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Phyllosphere bacteria on ornamental plants were characterized based on their diversity and activity towards the removal of polycyclic aromatic hydrocarbons (PAHs), the major air pollutants in urban area. The amounts of PAH-degrading bacteria were about 1-10% of the total heterotrophic phyllosphere populations and consisted of diverse bacterial species such as Acinetobacter, Pseudomonas, Pseudoxanthomonas, Mycobacterium, and uncultured bacteria. Bacterial community structures analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis from each plant species showed distinct band patterns. The uniqueness of these phyllosphere bacterial communities was partly due to the variation in leaf morphology and chemical properties of ornamental plants. The PAH degradation activity of these bacteria was monitored in gas-tight systems containing sterilized or unsterilized leaves. The results indicated that phyllosphere bacteria on unsterilized leaves were able to enhance the activity of leaves for phenanthrene removal. When compared between plant species, phenanthrene removal efficiency corresponded to the size of phenanthrene-degrading bacteria. In addition, phyllosphere bacteria on Wrightia religiosa were able to reduce other PAHs such as acenaphthylene, acenaphthene, and fluorine in 60-ml glass vials and in a 14-l glass chamber. Thus, phyllosphere bacteria on ornamental plants may play an important role in natural attenuation of airborne PAHs in urban areas.

Preparations of the hemin-controlled repressor (HCR) from rabbit reticulocytes contain 3':5'-cyclic-AMP-independent protein kinase activity for the smallest subunit of the peptide initiation factor eIF-2 and for proteins of reticulocyte 40S ribosomal subunits. Binding of the ternary complex formed between Met-tRNAf, GTP, and eIF-2 to 40S ribosomal subunits is shown to be inhibited by phosphorylation of either the ribosomal subunits or eIF-2. The protein kinase activity responsible for phosphorylation of eIF-2 has been separated from the activity for phosphorylation of 40S ribosomal subunits and shown to independently block the same (8) and shown recently (9-11) that HCR acts as a protein kinase. All three papers (9)(10)(11) demonstrated that preparations of HCR promote cAMP-independent phosphorylation of the smallest subunit of eIF-2. However, in addition, we reported (9) that a highly purified preparation of HCR also phosphorylated certain proteins associated with reticulocyte 40S ribosomal subunits that had been washed with 0.5 M KCI.One or two ribosomal proteins of the reticulocyte 40S ribosomal subunits have been shown to be phosphorylated in vivo or in vitro (12)(13)(14). However, no biological function could be attributed to the phosphorylated or dephosphorylated state of the ribosomes.In the present paper initiation factor and GTP-dependent binding of Met-tRNAf to reticulocyte 40S has been studied as a partial reaction of peptide chain initiation. The methylene analogue of GTP, GMP-P(CH2)P, can substitute for GTP in this Abbreviations: HCR, hemin-controlled repressor; eIF-2, the initiation factor that forms a ternary complex with Met-tRNAf and GTP; GMP-P(CH2)P, guanosine 5'-(&3-y-methylene)triphosphate; AMP-P(CH2)P, adenosine 5'-(,--y-methylene)triphosphate. * (15) and the purification of eIF-2 (9) have been described.Reticulocyte ribosomal subunits were prepared by a modification of the procedure described by Falvey and Staehelin (16). About 150 mg of reticulocyte ribosomes was adjusted to a concentration of 10 mg/ml in a solution containing 0.5 M KC1/3 mM MgCl2/20 mM Tris-HCl, pH 7.5/1 mM 2-mercaptoethanol and kept at 40 for 30 min. Then the solution was layered on a 550 ml 15-30% (wt/vol)

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