scholarly journals Trafficking and Sequestration of Anthocyanins

2008 ◽  
Vol 3 (8) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Erich Grotewold ◽  
Kevin Davies
Keyword(s):  
Endoplasmic Reticulum ◽  
Central Vacuole ◽  
Cytoplasmic Surface ◽  
Large Central Vacuole ◽  
Frequent Localization

Flavonoids are synthesized on the cytoplasmic surface of the endoplasmic reticulum (ER). As is the case for several other phytochemicals, anthocyanins and other products of the pathway often accumulate in the large central vacuole. This review summarizes recent findings on the possible mechanisms by which flavonoids traffic between the ER and the vacuole, and discusses the frequent localization of anthocyanins in sub-vacuolar structures with variable characteristics.

Ultrastructure of laticifers in redifferentiated organs on callus from Papaver somniferum (Papaveraceae)

1979 ◽  
Vol 57 (6) ◽  
pp. 675-685 ◽  
Author(s):  
Craig L. Nessler ◽  
Paul G. Mahlberg
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Cross Section ◽  
Papaver Somniferum ◽  
Reticulum Cell ◽  
Central Vacuole ◽  
Conspicuous Feature ◽  
Intact Plants ◽  
Meristematic Region ◽  
Large Central Vacuole

Callus was initiated from seedling hypocotyls and mature stems of Papaver somniferum and maintained in culture. The ultrastructure of callus cells resembled parenchyma of intact plants, their most conspicuous feature being a large central vacuole. Meristemoids were formed at random on the surface of calli transferred to the appropriate medium. In cross section, meristemoids appeared as an inner meristematic region surrounded by several layers of concentrically arranged cells. Cells of meristemoids were smaller, more densely cytoplasmic, and more compactly arranged compared with callus. Roots and shoots induced to form from callus possessed cells that were morphologically and developmentally similar to laticifers in intact plants. Laticifers in redifferentiated organs, like those in intact plants, contained numerous capped vesicles that are apparently derived from stacked endoplasmic reticulum. Cell wall perforations between adjacent laticifer elements in redifferentiated organs developed by the gradual, simultaneous thinning of walls at the perforation sites.

The polypeptides of rat liver nuclear envelope. II. Comparison of rat liver nuclear membrane polypeptides with those of the rough endoplasmic reticulum

1980 ◽  
Vol 43 (1) ◽  
pp. 269-277
Author(s):  
J.C. Richardson ◽  
A.H. Maddy
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Relative Proportion ◽  
Membrane System ◽  
Membrane Systems ◽  
Nuclear Membranes ◽  
Cytoplasmic Surface ◽  
Triton X

Nuclear envelopes are separated into pore-lamina and membrane sub-fractions by extraction in 2.0% Triton X-100 followed by pelleting of the pore-laminae. The polypeptides of these subfractions are then compared with those from isolated rough endoplasmic reticulum. The dispositions of individual polypeptides in the cytoplasmic surface of nuclear envelopes and rought endoplasmic reticulum were studied by lactoperoxidase-catalysed iodination. These studies show that although the nuclear membranes exhibit several homologies with the Triton-soluble polypeptides of the rough endoplasmic reticulum the relative proportion of individual polypeptides within the two systems are very largely different. The cytoplasmic surfaces of the 2 membrane systems show only 2 obvious homologies at 105 000 and 15 000 mol. wt and the overall impression is that, at least in rat liver, the outer nuclear membrane is very substantially differentiated from rough endoplasmic reticulum. It is concluded that the nuclear membranes may not be regarded as a mere continuum of the endoplasmic reticulum, but should be seen as a highly specialized membrane system in their own right.

scholarly journals Biosynthesis of lipoprotein: location of nascent apoAI and apoB in the rough endoplasmic reticulum of chicken hepatocytes

1992 ◽  
Vol 117 (6) ◽  
pp. 1161-1169 ◽  
Author(s):  
JL Dixon ◽  
R Chattapadhyay ◽  
T Huima ◽  
CM Redman ◽  
D Banerjee
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Microscopic Examination ◽  
Microsomal Membrane ◽  
Golgi Cell ◽  
Lipoprotein Particles ◽  
Morphological Findings ◽  
Cytoplasmic Surface ◽  
Luminal Side ◽  
Cell Fractions

