A decay of gap junctions in association with cell differentiation of neural retina in chick embryonic development

1976 ◽  
Vol 22 (3) ◽  
pp. 585-596
Author(s):  
H. Fujisawa ◽  
H. Morioka ◽  
K. Watanabe ◽  
H. Nakamura
Keyword(s):  
Cell Differentiation ◽  
Gap Junctions ◽  
Neural Retina ◽  
Chick Embryos ◽  
Cell Surfaces ◽  
Retinal Cells ◽  
Ultrastructural Studies ◽  
Stage Of Development ◽  
Pigmented Epithelium ◽  
Membrane Region

Ultrastructural studies of thin-sectioned and freeze-cleaved materials were performed on developing retinal tissues of 3- to 9-day-old chick embryos to clarify the junctional structures between neural retinal cells and between neural retinal cells and cells of the pigmented epithelium. Frequency, size and position of gap junctions in developing neural retina are different at each stage of development. In 3-day-old embryos, some cells adhere to each other by gap junctions immediately below the outer limiting membrane of neural retinae. The size and number of gap junctions increase remarkably during 5–6 days of incubation. In this period of development, well developed gap junctions consisting of subcompartments of intramembrane particles are found between cell surfaces at both the outer limiting membrane region and the deeper portion of the neural retina. Gap junctions disappear thereafter, and at 7-5 days of incubation, small gap junctions are predominant between cell surfaces at the outer limiting membrane region, while the frequency of gap junctions in the deeper portion is very low. At 9 days of incubation, gap junctions are rarely found. Typical gap junctions are always found between neural retinal cells and those of the pigmented epithelium in embryos up to 7-5 days of incubation. Tight junctions are not found in the neural retina or between neural retina and pigmented epithelium throughout the stages examined.

Fibroblast growth factors are necessary for neural retina but not pigmented epithelium differentiation in chick embryos

Development ◽  
1997 ◽  
Vol 124 (4) ◽  
pp. 805-816 ◽  
Author(s):  
C. Pittack ◽  
G.B. Grunwald ◽  
T.A. Reh
Keyword(s):  
Growth Factors ◽  
Neutralizing Antibodies ◽  
Pigment Epithelium ◽  
Fibroblast Growth Factors ◽  
Neural Retina ◽  
Chick Embryos ◽  
Fibroblast Growth ◽  
Developmental Potential ◽  
Pigmented Epithelium ◽  
Optic Vesicles

During eye development, optic vesicles evaginate laterally from the neural tube and develop into two bilayered eye cups that are composed of an outer pigment epithelium layer and an inner neural retina layer. Despite their similar embryonic origin, the pigment epithelium and neural retina differentiate into two very distinct tissues. Previous studies have demonstrated that the developmental potential of the pigmented epithelial cells is not completely restricted; until embryonic day 4.5 in chick embryos, the cells are able to switch their phenotype and differentiate into neural retina when treated with fibroblast growth factors (FGF) (Park, C. M., and Hollenberg, M. J. (1989). Dev. Biol. 134, 201–205; Pittack, C., Jones, M., and Reh, T. A. 1991). Development 113, 577–588; Guillemot, F. and Cepko, C. L. (1992). Development 114, 743–754). These studies motivated us to test whether FGF is necessary for neural retina differentiation during the initial stages of eye cup development. Optic vesicles from embryonic day 1.5 chick were cultured for 24 hours as explants in the presence of FGF or neutralizing antibodies to FGF2. The cultured optic vesicles formed eye cups that contained a lens vesicle, neural retina and pigmented epithelium, based on morphology and expression of neural and pigmented epithelium-specific antigens. Addition of FGF to the optic vesicles caused the presumptive pigmented epithelium to undergo neuronal differentiation and, as a consequence, a double retina was formed. By contrast, neutralizing antibodies to FGF2 blocked neural differentiation in the presumptive neural retina, without affecting pigmented epithelial cell differentiation. These data, along with evidence for expression of several FGF family members and their receptors in the developing eye, indicate that members of the FGF family may be required for establishing the distinction between the neural retina and pigmented epithelium in the optic vesicle.

scholarly journals Quantification of ganglioside GM1 synthetase activity on intact chick neural retinal cells.

