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Developmental expression and spatial distribution of dopa decarboxylase in Drosophila.

Regulation of the dopa decarboxylase gene of Drosophila has been studied at the genetic and molecular levels. Here we report a direct assay for the tissue and temporal regulation of Ddc. A dopa decarboxylase (DDC) peptide was obtained by bacterial expression of a portion of the DDC gene in a pUC plasmid. Antisera raised against this biologically purified DDC peptide react specifically with Drosophila DDC in histological preparations and protein blots. The levels of DDC cross-reacting material closely parallel the levels of enzyme activity observed during development, indicating that DDC is degraded during periods of declining activity. We find that DDC is expressed in only two tissues, namely, the epidermis and the nervous system of the larva and adult. Epidermal DDC was found within the epidermal cells and was not detected in the overlying cuticle. DDC-containing neurons were observed in the central as well as in the visceral nervous system. Paired and unpaired midline neurons in the ventral ganglia are arranged in a segmental pattern. A subset of the DDC-positive neurons appears to correlate with the serotonin-positive neurons suggesting that the others are producing only dopamine. We find that the DDC activity associated with the proventriculus and ovary is due to the presence of DDC in the stomatogastric and caudal system neurons specifically associated with those structures.

Animals↗

Developmental consequences of awdb3, a cell-autonomous lethal mutation of Drosophila induced by hybrid dysgenesis.

In order to recover mutations affecting imaginal discs in a way which would allow the relevant genes to be readily cloned, a hybrid dysgenic screen was performed for mutations causing late larval/early pupal lethality. This paper describes that mutagenesis procedure and the phenotypes caused by the mutations that were recovered. Of 81 late larval/pupal lethal mutations that were recovered, 20 cause imaginal disc defects. These 20 mutations define 12 different genes. This paper also includes a description of the developmental defects caused by a mutation in one of those 12 genes which we have named abnormal wing discs (awd); the following paper (C. Dearolf, N. Tripoulas, J. Biggs, and A. Shearn, 1988, Dev. Biol. 129, 169-178) describes the cloning of the awd gene and an analysis of its pattern of transcription. awdb3 homozygotes develop at a normal rate until the end of the second larval instar, when their rate of development is reduced. After an extended third larval instar, they form puparia and die. Mutant wing discs have an abnormal morphology and extensive cell death. These abnormal wing discs, and also the leg and eye-antenna discs which appear to be morphologically normal, differentiate poorly or not at all when injected into metamorphosing larvae. Analysis of genetic mosaics indicates that the awdb3 mutation is expressed in a cell-autonomous manner in wing, leg, and eye-antenna discs. The larval brain and proventriculus in awdb3 homozygous third-instar larvae appear to be vacuolated due to the accumulation of lipid droplets. Mutant ovaries are unable to develop when injected into wild-type larvae, although mutant germ cells are capable of producing normal eggs.

Animals↗

Discriminative stimulus properties of cocaine. Effects of apomorphine, haloperidol, procaine and other drugs.

In pigeons trained to discriminate between the presence and absence of 3 mg/kg of cocaine, combinations of intramuscularly injected (i.m.) procaine (0.7-7.0 mg/kg) plus cocaine (0.3-3.0 mg/kg) did not alter the drug (cocaine)-dose generalization curve as compared to cocaine alone although tests with large doses of procaine given alone (30.0 and 56.0 mg/kg) engendered dose-related responding appropriate to cocaine. Apomorphine (0.56 mg/kg, i.m.) also elicited more than 50% cocaine-appropriate responding, as did doses of 10 mg/kg of intragastrically administered cocaine, given by gavage at the opening of the proventriculus; of the two treatment-test intervals (15 and 30 min) examined the generalization effect was greater at 30 min as compared to 15 min after administration. D-Lysergic acid diethylamide (0.1 mg/kg) morphine (3.0 mg/kg), pentobarbital (10.0 mg/kg), and delta 9-tetrahydrocannabinol (0.3 mg/kg) caused less than 16% pecking responses on the cocaine-appropriate key. The discriminative stimulus effects of cocaine (3.0 mg/kg) were attenuated in a dose-related manner by the neuroleptic haloperidol (dose range tested: 0.1-1.0 mg/kg). Neither the antagonism, nor the substitution tests with haloperidol were accompanied by a significant change in the percentage of responding on the initially selected position (key) by the pigeons.