Our previous studies showed that in hepatic RER of young chickens, nascent apoAI is not associated with lipoprotein particles and only becomes part of these lipoprotein structures in the Golgi. In this study, we have used three different methodologies to determine the locations of apoAI and apoB in the RER and compared them to that of albumin. Immunoelectron microscopic examination of the RER cell fractions showed that both apoAI and apoB were associated only with the RER membrane whereas albumin was located both within the lumen and on the limiting membrane of the vesicles. To examine the possibility of membrane integration of nascent apoAI and apoB in the RER, we administered L-[3H]leucine to young chickens for 10 min, isolated RER, treated this cell fraction with buffers of varying pH, and measured the release of radioactive albumin, apoAI, and apoB. The majority of nascent apoAI (64%), nascent apoB (100%), and nascent albumin (97%) was released from RER vesicles at pH 11.2, suggesting that, like albumin, apolipoproteins are not integrated within the membrane. To determine if nascent apoproteins are exposed to the cytoplasmic surface, we administered L-[3H]leucine to young chickens and at various times isolated RER and Golgi cell fractions. Radioactive RER and Golgi cell fractions were treated with exogenous protease and the percent of nascent apoAI and apoB accessible to proteolysis was determined and compared to that of albumin. At 5, 10, and 20 min of labeling, 35-56% of nascent apoAI and 60-75% of apoB in RER were degraded, while albumin was refractive to this treatment. At all times both apolipoproteins and albumin present in Golgi cell fractions were protected from proteolysis. These biochemical and morphological findings indicate that apoAI and apoB are associated with the rough microsomal membrane and are partially exposed to the cytoplasmic surface at early stages of secretion. They may later enter the luminal side of the ER and, on entering the Golgi, form lipoprotein particles.

Ultrastructure of mimosa leaflet and pulvinule

1978 ◽  
Vol 36 (2) ◽  
pp. 422-423
Author(s):  
V. A. Stein-Margolina
Keyword(s):  
Thin Layer ◽  
Ruthenium Red ◽  
Central Vacuole ◽  
Lower Wall ◽  
Mimosa Pudica ◽  
Lower Zone ◽  
Lower Epidermis ◽  
Before And After ◽  
Large Central Vacuole ◽  
Light Stimuli

The ultrastructure of leaflet and tertiary pulvini (pulvinule) of the sensitive plant, Mimosa pudica L., as well as the distribution of ATPase were studied before and after stimulation.There are two zones in the majority of upper epidermis cells of the leaflet (Fig. 1). The upper zone contains a thin layer of cytoplasma, a large central vacuole and much tannin. The lower zone of these cells is electron-transparent and has a lens-like shape. It is filled with fibrillar-foamy material (Fig. 2). “The foam” fibrills are 30-100 Å in diameter. “The foam” is stained with ruthenium red and is supposed to be a mucilaginous inner (lower) wall of the epidermal cell. The cells of the lower epidermis of the leaflet and the pulvinule epidermis do not contain “the foam”. The lens-shaped foamy material might focus light, promote its reception and transfer the light stimuli within the leaflets and pulvini, thus regulating the heliotropic and nyctinastic position of the leaf itself.

scholarly journals Folding of Active β-Lactamase in the Yeast Cytoplasm before Translocation into the Endoplasmic Reticulum

1998 ◽  
Vol 9 (4) ◽  
pp. 817-827 ◽  
Author(s):  
Eija Paunola ◽  
Taina Suntio ◽  
Eija Jämsä ◽  
Marja Makarow
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Disulfide Formation ◽  
Cytoplasmic Surface ◽  
C Terminus ◽  
Unfolded State ◽  
Partially Unfolded

Polypeptides targeted to the yeast endoplasmic reticulum (ER) posttranslationally are thought to be kept in the cytoplasm in an unfolded state by Hsp70 chaperones before translocation. We show here that Escherichia coli β-lactamase associated with Hsp70, but adopted a native-like conformation before translocation in living Saccharomyces cerevisiae cells. β-Lactamase is a globular trypsin-resistant molecule in authentic form. For these studies, it was linked to the C terminus of a yeast polypeptide Hsp150Δ, which conferred posttranslational translocation and provided sites for O-glycosylation. We devised conditions to retard translocation of Hsp150Δ-β-lactamase. This enabled us to show by protease protection assays that an unglycosylated precursor was associated with the cytoplasmic surface of isolated microsomes, whereas a glycosylated form resided inside the vesicles. Both proteins were trypsin resistant and had similar β-lactamase activity andK m values for nitrocefin. The enzymatically active cytoplasmic intermediate could be chased into the ER, followed by secretion of the activity to the medium. Productive folding in the cytoplasm occurred in the absence of disulfide formation, whereas in the ER lumen, proper folding required oxidation of the sulfhydryls. This suggests that the polypeptide was refolded in the ER and consequently, at least partially unfolded for translocation.

Fine structure of latent infections by Rhabdocline parkeri on Douglas-fir, with observations on uninfected epidermal cells

1988 ◽  
Vol 66 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Jeffrey K. Stone
Keyword(s):  
Epidermal Cell ◽  
Condensed Tannins ◽  
Douglas Fir ◽  
Epidermal Cells ◽  
Central Vacuole ◽  
Direct Penetration ◽  
Large Central Vacuole ◽  
Epidermal Cell Wall ◽  
Intracellular Infections ◽  
Needle Senescence

Rhabdocline parkeri Sherwood-Pike, Stone, & Carroll, an endophyte of Douglas-fir, infects healthy foliage by direct penetration of the host epidermal cell wall. Penetration is accomplished by a very fine penetration hypha. Intracellular infections are established in a single epidermal cell and result in the death of the cell. Haustoria lacking neckbands are produced from the intracellular hyphae at the onset of needle senescence. The intracellular hyphae contain large quantities of stored lipid and numerous mitochondria and peroxisomes. Although not growing, the hyphae appear to be metabolically active. Douglas-fir epidermal cells are alive at maturity and contain rudimentary chloroplasts. Small quantities of lipids and starch are present in the healthy epidermal cells. The large central vacuole of the epidermal cells contains primarily condensed tannins and tannin precursors.

