Abstract
To gain insight into the characteristics of organelle movement and the underlying actomyosin motility system in tobacco pollen tubes, we collected data points representing sequential organelle positions in control and cytochalasin-treated cells, and in a sample of extruded cytoplasm. These data were utilized to reconstruct approximately 900 tracks, representing individual organelle movements, and to produce a quantitative analysis of the movement properties, supported by statistical tests. Each reconstructed track appeared to be unique and to show irregularities in velocity and direction of movement. The regularity quotient was near 2 at the tip and above 3 elsewhere in the cell, indicating that movement is more vectorial in the tube area. Similarly, the progressiveness ratio showed that there were relatively more straight trajectories in the tube region than at the tip. Consistent with these data, arithmetical dissection revealed a high degree of randomlike movement in the apex, lanes with tip-directed movement along the flanks, and grain-directed movement in the center of the tube. Intercalated lanes with bidirectional movement had lower organelle velocity, suggesting that steric hindrance plays a role. The results from the movement analysis indicate that the axial arrangement of the actin filaments and performance of the actomyosin system increases from tip to base, and that the opposite polarity of the actin filaments in the peripheral (+-ends of acting filaments toward the tip) versus the central cytoplasm (+-ends of actin filaments toward to the grain) is installed within a few minutes in these tip-growing cells.
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- Holdaway-Clarke T. L., Feijo J. A., Hackett G. R., Kunkel J. G., Hepler P. K. Pollen Tube Growth and the Intracellular Cytosolic Calcium Gradient Oscillate in Phase while Extracellular Calcium Influx Is Delayed. Plant Cell. 1997 Nov;9(11):1999–2010. doi: 10.1105/tpc.9.11.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Koles K. J., McLeod K. D., Smith R. S. The determination of the instantaneous velocity of axonally transported organelles from filmed records of their motion. Can J Physiol Pharmacol. 1982 May;60(5):670–679. doi: 10.1139/y82-092. [DOI] [PubMed] [Google Scholar]
- Malho R., Trewavas A. J. Localized Apical Increases of Cytosolic Free Calcium Control Pollen Tube Orientation. Plant Cell. 1996 Nov;8(11):1935–1949. doi: 10.1105/tpc.8.11.1935. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mascarenhas J. P. Molecular Mechanisms of Pollen Tube Growth and Differentiation. Plant Cell. 1993 Oct;5(10):1303–1314. doi: 10.1105/tpc.5.10.1303. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McLean B. G., Huang S. R., McKinney E. C., Meagher R. B. Plants contain highly divergent actin isovariants. Cell Motil Cytoskeleton. 1990;17(4):276–290. doi: 10.1002/cm.970170403. [DOI] [PubMed] [Google Scholar]
- Messerli M., Robinson K. R. Tip localized Ca2+ pulses are coincident with peak pulsatile growth rates in pollen tubes of Lilium longiflorum. J Cell Sci. 1997 Jun;110(Pt 11):1269–1278. doi: 10.1242/jcs.110.11.1269. [DOI] [PubMed] [Google Scholar]
- Miller D. D., Scordilis S. P., Hepler P. K. Identification and localization of three classes of myosins in pollen tubes of Lilium longiflorum and Nicotiana alata. J Cell Sci. 1995 Jul;108(Pt 7):2549–2563. doi: 10.1242/jcs.108.7.2549. [DOI] [PubMed] [Google Scholar]
- Mustard C. A., Derksen S., Tataryn D. Intensive use of mental health care. Can J Psychiatry. 1996 Mar;41(2):93–101. doi: 10.1177/070674379604100206. [DOI] [PubMed] [Google Scholar]
- Overstreet J. W., Katz D. F., Hanson F. W., Fonseca J. R. A simple inexpensive method for objective assessment of human sperm movement characteristics. Fertil Steril. 1979 Feb;31(2):162–172. [PubMed] [Google Scholar]
- Pierson E. S., Miller D. D., Callaham D. A., Shipley A. M., Rivers B. A., Cresti M., Hepler P. K. Pollen tube growth is coupled to the extracellular calcium ion flux and the intracellular calcium gradient: effect of BAPTA-type buffers and hypertonic media. Plant Cell. 1994 Dec;6(12):1815–1828. doi: 10.1105/tpc.6.12.1815. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pierson E. S., Miller D. D., Callaham D. A., van Aken J., Hackett G., Hepler P. K. Tip-localized calcium entry fluctuates during pollen tube growth. Dev Biol. 1996 Feb 25;174(1):160–173. doi: 10.1006/dbio.1996.0060. [DOI] [PubMed] [Google Scholar]
- Qian H., Sheetz M. P., Elson E. L. Single particle tracking. Analysis of diffusion and flow in two-dimensional systems. Biophys J. 1991 Oct;60(4):910–921. doi: 10.1016/S0006-3495(91)82125-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Taylor Loverine P., Hepler Peter K. POLLEN GERMINATION AND TUBE GROWTH. Annu Rev Plant Physiol Plant Mol Biol. 1997 Jun;48(NaN):461–491. doi: 10.1146/annurev.arplant.48.1.461. [DOI] [PubMed] [Google Scholar]
- de Win A. H., Pierson E. S., Timmer C., Lichtscheidl I. K., Derksen J. Interactive computer-assisted position acquisition procedure designed for the analysis of organelle movement in pollen tubes. Cytometry. 1998 Aug 1;32(4):263–267. doi: 10.1002/(sici)1097-0320(19980801)32:4<263::aid-cyto1>3.0.co;2-j. [DOI] [PubMed] [Google Scholar]
- de Win A. H., Worring M., Derksen J., Pierson E. S. Classification of organelle trajectories using region-based curve analysis. Cytometry. 1997 Oct 1;29(2):136–146. doi: 10.1002/(sici)1097-0320(19971001)29:2<136::aid-cyto6>3.3.co;2-5. [DOI] [PubMed] [Google Scholar]