Melnikova Larisa, Georgiev Pavel
Department of Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 117334 Moscow, Russia.
Genetics. 2002 Nov;162(3):1301-12. doi: 10.1093/genetics/162.3.1301.
Telomeres of Drosophila melanogaster contain arrays of the retrotransposon-like elements HeT-A and TART. Terminally deleted chromosomes can be maintained for many generations. Thus, broken chromosome ends behave as real telomeres. It was previously shown that gene conversion may extend the broken ends. Here we found that the frequency of terminal DNA elongation by gene conversion strongly depends on the genotype. A dominant E(tc) (Enhancer of terminal gene conversion) mutation markedly increases the frequency of this event but does not significantly influence the frequency of HeT-A and TART attachment to the broken chromosome end and recombination between directly repeated sequences at the end of the truncated chromosome. The E(tc) mutation was mapped to the 91-93 region on chromosome 3. Drosophila lines that bear the E(tc) mutation for many generations have telomeres, consisting of HeT-A and TART elements, that are longer than those found in wild-type lines. Thus, the E(tc) mutation plays a significant role in the control of telomere elongation in D. melanogaster.
黑腹果蝇的端粒包含逆转座子样元件HeT - A和TART的阵列。末端缺失的染色体可以维持许多代。因此，断裂的染色体末端表现得如同真正的端粒。先前的研究表明基因转换可能会延长断裂末端。在这里我们发现，通过基因转换实现的末端DNA延伸频率强烈依赖于基因型。一个显性的E(tc)（末端基因转换增强子）突变显著增加了这一事件的频率，但对HeT - A和TART附着于断裂染色体末端的频率以及截短染色体末端直接重复序列之间的重组没有显著影响。E(tc)突变被定位到3号染色体的91 - 93区域。携带E(tc)突变多代的果蝇品系具有由HeT - A和TART元件组成的端粒，这些端粒比野生型品系中的端粒更长。因此，E(tc)突变在黑腹果蝇端粒延伸的控制中发挥着重要作用。
