scholarly journals THE DEVELOPMENT OF SURFACE SPECIALIZATION IN THE SECRETORY EPITHELIUM OF THE AVIAN SALT GLAND IN RESPONSE TO OSMOTIC STRESS

1969 ◽  
Vol 40 (2) ◽  
pp. 305-321 ◽  
Author(s):  
Stephen A. Ernst ◽  
Richard A. Ellis
Keyword(s):  
Osmotic Stress ◽  
Salt Gland ◽  
Secretory Cells ◽  
Cell Surfaces ◽  
Secretory Epithelium ◽  
Transitional Cells ◽  
Peripheral Cells ◽  
Lateral Cell ◽  
Generative Cells ◽  
Surface Specialization

Cell surface specialization, a characteristic common to most ion-transporting epithelia, was studied in the salt (nasal) gland of the domestic duck in relation to osmotic stress. Three days after hatching, experimental ducklings were given 1% NaCl to drink for 12 hr and freshwater for the remainder of each day. Control ducklings were maintained exclusively on freshwater. The fine structure of the secretory epithelium was examined on various days of the regimen. The nasal gland epithelium of the secretory lobule is composed of several types of cells. Peripheral cells, lying at the blind ends of the branched secretory tubules, are similar in both control and experimental animals at all stages of glandular development. These generative cells contain few mitochondria and have nearly smooth cell surfaces. Partially specialized secretory cells predominate in the secretory tubules of control animals and appear as transitional cells in the tubular epithelium of salt-stressed animals. These cells contain few mitochondria and bear short folds along their lateral cell surfaces. Fully specialized cells dominate the secretory epithelium of osmotically stressed ducklings. The lateral and basal surfaces of these cells are deeply folded, forming complex intra- and extracellular compartments. This vast increase in absorptive surface area is paralleled by an increase in the number of mitochondria that pack the basal compartments. The development of this fully specialized cell is correlated with the marked increase in (Na+-K+)-ATPase activity in the glands of osmotically stressed birds.

In vivo and in vitro induction of c-fos in avian exocrine salt gland cells

1998 ◽  
Vol 275 (4) ◽  
pp. C951-C957 ◽  
Author(s):  
Jan-Peter Hildebrandt ◽  
Rüdiger Gerstberger ◽  
Marion Schwarz
Keyword(s):  
Osmotic Stress ◽  
Salt Gland ◽  
Receptor Activation ◽  
Secretory Cells ◽  
Muscarinic Agonists ◽  
Gland Tissue ◽  
Muscarinic Ach Receptor ◽  
Nasal Glands

Osmotic stress in ducklings ( Anas platyrhynchos) results in salt secretion and adaptive cell proliferation and differentiation in the nasal glands. We investigated whether osmotic stress in vivo or muscarinic ACh receptor activation in vitro changed the expression levels of the cellular protooncogene products Fos and Jun, which may play a role in the initiation of the adaptive processes. Using Fos- and Jun-specific polyclonal antisera in Western blot experiments, we demonstrated that Jun is constitutively expressed in nasal gland tissue, whereas Fos is not detectable in tissue from unstressed (naive) animals. Under conditions of osmotic stress imposed by replacing the drinking water of the animals with a 1% NaCl solution, Jun protein remains constant in nasal gland tissue, whereas Fos protein is transiently upregulated. Treatment of cultured nasal gland tissue with muscarinic agonists results in a transcriptionally regulated expression of Fos in an atropine-sensitive manner. Immunohistochemical experiments show that Fos accumulation occurs in the nuclei of the secretory cells. These results indicate that the activation of the c- fos gene induced by muscarinic ACh receptor-mediated signaling pathways may play an important role in the initiation of adaptive growth and differentiation processes in nasal glands of osmotically stressed ducklings.

scholarly journals Basolateral plasma membrane localization of ouabain-sensitive sodium transport sites in the secretory epithelium of the avian salt gland

