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Biomedical subjects

M W Nirenberg

Publications and source records attributed to M W Nirenberg.

14 recordsLinked to original sources
PubMed1974

Selection for neuroblastoma cells that synthesize certain transmitters.

A selection procedure was devised for neurons and related cells that depends upon the ability of the cells to synthesize certain amine neurotransmitters. The rationale for selection is that tyrosine is an essential amino acid for most mammalian cells and that three enzymes from mammalian sources can catalyze the synthesis of tyrosine: phenylalanine hydroxylase (EC 1.14.16.1), tyrosine hydroxylase (EC 1.14.16.2), and tryptophan hydroxylase (EC 1.14.16.4). Tyrosine hydroxylase is found predominantly in adrenergic neurons and related cells that synthesize dopamine, norepinephrine, and epinephrine, and tryptophan hydroxylase in cells synthesizing serotonin or melatonin. Only 1 out of 70,000 uncloned mouse neuroblastoma cells grew well in the absence of tyrosine. Approximately 50% of the cell lines obtained by selection had tyrosine hydroxylase activity. This selection procedure thus provides a simple means of obtaining cell lines of neural origin on the basis of their ability to synthesize putative transmitters.

Animals↗
PubMed1973

Development of acetylcholine receptor clusters on cultured muscle cells.

Clusters of acetylcholine receptors were formed in the absence of neurons during the development of cultured chick-embryo skeletal muscle cells. The average concentration of receptors in clusters was estimated to be 9000 per mum(2). At other regions of the cell, receptor concentration was 900 per mum(2). The possibility that receptor clusters may participate in synapse formation is suggested.

Animals↗
PubMed1972

Acetylcholine receptors of muscle grown in vitro.

[(125)I]Monoiodo- and [(125)I]diiodo-alpha-bungarotoxin were synthesized and shown to bind specifically to the acetylcholine receptor of cultured embryonic chick- and rat-muscle cells. The pharmacologic properties of the receptor of cultured embryonic chick muscle resembled those of the nicotinic acetylcholine receptor of adult vertebrate muscle. Autoradiography of muscle cells labeled with toxin showed that acetylcholine receptors were distributed over the entire cell surface. In addition, discrete areas with a high receptor concentration were found.

Acetylcholine↗
PubMed1970

Regulation of axon formation by clonal lines of a neural tumor.

Clonal lines of neuroblastoma cells were found to extend or retract axons depending upon the concentration of serum. Neurite extension was not inhibited by cycloheximide but was sensitive to colchicine or vinblastine, suggesting that neurite formation is dependent upon the assembly of microtubules or neurofilaments from preformed protein subunits.

Axons↗