Growth of measles and subacute sclerosing panencephalitis viruses in human neural cell lines

Growth of cell-free subacute sclerosing panencephalitis (SSPE) virus was compared with that of measles virus in three human neural cell lines; neuroblastoma, oligodendroglioma, and glioblastoma. The Edmonston strain of measles virus replicated in these neural cells as efficiently as in Vero cells. In contrast, the growth of the Mantooth strain of SSPE virus was suppressed moderately in neuroblastoma cells and markedly in oligodendroglioma and glioblastoma cells in spite of the induction of apparent cytopathic effects in these cells. Virus adsorption, defective interfering particles, interferon, and temperature sensitivity were not responsible for this low yield of SSPE virus in neural cell lines. Synthesis of viral proteins of SSPE virus was slower than that of measles virus in oligodendroglioma and glioblastoma cells. These results suggest that the slow rate of synthesis of viral proteins may be relevant to the low yield of SSPE virus in neural cells.     

Androgenic stimulation of endocytosis, amino acid and hexose transport in mouse kidney cortex involves increased calcium fluxes

Testosterone was previously shown to induce an early (less than 1 min) receptor-dependent stimulation of endocytosis, hexose and amino acid transport in mouse kidney cortex (Koenig, H., Goldstone, A. and Lu, C.Y. (1982) Biochem. Biophys. Res. Commun. 104, 165-172). Testosterone (10(-8) M) has now been found to stimulate rapidly (less than 30 s) the influx and efflux of 45Ca2+ in cortex slices. Testosterone also decreased mitochondrial 45Ca and augmented soluble 45Ca, indicating a mobilization of intracellular calcium. Incubation of cortex slices in calcium-free medium without or with 2.5 mM EGTA decreased basal endocytosis, hexose and amino acid transport and blocked the hormonal response. 100 microM verapamil blocked the hormonal response without affecting basal transport. The calcium ionophore A23187 rapidly stimulated endocytosis, hexose and amino acid transport. These data indicate that androgenic stimulation of membrane transport functions involves an increased influx of extracellular calcium and a mobilization of intracellular calcium. Increased cytosolic Ca2+ is probably the regulatory signal for these transport processes.     

Cleavage of dT8 and dT8 phosphorothioyl analogues by Escherichia coli DNA topoisomerase I: product and rate analysis

Escherichia coli DNA topoisomerase I catalyzes the cleavage of short, single-stranded oligodeoxynucleotides with dT8 as the shortest cleavable oligo(thymidylic acid). The 5'-32P-labeled products formed from the cleavage of [5'-32P]dT8 are dT5, dT4, and dT3 with over 70% of the substrate cleaved to dT4. Mg(II) ions affect this product distribution by increasing the percentage of dT4 formed. The substitution of a sulfur atom for a nonbridging oxygen atom in a phosphodiester linkage yields oligodeoxynucleotide phosphorothioyl (PS) analogues. The epimers of the analogues were separated, and the position and stereochemistry of the phosphorothiodiester bond were determined. Topoisomerase I is stereospecific in its reactivity toward these analogues. With the oligodeoxynucleotide PS analogue substrates, the rate of cleavage, the stereospecificity, and the product distribution depend upon the position and the stereochemistry of the phosphorothiodiester linkage.     

A statistical method for correlating tRNA sequence with amino acid specificity.

A statistical method for finding the nucleotide positions in tRNA sequences that correlate with amino acid specificity has been developed. The procedure involves finding the subset of nucleotide positions and groups of positions where the marginal density of one amino acid tRNA class does not overlap that of any other amino acid class. The procedure is an application of a statistical method known as the Expectation Maximization algorithm.     

Coordinate regulation of ribosomal protein mRNA level in regenerating rat liver. Study with the corresponding mouse cloned cDNAs.

Cloned mouse ribosomal protein (rp) cDNAs exhibit extensive homology with the corresponding rat sequences. The size of the rp-mRNAs and complexity of the rp-genes are very similar in the two species. Using the mouse rp-recombinant DNAs we find that the relative abundance of rat L7, L13, L18, L30, L32/33 and S16 mRNAs increases after partial hepatectomy. Their maximal level is about twice that of normal rat liver, and is achieved 12-18 h after the operation, while the relative abundance of albumin mRNA decreases to half the normal values 12 h after partial hepatectomy. This concomitant increase in the relative content of these rp-mRNAs indicates coordinate regulation of their level in the rat. The dissimilar behavior of L10 and L19 rp-mRNA suggests additional control mechanisms of rp-mRNA levels in the regenerating rat liver.