scholarly journals Coated Vesicle-Mediated Transport and Deposition of Vitellogenic Ferritin in the Rapid Growth Phase of Snail Oocytes

1982 ◽  
Vol 53 (1) ◽  
pp. 173-191 ◽  
Author(s):  
W. BOTTKE ◽  
I. SINHA ◽  
I. KEIL
Keyword(s):  
Growth Phase ◽  
Rapid Growth ◽  
Lymnaea Stagnalis ◽  
Follicle Cells ◽  
Coated Vesicle ◽  
Secretory Cells ◽  
Basal Region ◽  
Coated Pits ◽  
Iron Storage ◽  
Basement Lamina

The main yolk component in oocytes of the pulmonate freshwater snails Planorbarius corneus L. and Lymnaea stagnalis L. consists of the iron storage protein ferritin and iron-free apoferritin. Both compounds are deposited in the yolk in the form of large paracrystalloids, tubular structures and randomly dispersed particles. In addition, the plasm contains lysosome-like inclusions with depositions of haemosiderin. Haemosiderin is interpreted as the product of proteolytic degradation of ferritin. During the rapid growth phase of the oocytes vitellogenic ferritin is transported across the basement lamina and taken up by adsorptive endocytosis via coated pits and vesicles. Formation of yolk bodies occurs by fusion of ferritin-containing vacuoles and empty vesicles that are probably derived from the Golgi apparatus. Uptake of ferritin is restricted to the basal region of the oocyte. No involvement of the follicle cells in synthesis and deposition of ferritin could be detected. Secretory cells of the midgut gland are the most likely site of synthesis of vitellogenic ferritin. Under conditions of iron overload large masses of ferritin are encountered in the basement lamina of the oocytes. However, no significant increase in the uptake of ferritin could be observed. With the use of a tannic acid-glutaraldehyde fixation procedure a hitherto unobserved filamentous or rod-like material was detected inside the lamina and in coated pits. This material is probably also taken up by the oocytes and integrated into yolk platelets. Though ferritin is a rather unusual vitellogenic protein, the mode of its uptake and deposition in the oocyte plasm is highly reminiscent of that of typical hormone-induced vitellogenins in other animal groups.

scholarly journals Rapid Growth Phase of Ovum in the Guinea Fowl.

1996 ◽  
Vol 33 (5) ◽  
pp. 300-304
Author(s):  
Hiroshi OGAWA ◽  
Takehito KUWAYAMA ◽  
Katuhide TANAKA
Keyword(s):  
Growth Phase ◽  
Rapid Growth ◽  
Guinea Fowl

scholarly journals Multi-modal adaptor-clathrin contacts drive coated vesicle assembly

2021 ◽  
Author(s):  
Sarah M Smith ◽  
Gabrielle Larocque ◽  
Katherine M Wood ◽  
Kyle L Morris ◽  
Alan M Roseman ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Binding Sites ◽  
Potential Role ◽  
Fundamental Property ◽  
Structural Knowledge ◽  
Coated Vesicle ◽  
Functional Importance ◽  
Coated Pits ◽  
Interaction Sites ◽  
Cross Links

Clathrin-coated pits are formed by the recognition of membrane and cargo by the heterotetrameric AP2 complex and the subsequent recruitment of clathrin triskelia. A potential role for AP2 in coated-pit assembly beyond initial clathrin recruitment has not been explored. Clathrin binds the b2 subunit of AP2, and several binding sites on b2 and on the clathrin heavy chain have been identified, but our structural knowledge of these interactions is incomplete and their functional importance during endocytosis is unclear. Here, we analysed the cryo-EM structure of clathrin cages assembled in the presence of b2 hinge and appendage (b2HA) domains. We find that the b2-appendage binds in at least two positions in the cage, demonstrating that multi-modal binding is a fundamental property of clathrin-AP2 interactions. In one position, b2-appendage cross-links two adjacent terminal domains from different triskelia below the vertex. Functional analysis of b2HA-clathrin interactions reveals that endocytosis requires two clathrin interaction sites: a clathrin-box motif on the hinge and the ''sandwich site'' on the appendage, with the appendage ''platform site'' having less importance. From these studies and the work of others, we propose that b2-appendage binding to more than one clathrin triskelion is a key feature of the system and likely explains why clathrin assembly is driven by AP2.

