Mechanism and function of phasic firing in vasopressin releasing magnocellular neurosecretory cells

2021 ◽  
Author(s):  
Zahra S. Thirouin ◽  
Charles W. Bourque
Keyword(s):  
Neurosecretory Cells ◽  
And Function

scholarly journals ATP Signaling in the Integrative Neural Center of Aplysia Californica

2021 ◽  
Author(s):  
János Györi ◽  
Andrea Kohn ◽  
Daria Romanova ◽  
Leonid Moroz
Keyword(s):  
Ion Channels ◽  
Xenopus Oocytes ◽  
Aplysia Californica ◽  
P2x Receptors ◽  
Neurosecretory Cells ◽  
Early Cleavage ◽  
Signaling Systems ◽  
Purinergic Transmission ◽  
And Function ◽  
Atp Signaling

Abstract ATP and its ionotropic P2X receptors are components of the most ancient signaling systems. However, little is known about the distribution and function of purinergic transmission in invertebrates. Here, we cloned, expressed, and pharmacologically characterized P2X receptors in the sea slug Aplysia californica – the prominent neuroscience model. acP2X receptors were successfully expressed in Xenopus oocytes and were displayed activation by ATP with two-phased kinetics and Na+-dependence. Pharmacologically, they were quite different from other P2X receptors. The ATP analog, Bz-ATP, was a less effective agonist than ATP, and PPADS was a more potent inhibitor of the acP2X receptors than the suramin. acP2X were uniquely expressed within the cerebral F-cluster, which contains multiple secretory peptides (e.g., insulins, interleukins, and potential toxins), ecdysone-type receptors, and a district subset of ion channels. We view F-cluster as the multifunctional integrative center, remarkably different from other neurosecretory cells. acP2X receptors were also found in the chemosensory structures and the early cleavage stages. Therefore, in molluscs, rapid ATP-dependent signaling can be implicated both in development and diverse homeostatic functions. Furthermore, this study illuminates novel cellular and systemic features of P2X-type ligand-gated ion channels for deciphering evolution of neurotransmitters.

Localization of Merkel cells at hairless and hairy human skin sites using keratin 18

1995 ◽  
Vol 73 (9-10) ◽  
pp. 635-639 ◽  
Author(s):  
Julie Fradette ◽  
Marie-Josée Godbout ◽  
Martine Michel ◽  
Lucie Germain
Keyword(s):  
Human Skin ◽  
Basal Layer ◽  
Sensory Nerve ◽  
Neurosecretory Cells ◽  
Nerve Fibers ◽  
Hair Follicles ◽  
Merkel Cells ◽  
Merkel Cell ◽  
Skin Receptor ◽  
And Function

Merkel cells are neurosecretory cells of the skin with epithelial features such as desmosomes and expression of keratins 8, 18, 19, and 20. Merkel cells are scarcely distributed in adult human skin. Although they are present in hair follicles, their density is higher at hairless anatomic sites such as palms and soles. These cells are often innervated by sensory nerve fibers and are thought to be specialized mechanosensory skin receptor cells. However, their precise origin and function are not clearly established. The aim of this study was to localize Merkel cells in human hairless and hairy skin by immunohistochemistry with antibodies Ks18.174 and Ks19.1 directed against keratins 18 and 19, respectively. In glabrous skin of palm and sole, Merkel cells have been localized at the bottom of the rete ridges, in the epidermal basal layer. To study Merkel cell distribution at hairy anatomic sites, we have chosen breast skin, a tissue containing small hair follicles typical of those covering most of the body's surface. Merkel cells were present in the interfollicular epidermis. In hair follicles, they have been identified in the isthmus region.Key words: skin, human, Merkel cell, keratin, hair follicle.

scholarly journals Drosophila larval to pupal switch under nutrient stress requires IP3R/Ca2+ signalling in glutamatergic interneurons

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Siddharth Jayakumar ◽  
Shlesha Richhariya ◽  
O Venkateswara Reddy ◽  
Michael J Texada ◽  
Gaiti Hasan
Keyword(s):  
Calcium Imaging ◽  
Cholinergic Neurons ◽  
Neurosecretory Cells ◽  
Nutrient Stress ◽  
Ventral Ganglion ◽  
Glutamatergic Neurons ◽  
Ring Gland ◽  
Drosophila Larvae ◽  
Circuit Components ◽  
And Function

Neuronal circuits are known to integrate nutritional information, but the identity of the circuit components is not completely understood. Amino acids are a class of nutrients that are vital for the growth and function of an organism. Here, we report a neuronal circuit that allows Drosophila larvae to overcome amino acid deprivation and pupariate. We find that nutrient stress is sensed by the class IV multidendritic cholinergic neurons. Through live calcium imaging experiments, we show that these cholinergic stimuli are conveyed to glutamatergic neurons in the ventral ganglion through mAChR. We further show that IP3R-dependent calcium transients in the glutamatergic neurons convey this signal to downstream medial neurosecretory cells (mNSCs). The circuit ultimately converges at the ring gland and regulates expression of ecdysteroid biosynthetic genes. Activity in this circuit is thus likely to be an adaptation that provides a layer of regulation to help surpass nutritional stress during development.

