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Biomedical subjects

F E Hossler

Publications and source records attributed to F E Hossler.

28 records · Page 2Linked to original sources
PubMed1983

Morphology of taste buds on the gill arches of the mullet Mugil cephalus, and the killifish Fundulus heteroclitus.

The morphology of taste buds on the gill arches of two euryhaline teleosts, the mullet Mugil cephalus, and the killifish Fundulus heteroclitus, were investigated using light microscopic and scanning and transmission electron microscopic techniques. On the mullet gill arches, taste buds were limited to the pharyngeal surfaces of the smooth-surfaced gill rakers. On the killifish gill arches, taste buds were located on the pharyngeal surfaces of all gill rakers and on the gill arch itself at the bases of the gill rakers. Despite dramatic differences in gill-raker structure between these two species, the taste buds themselves were similar ultrastructurally and closely resembled those described in other fishes. Cells within the taste buds included spindle-shaped dark and light cells and basal cells. Ultrastructural features of both the light and dark cells could support either receptor or transport functions. Tufts of microvilli, including one thick microvillus per light cell and numerous thin microvilli per dark cell, protruded at the apex of each taste bud between the ridged surface epithelial cells. Light cells contained numerous tubular membrane elements some of which appeared to open onto the apical surface of the taste bud. Dark cells contained numerous microtubules and apical, electron-lucent vesicles possibly involved in transport.

Animals↗
PubMed1982

On the mechanism of plasma membrane turnover in the salt gland of ducklings. Implications from DNA content, rates of DNA synthesis, and sites of DNA synthesis during the osmotic stressing and destressing cycle.

This study provides information on the rates of DNA synthesis, sites of DNA synthesis, and DNA content of the avian salt gland during the osmotic stressing (plasma membrane synthesis) and destressing (plasma membrane turnover) cycle, in an effort to better understand the relationship of cell turnover to the initial events in plasma membrane amplification, differentiation, and turnover. The rate of DNA synthesis increases 12--24 h after the onset of osmotic stress, is maximal at about 24 h of osmotic stress, and decreases thereafter in fully stressed and destressed glands. The maximum DNA and protein content, and the maximum protein/DNA ratio are obtained after about 3 days of stress. Autoradiograms show that at 24 hr of stress 70--80% of DNA synthesis occurs in connective tissue cells and 20--30% in parenchymal cells, but by 6 days of stress, synthesis occurs about equally in these cell groups. Because destressing is characterized by a large decrease in plasma membrane and in glandular protein, but by little DNA turnover or loss, the loss of plasma membrane is likely due to some type of cell dedifferentiation rather than cell turnover.

Animals↗
PubMed1980

Gill arch of the mullet, Mugil cephalus III. Rate of response to salinity change.

The rate of response of gill filament epithelium to salinity changes was determined by scanning electron microscopy and biochemical techniques. An increase in Na-K-ATPase content, as measured by [3H]ouabain binding, was detected at 3 h and continued to about 24 h after mullet were transferred from a salinity of 1-4.5%. In contrast, filaments from mullet transferred to freshwater exhibited a decrease in ouabain-binding sites. Similarly, scanning electron microscopy revealed that ultrastructural modifications occurred in epithelial pores of the filament surface in response to salinity changes. These modifications, which included changes in pore diameter and depth and in the number of cellular extensions in the pore's interior, were evident as early as 6 h and were mostly completed by 24 h after the salinity change. Because epithelial pores likely represent apical pits of chloride cells and because the Na-K-ATPase is localized within chloride cells, the present observations likely represent different manifestations of the very rapid response of chloride cells to osmotic stress, and indicate the close association of structure with function.

Adaptation, Physiological↗
PubMed1980

Preparation and characterization of single cells from the avian salt gland.

In preparation for pulse-chase autoradiography experiments and studies of cell surface changes of relevance to plasma membrane biogenesis, we have prepared a cell suspension from the salt gland of ducklings. The method used was a modification of previous methods used for pancreas and salivary gland and included digestions with collagenase and hyaluronidase, divalent cation chelation, and dispersion by gentle pipetting. Yields were 1.13 X 10(7) cells/g gland, and cell recovery was 45% by DNA assay. Recovery of Na,K-ATPase, a marker for salt gland secretory cells was 40--47%. Cell viability was strongly indicated by trypan blue exclusion and 3H-leucine incorporation. Transmission and scanning electron microscopy revealed that most cells retained ultrastructural features characteristic of the intact gland. Smaller cells (3--8 micrometers in diameter), exhibiting few surface microvilli and relatively few cytoplasmic organelles, likely represented the undifferentiated, peripheral cells from the tips of secretory tubules. Larger cells (5--10 micrometers in diameter), exhibiting prominent surface membrane folds enclosing numerous mitochondria, likely represented the functional, secretory cells of the salt gland tubules in various stages of differentiation. The surface folds presented as microvilli and microplicae in scanning electron micrographs.

