporating membrane proteins as nanodevices, as well as the creation of polymer vesicle artificial cells with integrated catalytic systems such as enzymes, for uses in drug delivery system (DDS). In recent years, there has been growing attention to extracellular vesicles called exosomes as biomimetic nanocarriers for novel intercellular communication. We are advancing the functional analysis and medical applications of these exosomes. I will introduce some of our recent research related to these biomimetic nano materials inspired by biological membranes.View full abstractDownload PDF (1122K) -
Hiroshi Miyata, Yu Toyoda, Tappei Takada2024 Volume 49 Issue 2 Pages 70-76
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSUrate and vitamin C (VC) are closely related to our health problem. Therefore, it is clinically important to maintain blood urate and VC levels in appropriate ranges. Since both compounds are lipophobic, membrane transporters are necessary to regulate their behavior in our body. As urate transporters, urate transporter 1 and glucose transporter 9 play pivotal roles in the reabsorption of urate from urine. In addition, ATP–binding cassette transporter G2 is a crucial transporter in urate excretion at the small intestine. As VC transporters, sodium–dependent VC transporter 1 and 2 participate in VC uptake into cells in several tissues. However, only by these already–identified transporters, we cannot describe the whole pictures of urate and VC homeostasis. Hence, researchers make great efforts to search for novel transporters that have physiological functions in our body.View full abstractDownload PDF (862K)
Special Topic : Toward an understanding of biological phenomena in cell membranes
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Kohjiro Nagao2024 Volume 49 Issue 2 Pages 77-81
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSCells, the smallest units of life, are separated from the external environment by cell membranes. Cell membranes serve not only as boundaries but also as sites for signal transduction and material transport and production. Phospholipid molecules as well as membrane proteins play crucial roles in these functions of cell membranes. Therefore, to elucidate the underlying molecular mechanisms of cell membrane–dependent cellular processes, understanding cellular phospholipid functions is necessary. Here, I introduce the various functions of cellular phospholipids, focusing on the points that are common to most animal cells. I hope this article provides readers with new insights into phospholipid–dependent biological phenomena in animal cells.View full abstractDownload PDF (709K) -
Yoshihiro Ujihara2024 Volume 49 Issue 2 Pages 82-86
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSThis review delves into the comparative analysis of avian and mammalian cardiomyocytes, focusing on the role of T–tubule membranes in calcium (Ca2+) concentration management and their significance in fostering resilience to mechanical load. Mammalian cardiomyocytes, equipped with complex T–tubule membranes, facilitate uniform and rapid changes in Ca2+ concentration, essential for maintaining resilience under mechanical stress. In contrast, while lacking T–tubule membranes, avian cardiomyocytes have developed unique mechanisms for rapid Ca2+ adjustments. Although avian and mammalian hearts are similar in macroscopic function and structure, differences at the cellular level, particularly in mechanisms of Ca2+ regulation, provide an insightful perspective on evolutionary adaptation.View full abstractDownload PDF (782K) -
Takaaki Sokabe2024 Volume 49 Issue 2 Pages 87-92
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSCell membranes hold an array of receptors and sensors to perceive environmental cues and translate them into intracellular signals. Lipid components play a crucial role, serving not only as a scaffold for receptors but also as essential intracellular signaling molecules. Signaling cascades involving receptors and lipids are fundamental to numerous biological reactions. Nowadays, the concept of ‘multimodal functions’ of receptors has gained attentions, especially following a discovery of thermo–sensitive TRP channels. Recently, I identified new lipid metabolites acting as a regulator of TRP channels downstream of light–activated rhodopsins in Drosophila. Moreover, these cascades from rhodopsins to TRP channels were found to function in both thermosensory neurons and taste neurons, indicating that their diverse roles in various cellular contexts. In this review, I will delve into the physiological functions of rhodopsins, lipid components, and TRP channels, highlighting the potential significance of the multimodality of sensory molecules.View full abstractDownload PDF (783K) -
Rinshi S. Kasai2024 Volume 49 Issue 2 Pages 93-98
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSThe G–protein coupled receptor (GPCR) belongs to one of the most renowned protein super families. Over the past couple of decades, researchers have studied the dynamic dimer–monomer interconversion of GPCRs, potentially mediating their physiological functions. However, the generality and mechanism of this interconversion remain elusive. We developed the new technique for observing membrane proteins at the reconstituted lipid bilayer membrane formed at the narrow space between a glass substrate and Polydimethylsiloxane (PDMS). Using this technique, we discovered that the dynamic dimer formation is primarily regulated by the GPCR itself, rather than by micro– and nano–structures within a live cell.View full abstractDownload PDF (738K)
Special Topic : Frontiers in the analysis of biological membranes and their analogs
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Yuki Maeda, Masashi Kawami, Yasuo Uchida2024 Volume 49 Issue 2 Pages 99-106
