August 10th, 2pm in H53: An exciting lecture you should definitely not miss! Ivo Telley from the Instituto Gulbenkian de Ciência in Oeiras, Portugal, will talk about the physical principles underlying nuclear division.

In Drosophila embryos, zygotic nuclei initially undergo rapid successive divisions without cytokinesis and, therefore, a vast number of nuclei share the same intracellular space in a syncytium. They need to be evenly distributed throughout a large cytoplasmic volume and brought to the cell cortex to form even-sized cells. The regular arrangement of the nuclei is vital to later embryo development, and defects that perturb this distribution are lethal. How the regular nuclear distribution during early divisions is achieved and maintained is an interesting yet unresolved question.

One of Ivo’s main research tracks is to understand the physical principles underlying the regular arrangement and precise positioning of nuclei, and the mechanism that maintain the regularity of the nuclear distribution during perturbations such as nuclear division. He will present new insight into the mechanics of nuclear distribution and point at microtubule-based molecular interactions that are involved in distance maintenance between nuclei. It is known that the microtubule cytoskeleton plays a key role in nuclear transport, and its dynamics is greatly determined by the microtubule-organizing center, the centrosome. Ivo has evidence from mitotic mutants which suggests that the centrosomes, and not the nuclei, are the spatial organizer in the early embryo.

Finally, he will present efforts in developing an extract approach to study young fertilized eggs and visualize pronuclei and sperm in time-lapse and high-resolution, something which has not been possible before. With this approach, he aims to study how Wolbachia infection in Drosophila affects the last stages of fertilization and, in particular, what causes the first mitotic division to fail.

 

 

At the Instituto Gulbenkian de Ciência in Oeiras, Portugal, Ivo is head of a multidisciplinary research team interested in the physical aspects of intracellular organization. As a model system, they study the earliest stage of Drosophila development, from the mature egg to fertilization to pre-blastoderm cleavages. They focus on pronuclear fusion in the fertilized egg and how the syncytial embryo defines the inter-nuclear distance between rapid mitotic divisions. They employ reconstitution approaches in egg explants combined with time-lapse light microscopy and image processing while taking advantage of Drosophila genetics. By applying this assay in a study of host-micro-organism interactions, they have started to investigate how Wolbachia infection in Drosophila affects the last stages of fertilization preceding developmental arrest due to cytoplasmic incompatibility.