Eta Cells Research Articles

Electric-field assisted spray technique for controlled pore filling of nanostructured films: device applications

A novel pore-filling system was prepared using spray as the key-technique, for solar cells and various other applications. High performance in perovskite, dye-sensitized and eta cells is often achieved using metal oxide layers or their mesoporous analogues. One dimensional scaffold materials such as nanorods or nanotubes are also employed in order to improve charge collection. Herein, we introduce a method to more efficiently fill the pores in the most common nanostructure architecture namely mesoporous, nanorods or nanotubes. The method employs the use of spray technique with applied DC voltage (through two different voltage supplies) as the cost-effective technology for time efficient pore filling. SnS nanoparticles and N719 dye have been pore-filled onto a previously deposited ZnO nanorods and mesoporous TiO2 film, respectively, using the novel setup. Scanning electron microscopy images revealed an improved pore-filling, the complementary enhancement of ~ 24% in the DSSC efficiency and ~ 16% and 7% in terms of current density and fill factor, respectively has been found in comparison to the reference standard device. It is attributed to an increase in the concentration of dye molecules into the pores of TiO2 nanostructures due to better dye loading and hence observed an improvement in light absorption, electron transportation and charge collection. This pioneer pore filling technique exponentially reduced the dye loading time duration from overnight immersion of photo anodes in dye solution to 15–20 min.

Fabrication of ETA cells based on ZnO/CuInS2 core/shell heterostructure

ZnO/CuInS2/CuSCN heterostructure was synthetised using ZnO/CuInS2 core/shell nanorods array as substrate via a low cost electrodeposition method. The as obtained heterostructure could be considered as the main part of typical extremely thin absorber solar cell, since the ZnO nanorods and CuInS2 layer would serve as the electronic delivery material and light absorber, while the β-CuSCN would play the role of hole conductor. The as obtained heterostructure shows a high absorbing capacity in the visible part of the solar spectrum with a light absorption centre located at ∼550 nm, and the efficiency of the solar cells was measured to be 0.16% using Au as counter electrode.

Tectal neurons signal impending collision of looming objects in the pigeon

Although the optic tectum in non-mammals and its mammalian homolog, the superior colliculus, are involved in avoidance behaviors, whether and how tectal neurons respond to an object approaching on a collision course towards the animal remain unclear. Here we show by single unit recording that there exist three classes of looming-sensitive neurons in the pigeon tectal layer 13, which sends looming information to the nucleus rotundus or to the tectopontine system. The response onset time of tau cells is approximately constant whereas that for rho and eta cells depends on the square root of the diameter/velocity ratio of objects looming towards the animal, the cardioacceleration of which is also linearly related to the square root of this ratio. The receptive field of tectal cells is composed of an excitatory center and an inhibitory periphery, and this periphery does not inhibit responses to looming stimuli. These results suggest that three classes of tectal neurons are specified for detecting an object approaching on a collision course towards the animal, and that rho and eta cells may signal early warning of impending collision whereas tau cells initiate avoidance responses at a constant time before collision through the tectopontine system.

