Schiefelbein J W, Raboy V, Kim H Y, Nelson O E
Laboratory of Genetics, University of Wisconsin, Madison 53706.
Basic Life Sci. 1988;47:261-78. doi: 10.1007/978-1-4684-5550-2_19.
The bz-m13 allele of maize contains a defective Suppressor-mutator (dSpm) transposable element and gives rise to a variety of stable and unstable derivatives in the presence of an autonomous Suppressor-mutator (Spm) element. The dSpm-13 element of bz-m13 consists of 2,241 base pairs (bp) and is located within the second exon of the bronze-1 (bz) gene. A number of the stable derivatives, both functional and nonfunctional, derived from bz-m13 were characterized molecularly. Results from genomic DNA blotting experiments indicate that the dSpm-13 element had excised from the locus in each stable derivative analyzed. The unstable derivatives bz-m13CS9 and bz-m13CS6 contain dSpm elements in the same position and orientation as the dSpm-13 element, but they differ in the length of the element. The dSpm-13CS9 element is 902 bp and arose via a deletion between two 5-bp direct repeats within the dSpm-13 element. The dSpm-13CS6 element is 2,239 bp and only differs from dSpm-13 by a 2-bp deletion at the end of one of the 13-bp terminal inverted repeats. The effect of these deletions on the frequency and timing of Spm-induced excision is discussed herein. In the absence of Spm, each of the bz-m13 alleles conditions a nonmutant phenotype despite the presence of the insertions in the second exon. The role of RNA splicing in this phenomenon and the recent finding of an acceptor splice site within the terminal inverted repeat are also discussed.
玉米的bz - m13等位基因含有一个有缺陷的抑制子 - 突变子（dSpm）转座元件，在存在自主抑制子 - 突变子（Spm）元件的情况下会产生各种稳定和不稳定的衍生物。bz - m13的dSpm - 13元件由2241个碱基对（bp）组成，位于青铜色1（bz）基因的第二个外显子内。对从bz - m13衍生的许多稳定衍生物，包括功能性和非功能性的，进行了分子特征分析。基因组DNA印迹实验结果表明，在所分析的每个稳定衍生物中，dSpm - 13元件已从该位点切除。不稳定衍生物bz - m13CS9和bz - m13CS6在与dSpm - 13元件相同的位置和方向上含有dSpm元件，但它们在元件长度上有所不同。dSpm - 13CS9元件为902 bp，是通过dSpm - 13元件内两个5 bp直接重复序列之间的缺失产生的。dSpm - 13CS6元件为2239 bp，仅与dSpm - 13在13 bp末端反向重复序列之一的末端有一个2 bp的缺失。本文讨论了这些缺失对Spm诱导切除的频率和时间的影响。在没有Spm的情况下，尽管第二个外显子中有插入序列，每个bz - m13等位基因都表现出非突变表型。还讨论了RNA剪接在这一现象中的作用以及最近在末端反向重复序列内发现的一个受体剪接位点。
