Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress.

BACKGROUND: Salmonella Typhimurium is a Gram-negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella-containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin-encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post-transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post-transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S. Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild-type strain, suggesting that ompX mRNA is also regulated at a post-transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2-induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.

Occupational stress and coping mechanisms in crime scene personnel.

Background: Studies on occupational stress have shown that police officers (POs) are vulnerable to the effects of stress, demonstrated by increased risk of cardiometabolic diseases, which may be exacerbated by the use of maladaptive coping techniques. Although there is an abundance of research pertaining to stress in POs, little research has been done to assess a subset of law enforcement, crime scene personnel (CSP). Aims: To assess the stress levels, anxiety levels and coping mechanisms of CSP across the state of Texas. Methods: The Perceived Stress Scale (PSS), Police Stress Questionnaire (PSQ), and the Distress Thermometer were used to measure stress levels, the State-Trait Anxiety Inventory (STAI) was utilized to measure anxiety, and the Brief COPE questionnaire was used to measure coping mechanisms. Results: CSP (N = 76) surveyed reported both low stress and low anxiety for all measures used, with males reporting slightly higher stress and anxiety than females. Differences in coping mechanisms used by CSP were observed between males and females, but not between sworn officers and civilian workers. Female CSP used emotional support (P < 0.01), instrumental support (P < 0.05) and positive reframing (P < 0.05) as a coping mechanism significantly more often than males. Conclusions: The results suggest that adaptive coping mechanisms should be emphasized by those supervising CSP. With little research available on CSP, further evaluation of the type of stressors experienced by these members of law enforcement is warranted.

Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress

BACKGROUND: Salmonella Typhimurium is a Gram negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S . Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild type strain, suggesting that ompX mRNA is also regulated at a post transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2 induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.