Gap-junctional permeability in early and cleavage-arrested ascidian embryos

Development ◽  
1991 ◽  
Vol 112 (1) ◽  
pp. 153-160 ◽  
Author(s):  
B. Dale ◽  
L. Santella ◽  
E. Tosti
Keyword(s):  
Gap Junctions ◽  
Lucifer Yellow ◽  
Cell Voltage ◽  
Spatial Location ◽  
Cell Stage ◽  
Junctional Conductance ◽  
Junctional Permeability ◽  
Cell Embryo ◽  
Ascidian Embryos ◽  
Two Stages

Using the whole-cell voltage clamp technique, we have studied junctional conductance (Gj), and Lucifer Yellow (LY) coupling in 2-cell and 32-cell ascidian embryos. Gj ranges from 17.5 to 35.3 nS in the 2-cell embryo where there is no passage of LY, and from 3.5 to 12.2 nS in the later embryo where LY dye spread is extensive. In both cases, Gj is independent of the transjunctional potential (Vj). Manually apposed 2-cell or 32-cell embryos established a junctional conductance of up to 10 nS within 30 min of contact. Furthermore, since we did not observe any significant number of cytoplasmic bridges at the EM and Gj is sensitive to octanol, it is probable that blastomeres in the 2-cell and 32-cell embryos are in communication by gap junctions. In order to compare Gj in the two stages and to circumvent problems of cell size, movement and spatial location, we used cytochalasin B to arrest cleavage. Gj in cleavage-arrested 2-cell embryos ranged from 25.0 to 38.0 nS and remained constant over a period of 2.5 h. LY injected into a blastomere of these arrested embryos did not spread to the neighbour cell until they attained the developmental age of a 32- to 64-cell control embryo. Our experiments indicate a change in selectivity of gap junctions at the 32-cell stage that is not reflected by a macroscopic change in ionic permeability.

Patterns of junctional communication during development of the early amphibian embryo

Development ◽  
1988 ◽  
Vol 103 (4) ◽  
pp. 769-783 ◽  
Author(s):  
S. Guthrie ◽  
L. Turin ◽  
A. Warner
Keyword(s):  
Gap Junctions ◽  
Lucifer Yellow ◽  
Dorsal Side ◽  
Cell Stage ◽  
Animal Pole ◽  
Amphibian Embryo ◽  
Grey Crescent ◽  
The Future ◽  
Junctional Permeability ◽  
Side Gap

Cell-cell communication through gap junctions was examined in Xenopus laevis embryos between the 16-cell and early blastula stages using Lucifer Yellow, Fluorescein, lead EDTA and dicyanoargentate as probes of junctional permeability. Injections were made into cells whose position was identified with respect to the primary cleavage axis and the grey crescent. FITC dextrans revealed cytoplasmic bridges between the injected cell and its sister only. In the animal pole at the 16-cell stage at the future dorsal side of the embryo, Lucifer Yellow was frequently and extensively transferred between cells through gap junctions. At the future ventral side gap junctional transfer of Lucifer Yellow was significantly less frequent and less extensive. The asymmetry of transfer between future dorsal and ventral sides of the animal pole was more marked at the 32-cell stage. In the vegetal pole also at the 32-cell stage, a dorsoventral difference in junctional permeability to Lucifer Yellow was observed. At the 64-cell stage the transfer of Lucifer Yellow was relatively frequent between cells lying in the same radial segment in the animal pole; transfer into cells outside each segment was infrequent, except at the grey crescent. At the 128-cell stage, Lucifer transfer between future dorsal or future ventral cells in the equatorial region was infrequent. A high incidence of transfer was restored at the future dorsal side at the 256-cell stage. At the 32-cell stage, fluorescein was infrequently transferred between animal pole cells although lead EDTA moved from cell to cell with high, comparable frequency in future dorsal and ventral regions. Dicyanoargentate always transferred extensively, both at the 32- and 64-cell stages. Treatment of embryos with methylamine raised intracellular pH by 0.15 units, increased the electrical conductance of the gap junction and produced a 10-fold increase in the frequency of Lucifer Yellow transfer through gap junctions in future ventral regions of the animal pole at the 32-cell stage.

