Tau Interaction with Tubulin and Microtubules: From Purified Proteins to Cells

International audienceMicrotubules (MTs) play an important role in many cellular processes and are dynamic structures regulated by an important network of microtubules-associated proteins, MAPs, such as Tau. Tau has been discovered as an essential factor for MTs formation in vitro, and its region implicated in binding to MTs has been identified. By contrast, the affinity, the stoichiometry, and the topology of Tau-MTs interaction remain controversial. Indeed, depending on the experiment conditions a wide range of values have been obtained. In this chapter, we focus on three biophysical methods, turbidimetry, cosedimentation assay, and Förster Resonance Energy Transfer to study Tau-tubulin interaction both in vitro and in cell. We highlight precautions that must be taken in order to avoid pitfalls and we detail the nature of the conclusions that can be drawn from these methods about Tau-tubulin interaction

Fluorescein angiography and adverse drug reactions revisited: The Lions Eye experience

Background: The last major survey of adverse reactions to intravenous fluorescein angiography was performed more than 20 years ago. There have been two recent fatalities involving intravenous fluorescein in Australia. It is important to review the current incidence of adverse reactions and latest literature on the pathogenesis, prophylaxis and alternatives to intravenous fluorescein angiography

A multiwavelength study of outflows in OMC-2/3

We present new ? = 1-0 S(1) H 2, 12CO J = 2 ? 1, and 12CO J = 3 ? 2 observations of the star-forming clouds OMC-2 and OMC-3, one of the densest known groupings of outflows from low-mass young stellar objects (YSOs) in the sky. High-velocity 12CO J = 2 ? 1 gas in this region suggests that previously discovered H 2 flows are driving and entraining molecular outflows. However, the large number of sources and flows within the narrow molecular filament means it is difficult to make a firm association of molecular outflow gas with H 2 flows, except for in the case of the bipolar east-west H flow. A number of Herbig-Haro (HH) objects, including ones far to the west and east of the main ridge, are identified with H 2 knots. High-resolution spectroscopy in the ? = 1-0 S(1) line of 10 H 2 knots shows line profiles consistent with dual forward and reverse shocks. C-shock modeling suggest that asymmetries seen in suspected bow shocks could be evidence of varying magnetic field orientations throughout the cloud. One of the bow shocks in the H flow, YBD-5, can be successfully modeled by a 100 km s -1 C-shock propagating into a magnetized, 10 6 cm -3 medium, although the observations and limitations within the computer code itself do not entirely rule out J-shocks. Mass spectra of the H flow are broken power laws, which might be evidence for a jet that has two entrainment mechanisms for accelerating ambient molecular gas into the outflow. The H 2 luminosity in this flow is many times smaller than the CO mechanical luminosity, but this fact cannot rule out the possibility that a narrow highly collimated jet drives the molecular outflow, owing to uncertainties in extinction, outflow dynamic times, cooling contributions from other lines, and the wind model used. Outflows from OMC-2/3 are likely to contribute to the turbulent pumping of gas within the molecular ridge north of the Orion Nebula. High-velocity gas clumps north of the sources investigated here may represent evidence of additional undiscovered outflows from young stars

Competition between microtubule-associated proteins directs motor transport

Motor and non-motor microtubule-associated proteins (MAPs) bind to the microtubule lattice, but it is unclear how their binding activities are coordinated and how this impacts motor transport. Here the authors show how MAP competition controls microtubule access to determine the distribution and balance of motor activity