Grimwade B G, Muskavitch M A, Welshons W J, Yedvobnick B, Artavanis-Tsakonas S
Dev Biol. 1985 Feb;107(2):503-19. doi: 10.1016/0012-1606(85)90331-8.
The Notch locus of Drosophila melanogaster profoundly affects differentiation of the central nervous system in the early embryo. Previous molecular studies suggested that the locus spans 40 kb of DNA and encodes a 10.5-kb poly(A)+ RNA. The results of genetic, cytogenetic, and molecular studies of newly induced and preexisting Notch alleles are reported. Molecular analysis of 5' flanking mutations defines a distal limit for the locus, and transcriptional activity of Notch in relation to that of flanking transcription units provides evidence regarding the proximal limit. Examination of a set of mutable alleles implicates a foldback transposable element as the basis of chromosomal instability, and shows that insertion sequences within the locus do not necessarily result in a mutant phenotype. The results are discussed with regard to existing developmental and genetic analyses, and a molecular model is proposed that attempts to explain the pleiotropic action of Notch.
黑腹果蝇的Notch基因座在早期胚胎中对中枢神经系统的分化有深远影响。先前的分子研究表明，该基因座跨越40 kb的DNA，编码一个10.5 kb的聚腺苷酸化（poly(A)+）RNA。本文报道了对新诱导的和先前存在的Notch等位基因进行遗传、细胞遗传学和分子研究的结果。对5'侧翼突变的分子分析确定了该基因座的远端界限，Notch与侧翼转录单位的转录活性关系为近端界限提供了证据。对一组可变等位基因的研究表明，一种回文转座元件是染色体不稳定的基础，并且该基因座内的插入序列不一定会导致突变表型。本文结合现有的发育和遗传分析对结果进行了讨论，并提出了一个分子模型，试图解释Notch的多效性作用。