Animals↗

Influence of vagotomy in domestic fowls on feeding activity, food passage, digestibility and satiety effects of two peptides.

The effects of bilateral vagotomy at the level of the proventriculus, in immature female fowls (VAG), on body weight, feeding activity parameters, rate of food passage, digestibility, and satiety effects of bombesin (BBS) and cholecystokinin octapeptide (CCK8), were compared with those in sham-operated controls (SHAM). SHAM birds gained weight at a greater rate postoperatively than before their operation, whereas VAG birds did not. Daily food intake did not change significantly as a result of the operation with either SHAM or VAG birds, and the only effect on feeding activity parameters was on the length of intermeal intervals, which increased in VAG birds. Rate of passage of the layers' mash diet was slower, and its apparent digestibility lower, in VAG than in SHAM birds. Short-term suppression of food intake, following intravenous injections of BBS (10 micrograms/kg) or CCK8 (10 micrograms/kg), did not differ between SHAM and VAG birds. The different postoperative weight gains may have been a consequence of different weights of food digested, and the difference in interval length was probably due to the different rates of food passage. The results of these experiments indicate that efferent information affecting rate of passage and digestibility travels via the vagus, but that afferent information concerned with initiation and termination of meals, and with satiety effects of BBS and CCK8, does not. Instead, such afferent information may travel via the intestinal nerve, which is unique to birds.

Animals↗

An investigation into the role of the crop in control of feeding in Japanese quail and domestic fowls.

With normal diets, removal of the crop in Japanese quail and domestic fowls caused reductions in mean meal lengths and sizes, and compensatory increases in meal frequencies, only in those (30-40%) birds that had previously eaten larger, less frequent meals. Sham operation had no such effect. Cropectomy had less effect on feeding activity parameters when quail were fed on a diluted (40% cellulose) diet, and had no effect on diurnal patterns of feeding with either undiluted or diluted food (all birds tending to eat more at the end of the day). This may have been because cropectomized birds could store food in the oesophagus in amounts similar to those previously stored in the crop. Cropectomy had no apparent long-term effect on food intake with undiluted diets, but may have suppressed it slightly with diluted food. In intact quail and fowls, with ad lib access to food when killed, crops were often found to be empty with undiluted food, but were rarely so with diluted food. Gizzards also tended to hold more with diluted food, but were never completely empty with any diet. The post-crop oesophagus and proventriculus were empty in nearly all birds. In quail fasted for two hours, then allowed to feed for 20 min and killed at intervals over a further two hours, maximum amounts of undiluted and diluted food in crops and gizzards were generally greater than in ad lib-fed quail. Crops and gizzards emptied faster with diluted than with undiluted food, but no gizzard was completely empty two hours after feeding. The results of these experiments indicate that, with normal diets, meal termination (satiety) during most of the day is associated with partial crop filling in (30-40%) birds that habitually eat larger, less frequent meals, and with varying degrees of gizzard filling in birds with smaller meals. Satiety involves more crop filling in more birds with diluted food, and this may also apply to other factors that cause increased feeding activity. Meal initiation (hunger) may be associated with partial gizzard emptying in all birds. At some stage towards the end of the day there is usually a conditioned change to cumulative filling of the crop with enough food to be processed overnight.

Animals↗

A role for the liver in the effects of glucagon on food intake in domestic fowl.

Adolescent cockerels of an egg-laying strain were prepared with catheters into the hepatic portal vein (HPV) and offered a standard poultry ration ad lib. Injection of 10, 100 and 1000 micrograms of bovine glucagon into the HPV caused a depression in intake which was significantly different from the control from 60 to 90 minutes after injection and was related to the logarithm of the dose. In birds prepared with HPV and jugular vein catheters, 1000 micrograms of glucagon had a similar depressing effect on intake irrespective of route of administration. In cockerels vagotomised at the level of the proventriculus, doses of glucagon up to 1000 micrograms injected into the HPV had no significant effect on intake. When vagotomised and sham-operated birds, in direct comparison, were injected with 0, 5 and 50 micrograms glucagon, there was s significant depression with both doses in the sham-operated cockerels but no effect in those which were vagotomised. However, the vagotomised birds had low control food intakes and the data obtained from them must be interpreted with caution. The conclusion is drawn that glucagon affects liver metabolism to influence the information transmitted via the vagus nerves to the central nervous system circuits involved in the control of feeding.