scholarly journals APPARENT VIOLATIONS OF THE ALL-OR-NONE LAW IN RELATION TO POTASSIUM IN THE PROTOPLASM

1954 ◽  
Vol 37 (6) ◽  
pp. 813-824
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Thin Layer ◽  
Outer Surface ◽  
External Solution ◽  
Central Vacuole ◽  
Total Potential ◽  
Inner Surface ◽  
Large Central Vacuole ◽  
Aqueous Layer

The protoplasm of Nitella forms a thin layer surrounding a large central vacuole filled with sap. At the inner surface of the protoplasm is a non-aqueous layer called Y and at the outer surface is a similar layer called X. At each of these layers there is a potential due to the diffusion of KCl in contact with the layer. We thus have P = PX + PY in which P is the total potential, PX is the potential at X, and PY the potential at Y. We assume that when stimulation occurs PY disappears and PX remains unaltered. The loss of part of the potential therefore involves no violation of the all-or-none law since the Y layer loses all of its potential and the X layer loses nothing. If the concentration of KCl in the external solution and in the sap is known the concentration in the protoplasm can be calculated at each stimulation by measuring the height of the spike.

scholarly journals Genes required for completion of import of proteins into the endoplasmic reticulum in yeast.

1984 ◽  
Vol 98 (1) ◽  
pp. 44-53 ◽  
Author(s):  
S Ferro-Novick ◽  
W Hansen ◽  
I Schauer ◽  
R Schekman
Keyword(s):  
Endoplasmic Reticulum ◽  
Carboxypeptidase Y ◽  
Restrictive Temperature ◽  
Cell Fractionation ◽  
Permissive Temperature ◽  
Cytoplasmic Surface ◽  
Protected Fragment ◽  
Triton X ◽  
Secretory Enzyme ◽  
Er Membrane

Yeast secretory mutants sec53 and sec59 define a posttranslational stage in the penetration of glycoprotein precursors into the endoplasmic reticulum (ER). In the previous report we showed that at the restrictive temperature (37 degrees C) these mutants accumulate enzymatically inactive and incompletely glycosylated forms of the secretory enzyme invertase and the vacuolar enzyme carboxypeptidase Y. Cell fractionation experiments reveal that these precursor forms remain firmly bound to the ER membrane. However, upon return to the permissive temperature (24 degrees C), the invertase precursors are glycosylated, become partially active, and are secreted. Thermoreversible conversion does not require protein synthesis, but does require energy. In contrast to the effect of these mutations, inhibition of oligosaccharide synthesis with tunicamycin at 37 degrees C causes irreversible accumulation of unglycosylated invertase. The effect of the drug is exaggerated by high temperature since unglycosylated invertase synthesized in the presence of tunicamycin at 25 degrees C is secreted. A portion of the invertase polypeptide accumulated at 37 degrees C is preserved when membranes from sec53 and sec59 are treated with trypsin. In the presence of Triton X-100 or saponin, the invertase is degraded completely. The protected fragment appears to represent a portion of the invertase polypeptide that is embedded in or firmly associated with the ER membrane. This association may develop early during the synthesis of invertase, so that in the absence of translocation, some of the completed polypeptide chain remains exposed on the cytoplasmic surface of the ER.

The development of cells in the coenocytic endosperm of the African blood lily Haemanthus Katherinae

1978 ◽  
Vol 56 (5) ◽  
pp. 483-501 ◽  
Author(s):  
William Newcomb
Keyword(s):  
Embryo Sac ◽  
Transfer Cell ◽  
Central Vacuole ◽  
Free Wall ◽  
Cell Type ◽  
Wall Ingrowths ◽  
Stage Of Development ◽  
Cellular Endosperm ◽  
Free Cells ◽  
Large Central Vacuole

The endosperm of the African blood lily Haemanthus Katherinae Bak. follows the helobial pattern of development in which two chambers of endosperm are formed. In the earliest observed stage of development a large micropylar chamber and a smaller dome-shaped chalazal chamber of endosperm are present. Both are coenocytic and contain wall ingrowths of the transfer cell type along the embryo sac wall. Freely growing walls grow centripetally from the embryo sac wall, branch, and eventually meet, forming a layer of cells along the embryo sac wall. This process occurs first in the micropylar chamber. After four or more layers of endosperm cells are present, phragmoplasts form in association with karyokinesis and give rise to cross walls situated between the freely growing walls. When 10 or more layers of endosperm cells are present, free wall-less cells are present in the central vacuole near the edge of the cellular endosperm of the micropylar chamber. The free cells originate from mitosis of nuclei at the inner wall-less edge of the endosperm and the subsequent pinching off and release of the free cells into the large central vacuole. The free cells may undergo karyokinesis and become binucleate. The chalazal chamber of endosperm also becomes cellular by means of freely growing walls.

Sign in / Sign up

Export Citation Format

Share Document