Chicken spindling genes on W and Z chromosomes: transcriptional expressionof both genes and dynamic behavior of spindlin in interphase and mitotic cells

Contigs of genomic clones covering about 480 kb on the terminal region of t he short arm of chicken W chromosome were obtained. By applying the exon tr apping procedure on this whole region, a chicken homolog of spindling gene, chSpin-W, was identified and subcloned. A counterpart gene, chSpin-Z, was found near the centromere on the long arm of Z chromosome. Although protein -coding regions of both genes are nearly identical, a part of the 3'-untran slated region is sufficiently different to distinguish the transcript of ch Spin-W. Both chSpin-W and chSpin-Z are transcribed in early embryos. chSpin -Z is transcribed in various tissues of adult chickens, while chSpin-W is t ranscribed most prominently in ovarian granulosa and thecal cells. When fem ale chicken embryonic fibroblasts were transfected with a cDNA construct fo r red fluorescent protein or green fluorescent protein-fused spindlin or FL AG-tagged spindlin, the expressed spindlin was co-localized with SUMO-1 in nuclear dots, ND10, in interphase cells, while the expressed spindlin was l ocalized on entire chromosomes during mitosis. The localization of spindlin in ND10 reappeared after mitosis in daughter cell nuclei. A C-terminal reg ion of spindlin was suggested to be required for the localization of spindl in to ND10.