Cold acclimation-induced increase in freezing tolerance is associated with diverse changes in the plasma membrane, which ultimately results in an increase in the cryostability of the plasma membrane during a freeze-thaw excursion and an acceleration of the recovery process after thawing. Many reports clearly show the occurrence of alterations in the plasma membrane during cold acclimation and/or a freeze-thaw cycle. Recently, there is accumulating evidence supporting the presence of plasma membrane microdomains in both animal and plant cells. These microdomains contain lipid and protein composition distinct from other parts of the plasma membrane. Thus, we revisit our past findings of the plasma membrane alterations associated with freezing tolerance by introducing the concept of plasma membrane microdomains. The microdomains in the plasma membrane, which are isolated as detergent-resistant membrane (DRM) fractions, responded to cold acclimation: protein composition in the DRM was altered considerably after cold acclimation. The DRM contained proteins of many important functions including membrane transport, plasma membrane- cell wall interactions (via the cytoskeleton) and membrane trafficking. Based on protein changes in DRMs during cold acclimation, we discuss the function of DRM-localized proteins in cold acclimation and/or freezing tolerance in plants.
Journal Article Angiotensin I Converting Enzyme Inhibitory Activities of Various Fermented Foods Get access Akiko Okamoto, Akiko Okamoto Department of Brewing and Fermentation, Tokyo University of Agriculture, 1–1–1, Sakuragaoka, Setagaya-ku, Tokyo 156, Japan Search for other works by this author on: Oxford Academic Google Scholar Hiroshi Hanagata, Hiroshi Hanagata Department of Brewing and Fermentation, Tokyo University of Agriculture, 1–1–1, Sakuragaoka, Setagaya-ku, Tokyo 156, Japan Search for other works by this author on: Oxford Academic Google Scholar Eiko Matsumoto, Eiko Matsumoto Department of Brewing and Fermentation, Tokyo University of Agriculture, 1–1–1, Sakuragaoka, Setagaya-ku, Tokyo 156, Japan Search for other works by this author on: Oxford Academic Google Scholar Yukio Kawamura, Yukio Kawamura Department of Brewing and Fermentation, Tokyo University of Agriculture, 1–1–1, Sakuragaoka, Setagaya-ku, Tokyo 156, JapanNational Food Research Institute, Ministry of Agriculture, Forestory, and Fisheries, 2–1–2, Kannondai, Tsukuba-shi, Ibaraki 305, Japan Search for other works by this author on: Oxford Academic Google Scholar Yukimichi Koizumi, Yukimichi Koizumi Department of Brewing and Fermentation, Tokyo University of Agriculture, 1–1–1, Sakuragaoka, Setagaya-ku, Tokyo 156, Japan Search for other works by this author on: Oxford Academic Google Scholar Fujiharu Yanagida Fujiharu Yanagida Department of Brewing and Fermentation, Tokyo University of Agriculture, 1–1–1, Sakuragaoka, Setagaya-ku, Tokyo 156, Japan Search for other works by this author on: Oxford Academic Google Scholar Bioscience, Biotechnology, and Biochemistry, Volume 59, Issue 6, 1 January 1995, Pages 1147–1149, https://doi.org/10.1271/bbb.59.1147 Published: 01 January 1995 Article history Received: 31 October 1994 Published: 01 January 1995
Environmental adaptability is essential for plant survival. Though it is well known that a simple cooling or cold shock leads to Ca2+ signals, direct evidence has not been provided that plants use Ca2+ signals as a second messenger in the cold acclimation (CA) process in the field. By developing a technique to analyze Ca2+ signals using confocal cryomicroscopy, we investigated Ca2+ signals under several temperature conditions by combining the start temperature, cooling rate and cooling time duration. In both root and leaf cells, Ca2+ signals rapidly disappeared after cooling stopped, and thereafter under a constant low temperature no Ca2+ signal was observed. Interestingly, under the cooling regime from 2�C to -2�C, non-acclimated plants grown at 23�C hardly showed Ca2+ signals, but cold-acclimated plants at 2�C were able to form Ca2+ signals in root cells. These findings suggest that plants sense temperature decreases with Ca2+ signals while adjusting the temperature sensitivity to their own temperature environment. Furthermore, if the temperature is constant, no Ca2+ signal is induced even during CA. Then, we also focused on the CA under field conditions, rich in temperature fluctuations. In CA under field conditions, the expression patterns of CBF/DREB1 genes were distinctly different from those in artificial CA. Pharmacological studies with Ca2+ channel blockers showed that the Ca2+-induced expression of CBF/DREB1 genes was closely correlated with the amplitude of temperature fluctuation, suggesting that Ca2+ signals regulate CBF/DREB1 gene expression during CA under natural conditions.
