pp. 68-76, 2017-01-31. 情報通信総合研究所
概要:The purpose of this study is to examine the impact of mobile technology on global economic development. For this, we used a global dataset that represents the proliferation of cellular phones and per capita GDP among 213 countries and regions. Then, we conducted the Granger causality test to investigate how the rapid spread of cellular phones relates to the growth of per capita GDP by regions, particularly in developing countries, emerging countries, and developed countries during the two decades since the 1990s. This study reveals two observations. First, in the 1990s, higher income led to an early diffusion of mobile technology among developed countries, although no causal relationship was visible in the emerging and developing countries. Second, the worldwide spread of the mobile technology in the 2000s began to promote the growth of per capita GDP not only in developed countries but also in emerging and developing countries such as African nations. Consequently, it seems reasonable to conclude that mobile technology, which prevailed only in the wealthier nations in the 1990s, has turned into a driving force of worldwide economic development in the 2000s.…続きを見る
Journal of Biological Chemistry.
pp. 1-, 2017-01-27.
概要:Timely initiation of replication in Escherichia coli requires functional regulation of the replication initiator, ATP-DnaA. The cellular level of ATP-DnaA increases just before initiation, after which its level decreases through hydrolysis of DnaA-bound ATP, yielding initiation-inactive ADP-DnaA. Previously, we reported a novel DnaA-ATP hydrolysis system involving the chromosomal locus datA, and named it datA-dependent DnaA-ATP hydrolysis (DDAH). The datA locus contains a binding site for a nucleoid-associating factor IHF and a cluster of three known DnaA-binding sites, which are important for DDAH. However, the mechanisms underlying the formation and regulation of the datA-IHF-DnaA complex remain unclear. We now demonstrate that a novel DnaA box within datA is essential for ATP-DnaA complex formation and DnaA-ATP hydrolysis. Specific DnaA residues, which are important for interaction with bound ATP and for head-to-tail inter-DnaA interaction, were also required for ATP-DnaA-specific oligomer formation on datA. Furthermore, we show that negative DNA supercoiling of datA stabilizes ATP-DnaA oligomers, and stimulates datA-IHF interaction and DnaA-ATP hydrolysis. Relaxation of DNA supercoiling by addition of novobiocin, a DNA gyrase inhibitor, inhibits datA function in cells. On the basis of these results, we propose a mechanistic model of datA-IHF-DnaA complex formation and DNA supercoiling-dependent regulation for DDAH.…続きを見る