Animals↗
PubMed1978

Ultrastructural, cyto- and biochemical observations during turnover of plasma membrane in duck salt gland.

The mechanism of plasma membrane turnover was investigated using the duckling salt gland as a model system. Feeding fresh water to salt-stressed ducklings results in a decrease in the Na, K-ATPase in salt gland to non-stressed levels in about 7 days, as measured by ATP hydrolysis and 3H-ouabain binding. Electron micrographs reveal that this is accompanied by a decrease in plasma membrane infoldings on the basal and lateral borders of gland secretory cells. Simultaneously there is an increase in filamentous material and a rise in acid phosphatase and peptidase activities in these cells. Cytochemistry shows that the acid phosphatase activity is mostly associated with the basal or basolateral regions of secretory cells. These ovservations could indicate that the removal of plasma membrane components is accomplished by internalization and digestion within the secretory cells.

Acid Phosphatase↗
PubMed1978

Cytochemical demonstration of sodium, potassium-adenosine triphosphatase by a hemepeptide derivative of ouabain.

A cytochemical probe for the ultrastructural localization of the NaKATPase was devised, which utilizes the biological affinity of the noncompetitive inhibitor, ouabain (ouab) to which was coupled a hemepeptide (H11P) which possesses peroxidatic activity. The conjugate, ouab-H11P, had an apparent Ki of approximately 8 x 10(-7) M. When reacted with fixed tissue from the salt gland of osmotically stressed ducklings, the NaKATPase was localized to the basal and lateral infoldings of the plasma membranes of secretory epithelial cells. Reaction product consisted of fine textured deposits distributed in focal patches on the outer aspects of the membrane. Apical membranes were negative, as were intracellular membrane components. Preincubation of tissue with unlabeled ouabain or binding of ouab-H11P in the presence of 10 mM K+, no ATP and no Mg++, resulted in the absence or diminution of reaction product.

Animals↗
PubMed1978

Ouabain binding during plasma membrane biogenesis in duck salt gland.

The conditions necessary for optimal ouabain binding in the avian salt gland were examined. Binding was enhanced by ATP and Mg2+ and was decreased by K+, but was unaffected by added Na+. Both maximal binding and complete inhibition of Na, K-ATPase activity were obtained at 1 X 10(-6) M ouabain. Half maximal binding and half maximal inhibition of Na, K-ATPase activity were obtained at 1.7 X 10(-7) M ouabain. Ouabain binding increased in parallel with increasing specific activity of the Na, K-ATPase duringsalt-induced salt gland specialization. The ratio of Na, K-ATPase activity to ouabain-binding sites remained constant during the salt stress as well as after removal of the salt diet. Autoradiography indicated binding to partially and fully differentiated secretory cells of the salt gland. The ouabain binding assay appeared to be a more useful indicator of membrane amplification than Na, K-ATPase activity since it is rapid, essentially irreversible, less sensitive to tissue fixatives, and quantitatively measured the number of enzyme molecules.

Adenosine Triphosphatases↗
PubMedDate not supplied

Vasoconstrictor and dilator responses to neurokinin A in isolated guinea pig heart.

Effects of neurokinin A (NKA) and substance P (SP) on coronary resistance vessels were studied in isolated guinea pig hearts perfused with isotonic buffer containing 20 mM KCl. Injections of NKA and SP caused dose-dependent reductions in perfusion pressure with ED50 values of 14.0 and 0.326 pmol, respectively. Blockade of nitric oxide synthesis or removal of the endothelium inhibited vasodilator responses to neurokinins. Infusions of NKA or SP caused tachyphylaxis and cross-desensitization to the other neurokinin but not to acetylcholine. Injections of 2.5 nmol NKA increased perfusion pressure by 31 +/- 8% when given after tachyphylaxis developed to infused SP (2.5 nmol/100 microliters/min). It was concluded that 1) neurokinins cause an endothelium-dependent relaxation of coronary resistance vessels by stimulating NK-1 receptors on endothelial cells, and 2) desensitization of the receptor mediating vasodilation unmasks a vasoconstrictor response to NKA.

Animals↗