scholarly journals AP-2/Eps15 Interaction Is Required for Receptor-mediated Endocytosis

1998 ◽  
Vol 140 (5) ◽  
pp. 1055-1062 ◽  
Author(s):  
Alexandre Benmerah ◽  
Christophe Lamaze ◽  
Bernadette Bègue ◽  
Sandra L. Schmid ◽  
Alice Dautry-Varsat ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Fusion Protein ◽  
Binding Sites ◽  
Fluorescent Protein ◽  
Coated Vesicle ◽  
Mutant Form ◽  
A431 Cells ◽  
Coated Pits ◽  
Receptor Mediated Endocytosis ◽  
Terminal Domain

We have previously shown that the protein Eps15 is constitutively associated with the plasma membrane adaptor complex, AP-2, suggesting its possible role in endocytosis. To explore the role of Eps15 and the function of AP-2/Eps15 association in endocytosis, the Eps15 binding domain for AP-2 was precisely delineated. The entire COOH-terminal domain of Eps15 or a mutant form lacking all the AP-2–binding sites was fused to the green fluorescent protein (GFP), and these constructs were transiently transfected in HeLa cells. Overexpression of the fusion protein containing the entire COOH-terminal domain of Eps15 strongly inhibited endocytosis of transferrin, whereas the fusion protein in which the AP-2–binding sites had been deleted had no effect. These results were confirmed in a cell-free assay that uses perforated A431 cells to follow the first steps of coated vesicle formation at the plasma membrane. Addition of Eps15-derived glutathione-S-transferase fusion proteins containing the AP-2–binding site in this assay inhibited not only constitutive endocytosis of transferrin but also ligand-induced endocytosis of epidermal growth factor. This inhibition could be ascribed to a competition between the fusion protein and endogenous Eps15 for AP-2 binding. Altogether, these results show that interaction of Eps15 with AP-2 is required for efficient receptor-mediated endocytosis and thus provide the first evidence that Eps15 is involved in the function of plasma membrane–coated pits.

scholarly journals Adaptor and Clathrin Exchange at the Plasma Membrane andtrans-Golgi Network

2003 ◽  
Vol 14 (2) ◽  
pp. 516-528 ◽  
Author(s):  
Xufeng Wu ◽  
Xiaohong Zhao ◽  
Rosa Puertollano ◽  
Juan S. Bonifacino ◽  
Evan Eisenberg ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Fluorescence Recovery After Photobleaching ◽  
Fluorescence Recovery ◽  
Coated Vesicle ◽  
Coated Pits ◽  
Trans Golgi Network ◽  
Rapid Exchange ◽  
Dynamic Structures ◽  
Golgi Network ◽  
Network Exchange

We previously demonstrated, using fluorescence recovery after photobleaching, that clathrin in clathrin-coated pits at the plasma membrane exchanges with free clathrin in the cytosol, suggesting that clathrin-coated pits are dynamic structures. We now investigated whether clathrin at the trans-Golgi network as well as the clathrin adaptors AP2 and AP1 in clathrin-coated pits at the plasma membrane and trans-Golgi network, respectively, also exchange with free proteins in the cytosol. We found that when the budding of clathrin-coated vesicle is blocked without significantly affecting the structure of clathrin-coated pits, both clathrin and AP2 at the plasma membrane and clathrin and AP1 at thetrans-Golgi network exchange rapidly with free proteins in the cytosol. In contrast, when budding of clathrin-coated vesicles was blocked at the plasma membrane or trans-Golgi network by hypertonic sucrose or K+ depletion, conditions that markedly affect the structure of clathrin-coated pits, clathrin exchange was blocked but AP2 at the plasma membrane and both AP1 and the GGA1 adaptor at the trans-Golgi network continue to rapidly exchange. We conclude that clathrin-coated pits are dynamic structures with rapid exchange of both clathrin and adaptors and that adaptors are able to exchange independently of clathrin when clathrin exchange is blocked.

