scholarly journals The fine structure of a rectifying electrotonic synapse.

1978 ◽  
Vol 79 (3) ◽  
pp. 764-773 ◽  
Author(s):  
R B Hanna ◽  
J S Keeter ◽  
G D Pappas
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Ventral Nerve Cord ◽  
Procambarus Clarkii ◽  
Giant Axon ◽  
Morphological Evidence ◽  
Giant Fiber ◽  
Ordered Array ◽  
20 Nm ◽  
Tubular Endoplasmic Reticulum

The synapses between the lateral giant axon and the giant motor axon found in the abdominal ganglia of the ventral nerve cord of the crayfish Procambarus clarkii are electronic. The junctional membrane rectifies, favoring impulse transmission from lateral giant fiber to giant motor fiber. This rectifying electronic junction consists of closely apposed membranes indistinguishable from ordinary arthropod gap junctions. The apposed membranes contain intramembrane particles that are approximately 12.5 nm in width. These particles have a central depression and are arranged in a loosely ordered array with a center-to-center spacing of about 20 nm. The only obvious morphological evidence of asymmetry is the presence of vesicles (about 80 nm in diameter) in the cytoplasm adjacent to the junctional region of the presynaptic lateral giant fiber. Vesicles are not present in the adjacent cytoplasm of the postsynaptic giant motor fiber; however, mitochondria and smooth tubular endoplasmic reticulum are more frequent in the cytoplasm of the giant motor fiber.

scholarly journals Some Observations on the Fine Structure of the Giant Nerve Fibers of the Earthworm, Eisenia foetida

1959 ◽  
Vol 6 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Kiyoshi Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Schwann Cell ◽  
Plasma Membranes ◽  
Giant Axon ◽  
Nerve Fibers ◽  
Eisenia Foetida ◽  
Tubular Structures ◽  
Giant Fiber ◽  
Nerve Sheath

Sectioned dorsal giant fibers of the earthworm Eisenia foetida have been studied with the electron microscope. The giant axon is surrounded by a Schwannian sheath in which the lamellae are arranged spirally. They can be traced from the outer surface of the Schwann cell to the axon-Schwann membranes. Irregularities in the spiral arrangement are frequently observed. Desmosome-like attachment areas occur on the giant fiber nerve sheath. These structures appear to be arranged bilaterally in columns which are oriented slightly obliquely to the long axis of the giant fiber and aligned linearly from the axon to the periphery of the sheath. At these sites they bind together apposing portions of Schwann cell membrane comprising the sheath. Longitudinal or oblique sections of the nerve sheath attachment areas are reminiscent of the Schmidt-Lantermann clefts of vertebrate peripheral nerve. Septa of the giant fibers have been examined. They are symmetrical or non-polarized and consist of the two plasma membranes of adjacent nerve units. Characteristic vesicular and tubular structures are associated with both cytoplasmic surfaces of these septa.

scholarly journals STUDIES ON FINE STRUCTURE AND CYTOCHEMICAL PROPERTIES OF ERYTHROPHORES IN SWORDTAIL, XIPHOPHORUS HELLERI, WITH SPECIAL REFERENCE TO THEIR PIGMENT GRANULES (PTERINOSOMES)

1965 ◽  
Vol 27 (3) ◽  
pp. 493-504 ◽  
Author(s):  
Jiro Matsumoto
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Special Reference ◽  
Water Soluble ◽  
Xiphophorus Helleri ◽  
Swordtail Fish ◽  
Pigment Granules ◽  
Pteridine Derivatives ◽  
Tubular Endoplasmic Reticulum