O0041 HES1, A TRANSCRIPTIONAL REPRESSOR, CONTROLS BILIARY VERSUS PANCREATIC DEVELOPMENT

Introduction: The biliary system, pancreas and liver all develop from the nearby fetal gut at almost the same time. However, the molecular mechanisms that determine the identity of each organ are unknown. Hes1 encodes the basic helix-loop-helix protein Hes1, which represses positive basic helix-loop-helix genes such as Neurogenin3. Expression of Hes1 is controlled by the evolutionarily conserved Notch pathway. Mutations in JAG1, encoding a Notch ligand, cause the Alagille syndrome, characterized by poor development of the biliary system, suggesting that the Notch pathway is involved in normal biliary development. In this study, we show that Hes1 acts like a molecular switch between biliary and pancreatic development. Methods: We examined the biliary system and other foregut-derived organs during embryogenesis in Hes1-deficient and wild-type mice. Results:Hes1 is expressed in the extrahepatic biliary epithelium throughout development and that Hes1-deficient mice show gallbladder agenesis and severe hypoplasia of extrahepatic bile ducts, although the intrahepatic bile ducts develop distinctly in the mutants. We did not find an increase in apoptotic cells in the mutant compared with wild-type biliary epithelium. The biliary epithelium in Hes1-deficient mice ectopically expresses the pro-endocrine gene Neurogenin3 and differentiates into endocrine cells, expressing glucagon (alpha cells), insulin (??eta cells), somatostatin (delta cells) and pancreatic peptide (PP-cells) and exocrine cells. The ectopic insulin-positive cells also co-expressed Ipf1, Isl1 and glut2, similarly to mature pancreatic ??eta cells. The mutant bile ducts also displays pancreatic morphology with the formation of acini and islet-like structure and thus the common bile duct of Hes1-deficient embryos was totally replaced by pancreatic tissue. Conclusion: Biliary epithelium has the potential for pancreatic differentiation and Hes1 determines extrahepatic biliary organogenesis by preventing the pancreatic differentiation program, most likely involving direcly repressing transcription of Neurogenin3.

The activation of the phosphotyrosine phosphatase eta (r-PTP eta) is responsible for the somatostatin inhibition of PC Cl3 thyroid cell proliferation.

The aim of this study was the characterization of the intracellular effectors of the antiproliferative activity of somatostatin in PC Cl3 thyroid cells. Somatostatin inhibited PC Cl3 cell proliferation through the activation of a membrane phosphotyrosine phosphatase. Conversely, PC Cl3 cells stably expressing the v-mos oncogene (PC mos) were completely insensitive to the somatostatin antiproliferative effects since somatostatin was unable to stimulate a phosphotyrosine phosphatase activity. In PC mos cells basal phosphotyrosine phosphatase activity was also reduced, suggesting that the expression of a specific phosphotyrosine phosphatase was impaired in these transformed cells. We suggested that this phosphotyrosine phosphatase could be r-PTP eta whose expression was abolished in the PC mos cells. To directly prove the involvement of r-PTP eta in somatostatin's effect, we stably transfected this phosphatase in PC mos cells. This new cell line (PC mos/PTP eta) recovered somatostatin's ability to inhibit cell proliferation, showing dose-dependence and time course similar to those observed in PC Cl3 cells. Conversely, the transfection of a catalytically inactive mutant of r-PTP eta did not restore the antiproliferative effects of somatostatin. PC mos/PTP eta cells showed a high basal phosphotyrosine phosphatase activity which, similarly to PC Cl3 cells, was further increased after somatostatin treatment. The specificity of the role of r-PTP eta in somatostatin receptor signal transduction was demonstrated by measuring its specific activity after somatostatin treatment in an immunocomplex assay. Somatostatin highly increased r-PTP eta activity in PCCl3 and PC mos/PTP eta (+300%, P < 0.01) but not in PCmos cells. Conversely, no differences in somatostatin-stimulated SHP-2 activity, (approximately +50%, P < 0.05), were observed among all the cell lines. The activation of r-PTP eta by somatostatin caused, acting downstream of MAPK kinase, an inhibition of insulin-induced ERK1/2 activation with the subsequent blockade of the phosphorylation, ubiquitination, and proteasome degradation of the cyclin-dependent kinase inhibitor p27(kip1). Ultimately, high levels of p27(kip1) lead to cell proliferation arrest. In conclusion, somatostatin inhibition of PC Cl3 cell proliferation requires the activation of r-PTP eta which, through the inhibition of MAPK activity, causes the stabilization of the cell cycle inhibitor p27(kip1).

Gene expression of bone matrix proteins and endothelin receptors in endothelin-1-deficient mice revealed by in situ hybridization.

