Exploring the evolutionary history of centrosomes

The centrosome is the main organizer of the microtubule cytoskeleton in animals, higher fungi and several other eukaryotic lineages. Centrosomes are usually located at the centre of cell in tight association with the nuclear envelope and duplicate at each cell cycle. Despite a great structural diversity between the different types of centrosomes, they are functionally equivalent and share at least some of their molecular components. In this paper, we explore the evolutionary origin of the different centrosomes, in an attempt to understand whether they are derived from an ancestral centrosome or evolved independently from the motile apparatus of distinct flagellated ancestors. We then discuss the evolution of centrosome structure and function within the animal lineage.     

Immobilization of acetylcholinesterase in nanofibrous PVA/BSA membranes by electrospinning

Electrospinning, a simple and versatile method to fabricate nanofibrous supports, has attracted continuous attention in the field of enzyme immobilization. In this study, acetylcholinesterase (AChE) has been successfully immobilized in PVA nanofibers via electrospinning of a mixture of AChE, BSA as an enzyme stabilizing additive and PVA. The maximum activity recovery of immobilized AChE was about 40%. In comparison with free enzyme, the immobilized AChE showed improved stability while retaining a considerable amount of activity at lower pH values. Moreover, the immobilized AChE retained >34% of its initial activity when stored at 30°C for 100 days and retained 70% of its initial activity after ten consecutive reactor batch cycles.     

Operational aspects of antibody affinity constants measured by liquid-phase and solid-phase assays.

The association constant of monoclonal antibodies (Mabs) to tobacco mosaic virus has been determined in solution and solid-phase binding assays. The ELISA equilibrium titration method developed by Friguet et al. (1985) was found to be suitable for large antigens such as viruses. In the case of intact IgG antibody, it gave equilibrium constant (K) values ca 30% lower than those obtained by classical solution-phase assay while in the case of Fab', the same values were obtained in both assays. Solid-phase binding assays gave higher K values than solution-phase assays by a factor which varied with the Mab tested (1.5- to 5.4-fold higher). Furthermore, in solution-phase assay, K values were found to depend on the antibody concentration used in the assay. These results confirm the operational nature of antibody affinity constants and indicate that in order to compare the affinity of different Mabs in a meaningful way, it is necessary to use a single technique under standardized conditions.