Papers by Shigeyuki Kawano
The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
Proceedings of the National Academy of Sciences, 2013
Peroxisomes (microbodies) are ubiquitous single-membrane–bounded organelles and fulfill essential... more Peroxisomes (microbodies) are ubiquitous single-membrane–bounded organelles and fulfill essential roles in the cellular metabolism. They are found in virtually all eukaryotic cells and basically multiply by division. However, the mechanochemical machinery involved in peroxisome division remains elusive. Here, we first identified the peroxisome-dividing (POD) machinery. We isolated the POD machinery from Cyanidioschyzon merolae , a unicellular red alga containing a single peroxisome. Peroxisomal division in C. merolae can be highly synchronized by light/dark cycles and the microtubule-disrupting agent oryzalin. By proteomic analysis based on the complete genome sequence of C. merolae , we identified a dynamin-related protein 3 (DRP3) ortholog, CmDnm1 (Dnm1), that predominantly accumulated with catalase in the dividing-peroxisome fraction. Immunofluorescence microscopy demonstrated that Dnm1 formed a ring at the division site of the peroxisome. The outlines of the isolated dynamin rin...
Plant and Cell Physiology, Mar 1, 1997
Plant and Cell Physiology, Mar 1, 1995
Protoplasma, Sep 1, 1995
DNA containing structures (cellular, chloroplast and mitochondrial nuclei) were stained with the ... more DNA containing structures (cellular, chloroplast and mitochondrial nuclei) were stained with the fluorochrome DAPI. Fluorescence intensity, as a measure of DNA content, was estimated during the mitotic cycle in synchronized populations of the chlorococcal alga, Scenedesmus quadricauda. In cells yielding eight daughter cells, three consecutive steps in chloroplast DNA increase occurred over one mitotic cycle. The first step was performed shortly after releasing the daughter cells, the second and third steps occurred consecutively during the first half of the mitotic cycle. Commitment to chloroplast DNA replication was chronologically separated from commitment to division of chloroplast nuclei, revealing that these two chloroplast reproductive steps were under different control mechanisms. The replication of chloroptast DNA occurred at a different time to that of cell-nuclear DNA. The coordination of chloroplast reproductive processes and those in the nucleocytoplasmic compartment were governed by the mutual trophic and metabolic dependency of these compartments rather than by any direct or feedback control controlled by either of them.
Protoplasma, Sep 1, 1996
Summary FdUrd (5-fluorodeoxyuridine), a specific inhibitor of thymidylate synthase, was used to s... more Summary FdUrd (5-fluorodeoxyuridine), a specific inhibitor of thymidylate synthase, was used to study the relationship between reproductive processes in chloroplast and nucleocytoplasmic compartments of the chlorococcal algaScenedesmus quadricauda. The courses of DNA replication and nuclear division in both the compartments were followed in populations synchronised by the alternation of light and dark periods. DAPI-staining of DNA-containing structures was used for
Journal of Experimental Botany, 1993
ABSTRACT The behaviour of cell nuclei and organelle nucleoids (organelle nuclei) was studied in t... more ABSTRACT The behaviour of cell nuclei and organelle nucleoids (organelle nuclei) was studied in the root apical meristem of 3-d-old seedlings of Arabidopsis thaliana (Col.). Samples were embedded in Technovit 7100 resin, cut into thin sections and stained with 4′-6-diamidino-2-phenylindole (DAPI) for observation of DNA. DNA synthesis in cell nuclei and organelle nucleoids was investigated using the incorporation of [3H] thymidine or 5-bromo-2′-deoxyuridine (BrdU). Incorporated [3H] thymidine and BrdU were detected by microautoradiography or immunofiuorescence microscopy, respectively. Central cells and cells just above the central cells of the quiescent centre (QC) showed an extremely low activity of DNA synthesis. However, DNA synthesis occurred in at least one organelle nucleoid of all cells in the QC within 24 h. This suggests the cells in the QC are quiescent with regard to nuclear DNA synthesis, but not with regard to the organelle nucleoids.
