Processes for decoding the genetic information in cells, including transcription, replication, recombi- nation and repair, involve the deformation of DNA from its equilibrium structures such as bending, stretching, tw...Processes for decoding the genetic information in cells, including transcription, replication, recombi- nation and repair, involve the deformation of DNA from its equilibrium structures such as bending, stretching, twisting, and unzipping of the double helix. Single-molecule manipulation techniques have made it possible to control DNA conformation and simultaneously detect the induced changes, revealing a rich variety of mechanically-induced conformational changes and thermodynamic states. These single-molecule techniques helped us to reveal the physics of DNA and the processes involved in the passing on of the genetic code.展开更多
The degree and characteristics of physical degradation of macro-DNA molecules by common laboratory manipulations are reported. With linearized lambda-phage viral DNA as the model DNA, fragmentation of macro-DNA by var...The degree and characteristics of physical degradation of macro-DNA molecules by common laboratory manipulations are reported. With linearized lambda-phage viral DNA as the model DNA, fragmentation of macro-DNA by various indispensable laboratory manipulations were investigated using a high sensitivity flow cytometric setup. Investigated manipulations included pipetting, vortexing, rocking, freeze-thawing, ultrasonication and ultrafiltration. “Exhaustive counting” of the intact lambda DNA molecules following such manipulations enabled a quantitative assessment of the resulting fragmentation, which also revealed the type of degradation reflected in the fragmentation patterns. The use of high sensitivity flow cytometry was especially suited to investigate the degradation of dilute DNA solutions that may not be suitable for analysis using traditional methods. Notable findings of this study included: the boarderline-size of DNA chains in terms of susceptibility to shear stresses by such manipulations;discernable instability of nicked DNAs;shattering-fragmentation of DNAs by freeze-thawing or ultrasonication;effectiveness of some protection media;marked “self-protection effect” of concentrated DNA solutions. These findings support and refine our traditional knowledge on how to maintain the physical integrity of macro-DNA molecules against inevitable laboratory manipulations.展开更多
文摘Processes for decoding the genetic information in cells, including transcription, replication, recombi- nation and repair, involve the deformation of DNA from its equilibrium structures such as bending, stretching, twisting, and unzipping of the double helix. Single-molecule manipulation techniques have made it possible to control DNA conformation and simultaneously detect the induced changes, revealing a rich variety of mechanically-induced conformational changes and thermodynamic states. These single-molecule techniques helped us to reveal the physics of DNA and the processes involved in the passing on of the genetic code.
文摘The degree and characteristics of physical degradation of macro-DNA molecules by common laboratory manipulations are reported. With linearized lambda-phage viral DNA as the model DNA, fragmentation of macro-DNA by various indispensable laboratory manipulations were investigated using a high sensitivity flow cytometric setup. Investigated manipulations included pipetting, vortexing, rocking, freeze-thawing, ultrasonication and ultrafiltration. “Exhaustive counting” of the intact lambda DNA molecules following such manipulations enabled a quantitative assessment of the resulting fragmentation, which also revealed the type of degradation reflected in the fragmentation patterns. The use of high sensitivity flow cytometry was especially suited to investigate the degradation of dilute DNA solutions that may not be suitable for analysis using traditional methods. Notable findings of this study included: the boarderline-size of DNA chains in terms of susceptibility to shear stresses by such manipulations;discernable instability of nicked DNAs;shattering-fragmentation of DNAs by freeze-thawing or ultrasonication;effectiveness of some protection media;marked “self-protection effect” of concentrated DNA solutions. These findings support and refine our traditional knowledge on how to maintain the physical integrity of macro-DNA molecules against inevitable laboratory manipulations.
