Abstract. The European-funded MOZAIC programme (Measurements of ozone and water vapour by Airbus inservice aircraft) has been operational since 1994 aboard 5 commercial Airbus A340. It has gathered ozone and water vapour data between the ground and an altitude of 12 km from more than 20 000 long-range flights. A new infrared carbon monoxide analyser has been developed for installation on the MOZAIC equipped aircraft. Improvements in the basic characteristics of a commercial CO analysers have achieved performance suitable for routine aircraft measurements : ±5 ppbv, ±5% precision for a 30 s response time. The first year of operation on board 4 aircraft with more than 900 flights has proven the reliability and the usefulness of this CO analyser. The first scientific results are presented here, including UTLS exchange events and pollution within the boundary layer.

The high frequency of late sequelae in EA type III justifies regular and multidisciplinary follow-up through to adulthood.

megakaryocytes are unique mammalian cells that undergo polyploidization (endomitosis) during differentiation, leading to an increase in cell size and protein production that precedes platelet production. Recent evidence demonstrates that endomitosis is a consequence of a late failure in cytokinesis associated with a contractile ring defect. Here we show that the non-muscle myosin IIB heavy chain (mYH10) is expressed in immature megakaryocytes and specifically localizes in the contractile ring. mYH10 downmodulation by short hairpin RnA increases polyploidization by inhibiting the return of 4n cells to 2n, but other regulators, such as of the G1/s transition, might regulate further polyploidization of the 4n cells. Conversely, re-expression of mYH10 in the megakaryocytes prevents polyploidization and the transition of 2n to 4n cells. During polyploidization, mYH10 expression is repressed by the major megakaryocyte transcription factor RunX1. Thus, RunX1-mediated silencing of mYH10 is required for the switch from mitosis to endomitosis, linking polyploidization with megakaryocyte differentiation.