Combined SPT and FCS methods reveal a mechanism of RNAP II oversampling in cell nuclei.

Gene expression orchestration is a key question in fundamental and applied research. Different models for transcription regulation were proposed, yet the dynamic regulation of RNA polymerase II (RNAP II) activity remains a matter of debate. To improve our knowledge of this topic, we investigated RNAP II motility in eukaryotic cells by combining single particle tracking (SPT) and fluorescence correlation spectroscopy (FCS) techniques, to take advantage of their different sensitivities in order to analyze together slow and fast molecular movements.

HEXIM1 Diffusion in the Nucleus Is Regulated by Its Interactions with Both 7SK and P-TEFb.

How nuclear proteins diffuse and find their targets remains a key question in the transcription field. Dynamic proteins in the nucleus are classically subdiffusive and undergo anomalous diffusion, yet the underlying physical mechanisms are still debated. In this study, we explore the contribution of interactions to the generation of anomalous diffusion by the means of fluorescence spectroscopy and simulation.

[P-TEFb and Brd4: actors of the transcription pause release as therapeutical targets].

Most cell physiology events are dictated by the integration of perceived signals and the elaboration by cells of adapted answers via the execution of proper transcriptional programs. In order to ensure an optimal control of these answers, many regulation mechanisms have been selected throughout the evolution, thus allowing to fine-tune transcript expression. The transcriptional pause and its release by P-TEFb (Positive Transcription Elongation Factor) have been evidenced two decades ago.

Image-based adaptive optics for in vivo imaging in the hippocampus.

Adaptive optics is a promising technique for the improvement of microscopy in tissues. A large palette of indirect and direct wavefront sensing methods has been proposed for in vivo imaging in experimental animal models. Application of most of these methods to complex samples suffers from either intrinsic and/or practical difficulties.

The structural modifications induced by the M339F substitution in PBP2x from Streptococcus pneumoniae further decreases the susceptibility to beta-lactams of resistant strains.

PBP2x is a primary determinant of beta-lactams resistance in Streptococcus pneumoniae. Altered PBP2x with multiple mutations have a reduced "affinity" for the antibiotics. An important polymorphism is found in PBP2x sequences from clinical resistant strains.