XTACC3–XMAP215 association reveals an asymmetric interaction promoting microtubule elongation

chTOG is a conserved microtubule polymerase that catalyses the addition of tubulin dimers to promote microtubule growth. chTOG interacts with TACC3, a member of the transforming acidic coiled-coil (TACC) family. Here we analyse their association using the Xenopus homologues, XTACC3 (TACC3) and XMAP215 (chTOG), dissecting the mechanism by which their interaction promotes microtubule elongation during spindle assembly. Using SAXS, we show that the TACC domain (TD) is an elongated structure that mediates the interaction with the C terminus of XMAP215. Our data suggest that one TD and two XMAP215 molecules associate to form a four-helix coiled-coil complex. A hybrid methods approach was used to define the precise regions of the TACC heptad repeat and the XMAP215 C terminus required for assembly and functioning of the complex. We show that XTACC3 can induce the recruitment of larger amounts of XMAP215 by increasing its local concentration, thereby promoting efficient microtubule elongation during mitosis

Fission cross sections of lead projectiles in Pb-nucleus interactions at 40 and 158 GeV/c per nucleon

The fission of lead projectiles has been investigated at the CERN SPS by the NA50 experiment. For this study, a Cherenkov quartz detector was added to the standard NA50 setup to measure the charge of projectilelike fragments. The data collected on different targets at 40 and 158 GeV/c per nucleon are presented here. The contributions arising from the nuclear and the electromagnetic fission mechanism are extracted from the measured fission cross sections; the electromagnetic contribution is then compared to the Weizsacker-Williams predictions

The J/psi normal nuclear absorption

We present a new determination of the ratio of cross-sections (J/psi)/DY as expected for nucleus-nucleus reactions if J/psi would only be normally absorbed by nuclear matter. This anticipated behaviour is based on proton-nucleus data exclusively, and compared, as a function of centrality, with updated S-U results from experiment NA38 and with the most recent Pb-Pb results from experiment NA50

psi ' production in Pb-Pb collisions at 158 GeV/nucleon

psi' production is studied in Pb-Pb collisions at 158 GeV/c per nucleon incident momentum. Absolute cross-sections are measured and production rates are investigated as a function of the centrality of the collision. The results are compared with those obtained for lighter colliding systems and also for the J/psi meson produced under identical conditions