scholarly journals Submicroscopic Changes in Visual Cells of the Rabbit Induced by Iodoacetate

1959 ◽  
Vol 5 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Arnaldo Lasansky ◽  
Eduardo De Robertis
Keyword(s):  
Body Weight ◽  
Synaptic Vesicles ◽  
Single Injection ◽  
Synaptic Membrane ◽  
Visual Cells ◽  
Rod Cells ◽  
Complete Destruction ◽  
Cone Cells ◽  
The Matrix ◽  
Myelin Figures

Alterations produced by iodoacetate in visual cells have been studied under the electron microscope. Lesions of the outer segments of the rods are visible as early as 3 hours after a single injection of 20 mg. iodoacetate per kg. body weight. After 6 hours the changes are more marked and consist then of disorganization, vesiculation, and lysis of the rod sacs. The inner segments of most rod cells show swelling and vacuolization of the matrix, the endoplasmic reticulum, and the Golgi complex. The mitochondria of the ellipsoid show a tendency to disintegrate. In some inner segments the changes consist primarily in an increase in density of the matrix and deposition of a granular material. The rod synapses are also affected, showing lysis of the synaptic vesicles and alterations of the synaptic membrane. With a second injection of 20 mg. iodoacetate per kg. body weight, all these changes become more marked and lead to complete destruction of the rod cells. The cones seem more resistant than the rods. A single injection produces no visible changes in the outer or inner segments of the cones. At cone synapses, however, there are changes consisting of fusion of synaptic vesicles and other membranous material to form large concentric membranes characteristic of myelin figures. A second dose of the drug causes complete destruction of the cone cells. All these, and other submicroscopic changes, are discussed in relation to various hypotheses put forward to explain the mode of action of iodoacetate on visual cells. The pronounced alterations of submicroscopic intracellular membranes suggest that the locus of action of iodoacetate may be a component widely dispersed throughout the visual cells and related, in some way, to the maintenance of these lipoprotein structures.

scholarly journals ELECTRON MICROSCOPE OBSERVATIONS ON SYNAPTIC VESICLES IN SYNAPSES OF THE RETINAL RODS AND CONES

1956 ◽  
Vol 2 (3) ◽  
pp. 307-318 ◽  
Author(s):  
Eduardo De Robertis ◽  
Carlos M. Franchi
Keyword(s):  
Electron Microscope ◽  
Synaptic Vesicles ◽  
Sharp Decrease ◽  
Albino Rabbit ◽  
Synaptic Membrane ◽  
Complete Darkness ◽  
Rods And Cones ◽  
Retinal Rods ◽  
Filamentous Material ◽  
Rod Cell

The submicroscopic organization of the rod and cone synapses of the albino rabbit has been investigated with the use of the electron microscope. The most common rod synapse consists of an enlarged expansion of the rod fiber (the so called spherule) into which the dendritic postsynaptic fiber of the bipolar cell penetrates and digitates. The membrane surrounding the terminal consists of a double layer, the external of which is interpreted as belonging to the intervening glial cells. The synaptic membrane has a pre- and a postsynaptic layer with a total thickness of 180 to 300 A. The presynaptic layer is frequently denser and is intimately associated with the adjacent synaptic vesicles. The synaptic membrane shows processes constituted by foldings of the presynaptic layer. The entire spherule is filled with synaptic vesicles varying in diameter between 200 and 650 A with a mean of 386 A. In addition, the spherule contains a few large vacuoles near the rod fiber, interpreted as endoplasmic reticulum, and a matrix in which with high resolution a fine filamentous material can be observed. The postsynaptic fiber is homogeneous and usually does not show synaptic vesicles. In animals maintained in complete darkness for 24 hours vesicles appear to accumulate near the synaptic membrane and its processes. After 9 days there is a sharp decrease in size of the synaptic vesicles. A special rod synapse in which the dendritic postsynaptic expansion penetrates directly into the rod cell body has been identified. In line with Cajal's classification this type of synapse could be considered as a somatodendritic one. The cone synapse has a much larger terminal with a more complex relationship with the postsynaptic fiber. However, the same components recognized in the rod synapse can be observed. In animals maintained for 9 days in complete darkness there is also a considerable diminution in size of the synaptic vesicles.

