scholarly journals Nifedipine-sensitive calcium channels are involved in polar growth of lily pollen tubes

1985 ◽  
Vol 76 (1) ◽  
pp. 247-254
Author(s):  
H.D. Reiss ◽  
W. Herth
Keyword(s):  
Calcium Channels ◽  
Tip Growth ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Polar Growth ◽  
Treatment Results ◽  
High Tendency ◽  
Lily Pollen ◽  
Internal Calcium

Pollen germination and tube growth of Lilium longiflorum in vitro are affected by 10(−5) M-nifedipine. Germinating ‘tubes’ form broad protuberances along the whole colpus. Short tubes show a high tendency to grow ‘amoeboid-like’ and to branch; or a second tube emerges in another region of the colpus. Longer tubes (greater than or equal to 100 micron) broaden irregularly or swell at their tips. The diameter of the tube can vary drastically within the same tube. With increasing time of treatment many tubes burst. Normal tip growth stops within 10 min, but protoplasmic streaming continues even after 15 h. More or less regularly, wall thickenings are formed along the whole tube or on the flanks of the germinating region after some hours. The internal calcium gradient, visualized by chlorotetracycline (CTC) fluorescence, is also disturbed. Nifedipine treatment results in uniform or irregular CTC fluorescence. Branching tubes temporarily show a new subapical CTC gradient. After 6–8 h of nifedipine treatment many cells are no longer stainable with CTC. The results indicate the presence of nifedipine-sensitive calcium channels in pollen tubes.

scholarly journals Protein Analysis of Pollen Tubes after the Treatments of Membrane Trafficking Inhibitors Gains Insights on Molecular Mechanism Underlying Pollen Tube Polar Growth

2021 ◽  
Vol 40 (2) ◽  
pp. 205-222
Author(s):  
Monica Scali ◽  
Alessandra Moscatelli ◽  
Luca Bini ◽  
Elisabetta Onelli ◽  
Rita Vignani ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Actin Cytoskeleton ◽  
Membrane Trafficking ◽  
Tip Growth ◽  
Male Gametophyte ◽  
Pollen Tubes ◽  
Structural Features ◽  
Two Dimensional Gel Electrophoresis ◽  
Depth Analysis

AbstractPollen tube elongation is characterized by a highly-polarized tip growth process dependent on an efficient vesicular transport system and largely mobilized by actin cytoskeleton. Pollen tubes are an ideal model system to study exocytosis, endocytosis, membrane recycling, and signaling network coordinating cellular processes, structural organization and vesicular trafficking activities required for tip growth. Proteomic analysis was applied to identifyNicotiana tabacumDifferentially Abundant Proteins (DAPs) after in vitro pollen tube treatment with membrane trafficking inhibitors Brefeldin A, Ikarugamycin and Wortmannin. Among roughly 360 proteins separated in two-dimensional gel electrophoresis, a total of 40 spots visibly changing between treated and control samples were identified by MALDI-TOF MS and LC–ESI–MS/MS analysis. The identified proteins were classified according to biological processes, and most proteins were related to pollen tube energy metabolism, including ammino acid synthesis and lipid metabolism, structural features of pollen tube growth as well modification and actin cytoskeleton organization, stress response, and protein degradation. In-depth analysis of proteins corresponding to energy-related pathways revealed the male gametophyte to be a reliable model of energy reservoir and dynamics.

Pronounced cytoplasmic pH gradients are not required for tip growth in plant and fungal cells

1997 ◽  
Vol 110 (10) ◽  
pp. 1187-1198 ◽  
Author(s):  
R.M. Parton ◽  
S. Fischer ◽  
R. Malho ◽  
O. Papasouliotis ◽  
T.C. Jelitto ◽  
...  
Keyword(s):  
Tip Growth ◽  
Cell Types ◽  
Pollen Tubes ◽  
Fine Tuning ◽  
Cytoplasmic Ph ◽  
Dual Emission ◽  
Ph Gradients ◽  
Longitudinal Gradients ◽  
External Ph