1982 ◽  
Vol 93 (1) ◽  
pp. 76-81 ◽  
Author(s):  
M Pierce
Keyword(s):  
Cell Surface ◽  
Neural Retina ◽  
Synthetase Activity ◽  
Chick Embryos ◽  
Uridine Diphosphate ◽  
Ganglioside Gm1 ◽  
Intact Cells ◽  
Retinal Cells ◽  
Dorsoventral Axis ◽  
Specific Activities

Neural retinal cells from 9-d-old chick embryos were assayed for uridine diphosphate (UDP)-galactose:ganglioside GM2 galactosyltransferase, or GM1 synthetase, activity using the oligosaccharide fragment of GM2, oligo-GM2, oligo-GM2, as the exogenous acceptor. The results demonstrated that this enzyme activity was present on the external surfaces of intact cells. Little difference between the specific activities of cell surface GM1 synthetase could be detected when cells derived from dorsal and ventral segments of the neural retina were compared. These results suggested that this cell-surface enzyme was not present in a concentration gradient along the dorsoventral axis of the neural retina.

Electron microscopy of endocardial cell populations

1978 ◽  
Vol 36 (2) ◽  
pp. 486-487
Author(s):  
T. G. Sarphie ◽  
C. R. Comer ◽  
D. J. Allen
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Cellular Transformation ◽  
Cell Populations ◽  
Cell Surfaces ◽  
Kb Cells ◽  
Dna Viruses ◽  
Cell Cycles ◽  
Ultrastructural Studies ◽  
Endocardial Cell

Previous ultrastructural studies have characterized surface morphology during norma cell cycles in an attempt to associate specific changes with specific metabolic processes occurring within the cell. It is now known that during the synthetic ("S") stage of the cycle, when DNA and other nuclear components are synthesized, a cel undergoes a doubling in volume that is accompanied by an increase in surface area whereby its plasma membrane is elaborated into a variety of processes originally referred to as microvilli. In addition, changes in the normal distribution of glycoproteins and polysaccharides derived from cell surfaces have been reported as depreciating after cellular transformation by RNA or DNA viruses and have been associated with the state of growth, irregardless of the rate of proliferation. More specifically, examination of the surface carbohydrate content of synchronous KB cells were shown to be markedly reduced as the cell population approached division Comparison of hamster kidney fibroblasts inhibited by vinblastin sulfate while in metaphase with those not in metaphase demonstrated an appreciable decrease in surface carbohydrate in the former.

SEM localization of cell-surface-associated fibronectin in the cranium of chick embryos utilizing immunolatex microspheres

Development ◽  
1984 ◽  
Vol 80 (1) ◽  
pp. 175-195
Author(s):  
Stephen Meier ◽  
Christopher Drake
Keyword(s):  
Basement Membranes ◽  
Chick Embryos ◽  
Preimmune Serum ◽  
Fluorescent Staining ◽  
Cell Surfaces ◽  
Cell Soma ◽  
Rabbit Igg ◽  
Neural Ectoderm ◽  
Cranial Neural Crest Cells ◽  
Testicular Hyaluronidase

Fibronectin has been localized to basement membranes and cell surfaces with the light microscope by fluorescent staining of thick sections, and with the TEM by immunoperoxidase reaction. However, these methods are limited because it is difficult to appreciate the patterned distribution of fibronectin from sectioned material. We have developed a probe for fibronectin that facilitates its identification with the SEM. Our probe consists of two parts; the first component is a derivatized methacrylate microsphere 90 nm in diameter, linked to purified sheep anti-rabbit IgG. The second component is anti-fibronectin IgG raised in rabbits. Stage-3 to -12 chick embryos were fixed and the ectoderm covering the cranial mesoderm was removed. Embryos were treated with testicular hyaluronidase, exposed to rabbit antifibronectin IgG and finally to sheep anti-rabbit IgG conjugated microspheres. As expected, the basal lamina of surface and neural ectoderm as well as the remaining fibrous ECM were heavily decorated with microspheres, whereas control embryos treated with preimmune serum were beadless. Fibronectin was localized on the cell soma and processes of primary mesenchyme as early as stage 3. In addition, it was possible to decorate to various extents, populations of prosencephalic, mesencephalic, and rhombencephalic cranial neural crest cells. Our studies suggest that fibronectin is present in the cranium of chick embryos at earlier times than heretofore realized, and that fibronectin accumulates in a cranial to caudal gradient that reflects the sequential differentiation of the embryonic axis.

