Ca2+-induced fragmentation of actin filaments in pollen tubes

PROTOPLASMA ◽  
1987 ◽  
Vol 141 (2-3) ◽  
pp. 177-179 ◽  
Author(s):  
T. Kohno ◽  
T. Shimmen
Keyword(s):  
Actin Filaments ◽  
Pollen Tubes

scholarly journals ADF10 shapes the overall organization of apical actin filaments by promoting their turnover and ordering in pollen tubes

2017 ◽  
Vol 130 (23) ◽  
pp. 3988-4001 ◽  
Author(s):  
Yuxiang Jiang ◽  
Juan Wang ◽  
Yurong Xie ◽  
Naizhi Chen ◽  
Shanjin Huang
Keyword(s):  
Actin Filaments ◽  
Pollen Tubes

Microtubules and actin filaments co-localize in pollen tubes ofNicotiana tabacum L. andLilium longiflorum Thunb.

PROTOPLASMA ◽  
1989 ◽  
Vol 150 (1) ◽  
pp. 75-77 ◽  
Author(s):  
Elisabeth S. Pierson ◽  
H. M. P. Kengen ◽  
J. Derksen
Keyword(s):  
Actin Filaments ◽  
Pollen Tubes ◽  
Ofnicotiana Tabacum

scholarly journals Localization of actin in pollen tubes of Ornithogalum virens L.

2014 ◽  
Vol 68 (2) ◽  
pp. 97-102
Author(s):  
Małgorzata Stępka ◽  
Fabricio Ciampolini ◽  
Mauro Cresti ◽  
Maria Charzyńska
Keyword(s):  
Pollen Tube ◽  
Actin Filaments ◽  
Laser Scanning ◽  
Higher Plants ◽  
Generative Cell ◽  
Pollen Tubes ◽  
Confocal Laser ◽  
Vegetative Nucleus ◽  
Ornithogalum Virens

The germinating pollen grain (in vivo on the stigma or in vitro in germination medium) forms a pollen tube which transports the vegetative nucleus and generative cell/two sperm cells participating in the process of double fertilization. The growth of the tube and the transport of organelles and the cells occur due to two major motor systems existing in the pollen tubes of higher plants: the tubuline-dynein/kinesin and the actin-myosin system. In pollen tubes of <em>Ornithogalum virens</em> the actin filaments were labelled with TRITC-phalloidin (2 µg/ml) in the PIPES buffer and the 10% sucrose, without the fixative and DMSO. Omission of the fixative and permeabilizing agent (DMSO) allowed better preservation of the structure, and the "fluorescence" of actin was observed in living pollen tubes. Observations in CLSM (confocal laser scanning microscope) showed that actin is distributed in the vicinity of the cell membrane. This could support the view that actin filaments and the plasmalemma form the pollen tube cortex along which the cytoplasmic movement of organelles, and cell transport occurs.

Cytosolic proteins from tobacco pollen tubes that crosslink microtubules and actin filaments in vitro are metabolic enzymes

Cytoskeleton ◽  
2010 ◽  
Vol 67 (12) ◽  
pp. 745-754 ◽  
Author(s):  
Silvia Romagnoli ◽  
Claudia Faleri ◽  
Luca Bini ◽  
Tobias I. Baskin ◽  
Mauro Cresti
Keyword(s):  
Actin Filaments ◽  
Metabolic Enzymes ◽  
Pollen Tubes ◽  
Cytosolic Proteins ◽  
Tobacco Pollen

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.

Electron Microscopy of Cytoplasmic Contractile Proteins

1978 ◽  
Vol 36 (3) ◽  
pp. 606-614 ◽  
Author(s):  
T.D. Pollard ◽  
P. Maupin
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Three Dimensional ◽  
Uranyl Acetate ◽  
Contractile Proteins ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Cytoplasmic Matrix ◽  
Computer Image Processing ◽  
Nonmuscle Cells

In this paper we review some of the contributions that electron microscopy has made to the analysis of actin and myosin from nonmuscle cells. We place particular emphasis upon the limitations of the ultrastructural techniques used to study these cytoplasmic contractile proteins, because it is not widely recognized how difficult it is to preserve these elements of the cytoplasmic matrix for electron microscopy. The structure of actin filaments is well preserved for electron microscope observation by negative staining with uranyl acetate (Figure 1). In fact, to a resolution of about 3nm the three-dimensional structure of actin filaments determined by computer image processing of electron micrographs of negatively stained specimens (Moore et al., 1970) is indistinguishable from the structure revealed by X-ray diffraction of living muscle.

Destruction of Actin Filaments by Osmium Tetroxide

1977 ◽  
Vol 35 ◽  
pp. 466-467
Author(s):  
P. Maupin-Szamier ◽  
T. D. Pollard
Keyword(s):  
Actin Filaments ◽  
Time Course ◽  
Osmium Tetroxide ◽  
Rabbit Muscle ◽  
Muscle Actin ◽  
Sodium Phosphate Buffer ◽  
Transmission Electron ◽  
The Difference ◽  
Rates Of Decay ◽  
Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

Sign in / Sign up

Export Citation Format

Share Document