Haste makes waste: restricting intracellular traffic in Drosophila

Dr. Welte is visiting us from the University of Rochester. He is an Associate Professor of Biology at his home institution.

Cells are dynamically organized, and the spatial and temporal distribution of many molecules is precisely controlled. I will discuss two distinct trafficking events during Drosophila development and how delaying/restricting this trafficking benefits the organism. 1) In oocytes, the microtubule motor kinesin-1 delivers oskar RNP particles to the posterior pole, a process critical for embryo polarity and germ-cell formation. We find that the motor-binding protein Klar is essential for correct timing of this transport: in klar mutants, RNPs arrive prematurely and fail to be anchored correctly. 2) In embryos, maternally provided histones are first sequestered on lipid droplets, the fat-storage sites of the cell, before they relocate to nuclei to assemble chromatin. By disrupting the histone anchor on lipd droplets, we find that lack of droplet binding destabilizes the maternal histone resevoir and - when new histone synthesis is compromised - leads to mitotic defects and death.