The Question of Relationship Between Golgi Vesicles and Synaptic Vesicles in Octopus Neurons

1970 ◽  
Vol 7 (1) ◽  
pp. 189-201
Author(s):  
E. G. GRAY
Keyword(s):  
Electron Microscopy ◽  
Golgi Apparatus ◽  
Frontal Lobe ◽  
Synaptic Vesicles ◽  
Optic Lobe ◽  
Visual Cell ◽  
Visual Cells ◽  
Golgi Vesicles

Electron microscopy of the vertical lobe of octopus brain shows that the synaptic knobs of axons with perikarya in the median superior frontal lobe have synaptic vesicles, approximately 28% of which are dense-cored (or granulated). In contrast, the endings of the amacrine neurons in the vertical lobe and the endings in the retina and optic lobe, both of which are derived from the retinal visual cells, have only agranular synaptic vesicles. The Golgi apparatuses of the median superior frontal perikarya have vesicles, approximately 4.3% of which are granulated. The amacrine Golgi apparatuses have 1.5% granulated vesicles. The visual cell Golgi apparatuses have virtually no dense-cored vesicles, only agranular ones. The question of the formation of dense-cored and agranular synaptic vesicles at the Golgi apparatus and their subsequent transport to the terminals are related to these observations.

Effect of epidermal growth factor on glucosamine-6-phosphate synthetase activity in the colon of neonatal mice

1985 ◽  
Vol 105 (2) ◽  
pp. 197-200 ◽  
Author(s):  
M. Hiramatsu ◽  
M. Kashimata ◽  
N. Minami ◽  
N. Minami ◽  
M. Kumegawa
Keyword(s):  
Body Weight ◽  
Enzyme Activity ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Colonic Mucosa ◽  
Single Injection ◽  
Synthetase Activity ◽  
Apparent Effect ◽  
Neonatal Mice ◽  
Epidermal Growth

ABSTRACT Epidermal growth factor (EGF), administered subcutaneously to neonatal mice at daily doses of 1, 2 and 4 μg/g body weight for 3 days, significantly increased glucosamine-6-phosphate synthetase activity in the colon. A single injection of EGF at doses of 2 and 4 μg/g body weight also significantly increased enzyme activity. When administered to mature mice, EGF (4 μg/g body weight for 3 days) had no apparent effect on the enzyme activity. From these results, we suggest that EGF acts as a trophic factor for the maturation of the colonic mucosa of neonatal mice. J. Endocr. (1985) 105, 197–200

HUMAN FIBRINOLYSIN WITH AND WITHOUT UROKINASE: ITS EFFECT ON EXPERIMENTAL ARTERIAL THROMBI IN DOGS

1962 ◽  
Vol 40 (12) ◽  
pp. 1819-1838 ◽  
Author(s):  
Walter H. E. Roschlau ◽  
Robert H. Painter
Keyword(s):  
Body Weight ◽  
Therapeutic Dose ◽  
Traditional Method ◽  
Fibrinolytic Activity ◽  
Single Injection ◽  
Clot Lysis ◽  
Undesirable Side Effect ◽  
Department Of Health ◽  
Heat Treated

The lytic effects of heat-treated, sterile solutions of spontaneously activated and urokinase-activated fibrinolysin on occlusive experimental arterial clots have been studied. For this purpose methods for the preparation of urokinase and activation of profibrinolysin, the production of traumatic arterial thrombi in dogs, and the recording of clot lysis are described. Single injection as a means of administration was compared with the traditional method of infusion. When used in conjunction with a prompt assay of the in vivo fibrinolytic activity, which was developed for this purpose, the injection method was preferred. The results indicated that spontaneous fibrinolysin, given by single injection, was as effective in lysing clots as were preparations of fibrinolysin that contained activator. The approximate therapeutic dose for both types of fibrinolysin under the conditions described was found to be 225–325 Michigan Department of Health caseinolytic units per kg body weight. Lysis of occluding arterial thrombi was achieved within a few hours after administration of fibrinolysin by injection, and arteries remained patent during the week of posttreatment observation. No toxic effects due to the fibrinolysin or the glycerol present as stabilizer could be demonstrated after the therapeutic dose. The only undesirable side effect of overdose of fibrinolysin was a transient incoagulability of the blood.

Neurotransmitter Release

2017 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicle ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Synaptic Cleft ◽  
Fusion Pore ◽  
Synaptic Membrane ◽  
Specialized Region ◽  
Synaptic Vesicle Fusion

The biochemical and physiological processes of neurotransmitter release from an active zone, a specialized region of synaptic membrane, are examined. Synaptic vesicles containing neurotransmitters are docked at the active zone and then primed for release by SNARE complexes that bring them into extreme proximity to the plasma membrane. Entry of calcium ions through voltage-gated calcium channels triggers synaptic vesicle fusion with the synaptic terminal membrane and the consequent diffusion of neurotransmitter into the synaptic cleft. Release results when the fusion pore bridging the synaptic vesicle and plasma membrane widens and neurotransmitter from the inside of the synaptic vesicle diffuses into the synaptic cleft. Membrane from the active zone membrane is endocytosed, and synaptic vesicle proteins are then reassembled into recycled synaptic vesicles, allowing for more rounds of neurotransmitter release.

