Staphylococcus aureus cells of strain 8325 (N) are competent for phage deoxyribonucleic acid (DNA) when harvested in the early exponential growth phase. Phenotypic expression of the competence requires divalent cations, and calcium ions are most effective. Treatment of phage DNA with deoxyribonuclease completely destroys infectivity and heat-denaturated DNA is not infectious. The highest freque...

Sedimentation and electron microscopic studies have provided no evidence for the presence of circular DNA (deoxyribonucleic acid) in chloroplasts from wheat leaves. Electron microscopy of osmotically disrupted chloroplasts has revealed the presence of linear duplex filaments, some with a tertiary helicoidal configuration and possibly monostranded filaments. None of these structures was observed...

1. The pH optimum, ionic requirement and heat-stability of a purified liver nuclease have been examined with RNA and denatured DNA as substrates. 2. The enzyme attacked DNA and RNA in an endonucleolytic manner, forming oligonucleotides terminated by 5'-phosphate groups. No clear specificity was found with respect to the bases at the site of cleavage. 3. Comparison of the results obtained with R...

Clinical isolates (869) and stock cultures (35) of Enterobacteriaceae were tested in parallel with the Minitek and conventional systems. The Minitek correctly identified 822 of 904 cultures. When a deoxyribonuclease plate was inoculated along with the Minitek, it was possible to speciate Enterobacteriaceae within 24 h. False-positive hydrogen sulfide reactions were the major fault with this sys...

Two lines of evidence for the existence of DNA in the pellicle of Paramecium are presented: fluorescence staining and autoradiography. The latter shows deoxyribonuclease-sensitive incorporation of tritiated thymidine in or near the kineties. Fluorescence microscopy permits the localization of DNA at the site of kinetosomes. The possibility that the DNA is not native to the pellicle but introduc...

Dehydroheliotridine, a major pyrrolic metabolite of heliotridine-based pyrrolizidine alkaloids, interacted with both native and heat-denatured DNA in vitro under mildly acid conditions to form a soluble non-diffusible complex as shown by spectral data. The complex formed with heat-denatured DNA was more resistant than heat-denatured DNA alone to the combined action of deoxyribonuclease and phos...