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Biomedical subjects

I Serra

Publications and source records attributed to I Serra.

At least 55 records · Page 3Linked to original sources
PubMed1983

Post-translational changes of chromosomal proteins in rat cerebellum during postnatal development.

Acetylation, phosphorylation and methylation of nuclear proteins in rat cerebellum at 10 and 30 days of age were investigated in vitro. Isolated nuclei were incubated in the presence of [1-14C]acetyl CoA, S-adenosyl [methyl-3H]methionine and [gamma-32P]ATP and then separated into histones and non histone proteins (NHP), which were further fractionated by polyacrylamide gel electrophoresis. The results obtained indicate that acetylation, phosphorylation and methylation of both basic and acidic proteins decrease from 10 to 30 days of age. Electrophoretic analysis of histones shows that the decrease mainly concerns H1, H3, and H2b fractions. The H3 fraction is always more labeled than the other fractions and shows the major changes during postnatal development. Phosphorylation of H2a and H4 fractions increases from 10 to 30 days of age, whereas acetylation and methylation of these fractions do not show significant changes from 10 to 30 days. The densitometric and radioactive patterns of NHP show considerable changes between 10 and 30 days, especially in the high molecular weight region. The incorporation of 14C-acetyl and 3H-methyl groups and of 32P phosphate appears to be generalized throughout the molecular weight range and decreases from 10 to 30 days of age. The methylation of an as yet unidentified protein with a molecular weight of approximately 110,000 daltons occurred at both ages.

Acetylation↗
PubMed1983

Labeling of RNA in young and adult rat brain: evidence for different RNA processing.

The labeling of RNA in young and adult rat brain has been studied by measuring in vitro (tissue slices incubation) the incorporation of labeled uridine into RNA of total tissue and of the various subcellular fractions purified from cerebral hemispheres of 1- and 10-month-old rats. Gel electrophoretic analysis of the newly synthesized nuclear and microsomal RNA was also accomplished. An active metabolism of RNA in adult animals was found; moreover, distinct differences in ribosomal RNA processing in cerebral hemispheres of 1- and 10-month-old rats, with a more rapid processing in the brain of adult animals, were obtained.

Aging↗
PubMed1983

Posttranslational modifications of nuclear proteins in rat cerebral hemispheres during postnatal development.

The processes of acetylation, phosphorylation, and methylation of nuclear proteins in cerebral hemispheres of 10- and 30-day-old rats were investigated. The experiments were carried out in vitro by measuring the incorporation of labeled precursors into histones and nonhistone chromosomal proteins (NHP) extracted from nuclei and separated by polyacrylamide gel electrophoresis. The results obtained indicate that there are age-specific differences in the processes of phosphorylation and methylation of chromosomal proteins, whereas the acetylation process did not change significantly between 10 and 30 days of age. Electrophoretic analysis of histones indicated that the histone H3 was labeled to a greater degree than the other fractions and showed major changes in the processes of phosphorylation and methylation during postnatal development. The electrophoretic analysis of NHP showed considerable changes between 10 and 30 days of age. Certain components of NHP became increasingly evident as the brain developed. The methylation of an as yet unidentified protein with a molecular weight of approximately 118,000 daltons occurred at both ages.

Acetylation↗
PubMed1982

De novo biosynthesis of nucleotides and of nucleic acids in different regions of developing rat brain: effect of undernutrition.

The effect of undernutrition on the de novo biosynthesis of nucleic acids in cerebral hemispheres, cerebellum, and brain stem of rats at different days of postnatal development was studied. The experiments were carried out in vitro by measuring the incorporation of [14C]-formate into the adenine nucleotide of the acid-soluble fraction of RNA and DNA, as well as into the thymine of DNA. The results obtained indicate that undernutrition during fetal and postnatal development impairs the de novo synthesis of the purine nucleotides of RNA and DNA at 5 days of age and delays it thereafter in the various brain regions examined, particularly in the cerebellum.

Adenine↗
PubMed1982

Effect of undernutrition on DNA and RNA synthesis in subcellular fractions from different regions of the developing rat brain.

