Intracellular localisation of phytochrome in oat coleoptiles by electron microscopy |
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Authors: | V Speth V Otto E Schäfer |
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Institution: | (1) Institut für Biologie II, Universität Freiburg, Schänzlestraße 1, D-7800 Freiburg i.Br., Federal Republic of Germany |
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Abstract: | We have analysed the intracellular localisation of phytochrome in oat coleoptile cells by electron microscopy and confirm and extend light-microscopical findings of previous authors. We used indirect immuno-labeling with polyclonal antibodies against 60-KDa phytochrome from etiolated oat seedlings, and a gold-coupled second antibody, on ultrathin sections of LR-white-embedded material. In dark-grown seedlings, phytochrome-labeling is distributed diffusely throughout the cytoplasm. Organelles and membranes are not labeled. After photoconversion of the red-absorbing form of phytochrome to the far-red absorbing form (Pfr) (5-min red light; 660 nm), the label is sequestered uniquely in electron-dense areas within the cytoplasm. These areas are irregularly shaped, are often located in the vicinity of the vacuole, are not surrounded by a membrane, exclude cellular organelles and ribosomes and are not found in dark-grown material; an immediate 5-min farred light pulse after the red light does not cause these structures to disappear. After a dark period of 3–4 h following red-light irradiation, these electron-dense structures disappear together with any specific labeling. We suggest a Pfr-induced aggregation of an unknown, phytochrome-binding protein or proteins.Abbreviations
Pr and Pfr
phytochrome in its red and far-red absorbing form, respectively |
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Keywords: | Phytochrome localisation Avena Immunochemistry Electronmicroscopy |
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