The fine structure and the composition of pteridine pigments of erythrophores in adults of the swordtail fish, Xiphophorus helleri, were studied by means of cytochemistry, paper chromatography, ionophoresis, centrifugal fractionation, and electron microscopy. It was found that water-soluble pigments of erythrophores consisted exclusively of pteridine derivatives including large amounts of drosopterin, isodrosopterin, neodrosopterin, and moderate amounts of sepiapterin. While these substances were responsible for red pigmentation, moderate quantities of colorless pteridines, biopterin, Rana-chrome 3, xanthopterin, isoxanthopterin, and others, were also detectable. The ultrastructure of the erythrophore is characterized by numerous pigment granules and a well developed tubular endoplasmic reticulum. The former consist of a three-layered limiting membrane and inner lamellae which appear to be whorl-like due to a concentric arrangement of parallel membranes. All of the mentioned pteridines are primarily contained in this organelle which is designated, accordingly, "pterinosome." The possible functions of erythrophores and pterinosomes are discussed in the light of their structure and pigmentary constitution.

Branchial water- and blood-flow patterns and the structure of the gill of the crayfish Procambarus clarkii

1974 ◽  
Vol 52 (12) ◽  
pp. 1511-1518 ◽  
Author(s):  
W. W. Burggren ◽  
B. R. McMahon ◽  
J. W. Costerton
Keyword(s):  
Blood Flow ◽  
Fine Structure ◽  
Gas Exchange ◽  
Procambarus Clarkii ◽  
Gill Filament ◽  
Morphological Evidence ◽  
Gill Epithelium ◽  
Diffusion Distance ◽  
Gill Filaments ◽  
Blood Flow Patterns

Water flow within the branchial chamber, blood flow within the gill filaments, and the fine structure of the gill epithelium have been determined in the crayfish Procambarus clarkii. The epithelium of the podobranch filaments, which is 3.15–8.70 μ thick, represents the blood-to-water diffusion distance. Blood flow within the filament is arranged in a bidirectional system that is first cocurrent and then countercurrent to the flow of water irrigating the gills. Morphological evidence suggests that gas exchange might occur in both directions. Shunting of blood occurs within the gill filament and its significance in countercurrent blood flow and gas exchange is discussed.

Fine Structure of Planarian Neuroglial Cell

1976 ◽  
Vol 34 ◽  
pp. 188-189 ◽  
Author(s):  
Michio Morita ◽  
Jay Boyd Best
Keyword(s):  
Endoplasmic Reticulum ◽  
Ventral Nerve Cord ◽  
Osmium Tetroxide ◽  
Golgi Body ◽  
Nerve Fibers ◽  
Neuroglial Cell ◽  
Glutaraldehyde Solution ◽  
Deep Indentation ◽  
Cytoplasmic Processes ◽  
Longitudinal Nerve

The species of the planarian Dugesia dorotocephala was used as the experimental animal to study a neuroglial cell in the ventral nerve cord. Animals were fixed with 3% buffered glutaraldehyde solution and postfixed with 1% buffered osmium tetroxide.The neuroglial cell is multipolar, expanding into three or four cytoplasmic processes with many daughter branches. Some neuroglial processes are found to extend perpendicular to the longitudinal nerve fibers, whereas others are seen to be parallel to them. The nucleus of the neuroglial cell is irregular in shape and frequently has a deep indentation. Convex portions of the nucleus seem to be related to the areas from which cytoplasmic processes are extended. Granular endoplasmic reticulum (Fig. 4), Golgi body (Fig. 2), mitochondria (Figs. 1 and 2), microtubules (Fig. 4), and many glycogen granules are observable in the electron dense neuroglial cytoplasm. Neuroglial cells are also observed to contain various sizes of phagosomes and lipids (Fig. 2).

