scholarly journals Autoradiographs of Pollen Tube Nuclei with Calcium-45

1959 ◽  
Vol 6 (3) ◽  
pp. 339-342 ◽  
Author(s):  
Dale Steffensen ◽  
John A. Bergeron
Keyword(s):  
Pollen Tube ◽  
Growth And Development ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Mitotic Division ◽  
Generative Nucleus ◽  
Tube Nucleus ◽  
Easter Lily ◽  
Nuclear Component ◽  
Sperm Nuclei

Autoradiography with Ca45 has been used to obtain information about the relation between calcium and chromosomes. Labelled pollen from the Easter lily, Lilium longiflorum, was allowed to develop into pollen tubes between 5 and 6 cm. long in the styles of non-radioactive flowers. All of the nuclei, namely the tube nucleus and the two sperm nuclei, retain Ca45 after this period of growth and development. Since the two sperm nuclei have formed during this interval by the mitotic division of the generative nucleus and growth of the tube has occurred under the influence of the tube nucleus, it is inferred that the calcium was bound in a stable nuclear component, the chromosomes.

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.

Identification and localization of three classes of myosins in pollen tubes of Lilium longiflorum and Nicotiana alata

1995 ◽  
Vol 108 (7) ◽  
pp. 2549-2563
Author(s):  
D.D. Miller ◽  
S.P. Scordilis ◽  
P.K. Hepler
Keyword(s):  
Pollen Tube ◽  
Myosin Ii ◽  
Generative Cell ◽  
Freeze Substitution ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Vegetative Nucleus ◽  
Nicotiana Alata ◽  
Myosin V ◽  
Myosin I

The presence and localization of actin and myosin have been examined in pollen tubes of Lilium longiflorum and Nicotiana alata. Immunoblot analysis of pollen tube extracts with antibodies to actin, myosins IA and IB, myosin II, and myosin V reveals the presence of these contractile proteins. Immunofluorescence microscopy using various methods to preserve the pollen tubes; chemical fixation, rapid freeze fixation and freeze substitution (RF-FS) followed by rehydration or by embeddment in a methacrylate mixture, was performed to optimize preservation. Immunocytochemistry reaffirmed that actin is localized longitudinally in the active streaming lanes and near the cortical surface of the pollen tube. Myosin I was localized to the plasma membrane, larger organelles, the surface of the generative cell and the vegetative nucleus, whereas, myosin V was found in the vegetative cytoplasm in a punctate fashion representing smaller organelles. Myosin II subfragment 1 and light meromyosin were localized in a punctate fashion on the larger organelles throughout the vegetative cytoplasm. In addition, isolated generative cells and vegetative nuclei labeled only with the myosin I antibody. Competition studies indicated the specificity of the heterologous antibodies utilized in this study suggesting the presence of three classes of myosins in pollen. These results lead to the following hypothesis: Myosin I may move the generative cell and vegetative nucleus unidirectionally through the pollen tube to the tip, while myosin V moves the smaller organelles and myosins I and II move the larger organelles (bidirectionally) that are involved in growth.

The distribution of calcium in the grass pollen tube

1985 ◽  
Vol 225 (1240) ◽  
pp. 315-327 ◽  
Keyword(s):  
Pollen Tube ◽  
Pollen Dispersal ◽  
Lilium Longiflorum ◽  
Pollen Tubes ◽  
Distal Region ◽  
Tube Growth ◽  
Growth Physiology ◽  
Large Numbers ◽  
The Difference ◽  
Apical Organization

The distribution of calcium in the terminal regions of actively extending pollen tubes of two Gramineae, Zea mays and Pennisetum americanum , has been investigated by chlorotetracycline (CTC) fluorescence and by energy-dispersive X-ray analysis. Neither method reveals a concentration gradient declining from the tip towards the older parts of the tube comparable with that reported from the pollen tubes of Lilium longiflorum . The difference evidently arises from dissimilarities in pollen-tube growth physiology and the apical organization of the tube. Growth is achieved by the insertion of dictyosome-derived vesicles carrying wallprecursor materials at the tube tip. In L . longiflorum these are produced in a subapical zone of the tube, and a characteristic zonation of cytoplasmic organelles in the distal region develops during growth. In the grasses, large numbers of the wall precursor bodies (‘P-particles ’) are produced before pollen dispersal, and are stored in the grain; they are distributed throughout the tube during early growth, and the organelle zonation in the apex is less pronounced. CTC-induced fluorescence is strongly associated with mitochondria, membranes and P-particles, suggesting that the observed distribution of calcium may reflect mainly the distribution of the element held in organelles and membranes rather than mobile Ca 2+ in the cytosol.

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