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  • 1
    Electronic Resource
    Electronic Resource
    Effect of Monomethylethanolamine, Dimethylethanolamine, Gangliosides, Isoproterenol, and 2-Hydroxyethylhydrazine on the Conversion of Ethanolamine to Methylated Products by Cultured Chick Brain Neurons (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The sequential methylation of ethanolamine and its phosphorylated derivatives has been studied with chick neurons in culture in the presence of several pharmacological agents. Incubation with [3H]ethanolamine in the presence of monomethylethanolamine and dimethylethanolamine indicated that in these neurons the preferential conversion to choline-containing compounds is via the methylation of phosphorylethanolamine. The possibility that there are two separate enzymes, i.e., one responsible for the methylation of water-soluble ethanolamine-containing compounds and another for the ethanolamine phospholipids, was examined with agents believed to influence these conversions. Incubation of neurons in the presence of a mixture of exogenous gangliosides at 10−8M and 10−5M concentrations showed that these neuritogenic compounds stimulate the methylation of phosphatidylethanolamine and decrease that of phosphorylethanolamine. The inhibitor of phosphatidylethanolamine methyltransferase (EC 2.1.1.17), 2-hydroxyethylhydrazine, decreased the conversion of phosphatidylethanolamine to phosphatidylcholine and increased that of phosphorylethanolamine to phosphorylcholine. The possible effects of adrenergic stimulation were studied by the incubation of neurons with isoproterenol at 10−6M and 10−5M concentrations. There was a reduction of phosphorylethanolamine methylation and a stimulation of that of phosphatidylethanolamine, and these effects were counteracted by the presence of 5 × 10−5M propranolol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb03439.x
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular Species of Choline and Ethanolamine Phospholipids in Rat Cerebellum During Development (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The molecular species composition of rat cerebellar phospholipid subclasses has been studied by HPLC after phospholipase C treatment and dinitrophenyl derivatization. During rat cerebellum development (3–90 days postpartum), cholinephosphoglycerides and ethanolamine phosphoglycerides represented ∼80% of all phospholipids, with their relative amount changing after 1 month. Among ethanolamine phosphoglycerides, the molar ratio of diacylglycerophosphoethanolamine (diacylGPE) to alkenylacylGPE decreased from ∼1.4 at 3 days to ∼0.5 after 10 days. The phospholipids investigated contained up to 12 different molecular species. The rate of accumulation of the various molecular species of diacylglycerophosphocholine (diacylGPC), diacylGPE, and alkenylacylGPE during cerebellar development allowed a classification into three main groups. The overall increase of the molecular species of the first group (6-diacylGPC, 5-diacylGPE, and 4-alkenylacylGPE) was ∼ 18-fold between 3 and 90 days, with a faster rate of accumulation between 3 and 30 days. Those of the second group (3-diacylGPC, 5-diacyl-GPE, and 5-akenylacylGPE) increased by ∼45-fold during the same developmental period, at a slow rate before day 15 and at a faster one thereafter. The molecular species of the third group (3-alkenylacylGPE) increased by 〉250-fold between 3 and 90 days, at a very slow rate before day 21 and more quickly thereafter. The different rates of accumulation of the components of the three groups during cerebellar development suggest a preferential location of the first group in membranes of neuronal perikaryons, glial cells, and synaptosomal structures. Those of the second group appear to be located in both synaptosomal membranes and myelin sheets, and those of the third group can be considered as myelin markers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb01221.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of CDP-Choline on Hypocapnic Neurons in Culture (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neuronal cultures from chick embryo cerebral hemispheres were protected against a hypocapnic injury by adding to their growth medium 10--6M CDP-choline before or after the injury. The protection obtained with CDP-choline was analyzed by a morphometric analysis and showed that pretreatment of neuronal cultures with CDP-choline maintained the number of cell aggregates and of primary neuronal processes at control values after hypocapnic shock. Various experiments showed that the intact molecule was responsible for the protective action, since pretreatment with different concentrations of various nucleosides and nucleotides (up to 10--5M), choline, and phosphorylcholine was without protective effect. The addition of CDP-choline after the hypocapnic injury resulted in a protection of the cultures as shown by morphological observation. Incubation of neurons with radioactive choline showed that hypocapnia increased the incorporation of the label into phospholipids whereas the presence of CDP-choline reduced it. The de novo synthesis of choline was affected by neither hypocapnia nor CDP-choline treatment. The results indicate that CDP-choline may have the capacity to protect neurons under conditions of basic pH and that cellular proliferation may be stimulated by the compound.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb02853.x
