A high proportion of genes involved in position effect variegation also affect chromosome inheritance
A high proportion of genes involved in position effect variegation also affect chromosome inheritance
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DOI：
10.1007/s00412-003-0272-2
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发表时间：
2004-03-01
期刊：
影响因子：
1.6
通讯作者：
Karpen, GH
中科院分区：
文献类型：
--
作者：
Le, HD;Donaldson, KM;Karpen, GH
位置效应变异（PEV）的抑制因子和增强因子与异染色质的形成和维持有关。着丝粒和其他遗传元件在异色区域的存在表明PEV的抑制因子和增强因子Su(var) s和E(var)s[总称为Mod(var)s]可能是染色体遗传所必需的。为了验证这一假设，我们筛选了59个甲基磺胺乙酯生成的果蝇Mod(var)s，以研究其对缺失部分基因定义着丝粒的小染色体（J21A）部分受损遗传的显性影响。近一半的Mod（var）显著增加或减少了J21A的传播。对纯合子突变幼虫神经母细胞的分析表明，这些突变影响细胞周期进程和原生染色体形态。测试的六个互补组中有五个显示有丝分裂异常，包括端粒融合、染色体过凝聚和低有丝分裂指数等表型。我们得出结论，Mod（var）作为一个群体，具有高度丰富的编码基本遗传功能的基因。我们提出Mod(var)s的主要功能是促进染色体遗传，而与PEV相关的基因沉默表型可能是执行这些功能所需的异色结构的次要后果。
Suppressors and enhancers of position effect variegation (PEV) have been linked to the establishment and maintenance of heterochromatin. The presence of centromeres and other inheritance elements in heterochromatic regions suggests that suppressors and enhancers of PEV, Su(var) s and E(var)s [collectively termed Mod(var)s], may be required for chromosome inheritance. In order to test this hypothesis, we screened 59 ethyl methanesulfonate-generated Drosophila Mod(var)s for dominant effects on the partially compromised inheritance of a minichromosome (J21A) missing a portion of the genetically defined centromere. Nearly half of these Mod(var)s significantly increased or decreased the transmission of J21A. Analyses of homozygous mutant larval neuroblasts suggest that these mutations affect cell cycle progression and native chromosome morphology. Five out of six complementation groups tested displayed mitotic abnormalities, including phenotypes such as telomere fusions, overcondensed chromosomes, and low mitotic index. We conclude that Mod(var)s as a group are highly enriched for genes that encode essential inheritance functions. We propose that a primary function of Mod(var)s is to promote chromosome inheritance, and that the gene silencing phenotype associated with PEV may be a secondary consequence of the heterochromatic structures required to carry out these functions.