Planta, Mar 1, 1993
The behavior of cell nuclei, mitochondrial nucleoids (mt-nucleoids) and plastid nucleoids (ptnucl... more The behavior of cell nuclei, mitochondrial nucleoids (mt-nucleoids) and plastid nucleoids (ptnucleoids) was studied in the root apical meristem of Arabidopsis thaliana. Samples were embedded in Technovit 7100 resin, cut into thin sections and stained with 4&#39;-6-diamidino-2-phenylindole for light-microscopic autoradiography and microphotometry. Synthesis of cell nuclear DNA and cell division were both active in the root apical meristem between 0 μm and 300 μm from the central cells. It is estimated that the cells generated in the lower part of the root apical meristem enter the elongation zone after at least four divisions. Throughout the entire meristematic zone, individual cells had mitochondria which contained 1-5 mt-nucleoids. The number of mitochondria increased gradually from 65 to 200 in the meristem of the central cylinder. Therefore, throughout the meristem, individual mitochondria divided either once or twice per mitotic cycle. By contrast, based on the incorporation of [(3)H]thymidine into organelle nucleoids, syntheses of mitochondrial DNA (mtDNA) and plastid DNA (ptDNA) occurred independently of the mitotic cycle and mainly in a restricted region (i.e., the lower part of the root apical meristem). Fluorimetry, using a videointensified microscope photon-counting system, revealed that the amount of mtDNA per mt-nucleoid in the cells in the lower part of the meristem, where mtDNA synthesis was active, corresponded to more than 1 Mbp. By contrast, in the meristematic cells just below the elongation zone of the root tip, the amount of mtDNA per mt-nucleoid fell to approximately 170 kbp. These findings strongly indicate that the amount of mtDNA per mitochondrion, which has been synthesized in the lower part of the meristem, is gradually reduced as a result of continual mitochondrial divisions during low levels of mtDNA synthesis. This phenomenon would explain why differentiated cells in the elongation zone have mitochondria that contain only extremely small amounts of mtDNA.
Bioresource Technology, Apr 1, 2014
The microalgae family Chlorella species are known to accumulate starch and lipids. Although nitro... more The microalgae family Chlorella species are known to accumulate starch and lipids. Although nitrogen or phosphorous deficiencies promote starch and lipids formation in many microalgae, these deficiencies also limit their growth and productivity. Therefore, the Chlorellaceae strains were attempted to increase starch and lipids productivity under highlight intensity conditions (600-μmol photons•m-2 •s-1). The 12-h:12-h light-dark (LD) cycle conditions elicited more stable growth than the continuous light (LL) conditions, whereas the starch and lipids yields increased in LL conditions. The amount of starch and lipids per cell increased in C. viscosa and C. vulgaris in sulfur-deficient medium, and long-chain fatty acids with 20 or more carbon atoms accumulated in cells grown in sulfur-deficient medium. Accumulation of starch and lipids was investigated in eight strains. The accumulation was strain-dependent, and varied according to the medium and light conditions. Five of the eight Chlorella strains exhibited similar accumulation patterns.
日本生物工学会大会講演要旨集, Aug 5, 2014
Planta, Aug 1, 1994
ABSTRACT The behavior of organelle nucleoids and cell nuclei was studied in the shoot apical meri... more ABSTRACT The behavior of organelle nucleoids and cell nuclei was studied in the shoot apical meristem and developing first foliage leaves of Arabidopsis thaliana. Samples were embedded in Technovit 7100 resin, cut into thin sections and stained with 4-6-diamidino-2-phenylindole to observe DNA. Fluorimetry was performed using a video-intensified microscope photon-counting system. The DNA content of individual mitochondria was more than 1 Mbp in the shoot apical meristem and the young leaf primordium, and decreased to approximately 170 kbp in the mature foliage leaf. In contrast, the DNA content of individual plastids was low in the shoot apical meristem and increased until day 7 after sowing. Application of 5-bromo-2-deoxyuridine, an analogue of thymidine, was usesd to investigate DNA synthesis in situ. The activities of DNA synthesis in the mitochondria and plastids changed according to the stage of development. Mitochondrial DNA was actively synthesized in the shoot apical meristem and young leaf primordia. This strongly suggests that the amount of mitochondrial DNA per mitochondrion, which has been synthesized in the shoot apical meristem and young leaf primordium, is gradually reduced due to continual divisions of the mitochondria during low levels of mitochondrial DNA synthesis. Synthesis of DNA in the plastid became active in the leaf primordia following DNA synthesis in the mitochondria, and the small plastids were filled with large plastid nucleotids. This enlargement of the plastid nucleoids occurred before the synthesis of ribulose-1,5-bisphosphate carboxylase/oxygenase and the development of thylakoids.