The Lateral Giant Fiber to Motor Giant Fiber Synapse in Crayfish

1972 ◽  
Vol 30 ◽  
pp. 170-171
Author(s):  
Charles A. Stirling
Keyword(s):  
Synaptic Vesicles ◽  
Procambarus Clarkii ◽  
Synaptic Contact ◽  
Giant Fiber ◽  
Synaptic Junctions

The lateral giant (LG) to motor giant (MoG) synapses in crayfish (Procambarus clarkii) abdominal ganglia are the classic electrotonic synapses. They have previously been described as having synaptic vesicles and as having them on both the pre- and postsynaptic sides of symmetrical synaptic junctions. This positioning of vesicles would make these very atypical synapses, but in the present work on the crayfish Astacus pallipes the motor giant has never been found to contain any type of vesicle at its synapses with the lateral giant fiber.The lateral to motor giant fiber synapses all occur on short branches off the main giant fibers. Closely associated with these giant fiber synapses are two small presynaptic nerves which make synaptic contact with both of the giant fibers and with their small branches.

scholarly journals STED and parallelized RESOLFT optical nanoscopy of the tubular endoplasmic reticulum and its mitochondrial contacts in neuronal cells

2021 ◽  
Vol 155 ◽  
pp. 105361
Author(s):  
Martina Damenti ◽  
Giovanna Coceano ◽  
Francesca Pennacchietti ◽  
Andreas Bodén ◽  
Ilaria Testa
Keyword(s):  
Endoplasmic Reticulum ◽  
Neuronal Cells ◽  
Tubular Endoplasmic Reticulum

Cloning and characterization of an electrogenic Na/HCO3− cotransporter from the squid giant fiber lobe

2007 ◽  
Vol 292 (6) ◽  
pp. C2032-C2045 ◽  
Author(s):  
Peter M. Piermarini ◽  
Inyeong Choi ◽  
Walter F. Boron
Keyword(s):  
Giant Axon ◽  
Predicted Amino Acid Sequence ◽  
Giant Fiber ◽  
Reading Frame ◽  
Excitable Membranes ◽  
Current Voltage ◽  
Partial Cdna ◽  
Partial Cdna Clone ◽  
Current Voltage Relationship

The squid giant axon is a classic model system for understanding both excitable membranes and ion transport. To date, a Na+-driven Cl-HCO3− exchanger, sqNDCBE—related to the SLC4 superfamily and cloned from giant fiber lobe cDNA—is the only HCO3−-transporting protein cloned and characterized from a squid. The goal of our study was to clone and characterize another SLC4-like cDNA. We used degenerate PCR to obtain a partial cDNA clone (squid fiber clone 3, SF3), which we extended in both the 5′ and 3′ directions to obtain the full-length open-reading frame. The predicted amino-acid sequence of SF3 is similar to sqNDCBE, and a phylogenetic analysis of the membrane domains indicates that SF3 clusters with electroneutral Na+-coupled SLC4 transporters. However, when we measure pHi and membrane potential—or use two-electrode voltage clamping to measure currents—on Xenopus oocytes expressing SF3, the oocytes exhibit the characteristics of an electrogenic Na/HCO3− cotransporter, NBCe. That is, exposure to extracellular CO2/HCO3− not only causes a fall in pHi, followed by a robust recovery, but also causes a rapid hyperpolarization. The current-voltage relationship is also characteristic of an electrogenic NBC. The pHi recovery and current require HCO3− and Na+, and are blocked by DIDS. Furthermore, neither K+ nor Li+ can fully replace Na+ in supporting the pHi recovery. Extracellular Cl− is not necessary for the transporter to operate. Therefore, SF3 is an NBCe, representing the first NBCe characterized from an invertebrate.

Cloning and characterization of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) from crayfish axial muscle. Sarco/Endoplasmic Reticulum Ca(2+)-ATPase

2000 ◽  
Vol 203 (22) ◽  
pp. 3411-3423 ◽  
Author(s):  
Z. Zhang ◽  
D. Chen ◽  
M.G. Wheatly
Keyword(s):  
Endoplasmic Reticulum ◽  
Amino Acid ◽  
Procambarus Clarkii ◽  
Muscle Growth ◽  
Abdominal Muscle ◽  
Northern Analysis ◽  
Specific Expression ◽  
Loop Region ◽  
Moulting Cycle

