Limits...
Arrest of cytoplasmic streaming induces algal proliferation in green paramecia.

Takahashi T, Shirai Y, Kosaka T, Hosoya H - PLoS ONE (2007)

Bottom Line: Here, we found that cytoplasmic streaming was arrested in dividing green paramecia and the endosymbiotic algae proliferated only during the arrest of cytoplasmic streaming.Interestingly, arrest of cytoplasmic streaming with pressure or a microtubule drug also induced proliferation of endosymbiotic algae independently of host cell cycle.Furthermore, confocal microscopic observation revealed that a division septum was formed in the constricted area of a dividing paramecium, producing arrest of cytoplasmic streaming.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Biological Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.

ABSTRACT
A green ciliate Paramecium bursaria, bearing several hundreds of endosymbiotic algae, demonstrates rotational microtubule-based cytoplasmic streaming, in which cytoplasmic granules and endosymbiotic algae flow in a constant direction. However, its physiological significance is still unknown. We investigated physiological roles of cytoplasmic streaming in P. bursaria through host cell cycle using video-microscopy. Here, we found that cytoplasmic streaming was arrested in dividing green paramecia and the endosymbiotic algae proliferated only during the arrest of cytoplasmic streaming. Interestingly, arrest of cytoplasmic streaming with pressure or a microtubule drug also induced proliferation of endosymbiotic algae independently of host cell cycle. Thus, cytoplasmic streaming may control the algal proliferation in P. bursaria. Furthermore, confocal microscopic observation revealed that a division septum was formed in the constricted area of a dividing paramecium, producing arrest of cytoplasmic streaming. This is a first report to suggest that cytoplasmic streaming controls proliferation of eukaryotic cells.

Show MeSH
(A) Movement of carmine particles near the division plane in algae-free P. bursaria at dividing phase.An algae-free P. bursaria having carmine particles (arrowheads) was monitored using video-microscopy (Left and Middle panel: 0 min and 5 min after initiating the observation, respectively). The right panel is a schematic diagram of movements of carmine particles. (B) P. bursaria at dividing phase. Microphotographs indicate a differential interference contrast image (a) and the corresponding conventional fluorescence image (b). Scale bar, 50 µm. (C) Serial fluorescence sections of dividing paramecia obtained by confocal microscope. Endosymbionts were eliminated from the division plane in P. bursaria at dividing phase.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2131778&req=5

pone-0001352-g004: (A) Movement of carmine particles near the division plane in algae-free P. bursaria at dividing phase.An algae-free P. bursaria having carmine particles (arrowheads) was monitored using video-microscopy (Left and Middle panel: 0 min and 5 min after initiating the observation, respectively). The right panel is a schematic diagram of movements of carmine particles. (B) P. bursaria at dividing phase. Microphotographs indicate a differential interference contrast image (a) and the corresponding conventional fluorescence image (b). Scale bar, 50 µm. (C) Serial fluorescence sections of dividing paramecia obtained by confocal microscope. Endosymbionts were eliminated from the division plane in P. bursaria at dividing phase.

Mentions: To investigate the mechanism of arrest of cytoplasmic streaming, we monitored the movements of carmine particles near the constricted area of dividing algae-free P. bursaria ingesting carmine powder. As shown in Fig. 4A and Movie S3, the particles did not rotationally move in the whole cell. Further, time lapse images showed that the particles in one daughter cell have not been transferred to another cell (Fig. 4A, right). These data suggest that dividing P. bursaria forms a specific structure, like a plant cell plate, at the constricted area to arrest cytoplasmic streaming. DIC image of a dividing green paramecium clearly showed that there is an area eliminating endosymbionts from a constricted region in dividing paramecia (Figs. 4B, panel a, and Movie S4). Fluorescent observation revealed that endosymbiotic algae were eliminated from this area in dividing paramecia (Figs. 4B, panel b). Interestingly, serial images obtained using confocal microscope revealed that the area forms a kind of division septum (Fig. 4C). From these data, we have deduced that the division septum formed at the constricted area of dividing host cell arrested the rotational cytoplasmic streaming during cytokinesis.