1977 ◽  
Vol 75 (1) ◽  
pp. 74-94 ◽  
Author(s):  
SA Ernst ◽  
JW Mills
Keyword(s):  
Plasma Membrane ◽  
Binding Sites ◽  
Salt Gland ◽  
Physiological Data ◽  
Secretory Cells ◽  
Ouabain Binding ◽  
Salt Glands ◽  
Cytochemical Localization ◽  
Secretory Epithelium ◽  
Basolateral Plasma Membrane

The distribution of Na+ pump sites (Na+-K+-ATPase) in the secretory epithelium of the avian salt gland was demonstrated by freeze-dry autoradiographic analysis of [(3)H] ouabain binding sites. Kinetic studies indicated that near saturation of tissue binding sites occurred when slices of salt glands from salt-stressed ducks were exposed to 2.2 μM ouabain (containing 5 μCi/ml [(3)H]ouabain) for 90 min. Washing with label-free Ringer's solution for 90 min extracted only 10% of the inhibitor, an amount which corresponded to ouabain present in the tissue spaces labeled by [(14)C]insulin. Increasing the KCl concentration of the incubation medium reduced the rate of ouabain binding but not the maximal amount bound. In contrast to the low level of ouabain binding to salt glands of ducks maintained on a freshwater regimen, exposure to a salt water diet led to a more than threefold increase in binding within 9-11 days. This increase paralleled the similar increment in Na+-K+-ATPase activity described previously. [(3)H]ouabain binding sites were localized autoradiographically to the folded basolateral plasma membrane of the principal secretory cells. The luminal surfaces of these cells were unlabeled. Mitotically active peripheral cells were also unlabeled. The cell-specific pattern of [(3)H]ouabain binding to principal secretory cells and the membrane-specific localization of binding sites to the nonluminal surfaces of these cells were identical to the distribution of Na+-K+-ATPase as reflected by the cytochemical localization of ouabain-sensitive and K+-dependent nitrophenyl phosphatase activity. The relationship between the nonluminal localization of Na+-K+-ATPase and the possible role of the enzyme n NaCl secretion is considered in the light of physiological data on electrolyte transport in salt glands and other secretory epithelia.

Biogenesis of Plasma Membranes in Salt Glands of Salt-Stressed Domestic Ducklings: Localization of Acyltransferase Activity

1972 ◽  
Vol 11 (3) ◽  
pp. 855-873
Author(s):  
A. M. LEVINE ◽  
JOAN A. HIGGINS ◽  
R. J. BARRNETT
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Salt Gland ◽  
Secretory Cells ◽  
Salt Glands ◽  
Acyltransferase Activity ◽  
Structural Localization ◽  
Differentiated Cells ◽  
Golgi Membranes

In response to salt water stress there is a marked increase in the plasma membranes of the epithelial secretory cells of the salt glands of domestic ducklings. In the present study, the fine-structural localization of the acyltransferases involved in synthesis of phospholipids has been investigated in this tissue during this increased biogenesis of plasma membranes. The specific activity of the acyltransferases of the salt gland rose in response to salt stress, and this preceded the rapid increase in weight and cellular differentiation. After the weight increase of the gland became established, the specific activity of the acyltransferases declined, but the total activity remained constant. Salt gland tissue fixed in a mixture of glutaraldehyde and formaldehyde retained 35% of the acyltransferase activity of unfixed tissue. Cytochemical studies of the localization of acyltransferase activity in fixed and unfixed salt gland showed reaction product associated only with the lamellar membranes of the Golgi complex. This localization occurred in partially differentiated cells from salt-stressed glands to the greatest extent; and to only a small extent in cells of control tissue from unstressed salt glands. Omission of substrates resulted in absence of reaction product in association with the Golgi membranes. In addition, vesicles having limiting membranes morphologically similar to the plasma membrane occurred between the Golgi region and the plasma membrane in the partially differentiated cells. The phospholipid component of the plasma membrane appears therefore to be synthesized in association with the Golgi membranes and the membrane packaged at this site from which it moves in the form of vesicles to fuse with the pre-existing plasma membrane.