The discontinuous pattern of muscle growth during the moulting cycle of a freshwater crustacean (the crayfish Procambarus clarkii) was used as a model system to examine the regulation of the expression of Sarco/Endoplasmic Reticulum Ca(2+)-ATPase (SERCA). We describe the cloning, sequencing and characterization of a novel SERCA cDNA (3856 bp) obtained from crayfish axial abdominal muscle by reverse transcription/polymerase chain reaction (RT-PCR) followed by rapid amplification of cDNA ends (RACE). This complete sequence contains a 145 base pair (bp) noncoding region at the 5′ end, a 3006 bp open reading frame coding for 1002 amino acid residues with a molecular mass of 110 kDa and 705 bp of untranslated region at the 3′ end. This enzyme contains all the conserved domains found in ‘P’-type ATPases, and the hydropathy profile suggests a transmembrane organization typical of other SERCAs. It exhibits 80% amino acid identity with Drosophila melanogaster SERCA, 79% identity with Artemia franciscana SERCA, 72% identity with rabbit fast-twitch muscle neonatal isoform SERCA1b, 71% identity with slow-twitch muscle isoform SERCA2 and 67% identity with SERCA3. Sequence alignment revealed that regions anchoring the cytoplasmic domain in the membrane were highly conserved and that most differences were in the NH(2) terminus, the central loop region and the COOH terminus. Northern analysis of total RNA from crayfish tissues probed with the 460 bp fragment initially isolated showed four bands (7.6, 7.0, 5.8 and 4.5 kilobases) displaying tissue-specific expression. SERCA was most abundant in muscle (axial abdominal, cardiac and stomach), where it is involved in Ca(2+) resequestration during relaxation, and in eggs, where it may be implicated in early embryogenesis. The level of SERCA mRNA expression in axial abdominal muscle varied during the moulting cycle as determined by slot-blot analysis. SERCA expression was greatest during intermoult and decreased to approximately 50% of this level during pre- and postmoult. Patterns of gene expression for SERCA and other sarcomeric proteins during the crustacean moulting cycle may be regulated by ecdysteroids and/or mechanical stimulation.

scholarly journals Association of the Yeast RNA-binding Protein She2p with the Tubular Endoplasmic Reticulum Depends on Membrane Curvature

2013 ◽  
Vol 288 (45) ◽  
pp. 32384-32393 ◽  
Author(s):  
Christian Genz ◽  
Julia Fundakowski ◽  
Orit Hermesh ◽  
Maria Schmid ◽  
Ralf-Peter Jansen
Keyword(s):  
Endoplasmic Reticulum ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Membrane Curvature ◽  
Tubular Endoplasmic Reticulum

scholarly journals Modeling of axonal endoplasmic reticulum network by spastic paraplegia proteins

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Belgin Yalçın ◽  
Lu Zhao ◽  
Martin Stofanko ◽  
Niamh C O'Sullivan ◽  
Zi Han Kang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hereditary Spastic Paraplegia ◽  
Membrane Curvature ◽  
Degenerative Disease ◽  
Ultrastructural Analysis ◽  
Motor Axons ◽  
Spastic Paraplegia ◽  
Partial Loss ◽  
And Function ◽  
Tubular Endoplasmic Reticulum

Axons contain a smooth tubular endoplasmic reticulum (ER) network that is thought to be continuous with ER throughout the neuron; the mechanisms that form this axonal network are unknown. Mutations affecting reticulon or REEP proteins, with intramembrane hairpin domains that model ER membranes, cause an axon degenerative disease, hereditary spastic paraplegia (HSP). We show that Drosophila axons have a dynamic axonal ER network, which these proteins help to model. Loss of HSP hairpin proteins causes ER sheet expansion, partial loss of ER from distal motor axons, and occasional discontinuities in axonal ER. Ultrastructural analysis reveals an extensive ER network in axons, which shows larger and fewer tubules in larvae that lack reticulon and REEP proteins, consistent with loss of membrane curvature. Therefore HSP hairpin-containing proteins are required for shaping and continuity of axonal ER, thus suggesting roles for ER modeling in axon maintenance and function.

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