Charge separation and recombination dynamics in Sn/Pb cocktail perovskite solar cells were clarified.

Norfloxacin (NFLX) caused induction of prophages VT1 and VT2 of enterohemorrhagic Escherichia coli O157 at subinhibitory concentrations. In time course experiments, we observed the following sequential events: upon induction, the phage genomes underwent multiplication; the amount of stx genes increased; and subsequently, large quantities of toxins VT1 and VT2 were produced. Further studies showed that the molecular mechanism of prophage induction is closely related to the RecA system since the prophage VT2 was not induced with NFLX in a recA mutant strain.

No abstract

The DNA-dependent protein kinase (DNA-PK) is a trimeric enzyme consisting of a 460-kDa catalytic subunit (DNA-PKcs) and a heterodimeric regulatory complex called Ku, which is comprised of 70 (Ku70) and 86 (Ku80) kDa subunits. Mutations that affect the expression of the catalytic or Ku80 subunits of DNA-PK disrupt both V(D)J recombination and DNA double-stranded break repair pathways. In this report, we show that two previously uncharacterized rodent cell lines that are defective in DNA double-stranded break repair express catalytically inactive DNA-PK. The DNA-PKcs from the DNA double-stranded break repair mutant cell lines IRS-20 and SX-9 assembles on double-stranded DNA but fails to function as a protein kinase. In addition to the kinase defect, the abundance of the DNA-PKcs from both of these cell lines is reduced relative to wild-type controls. These results suggest that the DNA-PKcs gene from each of these cell lines contains mutations that inactivate the enzymatic activity and the expression or stability of the gene product. These data further strengthen the hypothesis that DNA-PK-mediated protein phosphorylation is a necessary component of the DNA double-stranded break repair pathway.The rejoining of double-stranded DNA breaks induced by ionizing radiation or occurring as intermediates of V(D)J recombination is performed via a biochemical pathway that includes the DNA-dependent protein kinase holoenzyme. DNA-PK 1 is a trimeric complex consisting of a DNA-binding component made up of the 70 and 86 kd subunits of the Ku autoantigen (1, 2) and a catalytic subunit of approximately 460 kDa (3). Cells from the x-ray-sensitive complementation group (xrs)-7, which includes the severe combined immunodeficiency (scid) mouse and the Chinese hamster ovary (CHO) V3 cell line, exhibit reduced expression of the DNA-PKcs, lack measurable DNA-stimulated kinase activity, and are defective for DNA double-stranded break repair and V(D)J recombination (4 -6). Similarly, cells from the xrs-6 complementation group, which contain mutations that reduce the expression of the Ku80 subunit of DNA-PK, exhibit losses of Ku-specific DNA-ending binding activity (7-9) DNA-PK kinase activity (10) and are also defective for DNA double-stranded break repair and V(D)J recombination (11-13).Molecular analysis of these DNA-repair mutant cells indicates that DNA-PK is required for the rejoining of doublestranded DNA breaks, but the mechanism by which DNA-PK functions in this process has yet to be elucidated. DNA-PK is a serine and threonine protein kinase that is activated by doublestranded DNA containing single-stranded to double-stranded transitions, such as DNA-ends, nicks, gaps, and stem-loop structures (14). In vitro, the Ku and catalytic subunits of DNA-PK assemble in a DNA-dependent manner (15), and the DNA-bound holoenzyme preferentially phosphorylates substrates that are bound to the same DNA molecule (1, 16). DNA-PK has been shown to phosphorylate a broad range of proteins in vitro, most of which are DNA-binding proteins (17), includi...