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular Species Analysis of 1,2-Diglycerides on Phorbol Ester Stimulation of LA-N-1 Neuroblastoma Cells During Proliferation and Differentiation (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 65 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: 1,2-Diacyl-sn-glycerol (DAG) is a product of cell activation that has emerged as an important intracellular messenger whose primary function appears to be the activation of protein kinase C. They originate by the activation of phospholipases, which hydrolyze different phospholipids depending on the external stimulus and the nature of the cells, leading to the production of different molecular species. In the present study the quantitative changes in the total mass and the molecular species of DAG formed on phorbol ester (12-O-tetradecanoylphorbol 13-acetate) stimulation were investigated in proliferating and retinoic acid (RA)-differentiated human LA-N-1 cells. The TPA treatment of both cell types elicited an increase in the total amount of DAG. The increase was biphasic; i.e., an initial peak at 2–5 min was followed by a sustained increase that persisted for 〉30 min. The analysis of the molecular species of DAG and phospholipids showed that in proliferating LA-N-1 cells, the DAG increase corresponds to the production of mainly saturated/monounsaturated (16:0–18:1, 18:0–18:1) and saturated/saturated (16:0–16:0, 16:0–18:0) species, suggesting that they originate essentially from the hydrolysis of phosphatidylcholine. In contrast, RA-differentiated cells responded to TPA treatment by increasing the level of saturated/polyunsaturated (16:1–22:6, 18:0–22:6, 16:0–20:4, 18:0–20:4) and monounsaturated/monounsaturated (18:1-18:1) species, suggesting mainly a phosphatidylethanolamine origin. These findings indicate that the treatment of LA-N-1 cells with TPA generates different molecular species of DAG depending on their physiological state. These observations suggest in turn that different phospholipases are activated by TPA in proliferating and RA-differentiated cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.65020810.x
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  • 5
    Electronic Resource
    Electronic Resource
    EFFECT OF LIGHT ON GANGLIOSIDES FROM CALF RETINA AND PHOTORECEPTORS (1974)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 22 (1974), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —The gangliosides of the whole calf retina and the rod outer segments have been analysed. This has been done in two functional states: before and after stimulation by light. After exposure to light no statistically significant change in the gangliosides of the whole retina was observed, but a 40 per cent increase in concentration was found in the rod outer segments. This difference was apparent only when using the same batch of rod outer segments. The major ganglioside in the whole calf retina is GD3 which accounts for 46 per cent of the total. Three other gangliosides GD1a, GD1b and GT1 are quantitatively important, each being between 12 and 16 per cent. GQ1, GM1, and GM3 are minor constituents. In contrast to the chicken retina, GM2 was not detected. The ganglioside N-acetylneuraminic acid of the rod outer segments accounts for only 1 per cent of the gangliosides of the whole retina. The composition of the gangliosides in the rod outer segments is essentially the same as that of the whole retina. No difference in the relative proportion of the gangliosides of either the rod outer segments or the whole retina was observed after exposure to light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1974.tb04339.x
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  • 6
    Electronic Resource
    Electronic Resource
    Neuraminidase in Calf Retinal Outer Segment Membranes (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 40 (1983), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: An enzyme catalyzing the hydrolysis of sialic acid (N-acetylneuraminic acid: NeuNAc)-containing glycoconjugates has been found in bovine retinal rod outer segment (ROS) membranes. The enzymatic activity is optimal at pH 4.0 and is stimulated by 0.15% Triton X-100. Total activity was determined by the release of NeuNAc from endogenous and exogenous substrates (GDla). The ROS enzyme preferentially hydrolyses the ROS gangliosides, possibly because they are more accessible than the glycoproteins as substrates for the neuraminidase. Release of NeuNAc from gangliosides leads to important changes in the ganglioside patterns; whereas the amounts of GM1 increased throughout the incubation, the levels of polysialogangliosides GTlb and GD3 diminished owing to their rapid hydrolysis. The finding that gangliosides are hydrolysed more extensively than glycoproteins suggests that endogenous ROS gangliosides may be the principal source of metabolically available sialic acid in ROS. It was also observed that the activity of ROS neuraminidase is not affected by illumination of the membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1983.tb12669.x
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  • 7
    Electronic Resource
    Electronic Resource
    Topographic Distribution of Enzymes Synthesizing Phosphatidylcholine and Phosphatidylethanolamine in Chicken Brain Microsomes (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 38 (1982), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The localization of phosphatidylethanolamine and phosphatidylcholine biosynthetic enzymes within the transverse plane of chicken brain microsomes was investigated by using proteases (trypsin and pronase) and neuraminidase. Treatment of intact microsomes with the proteases inactivated the phosphocholine transferase completely and the ethanolamine phosphotransferase only slightly. This latter enzyme was, however, completely inactivated when deoxycholate-treated microsomes were exposed to proteases. Treatment of intact microsomes with neuraminidase had no effect on both phosphotransferases, although 65% of the sialic acid of sialoglycoproteins and 37% of that of gangliosides were removed. With deoxycholate-disrupted microsomes nearly all sialic acid from the sialoglycoproteins and about 70% of that of gangliosides were released. In parallel, the phosphoethanolamine transferase was 90% inactivated. It is suggested that phosphocholine transferase is localized on the outer face of the microsomal vesicle, whereas the phosphoethanolamine transferase could be a sialoglycoprotein, possibly situated on the inner face of the vesicle, or perhaps a transmembrane protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1982.tb08666.x
