Substructure of freeze-substituted plasmodesmata |
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Authors: | B Ding R Turgeon M V Parthasarathy |
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Institution: | (1) Section of Plant Biology, Division of Biological Sciences, Cornell University, 14853 Ithaca, NY, USA;(2) Present address: Department of Botany, University of California, Davis, California, USA |
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Abstract: | Summary The substructure of plasmodesmata in freeze-substituted tissues of developing leaves of the tobacco plant (Nicotiana tabacum L. var. Maryland Mammoth) was studied by high resolution electron microscopy and computer image enhancement techniques. Both the desmotubule wall and the inner leaflet of the plasmodesmatal plasma membrane are composed of regularly spaced electron-dense particles approximately 3 nm in diameter, presumably proteinaceous and embedded in lipid. The central rod of the desmotubule is also particulate. In plasmodesmata with central cavities, spoke-like extensions are present between the desmotubule and the plasma membrane in the central cavity region. The space between the desmotubule and the plasma membrane appears to be the major pathway for intercellular transport through plasmodesmata. This pathway may be tortuous and its dimensions could be regulated by interactions between desmotubule and plasma membrane particles.Abbreviations ER
endoplasmic reticulum
- PJF
propane jet freezing
- HPF
high pressure freezing
- CRT
cathode ray tube
- IP3
inositoltrisphosphate |
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Keywords: | Freeze-substitution High-pressure freezing Intercellular transport Nicotiana tabacum Plasmodesmata Propane-jet freezing |
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