N1-S1/FdUrd Novikoff hepatoma cells, which lack thymidine kinase activity, are resistant to 5-fluorouracil (FUra) as well as 5-fluorodeoxyuridine (FdUrd), suggesting that the pathway, FUra leads to FdUrd leads to FdUMP, is utilized for the conversion of FUra to FdUMP. However, the inhibition of thymidylate synthetase activity, the presumed target of FdUMP, by 1 X 10(-4) M FUra in intact N1-S1 N...

Notch1 (N1) signaling induced by intrathymic Delta-like (DL) ligands is required for T cell lineage commitment as well as self-renewal during "β-selection" of TCRβ⁺CD4⁻CD8⁻ double negative 3 (DN3) T cell progenitors. However, over-expression of the N1 intracellular domain (ICN1) renders N1 activation ligand-independent and drives leukemic transformation during β-selection. DN3 progenitors also ...

The splicing of the c-src exon N1 is controlled by an intricate combination of positive and negative RNA elements. Most previous work on these sequences focused on intronic elements found upstream and downstream of exon N1. However, it was demonstrated that the 5' half of the N1 exon itself acts as a splicing enhancer in vivo. Here we examine the function of this regulatory element in vitro. We...

We have photoinactivated identified feeding interneurons known as N1 and N2 neurons. These are pattern-generating neurons that are active in the protraction of the radula and rasping phases, respectively, of the feeding cycle of the pond snail. The N1 or N2 feeding interneurons in the buccal ganglia were filled with the fluorescent dye 5(6)-carboxyfluorescein (5-CF) from the cut end of the nerv...

In this paper, we give a relatively simple though very efficient way to color the d-dimensional grid G(n1, n2, . . . , nd) (with ni vertices in each dimension 1 i d), for two different types of vertex colorings: (1) acyclic coloring of graphs, in which we color the vertices such that (i) no two neighbors are assigned the same color and (ii) for any two colors i and j , the subgraph induced by t...

The complete nucleotide sequence of the N1 neuraminidase gene of influenza virus A/USSR/90/77 was determined. Comparison of its predicted amino acid sequence with other N1 and N2 neuraminidases indicates that the N1 neuraminidases share most of the antigenic determinants mapped on the N2 neuraminidase but display at least one additional potentially antigenic region probably as a result of inter...

Stable cyclic adenosine 5'-diphosphate ribose (cADPR) analogues are chemical biology tools that can probe the Ca(2+) release mechanism and structure-activity relationships of this emerging potent second messenger. However, analogues with an intact "northern" ribose have been inaccessible due to the difficulty of generating the sensitive N1-ribosyl link. We report the first total synthesis of th...

Transmissible spongiform encephalopathies (TSE) are fatal neurodegenerative diseases of humans and animals. The underlying infectious agent, the prion, accumulates not only in the central nervous system (CNS) but also in secondary lymphoid organs. I will revisit the role of the immune system in peripheral prion pathogenesis, while focusing on the mechanisms by which extraneural and extralymphat...