Arrest of cytoplasmic streaming induces algal proliferation in green paramecia.

Takahashi T, Shirai Y, Kosaka T, Hosoya H - PLoS ONE (2007)

(A) Movement of carmine particles near the division plane in algae-free P. bursaria at dividing phase.An algae-free P. bursaria having carmine particles (arrowheads) was monitored using video-microscopy (Left and Middle panel: 0 min and 5 min after initiating the observation, respectively). The right panel is a schematic diagram of movements of carmine particles. (B) P. bursaria at dividing phase. Microphotographs indicate a differential interference contrast image (a) and the corresponding conventional fluorescence image (b). Scale bar, 50 µm. (C) Serial fluorescence sections of dividing paramecia obtained by confocal microscope. Endosymbionts were eliminated from the division plane in P. bursaria at dividing phase.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2131778&req=5

pone-0001352-g004: (A) Movement of carmine particles near the division plane in algae-free P. bursaria at dividing phase.An algae-free P. bursaria having carmine particles (arrowheads) was monitored using video-microscopy (Left and Middle panel: 0 min and 5 min after initiating the observation, respectively). The right panel is a schematic diagram of movements of carmine particles. (B) P. bursaria at dividing phase. Microphotographs indicate a differential interference contrast image (a) and the corresponding conventional fluorescence image (b). Scale bar, 50 µm. (C) Serial fluorescence sections of dividing paramecia obtained by confocal microscope. Endosymbionts were eliminated from the division plane in P. bursaria at dividing phase.
Mentions: To investigate the mechanism of arrest of cytoplasmic streaming, we monitored the movements of carmine particles near the constricted area of dividing algae-free P. bursaria ingesting carmine powder. As shown in Fig. 4A and Movie S3, the particles did not rotationally move in the whole cell. Further, time lapse images showed that the particles in one daughter cell have not been transferred to another cell (Fig. 4A, right). These data suggest that dividing P. bursaria forms a specific structure, like a plant cell plate, at the constricted area to arrest cytoplasmic streaming. DIC image of a dividing green paramecium clearly showed that there is an area eliminating endosymbionts from a constricted region in dividing paramecia (Figs. 4B, panel a, and Movie S4). Fluorescent observation revealed that endosymbiotic algae were eliminated from this area in dividing paramecia (Figs. 4B, panel b). Interestingly, serial images obtained using confocal microscope revealed that the area forms a kind of division septum (Fig. 4C). From these data, we have deduced that the division septum formed at the constricted area of dividing host cell arrested the rotational cytoplasmic streaming during cytokinesis.

Bottom Line: Here, we found that cytoplasmic streaming was arrested in dividing green paramecia and the endosymbiotic algae proliferated only during the arrest of cytoplasmic streaming.Interestingly, arrest of cytoplasmic streaming with pressure or a microtubule drug also induced proliferation of endosymbiotic algae independently of host cell cycle.Furthermore, confocal microscopic observation revealed that a division septum was formed in the constricted area of a dividing paramecium, producing arrest of cytoplasmic streaming.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Biological Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.

ABSTRACT
A green ciliate Paramecium bursaria, bearing several hundreds of endosymbiotic algae, demonstrates rotational microtubule-based cytoplasmic streaming, in which cytoplasmic granules and endosymbiotic algae flow in a constant direction. However, its physiological significance is still unknown. We investigated physiological roles of cytoplasmic streaming in P. bursaria through host cell cycle using video-microscopy. Here, we found that cytoplasmic streaming was arrested in dividing green paramecia and the endosymbiotic algae proliferated only during the arrest of cytoplasmic streaming. Interestingly, arrest of cytoplasmic streaming with pressure or a microtubule drug also induced proliferation of endosymbiotic algae independently of host cell cycle. Thus, cytoplasmic streaming may control the algal proliferation in P. bursaria. Furthermore, confocal microscopic observation revealed that a division septum was formed in the constricted area of a dividing paramecium, producing arrest of cytoplasmic streaming. This is a first report to suggest that cytoplasmic streaming controls proliferation of eukaryotic cells.

Show MeSH