The involvement of adherens junction components in myofibrillogenesis in cultured cardiac myocytes

Development ◽  
1992 ◽  
Vol 114 (1) ◽  
pp. 173-183 ◽  
Author(s):  
E.J. Goncharova ◽  
Z. Kam ◽  
B. Geiger
Keyword(s):  
Alternative Pathway ◽  
Three Dimensional ◽  
Adherens Junction ◽  
Intercellular Junctions ◽  
Inhibitory Effect ◽  
Newborn Rats ◽  
Cell Surfaces ◽  
Cell Matrix ◽  
Adhesive Interactions ◽  
Lateral Cell

The distribution of adherens junction (AJ) components was investigated in cultured heart myocytes. These cells, derived from either newborn rats or chick embryos, develop elaborate arrays of myofibrils which become extensive and laterally aligned following several days in culture. The Z-disks in these cells, visualized by immunolabeling with antibodies to muscle-specific alpha-actinin, exhibit a characteristic periodicity of about 2 microns and are in register with those of neighboring myofibrils throughout the sarcoplasm. Vinculin, in these cells, associates with intercellular AJ and cell-matrix adhesions. In addition, this protein is detected in periodic bands located along the lateral cell membranes corresponding to “costamers” previously described by Pardo, J.V., Siliciano, J.D. and Craig, S.W. (Proc. Natn. Acad. Sci. USA, 80, 1008). Similarly, N-cadherin, which is predominantly associated with intercellular junctions, is also detected in periodic striations located mainly on the dorsal and lateral cell surfaces. Using computer-aided three-dimensional microscopy confirmed that these vinculin- and N-cadherin-containing structures are located in extrajunctional sites, apparently associated with Z-disks of peripheral myofibrils. Based on these findings an alternative pathway is proposed for the assembly of vinculin and N-cadherin, which is not triggered by adhesive interactions with extracellular surfaces but rather by interactions at the membrane-cytoplasm interphase with the periphery of the pre-assembled myofibrils. Moreover, we present evidence that antibodies to N-cadherin, which are capable of blocking AJ formation in culture, have an inhibitory effect also on the development and alignment of myofibrils. We discuss the functional significance of the “costameric” organization of vinculin and N-cadherin and consider its involvement both in the lateral alignment of neighboring muscle cells and in the stabilization of developing myofibrils.

Multiple calcium mobilization pathways in single avian salt gland cells

1990 ◽  
Vol 258 (2) ◽  
pp. C289-C298 ◽  
Author(s):  
E. L. Stuenkel ◽  
S. A. Ernst
Keyword(s):  
Salt Gland ◽  
Transient Increase ◽  
Secretory Cells ◽  
Free Medium ◽  
Subsequent Removal ◽  
Intracellular Pool ◽  
Gland Cells ◽  
Agonist Stimulation ◽  
Induced Changes ◽  
Sustained Increase

Agonist-induced changes in intracellular Ca2+ concentration ([Ca2+]i) in individual secretory cells from the avian salt gland were detailed using dual-wavelength microspectrofluorimetry of the Ca2(+)-sensitive fluorescent probe fura-2. Resting [Ca2+]i averaged 42 +/- 5 nM. Stimulation with the cholinergic agonist carbachol (1 microM) resulted in a rapid increase in [Ca2+]i to 308 +/- 26 nM, which was sustained at a nearly constant elevated level (328 +/- 31 nM) throughout agonist application. In the absence of extracellular Ca2+ or in the presence of an inorganic blocker of Ca2+ entry (Ni2+, 1 mM), only a transient increase in [Ca2+]i occurred on agonist stimulation, whereas subsequent readmission of Ca2+ or washout of Ni2+ reinitiated a sustained increase in [Ca2+]i. The initial transient response results from Ca2+ release from intracellular stores, whereas the sustained phase represents entry of extracellular Ca2+ into the cytoplasm. Repetitive stimulations in Ca2(+)-free medium alternating with Ca2(+)-containing medium were performed to examine the mechanisms involved in refilling of the agonist-sensitive intracellular pool. After depletion of the intracellular pool by stimulation in Ca2(+)-free medium, removal of the agonist and readmission of Ca2+ resulted in a rapid transient increase in [Ca2+]i that could be blocked by Ni2+, La3+, or elevated K+. Subsequent removal of extracellular Ca2+ and restimulation nonetheless showed that complete refilling of the intracellular pool had occurred in each case. These results suggest that two separate Ca2(+)-entry mechanisms, one sensitive to Ni2+, La3+, and elevated K+ and responsible for the agonist-induced increase in [Ca2+]i and one insensitive to the blockers and involved in refilling of the intracellular pool, may exist in salt gland cells. Spontaneous oscillations of [Ca2+]i that are independent of extracellular Ca2+ have also been observed in 10% of the cells. The abolition of the oscillations by depletion of the agonist-sensitive pool suggests this pool as the Ca2+ source for the oscillations.