The effect of undernutrition on the incorporation of [methyl-3H] thymidine into DNA and of 5-[3H] uridine into RNA of cerebral hemispheres, cerebellum, and brain stem was studied in vivo and in vitro in rats. The labeling of DNA from nuclei and mitochondria and of RNA from nuclei, mitochondria, microsomes, and soluble fractions, was also measured in vitro. The results demonstrate that nucleic acid synthesis is impaired and delayed during undernutrition. Specific effects were observed for the different brain regions and subcellular fractions: at 10 days nuclear and mitochondrial DNA and RNA synthesis was impaired, whereas at 30 days only the mitochondrial nucleic acid synthesis was affected. The delay of DNA and RNA labeling, caused by undernutrition, was most evident in the cerebellum, probably due to its intense cell proliferation during postnatal development. The specific sensitivity of mitochondria as compared to other subcellular fractions, may by due to the intense biogenesis and/or turnover of nucleic acids in brain mitochondria not only during postnatal development, but also in the adult animal.

Animals↗
PubMed1982

DNA polymerase and thymidine kinase activities in different regions of rat brain during postnatal development: effect of undernutrition.

The effect of undernutrition on the activity of two key enzymes for DNA synthesis, namely DNA polymerase and thymidine kinase, in developing rat brain has been investigated. Both enzymatic activities in cerebral hemispheres and in brain stem are lower in undernourished animals than in controls at the 5th day after birth; successively, from 5 to 30 days, they decrease in both groups of animals, however the decrease is less drastic in undernourished rats than in controls. At 30 days of age the specific activity of both enzymes is quite similar in the two groups of animals. In the cerebellum, DNA polymerase and thymidine kinase activities increase after 5 days of age showing a peak at around 9 days in controls and at about 13 days in undernourished animals, decreasing thereafter in both groups, although less drastically in undernourished animals, and reaching quite similar values at 30 days. The results obtained show that both enzymatic activities are impaired at 5 days and delayed thereafter, in agreement with the changes of DNA synthesis previously observed.

Animals↗
PubMed1981

Effect of CDP-choline on the biosynthesis of phospholipids in brain regions during hypoxic treatment.

Acute administration of CDP-choline (i.p. 100 mg/Kg b.w.), 10 min before the intraventricular injection of labeled precursors, [2-3H] glycerol and [1-14C]-palmitate, was able to correct the impairment caused by hypoxic treatment of lipid metabolism in some brain regions, ie, cerebral hemispheres, cerebellum, and brainstem. After CDP-choline treatment, an increase of the specific radioactivity of total lipids and of phospholipids was observed in mitochondria purified from the three above-mentioned brain regions of the hypoxic animals, while no effect on the other subcellular fractions was found. CDP-Choline had a stimulating effect particularly on the incorporation of both precursors into mitochondrial PC, PE, and polyglycerophosphatides isolated form the three brain regions examined. The results obtained show that the action of CDP-choline in restoring lipid metabolism was more pronounced in brain mitochondria, which, among subcellular fractions, were the most affected by the hypoxic treatment.

Animals↗
PubMed1981

Effect of CDP-choline on the biosynthesis of nucleic acids and proteins in brain regions during hypoxia.

The effect of CDP-choline on the in vivo incorporation of labeled precursors into DNA, RNA, and proteins in cerebral hemispheres, cerebellum, and brainstem of guinea pigs after hypoxic treatment was studied. The labeling of macromolecules extracted from the various subcellular fractions of these brain regions was also determined. Hypoxic treatment affected macromolecular labeling to a different extent in the three brain regions examined. CDP-choline treatment was not able to reverse the effect of hypoxia on DNA labeling, but it was able to remove the effect of hypoxia on RNA and protein labeling. The action of CDP-choline was particularly evident on the labeling of RNA in nuclei and mitochondria of the cerebellum and on the labeling of proteins in microsomes of the three brain regions examined.

Animals↗
PubMed1981

Effect of hypoxia on nucleic acid and protein synthesis in different brain regions.

The incorporation of [methyl-3H]thymidine into DNA, of [5-3H]uridine into RNA, and of [1-14C]leucine into proteins of cerebral hemispheres, cerebellum, and brainstem of guinea pigs after 80 hr of hypoxic treatment was measured. Both in vivo (intraventricular administration of labeled precursors) and in vitro (tissue slices incubation) experiments were performed. The labeling of macromolecules extracted from the various subcellular fractions of the above-mentioned brain regions was also determined. After hypoxic treatment the incorporation of the labeled precursors into DNA, RNA, and proteins was impaired to a different extent in the three brain regions and in the various subcellular fractions examined; DNA and RNA labeling in cerebellar mitochondria and protein labeling in microsomes of the three brain regions examined were particularly affected.

Animals↗
PubMed1980

Effects of undernutrition on nucleic acid synthesis in neuronal and glial cells from different regions of developing rat brain.