Intercellular communication in the early embryo of the ascidian Ciona intestinalis

Development ◽  
1988 ◽  
Vol 102 (1) ◽  
pp. 55-63 ◽  
Author(s):  
F. Serras ◽  
C. Baud ◽  
M. Moreau ◽  
P. Guerrier ◽  
J.A.M. Van den Biggelaar
Keyword(s):  
Intercellular Communication ◽  
Lucifer Yellow ◽  
Ciona Intestinalis ◽  
Early Embryo ◽  
Cell Stage ◽  
Early Embryos ◽  
Junctional Conductance ◽  
Voltage Dependent ◽  
Cytoplasmic Bridges ◽  
Series Of Experiments

We have studied the intercellular communication pathways in early embryos of the ascidian Ciona intestinalis. In two different series of experiments, we injected iontophoretically the dyes Lucifer Yellow and Fluorescein Complexon, and we analysed the spread of fluorescence to the neighbouring cells. We found that before the 32-cell stage no dye spread occurs between nonsister cells, whereas sister cells are dye-coupled, possibly via cytoplasmic bridges. After the 32-cell stage, dye spread occurs throughout the embryo. However, electrophysiological experiments showed that nonsister cells are ionically coupled before the 32-cell stage. We also found that at the 4-cell stage junctional conductance between nonsister cells is voltage dependent, which suggests that conductance is mediated by gap junctions in a way similar to that observed in other embryos.

The correlation between patterns of dye transfer junctions and future developmental fate in Xenopus: u.v. irradiation and lithium treatment

Development ◽  
1989 ◽  
Vol 105 (4) ◽  
pp. 747-752 ◽  
Author(s):  
D.J. Nagajski ◽  
S.C. Guthrie ◽  
C.C. Ford ◽  
A.E. Warner
Keyword(s):  
Lucifer Yellow ◽  
Lithium Treatment ◽  
Cell Communication ◽  
Embryonic Axis ◽  
Axis Formation ◽  
Dye Transfer ◽  
Cell Stage ◽  
The Future ◽  
Vegetal Pole ◽  
Cell Embryo

The correlation between cell-to-cell communication junctions at the 32-cell stage and the subsequent embryonic axis has been examined in Xenopus laevis Disturbances of embryonic axis formation were u.v. irradiation at the vegetal pole before 0.6 in the which generates embryos with dorsal axial embryos were treated with 100mM-lithium chloride 32-cell stage, which generates embryos with ventral The cell-to-cell transfer of Lucifer Yellow was used junctional permeability. Injections were made into cells, lying in tiers 1 and 2 of the 32-cell embryo, relative to the future dorsoventral axis of the embryo on the basis of differences in pigmentation. The Yellow transfer in the future dorsal half of the compared with that in the future ventral half for u.v.-irradiated and Li-treated embryos. Injected subsequently scored for axial developmenf for transfer frequencies. In control embryos at the 32- Yellow transfer was both more frequent and more dorsal regions than in future ventral regions, as In embryos that had been u.v. irradiated before 0.6 in cycle, Lucifer transfer was the same in both light and the animal hemisphere and at the low level ventral regions in normal embryos. These embryos reductions in dorsal axial structures. Embryos the first cell cycle, when u.v. irradiation no longer cytoplasmic movements initiated at fertilization, dorsoventral difference in Lucifer Yellow transfer and normal dorsoventral polarity. Embryos exposed to

Reduced gap junctional communication is associated with the lethal condition characteristic of DDK mouse eggs fertilized by foreign sperm

Development ◽  
1987 ◽  
Vol 101 (3) ◽  
pp. 449-459 ◽  
Author(s):  
M. Buehr ◽  
S. Lee ◽  
A. McLaren ◽  
A. Warner
Keyword(s):  
Gap Junctions ◽  
Lucifer Yellow ◽  
Blastocyst Stage ◽  
Weak Base ◽  
Cell Stage ◽  
Gap Junctional Communication ◽  
Junctional Communication ◽  
Condition Characteristic ◽  
Gap Junctional ◽  
Mouse Eggs