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSThe blood–arachnoid barrier (BAB) consists of arachnoid epithelial cells linked by tight junctions, and forms one of the interfaces between blood and cerebrospinal fluid (CSF). The BAB was long believed to be impermeable to water–soluble substances and to play a largely passive role until our in vivo studies demonstrated that it is an active interface. Our quantitative proteomic analyses revealed that multiple transporters (OAT1, OAT3, P–gp, BCRP, MATE1, OCT2, PEPT2, etc) are expressed more abundantly at the BAB than at the blood–cerebrospinal fluid barrier, their membrane localizations are polarized in the BAB, and there are regional differences between the cerebral and spinal cord BAB. These findings would provide the better understanding about the central nervous system kinetics of drugs and endogenous compounds, which cannot be explained by blood–brain and blood–cerebrospinal fluid barriers. Here, we introduce the BAB transport systems and discuss the physiologically and pharmacologically crucial roles of the BAB.View full abstractDownload PDF (1076K) -
Takayuki Kawai2024 Volume 49 Issue 2 Pages 107-110
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSBiological membranes are important interfaces that control the movement of substances and information between cells. In order to develop efficient medical care and drugs, it is necessary to study microscale distribution behavior of drugs such as membrane permeability and intra–tissue diffusion, especially in the field of drug delivery system (DDS). Therefore, ultra–sensitive bioanalysis methods have been developed in which trace sample at the single cell level is collected and measured using nanoelectrospray ionization (nanoESI)–mass spectrometry (MS). While nanoESI–MS can detect drugs contained in trace samples with high sensitivity, it has the disadvantage of being unable to remove contaminant components such as salts, resulting in ionization suppression and poor quantitative performance. To solve this problem, we have developed a calibration method for accurate quantification in contaminated salts and a separation method by removing biological matrix. In this review, two of my research achievements for the trace drug analysis are summarized.View full abstractDownload PDF (809K) -
Kaori Sugihara2024 Volume 49 Issue 2 Pages 111-115
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSPolydiacetylene is a mechanochromic polymer that changes its color and emits fluorescence when it is stimulated by force, heat, pH change etc., used in a variety of sensing applications. However, the fundamental mechanism of its mechanochromism at the nanoscale is still not completely understood because of a lack of technique. Recently, our lab has introduced the dual friction force/fluorescence microscopy setup to characterize polydiacetylene. In this mini–review, we will present our recent results, where polydiacetylene is characterized by this technique.View full abstractDownload PDF (1205K) -
Shin-ya Morita2024 Volume 49 Issue 2 Pages 116-122
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSPhospholipids are amphiphilic molecules and essential to form cell membranes in all organisms including animals, plants, fungi, and bacteria. Phospholipid molecules are composed of a hydrophilic head group and two hydrophobic acyl chains, and divided into classes based on their molecular structures. In mammalian cells, major phospholipid classes are phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidic acid (PA), phosphatidylinositol (PI), phosphatidylglycerol (PG), cardiolipin (CL), and sphingomyelin (SM). In addition to the structural roles in membrane formation, phospholipids play important roles in various cellular functions, including membrane trafficking, intracellular signaling, and cell growth. To further understand the cellular and molecular mechanisms, we have completed the development of enzymatic fluorometric methods for quantifying all major phospholipid classes, namely PC, PE, PS, PA, PI, PG ＋ CL, and SM, which are specific, sensitive and high–throughput. These methods enable us to assess the phospholipid class compositions in cultured cells and their intracellular organelles. In this review, I describe strategies and procedures for the enzymatic fluorometric assays of phospholipid classes.View full abstractDownload PDF (1589K)
Special Topic : Engineering Subjects of Gas Separation Membranes Part 2: Concentration Polarization
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Kenji Haraya2024 Volume 49 Issue 2 Pages 123-134
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSThe concept of concentration polarization is explained, and the degree of polarization induced by factors such as membrane permeability, membrane selectivity, mass transfer coefficient, fluid concentration, and partial pressure difference is investigated by calculation. The results are illustrated so that the reader can estimate the degree of concentration polarization in the membrane under consideration. The experimental determination of the mass transfer coefficients required for the calculation is explained. The reader is also introduced to several previous correlation equations for mass transfer coefficients. Using data from real membranes available in the literature, the possibility of concentration polarization in these membranes is predicted. Problems in the conventional treatment of mass transfer coefficients are also discussed.View full abstractDownload PDF (1348K)
Products Spotlight :
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Yosuke Hanamoto2024 Volume 49 Issue 2 Pages 135-137
Published: 2024
Released on J-STAGE: March 27, 2024
JOURNAL RESTRICTED ACCESSIn order to address temporary treatment needs during the renovation of small–scale sewage treatment plants, a portable temporary wastewater treatment unit was developed and tested. This unit combines the “high performance coagulation sedimentation method” with the “single–tank MBR (membrane bioreactor)” and is suitable for use not only during renovations but also in disaster situations. Through practical experiments, the performance and application methods of the unit were verified, demonstrating its ability to adapt to variations in water temperature and BOD levels, ultimately achieving stable treated water. This technology is intended for deployment as an emergency recovery solution during both renovation periods and unforeseen events.View full abstractDownload PDF (1029K)
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