The existence of pronounced cytoplasmic pH gradients within the apices of tip-growing cells, and the role of cytoplasmic pH in regulating tip growth, were investigated in three different cell types: vegetative hyphae of Neurospora crassa; pollen tubes of Agapanthus umbellatus; and rhizoids of Dryopteris affinis gametophytes. Examination of cytoplasmic pH in growing cells was performed by simultaneous, dual emission confocal ratio imaging of the pH-sensitive probe carboxy SNARF-1. Considerable attention was paid to the fine tuning of dye loading and imaging parameters to minimise cellular perturbation and assess the extent of dye partitioning into organelles. With optimal conditions, cytoplasmic pH was measured routinely with a precision of between +/−0.03 and +/−0.06 of a pH unit and a spatial resolution of 2.3 microm2. Based on in vitro calibration, estimated values of mean cytoplasmic pH for cells loaded with dye-ester were between 7.15 and 7.25 for the three cell types. After pressure injecting Neurospora hyphae with dextran-conjugated dye, however, the mean cytoplasmic pH was estimated to be 7.57. Dextran dyes are believed to give a better estimate of cytoplasmic pH because of their superior localisation and retention within the cytosol. No significant cytoplasmic pH gradient (delta pH of >0.1 unit) was observed within the apical 50 microm in growing cells of any of the three cell types. Acidification or alkalinisation of the cytoplasm in Neurospora hyphae, using a cell permeant weak acid (propionic acid at pH 7.0) or weak base (trimethylamine at pH 8.0), slowed down but did not abolish growth. However, similar manipulation of the cytoplasmic pH of Agapanthus pollen tubes and Dryopteris rhizoids completely inhibited growth. Modification of external pH affected the growth pattern of all cell types. In hyphae and pollen tubes, changes in external pH were found to have a small transient effect on cytoplasmic pH but the cells rapidly readjusted towards their original pH. Our results suggest that pronounced longitudinal gradients in cytoplasmic pH are not essential for the regulation of tip growth.

Morphology of Cell Injury: An Approach to the EDIT Programme by the Use of Tobacco Pollen Tubes

2002 ◽  
Vol 30 (3) ◽  
pp. 323-329 ◽  
Author(s):  
Udo Kristen ◽  
Natalie Bischoff ◽  
Saskia Lisboa ◽  
Enno Schirmer ◽  
Sören Witt ◽  
...  
Keyword(s):  
Tip Growth ◽  
Cell Injury ◽  
Cytosolic Calcium ◽  
Pollen Tubes ◽  
In Vitro Cytotoxicity ◽  
Toxic Compounds ◽  
In Vitro System ◽  
Tobacco Pollen ◽  
Different Types

Tobacco pollen tubes were used as a standard in vitro system to investigate cell growth aberrations caused by some of the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme chemicals and other toxic compounds. Changes in cytoskeletal pattern were observed in the tube cells by using tubu-lin immunofluorescence and rhodamin–phalloidin fluorescence for the localisation of microtubules and actin filaments, respectively. Four different types of cell malformation were found: screw-like growth, isodiametric tip swelling, hook formation, and pollen grain enlargement. We suggest that these malformations resulted from an interference by the chemicals with the cytosolic calcium gradient which controls tip growth and the orientation of the pollen tube. The results may contribute to a general understanding of toxicity-based cell malformations.

Partial purification of myosin from lily pollen tubes by monitoring with in vitro motility assay

PROTOPLASMA ◽  
1992 ◽  
Vol 170 (1-2) ◽  
pp. 77-85 ◽  
Author(s):  
T. Kohno ◽  
R. Ishikawa ◽  
T. Nagata ◽  
K. Kohama ◽  
T. Shimmen
Keyword(s):  
Pollen Tubes ◽  
Motility Assay ◽  
Partial Purification ◽  
In Vitro Motility Assay ◽  
In Vitro Motility ◽  
Lily Pollen

scholarly journals Uncoupling secretion and tip growth in lily pollen tubes: evidence for the role of calcium in exocytosis

1999 ◽  
Vol 19 (4) ◽  
pp. 379-386 ◽  
Author(s):  
Stephane J. Roy ◽  
Terena L. Holdaway-Clarke ◽  
Grant R. Hackett ◽  
Joseph G. Kunkel ◽  
Elizabeth M. Lord ◽  
...  
Keyword(s):  
Tip Growth ◽  
Pollen Tubes ◽  
Lily Pollen

scholarly journals pH gradients are not associated with tip growth in pollen tubes of Lilium longiflorum

1997 ◽  
Vol 110 (15) ◽  
pp. 1729-1740 ◽  
Author(s):  
M.D. Fricker ◽  
N.S. White ◽  
G. Obermeyer
Keyword(s):  
Pollen Tube ◽  
Tip Growth ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Cytoplasmic Ph ◽  
Clear Zone ◽  
External Application ◽  
Ph Gradients ◽  
External Ph

The cytoplasmic pH of growing pollen tubes of Lilium longiflorum Thunb. was measured using the pH-sensitive fluorescent dye 2′,7′-bis-(carboxyethyl)-5(6′)-carboxyfl uorescein and confocal fluorescence ratio imaging. The average cytoplasmic pH in the clear zone of the pollen tube tip was pH 7.11, and no consistent pH gradients were detected in the clear zone, averaging around -1.00 milli pH unit microm(−1), or along the first 50 microm of the tube (3.62 milli pH units microm[-1]). In addition, no correlation was observed between the absolute tip cytoplasmic pH or the pH gradient and the pollen tube growth rates. Shifts of external pH to more acidic pH values (pH 4.5) caused a relatively small acidification by 0.18 pH units, whereas a more alkaline external pH >7.0 caused a dramatic increase in cytoplasmic pH and growth stopped immediately. Stimulation of the plasma membrane H+-ATPase by fusicoccin, resulted in an increase of tube growth but no change in cytoplasmic pH. On the other hand, vanadate (250–500 microM), a putative inhibitor of the pump, stopped tube growth and a slight cytoplasmic alkalinisation of 0.1 pH units was observed. Vanadate also arrested fusicoccin-stimulated growth and stimulated an increased alkalinisation of around 0.2 pH units. External application of CaCl2 (10 mM) caused a small acidification of less than 0.1 pH units in the clear zone, whilst LaCl3 (250 microM) caused slight and rather variable perturbations in cytoplasmic pH of no more than 0.1 pH units. Both treatments stopped growth. It was inferred from these data that tip-acid cytoplasmic pH gradients do not play a central role in the organisation or maintenance of pollen tube tip growth.

