Perturbed turnover of microtubule-based nutritive tubes in ovarioles of virgin and precocene-treated Dysdercus fasciatus.

During early oogenesis in Dysdercus fasciatus, anteriorly positioned nurse cells supply each oocyte with mRNA, ribosomes, and proteins via a microtubule-rich nutritive tube that lengthens as the oocyte is displaced backwards down an ovariole. Nurse cell-dependent development of an oocyte continues until the latter reaches a particular stage of oogenesis after which the nutritive tube supplying it becomes redundant and breaks down. The signal for nutritive tube breakdown is believed to derive from the oocyte, and to be developmental stage-specific. To explore this, nutritive tube turnover has been investigated following the experimental inhibition of oocyte maturation both by the prevention of mating, and also the topical application of precocene II. In each case, the nutritive tubes with their component microtubules continued to extend and failed to show normal tube redundancy, typified by microtubule rearrangement and then depolymerisation. This provided an in vivo demonstration that the dynamics of a large microtubule aggregate are influenced by the developmental state of the cytoplasm.