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  • 8
    Electronic Resource
    Electronic Resource
    ENZYMATIC BIOSYNTHESIS OF ETHANOLAMINE- AND CHOLINE-PHOSPHOGLYCERIDES IN RETINA DURING DEVELOPMENT. EFFECT OF LIGHT STIMULATION (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 31 (1978), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Choline- and ethanolamine-phosphoglycerides (CPG and EPG) are the most abundant phospholipids of retinal membranes. We have investigated some regulatory mechanisms involved in the final steps of their biosynthesis, namely those catalysed by CDP-choline 1,2 diradyl-sn-glycerol choline phosphotransferase (CPT) and CDP-ethanolamine 1,2 diradyl-sn-glycerol ethanolamine phosphotransferase (EPT). We have studied both enzymes in the retina which offers an excellent model for the investigation of the molecular basis of the effect of its physiological stimulus, the light. In chick retina. the specific activity (SA) of EPT reached a maximum at the 18th day of embryonic life and decreased thereafter. In the case of CPT, a similar peak of SA was observed at hatching. The time of maximum SA of EPT and CPT corresponded to the period during which retinal rod outer segments are formed. The apparent Km values of EPT and CPT determined with whole retinal homogenates for CDP-bases showed different profiles. The apparent Km of EPT decreased during embryonic life and increased thereafter whereas the apparent Km of CPT did not change during ontogenesis. Light stimulation of calf retinal homogenates had different effects on phosphotransferase activities. In the presence of only endogenous diacylglycerol (DAG) the SA of CPT was 2-fold higher for dark-adapted retinas, whereas no differences in EPT activities were observed. After addition of exogenous DAG (4mM) to the incubation medium, light stimulation of the retina led to a 50% increase of EPT activity whereas no effect was observed for CPT. These different effects could be related to the cyclic nucleotides present in retina before and after light stimulation. In addition all the data presented in this study indicate that, as in brain, CPT and EPT in retina are two different enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1978.tb06239.x
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  • 9
    Electronic Resource
    Electronic Resource
    PHOSPHOLIPID METABOLISM IN LIGHT AND DARK ADAPTED EXCISED RETINA (1973)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 20 (1973), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The phospholipid composition of, and the incorporation of labelled phosphorus into the different phospholipids of rat and calf retina have been studied. The influence of various conditions, such as dark and light adaptation, during the preparation of retina, lipid extraction and incubation of retina with radioactive phosphorus was investigated.The phospholipid composition of rat retina did not differ significantly from that of calf retina and the different conditions of preparation and incubation did not modify the distributions.The specific radioactivities of the different phospholipids of calf and rat retina, incubated in the presence of 32P, distinguished in both species two groups of components characterized by the rate of labelling. Phosphatidic acid (PA) and inositol glycerophospholipids (PI) belonged to the first group and showed the highest uptake of labelled phosphorus; the second group, comprising choline glycerophospholipids (PC), serine glycerophospholipids (PS), sphingomyelin (SP), ethanolamine glycerophospholipids (PE) and cardiolipin (CL) showed low incorporation activities. Only SP was labelled differently in rat and calf retina. With the exception of PS, there was no evidence for the influence of light on the turnover of individual phospholipids. The finding that PS showed higher specific radioactivities when adaptation and incubation proceeded in the dark, seems to be of interest and needs further study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1973.tb12132.x
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  • 10
    Electronic Resource
    Electronic Resource
    SULPHOLIPID METABOLISM IN DEVELOPING CHICKEN RETINA (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 30 (1978), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Glycolipid analysis of chicken retina and brain indicated the presence of cerebroside, cerebroside 3-sulphate and sulphogalactosylglycerolipid In retina, the ratio of cerebroside to cerebroside 3-sulphate was approximately half compared to brain. During chicken retina ontogenesis the ratio of cerebroside 3-sulphate to sulphogalactosylglycerolipid increased rapidly and in the adult animal, the amount of cerebroside 3-sulphate was 14 times higher than that of sulphogalactosylglycerolipid.The activity of PAPS: cerebroside sulphotransferase and arylsulphatase A in developing chicken retina indicated that the general ontogenic profiles of retinal PAPS: cerebroside sulphotransferase and arylsulphatase A were similar to those obtained for the brain. Both the enzymes showed the highest activity just before hatching. The significance of occurrence of sulpholipids in retina is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1978.tb07048.x
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