Search results for "Protoplast"
showing 10 items of 55 documents
Clathrin-mediated constitutive endocytosis of PIN auxin efflux carriers in Arabidopsis.
2007
SummaryEndocytosis is an essential process by which eukaryotic cells internalize exogenous material or regulate signaling at the cell surface [1]. Different endocytic pathways are well established in yeast and animals; prominent among them is clathrin-dependent endocytosis [2, 3]. In plants, endocytosis is poorly defined, and no molecular mechanism for cargo internalization has been demonstrated so far [4, 5], although the internalization of receptor-ligand complexes at the plant plasma membrane has recently been shown [6]. Here we demonstrate by means of a green-to-red photoconvertible fluorescent reporter, EosFP [7], the constitutive endocytosis of PIN auxin efflux carriers [8] and their …
The Effect of Secretion on Lipids and their Distribution in Barley Aleurone Protoplasts
1988
Barley aleurone protoplasts, when exposed to Ga3 and Ca2+ synthesize and secrete the hydrolytic enzyme α -amylase (Bush et al., 1986). At the same time, protoplasts undergo important structural changes which reflect the elaboration of the membrane system involved in protein synthesis and secretion. The mobilization of lipid reserves may be a preliminar step which would provide energy as well as several components for the synthesis of membrane lipids.
Factors Influencing Digitalis Obscura Mesophyll Protoplast Development
1988
In a previous work (1), we found that a combination of liquid-over-agar-solidified MS (2) modified medium was superior to either all liquid or all solid medium for culture of Digitalis obscura L. mesophyll protoplasts. In order to achieve optimum culture conditions we now report on the influence of a different gelling agent (agarose) as well as the effect of several nutrient media on D. obscura mesophyll protoplasts development.
Transglutaminase activity is involved in Saccharomyces cerevisiae wall construction
2002
Transglutaminase activity, which forms the interpeptidic cross-link N(epsilon)-(gamma-glutamyl)-lysine, was demonstrated in cell-free extracts of Saccharomyces cerevisiae by incorporation of [(14)C]lysine into an exogenous acceptor, N,N'-dimethylcasein. Higher levels of the activity were present in the cell wall, which also contained endogenous acceptors. The enzyme activity in the wall was inhibited by cystamine, a known inhibitor of transglutaminase, and by EDTA, indicating a cation-dependent activity. After the endogenous wall acceptors were labelled radioactively by transglutaminase, extraction with SDS solubilized about 50% of the total radioactivity, while Zymolyase and chitinase each…
Cell Cycle in Potentially Dedifferentiating Cereal Mesophyll Protoplasts Cultured in vitro. I. Abnormalities in Cycle Kinetics
1993
Summary Protoplasts isolated from immature and mature mesophyll of wheat and oats were cultured in vitro . The potential progression from G1 (G0) to G2, through mitosis and cytokinesis was analysed. The degree and speed of progression through the cell cycle depended on the species and the state of maturity of the tissue from which the protoplasts were derived. In all the protoplast populations that were tested at least initiation of DNA synthesis was detected by labelling nuclei with the thymidine-analogue, bromodeoxyuridine (BrdU). Protoplasts derived from mature leaf tissue of wheat appeared to be recalcitrant to reach G2. Wheat protoplasts derived from immature leaf tissue appeared to pr…
Isolation and culture of grape vine cv. Chardonnay leaf protoplasts
1990
Experimental conditions were established that resulted in high yields and good viability of the protoplasts obtained from leaves of Vitis vinifera, cv. Chardonnay regenerated in vitro by somatic embryogenesis. The effect of factors of the culture medium and various environmental conditions upon the frequency of cell division has been examined, and a method of culture is described by which protoplasts were induced to begin division. Most protoplasts obtained in this way regenerated cell walls within the first few days and cell division occurred after 10 days of culture in a liquid medium. Some cells have divided two or even three times. Nevertheless, the cells did not continue dividing beyon…
Biogenesis of the Yeast Cell Wall
1984
Yeast cells are covered by a rigid structure that protects the protoplast from osmotic changes and gives the characteristic shape to the cell. Studies on the composition of the wall of several species of yeast and other fungi have shown that they contain mainly polysaccharides with minor amounts of other materials. A completely rigid and continuous wall, nevertheless, would render growth impossible because cell extension would be restricted, so that an equilibrium must exist between softening (partial degradation) of wall and incorporation of new material into free ends of the polymers. From these considerations, it seems clear that the walls must be structurally and enzymatically a complex…
Protoplasts fromPodospora anserina: Isolation, purification, and transformation
1985
Protoplasts fromPodospora anserina mycelium were produced using the commercially available enzyme Novozym 234. Different parameters involved in protoplast isolation were analyzed in order to establish optimal conditions, and protoplast production was notably increased. For the purification of protoplasts, several techniques based on both centrifugation and filtration were assayed, with filtration yielding the best results. Regeneration of protoplasts was studied on different media and osmostic stabilizers, and about 80% regeneration was obtained. The good physiological condition of the protoplasts produced with this method is demonstrated by the lack of cell wall and high regeneration rate …
Sorting signals in the cytosolic tail of membrane proteins involved in the interaction with plant ARF1 and coatomer.
2004
Summary In mammals and yeast, a cytosolic dilysine motif is critical for endoplasmic reticulum (ER) localization of type I membrane proteins. Retrograde transport of type I membrane proteins containing dilysine motifs at their cytoplasmic carboxy (C)-terminal tail involves the interaction of these motifs with the COPI coat. The C-terminal dilysine motif has also been shown to confer ER localization to type I membrane proteins in plant cells. Using in vitro binding assays, we have analyzed sorting motifs in the cytosolic tail of membrane proteins, which may be involved in the interaction with components of the COPI coat in plant cells. We show that a dilysine motif in the −3,−4 position (rel…
d-Alanyl-d-Alanine Carboxypeptidase in the Bacterial Form and L-Form of Proteus mirabilis
1975
Membranes of the bacterial form and the stable and unstable L-forms of Proteus mirabilis contain LD and DD-carboxypeptidase. The DD-carboxypeptidase is inhibited non-competitively by penicillin G. The enzyme of the bacterial form is highly penicillin-sensitive (Ki - 4 X 10(-9) M penicillin G). Inhibition is only partly reversible by treatment with penicillinase or by dialysis against buffer. In contrast, the DD-carboxypeptidase of the unstable L-form, grown in the presence of penicillin, is 175-fold less penicillin-sensitive (Ki = 7 X 10(7) M penicillin G). Inhibition is completely reversed by penicillinase or dialysis. After inhibition by penicillin and subsequent reactivation the penicill…