Luc Valentin

A new high resolution radioimager for the quantitative analysis of radiolabelled molecules in tissue section

We present a high-speed, high-resolution imager of beta particles. It is devoted to be used in autoradiography experiments such as receptor binding or in situ hybridization experiments, either instead of, or in complement with autoradiographic film and emulsions. It allows the user to locate and perform quantitative analyses of (3H, 14C, 35S, 33P, 32P, 125I) labelled molecules with a 15 microm spatial resolution on a 0.9 x 1.3 cm2 sensitive area. Combining recent techniques (specific scintillator thin sheets and intensified charge-coupled device (CCD)) this imager offers a wide dynamic range and real-time acquisition.

Dynamics of single-stranded DNA migration in denaturing polyacrylamide slab-gel electrophoresis.

We describe an original apparatus for the study of the dynamics of single stranded DNA migration. Four detectors based on laser‐induced fluorescence (LIF) are equidistantly placed on one migration lane, allowing repeated measurements of the same DNA band at different positions along migration. This article presents the characteristics and performances of this system and focuses on the data analysis, showing how the multiple detection scheme enables the study of band broadening and band resolution during a migration run. Our results suggest the existence of anomalous (nonthermal) diffusion of DNA molecules during the electrophoretic process.

Post-capillary laser-induced fluorescence detection without sheath-flow

The sensitivity of laser-induced fluorescence detection in capillary electrophoresis is generally limited by noise due to scattering of the excitation beam on the capillary walls. The highest sensitivities have been obtained with post-capillary detection in a sheath-flow cuvette. In this paper, we report a new method for post-capillary detection, avoiding the hydrodynamic buffer flow at the capillary outlet. In our detection scheme, the analytes coming out of the individual capillaries are kept well separated from their neighbours in the outlet detection chamber because of an adequate electric field surrounding the capillary extremities.