Animals↗

Food intake of domestic fowl injected with adrenergic agonists and antagonists into the hepatic portal vein.

Cockerels of an egg-laying strain were used to study the mode of action of epinephrine on food intake in chickens. Intraperitoneal injection of 2500 micrograms epinephrine significantly depressed intake from 1-6 hr after injection. This effect was not modified by vagotomy at the level of the proventriculus (equivalent of subdiaphragmatic vagotomy in the mammal). Injection of 25, 50 or 100 micrograms epinephrine into the hepatic portal vein depressed intake in a dose-related manner. One hundred micrograms epinephrine had similar effects when injected into the jugular vein as into the portal vein, although the latter injection had longer-lasting effects. As the liver is the major site of inactivation of epinephrine this suggests that it acts mainly at that organ. In order to find which type of receptor is stimulated by epinephrine in its action on feeding an alpha-adrenergic agonist, phenylephrine, was injected into the portal vein at doses ranging from 63-3000 micrograms; there was no effect on intake at any dose. A beta-adrenergic agonist, salbutamol (500-2000 micrograms), depressed intake in a dose-related manner following portal vein injection. This effect was not attenuated by vagotomy. Aminophylline, an inhibitor of cAMP breakdown, had no effect on intake when injected into the portal vein (2500-10000 micrograms) and the depressing effect of 200 micrograms epinephrine was not modified by simultaneous injection of 10000 micrograms aminophylline. It is concluded that epinephrine acts on the liver to suppress intake via a vagally-mediated pathway, but that the mechanisms of action are not known.

Albuterol↗

The effect of C-terminus and N-terminus iodination on avian pancreatic polypeptide (APP) binding to its chicken brain receptor.

In previous studies, membranes from chicken gastrointestinal tissues failed to bind appreciable levels of 125I-APP labeled at the C-terminus. In order to address the suggestion that this was due to steric hindrance of the critical C-terminus, N-terminally labeled 125I-APP was utilized in in vitro membrane binding assays. Membranes from chicken cerebellum and spleen specifically bound N-terminally iodinated APP, while those from gastrointestinal tissues including pancreas, mucosal and muscle layers of duodenum and proventriculus did not. Cerebral cortex membranes also failed to specifically bind Bolton-Hunter labeled 125I-APP. Liver membranes, which previously were shown to bind C-terminally iodinated APP with low affinity, also did not specifically bind N-terminally labeled preparations. It is concluded that the inability of membranes from gastrointestinal tissues and brain regions other than cerebellum to bind 125I-APP is not an artifact of location of iodine placement on the molecule and that both the N- and C-termini may be important for receptor binding. It is also concluded that liver APP binding sites may be structurally distinct from those in the cerebellum, and that gastrointestinal tissues may not be direct targets for APP action.

Animals↗

Xenopsin-related peptide generated in avian gastric extracts.

Two avian counterparts to amphibian xenopsin have been identified as H-Phe-His-Pro-Lys-Arg-Pro-Trp-Ile-Leu-OH (XP-2) and its partial sequence H-His-Pro-Lys-Arg-Pro-Trp-Ile-Leu-OH (XP-1) isolated from extracts of turkey proventriculus and skin. Both peptides were shown to be present within these and other tissues primarily (99%) in precursor form(s), from which they were liberated by the action of endogenous enzyme(s) during extraction. Synthetic and native preparations of XP-2 increased vascular permeability in rats and released histamine from isolated rat mast cells at submicromolar concentrations. The ubiquitous distribution of this XP-related sequence and its pharmacologic capabilities suggest potential roles in the general regulation of tissue blood flow and fluid exchange.

Amino Acid Sequence↗

The mechanism of action of gastrin releasing peptide (GRP) in stimulating avian gastric acid secretion.

