Henrich V C, Livingston L, Gilbert L I
Department of Biology, University of North Carolina at Greensboro 27412-5001.
Dev Genet. 1993;14(5):369-77. doi: 10.1002/dvg.1020140506.
The ecdysoneless locus in Drosophila melanogaster has been defined previously by a single conditional mutation, I(3)ecd1, that causes an ecdysteroid deficit and larval death at the restrictive temperature, 29 degrees C, although the primary role of the mutation in developmental processes has been unclear. Gene dosage and complementation studies reported here for ecd1 and five nonconditional lethal alleles indicate that the ecd locus plays prezygotic and postzygotic roles essential for normal embryonic development, the successful completion of each larval molt, adult eclosion, and female fertility. The ecd locus is also required for normal macrochaete differentiation. For each observed phenotype, the severity of mutational effects was correlated with ecd mutant genotypes. In all cases, ecd1 homozygotes were least affected. Mutants heteroallelic for ecd1 and any one of four nonconditional recessive mutations were more severely affected than ecd1 homozygotes, revealing these as hypomorphic alleles. For all phenotypic effects, mutants heteroallelic for ecd1 and a dominant mutation (ecd3D) were most severely affected. These individuals died during embryogenesis at 29 degrees C and developed no macrochaetes on the dorsal thorax when transferred to 29 degrees C during the white prepupal stage. The ecd3D mutation also caused female semisterility in heterozygotes. Ecdysteroid regulation has been implicated previously in all the developmental processes disrupted by these ecd mutations except for macrochaete differentiation.
果蝇黑腹果蝇中的无蜕皮激素基因座先前已由一个单一的条件突变I(3)ecd1定义，该突变在29摄氏度的限制温度下导致蜕皮激素缺乏和幼虫死亡，尽管该突变在发育过程中的主要作用尚不清楚。本文报道的关于ecd1和五个非条件致死等位基因的基因剂量和互补研究表明，ecd基因座在合子前和合子后发挥着对正常胚胎发育、每次幼虫蜕皮的成功完成、成虫羽化和雌性生育力至关重要的作用。正常的大刚毛分化也需要ecd基因座。对于每个观察到的表型，突变效应的严重程度与ecd突变基因型相关。在所有情况下，ecd1纯合子受影响最小。ecd1与四个非条件隐性突变中的任何一个的杂合突变体比ecd1纯合子受影响更严重，表明这些是亚效等位基因。对于所有表型效应，ecd1与一个显性突变（ecd3D）的杂合突变体受影响最严重。这些个体在29摄氏度的胚胎发育过程中死亡，并且在白色预蛹期转移到29摄氏度时，背部胸部没有发育出大刚毛。ecd3D突变在杂合子中也导致雌性半不育。先前已表明，除了大刚毛分化外，蜕皮激素调节与所有这些ecd突变破坏的发育过程有关。