CX43 expression, phosphorylation, and distribution in the normal and autoimmune orchitic testis with a look at gap junctions joining germ cell to germ cell

2011 ◽  
Vol 300 (1) ◽  
pp. R121-R139 ◽  
Author(s):  
R.-Marc Pelletier ◽  
Casimir D. Akpovi ◽  
Li Chen ◽  
Robert Day ◽  
María L. Vitale
Keyword(s):  
Cell Differentiation ◽  
Gap Junctions ◽  
Germ Cell ◽  
Sertoli Cell ◽  
Sertoli Cells ◽  
Seminiferous Tubule ◽  
Connexin 43 ◽  
Cx43 Expression ◽  
Cx43 Protein ◽  
Cx43 Mrna

Spermatogenesis requires connexin 43 (Cx43).This study examines normal gene transcription, translation, and phosphorylation of Cx43 to define its role on germ cell growth and Sertoli cell's differentiation, and identifies abnormalities arising from spontaneous autoimmune orchitis (AIO) in mink, a seasonal breeder and a natural model for autoimmunity. Northern blot analysis detected 2.8- and a 3.7-kb Cx43 mRNA bands in seminiferous tubule-enriched fractions. Cx43 mRNA increased in seminiferous tubule-enriched fractions throughout development and then seasonally with the completion of spermatogenesis. Cx43 protein levels increased transiently during the colonization of the tubules by the early-stage spermatocytes. Cx43 phosphorylated (PCx43) and nonphosphorylated (NPCx43) in Ser368 decreased during the periods of completion of meiosis and Sertoli cell differentiation, while Cx43 mRNA remained elevated throughout. PCx43 labeled chiefly the plasma membrane except by stage VII when vesicles were also labeled in Sertoli cells. Vesicles and lysosomes in Sertoli cells and the Golgi apparatus in the round spermatids were NPCx43 positive. A decrease in Cx43 gene expression was matched by a Cx43 protein increase in the early, not the late, phase of AIO. Total Cx43 and PCx43 decreased with the advance of orchitis. The study makes a novel finding of gap junctions connecting germ cells. The data indicate that Cx43 protein expression and phosphorylation in Ser368 are stage-specific events that may locally influence the acquisition of meiotic competence and the Sertoli cell differentiation in normal testis. AIO modifies Cx43 levels, suggesting changes in Cx43-mediated intercommunication and spermatogenic activity in response to cytokines imbalances in Sertoli cells.

Sialoconjugates and development of the tail bud

Development ◽  
1990 ◽  
Vol 108 (3) ◽  
pp. 479-489
Author(s):  
C.M. Griffith ◽  
M.J. Wiley
Keyword(s):  
Sialic Acid ◽  
Lectin Histochemistry ◽  
Limulus Polyphemus ◽  
Chick Embryos ◽  
Developmental Sequence ◽  
Tail Bud ◽  
Bud Development ◽  
Stage Of Development ◽  
Higher Doses ◽  
Axial Development

Using lectin histochemistry, we have previously shown that there are alterations in the distribution of glycoconjugates in the tail bud of chick embryos that parallel the developmental sequence of the caudal axis. If glycoconjugates or the cells bearing them play a role in caudal axial development, then, restriction of their availability by binding with lectins would be expected to produce abnormalities of caudal development. In the present study, we treated embryos at various stages of tail bud development by microinjection with a variety of lectins. Administration of WGA by sub-blastodermal injection resulted in high incidences of secondary neural tube and notochordal abnormalities in lectin-treated embryos. The incidence of malformations was dependent upon both the dose of WGA received and the stage of development at the time of treatment. Using an anti-WGA antibody, we have also shown binding of the lectin in regions where defects were found. The lectin WGA binds to the sialic acid residues of glycoconjugates and to N-acetylglucosamine. Treatment of embryos with Limulus polyphemus lectin (LPL), which also binds to sialic acid, produced results similar to those of WGA. Treatments using lectins with other sugar-binding specificities, including succinylated WGA (with N-acetylglucosamine specificity only) produced defects that differed from those produced by WGA and LPL, and only with the administration of much higher doses. The results suggest that glycoconjugates in general and sialoconjugates in particular, or the cells carrying them, may have a role in caudal axial development.