The mechanisms of action of gastrin and gastrin releasing peptide (GRP) in stimulating gastric acid secretion were examined in the anaesthetized turkey. Gastrin and GRP produced dose-dependent increases in acid secretion that were inhibited by the gastrin/CCK-B antagonist CI988. The antagonist did not affect the acid secretory responses to histamine or carbachol. A GRP antagonist (M216140) inhibited the acid response to GRP, but not gastrin. The results suggest that in birds, GRP stimulates acid secretion by release of gastrin, which acts in turn on classical gastrin/CCK-B receptors in the proventriculus.

Analysis of Variance↗

Bombesin in human neuroendocrine (NE) neoplasms.

Bombesin is a 14 amino acid peptide isolated from amphibian skin which was found to have stimulatory effects upon gastric and pancreatic secretions, release of gastrointestinal hormones, gallbladder contraction and bronchoconstriction. It is present in amphibian gastric endocrine cells, avian proventriculus endocrine cells and avian brain. In mammals it is present mainly in nerve cells and fibers. The only mammalian endocrine cell shown to date to have bombesin is the P-cell in fetal lung. Bombesin is also found in mammalian brain, with its highest concentration in the hypothalamus. We examined several groups of human neuroendocrine neoplasms for the presence of bombesin by immunohistochemistry. Our findings indicate that bombesin is present 68% of bronchial carcinoids, 65% of pulmonary neuroendocrine carcinomas, 62% of neuroendocrine carcinomas of the skin, 5-10% of pheochromocytomas and extraadrenal paragangliomas and 35% of gastrointestinal carcinoids and neuroendocrine carcinomas. Parallel studies in a wide variety of non neuroendocrine neoplasms failed to reveal the presence of bombesin. We conclude that bombesin is a highly specific marker of neuroendocrine differentiation and thus a valuable tumor marker. Furthermore, its specificity compares favorably with another neuroendocrine marker, neuron specific enolase, an enzyme thought to be present only in neural tissues and neuroendocrine cells but recently found in non neural human tissues and non neuroendocrine neoplasms.

Bombesin↗

Food intake, gastric secretion, and motility as affected by avian pancreatic polypeptide administered centrally in chickens.

The effects of intracerebroventricular (ICV) injections of avian pancreatic polypeptide (APP) on food intake, gizzard motility, gastric secretion volume, pH, and pepsin concentration was investigated using 16-20-week-old Single-Comb White Leghorn hens. Birds were stereotaxically cannulated in the right lateral ventricle. In addition, a strain gauge was attached to the gizzard to measure motility and a polyethylene cannula was implanted into the caudoventral margin of the proventriculus to collect glandular secretions. All birds were fasted for 18 hr prior to the injection of APP. In Experiment 1 food was made available immediately following the injection of APP while in Experiment 2 food was withheld for an additional one hr post-injection. The ICV injection of APP significantly increased food intake but had no significant effect on gizzard motility, gastric secretion volume, pH, or pepsin concentration in birds given access to food immediately after injection. In birds which remained fasted after injection, pepsin concentration was decreased by APP injection, but gizzard motility, gastric secretion volume, and pH were not affected. Because ICV injections of APP significantly increased food intake and, in fasted birds, decreased pepsin concentration, it appears that APP is involved in the central nervous system control of food intake and pepsin secretion in the domestic fowl.

Animals↗

Tissue distribution and excretion of radioactivity following administration of 14C-labeled deoxynivalenol to White Leghorn hens.

The disposition of [14C]deoxynivalenol ([14C]DON) administered to hens as either a single oral dose or consumed in spiked feed over a 6-day period was determined by tracing the specific radioactivity of tissues and excreta. Following a single intubated dose (2.2 mg [14C]DON; 2.4 microCi/bird), the toxin was found to be poorly absorbed; peak plasma levels (2-2.5 hr post-treatment) accounted for less than 1% of the administered dose. Maximum tissue residues were measured at 3 hr in all tissues (liver, kidney, brain, heart, spleen, proventriculus, gizzard, small intestine) except for fat, muscle, and oviduct which occurred at 6 hr postdosing. Among the organs, the highest activities were measured in kidney, liver, and spleen; however, these levels were equal to less than 500 ng DON equivalents/g tissue, and declined quickly. Clearance of radioactivity from tissue had an average half-life of 16.83 +/- 8.2 hr (range 7.7-33.3 hr, depending on the tissue). Elimination of the labeled toxin in excreta occurred rapidly; recovery of radioactivity accounted for 78.6, 92.1, and 98.5% of the dose by 24, 48, and 72 hr, respectively. In continuously dosed birds fed 2.2 mg unlabeled DON for 6 days followed by 2.2 mg (1.5 microCi) [14C]DON for 6 days, accumulation of radioactivity in tissues did not occur. Maximum residual levels, which occurred in the kidneys, were only 60 ng DON equivalents/g. Estimated level of residues contained in the edible tissues amounted to only 13-16 micrograms DON/1.5 kg hen.

