Haruki Hashimoto

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Chloroplast division comprises a sequence of events that facilitate symmetric binary fission and that involve prokaryotic-like stromal division factors such as tubulin-like GTPase FtsZ and the division site regulator MinD. In Arabidopsis, a nuclear-encoded prokaryotic MinE homolog, AtMinE1, has been characterized in terms of its effects on a dividing or(More)
Nuclear and plastid division in the monoplastidic, unicellular eustigmatophyte alga Nannochloropsis oculata (Heterokonta) was investigated by electron microscopy. The outermost of four membranes of the secondary plastid is continuous with the outer nuclear envelope membrane to form a nucleus-plastid continuum (NPC). Such physical continuity between the(More)
The galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are the predominant lipids in thylakoid membranes and indispensable for photosynthesis. Among the three isoforms that catalyze MGDG synthesis in Arabidopsis thaliana, MGD1 is responsible for most galactolipid synthesis in chloroplasts, whereas MGD2 and MGD3 are(More)
Ultrastructure of the constricting neck of dividing proplastids and young chloroplasts in the first leaves ofAvena sativa was examined by electron microscopy. An electron-dense, “double” ring structure (plastid-dividing ring doublet; PD ring doublet) with a width of 15–40 nm was revealed around the narrow neck of the constricted and dividing plastids by(More)
Division and partitioning of microbodies (peroxisomes) of the green alga Klebsormidium flaccidum, whose cells contain a single microbody, were investigated by electron microscopy. In interphase, the rod-shaped microbody is present between the nucleus and the single chloroplast, oriented perpendicular to the pole-to-pole direction of the future spindle. A(More)
Photosynthetic eukaryotes have evolved plastid division mechanisms since acquisition of plastids through endosymbiosis. The emerging evolutionary origin of the plastid division mechanism is remarkably complex. The constituents of the division apparatus of plastids may have complex origins. The one constituent is the plastid FtsZ ring taken over from the(More)
Nucleoid distribution in chloroplasts and etioplasts at the different developmental stages was examined with the first leaves ofAvena sativa by using a DNA-specific fluorescent probe, 4′6-diamidino-2-phenylindole (DAPI). In light-grown first leaves, three types of plastid nucleoid distribution were recognized. 1. Peripheral distribution in undeveloped(More)
The behaviour and multiplication of pollen plastids have remained elusive despite their crucial involvement in cytoplasmic inheritance. Here, we present live images of plastids in pollen grains and growing tubes from transgenic Arabidopsis thaliana lines expressing stroma-localised FtsZ1–green-fluorescent protein fusion in a vegetative cell-specific manner.(More)
In angiosperms, chlorophyll biosynthesis is light dependent. A key factor in this process is protochlorophyllide oxidoreductase (POR), which requires light to catalyze the reduction of protochlorophyllide to chlorophyllide. It is believed that this protein originated from an ancient cyanobacterial enzyme that was introduced into proto-plant cells during the(More)
The plastokinesis (kinesis of chloroplasts) of a raphidophyte alga,Heterosigma akashiwo, was studied by electron microscopy using rapid freezing and freeze-substitution techniques. The chloroplasts are enveloped by two pairs of tightly appressed double membranes, the inner and the cytoplasmic outer pair. The inner pair constricts to divide in advance of the(More)