The birth of the centromere.

The centromere is the region of the eukaryotic chromosome that determines kinetochore formation and sister chromatid cohesion. Centromeres interact with spindle microtubules to ensure chromatid segregation during mitosis and homologous chromosome segregation during meiosis I. In recent years, the overall organization of centromeres in several eukaryotic species has been described, yet the mechanisms of centromere definition remain elusive.

Characterization by atomic force microscopy and cryoelectron microscopy of tau polymers assembled in Alzheimer's disease.

The structure of the Paired Helical filaments (PHF), a polymer of the microtubule associated protein tau, has been studied by Atomic Force Microscopy (AFM) and by cryoelectron microscopy. Mica and graphite were used as substrates in the AFM analysis with no differences in the results. A banding pattern of 8-12 nm width within the helical structure is found when detailed analysis of the data is performed.