Song Mi Hye, Medley Jeffrey C, Kuwada John Y
1 Department of Biological Sciences, Oakland University , Rochester, Michigan.
2 Department of Molecular, Cellular and Developmental Biology, University of Michigan , Ann Arbor, Michigan.
Zebrafish. 2017 Aug;14(4):311-321. doi: 10.1089/zeb.2017.1427. Epub 2017 May 10.
The zebrafish curly fry (cfy) mutation leads to a dramatic increase in mitotic index and cell death starting during neural tube formation. The mutant phenotype is cell autonomous and does not result from defects in apical/basal polarity within the neuroepithelium. The increase in mitotic index could be due to increased proliferation or cell cycle arrest in mitosis. cfy embryos were analyzed to examine these two possibilities. By labeling embryos with a pulse of BrdU and anti-phospho-histone 3 and examining the DNA content by fluorescence activated cell sorting, we show that cfy mutants exhibit no increase in proliferation, but a significant increase in the number of cells arrested in mitosis. Furthermore, time-lapse microscopy in vivo confirmed that a great majority of dividing cells arrest during mitosis and that these mitotically arrested cells die in cfy embryos. Finally, immunostaining and confocal microscopy in cfy mutant embryos revealed that mitotic cells in mutants contain aberrant centrosomes and often exhibit monopolar spindles, thereby leading to mitotic cell cycle arrest. Our results suggest that the cfy gene is required for proper centrosome assembly and mitotic spindle formation, therefore critical for normal cell division.
斑马鱼卷尾幼鱼（cfy）突变导致有丝分裂指数显著增加以及从神经管形成期开始的细胞死亡。突变体表型是细胞自主性的，并非由神经上皮内顶端/基底极性缺陷所致。有丝分裂指数的增加可能是由于增殖增加或细胞周期在有丝分裂期停滞。对cfy胚胎进行分析以检验这两种可能性。通过用BrdU脉冲和抗磷酸化组蛋白3标记胚胎，并通过荧光激活细胞分选检查DNA含量，我们发现cfy突变体的增殖没有增加，但停滞在有丝分裂期的细胞数量显著增加。此外，体内延时显微镜观察证实，绝大多数分裂细胞在有丝分裂期停滞，并且这些有丝分裂停滞的细胞在cfy胚胎中死亡。最后，cfy突变体胚胎中的免疫染色和共聚焦显微镜观察显示，突变体中的有丝分裂细胞含有异常中心体，并且经常呈现单极纺锤体，从而导致有丝分裂细胞周期停滞。我们的结果表明，cfy基因是正常中心体组装和有丝分裂纺锤体形成所必需的，因此对正常细胞分裂至关重要。
