A widespread pathway for substitution of adenine by diaminopurine in phage genomes.

DNA modifications vary in form and function but generally do not alter Watson-Crick base pairing. Diaminopurine (Z) is an exception because it completely replaces adenine and forms three hydrogen bonds with thymine in cyanophage S-2L genomic DNA. However, the biosynthesis, prevalence, and importance of Z genomes remain unexplored.

Inactivation of Three RG(S/T)GR Pentapeptide-Containing Negative Regulators of HetR Results in Lethal Differentiation of PCC 7120.

The filamentous cyanobacterium sp. PCC 7120 produces, during the differentiation of heterocysts, a short peptide PatS and a protein HetN, both containing an RGSGR pentapeptide essential for activity. Both act on the master regulator HetR to guide heterocyst pattern formation by controlling the binding of HetR to DNA and its turnover.

Ketyl-phenoxyl triplet radical pair in glycerol: Magnetic field effect and cage kinetics in terms of the two-state model.

The geminate recombination kinetics of the triplet pairs of neutral radicals formed as a result of hydrogen atom transfer from 4-methylphenol to 4,4'-dimethylbenzophenone in the triplet excited state was studied by laser flash photolysis in the temperature range of 263-323 K. The pair included aromatic ketyl and 4-methylphenoxyl radicals produced in a viscous (∼10 P) solution of the initial reagents in glycerol. The geminate recombination kinetics demonstrate a "tail" c(t) ∼ 1/t, with contribution of magnitude A, which increases with temperature.

Ancient association of cyanobacterial multicellularity with the regulator HetR and an RGSGR pentapeptide-containing protein (PatX).

One simple model to explain biological pattern postulates the existence of a stationary regulator of differentiation that positively affects its own expression, coupled with a diffusible suppressor of differentiation that inhibits the regulator's expression. The first has been identified in the filamentous, heterocyst-forming cyanobacterium, Anabaena PCC 7120 as the transcriptional regulator, HetR and the second as the small protein, PatS, which contains a critical RGSGR motif that binds to HetR. HetR is present in almost all filamentous cyanobacteria, but only a subset of heterocyst-forming strains carry proteins similar to PatS.

Photoinduced Reactions of Benzophenone in Biaxially Oriented Polypropylene.

The photoinduced reactions of benzophenone (B) in biaxially oriented polypropylene (BOPP) were studied with nanosecond laser photolysis (N laser, λ337.1 nm). The first observed transient was a triplet state B*.