Primary culture of duck salt gland. I. Morphology of confluent cell layers

1985 ◽  
Vol 249 (1) ◽  
pp. C32-C40 ◽  
Author(s):  
R. J. Lowy ◽  
J. H. Schreiber ◽  
D. C. Dawson ◽  
S. A. Ernst
Keyword(s):  
Electron Microscopy ◽  
Primary Culture ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Salt Gland ◽  
Direct Access ◽  
Secretory Cells ◽  
Collagen Gels ◽  
Lateral Membrane ◽  
Confluent Cell

Dissociated avian salt gland secretory cells were maintained in primary culture after plating on hydrated collagen gels. When seeded at 3 X 10(6) cells/cm2, confluent cell sheets formed within 2-3 days, whereas cultures seeded at lower densities formed a complex reticulum of cell aggregates, which remained nonconfluent even after 7 days. Scanning electron microscopy showed that the free surface of 3-day confluent cultures consisted of intermixed convex and flattened cell membranes with prominent junctional boundaries and abundant microvilli. Transmission electron microscopy indicated that these cultures were multilayers of 1-4 cells in thickness. The plasma membranes of the superficial cells were polarized into apical and basolateral regions displaying, respectively, microvilli and interdigitating lateral membrane folds. These membrane domains were separated by shallow occluding junctions, which consisted of both single strands and simple net-like arrays in freeze-fracture images. Underlying epithelial cells retained lateral membrane folds and formed desmosomal contacts with superficial and neighboring cells. These cultures, unlike the intact tissue, allow direct access to the apical and basolateral cell surfaces for electrophysiological analysis of transmural active ion transport.

Key molecules in the GABA signalling pathway are present in mouse and human cervical tissue

2018 ◽  
Vol 30 (9) ◽  
pp. 1267
Author(s):  
Marta Skelin ◽  
Danijel Bursać ◽  
Viviana Kozina ◽  
Tristan Winters ◽  
Marija Macan ◽  
...  
Keyword(s):  
Superficial Layer ◽  
Signalling Pathway ◽  
Mucus Secretion ◽  
Secretory Cells ◽  
Acid Decarboxylase ◽  
Gamma Aminobutyric Acid ◽  
Cervical Tissue ◽  
Secretory Epithelium ◽  
Mrna Transcripts ◽  
Glutamic Acid Decarboxylase 65

Cervical mucus modulates fertility by cyclical changes of its biophysical and functional properties. Based on an analogy with bronchial goblet cells we set out to investigate the possible role of the gamma-aminobutyric acid (GABA) signalling pathway in the mediation of oestrogen-induced mucus secretion from endocervical secretory cells. The aim of the study was to examine the existence of GABAA receptor (GABAAR), glutamic acid decarboxylase 65/67 (GAD65/67) and vesicular GABA transporter (VGAT) in human and mouse cervical tissue. The mouse cervical tissue expressed GabaAR mRNA transcripts throughout the oestrous cycle. GABAAR-positive immunolabelling was present in the superficial layer of the mouse cervico–vaginal epithelium in pro-oestrus. Human cervical tissue showed the presence of GABAAR, GAD67 and VGAT mRNA transcripts and clear immunofluorescent signals of all three molecules were detected in the endocervical secretory epithelium. The results of this study confirmed that elements of the GABA signalling pathway are present in the secretory epithelium of mouse and human cervical tissue and that GABA signalling pathway could be considered a possible mediator in oestrogen regulation of mucus secretion in the endocervical glands.