The digestive tract of actinotroch larvae (Lophotrochozoa, Phoronida): anatomy, ultrastructure, innervations, and some observations of metamorphosis

2010 ◽  
Vol 88 (12) ◽  
pp. 1149-1168 ◽  
Author(s):  
Elena N. Temereva
Keyword(s):  
Fine Structure ◽  
Digestive Tract ◽  
Basal Lamina ◽  
Muscle Cells ◽  
Proximal Part ◽  
Neurosecretory Cells ◽  
Structure And Function ◽  
Fine Structure And Function ◽  
Phoronopsis Harmeri ◽  
And Function

The digestive tract of actinotroch consists of the vestibulum, oesophagus, stomach with stomach diverticulum, midgut, and proctodaeum. Monociliate muscle cells resting on the basal lamina of the oesophagus form its circular musculature. The epithelium of the cardiac sphincter contains axonal tracts and neurosecretory cells. Glandular, secretory, and digestive cells form the epithelium of the stomach and stomach diverticulum. The epithelium of the midgut is biciliate. The proctodaeum is divided into two parts, differing in fine structure and function. Individual serotonian and FMRFamide neurons and fibers occur in the oesophagus, cardiac sphincter, and midgut, as well as surrounding the anus. In larvae of Phoronopsis harmeri Pixell, 1912 during metamorphosis, the larval oesophagus gives rise to the juvenile oesohagus, the upper portion of the stomach stretches and transforms into prestomach, the stomach diverticulum moves into the stomach and then is digested, the larval stomach becomes the juvenile stomach, the midgut gives rise to the pyloric region, and the proctodaeum transforms into the ascending branch of the juvenile digestive tract. The data do not support the views that the proximal part of adult digestive tract forms from the ectodermal epithelium of the dorsal and ventral epidermis of the larva or that the telotroch enters the intestine during metamorphosis.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

The Effect of Oxidized Cholesterol on the Aorta of Rabbits- Scanning Electron Microscopic Observations

1982 ◽  
Vol 40 ◽  
pp. 340-341
Author(s):  
S. K. Pena ◽  
C. B. Taylor ◽  
J. Hill ◽  
J. Safarik
Keyword(s):  
Cholesterol Biosynthesis ◽  
Cholesterol Content ◽  
Arterial Injury ◽  
Electron Microscopic ◽  
Aortic Smooth Muscle ◽  
Oxidized Cholesterol ◽  
Initial Event ◽  
Membrane Structure And Function ◽  
Scanning Electron Microscopic ◽  
And Function

Introduction: Oxidized cholesterol derivatives have been demonstrated in various cell cultures to be very potent inhibitors of 3-hvdroxy-3- methylglutaryl Coenzyme A reductase which is a principle regulator of cholesterol biosynthesis in the cell. The cholesterol content in the cells exposed to oxidized cholesterol was found to be markedly decreased. In aortic smooth muscle cells, the potency of this effect was closely related to the cytotoxicity of each derivative. Furthermore, due to the similarity of their molecular structure to that of cholesterol, these oxidized cholesterol derivatives might insert themselves into the cell membrane, alter membrane structure and function and eventually cause cell death. Arterial injury has been shown to be the initial event of atherosclerosis.

Ultrastructure of developing visual cortical synapses in the cat superior colliculus

1991 ◽  
Vol 49 ◽  
pp. 156-157
Author(s):  
Caroline A. Miller ◽  
Laura L. Bruce
Keyword(s):  
Superior Colliculus ◽  
Phosphate Buffer ◽  
Receptive Fields ◽  
Visual Cortical Area ◽  
Cortical Synapses ◽  
Visual Cortical ◽  
And Function ◽  
Phosphate Buffered Saline ◽  
The Brain ◽  
Cat Superior Colliculus

The first visual cortical axons arrive in the cat superior colliculus by the time of birth. Adultlike receptive fields develop slowly over several weeks following birth. The developing cortical axons go through a sequence of changes before acquiring their adultlike morphology and function. To determine how these axons interact with neurons in the colliculus, cortico-collicular axons were labeled with biocytin (an anterograde neuronal tracer) and studied with electron microscopy.Deeply anesthetized animals received 200-500 nl injections of biocytin (Sigma; 5% in phosphate buffer) in the lateral suprasylvian visual cortical area. After a 24 hr survival time, the animals were deeply anesthetized and perfused with 0.9% phosphate buffered saline followed by fixation with a solution of 1.25% glutaraldehyde and 1.0% paraformaldehyde in 0.1M phosphate buffer. The brain was sectioned transversely on a vibratome at 50 μm. The tissue was processed immediately to visualize the biocytin.