Endothelin-1 (ET-1) was first found as a vasoconstrictor protein excreted by vascular endothelial cells, but recently ET-1 has been considered to have widespread functions that include regulation of osteochondrogenic metabolism. We analyzed sections of head regions in ET-1 knockout mice that are known to have abnormalities in pharyngeal arch-derived tissues and found that there was severe hypoplasia in facial bones. The hypoplasia suggests that the matrix mineralization system of facial bones is disrupted in ET-1-/- homozygous mice. To elucidate whether osteogenic cells in facial bones are the targets for ET-1 and whether expression of bone matrix genes are modulated by ET-1, we examined gene expression of ET-1 receptors, ETA and ETB, and that of the bone matrix proteins, osteonectin (ON) and osteopontin (OP), both in the head regions of ET-1+/- heterozygous and ET-1-/- homozygous mice by means of in situ hybridization. Different patterns of expression between ETA and ETB mRNAs were observed in both groups. In 18.5 days post coitus fetuses, ETA mRNA was most strongly expressed in osteogenic cells along craniofacial bones, but ETB mRNA was most strongly expressed in trunks of trigeminal nerve. This finding suggests that ET-1 may modulate osteogenic cells through ETA receptor but not through ETB receptor. The expression patterns of ETA, OP, and ON mRNAs were distinct between the two groups. In the lower jaw of ET-1+/- heterozygous mice, the ETA, ON, and OP mRNA positive cells were scattered in the inner and outer regions of the thick bone matrix, but in ET-1-/- homozygous mice, cells containing those mRNAs were located close to each other at the surface of thin bone matrix. However, cellular expression of ON and OP mRNAs in osteogenic cells of ET-1-/- homozygous mice was not suppressed as compared with ET-1+/- heterozygous mice. We conclude that ET-1 may regulate proliferation and migration of osteogenic cells in the maxillofacial region, rather than modulating the expression level of ON and OP mRNAs.

Endothelins stimulate mitogen-activated protein kinase cascade through either ETA or ETB

Endothelin (ET) has been shown to activate mitogen-activated protein kinase (MAPK). However, it has been unclear which of the ET receptors is coupled to MAPK activation. In the present study, we conducted experiments to determine which ET receptor is linked to MAPK activation. We found that both human ETA and ETB were coupled to the MAPK cascade in ETA or ETB cDNA-transfected Chinese hamster ovary cells. ET-1 was more potent than ET-3 in the activation of p42 MAPK, induction of MAPK kinase (MAPKK) gel retardation and uptake of [3H]thymidine in ETA-transfected cells, whereas sarafotoxin (S6c) showed no stimulatory effect on the kinases and [3H]thymidine uptake. ET-1, ET-3, and S6c had approximately the same potency to activate p42 MAPK, MAPKK gel retardation, and [3H]thymidine uptake in ETB-transfected cells. These data suggest that 1) ET isopeptides, through either ETA or ETB receptors, induce the MAPK cascade as well as cell proliferation; and 2) the different potencies of ET isopeptides for activation of the MAPK cascade and induction of cell growth are mainly due to their different affinities toward ETA and ETB.

Inhibition of Lewis lung tumor growth and metastasis by Ehrlich ascites tumor growing in the same host.

A double tumor model (3LL and EAT) was established in C57BL/6 mice. The primary 3LL tumor was growth-inhibited by EAT inoculated into the same host. Growth inhibition of the 3LL primary tumor depended on the number of EAT cells injected. Inhibition of the growth of the primary 3LL tumor was also observed after injection of the optimal number (10(7)) of EAT cells 24 h to 7 days before or after inoculation of 3LL cells. In contrast, metastasis of the 3LL tumor was only inhibited after simultaneous inoculation of 3LL and ETA cells. Moreover, EAT cells inhibited the growth of preformed 3LL-derived metastases after resection of the primary 3LL tumor. Although the EAT-induced stimulation of a host defense system is not excluded, the results are consisted with the continued release of growth inhibition factors from EAT cells acting on 3LL cells in the primary tumor and in lung metastases.

Uptake of tritiated leucine by the prolactin cell follicles of the coho salmon, Oncorhynchus kisutch.