Evidence for a dual control, by neurosecretion, of hormone synthesis and hormone release in the pituitary of the dogfish scylliorhinus stellaris

1965 ◽  
Vol 249 (760) ◽  
pp. 435-455 ◽  
Keyword(s):  
Direct Contact ◽  
Type A ◽  
Secretory Cells ◽  
Dual Control ◽  
Hormone Release ◽  
Type B ◽  
Intimate Contact ◽  
Hormone Synthesis ◽  
Elasmobranch Fish ◽  
Peripheral Cells

The intrinsic secretory cells of the neuro-intermediate lobes of the pituitary of the elasmobranch fish Scylliorhinus stellaris belong to two main categories (1) central cells which do not demonstrate any marked polarity of their cytoplasmic organelles and show no clear indications of being under neurosecretory control, and (2) peripheral cells which are polarized along an axis from a synthetic pole to a storage and release pole. Neurosecretory fibres make intimate contact with the two poles of these peripheral cells. The neurosecretory fibres may be classed as type A or type B by the size and appearance of the elementary neurosecretory vesicles they contain. These two fibres innervate the synthetic and release poles of the intrinsic cells respectively by direct contact of their terminals to form secretomotor junctions. It seems likely that there is a dual control of synthesis and release of a melanophore-dispersing hormone (MSH). The possibility that type A fibres inhibit synthesis by a peptide substance with oxytocic action, and that MSH release is controlled by amine production by type B fibres is discussed.

scholarly journals Membrane domains of intestinal epithelial cells: distribution of Na+,K+-ATPase and the membrane skeleton in adult rat intestine during fetal development and after epithelial isolation.

1989 ◽  
Vol 109 (5) ◽  
pp. 2129-2138 ◽  
Author(s):  
H M Amerongen ◽  
J A Mack ◽  
J M Wilson ◽  
M R Neutra
Keyword(s):  
Cell Adhesion ◽  
Basolateral Membrane ◽  
Membrane Skeleton ◽  
Membrane Domain ◽  
Cell Surfaces ◽  
Adult Rat ◽  
Lateral Membrane ◽  
Epithelial Sheets ◽  
Lateral Cell ◽  
Fetal Intestine

The organization of the basolateral membrane domain of highly polarized intestinal absorptive cells was studied in adult rat intestinal mucosa, during development of polarity in fetal intestine, and in isolated epithelial sheets. Semi-thin frozen sections of these tissues were stained with a monoclonal antibody (mAb 4C4) directed against Na+,K+-ATPase, and with other reagents to visualize distributions of the membrane skeleton (fodrin), an epithelial cell adhesion molecule (uvomorulin), an apical membrane enzyme (aminopeptidase), and filamentous actin. In intact adult epithelium, Na+,K+-ATPase, membrane-associated fodrin, and uvomorulin were concentrated in the lateral, but not basal, subdomain. In the stratified epithelium of fetal intestine, both fodrin and uvomorulin were localized in areas of cell-cell contact at 16 and 17 d gestation, a stage when Na+,K+-ATPase was not yet expressed. These molecules were excluded from apical domains and from cell surfaces in contact with basal lamina. When Na+,K+-ATPase appeared at 18-19 d, it was codistributed with fodrin. Detachment of epithelial sheets from adult intestinal mucosa did not disrupt intercellular junctions or lateral cell contacts, but cytoplasmic blebs appeared at basal cell surfaces, and a diffuse pool of fodrin and actin accumulated in them. At the same time, Na+,K+-ATPase moved into the basal membrane subdomain, and extensive endocytosis of basolateral membrane, including Na+,K+-ATPase, occurred. Endocytosis of uvomorulin was not detected and no fodrin was associated with endocytic vesicles. Uvomorulin, along with some membrane-associated fodrin and some Na+,K+-ATPase, remained in the lateral membrane as long as intercellular contacts were maintained. Thus, in this polarized epithelium, interaction of lateral cell-cell adhesion molecules as well as basal cell-substrate interactions are required for maintaining the stability of the lateral membrane skeleton and the position of resident membrane proteins concentrated in the lateral membrane domain.

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