Developmental changes in the molecular weight of heterogeneous nuclear RNA.

The size distribution of heterogeneous nuclear RNA (hnRNA) in the sea urchin embryo changes markedly during early development. Measurement of cleavage (4.5 h) to late gastrula (40 h) hnRNA by sedimentation in aqueous and denaturing solvent indicates that in the stages tested cleavage (4.5 h) hnRNA is smallest and rotating blastula (13 h) hnRNA is largest. The molecular weight of cleavage hnRNA is calculated to be about one-third that of rotating blastula hnRNA. Sedimentation of early embryo hnRNA in denaturing solvent to disaggregate complexes demonstrated mean S values lower than those obtained in aqueous solvent.

Hydralazine-pyrimidine interactions may explain hydralazine-induced lupus erythematosus.

Hydralazine, the prototypic drug that induces systemic lupus erythematosus, reacts with thymidine and deoxycytidine. Analysis of a reaction mixture of therapeutic concentrations of hydralazine with labeled thymidine reveals at least four labeled products. At higher concentrations, hydralazine reacts with labeled deoxycytidine to form at least three labeled products. Formation of these products is markedly enhanced by exposure to ultraviolet light. The reaction of hydralazine with thymidine and deoxycytidine may be in part responsible for initiating drug-induced systemic lupus erythematosus.

Oligomeric sequences in the cytoplasmic RNA of sea urchin embryos.

Oligomeric stretches of adenylate and uridylate and polymeric segments of adenylate have been shown to exist in sea urchin embryo hnRNA. It is demonstrated here that at least some oligo(U)-enriched sequences are conserved in sea urchin cytoplasmic RNA, whereas apparently few, if any, oligo(A) sequences are so conserved.

Oligouridylate stretches in heterogeneous nuclear RNA.

Three classes of heterogeneous nuclear RNA (HnRNA) alpha, beta, and gamma, with different chemical and physical properties, can be identified in the early sea urchin embryo by hybridization with poly(U). The relative amounts of these classes vary as a function of embryonic development. It is demonstrated here that the adenyl-containing classes of HnRNA, alpha and beta, can be subfractionated by hybridization with poly(A)-agarose into species containing and lacking oligo(U)-enriched segments. These oligo(U) segments could not be detected in gamma HnRNA, which was previously shown to also lack adenylate segments. The relative proportions of these species undergo marked changes during development from early blastula (7 hr) to mesenchyme blastula (20 hr). I propose models to explain the possible effects of complementary sequences of adenylate and uridylate on the secondary structure of HnRNA, and speculate on the functional significance of such complexes.

Developmental shifts in the synthesis of heterogeneous nuclear RNA classes in the sea urchin embryo.

Three molecular classes with different properties can be distinguished in the heterogeneous nuclear RNA (HnRNA) of sea urchin embryos. The relative proportions of these classes, which we have previously designated alpha, beta and gamma HnRNA, undergo marked changes during development from morula to early gastrula. Such changes suggest the existence of more than a single HnRNA function, as well as specific roles for different HnRNA classes in embryonic development.

Properties of sea urchin embryo messenger RNA containing and lacking poly(A).

Various properties of nonhistone messenger RNA species containing poly(A), [+A]mRNA, and lacking poly(A), [-A]mRNA, are described: the rates of turnover of these mRNA classes are not significantly different, as indicated by their similar rates of entry into and decay from the cytoplasm; each mRNA class is essentially entirely transcribed from unique DNA sequences; the ratio of [+A] to [-A] nonhistone mRNA increases with increase in size of free polyribosome, although the average molecular weights of these mRNAs are similar in each polysomal size class. These results indicate that the [+A]mRNA species tend to be more fully loaded with ribosomes than the nonhistone [-A]mRNA species.

Phytohemagglutinin lymphocyte stimulation in children with recurrent urinary tract infections.

The delayed hypersensitivity (T cell) response of children with recurrent urinary tract infections, normal children, and children with other bacterial infections was measured by the ability of their lymphocytes to react to vitro to phytohemagglutinin. A comparison among these three groups demonstrated no differences in response. We conclude that the delayed hypersensitivity response is grossly normal in most children with recurrent urinary tract infections.