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PubMed1995

Ostrich pepsinogens I and II: purification, activation and chemical and immunochemical characterization of the enzymes from the proventriculus.

Pepsins are a series of gastric proteases secreted as inactive precursors (pepsinogens) which are active at acidic pH. The aim of this study was to purify ostrich pepsin(ogen)s and to compare their biochemical and immunological characteristics with those of pepsin(ogen)s of mammalian and avian origin. Ostrich pepsinogens were purified by ammonium sulphate fractionation, Toyopearl Super Q-650S chromatography and rechromatography, and hydroxylapatite chromatography of a pH 8.0 mucosal extract. Pepsins were obtained through acidification, and purified by chromatography on SP-Sephadex C-50. Amino acid compositions, N-terminal sequences, Ouchterlony double-diffusion as well as Western blot analysis were performed. Two pepsinogens were isolated and purified from the proventriculus of the ostrich, pepsinogens I and II. Both pepsinogens and pepsins were purified to homogeneity as shown by PAGE and SDS-PAGE, with SDS-PAGE revealing M(r) values of 40,400 and 41,900 for pepsinogens I and II, respectively. SDS-PAGE revealed M(r) values of 36,000 and 36,300 for ostrich pepsins I and II, respectively. Ostrich pepsinogens I and II were found to have identical N-terminal sequences, with Asp as N-terminal amino acid. Amino acid compositions were obtained for both pepsinogens, with ostrich pepsinogen I being slightly smaller in size with a total of 356 residues compared to 371 for ostrich pepsinogen II. Pepsinogen II showed a pI of 4.29. Ostrich pepsinogens I and II were found to be immunologically separate entities, and no cross-reactivity was observed between anti-(ostrich pepsinogen I/II) sera and porcine pepsin/pepsinogen. The study indicates that only two pepsinogens are present in the ostrich. They differ in terms of electrophoretic mobility, molecular mass and immunological reactivity, but have been found to have identical N-terminal sequences. It is concluded that both pepsinogens belong to the pepsinogen A class of aspartyl proteases (EC 3.4.23.1).

Amino Acid Sequence↗
PubMed1987

Effect of gizzerosine on acid secretion by isolated mucosal cells of chicken proventriculus.

Mucosal cells of the chicken proventriculus were isolated by a collagenase perfusion method and O2 uptake by the isolated cells was measured as an index of the activity of gastric acid secretion. Oxygen consumption was enhanced by histamine; this effect was augmented by the coexistence of isobutylmethylxanthine, an inhibitor of cyclic adenosine 5.-monophosphate (AMP) phosphodiesterase, and suppressed by imidazole, an activator of the enzyme. The action of histamine was inhibited by cimetidine, an antagonist of the histamine H2 receptor. These results indicate that the isolated cells retained the capacity to take up O2, responding to histamine via the H2 receptor and probably the cyclic AMP level. Gizzerosine (2-amino-9-(4-imidazolyl)-7-azanonanoic acid) also stimulated O2 consumption by the isolated cells. The effect of gizzerosine was cancelled by cimetidine, suggesting that the mechanism by which gizzerosine acts on the mucosal cells is similar to that of histamine action. These observations are consistent with our previous presumption that gizzerosine causes gizzard erosion by enhancing gastric acid secretion in chickens.

Animals↗
PubMed1975

The occurrence of lipid in the oxyntico-peptic cells of the proventriculus of the fasting domestic fowl.

A histological study has shown that considerable amounts of lipid accumulate in the oxyntico-peptic cells of the proventriculus of domestic fowls deprived of food. Lipid droplets were first seen in the cells 6 hours after commencing the fast and they reached a maximum in 24 hours; a decrease was detected histologically 2 hours after re-feeding and all lipid had disappeared 8 hours after access to food. Lipid was observed in fasted chickens aged from 1 to 27 weeks, in four different breeds, and in certain naturally occurring diseases. Small amounts of lipid were also seen in the proximal convoluted tubules of the kidneys of chickens which had been fasted. The relationship of the lipid to the metabolism of the oxyntico-peptic cells and to certain disease states is discussed.

Animals↗
PubMedDate not supplied

Characterization of a gram-positive bacterium from the proventriculus of budgerigars (Melopsittacus undulatus).