Communication through gap junctions was examined in 8-cell zygotes generated by fertilization of eggs of the DDK inbred strain of mice with spermatozoa of the C3H strain. These zygotes spontaneously begin to extrude cells at the late 16-cell stage and 95% die by the blastocyst stage. The transfer of Lucifer Yellow between cells of DDK/C3H zygotes that had not yet begun to express the defect was significantly slower than in DDK/DDK controls or in controls from other strains. Treatment with the weak base methylamine, to raise intracellular pH, speeded the transfer of Lucifer in all strains; transfer between cells of DDK/C3H zygotes became as fast as that between cells of control zygotes. DDK/C3H zygotes cultured in methylamine either from the 4- to 8-cell stage to the early 16-cell stage (19h) or from the early to the late 16-cell stage (6 h) showed significant rescue to the blastocyst stage. Once spontaneous decompaction of cells from DDK/C3H zygotes had begun (the late 16-cell stage onwards) methylamine treatment was no longer able to bring about rescue. We conclude that zygotes developed from eggs of the DDK strain fertilized by foreign spermatozoa are characterized physiologically by defective gap junctional communication. Improving gap junctional communication is sufficient to allow many zygotes to maintain the compacted state, suggesting a link between compaction and communication through gap junctions.

scholarly journals Connexin26 deafness associated mutations show altered permeability to large cationic molecules

2008 ◽  
Vol 295 (4) ◽  
pp. C966-C974 ◽  
Author(s):  
Gülistan Meşe ◽  
Virginijus Valiunas ◽  
Peter R. Brink ◽  
Thomas W. White
Keyword(s):  
Gap Junctions ◽  
Voltage Clamp ◽  
Intercellular Communication ◽  
Essential Role ◽  
Lucifer Yellow ◽  
Cell Voltage ◽  
Wild Type ◽  
Transfected Cells ◽  
Large Molecules ◽  
Ionic Coupling

Intercellular communication is important for cochlear homeostasis because connexin26 (Cx26) mutations are the leading cause of hereditary deafness. Gap junctions formed by different connexins have unique selectivity to large molecules, so compensating for the loss of one isoform can be challenging in the case of disease causing mutations. We compared the properties of Cx26 mutants T8M and N206S with wild-type channels in transfected cells using dual whole cell voltage clamp and dye flux experiments. Wild-type and mutant channels demonstrated comparable ionic coupling, and their average unitary conductance was ∼106 and ∼60 pS in 120 mM K+-aspartate− and TEA+-aspartate− solution, respectively, documenting their equivalent permeability to K+ and TEA+. Comparison of cAMP, Lucifer Yellow (LY), and ethidium bromide (EtBr) transfer revealed differences in selectivity for larger anionic and cationic tracers. cAMP and LY permeability to wild-type and mutant channels was similar, whereas the transfer of EtBr through mutant channels was greatly reduced compared with wild-type junctions. Altered permeability of Cx26 to large cationic molecules suggests an essential role for biochemical coupling in cochlear homeostasis.

Gap-junctional properties of electrically coupled skate horizontal cells in culture

1993 ◽  
Vol 10 (2) ◽  
pp. 287-295 ◽  
Author(s):  
Haohua Qian ◽  
Robert Paul Malchow ◽  
Harris Ripps
Keyword(s):  
Receptive Field ◽  
Lucifer Yellow ◽  
Horizontal Cell ◽  
Electrical Coupling ◽  
Cell Voltage ◽  
Horizontal Cells ◽  
Electrical Synapse ◽  
Cell Coupling ◽  
Junctional Conductance ◽  
Gap Junctional

