Deak J C, Doerder F P
Department of Biology, Cleveland State University, Ohio 44115, USA.
Genetics. 1998 Mar;148(3):1109-15. doi: 10.1093/genetics/148.3.1109.
Macronuclear development in ciliates is characterized by extensive rearrangement of genetic material, including sequence elimination, chromosome fragmentation and telomere addition. Intragenic recombination is a relatively rare, but evolutionarily important phenomenon occurring in mitosis and meiosis in a wide variety of organisms. Here, we show that high frequency intragenic recombination, on the order of 30%, occurs in the developing amitotic macronucleus of the ciliate Tetrahymena thermophila. Such recombination, occurring between two nonsense transition mutations separated by 726 nucleotides, reproducibly restores wild-type expression of the SerH1 surface protein gene, thus mimicking complementation in trans heterozygotes. Recombination must be considered a potentially important aspect of macronuclear development, producing gene combinations not present in the germinal micronucleus.
纤毛虫的大核发育特征是遗传物质的广泛重排，包括序列消除、染色体片段化和端粒添加。基因内重组是一种相对罕见但在多种生物体的有丝分裂和减数分裂中具有进化重要性的现象。在此，我们表明，在嗜热四膜虫发育中的无丝分裂大核中发生了频率高达30%的高频基因内重组。这种重组发生在两个由726个核苷酸分隔的无义转换突变之间，可重复性地恢复了SerH1表面蛋白基因的野生型表达，从而模拟了反式杂合子中的互补作用。重组必须被视为大核发育的一个潜在重要方面，产生了生殖性小核中不存在的基因组合。
