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Ca2+ influx and phosphoinositide signalling are essential for the establishment and maintenance of cell polarity in monospores from the red alga Porphyra yezoensis.

Li L, Saga N, Mikami K - J. Exp. Bot. (2009)

Bottom Line: The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor.Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent.Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan.

ABSTRACT
The asymmetrical distribution of F-actin directed by cell polarity has been observed during the migration of monospores from the red alga Porphyra yezoensis. The significance of Ca2+ influx and phosphoinositide signalling during the formation of cell polarity in migrating monospores was analysed pharmacologically. The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor. Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent. By contrast, inhibition of phospholipase D (PLD) prevented the migration of monospores but not the asymmetrical localization of F-actin. Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

Show MeSH
Effects of light illumination on the early development of monospores. The organization of F-actin (A, C, E) and renascent cell wall synthesis (B, D, F) in monospores incubated in darkness (A, B), with 100 μM DCMU (C, D) and with 1 μM calcium ionophore A23187 in darkness (E, F) for 3 h are indicated. Upper and lower photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.
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fig5: Effects of light illumination on the early development of monospores. The organization of F-actin (A, C, E) and renascent cell wall synthesis (B, D, F) in monospores incubated in darkness (A, B), with 100 μM DCMU (C, D) and with 1 μM calcium ionophore A23187 in darkness (E, F) for 3 h are indicated. Upper and lower photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.

Mentions: As shown in Fig. 5A and B, it was found that migration was prevented in dark-treated monospores in which F-actin was symmetrically distributed and the cell wall was not synthesized. Such effects of darkness were recovered by irradiation with light (data not shown). Moreover, when monospores were irradiated with unilateral light, the directions of migration and light were not correlated (data not shown), indicating that migration and the early development of germlings do not depend on the direction of light. Thus, the regulatory mechanism to establish cell polarity in monospores is different from that of Fucoid zygotes.


Ca2+ influx and phosphoinositide signalling are essential for the establishment and maintenance of cell polarity in monospores from the red alga Porphyra yezoensis.

Li L, Saga N, Mikami K - J. Exp. Bot. (2009)

Effects of light illumination on the early development of monospores. The organization of F-actin (A, C, E) and renascent cell wall synthesis (B, D, F) in monospores incubated in darkness (A, B), with 100 μM DCMU (C, D) and with 1 μM calcium ionophore A23187 in darkness (E, F) for 3 h are indicated. Upper and lower photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2724695&req=5

fig5: Effects of light illumination on the early development of monospores. The organization of F-actin (A, C, E) and renascent cell wall synthesis (B, D, F) in monospores incubated in darkness (A, B), with 100 μM DCMU (C, D) and with 1 μM calcium ionophore A23187 in darkness (E, F) for 3 h are indicated. Upper and lower photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.
Mentions: As shown in Fig. 5A and B, it was found that migration was prevented in dark-treated monospores in which F-actin was symmetrically distributed and the cell wall was not synthesized. Such effects of darkness were recovered by irradiation with light (data not shown). Moreover, when monospores were irradiated with unilateral light, the directions of migration and light were not correlated (data not shown), indicating that migration and the early development of germlings do not depend on the direction of light. Thus, the regulatory mechanism to establish cell polarity in monospores is different from that of Fucoid zygotes.

Bottom Line: The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor.Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent.Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan.

ABSTRACT
The asymmetrical distribution of F-actin directed by cell polarity has been observed during the migration of monospores from the red alga Porphyra yezoensis. The significance of Ca2+ influx and phosphoinositide signalling during the formation of cell polarity in migrating monospores was analysed pharmacologically. The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor. Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent. By contrast, inhibition of phospholipase D (PLD) prevented the migration of monospores but not the asymmetrical localization of F-actin. Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

Show MeSH