Newmark P A, Boswell R E
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder 80309.
Development. 1994 May;120(5):1303-13. doi: 10.1242/dev.120.5.1303.
In Drosophila, the localization of maternal determinants to the posterior pole of the oocyte is required for abdominal segmentation and germ cell formation. These processes are disrupted by maternal effect mutations in ten genes that constitute the posterior group. Here, the molecular analysis of one posterior group gene, mago nashi, is presented. Restriction fragment length polymorphisms and transcript alterations associated with mago nashi mutations were used to identify the mago nashi locus within a chromosomal walk. The mago nashi locus was sequenced and found to encode a 147 amino acid protein with no similarity to proteins of known or suspected function. The identification of the mago nashi locus was confirmed by sequencing mutant alleles and by P element-mediated transformation. Nonsense mutations in mago nashi, as well as a deletion of the 5' coding sequences, result in zygotic lethality. The original mago nashi allele disrupts the localization of oskar mRNA and staufen protein to the posterior pole of the oocyte during oogenesis; anterior localization of bicoid mRNA is unaffected by the mutation. These results demonstrate that mago nashi encodes an essential product necessary for the localization of germ plasm components to the posterior pole of the oocyte.
在果蝇中，母源性决定因子定位于卵母细胞的后极对于腹部体节形成和生殖细胞形成是必需的。这些过程会被构成后组的十个基因中的母性效应突变所破坏。本文展示了对后组基因之一无尾（mago nashi）的分子分析。利用与无尾突变相关的限制性片段长度多态性和转录本改变，在染色体步移中鉴定出无尾基因座。对无尾基因座进行测序，发现其编码一个147个氨基酸的蛋白质，与已知或推测功能的蛋白质没有相似性。通过对突变等位基因测序和P因子介导的转化证实了无尾基因座的鉴定。无尾基因中的无义突变以及5'编码序列的缺失会导致合子致死。原始的无尾等位基因在卵子发生过程中破坏了osk基因mRNA和staufen蛋白定位于卵母细胞后极的过程；而bicoid基因mRNA的前部定位不受该突变影响。这些结果表明，无尾基因编码一种对于种质成分定位于卵母细胞后极所必需的关键产物。
