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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.

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(A) Arrest of cytoplasmic streaming in P. bursaria by pressure (10-second intervals).P. bursaria at interphase arresting cytoplasmic streaming under pressure. Ma and Cv indicate macronucleus and contractile vacuole (broken lines), respectively. Scale bar, 20 µm. (B) Cytoplasmic streaming-dependent increase of the number of endosymbionts. A bar graph shows the number of endosymbionts (±S.D.) under pressure or non-pressure (control). The control value is the number of endosymbionts at intephase (stage 1) described in Fig. 1B. * means a statistical difference P<0.02.
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pone-0001352-g002: (A) Arrest of cytoplasmic streaming in P. bursaria by pressure (10-second intervals).P. bursaria at interphase arresting cytoplasmic streaming under pressure. Ma and Cv indicate macronucleus and contractile vacuole (broken lines), respectively. Scale bar, 20 µm. (B) Cytoplasmic streaming-dependent increase of the number of endosymbionts. A bar graph shows the number of endosymbionts (±S.D.) under pressure or non-pressure (control). The control value is the number of endosymbionts at intephase (stage 1) described in Fig. 1B. * means a statistical difference P<0.02.

Mentions: We have shown that cytoplasmic streaming in P. bursaria is arrested both by pressure with glass coverslip spacing and by addition of microtubule drug nocodazole [3]. To further investigate roles of cytoplasmic streaming in P. bursaria, we determined the number of endosymbionts under pressure with a coverslip. As shown in Fig. 2A, the pressure arrested cytoplasmic streaming in P. bursaria at interphase, although the contractile vacuole (Cv) kept moving. Interestingly, endosymbionts started increasing within 2 hrs after initiating arrest of cytoplasmic streaming (Fig. 2B).


Arrest of cytoplasmic streaming induces algal proliferation in green paramecia.

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

(A) Arrest of cytoplasmic streaming in P. bursaria by pressure (10-second intervals).P. bursaria at interphase arresting cytoplasmic streaming under pressure. Ma and Cv indicate macronucleus and contractile vacuole (broken lines), respectively. Scale bar, 20 µm. (B) Cytoplasmic streaming-dependent increase of the number of endosymbionts. A bar graph shows the number of endosymbionts (±S.D.) under pressure or non-pressure (control). The control value is the number of endosymbionts at intephase (stage 1) described in Fig. 1B. * means a statistical difference P<0.02.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0001352-g002: (A) Arrest of cytoplasmic streaming in P. bursaria by pressure (10-second intervals).P. bursaria at interphase arresting cytoplasmic streaming under pressure. Ma and Cv indicate macronucleus and contractile vacuole (broken lines), respectively. Scale bar, 20 µm. (B) Cytoplasmic streaming-dependent increase of the number of endosymbionts. A bar graph shows the number of endosymbionts (±S.D.) under pressure or non-pressure (control). The control value is the number of endosymbionts at intephase (stage 1) described in Fig. 1B. * means a statistical difference P<0.02.
Mentions: We have shown that cytoplasmic streaming in P. bursaria is arrested both by pressure with glass coverslip spacing and by addition of microtubule drug nocodazole [3]. To further investigate roles of cytoplasmic streaming in P. bursaria, we determined the number of endosymbionts under pressure with a coverslip. As shown in Fig. 2A, the pressure arrested cytoplasmic streaming in P. bursaria at interphase, although the contractile vacuole (Cv) kept moving. Interestingly, endosymbionts started increasing within 2 hrs after initiating arrest of cytoplasmic streaming (Fig. 2B).

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