Uptake of tritiated leucine during various time intervals by prolactin cell follicles of coho salmon (Oncorhynchus kisutch) acclimated to 30‰ artificial seawater was studied. Labelling in eta cells from fish transferred to freshwater immediately after injection was higher than in fish remaining in 30‰ seawater. Grains in individual eta cells were evenly distributed with the exception of some follicles where there were higher concentrations at the apical ends. This was interpreted as indicating the initial stage of active incorporation of leucine in the juxtaluminar region. Freshwater fish exhibited not only higher grain density but also apical grain concentration at earlier times than seawater fish, suggesting faster uptake and (or) incorporation of leucine, and therefore presumably of prolactin production, in the freshwater fish. No labelling was found in the follicular lumina except when hematoxylin-stained bodies were found in the lumina of adjacent sections of stained follicles. The significance of these bodies is unknown but it appears unlikely that the lumina are involved with the synthesis of prolactin.

Prolactin and growth hormone cells in the human hypophysis: a study with immunoenzyme histochemistry and differential staining.

Growth hormone and prolactin cells were immunostained in human hypophyses with antibody against rat growth hormone or prolactin and the peroxidase-antiperoxidase complex. Growth hormone cells were round and, in normal pituitaries, arranged in sizable groups. Prolactin cells occurred singly and were less numerous; they were often extensively branched. Only a few prolactin cells stained with carmoisine. Incubation of the antibody with an excess of the appropriate antigen greatly diminished or abolished immunostaining; absorption of anti-prolactin with growth hormone often enhanced it. Prolactin cells were somewhat hypertrophied and hyperplastic in a neonate. Many of them stained with carmoisine. An even greater hypertrophy and hyperplasia of these cells (which pushed apart the growth hormone cells) was found in a lactating woman. Immunostained giant prolactin cells were also observed. Staining of the prolactin cells with carmoisine was extensive. Upon prolonged exposure to anti-growth hormone antibody, ACTH/MSH cells also showed immunostaining which was abolished by absorption of the antiserum with growth hormone but not with synthetic 1-24ACTH. Growth hormone cells evidently correspond to the alpha acidophils of Romeis, prolactin cells in lactation to his eta cells; the relation of his epsilon cells to the pleomorphic "resting" prolactin cells is not clear.

The pituitary of Aphanius dispar (Rüppell) and its neurosecretory innervation from hypersaline marshes and fresh water. I. The rostral pars distalis.

Eta cells of the pituitary of Aphanius dispar specimens adapted to sea water are densely packed and have folded nuclei. Unfolding of the nuclei accompanied by cellular hypertrophy and hyperplasia was observed 24 hours after experimental transfer of specimens into fresh water. In specimens from natural habitats and adapted over long periods to fresh water, the nuclei are rounded and cellular hypertrophy attains maximal values. Dilatation of capillaries in the hypophysis was observed in about one third of the specimens within the first few days after transfer to fresh water. In specimens adapted either to fresh water or to sea water the capillaries were normal. Epsilon cells from seawater specimens have elongated nuclei perpendicular to the basement membrane which separates the rostral neurohypophysis from the adenohypophysis; in freshwater specimens epsilon cell nuclei are rounded.

Activity of autotransplanted pituitary glands in goldfish, Carassius auratus L., maintained in different ambient salinities

Pituitary histology was compared in in situ and autotransplanted glands in goldfish which were acclimated to four different ambient media. In addition, the histology of the gonad and interrenal and thyroid gland and plasma Na+ and K+ concentrations were examined in these fish as well as in hypophysectomized animals acclimated to the same external media.The rostral pars distalis (RPD) epsilon cells, presumptive proximal pars distalis (PPD) thyrotrophs, and pars intermedia (PI) PAS stainable (+ve) cells appear to function only with intact hypothalamic–adenohypophysial connections whereas the remaining pituitary cell types were independent of hypothalamic control and in some cases (RPD eta cells and basophil cells) were directly affected by environmental salinity.The thyroid epithelial cell height (TEH) was elevated in all the groups of fish in 30% seawater. The significant (albeit small) rise in pharyngeal TEH in hypophysectomized animals in 30% seawater may indicate a direct effect of the ambient environment on thyroid gland activity.The interrenal cell nucleus diameter was not significantly affected by any of the treatments although cytological changes were found in the interrenal cells in hypophysectomized and to a lesser extent in autotransplanted fish, which indicated a lower activity in these groups when compared with shamoperated controls; there was no apparent effect of salinity on interrenal cell activity.Plasma Na+ concentrations were not maintained in fish with autotransplanted pituitaries acclimated to hypotonic media (distilled and tap water); thus the viability of endocrine factors which regulate plasma Na+ levels in the goldfish appears to be impaired in these fish.

