Identification and Characterization of Breakpoints and Mutations on Drosophila melanogaster Balancer Chromosomes.
Identification and Characterization of Breakpoints and Mutations on Drosophila melanogaster Balancer Chromosomes.
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黑腹果蝇平衡染色体断裂点和突变的鉴定和表征。
DOI：
10.1534/g3.120.401559
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发表时间：
2020-11-05
期刊：
影响因子：
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通讯作者：
Cook KR
中科院分区：
文献类型：
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作者：
Miller DE;Kahsai L;Buddika K;Dixon MJ;Kim BY;Calvi BR;Sokol NS;Hawley RS;Cook KR
平衡子是黑腹果蝇中使用的重新排列的染色体，用于维持稳定群体中的有害突变，保留连锁遗传元件组并构建复杂的实验种群。在这里，我们评估了与常用的第三染色体平衡器上断点诱导的突变相关的表型，并且显示出非常少的有害影响。我们证明，p53 中的断点会导致辐射诱导的细胞凋亡丧失，而岩藻糖基转移酶 A 中的断点会导致神经和肠道组织中岩藻糖基化的丧失——后一项研究为肠道细胞身份提供了新的标记，并挑战了先前关于岩藻糖基化调节的结论。我们还描述了 X 或第三染色体平衡器之间共享的数千种潜在有害突变，或特定平衡器所独有的突变，包括大多数 TM3 平衡器上存在的锚蛋白 2 突变，并重申使用平衡器作为实验对照的风险。我们使用长读长测序来确认或细化重复序列中断点的两个倒位的位置，并提供证据证明其中一个倒位 In(2L)Cy 是由折返转座子插入之间的异位重组引起的，而另一个倒位 In(3R)C 干净地分离了亚端粒和端粒序列，并将亚端粒序列移动到内部染色体位置。此外，我们对 In(3R)C 的表征表明平衡子可能具有末端删除的多态性。最后，我们提出的证据表明，平衡器上的极端远端突变可以增加种群的稳定性，其目的是维持携带远端基因突变的同源染色体。总的来说，这些研究增加了我们对平衡染色体的结构、多样性和有效性的理解。
Balancers are rearranged chromosomes used in Drosophila melanogaster to maintain deleterious mutations in stable populations, preserve sets of linked genetic elements and construct complex experimental stocks. Here, we assess the phenotypes associated with breakpoint-induced mutations on commonly used third chromosome balancers and show remarkably few deleterious effects. We demonstrate that a breakpoint in p53 causes loss of radiation-induced apoptosis and a breakpoint in Fucosyltransferase A causes loss of fucosylation in nervous and intestinal tissue—the latter study providing new markers for intestinal cell identity and challenging previous conclusions about the regulation of fucosylation. We also describe thousands of potentially harmful mutations shared among X or third chromosome balancers, or unique to specific balancers, including an Ankyrin 2 mutation present on most TM3 balancers, and reiterate the risks of using balancers as experimental controls. We used long-read sequencing to confirm or refine the positions of two inversions with breakpoints lying in repetitive sequences and provide evidence that one of the inversions, In(2L)Cy, arose by ectopic recombination between foldback transposon insertions and the other, In(3R)C, cleanly separates subtelomeric and telomeric sequences and moves the subtelomeric sequences to an internal chromosome position. In addition, our characterization of In(3R)C shows that balancers may be polymorphic for terminal deletions. Finally, we present evidence that extremely distal mutations on balancers can add to the stability of stocks whose purpose is to maintain homologous chromosomes carrying mutations in distal genes. Overall, these studies add to our understanding of the structure, diversity and effectiveness of balancer chromosomes.