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Nucleic Acids Res ; 48(15): 8490-8508, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32687193


Several functions have been proposed for the Escherichia coli DNA polymerase IV (pol IV). Although much research has focused on a potential role for pol IV in assisting pol III replisomes in the bypass of lesions, pol IV is rarely found at the replication fork in vivo. Pol IV is expressed at increased levels in E. coli cells exposed to exogenous DNA damaging agents, including many commonly used antibiotics. Here we present live-cell single-molecule microscopy measurements indicating that double-strand breaks induced by antibiotics strongly stimulate pol IV activity. Exposure to the antibiotics ciprofloxacin and trimethoprim leads to the formation of double strand breaks in E. coli cells. RecA and pol IV foci increase after treatment and exhibit strong colocalization. The induction of the SOS response, the appearance of RecA foci, the appearance of pol IV foci and RecA-pol IV colocalization are all dependent on RecB function. The positioning of pol IV foci likely reflects a physical interaction with the RecA* nucleoprotein filaments that has been detected previously in vitro. Our observations provide an in vivo substantiation of a direct role for pol IV in double strand break repair in cells treated with double strand break-inducing antibiotics.

Subst Use Misuse ; 53(3): 508-520, 2018 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-28857646


BACKGROUND: The co-occurence of posttraumatic stress (PTS) and risky drinking has been demonstrated in diverse populations, including college students. However, the mechanisms underlying this co-occurrence, as well as the protective factors that may reduce risky drinking among trauma-exposed college students have yet to be fully understood in the literature. OBJECTIVES: The present study builds upon self-regulation theories and previous empirical work to determine whether the effects of PTS and coping flexibility on risky drinking were mediated by delay of gratification among trauma-exposed college students. In addition, the potential moderating effect of gender on these relationships was examined. METHODS: Participants included 624 trauma-exposed college students (68.4% female) attending a public university in the southeast region of the United States. Data were collected through an online survey. The hypothesized model was examined using a multigroup structural equation modeling approach. RESULTS: As hypothesized, PTS had a significant, positive indirect effect on risky drinking through delay of gratification; however, the effect of PTS on delay of gratification was stronger for males than for females. Results also indicated that the indirect effect of coping flexibility on risky drinking through delay of gratification was significant and negative for males and females. Conclusions/Importance: The findings of this study suggest that delay of gratification might be an important mechanism underlying the co-occurrence of PTS and risky drinking. In addition, our results highlight the potential benefits of coping flexibility for college students coping with PTS.

Adaptação Psicológica , Consumo de Bebidas Alcoólicas/psicologia , Desvalorização pelo Atraso , Assunção de Riscos , Transtornos de Estresse Pós-Traumáticos/psicologia , Estudantes/psicologia , Universidades , Feminino , Humanos , Acontecimentos que Mudam a Vida , Masculino , Fatores de Proteção , Fatores Sexuais , Adulto Jovem
ACS Appl Mater Interfaces ; 9(32): 27290-27297, 2017 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-28745040


The parallel-plate capacitor equation is widely used in contemporary material research for nanoscale applications and nanoelectronics. To apply this equation, flat and smooth electrodes are assumed for a capacitor. This essential assumption is often violated for thin-film capacitors because the formation of nanoscale roughness at the electrode interface is very probable for thin films grown via common deposition methods. In this work, we experimentally and theoretically show that the electrical capacitance of thin-film capacitors with realistic interface roughness is significantly larger than the value predicted by the parallel-plate capacitor equation. The degree of the deviation depends on the strength of the roughness, which is described by three roughness parameters for a self-affine fractal surface. By applying an extended parallel-plate capacitor equation that includes the roughness parameters of the electrode, we are able to calculate the excess capacitance of the electrode with weak roughness. Moreover, we introduce the roughness parameter limits for which the simple parallel-plate capacitor equation is sufficiently accurate for capacitors with one rough electrode. Our results imply that the interface roughness beyond the proposed limits cannot be dismissed unless the independence of the capacitance from the interface roughness is experimentally demonstrated. The practical protocols suggested in our work for the reliable use of the parallel-plate capacitor equation can be applied as general guidelines in various fields of interest.