Immunohistochemical localization of prolactin in the pituitary gland of the pigeon, Columba livia.

Specific antibodies to ovine prolactin were produced in rabbits. The antisera were conjugated to fluorescein isothiocyanate and "purified" by column chromatography. Antibodies, thus labelled, were applied to fresh-frozen sections of pigeon pituitary glands. Fluorescence was observed in specific cells of the cephalic lobe. After staining, these cells were identified as the erythrosinophilic eta cells.

The ultrastructure of the cell types and of the neurosecretory innervation in the pituitary of Mugil cephalus L. from fresh water, the sea, and a hypersaline lagoon : I. The rostral pars distalis

The ultrastructure of the cells of the rostral pars distalis and their neurosecretory innervation were studied in the pituitaries of Mugil cephalus from fresh water (FW), the sea (SW), and a hypersaline lagoon (HL). The secretory granules of the eta cells have a median diameter of 2600 Å in FW, 2300 Å in SW, and 1800 Å in HL. Large-sized nucleus and nucleolus, a well developed endoplasmic reticulum, and abundance in secretory granules in FW eta cells were interpreted as indicating high synthetic activity, while scarcity of granules, decrease of cellular size as well as reduction of the volume of the RPD in HL specimens were interpreted as indicating high release and inadequate synthesis. An intercellular channel system formed by specialized channel cells in the eta cell region is described. In the epsilon cell region, a channel system is formed by invaginating membranes of the epsilon cells. Neurosecretory granules in the rostral neurohypophysis are of two types: (1) presumably peptidergic, which accompany the capillaries and probably most of them empty into the capillaries before the latter penetrate the epithelial region; and (2) presumably aminergic granules which are close to the interface which separates the neurohypophysis from the rostral pars distalis. Neurosecretory elements in the adenohypophyseal region between the eta cells, are of the aminergic type. The possible roles of the different neurosecretory granules are discussed.

The influence of environmental salinity on the prolactin- and gonadotropin-secreting regions in the pituitary of Mugil (Teleostei)

Specimens of two species of Mugil were collected from three environments differing in salinity (freshwater, seawater, and a hypersaline lagoon). Volumetric and histological changes in the proximal and rostral pars distalis of pituitaries from these fish are described. The most pronounced changes occur in the size of the rostral pars distalis of M. capito. This lobe (whose main component is the prolactin-secreting region) varies, occupying from 8% of the total hypophysis in fish from the hypersaline lagoon (7.8% salinity), to 42.6% in fish from freshwater. This increase in the size of the rostral pars distalis is accompanied by an increase in the size and granular content of individual eta cells. The volumetric changes of the proximal pars distalis are the inverse of those of the rostral pars distalis. Proximal pars distalis changes were most pronounced in M. cephalus, where this lobe occupies 35% of the hypophysis in specimens collected from the Mediterranean Sea during the spawning season, as compared with 7.3% of the hypophysis in specimens collected from freshwater. The prolactin content of the pituitary in M. cephalus as assayed by the water-drive test in Triturus vulgaris and T. alpestris is high in the freshwater specimens and low or almost nonexistent in specimens collected from the sea. Striking histological changes, possibly indicative of a degenerative process, are observed in the nucleus lateralis tuberis of M. cephalus specimens confined to freshwater for several years. These changes and their relationship to the volumetric variations of the rostral and proximal pars distalis of the pituitary are discussed. Data on the mucous and chloride cells of the gills as well as on the sodium plasma level are presented.