Ultrastructural characteristics of the follicle cell-oocyte interface in the oogenesis of Ceratophrys cranwelli

Zygote ◽  
2002 ◽  
Vol 10 (2) ◽  
pp. 163-173 ◽  
Author(s):  
Evelina I. Villecco ◽  
Susana B. Genta ◽  
Alicia N. Sánchez Riera ◽  
Sara S. Sánchez
Keyword(s):  
Plasma Membrane ◽  
Granular Material ◽  
Gap Junctions ◽  
Close Contact ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Apical Surface ◽  
Coated Pits ◽  
Compact Zone ◽  
Vitelline Envelope

In this work we carried out an ultrastructural analysis of the cell interface between oocyte and follicle cells during the oogenesis of the amphibian Ceratophrys cranwelli, which revealed a complex cell-cell interaction. In the early previtellogenic follicles, the plasma membrane of the follicle cells lies in close contact with the plasma membrane of the oocyte, with no interface between them. In the mid-previtellogenic follicles the follicle cells became more active and their cytoplasm has vesicles containing granular material. Their apical surface projects cytoplasmic processes (macrovilli) that contact the oocyte, forming gap junctions. The oocyte surface begins to develop microvilli. At the interface both processes delimit lacunae containing granular material. The oocyte surface has endocytic vesicles that incorporate this material, forming cortical vesicles that are peripherally arranged. In the late previtellogenic follicle the interface contains fibrillar material from which the vitelline envelope will originate. During the vitellogenic period, there is an increase in the number and length of the micro- and macrovilli, which become regularly arranged inside fibrillar tunnels. At this time the oocyte surface exhibits deep crypts where the macrovilli enter, thus increasing the follicle cell-oocyte junctions. In addition, the oocyte displays coated pits and vesicles evidencing an intense endocytic activity. At the interface of the fully grown oocyte the fibrillar network of the vitelline envelope can be seen. The compact zone contains a fibrillar electron-dense material that fills the spaces previously occupied by the now-retracted microvilli. The macrovilli are still in contact with the surface of the oocyte, forming gap junctions.

scholarly journals Histochemical structure and immunolocalisation of the hyaluronan system in the dromedary oviduct

2016 ◽  
Vol 28 (7) ◽  
pp. 936 ◽  
Author(s):  
Omnia Mohey-Elsaeed ◽  
Waleed F. A. Marei ◽  
Ali A. Fouladi-Nashta ◽  
Abdel-Aleem A. El-Saba
Keyword(s):  
Epithelial Cells ◽  
Molecular Size ◽  
Blue Staining ◽  
Secretory Cells ◽  
Alcian Blue Staining ◽  
Basal Region ◽  
Epithelial Surface ◽  
Ciliated Epithelial Cells ◽  
Oviductal Fluid ◽  
Local Modulation

We investigated the local modulation of some histochemical properties of oviducts of the dromedary (Camelus dromedarius), focusing on the immnolocalisation of hyaluronic acid (HA) synthases (HAS2 and HAS3), hyaluronidases (HYAL2 and HYAL1) and the HA receptor CD44 in the ampulla and isthmus. Abundant acidic mucopolysaccharides (glycosaminoglycans) were detected by Alcian blue staining along the luminal surface of both ciliated and non-ciliated epithelial cells (LE). Staining for HAS2 was higher in the primary epithelial folds of the ampulla compared with the isthmus, especially in secretory cells, adluminal epithelial surface and supranuclear cell domain. HAS3 staining was stronger in the LE of the isthmus than ampulla. HYAL2 was detected in the LE in the ampulla and isthmus and was more intense in the adluminal projections of secretory cells. HYAL1 was weakly detected in the LE with no difference between the ampulla and isthmus. Strong CD44 immunostaining was present in the LE of the ampulla and isthmus. CD44 staining was higher in secretory cells than in ciliated epithelial cells and was higher in the supranuclear region than the basal region of the cytoplasm. In conclusion, we provide evidence that HA synthesis and turnover occur in the camel oviduct. Differences in HAS2 and HAS3 expression suggest regional differences in the molecular size of HA secreted in oviductal fluid that may influence oviduct–gamete interaction in the camel.

scholarly journals Immunofluorescent localization of 100K coated vesicle proteins.

