Ncd is a kinesin-related microtubule motor protein ofDrosophilathat plays essential roles in spindle assembly and function during meiosis in oocytes and mitosis in early embryos. Antibody staining experiments have localized the Ned motor protein to spindle fibers and spindle poles throughout the meiotic and early mitotic divisions, demonstrating that Ncd is a spindle motor.We have madencd-gfpgene fusions with wild-type and S65Tgfpand expressed the chimaeric genes inDrosophilato target GFP to the spindle. TransgenicDrosophilacarrying thencd-gfpgene fusions in an ncd null mutant background are wild type with respect to chromosome segregation, indicating that the Ncd-GFP fusion proteins can replace the function of wild-type Ncd. The Ncd-GFP fusion proteins in transgenicDrosophilaare expressed under the regulation of the nativencdpromoter.Analysis of liveDrosophilaoocytes and early embryos shows green fluorescent spindles, demonstrating association of Ncd-GFP with meiotic and mitotic spindles. In mitotic spindles, Ncd-GFP localizes to centrosomes (Fig. 1a) and spindle fibers (Fig. 1b).