摘要:

Abstract—The cerebral cortex of the rat was submitted to an extensive cell fractionation schedule and in the various fractions, protein, proteolipid protein, total phospholipids, cholesterol, galactolipids, plasmalogens, and gangliosides were determined. With increasing purification the different isolated membranous structures: i.e. myelin, nerve ending membranes, synaptic vesicles, mitochondria, and microsomes, show a definite biochemical specialization reflected in their lipid composition. The presence of gangliosides in some nerve ending membranes is confirmed, and the possible functional role of these acid glyco‐lipids is discussed.The importance of proteolipids as structural components of membranes is recognized. The richness of these compounds in myelin is confirmed and a special localization in the nerve ending membranes is indicated.Analysis of the molar ratios of the different lipids and proteins in the isolated membranes demonstrates that each one has a specific pattern of molecular organization. This pattern is discussed in relation to the macromolecular structures revealed by electronmicroscopy and some of the molecular models postulated for cell membra

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08939.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Damage to the brain as a result of an intracerebral injection of physiological saline does not appreciably affect the rate of protein synthesis in mouse brain. Thein vivoandin vitroincorporation of labelled amino acids into mitochondria and theirin vivoincorporation into nuclei, microsomes, nerve ending particles, myelin and cell sap were compared in normal and scrapie‐affected mice. No significant differences were fo

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08940.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The time‐course of development of sulphate and iodide transport mechanisms in choroid plexus was studied by measuring uptake of [35S]sulphate and [125I]iodide from an incubating medium by isolated choroid plexuses of foetal and newborn rabbits and cats. Sulphate uptake by choroid plexus was poorly developed in rabbit foetuses just before term, but highly developed in newborn animals. Iodide uptake was already well developed in the most immature foetuses stud

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08941.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—(1) Acute hypoxia was produced in adult rats by cyanide inhalation and the effect on the active transport of amino acids was studied in brain slices.(2) Initial and steady‐state accumulation of amino acids and rates of amino acid exit were identical in brain slices from control and treated animals when a glucose‐containing incubation medium was used.(3) When the incubation was carried out in a glucose‐free incubation medium, the inhibition of initial and steady‐state accumulation and the stimulation of amino acid exit observed in control slices were significantly reduced or abolished in slices from treated animals.(4) Tissue swelling, size of ‘inulin space’ and glucose consumption did not differ in the two groups of animals.(5) Also the respiration rate was identical in slices from control and treated animals incubated in the presence of glucose. In the absence of added substrate, brain slices from treated animals consumed 15‐20 per cent more oxygen than control slices.(6) A possible correlation between the effects observed on amino acid transport and on respiration is suggested. The reasons why cyanide givenin vivoor addedin vitrohave different effects on amino acid transport in brain slice

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08942.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Myelin osmiophilia has been shown to develop significantly later than myelin staining by Luxol fast blue and Sudan black, in the developing kitten optic nerve. These histological changes are accompanied by alterations in the lipid composition of the optic nerve. Although myelination commences at about 10 days post partum in the nerve the appearance of cerebrosides is unexpectedly delayed. Changes in fatty acid chain length and lipid composition of optic nerve are consistent with the suggestion that ‘early’ myelin may be unchanged glial plasma mem

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08943.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Two distinctly different DNases were isolated from rat brain and could be separated easily by ammonium sulphate fractionation. One of the DNases acts optimally at pH 5.0 hydrolysing preferentially native DNA and requiring an optimal Mg2+concentration of about 0.03m. The other DNase has its optimal pH between 7.4 and 8.9, acts preferentially on heat‐denatured DNA and requires a lower Mg2+concentration, the optimum being 1 × 10−4m.Cerebellum from adult rat brain has a lower acid DNase activity and higher alkaline DNase activity, and therefore has a higher ratio of alkaline DNase to acid DNase than the other areas of brain studied. This unique activity ratio in cerebellum of adult rat brain was not observed in infant rat

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08944.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Myelin was isolated from the brains of mice at ages of 14, 24, 41, 44, 47, and 182 days and the contents of lipid phosphorus, cholesterol, lipid galactose, alkenyl groups, ethanolamine phosphoglycerides, choline phosphoglycerides, sphingomyelin, and serine and inositol phosphoglycerides were determined. Significant differences in the composition relative to total lipid phosphorus were found in the myelin. At 14 days of age, the myelin had lower relative amounts of cholesterol, galactolipids, alkenyl groups, and ethanolamine phosphoglycerides and a higher relative amount of choline phosphoglyceride

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08945.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The incorporation of uridine into RNA in brain slices was studied. Optimal conditions for uridine incorporation were determined. The characteristics of the product suggest thatde novoDNA‐directcd synthesis of fairly high molecular weight material takes place. Incorporation into RNA of several areas of brain was studied. The incorporation was also studied as a function of the age of the animal. Finally, an apparent correlation was observed between the decrease in uridine incorporation with age and the increase of the enzyme uridine nucleosidase which hydrolyses uridine to uracil, a material which cannot be incorporated into

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08946.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—(1) The subcellular distributions of Na‐K ATPase and [14C]ADP‐ATP exchange activities were studied in rat brain. The data presented are not consistent with a discrete localization of these enzymes in any given fraction, but nerve endings and microsomes had similar specific activities. The supernatant fraction had the highest exchange and the lowest Na‐K ATPase activities, measured at a concentration of 3 mm‐MgCl2.(2) Nucleotide specificity of the Na‐K ATPase was determined in all fractions, and this enzyme system showed an absolute requirement for ATP. The [14C]ADP‐ATP exchange, measured at 3mm‐MgCl2, possessed broader specificity and also was active toward ITP, UTP and GTP; this serves to differentiate it from the Na‐K ATPase.(3) Treatment of nerve ending fractions with NaI medium removed the bulk of the [14C]ADP‐ATP exchange activity without loss in Na‐K ATPase activity.(4) The exchange activity in NaI‐insoluble fractions was insensitive to NaCl in the presence of 3 mm‐MgCl2, but it was stimulated 502‐820 percent at low MgCl2concentrations, a finding which may be consistent with the postulated role of this exchange reactio

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08947.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—An ADP‐ATP exchange reaction was studied in NaI‐treated microsomes from rat brain. At low concentrations of MgCl2a nucleotide exchange reaction, elicited in the presence of Na+, had an absolute specificity for ATP. The reaction was stimulated by oligomycin and inhibited by ouabain and EDTA. It is probable that this Na+‐stimulated ADP‐ATP exchange reaction is a component of the Na‐K AT

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb08948.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY