scholarly journals Turnover of myelin and other structural proteins in the developing rat brain

1974 ◽  
Vol 142 (3) ◽  
pp. 499-507 ◽  
Author(s):  
M. I. Sabri ◽  
A. H. Bone ◽  
A. N. Davison
Keyword(s):  
Rat Brain ◽  
Slow Component ◽  
Proteolipid Protein ◽  
Myelin Proteins ◽  
Turnover Rates ◽  
Basic Proteins ◽  
Glucose Injection ◽  
Total Brain ◽  
The Difference ◽  
Developing Rat

1. Protein metabolism of myelin and other subcellular components from developing rat brain was studied for periods from 5h to 210 days after intraperitoneal injection of [3H]lysine and [14C]glucose. 2. Half-lives for total brain proteins (t0.5) were 27 days after [3H]lysine and 4 days after [14C]glucose injection. 3. Factors accounting for the difference in the turnover rates obtained with different precursors, and the problem of reutilization of the label were investigated. 4. The catabolism of purified myelin proteins was studied and the half-lives of individual myelin proteins were calculated. 5. Myelin basic proteins turned over at two different rates. Half-life of the fast component of myelin basic proteins was 19–22 days and the slow component exhibited a high degree of metabolic stability. 6. Proteolipid protein underwent slow turnover. High-molecular-weight Wolfgram (1966) proteins underwent (relatively) fast metabolism (t0.5 of 17–22 days).

scholarly journals Differentiation and Death of Premyelinating Oligodendrocytes in Developing Rodent Brain

1997 ◽  
Vol 137 (2) ◽  
pp. 459-468 ◽  
Author(s):  
Bruce D. Trapp ◽  
Akiko Nishiyama ◽  
David Cheng ◽  
Wendy Macklin
Keyword(s):  
Cerebral Cortex ◽  
Corpus Callosum ◽  
Rat Brain ◽  
Protein Gene ◽  
Proteolipid Protein ◽  
Gene Products ◽  
Rodent Brain ◽  
Developing Rat

Previous studies have indicated that newly formed oligodendrocytes are dynamic cells whose production, survival, and differentiation depend upon axonal influences. This study has characterized the appearance and fate of newly formed oligodendrocytes in developing rat brain. Oligodendrocytes appear in predictable locations and radially extend DM-20–positive processes that cover 80-μm domains in the cortex and 40-μm domains in the corpus callosum. These premyelinating oligodendrocytes have one of two fates: they myelinate axons or degenerate. Between 7 and 21 d after birth, ∼20% of premyelinating oligodendrocytes identified in the cerebral cortex were degenerating. Oligodendrocytes that ensheathed axons expressed and selectively targeted proteolipid protein to compact myelin and did not degenerate. These observations support the hypothesis that axonal influences affect oligodendrocyte survival, differentiation, and expression of proteolipid protein gene products.

Influence of thyroid hormones on myelin proteins in the developing rat brain

1975 ◽  
Vol 25 (1) ◽  
pp. 19-27 ◽  
Author(s):  
T. Valcana ◽  
E.R. Einstein ◽  
J. Csejtey ◽  
K.B. Dalal ◽  
P.S. Timiras
Keyword(s):  
Thyroid Hormones ◽  
Rat Brain ◽  
Myelin Proteins ◽  
Developing Rat

scholarly journals Effect of phenylalanine on protein synthesis in the developing rat brain

1970 ◽  
Vol 117 (2) ◽  
pp. 325-331 ◽  
Author(s):  
H. C. Agrawal ◽  
A. H. Bone ◽  
A. N. Davison
Keyword(s):  
Amino Acids ◽  
Rat Brain ◽  
Free Amino ◽  
Myelin Proteins ◽  
Free Amino Acid Pool ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Old Rats ◽  
Developing Rat ◽  
The Brain

1. Inhibition of the rate of incorporation of [35S]methionine into protein by phenylalanine was more effective in 18-day-old than in 8-day-old or adult rat brain. 2. Among the subcellular fractions incorporation of [35S]methionine into myelin proteins was most inhibited in 18-day-old rat brain. 3. Transport of [35S]methionine and [14C]leucine into the brain acid-soluble pool was significantly decreased in 18-day-old rats by phenylalanine (2mg/g body wt.). The decrease of the two amino acids in the acid-soluble pool equalled the inhibition of their rate of incorporation into the protein. 4. Under identical conditions, entry of [14C]glycine into the brain acid-soluble pool and incorporation into protein and uptake of [14C]acetate into lipid was not affected by phenylalanine. 5. It is proposed that decreased myelin synthesis seen in hyperphenylalaninaemia or phenylketonuria may be due to alteration of the free amino acid pool in the brain during the vulnerable period of brain development. Amyelination may be one of many causes of mental retardation seen in phenylketonuria.

