Comparative Transcriptome Analysis of Bacillus subtilis Responding to Dissolved Oxygen in Adenosine Fermentation

Dissolved oxygen (DO) is an important factor for adenosine fermentation. Our previous experiments have shown that low oxygen supply in the growth period was optimal for high adenosine yield. Herein, to better understand the link between oxygen supply and adenosine productivity in B. subtilis (ATCC21616), we sought to systematically explore the effect of DO on genetic regulation and metabolism through transcriptome analysis. The microarrays representing 4,106 genes were used to study temporal transcript profiles of B. subtilis fermentation in response to high oxygen supply (agitation 700 r/min) and low oxygen supply (agitation 450 r/min). The transcriptome data analysis revealed that low oxygen supply has three major effects on metabolism: enhance carbon metabolism (glucose metabolism, pyruvate metabolism and carbon overflow), inhibit degradation of nitrogen sources (glutamate family amino acids and xanthine) and purine synthesis. Inhibition of xanthine degradation was the reason that low oxygen supply enhanced adenosine production. These provide us with potential targets, which can be modified to achieve higher adenosine yield. Expression of genes involved in energy, cell type differentiation, protein synthesis was also influenced by oxygen supply. These results provided new insights into the relationship between oxygen supply and metabolism

Metabolic and Transcriptional Response to Cofactor Perturbations in Escherichia coli

Metabolic cofactors such as NADH and ATP play important roles in a large number of cellular reactions, and it is of great interest to dissect the role of these cofactors in different aspects of metabolism. Toward this goal, we overexpressed NADH oxidase and the soluble F1-ATPase in Escherichia coli to lower the level of NADH and ATP, respectively. We used a global interaction network, comprising of protein interactions, transcriptional regulation, and metabolic networks, to integrate data from transcription profiles, metabolic fluxes, and the metabolite levels. We identified high-scoring networks for the two strains. The results revealed a smaller, but denser network for perturbations of ATP level, compared with that of NADH level. The action of many global transcription factors such as ArcA, Fnr, CRP, and IHF commonly involved both NADH and ATP, whereas others responded to either ATP or NADH. Overexpressing NADH oxidase invokes response in widespread aspects of metabolism involving the redox cofactors (NADH and NADPH), whereas ATPase has a more focused response to restore ATP level by enhancing proton translocation mechanisms and repressing biosynthesis. Interestingly, NADPH played a key role in restoring redox homeostasis through the concerted activity of isocitrate dehydrogenase and UdhA transhydrogenase. We present a reconciled network of regulation that illustrates the overlapping and distinct aspects of metabolism controlled by NADH and ATP. Our study contributes to the general understanding of redox and energy metabolism and should help in developing metabolic engineering strategies in E. coli

The effects of workplace bullying on sleep well-being: The mediating role of rumination

There is evidence of the effects of workplace bullying on victims who may manifest symptoms of depression, anxiety, burnout, somatization, and posttraumatic stress; however, few studies have examined the impact of workplace bullying on sleep. The purpose of the present study was to examine the relationship between workplace bullying and sleep well-being and how rumination mediates this relationship. A total of 1,046 employed subjects participated in this cross-sectional design study. To examine the hypotheses, the structural equations model was used via SMART-PLS program. In addition to examine the relationship between workplace bullying and sleep well-being, several mediation analyzes were conducted to examine the mediating role of work-related rumination in the relationship of workplace bullying and sleep well-being. Workplace bullying was inversely and significantly correlated with sleep well-being. The affective rumination was inversely and significantly correlated with sleep well-being, and detachment also correlated significantly, but positively with sleep well-being. However, the problem-solving dimension did not correlate significantly with sleep well-being. Mediation analyzes suggest that affective rumination and detachment mediate the relationship between workplace bullying and sleep well-being. The results of the present study have both theoretical and practical implications, among which we can mention that sleep well-being is an important factor in the recovery of people and workplace bullying as well as rumination seem to affect it, it brings a challenge for the psychologists in occupational health context and human resources practitioners in the management of this phenomenon in organizations.