1986 ◽  
Vol 102 (1) ◽  
pp. 48-54 ◽  
Author(s):  
M S Robinson ◽  
B M Pearse
Keyword(s):  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Limited Proteolysis ◽  
Bovine Brain ◽  
Coated Vesicles ◽  
Cell Protein ◽  
Coated Vesicle ◽  
Coated Pits ◽  
Double Labeling ◽  
Vesicle Proteins

A family of coated vesicle proteins, with molecular weights of approximately 100,000 and designated 100K, has been implicated in both coat assembly and the attachment of clathrin to the vesicle membrane. These proteins were purified from extracts of bovine brain coated vesicles by gel filtration, hydroxylapatite chromatography, and preparative SDS PAGE. Peptide mapping by limited proteolysis indicated that the polypeptides making up the three major 100K bands have distinct amino acid sequences. When four rats were immunized with total 100K protein, each rat responded differently to the different bands, although all four antisera cross-reacted with the 100K proteins of human placental coated vesicles. After affinity purification, two of the antisera were able to detect a 100K band on blots of whole 3T3 cell protein and were used for immunofluorescence, double labeling the cells with either rabbit anti-clathrin or with wheat germ lectin as a Golgi apparatus marker. Both antisera gave staining that was coincident with anti-clathrin, with punctate labeling of the plasma membrane and perinuclear Golgi apparatus labeling. Thus, the 100K proteins are present on endocytic as well as Golgi-derived coated pits and vesicles. The punctate patterns were nearly identical with anti-100K and anti-clathrin, indicating that when vesicles become uncoated, the 100K proteins are removed as well as clathrin. One of the two antisera gave stronger plasma membrane labeling than Golgi apparatus labeling when compared with the anti-clathrin antiserum. The other antiserum gave stronger Golgi apparatus labeling. Although we have as yet no evidence that these two antisera label different proteins on blots of 3T3 cells, they do show differences on blots of bovine brain 100K proteins. This result, although preliminary, raises the possibility that different 100K proteins may be associated with different pathways of membrane traffic.

Effects of temperature, drought, and gibberellin A4/7, and timing of treatment, on flowering in potted Piceaengelmannii and Piceaglauca grafts

1988 ◽  
Vol 18 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Stephen D. Ross
Keyword(s):  
Heat Treatment ◽  
Growth Phase ◽  
Rapid Growth ◽  
Cultural Practices ◽  
Heat Treatments ◽  
Cone Production ◽  
Treatment Regimes ◽  
Effects Of Temperature ◽  
Timing Of Treatment ◽  
Spray Applications

Four experiments conducted over 2 years on potted 4- to 7-year-old Piceaengelmannii and 3-year-old Piceaglauca grafts compared the effectiveness of different temperature, drought, and gibberellin A4/7 treatment regimes for promotion of flowering. With the exception of one study in which trees were not properly preconditioned, heat treatment within a polyethylene–covered house (polyhouse) promoted profuse female and male flowering in previously root-pruned P. engelmannii grafts. The optimal daytime temperature of 22–25 °C in the polyhouse was well below the 30 °C temperature for Piceaabies suggested in the literature. Timing of heat treatment was critical. Few trees produced seed or pollen cones if moved indoors before the new shoots were at least 80% elongated, with 85–95% elongation being optimal. Drought also promoted flowering but only if applied outdoors while shoots were actively elongating. Response to these cultural practices was further enhanced by spray applications of gibberellin A4/7 during the rapid growth phase. Younger P. glauca grafts that were not root-pruned or sprayed with gibberellin A4/7 failed to respond to early drought and late heat treatments, but did so the following year when these adjunct treatments were given. Response of P. engelmannii grafts to retreatment indicates that alternate-year induction, with a year's rest for cone maturation and vegetative replenishment of shoots turned reproductive, is practical and will result in sustained abundant cone production in potted trees.

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