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Procedures are described for obtaining and handling ribboned epon sections 0.3–2 μ thick for light microscopy, and for the cytological application of two intense acid dyes, Aniline Blue Black and Coomassie Brilliant Blue R 250. The technique allows precise localization of proteins and some other materials, and, because the sections are ribboned, facilitates(More)
Although the enucleate conducting cells of the phloem are incapable of protein synthesis, phloem exudates characteristically contain low concentrations of soluble proteins. The role of these proteins and their movement into and out of the sieve tubes poses important questions for phloem physiology and for cell-to-cell protein movement via plasmodesmata. The(More)
All flowering plants produce S-methylmethionine (SMM) from Met and have a separate mechanism to convert SMM back to Met. The functions of SMM and the reasons for its interconversion with Met are not known. In this study, by using the aphid stylet collection method together with mass spectral and radiolabeling analyses, we established that l-SMM is a major(More)
A variety of fluorescent tracers and proteins were injected via severed aphid stylets into the sieve tubes of wheat (Triticum aestivum L.) grains to evaluate the dimensions of plasmodesmal channels involved in sieve element/companion cell (SE/CC) unloading and post-phloem transport. In the post-phloem pathway, where diffusion is the predominant mode of(More)
An analysis of the entrance and discharge of the pollen tube into the embryo sac of Gossypium hirsutum was made with the light and electron microscopes. The following sequence of events is seen in cotton: 1. One of the two synergids begins to degenerate following pollination but before the pollen tube reaches the embryo sac. This degeneration is marked by(More)
Severed aphid stylets were used to follow the kinetics of sieve tube turgor and osmotic pressure (pi) responses following step changes in water potential applied to the cambial surface of willow (Salix exigua Nutt.) bark strips. The kinetics of the turgor response were monitored with a pressure transducer. In separate experiments, the kinetics of the pi(More)
Four species of the genus Flaveria, namely F. anomala, F. linearis, F. pubescens, and F. ramosissima, were identified as intermediate C(3)-C(4) plants based on leaf anatomy, photosynthetic CO(2) compensation point, O(2) inhibition of photosynthesis, and activities of C(4) enzymes. F. anomala and F. ramosissima exhibit a distinct Kranz-like leaf anatomy,(More)
Soybean (Glycine max cv. Bragg) petiolar tissue containing translocated (14)C-sucrose was quick frozen, freeze-substituted in acetone or propylene oxide and embedded in Epon. This procedure allowed cytological observations on sieve elements whose functional condition could be verified by microautoradiography. Sieve elements and companion cells were(More)
The ultrastructure and composition of cotton (Gossypium hirsutum) pollen, exclusive of the wall, was examined immediately before and after germination. The pollen grain before germination consists of two parts: the outer layer and a central core. The outer layer contains large numbers of mitochondria and dictyosomes as well as endoplasmic reticulum (ER).(More)