Structural modifications of intercellular junctions.

1978 ◽  
Vol 36 (2) ◽  
pp. 330-331
Author(s):  
J. Metz ◽  
M. Merlo ◽  
W. G. Forssmann
Keyword(s):  
Gap Junctions ◽  
Intercellular Junctions ◽  
Cell Isolation ◽  
Extrahepatic Cholestasis ◽  
Structural Modifications ◽  
Pancreatic Duct Ligation ◽  
Pancreatic Cells ◽  
Duct Ligation ◽  
Thin Sectioning ◽  
And Function

Structure and function of intercellular junctions were studied under the electronmicroscope using conventional thin sectioning and freeze-etch replicas. Alterations of tight and gap junctions were analyzed 1. of exocrine pancreatic cells under cell isolation conditions and pancreatic duct ligation and 2. of hepatocytes during extrahepatic cholestasis.During the different steps of cell isolation of exocrine pancreatic cells, gradual changes of tight and gap junctions were observed. Tight junctions, which formed belt-like structures around the apex of control acinar cells in situ, subsequently diminished, became interrupted and were concentrated into macular areas (Fig. 1). Aggregations of membrane associated particles, which looked similar to gap junctions, were intermixed within tight junctional areas (Fig. 1). These structures continously disappeared in the last stages of the isolation procedure. The intercellular junctions were finally separated without destroying the integrity of the cell membrane, which was confirmed with porcion yellow, lanthanum chloride and horse radish peroxidase.

Structural similarity of ribosomes from E. coli and A. salina

1978 ◽  
Vol 36 (2) ◽  
pp. 242-243
Author(s):  
M. Boublik ◽  
R.M. Wydro ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Ribosomal Proteins ◽  
Direct Evidence ◽  
Structural Similarity ◽  
Carbon Support ◽  
Artemia Salina ◽  
Uranyl Acetate ◽  
Biological Assays ◽  
E Coli ◽  
And Function ◽  
Fine Carbon

Ribosomes are ribonucleoprotein particles necessary for processing the genetic information of mRNA into proteins. Analogy in composition and function of ribosomes from diverse species, established by biochemical and biological assays, implies their structural similarity. Direct evidence obtained by electron microscopy seems to be of increasing relevance in understanding the structure of ribosomes and the mechanism of their role in protein synthesis.The extent of the structural homology between prokaryotic and eukaryotic ribosomes has been studied on ribosomes of Escherichia coli (E.c.) and Artemia salina (A.s.). Despite the established differences in size and in the amount and proportion of ribosomal proteins and RNAs both types of ribosomes show an overall similarity. The monosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) appear in the electron micrographs as round particles with a diameter of approximately 225Å for the 70S E.c. (Fig. 1) and 260Å for the 80S A.s. monosome (Fig. 2).

The Scanning Electron Microscopic Observation of the Vestibular Sensory Epithelia

1969 ◽  
Vol 27 ◽  
pp. 40-41
Author(s):  
D.J. Lim ◽  
W.C. Lane
Keyword(s):  
Semicircular Canals ◽  
Electron Microscopic Observation ◽  
Gravitational Acceleration ◽  
Electron Microscopic ◽  
Sensory Epithelia ◽  
Scanning Electron Microscopic ◽  
Vestibular Sensory Epithelia ◽  
And Function ◽  
Sand Piles ◽  
Active Investigation

The morphology and function of the vestibular sensory organs has been extensively studied during the last decade with the advent of electron microscopy and electrophysiology. The opening of the space age also accelerated active investigation in this area, since this organ is responsible for the sensation of balance and of linear, angular and gravitational acceleration.The vestibular sense organs are formed by the saccule, utricle and three ampullae of the semicircular canals. The maculae (sacculi and utriculi) have otolithic membranes on the top of the sensory epithelia. The otolithic membrane is formed by a layer of thick gelatin and sand-piles of calcium carbonate crystals (Fig.l).

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