scholarly journals Visual adaptation of opsin genes to the aquatic environment in sea snakes

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Takashi Seiko ◽  
Takushi Kishida ◽  
Mina Toyama ◽  
Takahiko Hariyama ◽  
Takashi Okitsu ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Photoreceptor Cell ◽  
Open Water ◽  
Visual Adaptation ◽  
Aquatic Life ◽  
Evolutionary Transitions ◽  
Sea Snakes ◽  
Rod Cells ◽  
Cone Cells ◽  
Opsin Genes

Abstract Background Evolutionary transitions from terrestrial to aquatic life history cause drastic changes in sensory systems. Indeed, the drastic changes in vision have been reported in many aquatic amniotes, convergently. Recently, the opsin genes of the full-aquatic sea snakes have been reported. However, those of the amphibious sea snakes have not been examined in detail. Results Here, we investigated opsin genes and visual pigments of sea snakes. We determined the sequences of SWS1, LWS, and RH1 genes from one terrestrial, three amphibious and four fully-aquatic elapids. Amino acid replacements at four and one spectra-tuning positions were found in LWS and RH1, respectively. We measured or predicted absorption of LWS and RH1 pigments with A1-derived retinal. During their evolution, blue shifts of LWS pigments have occurred stepwise in amphibious sea snakes and convergently in both amphibious and fully-aquatic species. Conclusions Blue shifted LWS pigments may have adapted to deep water or open water environments dominated by blue light. The evolution of opsins differs between marine mammals (cetaceans and pinnipeds) and sea snakes in two fundamental ways: (1) pseudogenization of opsins in marine mammals; and (2) large blue shifts of LWS pigments in sea snakes. It may be possible to explain these two differences at the level of photoreceptor cell composition given that cone and rod cells both exist in mammals whereas only cone cells exist in fully-aquatic sea snakes. We hypothesize that the differences in photoreceptor cell compositions may have differentially affected the evolution of opsins in divergent amniote lineages.

Mercaptide conjugation in the uptake and secretion of sulfobromophthalein

1961 ◽  
Vol 200 (3) ◽  
pp. 545-547 ◽  
Author(s):  
J. R. Philp ◽  
G. M. Grodsky ◽  
J. V. Carbone
Keyword(s):  
Body Weight ◽  
Total Dose ◽  
Single Injection ◽  
Hepatic Cell ◽  
Secretion Rate ◽  
Free Form ◽  
Maximum Capacity ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

Sulfobromophthalein (BSP) was injected into rats, and the livers were excised at timed intervals. The ratio of free to mercaptide-conjugated BSP in the liver was determined after extraction and chromatographic separation. After 2 minutes, 12.5% of the total dose was concentrated in the liver; of this, 65% was free BSP. At 5 minutes, 33% of the total dose appeared in the liver, of which approximately 50% was still in the free form. Increasing concentrations of BSP were infused or administered as a single injection, and free and conjugated pigment appearing in the bile was measured. The maximum secretion rate for free BSP was 3–7 µg/ min/gm liver. Maximum capacity for secretion of conjugates was not reached, even when 60 mg BSP/kg body weight was administered. When purified metabolites were injected, they were rapidly secreted into the bile. It was concluded that uptake of BSP from the blood is a dynamic process which precedes and is relatively independent of the conjugation step. In contrast, conjugation may be the rate-limiting step in determining the secretion rate of the pigment from the hepatic cell.

In Vivo Effect of Heparin on Acid and Alkaline Ribonuclease Activities of Mouse Liver

1956 ◽  
Vol 184 (2) ◽  
pp. 415-417 ◽  
Author(s):  
Gaston De Lamirande ◽  
George Weber ◽  
Antonio Cantero
Keyword(s):  
Tissue Culture ◽  
Body Weight ◽  
Single Dose ◽  
Ribonucleic Acid ◽  
Mouse Liver ◽  
Single Injection ◽  
Coagulation Time ◽  
Alkaline Ribonuclease ◽  
Blood Coagulability

A single dose of 30 µg/gm body weight of depo-heparin was injected subcutaneously into white Swiss mice. At 1, 3, 6 and 12 hours after the injection, the blood coagulation time was measured and the activity of acid and alkaline ribonuclease of liver was determined. This single injection of depo-heparin significantly inhibited the acid and alkaline ribonucleases of liver 1 hour after injection. The enzymatic activities significantly increased after the blood coagulability was restored. The in vivo inhibition of acid and alkaline ribonuclease activity supports the explanation that the accumulation of ribonucleic acid in cells of tissue culture in the presence of heparin might be due to the inhibition of ribonuclease.