Rats were undernourished by being given half their normal diet from the 10th day of pregnancy, 10-, 15- and 30-day-old rats were studied. Incorporation of labelled precursors into brain DNA and RNA was carried out in vitro with slices from cerebral cortex, brain stem and cerebellum. Neuronal and glial cells were subsequently isolated and analyzed for specific radioactivity. The proliferation and differentiation of all brain cells were affected by undernutrition. Glial cells in particular and the small neuronal cells appeared most vulnerable probably because of their intense postnatal development.

Animals↗
PubMed1979

Macromolecular synthesis in mitochondria isolated from different regions of developing rat brain.

DNA, RNA, and protein synthesis in mitochondria isolated from cerebral hemispheres, brain stem, and cerebellum of 10- and 30-day-old rats was measured. Synthesis of different macromolecules was affected by the respective mitochondrial specific inhibitors, showing a good level of purity of mitochondrial preparations. DNA and protein synthesis in 10-day-old rats was about 70% higher than in 30-day-old animals. In contrast, RNA synthesis did not decrease with age in all the regions examined.

Aging↗
PubMed1979

Mitochondrial DNA, RNA, and protein synthesis in different regions of developing rat brain.

In vivo and in vitro (tissue slices) incorporation of labeled precursors into DNA, RNA, and proteins was measured in mitochondria obtained from cerebral hemispheres, cerebellum, and brain stem of rats at different days of postnatal development. To compare the synthesis of macromolecules in mitochondria with that in other subcellular fractions, the incorporation of labeled precursors into DNA, RNA, and proteins extracted from nuclei and into RNA and proteins extracted from microsomes and cytoplasmic soluble fractions was also measured. The results obtained showed that the incorporation of [3H]thymidine into DNA and of [14C]leucine into proteins of nuclei and mitochondria from the various brain regions examined decreased during postnatal development; however, at 30 days of age the specific radioactivity of mitochondrial DNA was higher than that of nuclear DNA. [3H]Uridine incorporation into RNA decreased from 10 to 30 days of age in nuclei while in mitochondria it was quite similar at both ages. This result may be due to a faster turnover of mitochondrial RNA compared to that of mitochondrial DNA and proteins. The results obtained suggest an active biosynthesis of macromolecules in brain mitochondria and might indicate an intense biogenesis of these organelles in rat brain during postnatal development.

Animals↗
PubMed1976

Biosynthesis of DNA and RNA in neuronal and glial cells from various regions of developing rat brain.

Slices of cerebral hemispheres, brain stem, and cerebellum from rats 5-30 days old were used for in vitro incorporation of [methyl-3H]thymidine and [6-14C]orotic acid into DNA and RNA, respectively. The rates of DNA and RNA synthesis decreased markedly during development, with the most marked decrease observed for DNA. The different brain regions showed specific patterns of decline of DNA and RNA synthesis. Following incubation of slices, the tissues were fractionated to obtain fractions enriched in neuronal cells and in glial cells. In cerebellum, the granule neurons were separated from the Purkinje neurons. The glial:neuronal ratio of DNA specific activity was different in the three regions examined: in cortex it decreased from 6 at 10 days to 3 at 20-30 days; in brain stem it was 3 throughout 10-30 days; in the cerebellum (glia:granule neuron ratio) it was also 3 at 30 days but only 0.3 at 10 days. Concerning the RNA incorporation, small differences were found between neuronal and glial cells.

Age Factors↗
PubMed1976

Action of chloroquine on in vivo RNA and protein biosynthesis in the retina and the optic pathway of the rabbit.

The in vivo action of chloroquine on RNA and protein metabolism in the optic pathway of the albino or pigmented rabbit was examined. To study the acute effects, chloroquine in a dose of 500 mug was injected into the vitreous body of one eye. The following day the animals were injected into both eyes with [3H]uridine or [3H]leucine. At various time intervals following the isotope injections the retinal synthesis and the axonal transport of labelled RNA or protein was studied. The results showed no significant difference between the drug-treated and the control side with respect to synthesis and axonal transport of RNA or protein. Nor was any selective effect noticed on the synthesis of different RNA fractions from the retina. In long-term experiments chloroqune (100 mg/kg body weight) was administered via their drinking water 3 days a week for a period of 6 or 8 months. Following an intraocular injection of [3H]leucine no significant change in rapid axonal transport could be found in those chronically treated rabbits.

Animals↗