The cellular, cultural, and biochemical characteristics of eight isolates of a large gram-positive bacillus that are commonly observed as apparently normal flora in the proventriculus of budgerigars (Melopsittacus undulatus) were determined. The bacterium was highly pleomorphic and changed markedly in both diameter and length when subcultured on agar media. The bacterium was facultative anaerobic and capnophilic, hemolytic on blood agar, and formed flat colonies with irregular edges after incubation for several days. All isolates grew on sodium azide agar but did not grow on MacConkey agar. The isolates were catalase-negative and oxidase-negative and did not reduce nitrate. All isolates failed to utilize arginine, lysine, ornithine or tryptophane but produced acid from glucose, galactose, levulose, maltose, melibiose, starch, and sucrose. All isolates produced acetoin from glucose and hydrolyzed esculin. The eight isolates could not be identified to either genus or species level based on the descriptions of currently classified organisms in the division Firmicutes as described in Bergey's Manual of Systematic Bacteriology.

Animals↗
PubMed1990

Use of lectins for detection of glycoconjugate changes in mucous epithelium of the chicken proventriculus.

The lectin binding pattern in the mucous epithelium of the chicken proventriculus was studied by using a peroxidase labeling method and correlated procedure. The nature of glycoconjugates in the mucous epithelium was found to change during the upward cell migration from deep to superficial parts. The superficial mucous epithelium (plica) was found to contain predominantly neutral glycoconjugates with N-acetyl-D-glucosamine residues and terminal galactose-N-acetylgalactosamine disaccharides whereas the deep epithelium (sulcus) contained acidic sulfated glycoconjugates with terminal sialic acid-galactose dimer. A continuous intraluminal mucous layer over the surface epithelium was found to contain a mixture of glycoconjugates secreted from both the plica and sulcus mucous cells. The data suggests that the changes in glycoconjugates of epithelial cells were closely correlated with cellular maturation.

Animals↗
PubMed1983

The endocrine cells of the chicken proventriculus.

The endocrine cells of the chicken proventriculus were investigated by selective staining techniques, immunohistochemistry and electron microscopy. The following endocrine cell types were identified: 1) Argyrophilic ECL-cells, of unknown function, were very numerous in the 21-day-old chick, but less numerous in the newborn chick; 2) somatostatin-producing D-cells; 3) GLI-cells producing glucagon-related peptides; 4) X-cells of unknown function; 5) BN-cells producing bombesin; and 6) relatively few 5-hydroxytryptamine-producing EC-cells. Each of these cell types show a distinct morphology, distribution and histochemical reactivity. With the exception of BN-cells, they resemble rather closely the corresponding endocrine cell types previously described in the oxyntic mucosa (EGL, D, X and EC cells) or in the intestinal mucosa (L-cells) of the mammalian gut.

Animals↗
PubMed1984

Ontogenesis of bombesin-like immunoreactive cells in the chicken proventriculus.

The distribution and morphological behaviour of bombesin like immunoreactive cells in the proventriculus of chick embryos, newborns and adults were investigated by indirect immunoperoxidase procedure. The first immunoreactive cells appear around the 11th day of incubation. Initially few, they increase progressively to reach a peak around the 18th day. Throughout the embryonic period almost all immunoreactive cells are column-shaped, display a typical "open" behaviour, and are situated among other superficial lining epithelial cells. Around hatching time, these "open" cells suddenly decrease in number while another immunoreactive "closed" cell type becomes more evident in a deeper location. In newborns and adults, the majority of immunoreactive cells are oval shaped and are characteristically situated near the neck of lobular glands; they seem to display a "closed" behaviour. The results demonstrate two different kinds of peptide-containing cells which probably exert different functions. During the embryonic period, in fact, they resemble a chemioreceptor, but in postnatal life they appear as a paracrine/endocrine elements.

Animals↗
PubMed1984

Tetrameres columbicola (Nematoda: Spiruridae) infection of pigeons: ultrastructure of the gravid female in glands of the proventriculus.

The light and electron microscopies of Tetrameres columbicola gravid females in sections of the parasitized proventriculus of pigeons were studied. By light microscopy, the most conspicuous structures in the sectioned parasite were the intestine, ovary, and especially the uterus that contained numerous eggs. By electron microscopy, there was a thick mat of pigment-coated microvilli on the surfaces of the intestinal epithelial cells. The germinal zone of the ovary contained nonmembrane-bound oocytes, but oocytes were confined by a membrane in the growth zone of the ovary. The core of the spermatheca contained oocytes and the periphery harbored sperm. In this location, the unfertilized oocyte had pseudopods; sperm had invaginations of the plasma membrane. After fertilization, there was proliferation of ribosomes within the oocyte. Embryonating eggs in the uterus had thick shells and were partially enveloped by elongations of the uterine epithelial cells. Surfaces of the epithelial cells were pleated and they had electron opaque areas at the points of the pleats. Larvae in eggs had a well developed annulated cuticle and muscular layer. Somatic muscle cells had tailed appendages that protruded into the pseudocoelom. The single layer of cells beneath the hypodermis had lateral processes at the base of the cells that interdigitated with similarly elongated processes of adjacent muscle cells. Striated fibers were present in the central portion of the cells.

