An assessment of the antisense properties of RNase H-competent and steric-blocking oligomers.

The antisense activity and gene specificity of two classes of oligonucleotides (ONs) were directly compared in a highly controlled assay. One class of ONs has been proposed to act by targeting the degradation of specific RNAs through an RNase H-mediated mechanism and consists of C-5 propynyl pyrimidine phosphorothioate ONs (propyne-S-ON). The second class of antisense agents has been proposed to function by sterically blocking target RNA formation, transport or translation and includes sugar modified (2'-O-allyl) ONs and peptide nucleic acids (PNAs).

Distinct spatial localization of specific mRNAs in cultured sympathetic neurons.

We examined the subcellular distribution of specific mRNAs in cultured sympathetic neurons. Under appropriate conditions, sympathetic neurons extend both axons and dendrites that are distinguishable by light microscopic and immunocytochemical criteria. In situ hybridization revealed a differential localization of mRNA within dendrites.

Age-dependent changes in the capacity of rat sympathetic neurons to form dendrites in tissue culture.

We compared the ability of prenatal and postnatal rat sympathetic neurons to form dendrites in tissue culture. Dendrites were distinguished from axons by light microscopic criteria after intracellular dye injection and by differential immunostaining with antibodies to microtubule-associated protein-2 and to both non-phosphorylated and phosphorylated forms of the M and H neurofilament subunits. When maintained in the absence of serum and non-neuronal cells, most (72%) prenatal neurons were unipolar and had only an axon.

Morphological differentiation of embryonic rat sympathetic neurons in tissue culture. II. Serum promotes dendritic growth.

In the preceding paper, we reported that embryonic rat sympathetic neurons formed axons, but not dendrites, when they were maintained in the absence of serum and nonneuronal cells. To assess the effects of serum-derived factors on cellular morphology, cultures were initially maintained in serum-free medium while nonneuronal cells were eliminated. Subsequently some cultures were chronically exposed either to fetal calf serum (10%) or to a high-molecular-weight ammonium sulfate fraction of serum (P40 material, 500 micrograms/ml).

Morphological differentiation of embryonic rat sympathetic neurons in tissue culture. I. Conditions under which neurons form axons but not dendrites.

We have examined the morphology of fetal rat sympathetic neurons grown in serum-free medium in the absence of nonneuronal cells. Because cell density can affect phenotypic expression in vitro, the morphological analysis was subdivided into the study of isolated neurons (neurons whose somata were at least 150 micron from their nearest neighbor) and of more highly aggregated neurons. When isolated neurons were injected with intracellular markers, it was found that most (79%) had a single process emanating from their somata and that this unipolar state persisted for at least 8 weeks in vitro.

Excretion and metabolism of nicotinic acid by the avian kidney.

The renal tubular transport and metabolism of nicotinic acid (NA) were investigated using the Sperber technique in unanesthetized hens. Infusion of [14C]NA into the avian renal portal circulation at 10(-10) mol/kg/min revealed that the 14C label was actively transported into urine at a rate 74% that of simultaneously infused tetraethylammonium. Increases in NA infusion rates enhanced 14C label transport so that it eventually equalled the excretion rate of tetraethylammonium.

Avian sarcoma virus gag precursor polypeptide is not processed in mammalian cells.

We studied intracellular avian gag proteins (internal structural proteins of virions) in several mammalian cell lines transformed by Rous sarcoma virus. All lines examined contain gag antigens as determined by radioimmune assay. We used the techniques of protein blotting from polyacrylamide gels, which detects nanogram quantities of viral protein, to investigate the size of intracellular viral polypeptides.