Deletion of the Impg2 gene causes the degeneration of rod and cone cells in mice

2020 ◽  
Vol 29 (10) ◽  
pp. 1624-1634
Author(s):  
Huijuan Xu ◽  
Chao Qu ◽  
Li Gan ◽  
Kuanxiang Sun ◽  
Junkai Tan ◽  
...  
Keyword(s):  
Cell Death ◽  
Er Stress ◽  
Molecular Mechanisms ◽  
Histopathological Examination ◽  
Apoptotic Cell ◽  
Macular Dystrophy ◽  
Cone Cell ◽  
Rod Cells ◽  
Cone Cells

Abstract Variants in interphotoreceptor matrix proteoglycans (IMPG2) have been reported in retinitis pigmentosa (RP) and vitelliform macular dystrophy (VMD) patients. However, the underlying molecular mechanisms remain elusive due to a lack of suitable disease models. We developed two independent Impg2 knockout (KO) mouse models using the CRISPR/Cas9 technique to assess the in vivo functions of Impg2 in the retina. Impg2 ablation in mice recapitulated the RP phenotypes of patients, including an attenuated electroretinogram (ERG) response and the progressive degeneration of photoreceptors. The histopathological examination of Impg2-KO mice revealed irregularly arranged rod cells and mislocalized rhodopsin protein in the inner segment at 6 months of age. In addition to the pathological changes in rod cells, cone cells were also affected in KO retinas. KO retinas exhibited progressive cone cell death and impaired cone cell elongation. Further immunoblotting analysis revealed increased levels of endoplasmic reticulum (ER) stress-related proteins, including C/EBP homologous protein (CHOP), immunoglobulin heavy-chain-binding protein (BIP) and protein disulfide isomerase (PDI), in Impg2-KO mouse retinas. Increased gliosis and apoptotic cell death were also observed in the KO retinas. As autophagy is closely associated with ER stress, we then checked whether autophagy was disturbed in Impg2-KO mouse retinas. The results showed that autophagy was impaired in KO retinas, as revealed by the increased accumulation of SQSTM1 and other proteins involved in autophagy. Our results demonstrate the essential roles of Impg2 in the retina, and this study provides novel models for mechanistic investigations and development of therapies for RP caused by IMPG2 mutations.

THE EFFECT OF CORTISOL ADMINISTRATION ON THE ACTIVITIES OF URIDINE AND DEOXYURIDINE PHOSPHORYLASES OF NORMAL AND REGENERATING RAT LIVER

1964 ◽  
Vol 42 (3) ◽  
pp. 317-325 ◽  
Author(s):  
Esther W. Yamada
Keyword(s):  
Body Weight ◽  
Partial Hepatectomy ◽  
Acid Metabolism ◽  
Single Injection ◽  
Sodium Succinate ◽  
Normal Liver ◽  
Fold Increase ◽  
Nucleic Acid Metabolism ◽  
Regenerating Liver ◽  
Uridine Phosphorylase

The phosphorolysis of uridine and deoxyuridine by homogenates of normal and regenerating liver of rats was assayed by a modification of the method of Canellakis (J. Biol. Chem. 227, 701 (1957)). By this assay the Kmvalues for uridine and deoxyuridine were 1.035 × 10−3 M and 2.95 × 10−4 M, respectively. The activities at an arsenate concentration of 0.114 M were 87 to 95% of the activities at an equivalent phosphate concentration.Forty-eight hours after partial hepatectomy the activity of uridine phosphorylase of regenerating liver was 1.1 times that of normal liver, and the activity of deoxyuridine phosphorylase of regenerating liver was 0.75 times that of normal liver. After a single injection of 9 mg of cortisol sodium succinate ester per 100 g of body weight there was a 1.8-fold increase in the activity of uridine phosphorylase but no significant increase in the activity of deoxyuridine phosphorylase of regenerating liver. After a single injection of 9 mg of cortisol per 100 g of body weight into normal rats there was a 1.6-fold increase in the activity of uridine phosphorylase and a 1.4-fold increase in the activity of deoxyuridine phosphorylase of normal liver. Thus, the phosphorolysis of uridine and deoxyuridine increases at different rates in liver after partial hepatectomy, or after cortisol, and this finding lends support to the view of others that the activities are due to two enzymes. The effect of cortisol, whether direct or indirect, in increasing the activities of the two enzymes in normal or regenerating liver would aid in the regulation of concentrations of intermediates of nucleic acid metabolism.

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