Allium fistulosum was investigated as a novel model system to examine the mechanism of freezing resistance in cold hardy plants. The 250 × 50 × 90 µm average cell size and single epidermal cell layer system allowed direct observation of endoplasmic reticulum (ER), functional group localization during acclimation, freezing and thawing on an individual cell basis in live intact tissues. Cells increased freezing resistance from an LT50 of -11°C (non-acclimated) to -25°C under 2 weeks of cold acclimation. Samples were processed using Fourier transform infrared technology (FTIR) on a synchrotron light source and a focal plane array detector. In addition, confocal fluorescent microscopy combined with a cryostage using ER selective dye of ER-Tracker allowed more detailed examination of membrane responses during freezing. Cold acclimation increased the ER volume per cell, and the freeze-induced cell deformation stopped ER streaming and ER vesiculation subsequently occurred through the breakdown in the ER network. Freeze-induced ER vesicles in cold-acclimated cells were larger and more abundant than those in non-acclimated cells. According to FTIR, the carbohydrate/ester fraction and α-helical/β-sheet secondary structure localized in the apoplast/plasma membrane region were most visibly increased during cold acclimation. Results suggest the mechanism of cold acclimation and freezing resistance in very hardy cells may be associated with both alterations in the apoplast/plasma membrane region and the ER cryodynamics. Allium fistulosum appears to be a useful system to obtain direct evidence at both intra and extracellular levels during cold acclimation and the freezing process.
Aging and unhealthy eating habits increase the risk of metabolic disorders such as obesity, diabetes and osteoporosis.One of the applicable ways to prevent these negative health outcomes is daily utilization of food materials and/or food factors which contains physiologically active and safe compounds.Kudzu (Pueraria lobata) is a creeping and tree-climbing plant with long vines belonging to Leguminosae family.It has been used as a food material over thousand years as well as a medicinal plant in oriental countries.This mini review introduces health-beneficial effects of kudzu vine isoflavones and their biokinetics in ovariectomized (OVX) mice.Dietary kudzu vine extracts and a diet consisting of puerarin, the major isoflavone, improved glucose metabolism, weight gain and osteoporosis independent of the estrogen receptormediated pathway in OVX mice.As population ages, health problems associated with age and menopause in women are becoming increasingly notable.The findings in this study suggest that dietary kudzu vine isoflavones and puerarin present a promising approach to prevent life style related diseases like obesity, diabetes and osteoporosis.
Protein disulfide isomerase (PDI), which catalyses the folding of newly synthesized or denatured proteins through correct disulfide formation, was purified from soybean (Glycine max). The enzyme was purified 12,000-fold over crude extracts to apparent homogeneity in six purification steps: 60-70% ammonium sulfate fractionation, and chromatography on DEAE Toyopearl 650M, Q-Sepharose Fast Flow, Hiload Superdex 200 pg, Phenyl Sepharose HP, and TSK G-3000 SW. The native enzyme had a molecular weight of 120 kDa on gel filtration. Subunit molecular weight was estimated as 63 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis, thus indicating the enzyme to be comprised of two identical subunits. The enzyme pH optimum was 8.0 with reactivation of scrambled RNase, and the pI 7.65. The N-terminal amino acid sequence of soybean PDI was homologous to that of mature alfalfa as deduced from the cDNA sequence. Two identical active site sequences, APWCGHCK, were obtained from different proteolytic peptide fragments of soybean PDI. Soybean PDI facilitated reactivation not only of scrambled RNase, but denatured and reduced lysozyme and the Bowman Birk soybean trypsin inhibitor as well. This is the first report to appear on the the purification, characterization and amino acid sequence analysis of the active site of a plant PDI.
Abstract One of the authors, KUMADA (I), has proposed a new classification of humic acids based on their colour and spectral characteristics in the visible and ultra-violet regions. Humic acids can be grouped into four major types by this procedure (A, B, Rp and P types) and evidence for a classification diagram based on the values ΔlogK and RF has recently been presented (2). It is clearly important that the usefulness of this new classification should be investigated by considering other chemical and physical properties of humic acids.
Microdomains in the plasma membrane (PM) have been proposed to be involved in many important cellular events in plant cells. To understand the role of PM microdomains in plant cold acclimation, we isolated the microdomains as detergent-resistant plasma membrane fractions (DRMs) from Arabidopsis seedlings and compared lipid and protein compositions before and after cold acclimation. The DRM was enriched in sterols and glucocerebrosides, and the proportion of free sterols in the DRM increased after cold acclimation. The protein-to-lipid ratio in the DRM was greater than that in the total PM fraction. The protein amount recovered in DRMs decreased gradually during cold acclimation. Cold acclimation further resulted in quantitative changes in DRM protein profiles. Subsequent mass spectrometry and Western blot analyses revealed that P-type H+-ATPases, aquaporins and endocytosis-related proteins increased and, conversely, tubulins, actins and V-type H+-ATPase subunits decreased in DRMs during cold acclimation. Functional categorization of cold-responsive proteins in DRMs suggests that plant PM microdomains function as platforms of membrane transport, membrane trafficking and cytoskeleton interaction. These comprehensive changes in microdomains may be associated with cold acclimation of Arabidopsis.
