Although nitric oxide (NO) is an important signaling molecule in bacteria and higher organisms, excessive intracellular NO is highly reactive and dangerous. Therefore, living cells need strict regulation systems for cellular NO homeostasis. Recently, we discovered that Streptomyces coelicolor A3(2) retains the nitrogen oxide cycle (NO→NO→NO→NO) and nitrite removal system. The nitrogen oxide cycle regulates cellular NO levels, thereby controlling secondary metabolism initiation (red-pigmented antibiotic, RED production) and morphological differentiation. Nitrite induces gene expression in neighboring cells, suggesting another role for this cycle as a producer of transmittable intercellular communication molecules. Here, we demonstrated that ammonium-producing nitrite reductase (NirBD) is involved in regulating NO homeostasis in S. coelicolor A3(2). NirBD was constitutively produced in culture independently of GlnR, a known transcriptional factor. NirBD cleared the accumulated nitrite from the medium. Nir deletion mutants showed increased NO-dependent gene expression at later culture stages, whereas the wild-type M145 showed decreased expression, suggesting that high NO concentration was maintained in the mutant. Moreover, the nir deletion mutant produced more RED than that produced by the wild-type M145. These results suggest that NO removal by NirBD is important to regulate NO homeostasis and to complete NO signaling in S. coelicolor.

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Two years ago, the rapid retirement of the baby boomer artisans in vast numbers threatened to erode the competitiveness of Japanese manufacturers (i.e., the 2007 problem). This study proposes a practical process for extracting skills and designing a training system, to accelerate the learning of skills in production fields by younger generations (the passing down of skills from generation to generation). The proposed process can be roughly divided into a description of a task, extraction of skill, and the design of a training system consisting of the following seven steps: structural arrangement of work, clarification of work condition and target, clarification of changes in quality, extraction of variation factor by worker, setting of a hypothesis, verification of the hypothesis and determination of an appropriate range of variation factors, and selection of the training facilities and design for the training system. The process of skill extraction and training design proposed in this study was applied to the handing down of skills in welding work for PVC boards at manufacturer of photo-developing machines. A verification experiment with 18 subjects was performed to verify the effects of the training system developed. The excellent training effects and high utility of the proposed process were verified.