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정삼만 한국해양안보포럼 2018 한국해양안보논총 Vol.1 No.2
There is a limit to our ability to describe security realities with a dichotomy of peace and war. This has been evidenced by the facts that, even in peace time in place, Cream peninsula at the black sea was at the hands of Russia without declaring war and the South China Sea is about to be Chinese front yard. Likewise, other strategic objectives that could be achieved only through regular military attacks in war time are now being realized in the world even in the time of peace. This phenomena is the reason for the advent of the concept of gray zone strategy for its explanation. The very difficult issue with respect to the strategy is that it is not easy to explore appropriate counter measures against it. Considering the gradual and ambiguous characteristics of the strategy and our current maritime security situation, the strategy can bring about various maritime crisis on national level, thus being in need of in-depth analysis of and proactive measures against the strategy at the moment. Further thing to note is that the strategy is available for either the weak or the strong to be applied with a view to protecting and enhancing their national security interests, thus giving us many implications for our security.
정삼일,이명석,김수기,Barry L. Wanner 한국유전학회 2012 Genes & Genomics Vol.34 No.1
Polyphosphate kinase (ppk) synthesizes polyphosphate (polyPn+1) from polyPn and ATP and also catalyses its reversal reaction. In the process of identifying stimuli that affect E. coli ppk transcription, we show that purine limitation activates the E. coli ppk promoter by using a single-copy E. coli ppk promoter-lacZ (ppkPEc-lacZ) fusion and Ez-Tn5 random mutagenesis. The ppkPEc-lacZ expression was greatly induced (seven to eleven fold higher depending on the media) in purF mutant cells (e.g. cvpA::Ez-Tn5 and ΔpurF mutants). This behavior seems to result from the purine starvation because the ppkPEc-lacZ expression in the purF mutant cells was recovered to the level of wild-type cells by the addition of any type of purines (adenine, guanine, adenosine, and guanosine). The ppkPEc-lacZ expression was also increased in other pur mutants but not as much as in the purF mutant cells. Interestingly,the ppkPEc-lacZ expression was not changed in mutants with defective pyrimidine specific genes (e.g. ΔpyrE and ΔthiC). Transcription of four other bacterial ppk promoters also increased in the purF mutant cells. This data imply that purine deficiency seems to be a common and good inducer in bacterial ppk gene expression. Here, we present a novel report about the effect of purine biosynthesis on ppk gene expression in bacteria.