Animals↗

Cell membrane amino acid transport processes in the domestic fowl (Gallus domesticus).

Intestinal absorption of amino acids in the chicken occurs by way of processes which are concentrative, Na+-dependent and dependent upon metabolic energy in the form of ATP. Intestinal transport is carrier-mediated, subject to exchange transport (trans-membrane effects) and is inhibitable by sugars, reagents which inactivate sulfhydryl groups, potassium ion, and by deoxpyridoxine, an anti-vitamin B6 agent. It is stimulated by phlorizin, a potent inhibitor of sugar transport, and in Na+-leached tissue by modifiers of tissue cyclic AMP levels, e.g. theophylline, histamine, carbachol and secretin. Separate transport sites with broad, overlapping specificities function in the intestinal absorption of the various classes of common amino acids. A simple model for these sites includes one for leucine and other neutral amino acids, one for proline, beta-alanine and related imino and amino acids, one for basic amino acids, and one for acidic amino acids. Absorption of amino acids appears to be widespread in occurrence in the digestive tract of the domestic fowl; transport has been reported to be present in the crop, gizzard, proventriculus, small intestine and in the colon. By the end of the first week of life post-hatch, the caecum loses its ability to transport. Similarly, the yolk sac loses its ability by the second day post-hatch. Intestinal transport was noted before hatch and was found to be maximal immediately post-hatch. A requirement for Ca2+ appears to be lost after the first week of life post-hatch. The cationic amino acids appear to be reabsorbed by a common mechanism in the kidney. Transport rates of leucine measured in the intestine or in the erythrocyte were found to cluster about discrete values when many individual chickens were surveyed; such patterns may be an expression of gene differences between individuals. Two lines of chickens have been developed, one high and the other low uptake, through selective breeding based on the ability of individual birds to absorb leucine in erythrocytes. High leucine absorbing chickens were found to be more effective in absorbing lysine and glycine, were more effectively stimulated by Na+, had greater erythrocyte Na+, K+-ATPase activity, and their erythrocytes contained about 20% less Na+ than low line erythrocytes. The underlying genetic difference between these lines may reside at the level of the Na+, K+-ATPase and (or) with a regulatory gene determining carrier copies. Amino acid transport in erythrocytes was noted to be highest in pre-hatch chicks and to diminish during post-hatch development.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗

Ontogeny of the gastrointestinal motility in young broilers.

Gastrointestinal motility of young broilers (1, 8 and 15 days old) was measured by means of 14C-polyethylene glycol-4000. Two motor patterns can be observed: GI segments anterior to ileum increased their motility proportionally to the broiler age. GI segments below ileum decreased their motility when the broiler age is increased. It is concluded that these motor patterns are due to immaturity of gastric motility, early learning of food intake regulation and/or interference between prenatal and postnatal nutrition. Proventriculus and duodenal loop showed to be transit segments, with independence of the broiler age.

Age Factors↗

Gastric acid secretion in the chicken: effect of histamine H2 antagonists and H+/K(+)-ATPase inhibitors on gastro-intestinal pH and of sexual maturity calcium carbonate level and particle size on proventricular H+/K+ ATPase activity.

