RNA METABOLISM IN ISOLATED MOUSE BRAIN NUCLEI DURING EARLY POSTNATAL DEVELOPMENT

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Abstract
—RNA metabolism in isolated brain nuclei has been shown to be dramatically altered during early postnatal brain development. The present study involved an examination of the RNA products synthesized by nuclei at various stages of postnatal neural maturation. In all cases, the majority of the RNA appeared to be heterodisperse, non‐ribosomal and non‐tRNA in nature. In comparison to the RNA isolated from nuclei of neonatal tissue, the RNA from nuclei of 12‐day and 30‐day‐old mouse brain was found to be of smaller molecular weight. Despite the heterodisperse nature of these RNA molecules, the addition of α‐amanitin did not completely inhibit nuclear synthesis.An investigation of RNA synthesis in isolated neuronal and glial cell nuclei revealed that nucleic acid metabolism in these respective cell populations had different and distinct developmental patterns. Preparations enriched with glial cell nuclei were found to be most active at birth and then decreased in activity (3–4‐fold) during neural maturation. On the other hand, the rate of RNA synthesis in fractions enriched in neuronal cell nuclei was observed to increase dramatically in activity (4–5‐fold) until 14 days of age. From 14 days of age until adulthood, RNA synthetic activity remained essentially the same.