All metazoan guts are in permanent contact with the microbial realm. However, understanding of the exact mechanisms by which the strength of gut immune responses is regulated to achieve gut-microbe mutualism is far from complete. Here we identify a signaling network composed of complex positive and negative mechanisms that controlled the expression and activity of dual oxidase (DUOX), which 'fine tuned' the production of microbicidal reactive oxygen species depending on whether the gut encountered infectious or commensal microbes. Genetic analyses demonstrated that negative and positive regulation of DUOX was required for normal host survival in response to colonization with commensal and infectious microbes, respectively. Thus, the coordinated regulation of DUOX enables the host to achieve gut-microbe homeostasis by efficiently combating infection while tolerating commensal microbes.

All metazoan guts are subjected to immunologically unique conditions in which an efficient antimicrobial system operates to eliminate pathogens while tolerating symbiotic commensal microbiota. However, the molecular mechanisms controlling this process are only partially understood. Here, we show that bacterial-derived uracil acts as a ligand for dual oxidase (DUOX)-dependent reactive oxygen species generation in Drosophila gut and that the uracil production in bacteria causes inflammation in the gut. The acute and controlled uracil-induced immune response is required for efficient elimination of bacteria, intestinal cell repair, and host survival during infection of nonresident species. Among resident gut microbiota, uracil production is absent in symbionts, allowing harmonious colonization without DUOX activation, whereas uracil release from opportunistic pathobionts provokes chronic inflammation. These results reveal that bacteria with distinct abilities to activate uracil-induced gut inflammation, in terms of intensity and duration, act as critical factors that determine homeostasis or pathogenesis in gut-microbe interactions.

Purpose -The purpose of this study is to analyze the structural relationship between empowerment, service training, service reward, job attitudes such as job satisfaction and organizational commitment, and customer-oriented prosocial behavior of employees. Design/methodology/approach -The research question is examined using a sample of Korean hotel employees. Structural equation analysis is used to test various research hypotheses and examine the extent to which job satisfaction and organizational commitment mediate the effect of empowerment, service training, and service reward on customer-oriented prosocial behavior. Findings -First, the greater the job satisfaction, the greater is the role-prescribed customer service of employees. Second, the greater the job satisfaction, the greater is the organizational commitment. Third, empowerment has a significant effect on organizational commitment and extra-role customer service. Fourth, service training has a significant effect on job satisfaction, but it has a negatively direct effect on organizational commitment. Fifth, service reward has a significant influence on job satisfaction and organizational commitment. Practical implications -Based on these empirical findings, employee management should be shifted from a transactional to a relationship-building orientation -the former being short-term goal-oriented and the latter long-term. Additionally, service organizations should evaluate employee lifetime value (ELV) as well as customer lifetime value (CLV). Research limitations/implications -There is a need to extend the results to a diverse range of service industries. Originality/value -This research explains that empowerment, service training, and service reward contribute to the evaluation of organizational commitment through the medium of job satisfaction.

Oxidative stress induced by reactive oxygen species (ROS) plays crucial roles in a wide range of physiological processes and is also implicated in various diseases, including cancer, chronic inflammatory diseases, and neurodegenerative disorders. Among the various ROS, hypochlorous acid (HOCl) plays as a powerful microbicidal agent in the innate immune system. The regulated production of microbicidal HOCl is required for the host to control the invading microbes. However, as a result of the highly reactive and diffusible nature of HOCl, its uncontrolled production may lead to an adverse effect on host physiology. Because of its biological importance, many efforts have been focused on developing selective fluorescent probes to image ROS. However, it is still challenging to design a fluorescent probe with exclusive selectivity toward a particular member of ROS. In the current work, we designed FBS as a new fluorescent HOCl probe which has high selectivity, sensitivity, and short response time in a broad range of pH. Compared with other sensors, the "dual-lock" structure of FBS has an advantage of eliminating interferences from other ROS/RNS. Importantly, we further showed that our HOCl probe could be applied for the in vivo imaging of physiological HOCl production in the mucosa of live animals. This probe provides a promising tool for the study of HOCl production.

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