RESUMO
In genetic engineering, gene expression is often modulated by replacements in promoter regions. Any deliberate intervention into the regulatory elements requires a subsequent evaluation based on analysis of reporter proteins. We have developed a new and rapid approach for characterization of promoter activity in which promoter strengths are determined by antibiotic resistance level. Values are expressed in comparison with those obtained from the reference promoter using the kanamycin resistance (aminoglycoside 3'-phosphotransferase) gene as a reporter. The new assay vector pSB1K0prom enables straightforward cloning of promoters or their subparts; therefore, mutations in different elements of the promoter region are easily introduced and analyzed. A series of promoters can be examined in parallel because no protein analysis is required other than determination of bacterial growth rates in the presence of increasing kanamycin concentrations. An internet application called PromCal for evaluation of experimental data has also been developed and is freely accessible at http://web.fkkt.uni-lj.si/biokemija/nskrlj/tools/PromCal.php.
Assuntos
Biologia Computacional/métodos , Engenharia Genética/métodos , Internet , Regiões Promotoras Genéticas/genética , Algoritmos , Sequência de Bases , Proliferação de Células , Eletroforese em Gel de Poliacrilamida , Escherichia coli/citologia , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Vetores Genéticos/genética , Viabilidade Microbiana , Dados de Sequência Molecular , Conformação de Ácido Nucleico , RNA Bacteriano/química , RNA Bacteriano/genética , Padrões de Referência , Fatores de TempoRESUMO
Ultrasonic vibration is employed to modify the friction of a finger pad in way that induces haptic sensations. A combination of intermittent contact and squeeze film levitation has been previously proposed as the most probable mechanism. In this paper, in order to understand the underlying principles that govern friction modulation by intermittent contact, numerical models based on finite element (FE) analysis and also a spring-Coulombic slider are developed. The physical input parameters for the FE model are optimized by measuring the contact phase shift between a finger pad and a vibrating plate. The spring-slider model assists in the interpretation of the FE model and leads to the identification of a dimensionless group that allows the calculated coefficient of friction to be approximately superimposed onto an exponential function of the dimensionless group. Thus, it is possible to rationalize the computed relative reduction in friction being (i) dependent on the vibrational amplitude, frequency, and the intrinsic coefficient of friction of the device, and the reciprocal of the exploration velocity, and (ii) independent of the applied normal force, and the shear and extensional elastic moduli of the finger skin provided that intermittent contact is sufficiently well developed. Experimental validation of the modelling using real and artificial fingertips will be reported in part 2 of this work, which supports the current modelling.
Assuntos
Dedos/fisiologia , Fricção , Modelos Biológicos , Tato , Ondas Ultrassônicas , Adulto , Análise de Elementos Finitos , Humanos , Masculino , Estimulação FísicaRESUMO
The aim of ongoing research is to develop a multi-scale multi-physics computational framework for modelling of human touch in order to provide understanding of fundamental biophysical mechanisms responsible for tactile sensation. The paper presents the development of a macro-scale global finite element model of the finger pad and calibration of applied material models against experimental results using inverse method. The developed macro model serves as a basis for down-scaling to micro finite element models of mechanoreceptors and further implementations and applications as a virtual tool in scientific or industrial applications related to neuroscience, haptics, prosthetics, virtual touch and packaging.