scholarly journals Accumulation and turnover of the classical Folch-Lees proteolipid proteins in developing and adult rat brain

1976 ◽  
Vol 154 (2) ◽  
pp. 265-269 ◽  
Author(s):  
H C Agrawal ◽  
K Fujimoto ◽  
R M Burton
Keyword(s):  
Rat Brain ◽  
Half Life ◽  
Specific Radioactivity ◽  
Proteolipid Protein ◽  
Total Radioactivity ◽  
Myelin Proteins ◽  
Subcutaneous Injections ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Proteolipid Proteins

The turnover of classical Folch-Lees proteolipid proteins was studied after administration of [2,3-3H]tryptophan to both developing and adult rat brain. The animals were killed from 2h to 250 days after subcutaneous injections of [3H]tryptophan. The measured specific radioactivity in developing brain attained maximum value 24h after the administration of label, whereas the total radioactivity per brain reached a maximum 21 days after injection. The half-life of proteolipid protein from the measured specific radioactivity was 7-20 days, depending on the time-points used for the calculation, whereas calculation from total radioactivity between 28-77 and 91-257 days gave half-lives of 35-40 and 188 days respectively. In contrast, in animals injected at 40 days of age, the half-life from the whole-brain-radioactivity data was 188 days. The problem of the recycling of radioactivity for the synthesis of myelin proteins from either a general or a discrete amino acid pool is discussed.

scholarly journals UDP-galactose-ceramide galactosyltransferase in rat brain myelin subfractions during development

1980 ◽  
Vol 186 (3) ◽  
pp. 959-969 ◽  
Author(s):  
O Koul ◽  
K H Chou ◽  
F B Jungalwala
Keyword(s):  
Rat Brain ◽  
Membrane Fraction ◽  
Specific Activity ◽  
Gradient Centrifugation ◽  
Proteolipid Protein ◽  
Myelin Proteins ◽  
Sucrose Density Gradient Centrifugation ◽  
Microsomal Membranes ◽  
Myelin Subfractions ◽  
Myelin Fraction

The localization and activity of the enzyme UDP-galactose-hydroxy fatty acid-containing ceramide galactosyltransferase is described in rat brain myelin subfractions during development. Other lipid-synthesizing enzymes, such as cerebroside sulphotransferase, UDP-glucose-ceramide glucosyltransferase and CDP-choline-1,2-diacylglycerol cholinephosphotransferase, were also studied for comparison in myelin subfractions and microsomal membranes. The purified myelin was subfractionated by isopycnic sucrose-density-gradient centrifugation. Four myelin subfractions, three floating respectively on 0.55 M- (light-myelin fraction), 0.75 M- (heavy-myelin fraction) and 0.85 M-sucrose (membrane fraction), and a pellet, were isolated and purified. At all ages, 70-75% of the total myelin proteins was found in the heavy-myelin fraction, whereas 2-5% of the protein was recovered in the light-myelin fraction, and about 7-12% in the membrane fraction. Most of the galactosyltransferase was associated with the heavy-myelin and membrane fractions. Other lipid-synthesizing enzymes studied appeared not to associate with purified myelin or myelin subfractions, but were enriched in the microsomal-membrane fraction. During development, the specific activity of the microsomal galactosyltransferase reached a maximum when the animals were about 20 days old and then declined. By contrast the specific activity of the galactosyltransferase in the heavy-myelin and membrane fractions was 3-4 times higher than that of the microsomal membranes in 16-day-old animals. The specific activity of the enzyme in the heavy-myelin fraction sharply declined with age. Chemical and enzymic analyses of the heavy-myelin and membrane myelin subfractions at various ages showed that the membrane fraction contained more proteins in relation to lipids than the heavy-myelin fraction. The membrane fraction was also enriched in phospholipids compared with cholesterol and contrined equivalent amounts of 2':3'-cyclic nucleotide 3'-phosphohydrolase compared with heavy- and light-myelin fractions. The membrane fraction was deficient in myelin basic protein and proteolipid protein and enriched in high-molecular-weight proteins. The specific localization of galactosyltransferase in heavy-myelin and membrane fractions at an early age when myelination is just beginning suggests that it may have some role in the myelination process.

Study of expression of myelin basic proteins (MBPs) in developing rat brain using a novel antibody reacting with four major isoforms of MBP

2002 ◽  
Vol 68 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Kyoichi Akiyama ◽  
Sachiyo Ichinose ◽  
Akira Omori ◽  
Yoko Sakurai ◽  
Hiroaki Asou
Keyword(s):  
Rat Brain ◽  
Basic Proteins ◽  
Developing Rat
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