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( Robert J. Mitchell ),( Sung Kuk Lee ),( Tae Sung Kim ),( Cheol Min Ghim ) 생화학분자생물학회 2011 BMB Reports Vol.44 No.1
Inter-cellular communication via diffusible small molecules is a defining character not only of multicellular forms of life but also of single-celled organisms. A large number of bacterial genes are regulated by the change of chemical milieu mediated by the local population density of its own species or others. The cell density-dependent “autoinducer” molecules regulate the expression of those genes involved in genetic competence, biofilm formation and persistence, virulence, sporulation, bioluminescence, antibiotic production, and many others. Recent innovations in recombinant DNA technology and micro-/nano-fluidics systems render the genetic circuitry responsible for cell-to-cell communication feasible to and malleable via synthetic biological approaches. Here we review the current understanding of the molecular biology of bacterial intercellular communication and the novel experimental protocols and platforms used to investigate this phenomenon. A particular emphasis is given to the genetic regulatory circuits that provide the standard building blocks which constitute the syntax of the biochemical communication network. Thus, this review gives focus to the engineering principles necessary for rewiring bacterial chemo-communication for various applications, ranging from population-level gene expression control to the study of host-pathogen interactions. (BMB reports 2011; 44(1): 1-10)
Robert H. Koch,George W. Wolf,Anthony B. Hull,Nicholas M. Elias II,Bruce D. Holenstei,Richard J. Mitchell 한국우주과학회 2012 Journal of Astronomy and Space Sciences Vol.29 No.1
This report describes the inception, development and extensive use over 30 years of elliptical polarimeters at the University of Pennsylvania. The initial Mark I polarimeter design utilized oriented retarder plates and a calcite Foster-Clarke prism as the analyzer. The Mark I polarimeter was used on the Kitt Peak 0.9 m in 1969-70 to accomplish a survey of approximately 70 objects before the device was relocated to the 0.72 m reflector at the Flower and Cook Observatory. Successive generations of automation and improvements included the early-80’s optical redesign to utilize a photoelastic modulated wave plate and an Ithaco lock-in amplifier–the photoelastic modulating polarimeter. The final design in 2000 concluded with a fully remote operable device. The legacy of the polarimetric programs includes studies of close binaries, pulsating hot stars, and luminous late-type variables.
Mitchell, Robert J,Gu, Man Bock Humana Press ; Humana Press ; OCLC 2005 Applied biochemistry and biotechnology Vol.120 No.3
<P>The NagR protein is a response regulatory protein found in the bacterium Ralstonia sp. U2 that is involved in sensing for salicylic acid and the subsequent induction of the operon just upstream of its gene. The genes encoded for in this operon are involved in the degradation of salicylic acid. Escherichia coli strain RFM443 carrying a fusion of the Photorhabdus luminescens luxCDABE operon with the nagR gene and upstream region of the nagAa gene was constructed and characterized with respect to its optimum temperature, its response time and kinetics, and its ability to detect numerous benzoic acid derivatives. Although capable of detecting 0.5 mM salicylic acid at any temperature between 28 and 40 degrees C, this E. coli strain, labeled DNT5, showed its greatest relative activity at 30 degrees C, i.e., the temperature at which the largest induction was seen. Furthermore, experiments done with numerous benzoic acid derivatives found the NagR protein to be responsive to only a few of the compounds tested, including salicylic acid and 3-methyl salicylic acid, and acetyl salicylic acid was the strongest inducer. The lower limits of detection for these compounds with E. coli strain DNT5 were also established, with the native inducer, salicylic acid, giving the most sensitive response and detectable down to a concentration of about 2 microM. A second lux fusion plasmid was also constructed and transformed into an NahR background, Pseudomonas putida KCTC1768. Within this strain, NAGK-1768, the supplemental activity of the NahR protein on the nagAa promoter, was shown to extend both the range of chemicals detected and the sensitivity.</P>