Ca2+ and Calmodulin Dynamics during Photopolarization in Fucus serratus Zygotes

Love, John; Brownlee, Colin; Trewavas, Anthony

doi:10.1104/pp.115.1.249

Cited by 52 publications

(36 citation statements)

References 55 publications

(80 reference statements)

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“…The Ca 2ϩ signal at the rhizoid apex is essential for turgor and volume regulation (13) and probably involves the regulation of ion channels that allow osmoregulatory ion efflux (24). Polarized growth requires localized Ca 2ϩ elevation, transduced via Ca 2ϩ ͞calmodulin (25,26), regulation of targeted exocytosis (27), and a functional cytoskeleton (28). Studies with the Mn 2ϩ quench technique revealed a role for Ca 2ϩ influx in the generation of Ca 2ϩ signals in the rhizoid apex (13).…”

Section: Resultsmentioning

confidence: 99%

Elemental propagation of calcium signals in response-specific patterns determined by environmental stimulus strength

Goddard

Manison

Tomos

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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Section: Resultsmentioning

confidence: 99%

Elemental propagation of calcium signals in response-specific patterns determined by environmental stimulus strength

Goddard

Manison

Tomos

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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“…Latrunculin A affects actin polymerization in a manner consistent with the formation of a 1:1 latrunculin-G-actin complex (Coué et al, 1987). The latrunculins have been used to inhibit actin function in a wide variety of systems, including animals (Spector et al, 1989), fungi (Ayscough et al, 1997;Gupta and Heath, 1997), and brown algae (Love et al, 1997;Hable and Kropf, 1998). Currently, few reports have been published on the effects of latrunculins on angiosperms (Bibikova et al, 1999;Zonia et al, 1999) and none on the interaction of latrunculin B (LATB) with actin from any organism in vitro.…”

Section: Introductionmentioning

confidence: 99%

Latrunculin B Has Different Effects on Pollen Germination and Tube Growth

1999

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The actin cytoskeleton is absolutely required for pollen germination and tube growth, but little is known about the regulation of actin polymer concentrations or dynamics in pollen. Here, we report that latrunculin B (LATB), a potent inhibitor of actin polymerization, had effects on pollen that were distinct from those of cytochalasin D. The equilibrium dissociation constant measured for LATB binding to maize pollen actin was determined to be 74 nM. This high affinity for pollen actin suggested that treatment of pollen with LATB would have marked effects on actin function. Indeed, LATB inhibited maize pollen germination half-maximally at 50 nM, yet it blocked pollen tube growth at one-tenth of that concentration. Low concentrations of LATB also caused partial disruption of the actin cytoskeleton in germinated maize pollen, as visualized by light microscopy and fluorescent-phalloidin staining. The amounts of filamentous actin (F-actin) in pollen were quantified by measuring phalloidin binding sites, a sensitive assay that had not been used previously for plant cells. The amount of F-actin in maize pollen increased slightly upon germination, whereas the total actin protein level did not change. LATB treatment caused a dose-dependent depolymerization of F-actin in populations of maize pollen grains and tubes. Moreover, the same concentrations of LATB caused similar depolymerization in pollen grains before germination and in pollen tubes. These data indicate that the increased sensitivity of pollen tube growth to LATB was not due to general destabilization of the actin cytoskeleton or to decreases in F-actin amounts after germination. We postulate that germination is less sensitive to LATB than tube extension because the presence of a small population of LATB-sensitive actin filaments is critical for maintenance of tip growth but not for germination of pollen, or because germination is less sensitive to partial depolymerization of the actin cytoskeleton.

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“…Oospheres are initially spherical with no detectable polarity (Jaffe, 1958). After fertilisation (AF) Fucus zygotes deposit a cell wall within minutes and establish an axis of polarity in response to external cues (such as unidirectional light) that becomes fixed in space (14-18 hours AF) and leads to the germination of a rhizoid at the side facing away from the incident light (16-20 hours AF) (Henry et al, 1996;Love et al, 1997;Novotny and Forman, 1974). Concomitantly zygotes progress through the first cell cycle and divide perpendicularly to the growth axis (Corellou et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Spatial re-organisation of cortical microtubules in vivo during polarisation and asymmetric division ofFucuszygotes

Corellou

Coelho

Bouget

et al. 2005

Journal of Cell Science

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IntroductionMicrotubules perform a variety of essential functions within the cell. The mitotic spindle supports chromosome segregation and determines the position of cleavage in animals (Ahringer, 2003). This array is focused at centrosomes in animals although other non-centrosomal arrays exist that are mostly involved in polarised morphologies of specialised animal cells (Keating and Borisy, 1999). In animals, cortical microtubule (MT) arrays have been described only in very specific cases, such as starfish or Xenopus oocytes and zebrafish zygotes, where they are involved in the establishment of the dorsoventral axis (Jesuthasan and Stahle, 1997;Schroeder and Gard, 1992;Schroeder and Otto, 1984).By contrast, cortical MTs are a common feature of vegetative plant cells, in which they play a key role in shaping the cell by directing deposition of cellulose microfibrils (Mfs) in the cell wall and thereby cell growth (Lloyd and Chan, 2004). In plants the interphase MT array in G1 consists of cortical MTs linked to the plasmalemma and is replaced in G2 by the pre-prophase band cortical array that marks the position of the division plane. This array disappears in late prophase and is followed in succession by the mitotic apparatus and the phragmoplast. The perinuclear MT array is in continuity with the cortical array although it is still not clear whether cortical MTs arise from the translocation of perinuclear MTs or are nucleated de novo at cortical sites or both since there is evidence for both mechanisms (Burk and Ye, 2002;Cyr and Palevitz, 1995;Shaw et al., 2003).Rather less is known about MT distributions in zygotes and embryos of higher plants, owing to their general inaccessibility for direct study. Zygotes of fucoid algae (Fucus, Silvetia) have long served as a cellular model to study fertilisation, polarisation and cell division. Oospheres are initially spherical with no detectable polarity (Jaffe, 1958). After fertilisation (AF) Fucus zygotes deposit a cell wall within minutes and establish an axis of polarity in response to external cues (such as unidirectional light) that becomes fixed in space (14-18 hours AF) and leads to the germination of a rhizoid at the side facing away from the incident light (16-20 hours AF) (Henry et al., 1996;Love et al., 1997;Novotny and Forman, 1974). Concomitantly zygotes progress through the first cell cycle and divide perpendicularly to the growth axis (Corellou et al., 2001). The first asymmetrical division gives rise to the rhizoid and thallus cells with distinct developmental fates . The rhizoid remains the only site of growth of the embryos during several rounds of division. The primary division planes in the rhizoid are oriented transverse to the polar axis whereas the first thallus cell 2723Fucus zygotes polarise and germinate a rhizoid before their first asymmetrical division. The role of microtubules (MTs) in orienting the first division plane has been extensively studied by immunofluorescence approaches. In the present study, the re-organisation of MT arrays during...

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Ca2+ and Calmodulin Dynamics during Photopolarization in Fucus serratus Zygotes

Cited by 52 publications

References 55 publications

Elemental propagation of calcium signals in response-specific patterns determined by environmental stimulus strength

Elemental propagation of calcium signals in response-specific patterns determined by environmental stimulus strength

Latrunculin B Has Different Effects on Pollen Germination and Tube Growth

Spatial re-organisation of cortical microtubules in vivo during polarisation and asymmetric division ofFucuszygotes

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