The uropygiols: identification of the unsaponifiable constituent of a diester wax from chicken preen glands.
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The chief lipid fraction in the uropygial gland excretion of the domestic hen is a diester wax. The saponifiable fraction of this wax consists of saturated normal C(10)-C(20) fatty acids. The unsaponifiable fraction consists of a series of three homologous compounds, which have been named the uropygiols and identified by mass spectrometry, gas-liquid chromatography, and periodate cleavage as 2,3-n-alkanediols containing 22-24 carbon atoms. The native diols were shown to consist of about equal amounts of the threo and erythro isomers. Records of analyses of the natural products as well as related synthetic compounds are shown. (+info)
Glandular areas associated with the male genitalia in Triatoma rubrofasciata (Triatominae, Reduviidae, Hemiptera) and other Reduviidae.
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In this paper, glandular areas associated with the phallus in Triatoma rubrofasciata are described and illustrated for the first time. The glandular areas lie in the membrane surrounding the articulatory apparatus. In order to unambiguously define the locality of the respective glandular areas, some features of the pygophore-phallus connection are redescribed. A possible functional context of the gland secretions is discussed. A preliminary study of several other Reduviidae implies that the described glandular areas occur in a wider range of taxa in this group. (+info)
A general role for Rab27a in secretory cells.
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Vesicular transport is a complex multistep process regulated by distinct Rab GTPases. Here, we show for the first time that an EGFP-Rab fusion protein is fully functional in a mammalian organism. We constructed a PAC-based transgenic mouse, which expresses EGFP-Rab27a under the control of endogenous Rab27a promoter. The EGFP-Rab27a transgene was fully functional and rescued the two major defects of the ashen Rab27a knockout mouse. We achieved cell-specific expression of EGFP-Rab27a, which faithfully followed the pattern of expression of endogenous Rab27a. We found that Rab27a is expressed in an exceptionally broad range of specialized secretory cells, including exocrine (particularly in mucin- and zymogen-secreting cells), endocrine, ovarian, and hematopoietic cells, most of which undergo regulated exocytosis. We suggest that Rab27a acts in concert with Rab3 proteins in most regulated secretory events. The present strategy represents one way in which the complex pattern of expression and function of proteins involved in specialized cell types may be unraveled. (+info)
Stimulation of the alpha-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca.
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The noradrenergic innervation of Bothrops jararaca venom gland is thought to be important in the production and secretion of venom. We investigated the characteristics of the alpha-adrenoceptor in the venom gland and its role in venom production. This receptor had relatively low sensitivity to noradrenaline (pD(2)=4.77+/-0.09, N=7) and to phenylephrine (pD(2)=3.77+/-0.06, N=11). The receptor became desensitized just after venom extraction (pD(2) to phenylephrine fell to 3.27+/-0.02, N=6) and the sensitivity remained low for at least 15 days, returning to normal 30 days after venom extraction, by which time the snake was ready for a new cycle of venom production. Incubation of secretory cells with noradrenaline (10(-4) mol l(-1) for 5 min) reduced alpha-adrenoceptor sensitivity to the level seen after venom extraction. Blockade of catecholamine production with reserpine abolished the enlargement of the rough endoplasmic reticulum and the activation of the Golgi apparatus that are normally seen after venom extraction, and the venom production was restored by a single subcutaneous (s.c.) injection of phenylephrine (100 mg kg(-1)) immediately after venom extraction. Our data suggest that stimulation of the alpha-adrenoceptor during or shortly after biting is essential for the onset of the venom production cycle. (+info)
Mechanisms and significance of reduced activity and responsiveness in resting frog tadpoles.
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Hatchling Xenopus laevis tadpoles spend most of their time attached to objects or the water surface by mucus secreted by a gland on the head. While attached, swimming activity and responsiveness to swim-initiating stimuli are reduced over long periods of time. We have investigated the mechanisms and significance of this apparent long-term inhibition. In behavioural experiments we show, firstly, that innervation of the cement gland and GABA(A)-mediated inhibition are necessary for attachment to reduce responsiveness, and secondly, that denervation of the cement gland increases tadpole activity and increases their predation by damselfly nymphs (Zygoptera). To investigate the neuronal pathway from the cement gland to GABA(A) inhibition, we have devised an immobilized, inverted tadpole preparation where a weight attached to the mucus simulates the force as it hangs. Simulated attachment reduces responsiveness and spontaneous fictive swimming activity. We have recorded the activity and responses of trigeminal neurons innervating the cement gland. They are spontaneously active and simulating attachment results in a sustained increase in this activity. We propose that hanging from a mucus strand increases firing in cement gland afferents. This leads to tonic GABA inhibition that reduces tadpole activity and responses, and leads to fewer attacks by predators. (+info)
Overexpression of broad: a new insight into its role in the Drosophila prothoracic gland cells.
