Chomet P S, Wessler S, Dellaporta S L
EMBO J. 1987 Feb;6(2):295-302. doi: 10.1002/j.1460-2075.1987.tb04753.x.
The Activator (Ac) element at the waxy locus (wx-m7 allele) has the ability to undergo changes in its genetic activity and cycles between an active and inactive phase. Comparison of active Ac elements at several loci and the inactive Ac at wx-m7 by Southern blot analysis revealed that the inactive Ac sequence was not susceptible to digestion by the methylation sensitive enzyme PvuII while active elements were susceptible to PvuII digestion. Restriction digest comparisons between the clones of the active and inactive Ac elements were indistinguishable. Further analyses with the enzymes SstII and the methylation sensitive and insensitive isoschizomers EcoRII and BstNI showed the inactive Ac sequence was methylated at these sites, whereas the active Ac was hypomethylated. Although the active Ac at the wx-m7 allele in different genetic backgrounds showed differences in the Ac DNA modification pattern, at least a fraction of genomic DNA contained Ac sequences that were unmethylated at all of the internal sites we assayed. These data may suggest a role for DNA modification in the ability of Ac to transpose from the waxy locus and to destabilize unlinked Ds elements.
蜡质基因座（wx - m7等位基因）处的激活子（Ac）元件具有改变其遗传活性的能力，并在活跃期和非活跃期之间循环。通过Southern印迹分析比较几个基因座处的活跃Ac元件和wx - m7处的非活跃Ac元件，发现非活跃Ac序列不易被甲基化敏感酶PvuII消化，而活跃元件易被PvuII消化。活跃和非活跃Ac元件克隆之间的限制性消化比较没有差异。用SstII酶以及甲基化敏感和不敏感的同裂酶EcoRII和BstNI进行的进一步分析表明，非活跃Ac序列在这些位点被甲基化，而活跃Ac则是低甲基化。尽管在不同遗传背景下wx - m7等位基因处的活跃Ac在Ac DNA修饰模式上存在差异，但至少一部分基因组DNA包含在我们检测的所有内部位点均未甲基化的Ac序列。这些数据可能表明DNA修饰在Ac从蜡质基因座转座以及使未连锁的Ds元件不稳定的能力中起作用。