In-vitro germination and growth of lily pollen tubes is affected by protein phosphatase inhibitors

Planta ◽  
1998 ◽  
Vol 207 (2) ◽  
pp. 303-312 ◽  
Author(s):  
Gerhard Obermeyer ◽  
Hildegard Klaushofer ◽  
Marion Nagl ◽  
Margit Höftberger ◽  
Friedrich-Wilhelm Bentrup
Keyword(s):  
Protein Phosphatase ◽  
Pollen Tubes ◽  
In Vitro Germination ◽  
Phosphatase Inhibitors ◽  
Lily Pollen ◽  
Protein Phosphatase Inhibitors ◽  
Germination And Growth

scholarly journals Mechanism of Ca2+ inhibition of cytoplasmic streaming in lily pollen tubes

1988 ◽  
Vol 91 (4) ◽  
pp. 501-509 ◽  
Author(s):  
TADASHI KOHNO ◽  
TERUO SHIMMEN
Keyword(s):  
Actin Filaments ◽  
Cytoplasmic Streaming ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Ionophore A23187 ◽  
Filamentous Actin ◽  
Actin Bundles ◽  
Lily Pollen ◽  
Subsequent Decrease

Using a Ca2+ ionophore, A23187, the free Ca2+ concentration ([Ca2+]) in the cytoplasm of pollen tubes of Lilium longiflorum was controlled from the cell exterior. At [Ca2+] higher than 1.0x10−5M (pCa5.0), cytoplasmic streaming was inhibited, and the inhibition was irreversible. The ATP content did not change, but actin filaments were fragmented and formed aggregates. A subsequent decrease in [Ca2+] almost stopped the progress of the actin filament fragmentation, but filamentous actin did not re-form from the fragmented actin. In a previous paper, we reported that pollen tube organelle movement along characean actin bundles was inhibited by Ca2+ at 10−5M levels and the inhibition was reversible. In the present study, the reversibility was also demonstrated using an in situ Ca2+ treatment. Organelles were isolated from pollen tubes that had been treated with high [Ca2+] and A23187. They moved along characean actin bundles in Ca2+-free medium. It is concluded that Ca2+ inhibition of cytoplasmic streaming can be attributed to both inactivation of myosin and fragmentation of actin. The irreversibility of Ca2+ inhibition in situ is attributed to the irreversible fragmentation of actin filaments.

scholarly journals ROP Gtpase–Dependent Dynamics of Tip-Localized F-Actin Controls Tip Growth in Pollen Tubes

2001 ◽  
Vol 152 (5) ◽  
pp. 1019-1032 ◽  
Author(s):  
Ying Fu ◽  
Guang Wu ◽  
Zhenbiao Yang
Keyword(s):  
Tip Growth ◽  
Fluorescent Protein ◽  
Rho Gtpase ◽  
Pollen Tubes ◽  
Actin Binding ◽  
Apical Region ◽  
Polar Growth ◽  
Actin Organization ◽  
Rop Gtpase ◽  
Rho Family

Tip-growing pollen tubes provide a useful model system to study polar growth. Although roles for tip-focused calcium gradient and tip-localized Rho-family GTPase in pollen tube growth is established, the existence and function of tip-localized F-actin have been controversial. Using the green fluorescent protein–tagged actin-binding domain of mouse talin, we found a dynamic form of tip-localized F-actin in tobacco pollen tubes, termed short actin bundles (SABs). The dynamics of SABs during polar growth in pollen tubes is regulated by Rop1At, a Rop GTPase belonging to the Rho family. When overexpressed, Rop1At transformed SAB into a network of fine filaments and induced a transverse actin band behind the tip, leading to depolarized growth. These changes were due to ectopic Rop1At localization to the apical region of the plasma membrane and were suppressed by guanine dissociation inhibitor overexpression, which removed ectopically localized Rop1At. Rop GTPase–activating protein (RopGAP1) overexpression, or Latrunculin B treatments, also recovered normal actin organization and tip growth in Rop1At-overexpressing tubes. Moreover, overexpression of RopGAP1 alone disrupted SABs and inhibited growth. Finally, SAB oscillates and appears at the tip before growth. Together, these results indicate that the dynamics of tip actin are essential for tip growth and provide the first direct evidence to link Rho GTPase to actin organization in controlling cell polarity and polar growth in plants.

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