Communications Biology
The gametes of chlorophytes differ morphologically even in isogamy and are divided into two types... more The gametes of chlorophytes differ morphologically even in isogamy and are divided into two types (α and β) based on the mating type- or sex-specific asymmetric positioning of the mating structure (cell fusion apparatus) with respect to the flagellar beat plane and eyespot, irrespective of the difference in gamete size. However, the relationship between this morphological trait and the mating type or sex determination system is unclear. Using mating type-reversed strains of the isogamous alga Chlamydomonas reinhardtii, produced by deletion or introduction of the mating type-determining gene MID, we revealed that the positioning of the mating structure is associated with conversion of mating types (mt– and mt+), implying that this trait is regulated by MID. Moreover, the dominant mating type is associated with the type β phenotype, as in the chlorophyte species Ulva prolifera. Our findings may provide a genetic basis for mating type- or sex-specific asymmetric positioning of the chlo...
CYTOLOGIA, 2020
The latest issue of Cytologia (Vol. 85, Issue 2) includes a regular paper on the long-awaited kar... more The latest issue of Cytologia (Vol. 85, Issue 2) includes a regular paper on the long-awaited karyotype analysis of the primitive red alga, Cyanidioschyzon merolae 10D, by Kuroiwa et al. (2020) and a technical note by Miyagishima and Fujiwara (2020) introducing a method to induce a controllable gene expression system in C. merolae. In recent years, Cytologia has focused on introducing the latest research on microalgae and has published excellent papers, such as the two mentioned above. An analysis of worldwide trends in microalgae research based on a bibliometric study found that the number of published papers has increased exponentially since 1990 and 2008. The most relevant journals in this field are Bioresource Technology and Algal Research. Similarly, the number of papers in Cytologia is increasing steadily. Much interest is focused on Chlorella and Chlamydomonas. The major keywords appearing in more than 1,000 articles are those related to microalgae culture, such as biomass, biofuels, lipids, and their applications, or methodologies such as bioreactor. Today, microalgae are attracting attention (i) as sources of high-value compounds such as carotenoids, polyunsaturated fatty acids and phycobiliproteins, (ii) as whole biomass used as ingredients for food and feed, (iii) as extracts or processed biomass to produce biofuel and biofertilizers, and (iv) for bioremediation to ameliorate wastewater, soil, and polluted smoke. In this paper, we focus on how algae and microalgae are treated in Cytologia.
Journal of Cell Science, 1992
Organelle DNA synthesis in root meristem and cultured cell line BY-2, both derived from Nicotiana... more Organelle DNA synthesis in root meristem and cultured cell line BY-2, both derived from Nicotiana tabacum cv. Bright Yellow 2, was examined by immunofluorescence microscopy of Technovit sections with antibody against 5-bromodeoxyuridine (BrdU) and co-fluorescent staining with 4′,6-diamidino-2-phenylindole (DAPI) and quantitative Southern hybridization. In the root meristem, the mitochondrial DNAs (mtDNAs) were synthesized in a specific region near to the quiescent center, where a low frequency of DNA synthesis of cell nuclei was observed. The mitochondrial nuclei (nucleoids) changed morphologically from long ellipsoids with a high frequency of DNA synthesis, in the region just above the quiescent center, to granules with a low frequency of DNA synthesis, as cell distance from the quiescent center increased. Similar patterns were observed in the cultured tobacco cell line (BY-2), in which large amounts of preferential synthesis of DNA of both mitochondria and plastids occurred prior ...
