Carol H. Letendre

The biosynthesis of phosphorylated tyrosine hydroxylase by organ cultures of rat adrenal medulla and superior cervical ganglia

Abstract Tyrosine hydroxylase has been synthesized in organ cultures of rat adrenal medulla and superior cervical ganglia and isolated by immunoprecipitation followed by SDS-polyacrylamide gel electrophoresis. When the cultures were grown in radioactive phosphate the tyrosine hydroxylase contained radioactivity. Superior cervical ganglia from animals injected with nerve growth factor made more tyrosine hydroxylase and proportionately more phosphate was incorporated into the enzyme than in ganglia from control animals.

chapter 12 Rna Sequence Complexity in Central Nervous System Development and Plasticity

Publisher Summary Several lines of research with brain RNA have developed since the initial RNA complexity studies began. This chapter assesses the present understanding of brain transcription, with reference to hybridization studies with nonrepetitive and complementary DNA. Recent advances in the understanding of RNA processing and its relation to brain RNA are reviewed. The chapter discusses the studies showing effects of development, aging, and sensory-environmental factors on gene expression. The conclusions of studies on the RNAs of clonal cell lines of neural origin are presented, and the implications of these data for characterization of the transcriptional pattern in brain are also discussed. Unlike studies focusing on the expression of individual gene products in brain or on the specific physiological properties of nerve cells, studies on the expression of nonrepetitive DNA are able to define the total transcriptional or translational response of the brain to such key neurobiological events as differentiation and synapse formation.

BRAIN AMINO ACIDS

Publisher Summary This chapter focuses on the distribution and content of amino acids in brain. The transport of an amino acid into and out of the brain, the speed of its various metabolic conversions, and the rate of its incorporation into protein determine the concentration of that particular amino acid found free in the brain. The total free amino acid nitrogen of the brain is about six times higher than the amino acid nitrogen concentration of plasma, and the individual amino acids are at least twice as concentrated in the brain as in the plasma. Much of the amino acid nutrition of the brain is provided by the blood stream. Experiments done both in vivo and with brain slices have led to an understanding of the number and the specificities of the active transport systems of brain. It is known that there are at least seven different systems for amino acid uptake: acidic amino acids, γ-aminobutyric acid and other γ-amino acids, small neutral amino acids, amido amino acids, small basic amino acids, large neutral amino acids, and large basic amino acids.

Sequence complexity and frequency distribution of poly(A)-containing messenger RNA sequences from the glioma cell line (C6.

OUR CONCEPT of gene transcription has undergone important changes over the past few years, particularly as a result of recent data obtained with recombinant DNA technology (GARAPIN et a/., 1978; LAI et al., 1978). Recent work on nuclear RNA suggests that processing of a nuclear RNA molecule yields a mature messenger RNA (mRNA) molecule (TILGHMAN et al., 1978). Since the most extensive gene expression in any mammalian organ occurs in the brain, where as much as 32% of all potential genes may be expressed in nuclear RNA (BANTLE & HAHN, 1976; BROWN & CHURCH, 1972; CHIKARAISHI e t al.. 1978; GROUSE et al., 1972, 1978; HAHN & LAIRD, 1971), it follows that if all mRNAs arise from nuclear RNA processing, 32% of all possible mRNAs would also be expressed in brain. The mRNA complexity of brain appears to be widely apportioned among different cell types. Our recent calculations showed (GROUSE et al., 1978) that rat brain can be divided into about 7000 different cell types on the basis of RNA sequence complexity and frequency data. Each of these cell types would be characterized by the expression of 1C-20 specific genes. Little is known, however, about the relative RNA complexities of the neuronal and glial elements of brain. In the absence of highly purified diploid cell types from brain, minimal deviation tumor cells of the nervous system were studied. Our recent data (SCHRIER et al., 1978) on the RNAs of mouse neuroblastoma provide a model of neuronal cell transcription. The nuclear RNA of the neuroblastoma clone S20:DB6 bad a sequence complexity of 9 x lo7 nucleotides, while the complexity of the poly(A)-containing mRNA was 4.4 x 10’ nucleotides. For comparison with these data, the subject of this communication will be the results of our analysis of the complexities and abundances of poly(A) mRNA species in a glial cell line, the cloned rat astrocytoma cell line C6. The cell line C6 has frequently been used in neurobiological studies as a glial cell model. It has been shown to respond to hydrocortisone (BENNETT et al., 1977) and /J-adrenergic agonists (FRANKLIN & TWOSE, 1977; GILMAN & NIRENBERG, 1971), and to have regulatable synthesis of the S-100 protein (LABOURDETTE et a/., 1977), uptake mechanisms for putative neurotransmitters (SCHRIER & THOMPSON, 1974) and specific cell adhesive properties (SANTALA & GLASER, 1977). We used the diploid C6Bul clone of C6, which we obtained from Dr. MARSHALL NWENBERG. This cell line