Animals↗
PubMed1992

Ca2+-ATPase in mucous and oxyntico-peptic cells of the fowl proventriculus.

Calcium adenosine triphosphatase (Ca(2+)-ATPase) was localized by means of histo-and ultracytochemistry in the secretory cells of the proventriculus of the domestic fowl. The mucous cells exhibited plasmalemmal-associated enzyme activity on the external aspect of the basolateral cell membrane. Intracellularly, the luminal aspect of Golgi-membranes and of secretory vesicle membranes reacted positively for Ca(2+)-ATPase activity, as did the apical cytosol and the matrix of lysosomes. Oxyntico-peptic cells were characterized by apical and apico-lateral plasmalemmal activity and by an organelle-associated distributional pattern similar to that in the mucous cells. In addition, Ca(2+)-ATPase was associated either with the matrix of mitochondria or with tubuli of the rough-surfaced endoplasmic reticulum. The results are discussed with respect to messenger and effector functions of calcium in the process of proventricular mucus secretion. In addition, Ca(2+)-ATPase distributional patterns in the oxyntico-peptic cell are related to the unique structure and function of these cells.

Animals↗
PubMed1985

Dilated cisternae of nuclear envelope and rough endoplasmic reticulum in the proventriculus of Drosophila auraria larvae.

In the cells of the middle layer of the proventriculus of Drosophila auraria larvae, the nuclear envelope and the rough endoplasmic reticulum are always found in the form of dilated cisternae. The length of these cisternae can reach 10 mu. There are indications that materials from the outer membrane of the nuclear envelope are directly transported to the Golgi complex of the examined cells.

Animals↗
PubMed1972

Proventriculus of a marine annelid: muscle preparation with the longest recorded sarcomere.

EACH MUSCLE OF THE SYLLID (ANNELIDA: Polychaeta) proventriculus, the region of the gut posterior to the pharynx, contains a single zigzagging Z band, flanked on each side by a sequence of I-A-H-A-I bands defined by thick (60-90 nm) and thin (5 nm) filaments. The thick filaments show a 14-nm periodicity similar to paramyosin. The muscle cell terminates at the level of the outer I bands. The muscle does not include a complete sarcomere in the strict sense, as defined by a pair of Z bands, but the equivalent H-H distance reaches about 40 mum. Electrophysiological evidence suggests that contraction and relaxation of the cell are, respectively, associated with depolarizing and hyperpolarizing potentials.

Animals↗
PubMed1986

Ontogenesis of 5-hydroxytryptamine-like immunoreactive cells and their relationship with bombesin in chicken proventriculus.

By using a double-stain immunohistochemical procedure, the Aa. studied the onset, the behaviour and the possible interrelationship between the 5-HT-like and bombesin-like immunoreactive cells during the ontogenesis of chicken proventriculus and in adult animals. The 5-HT-like immunoreactive cells become evident from the 8th day of incubation and they reach their peak around the 16th day, then markedly decrease at hatching. In adult animal these cells are always present, but are not so numerous. Between the 14th and the 18th day many double-stained cells scattered among other only 5-HT or bombesin-like immunoreactive cells are present. They can also be observed in adults, but only occasionally.

Animals↗
PubMed1985

Histopathological changes in the proventriculus of fowl given experimental monospecific infection with Acuaria spiralis.

The pathological changes in the proventriculi of fowls given monospecific experimental infection with Acuaria spiralis were characterized in the initial stages by an acute inflammation due to the migration of 3rd and 4th stage larvae. There was a severe non-keratinizing squamous cell metaplasia of the lining epithelium with pronounced granulocytic infiltration at 4-8 days post-infection. Multiple lymphoid nodules were evident in the lamina propria from 12 days post-infection. As the disease progressed there was extensive fibroplasia in the organ. By 50-100 days post-infection pedunculated fibro-adenamatoid growths developed in the mucosa obliterating the entire lumen of the organ. A mortality rate of 29.16% of chicks (maximum on the 3rd week post-infection) was observed.

Animals↗