Mike V. DanilchikDept. Biological Structure & Function SD
Oregon Health Sciences University
611 SW Campus Drive
503 494 8568
Fax: 503 494 4666
My lab's present focus is on understanding the functions of the cytoskeleton in terminal phases of cytokinesis. In amphibian embryos, cell division is accompanied by the insertion of a new domain of basolateral plasma membrane in the cleavage plane -- a process with some similarities to compaction in morula-stage mammalian embryos. A few years ago, we discovered an unusual array of microtubules in the base of cleavage furrows of early Xenopus embryos. Recently, homologous microtubule-containing structures have been identified in other organisms as well. We hypothesized that this furrow microtubule array serves to direct basolaterally targeted post-Golgi vesicle traffic toward a localized exocytotic site during the membrane expansion of cleavage, and there is now evidence from a variety of in vivo and in vitro experiments that this idea is at least partly correct: for example, interfering with microtubules blocks membrane expansion, while experimentally placing microtubules in ectopic sites under the egg surface results in ectopic membrane addition. Interestingly, however, furrow microtubules also appear to be involved in stabilizing or propagating the actomyosin contractile ring. Present lab aims are to learn the role of microtubules in directing exocytotic vesicles to the growing basolateral surface at the cleavage plane, to understand the details of cytoskeletal assembly in the furrows of living embryos, and to investigate the relationship between furrowing and several dynamic membrane activities that appear to be important for completion of cell division. We are presently using various GFP-tagged constructs to carry out real-time and timelapse confocal analysis of these processes in living embryos.