1. Cimetidine was more potent 4 hr after a single injection of 25 or 100 mg/kg body wt in increasing gastric pH than other H2 receptor antagonists, ranitidine and famotidine but was less efficient than H+/K(+)-ATPase inhibitors. Omeprazole rose proventricular and gizzard pH at a lower dose than SCH 28080 and Ro 18-5364 (30, 50 and 200 mg/kg body wt, respectively). 2. Proventricular and gizzard pH values were maximal 1 and 4 hr after a single injection of 7.5 mumol/kg body wt omeprazole. Inhibition of acid secretion was maintained for 24 hr after an injection of 100 mumol/kg. 3. H+/K(+)-ATPase activity in vitro was 10 mumol Pi/hr/mg protein in the microsomal fractions of the proventriculus. It was doubled by nigericine and inhibited by SCH 28080. However, western blots by high specific H+/K(+)-ATPase monoclonal antibody 95-A3 and 95-111 recognized a 42 kDa band but hardly exhibited the specific 95 kDa band recognition. 4. Chickens and immature pullets showed a higher H+/K(+)-ATPase activity than laying hens. Calcium level of the diet did not affect the enzyme activity but coarse particles of calcium fed to pullets or laying hens enhanced the H+/K(+)-ATPase activity when compared with ground particles.

Animals↗

Interaction between Eimeria uzura infection and aflatoxicosis in Japanese quail (Coturnix coturnix japonica).

The clinical signs and gross lesions caused by Eimeria uzura (10(5) oocysts) in Japanese quail (Coturnix coturnix japonica) exhibited little or no influence in the face of intercurrent dietary aflatoxicosis (1 p.p.m. of aflatoxin B1 from Day 0 to 55). Similarly, no significant differences in the mucosal morphology of the intestine were evident histologically between the two groups of Japanese quail. The nervous signs of ataxia, leg weakness, incoordination of movement, torticollis and terminal opisthotonos were toxin-induced manifestations. In the aflatoxic quail, hypoplastic changes and selective depletion of lymphocytes were more prominent in the bursa of fabricius. Increased relative mean weights of liver, kidney, spleen, crop, proventriculus and gizzard were observed in birds due to aflatoxin sensitivity. The combination of E. uzura infection and aflatoxicosis in Japanese quail may cause significant weight loss, and increased oocyst production and reproductive potential.

Aflatoxin B1↗

Pituitary adenylate cyclase activating peptide: a novel vasoactive intestinal peptide-like neuropeptide in the gut.

Pituitary adenylate cyclase activating peptide (PACAP) is a vasoactive intestinal peptide (VIP)-like hypothalamic peptide occurring in two forms, PACAP-27 and the C-terminally extended PACAP-38. The predicted rat and human PACAP sequence is identical to the isolated ovine one. In the present study, the occurrence and distribution of PACAP-like peptides were examined in the gut of several species by immunocytochemistry and immunochemistry using an antibody raised against PACAP-27. PACAP-like immunoreactivity was observed in nerve fibers in the gut wall of all species examined (chicken, mouse, rat, hamster, guinea-pig, ferret, cat, pig, sheep and man). In the chicken and human gut, immunoreactive fibers were numerous in all layers. In the other species examined the fibers were predominantly found in the myenteric ganglia and smooth muscle. Delicate PACAP-immunoreactive fibers were seen in the gastric mucosa of mouse, rat, hamster and man but not in the other species examined. The chicken proventriculus harbored numerous PACAP-immunoreactive endocrine cells which were identical with the serotonin-containing cells storing gastrin-releasing peptide. PACAP-immunoreactive nerve cell bodies were numerous in the submucous ganglia and moderate in number in the myenteric ganglia of the human gut. They were few in the intramural ganglia of the other species examined. Extrinsic denervation (performed on segments of rat and guinea-pig small intestine) did not visibly affect the PACAP innervation, indicating an intramural origin of most PACAP-immunoreactive fibers. Double immunostaining for VIP and PACAP revealed co-existence of the two peptides in nerve cell bodies and nerve fibers of the human and chicken gut and in fibers in the gastric mucosa of mouse and rat. In all other species examined and in all other locations in the gut PACAP-immunoreactive nerve cell bodies and nerve fibers were distinct from those storing VIP; many of them contained gastrin-releasing peptide instead. Immunochemistry revealed PACAP-like peptides in gut extracts of all species studied; upon high performance liquid chromatography the immunoreactive material co-eluted with synthetic PACAP-27. The distribution of PACAP-immunoreactive nerve cell bodies and nerve fibers in the gut wall suggests their involvement in the regulation of both motor and secretory activities.

Amino Acid Sequence↗