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Insect molting is triggered by ecdysteroids, which are produced in the prothoracic glands (PG). The broad (br) gene is one of the 'early genes' directly regulated by ecdysteroids. Ectopic expression of the BR-Z3 isoform in early second instar Drosophila larvae (L2) before the rise of the ecdysteroid titer prevented molting to the third instar, but the larvae subsequently formed L2 prepupae after prolonged feeding. When these larvae were fed on diet containing 20-hydroxyecdysone (20E), they formed pharate third instar larvae. The critical weight for normal L3 pupariation of w(1118) larvae was found to be 0.8 mg and that for L2 pupariation was 0.45 mg. We also defined a threshold weight for metamorphosis of 0.3 mg, above which L2 larvae will metamorphose when provided with 20E. BR-Z3 apparently works through the PG cells of the ring gland but not the putative neurosecretory cells that drive ecdysone secretion, because ectopic expression of BR-Z3 specifically in the ring gland caused 53% of the larvae to become permanent first instar larvae. Driving other BR isoforms in the ring gland prevented larval molting or pupariation to varying degrees. These molting defects were rescued by feeding 20E. Overexpression of each of the BR isoforms caused degeneration of the PG cells but on different time courses, indicating that BR is a signal for the degeneration of the PG cells that normally occurs during the pupal-adult transition. (+info)
A small molecule CFTR inhibitor produces cystic fibrosis-like submucosal gland fluid secretions in normal airways.
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Airway submucosal glands have been proposed as a primary site for initiating and sustaining airway disease in cystic fibrosis (CF). However, it has been difficult to define the role of CFTR in gland fluid secretion because of concerns in interpreting experiments on diseased CF human airways subjected to chronic infection and inflammation. Here, we test the role of CFTR in gland fluid secretion by using a selective CFTR inhibitor (CFTRinh-172) in pig and human airways. Measurements of single-gland fluid secretion rates showed inhibition of both cholinergic and cAMP-stimulated fluid secretion by CFTRinh-172. Secreted fluid [Na+] and [Cl-] measured by fluorescence ratio imaging were 101 and 116 mM, respectively, and not significantly altered by secretory agonists or CFTR inhibition. Gland fluid pH was 7.1 and reduced by 0.4 units after CFTR inhibition. Gland fluid viscosity, determined by photobleaching of FITC-dextran, was threefold increased in pilocarpine-stimulated gland fluid after CFTR inhibition, and protein concentration was increased from 12 to 20 mg/ml. Our data provide strong evidence that gland fluid secretion is CFTR-dependent. The relatively hyper-viscous and acidic fluid secretions produced by acute CFTR inhibition support a role for defective gland function in CF lung disease and provide a rational basis for pharmacological creation of a large animal model of CF. (+info)
Mist1 is necessary for the establishment of granule organization in serous exocrine cells of the gastrointestinal tract.
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Establishing a pool of granules at the luminal border is a key step during exocrine cell development in the pancreas and is necessary for efficient release of digestive enzymes through regulated exocytosis. Several proteins have been linked to maintaining granule organization, but it is unclear which regulatory mechanisms are necessary to establish organization. Based on temporal and spatial expression, the transcription factor Mist1 is an excellent candidate, and analysis of mice that do not express Mist1 (Mist1KO) reveal disrupted cell morphology in adult pancreatic acini. To address Mist1's role in establishing granule location, we have characterized the organization of pancreatic acini throughout development in Mist1KO mice. Using various histological approaches, we have determined that correct granule organization is never established in pancreatic acini of Mist1KO mice. Further examination indicates that this disruption in granule targeting may be the primary defect in Mist1KO mice as granule organization is affected in other serous exocrine cells that normally express Mist1. To identify a mechanistic link between granule targeting and the loss of Mist1 function, intercellular junctions and the expression of Rab3D were assessed. While both of these factors are affected in Mist1KO mice, these changes alone do not account for the disorganization observed in Mist1KO tissues. Therefore, we conclude that Mist1 is necessary for complete differentiation and maturation of serous exocrine cells through the combined regulation of several exocrine specific genes. (+info)