CYTOLOGIA, 2019
The genus Chlorella is a well-known member of the green algal class Trebouxiophyceae, which is ch... more The genus Chlorella is a well-known member of the green algal class Trebouxiophyceae, which is characterized by an immotile and asexual life cycle. Here, we performed an analysis of the whole genome and transcriptome of Parachlorella kessleri NIES-2152 with emphasis on the evolution of meiosis and the flagellar proteins. The Parachlorella transcriptomic data showed that the MID-related RWP-RK genes and meiosisspecific and flagellar proteins were expressed; at the transcriptional level, the DNA repair protein RAD50 was upregulated in the stationary phase, with four-fold more reads per kilobase of transcript per million mapped reads (RPKM) compared with the early stage of culture. In contrast, radial spoke protein genes were down-regulated in the stationary phase. These results suggest that genes for meiotic and flagellar proteins are culture stage-dependent and retain their functions. We presume that the algae lost some of the genes for meiosis and the flagella during asexual evolution, but other genes still possess biological functions other than those related to the flagellum and meiosis.
PLANT MORPHOLOGY, 2017
Phosphorus is an essential element for life on the earth and is also crucial for modern agricultu... more Phosphorus is an essential element for life on the earth and is also crucial for modern agriculture, which is currently dependent on inorganic phosphate fertilizers produced from phosphate rock. Polyphosphate-accumulating organisms (PAOs) have been used for an application of biological phosphorus removal from wastewater. Chlorella is well-known trebouxiophycean green microalgae. When we observed Chlorella cells cultured under the sulfur-depleted condition using transmission electron microscopy, electron dense bodies (DBs) are found in the subcellular region. The commonly-used fluorescent dye, 4', 6-diamidino-2-phenylindole (DAPI), can also be used for polyphosphate detection. Fluorescent microscopic observation shows that structure and subcellular distribution of the DBs are resemble with those of polyphosphate granules detected by DAPI. However, the relationship between polyphosphate, DBs and P-accumulation dynamics has been still unclear. Based on the energy dispersive X-ray analysis, the P signal is detected only in DBs. Molybdenum blue assay and 3D-TEM analysis shows that the DB is the site of polyphosphate accumulation during early and middle age of culture, indicating that Chlorella has a potential as a phosphate-accumulating organism.
Silene latifoliais a dioecious flowering plant with sex chromosomes in the family Caryophyllaceae... more Silene latifoliais a dioecious flowering plant with sex chromosomes in the family Caryophyllaceae. Development of a gynoecium and stamens are suppressed in the male and female flowers ofS. latifolia, respectively.Microbtryum lychnidis-dioicaepromotes stamen development when it infects the female flower. If suppression of the stamen and gynoecium development is regulated by the same mechanism, suppression of gynoecium and stamen development is released simultaneously with the infection byM. lychnidis-dioicae. To assess this hypothesis, an asexual mutant, without gynoecium or stamen, was infected withM. lychnidis-dioicae. A filament of the stamen in the infected asexual mutant was elongated at stages 11 and 12 of the flower bud development as well as the male, but the gynoecium did not form. Instead of the gynoecium, a filamentous structure was suppressed as in the male flower. Developmental suppression of the stamen was released byM. lychnidis-dioicae, but that of gynoecium developme...
Plant and Cell Physiology, 2016
Mechanisms of suppression of pistil primordia in male flowers and of stamen primordia in female f... more Mechanisms of suppression of pistil primordia in male flowers and of stamen primordia in female flowers differ in diclinous plants. In this study, we investigated how cell death and cell cycle arrest are related to flower organ formation in Silene latifolia. Using in situ hybridization and a TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, we detected both cell cycle arrest and cell death in suppressed stamens of female flowers and suppressed pistils of male flowers in S. latifolia. In female flowers infected with Microbotryum lychnidis-dioicae, developmental suppression of stamens is released, and cell cycle arrest and cell death do not occur. Smut spores are formed in S. latifolia anthers infected with M. lychnidis-dioicae, followed by cell death in the endothelium, middle layer, tapetal cells and pollen mother cells. Cell death is difficult to detect using a fluorescein isothiocyanate-labeled TUNEL assay due to strong autofluorescence in the anther. We therefore combined a TUNEL assay in an infrared region with transmission electron microscopy to detect cell death in anthers. We show that following infection by M. lychnidis-dioicae, a TUNEL signal was not detected in the endothelium, middle layer or pollen mother cells, and cell death with outflow of cell contents, including the nucleoplast, was observed in tapetal cells.
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Papers by Shigeyuki Kawano