Anomalous systemic arterial supply to the basal segments of the lung presenting with a murmur

A murmur was discovered on routine preschool physical examination of a 5 year and 7 month-old boy. A lower lobe lesion was detected by chest X-ray. Aortography demonstrated that a large systemic artery from the descending thoracic aorta supplied the basilar segments of the left lower lobe, which had no normal pulmonary arterial supply. A clinical diagnosis of intralobar sequestration of the lung was made, and left lower lobectomy was performed.

Autogenous regulation of RNA polymerase beta subunit synthesis in vitro

The effects of Escherichia coli RNA polymerase and its subassemblies and subunits on the in vitro synthesis of beta subunit directed by DNA from a lambda transducing phage lambdadrif+-6 were investigated. This phage carries the structural gene (rpoB) for beta subunit as well as the genes for EF (translation elongation factor)-Tu, some ribosomal proteins, and stable RNAs of the E. coli chromosome. Among the RNA polymerase proteins examined, the two oligomers, holoenzyme and alpha2beta complex, repressed the synthesis of only the beta subunit but not of other proteins encoded by the phage DNA. The results indicate that the expression of at least the betabeta' (rpoBC) operon is under autogenous regulation, in which both holoenzyme and alpha2beta complex function as regulatory molecules with repressor activity.

Comparative studies of RNA polymerase subunits from various bacteria

The molecular structure of RNA polymerases from Escherichia coli, Salmonella typhimurium, Salmonella anatum,serratia marcescens, Aerobacter aerogens, Proteus mirabilis and Bacillus subtilis were compared based on:i) inhibition of the enzyme activity by treatment with antibodies against E. coli RNA polymerase subunits;ii) analysis of antibody precipitates by sodium ododecyl sulfatepolyacrylamide gel electrophoresis; and iii) analysis of antibody precipitates by urea-isoelectrofocusing followed by sodium dodecyl sulfate-slab gel electrophoresis in the second dimension. All the bacterial RNA polymerases examined cross-react equally with anti-E. COLI HOLOPOLYMERASE BUT EXHIbit different extents of cross-reaction with antibodies against individual subunits. Except for B. subtilis RNA polymerase, the molecular weight and isoelectric point of the enzyme subunits are close to those of E. coli polymerase. However, minor difference were found at least within the resolution of the techniques employed:S. anatum polymerase has sigma subunit larger than E. coli sigma subunit; P. mirabilis enzyme has sigma subunit larger in size and more acidic in charge, and alpha subunit smaller and more basic than corresponding E. coli subunits. The electrophoretic map of B. subtilis enzyme subunits is completely different from that of E. coli enzyme.

Zinc is associated with the beta subunit of DNA-dependent RNA polymerase of Bacillus subtilis

The Bacillus subtilis DNA-dependent RNA polymerase holoenzyme and core enzyme each contain approximately two atoms of zinc per molecule. When the dissociated subunits of the enzyme are passed through a blue dextran-Sepharose affinity column, only the beta subunit binds to the column. The total zinc content of the enzyme is tightly bound to the beta subunit. Dialysis studies suggest that the two zinc ions differ in the strength of their association with the beta subunit. The presence of zinc in beta is consistent with several other lines of evidence which indicate that this subunit is dirrectly involved in phosphodiester bond formation. The blue dextran-Sepharose column procedure should be useful in future studies of the dissociation and reassociation of the enzyme since the method is rapid and provides excellent recovery of the beta subunit as well as the alpha and beta' subunits of the RNA polymerase.

Two polypeptides associated with the ribonucleic acid polymerase core of Bacillus subtilis during sporulation

The ribonucleic acid (RNA) polymerase from log-phase and sporulating cells of Bacillus subtilis was analyzed to determine whether any structural changes occurred during sporulation. The elution pattern of RNA polymerase from a deoxyribonucleic acid (DNA)-cellulose column revealed that sporulating cells at stages III and IV contained a new RNA polymerase fraction in addition to the vegetative holoenzyme (alpha2betabeta'sigma). Stage III cells contained the vegetative holoenzyme and a new enzyme with the composition alpha2betabeta'delta1; the molecular weight of delta1 was 28,000. Stage IV cells contained the vegetative holoenzyme, the delta1-containing enzyme, and another enzyme with the composition alpha2betabeta'delta2. The delta2 factor had a molecular weight of around 20,000. The delta-containing enzymes have a higher affinity for the DNA-cellulose column and a higher specific activity on various templates than vegetative holoenzyme. The simultaneous appearance of these enzymes with vegetative holoenzymes in sporulating cells is consistent with the data found previously with DNA-RNA hybridization studies, which showed that sporulating cells contained both vegetative and sporulation messenger RNAs.