AbstractWhole-cell voltage-clamp recordings were used to examine the unusual pharmacological properties of the electrical coupling between rod-driven horizontal cells in skate retina as revealed previously by receptive-field measurements (Qian & Ripps, 1992). The junctional resistance was measured in electrically coupled cell pairs that had been enzymatically isolated and maintained in culture; the typical value was about 19.92 MΩ(n = 45), more than an order of magnitude lower than the nonjunctional membrane resistance. These data and the intercellular spread of the fluorescent dye Lucifer Yellow provide a good indication that skate horizontal cells are well coupled. The junctional conductance between cells was not modulated by the neurotransmitters dopamine (200 μM) or GABA (1 mM), nor was it affected by the membrane-permeable analogues of cAMP or cGMP, or the adenylate cyclase activator, forskolin. Although resistant to agents that have been reported to alter horizontal-cell coupling in cone-driven horizontal cells, the junctional conductance between paired horizontal cells of skate was greatly reduced by the application of 20 mM acetate, which is known to effectively reduce intracellular pH. Together with the results obtained in situ on the receptive-field properties of skate horizontal cells, these findings indicate that the gap-junctional properties of rod-driven horizontal cells of the skate are fundamentally different from those of cone-driven horizontal cells in other species. This raises the possibility that there is more than one class of electrical synapse on vertebrate horizontal cells.

Muscle cell differentiation in ascidian embryos analysed with a tissue-specific monoclonal antibody

Development ◽  
1987 ◽  
Vol 99 (2) ◽  
pp. 163-171
Author(s):  
T. Nishikata ◽  
I. Mita-Miyazawa ◽  
T. Deno ◽  
N. Satoh
Keyword(s):  
Monoclonal Antibody ◽  
Cell Differentiation ◽  
Muscle Cell ◽  
Antigen Expression ◽  
Relative Molecular Mass ◽  
Specific Monoclonal Antibody ◽  
Cell Stage ◽  
Muscle Cell Differentiation ◽  
Cell Embryo ◽  
Ascidian Embryos

Utilizing a muscle-specific monoclonal antibody (Mu-2) as a probe, we analysed developmental mechanisms involved in muscle cell differentiation in ascidian embryos. The antigen recognized by Mu-2 was a single polypeptide with a relative molecular mass of about 220 X 10(3). It first appeared at the early tailbud stage and continued to be expressed until the swimming larva stage. There were distinct and separate puromycin and actinomycin D sensitivity periods during the occurrence of the antigen, suggesting the new synthesis of the polypeptide by developing muscle cells. Embryos that had been permanently arrested with aphidicolin in the early cleavage stages up to the 32-cell stage did not express the antigen. DNA replications may be required for the antigen expression. Embryos that had been arrested with cytochalasin B in the 8-cell and later stages developed the antigen, and the number and position of the arrested blastomeres exhibiting the differentiation marker almost corresponded to those of the B4.1-line muscle lineage. Furthermore, in quarter embryos developed from each blastomere pair isolated from the 8-cell embryo, all the B4.1 as well as a part of b4.2 partial embryos expressed the antigen, while the a4.2 and A4.1 partial embryos did not show the antigen expression. These results may provide further support for the existence of cytoplasmic determinants for muscle cell differentiation in this mosaic egg.

Acetylcholinesterase development in extra cells caused by changing the distribution of myoplasm in ascidian embryos

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 343-354
Author(s):  
J. R. Whittaker
Keyword(s):  
Cytochalasin B ◽  
Continuous Treatment ◽  
Functional Specificity ◽  
Cell Stage ◽  
Division Plane ◽  
Styela Plicata ◽  
Developmental Fate ◽  
Ascidian Embryos ◽  
Functional Autonomy ◽  
Ascidian Embryo

This research shows that myoplasmic crescent material of the ascidian egg has both functional autonomy and functional specificity in establishing the differentiation pathway of muscle lineage cells. The cytoplasmic segregation pattern in eggs of Styela plicata was altered by compression of the embryos during third cleavage. This caused a meridional division instead of the normal equatorial third cleavage; first and second cleavages are meridional. Since eggs of S. plicata have a pronounced yellow myoplasmic crescent, one observes directly that third cleavage under compression resulted in a flat 8-cell stage with four cells containing yellow myoplasm instead of the two myoplasm-containing cells that would be formed by normal equatorial division at third cleavage. If such altered 8-cell-stage embryos were released from compression and kept from undergoing further divisions by continuous treatment with cytochalasin B, some embryos eventually developed histospecific acetylcholinesterase in three and four cells instead of in just the two muscle lineage cells found in cleavage-arrested normal 8-cell stages. The wider myoplasmic distribution effected by altering the division plane at third cleavage apparently caused a change in developmental fate of the extra cells receiving myoplasm. This meridional third cleavage also resulted in a changed nuclear lineage pattern. Two nuclei that would ordinarily be in ectodermal lineage cells after third cleavage were now associated with yellow myoplasm. Acetylcholinesterase development in these cells demonstrates that nuclear lineages are not responsible for muscle acetylcholinesterase development in the ascidian embryo.