Interleukin-5 (IL-5) and IL-6 define two molecularly distinct pathways of B-cell differentiation

1993 ◽  
Vol 13 (7) ◽  
pp. 3929-3936
Author(s):  
T D Randall ◽  
F E Lund ◽  
J W Brewer ◽  
C Aldridge ◽  
R Wall ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
B Cell Lymphoma ◽  
Receptor Expression ◽  
High Rate ◽  
B Cell Differentiation ◽  
Interleukin 5 ◽  
Stage Of Development ◽  
Differentiation Factors

Interleukin-5 (IL-5) and IL-6 have both been reported to act as B-cell differentiation factors by stimulating activated B cells to secrete antibody. However, it has not been possible to directly compare the effects of these two lymphokines because of the lack of a suitable B-cell line capable of responding to both. We have identified a clonal, inducible B-cell lymphoma, CH12, that has this property. Both IL-5 and IL-6 can independently stimulate increases in steady-state levels of immunoglobulin and J-chain mRNA and proteins, and they both induce the differentiation of CH12 into high-rate antibody-secreting cells. Nevertheless, there are significant differences in the activities of these two lymphokines. First, while IL-6 acts only as a differentiation factor, IL-5 also augments the proliferation of CH12 cells. Second, the differentiation stimulated by IL-5 but not by IL-6 is partially inhibited by IL-4. Inhibition of IL-5-induced differentiation was not at the level of IL-5 receptor expression, since IL-4 did not inhibit IL-5-induced proliferation. Third, IL-5 but not IL-6 stimulated increased mouse mammary tumor proviral gene expression in CH12 cells. These results demonstrate that while both IL-5 and IL-6 may act as differentiation factors for B cells, they induce differentiation by using at least partially distinct molecular pathways. Our results also establish that B cells characteristic of a single stage of development can independently respond to IL-4, IL-5, and IL-6.

Evidence for microtubule nucleation at plasma membrane-associated sites in Drosophila

1987 ◽  
Vol 88 (1) ◽  
pp. 95-107 ◽  
Author(s):  
M.M. Mogensen ◽  
J.B. Tucker
Keyword(s):  
Plasma Membrane ◽  
Cell Differentiation ◽  
Cross Section ◽  
Plasma Membranes ◽  
Early Stage ◽  
Apical Cell ◽  
Apical Plasma Membrane ◽  
Cell Surfaces ◽  
Microtubule Organizing Centres ◽  
Oriented Parallel

This report is concerned with the nucleation and organization of microtubule bundles that assemble after ‘conventional’ centrosomal microtubule-organizing centres have been lost. The microtubule bundles in question span the lengths of wing epidermal cells. Bundles extend between hemidesmosomes at the apical cuticle-secreting surfaces of cells and basal attachment desmosomes that unite the dorsal and ventral epidermal layers of developing wing blades. Furthermore, each bundle includes up to 1500 microtubules and most of the microtubules are composed of 15 protofilaments. Individual cells were serially cross-sectioned at an early stage of bundle assembly. The number of microtubule profiles/cell cross-section decreased progressively by up to 59% of the most apical values in section sequences cut from fairly apical to more basal levels in the cells. The apical ends of microtubules were associated with numerous small dense plaque-like sites (diameter 0.1-0.2 micron), which were specialized regions of plasma membranes at the apical surfaces of cells. Many of the microtubules near apical plaques were not well aligned with each other; they ‘radiated away’ from cell apices. This was in contrast to the situation at more basal levels where most microtubules were oriented parallel to the longitudinal axes of cells. These findings indicate that the relatively dispersed arrays of apical plasma membrane-associated plaques act as microtubule-nucleating sites to initiate basally directed elongation of bundle microtubules. Apical cell surfaces and their plaques seem to operate as microtubule-nucleating and -organizing regions that functionally replace the centrosomal microtubule-organizing centres lost earlier in cell differentiation.

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