Graziadio Lucia, Palumbo Valeria, Cipressa Francesca, Williams Byron C, Cenci Giovanni, Gatti Maurizio, Goldberg Michael L, Bonaccorsi Silvia
Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza, Università di Roma, Rome, Italy.
Museo storico della fisica e centro di studi e ricerche Enrico Fermi, Rome, Italy.
Chromosoma. 2018 Dec;127(4):489-504. doi: 10.1007/s00412-018-0680-y. Epub 2018 Aug 18.
Many genes are required for the assembly of the mitotic apparatus and for proper chromosome behavior during mitosis and meiosis. A fruitful approach to elucidate the mechanisms underlying cell division is the accurate phenotypic characterization of mutations in these genes. Here, we report the identification and characterization of diamond (dind), an essential Drosophila gene required both for mitosis of larval brain cells and for male meiosis. Larvae homozygous for any of the five EMS-induced mutations die in the third-instar stage and exhibit multiple mitotic defects. Mutant brain cells exhibit poorly condensed chromosomes and frequent chromosome breaks and rearrangements; they also show centriole fragmentation, disorganized mitotic spindles, defective chromosome segregation, endoreduplicated metaphases, and hyperploid and polyploid cells. Comparable phenotypes occur in mutant spermatogonia and spermatocytes. The dind gene encodes a non-conserved protein with no known functional motifs. Although the Dind protein exhibits a rather diffuse localization in both interphase and mitotic cells, fractionation experiments indicate that some Dind is tightly associated with the chromatin. Collectively, these results suggest that loss of Dind affects chromatin organization leading to defects in chromosome condensation and integrity, which in turn affect centriole stability and spindle assembly. However, our results do not exclude the possibility that Dind directly affects some behaviors of the spindle and centrosomes.
有许多基因参与有丝分裂器的组装以及有丝分裂和减数分裂过程中染色体的正常行为。阐明细胞分裂潜在机制的一种有效方法是对这些基因中的突变进行准确的表型特征分析。在此，我们报告了果蝇基因diamond（dind）的鉴定和特征分析，该基因对于幼虫脑细胞的有丝分裂以及雄性减数分裂均必不可少。携带五个EMS诱导突变中任何一个的纯合幼虫在三龄期死亡，并表现出多种有丝分裂缺陷。突变的脑细胞显示出染色体浓缩不良、频繁的染色体断裂和重排；它们还表现出中心粒碎片化、有丝分裂纺锤体紊乱、染色体分离缺陷、核内复制中期以及超倍体和多倍体细胞。在突变的精原细胞和精母细胞中也出现了类似的表型。dind基因编码一种不保守的蛋白质，没有已知的功能基序。尽管Dind蛋白在间期细胞和有丝分裂细胞中均表现出相当分散的定位，但分级分离实验表明，一些Dind与染色质紧密相关。总的来说，这些结果表明Dind的缺失会影响染色质组织，导致染色体浓缩和完整性缺陷，进而影响中心粒稳定性和纺锤体组装。然而，我们的结果并不排除Dind直接影响纺锤体和中心体某些行为的可能性。
