Ikujirô Fukuda

Chloroplast division without DNA synthesis during the life cycle of the unicellular alga Cyanidium caldarium M-8 as revealed by quantitative fluorescence microscopy

SummaryThe behavior and DNA content of the cell and chloroplast nuclei (synonymous with nucleoids; ct-nuclei) during the life cycle have been studied in a synchronized population of cells of the unicellular algaCyanidium caldarium M-8. Cells were examined by epifluorescence microscopy after staining with 4′,6-diamidino-2-phenylindole (DAPI), and by fluorimetry using a video-intensified microscope photon-counting system (VIMPICS). The young cell contains a single petal-like chloroplast, a spherical cell nucleus and several mitochondria, and the cell nucleus and the chloroplast divide in that order just prior to cytokinesis. The chloroplast contains a ring-shaped ct-nucleus which is located at the periphery of the chloroplast during the life cycle. During the first 40 h after the initiation of sychronous cultures, the young cell and its chloroplast increase markedly in size, and the DNA contents per cell nucleus and per ct-nucleus increase approximately two times and 16 times the value in 16-endospore cells, respectively. Four endospore divisions then occur, at intervals of approximately 12 h between 40 h and 90 h, after the initiation of synchronous cultures. The volume of each cell, the volume of each chloroplast, the amount of chloroplast DNA (ct-DNA), and the level of pigmented material in the chloroplast are reduced stepwise after each endospore division until finally, at the 16-endospore stage, they reach approximately 1/16 of the original values for the mother cell. The size of the mitotic spindle also is reduced stepwise as the cell divisions proceed. By contrast, the cell nuclei duplicate their DNA during each endospore division cycle. These results and analysis of other components indicate that the chloroplasts divide into two daughter chloroplasts without any DNA synthesis during four successive cycles of endospore division and also that the DNA content of the chloroplast is intimately related to the volume of the chloroplast and the cell and to the level of pigmented material in the cloroplast, but is not related to the DNA content of the cell nuclei.

Low molecular weight carbohydrates in Cyanidium caldarium and some related algae

Abstract Floridoside (2- O -glycerol-α- d -galactopyranoside) and a small amount of iso -floridoside (1- O -glycerol-α- d - galactopyranoside) were found in Cyanidium caldarium . Floridoside was also found in the red algae Porphyridium cruentum and Porphyra yezoensis , although in the latter iso -floridoside was the main component. Sucrose and glucose were found in the green algae Chlorella pyrenoidosa and Scenedesmus obliquus , and also in a blue-green alga, Anacystis nidulans . Another blue-green alga, Phormidium foveolarum , contains mostly trehalose. From these results and from morphological considerations, it is suggested that Cyanidium caldarium belongs to the primitive Rhodophyta.

Floridosides in unicellular hot spring algae

Abstract Cyanidium caldarium strains RK-1, KS-1 and 001 are probably obligate autotrophs, while Chroococcidiopsis sp. strains M-8 and 002 (formerly named Cyanidium caldarium ) are facultative autotrophs. The Cyanidium strains contain floridoside (2- O -glycerol-α- d -galactopyranoside) and a small amount of iso -floridoside (1- O -glycerol-α- d -galactopyranoside), both of which are known to be distributed in Rhodophyta. The Chroococcidiopsis strains also contain floridoside, but no iso -floridoside, under various culture conditions. These results indicate that Cyanidium is clearly distinguishable from Chroococcidiopsis in iso -floridoside content and nutritional properties, and suggest that all strains tested may be closely related to Rhodophyta.

Chloroplast nucleoids in a unicellular hot spring algaCyanidium caldarium and related algae

Algal chloroplast nucleoids were compared by epifluorescent microscopy.Cyanidium caldarium strain RK-1 or 001 has a rod-shaped chloroplast nucleoid whileCyanidium caldarium (Chroococcidiopsis sp.) strain M-8 or 002 has a circular chloroplast nucleoid along the periphery of a multilobed chloroplast.

Hydrocarbons and fatty acids in two strains of the hot spring alga Cyanidium caldarium

Abstract Normal alkanes (n-C14-n-C30) and a diene (C19:2) were found in Cyanidium caldarium RK-1 type with predominance of n-C17, (46.3 %), while Cyanidium M-8 type contained n-alkanes (n-C15-n-C25) and alkenes (C19:1,C21:1) with an abundance of C19:1 (43.4 %). Normal alkanoic acids of odd-carbon numbers, n-C15 (12.7%) and n-C17,(10.5%) aswell as of even-carbon numbers, n-C16 (12.7%) and n-C18 (9.8%) and C18:2 alkenoic acid (53.1%) were found in Cyanidium RK-1, while Cyanidium M-8 mainly contained n-C16 (33.5 %) alkanoic acids, C18:1(33.3 %) and C18:2 (23.7%) alkenoic acids. The acid C18:2 was present only in Cyanidium M-8. These results indicate a considerable difference between the two strains of Cyanidium caldarium, and Cyanidium RK-1 type may be unique among microalgae because it has a significant amount of odd-carbon numbered n-alkanoic acids.

Cyanidium investigations in Japan

The history on study of this enigmatic alga, Cyanidium caldarium in Japan started during the 1940’s. The first full scale publication assigned for this subject can be considered his article ‘Untersuchungen uber die Vegetation der mineralogenazidotrophen Gewasser Japans’ by Negoro (1944). This article was written in German and published in ‘Tokyo Bunridai Kiyo’ (Academic Reports of Tokyo College of Science and Literature). The bulk of this report consists from five parts about 140 pp. and includes: 1. Introduction, 2. Living habitat, 3. Culture, 4. Summarized conclusion, and 5. Literature survey.