Distribution of microvilli on dissociated blastomeres from mouse embryos: evidence for surface polarization at compaction

Development ◽  
1981 ◽  
Vol 62 (1) ◽  
pp. 339-350
Author(s):  
W. J. D. Reeve ◽  
C. A. Ziomek
Keyword(s):  
Ligand Binding ◽  
Single Cells ◽  
Progressive Increase ◽  
Mouse Embryos ◽  
Cell Stage ◽  
Characteristic Distribution ◽  
Surface Polarization ◽  
Cell Embryo ◽  
Fluorescent Ligand ◽  
Scanning Electron

Cells of mouse embryos develop a polarization of microvillous distribution at compaction. Cells of the 4-cell embryo show a uniform pattern of fluorescent-ligand binding and an even distribution of microvilli. Each cell of the early 8-cell embryo has a uniform distribution both of microvilli and of fluorescent ligand. During the 8-cell stage, there is a progressive increase in the incidence of cells which show microvilli restricted to a region normally on the exposed surface of the embryo. When late 8-cell embryos were disaggregated to single cells, and these sorted by pattern of fluorescent-ligand binding, each of the four patterns of staining related consistently to a characteristic distribution of microvilli as viewed by scanning electron microscopy. The 16-cell embryo possessed an inside population of uniformly labelled cells with a sparse microvillous distribution, and an outside population of cells, each of which had a microvillous pole.

Gap junction expression and cell proliferation in differentiating cultures of Cx43 KO mouse hepatocytes

2001 ◽  
Vol 281 (4) ◽  
pp. G1004-G1013 ◽  
Author(s):  
Takashi Kojima ◽  
Alfredo Fort ◽  
Mingyuan Tao ◽  
Masao Yamamoto ◽  
David C. Spray
Keyword(s):  
Lucifer Yellow ◽  
Primary Cultures ◽  
Mrna Levels ◽  
Wild Type ◽  
Dye Transfer ◽  
Gap Junctional Communication ◽  
Junctional Communication ◽  
Junctional Conductance ◽  
Mouse Hepatocytes

Primary cultures of adult mouse hepatocytes are shown here to reexpress differentiated hepatocyte features following treatment with 2% DMSO and 10−7 M glucagon. To examine the roles of gap junctional communication during hepatocyte growth and differentiation, we have compared treated and untreated hepatocytes from connexin (Cx)32-deficient [Cx32 knockout (KO)] and wild-type mice. In untreated cultures, DNA replication of Cx32 KO hepatocytes was markedly higher than of wild types. Although Cx26 mRNA levels remained high at all time points in wild-type and Cx32 KO hepatocytes, Cx32 mRNA and protein in wild-type hepatocytes underwent a marked decline, which recovered in 10-day treated cultures. Increased levels of Cx26 protein and junctional conductance were observed in Cx32 KO hepatocytes at 96 h in culture, a time when cell growth rate was high. Treatment with DMSO/glucagon highly reinduced Cx26 expression in Cx32 KO hepatocytes, and such treatment reinduced expression of both Cx32 and Cx26 expression in wild types. Dye transfer was not observed following Lucifer yellow injection into DMSO/glucagon-treated Cx32 KO hepatocytes, whereas the spread was extensive in wild types. Nevertheless, high junctional conductance values were observed in treated cells from both genotypes. These studies provide a method by which the differentiated phenotype can be obtained in cultured mouse hepatocytes and provide in vitro evidence that expression of gap junctions formed of Cx32 are involved in the regulation of growth of mouse hepatocytes.

Sign in / Sign up

Export Citation Format

Share Document