MRC Laboratory of Molecular Biology, Cambridge CB2 2QH, England.
Genetics. 1985 Oct;111(2):287-310. doi: 10.1093/genetics/111.2.287.
Nine amber suppressor mutations were isolated in the nematode Caenorhabditis elegans by reverting amber alleles of a sex-determining gene, tra-3. One suppressor maps to a known locus, sup-5 III , but the other eight map to three new loci, sup-21 X (five alleles), sup-22 IV (two alleles) and sup-23 IV (one allele). Amber alleles of tra-3 and of a dumpy gene, dpy-20, were used to measure the efficiency of suppression; the sup-21 and the sup-22 alleles were both shown to be heterogeneous and generally weaker suppressors than sup-5 alleles, which are homogeneous. The spectrum of mutations suppressed by a strong sup-21 allele, e1957, was investigated and compared to the spectra for the amber suppressors sup-5 III and sup-7 X, using amber alleles in 13 assorted genes. Some of the differences between these spectra may be due to limited tissue specificity in sup-21 expression.-Suppression of dpy-20 was used to show that the sex-linked suppressors sup-7 and sup-21 are not dosage compensated in male (XO) relative to hermaphrodite (XX).-Several uses of amber suppressors are critically discussed: for identifying null mutations, for varying levels of gene activity and for detecting maternal mRNA.
通过回复性转变基因 tra-3 的琥珀色等位基因,在秀丽隐杆线虫中分离出 9 个琥珀色抑制突变。一个抑制子映射到一个已知的位置 sup-5 III ,但其他 8 个映射到三个新的位置 sup-21 X (5 个等位基因)、sup-22 IV (2 个等位基因)和 sup-23 IV (1 个等位基因)。tra-3 和矮胖基因 dpy-20 的琥珀色等位基因被用来测量抑制效率;sup-21 和 sup-22 等位基因都显示出异质性,通常比 sup-5 等位基因弱,而 sup-5 等位基因是同质的。使用 13 个不同基因中的琥珀色等位基因,研究了强 sup-21 等位基因 e1957 抑制的突变谱,并与琥珀色抑制子 sup-5 III 和 sup-7 X 的谱进行了比较。这些谱之间的一些差异可能是由于 sup-21 表达的组织特异性有限。-抑制 dpy-20 被用来表明性连锁抑制子 sup-7 和 sup-21 在雄性(XO)相对于雌雄同体(XX)中没有剂量补偿。-几个琥珀色抑制子的用途受到了严格的讨论:用于鉴定缺失突变、用于改变基因活性水平和用于检测母体 mRNA。