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Families of papain- and legumain-like cysteine proteinases (CPR) were found in Vicia seeds. cDNAs and antibodies were used to follow organ specificity and the developmental course of CPR-specific mRNAs and polypeptides. Four papain-like cysteine proteinases (CPR1, CPR2, proteinase A and CPR4) from vetch seeds ( Vicia sativa L.) were analysed. CPR2 and its mRNA were already found in dry embryonic axes. CPR1 was only detected there during early germination. Both CPR1 and CPR2 strongly increased later during germination. In cotyledons, both CPR1 and CPR2 were only observed one to two days later than in the axis. Proteinase A was not found in axes. In cotyledons it could only be detected several days after seeds had germinated. CPR4 mRNA and polypeptide were already present in embryonic axes and cotyledons during seed maturation and decreased in both organs during germination. Purified CPR1, CPR2 and proteinase A exhibited partially different patterns of globulin degradation products in vitro. Although the cDNA-deduced amino acid sequence of the precursor of proteinase A has an N-terminal signal peptide, the enzyme was not found in vacuoles whereas the other papain-like CPRs showed vacuolar localization. Four different legumain-like cysteine proteinases (VsPB2, proteinase B, VnPB1 and VnPB2) of Vicia species were analysed. Proteinase B and VnPB1 mRNAs were detected in cotyledons and seedling organs after seeds had germinated. Proteinase B degraded globulins isolated from mature vetch seeds in vitro. VsPB2 and proteinase B are localized to protein bodies of maturing seeds and seedlings, respectively, of V. sativa. Like VsPB2 from V. sativa, also VnPB2 of V. narbonensis corresponds to vacuolar processing enzymes (βVPE). Based on these results different functions in molecular maturation and mobilization of storage proteins could be attributed to the various members of the CPR families. [ABSTRACT FROM AUTHOR]

Protoplasts were prepared from cells of Chlorella saccharophila by treatment with a mixture of pectinase and cellulase. The yield of protoplasts is dependent upon the culture conditions prior to cell wall digestion. In thin section chemically-fixed protoplasts were without wall remnants at the surface of the plasma membrane. Of particular interest is the relationship between the Golgi apparatus and a nuclear envelope-endoplasmic reticulum continuum. Protoplasts have a photosynthetic capacity lying between 70 and 80% of that of normal cells, but show the same response towards CO concentration and DCMU inhibition. Protoplasts also respond to changes in the osmolarity of the surrounding medium in accordance with the Boylevan't Hoff equation as if they are an osmometer. The nonosmotic volume (NOV) was calculated. [ABSTRACT FROM AUTHOR]

Lucifer yellow CH (LY) uptake into intact leaves of Commelina communis has been studied with conventional fluorescence microscopy as well as confocal laser scanning microscopy. LY, a highly fluorescent tracer for apoplastic transport in plants and fluid phase endocytosis in animal cells, accumulates in the vacuole of leaf cells. However, considerable differences in the ability to take up LY were observed among the various cell types. Mesophyll cells take up large amounts of the dye whereas epidermal cells, including guard and subsidiary cells, showed no fluorescence in their vacuoles. An exception to this are trichome cells which show considerable accumulation of LY. When introduced into the cytoplasm of mesophyll protoplasts of C. communis by means of a patch-clamp pipette, LY does not enter the vacuole. This supports the contention that exogenous LY can only gain access to the vacuole via endocytosis. Differences in the capacity for LY uptake may therefore reflect differences in endocytotic activity. [ABSTRACT FROM AUTHOR]

The localization of α-amylase (EC 3.2.1.1) in barley ( Hordeum vulgare L. cv Himalaya) aleurone protoplasts was studied using electron microscope immunocytochemistry. Antibodies were raised against total barley α-amylase, i.e., α-amylase containing both highisoelectric point (high-pI) and low-pI isoforms, as well as against purified high- and low-pI isoforms. All antibodies localized α-amylase to the endoplasmic reticulum (ER) and Golgi apparatus (GApp) of the aleurone cell, and various controls showed that the labeling was specific for α-amylase. Labeling of protein bodies and spherosomes, which are the most abundant organelles in this cell, was very low. There was no evidence that α-amylase isoforms were differentially distributed within different compartments of the endomembrane system. Rather, both high- and low-pI isoforms showed the same pattern of distribution in ER and in the cis, medial, and transregions of the GApp. We conclude that in the Himalaya cultivar of barley, all isoforms of α-amylase are transported to the plasma membrane via the GApp. [ABSTRACT FROM AUTHOR]

London Resin (LR) White a hydrophilic embedding medium for immunocytochemistry, can be polymerized in a commercial microwave oven in seven minutes using the chemical accelerator benzoyl peroxide. In order to minimize the effects of heating, the polymerization vessel was maintained in an ice bath. We demonstrate that this procedure does not affect the antigenicity of either barley aleurone nuclease or of the catalytic and regulatory subunits of rat parotid cAMP-dependent protein kinase. [ABSTRACT FROM AUTHOR]