Inovirus XacF1 (7325 nucleotides) is integrated into the genome of Xanthomonas citri pv. citri (Xcc) strains at the host dif site (attB) by the host XerC/D recombination system. The XacF1 attP sequence is located within the coding region of ORF12, a possible phage regulator. After integration, this open reading frame (ORF) is split into two pieces on the host genome. We examined dynamic integration/excision of XacF1 in Xcc strain MAFF 301080 and found that the integration started at 4 h postinfection (p.i.) and peaked at 12 h p.i. Thereafter, the ratio of integrated to free forms remained constant, suggesting equilibrium of integration and excision of XacF1 in the host genome. However, the integrated state became very unstable following a 5′‐deletion of ORF12 in XacF1, suggesting that ORF12 plays a key role in the integration cycle of XacF1 in Xcc strains.

The phosphorus nuclear magnetic resonance spectra of several condensed phosphates (polyphosphates) were measured in aqueous solutions. The NMR spectra generally consist of three peaks which correspond to the phosphorus atoms at the end and middle of the molecular chain and in orthophosphoric acid which is the final product of the hydrolysis. The chemical shift and, for some phosphates, spin-spin coupling constants were obtained. Both depend on pH of the solution. The chemical shifts for the end and middle phosphorus atoms depend also on the chain length of the molecule. The hydrolysis process of the phosphates can be traced by the observation of the time dependence of spectral line intensities. From this observation the rate constant of the hydrolysis is obtained for several phosphates. The values are comparable with those obtained by other methods.

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