Seasonal variation in the structure and ultrastructure of the pituitary of the marine form (Trachurus) of the threespine stickleback, Gasterosteus aculeatus L. I. Rostral pars distalis.

The rostral pars distalis of the anadromous marine stickleback Gasterosteus aculeatus L., form trachurus is composed of three distinct cell types, eta (prolactin-secreting), epsilon (corticotroph) and chromophobic cells. The epsilon and eta cells appear minimally active in early-winter fish collected in the sea and maximally active in spring fish collected in fresh water. Similarly, the chromophobes are least developed in the winter stages and maximally developed in spawning fish. Two possible mechanisms of hormone release were observed in the eta cells of spring fish collected in fresh water, but these were absent from the stages collected in or transferred to sea water. The mode of regulation of eta cell activity is discussed.

Immunohistochemical Localization of ACTH and Prolactin in the Pituitary Gland of Adult Migratory Sockeye Salmon (Oncorhynchus nerka)

Antibodies to porcine adrenocorticotrophic hormone (ACTH), Synacthen (synthetic corticotrophin, Ciba), and ovine prolactin were prepared in rabbits and the antisera were tested for specificity against several pituitary hormones. The gamma-globulin fractions of the antisera were conjugated with fluorescein isothiocyanate and the labelled antibodies were "purified" by column chromatography.Fresh-frozen sections of pituitary glands of adult migratory sockeye salmon were incubated with the antibody solutions and examined with a fluorescence microscope. The resulting antigen–antibody complex could be localized by re-photographing the same or alternate sections after fixation and staining. Anti-ACTH and anti-Synacthen appeared to be bound specifically by the epsilon cells, whereas anti-prolactin reacted with the eta cells of the rostral pars distalis. Pituitary glands collected at various stations along the migratory route, including one seawater sample, showed the same reactivity. Other glands were prepared for histological examination. Microspectrophotometric analysis of cell types showed that the granule density of the ACTH cells increased gradually during the later part of migration. In the prolactin cells, no change in granulation could be detected during entrance into the river or subsequent spawning migration.

Response of “prolactin-secreting” cells of Tilapia mossambica to environmental salinity

The cytological changes of the eta (“prolactin”) cells in the pituitary of Tilapia mossambica due to changes in environmental salinity have been described at both the light- and electron-microscope levels. In fish maintained in fresh water, the eta cells in the well-developed rostral lobe are large and contain many large secretory granules. A prominent Golgi system in addition to a multilayered endoplasmic reticulum suggests a high level of secretory activity. On the other hand the rostral lobe is smaller in seawater fish and the eta cells appear condensed, the organelles as well as granule size are reduced suggesting a diminished synthetic activity. The possible role of the secretion of eta cells in the osmoregulation of fishes is discussed.

Localization of prolactin within the pituitary of a cyprinodont fish, Fundulus heteroclitus (Linnaeus), by specific fluorescent antiovine prolactin globulin

Precipitin reactions in vitro have shown that antibody to ovine prolactin is capable of binding ovine prolactin and a prolactin-like fraction prepared from the pituitary glands of the carp ( Cyprinus carpio) and the pollack ( Pollachius virens). It seems reasonable to postulate that it would also bind prolactin of other teleosts. Hence the globulin fraction of antiovine prolactin serum was bound to fluorescein isothiocyanate, purified, and the antibody solution used to localize prolactin within sections of frozen pituitary of Fundulus heteroclitus. Sections so prepared show the presence of green fluorescent antigen-antibody complex only in the acidophils of the rostral pars distalis. Control staining with fluorescent normal globulin failed to give this result. Serial sections adjacent to the fluorescent antibody-treated preparaions were stained histologically and the erythrosinophilic eta cells identified as those which contain prolactin. Since no other cells of the pituitary gave these reactions it can be concluded that the eta cells are the prolactin cells. Similar preparations from the pituitaries of fresh water adapted fundulus show that in the enlarged rostral zone the erythrosinophilic eta cells contain prolactin.