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FB2026_01
,
released March 12, 2026
Polytene chromosomes normal
A T>C transition at position 9408 in the N cDNA sequence within the highly conserved GU-rich Downstream Sequence Element (DSE) of the consensus polyadenylation site. This results in increased N mRNA 3' processing and polyadenylation, an increased level of mature N mRNA, and, ultimately, a much higher level of N[intra] compared to controls.
Nucleotide substitution: T9408C.
Not associated with a missense mutation in the intracellular domain, as was reported in FBrf0051853. No amino acid mutation has been detected in the open reading frame. The mutant lesion appears to map outwith the coding region.
FlyBase curator comment: stated to contain a 3bp insertion at 3' end of the opa repeat (resulting in an additional Gln residue) and the amino acid replacement T2453I. However, FBrf0123050 indicates that this was in error and that the mutation lies outside the coding region.
T3172277C
Nnd-1-dse embryos are more or less wild type at the permissive termperature of 18[o]C and mutant at the restrictive temperature of 29[o]C. Embryonic mortality is about 60% at the restrictive temperature.
Nnd-1-dse embryos, transferred to the restrictive temperature half an hour before N signalling is used to specify neuronal and epidermal precursor cells, manifest varying degrees of loss of neuronal cells. About 50% of each stage of Nnd-1-dse embryos manifest syndromes of defects consistent with increased N signalling.
Wing margin shows notches.
Nnd-1-dse is temperature-sensitive. In homozygotes at 29[o]C, the eyes are rough and reduced in size, there is extreme wing notching and wing veins are thick; at 25[o]C, the abnormalities are less severe and at 18[o]C, the eyes are normal and the wings are nicked.
Wing notching and thickened veins when homozygous or hemizygous.
Homozygous females and hemizygous males have N-like wings with thickened veins. The notching effect is lost at cold temperatures, but the thickened veins remain.
Nnd-1-dse has phenotype, enhanceable by Hsc70-4195/Hsc70-4[+]
A 'N[nd-1]' stock obtained from Spyros Artavanis-Tsakonas (termed 'SAT N[nd-1]') was found to contain a mixture of two different chromosomes: (i) the Nnd-1-dse mutation alone (at relatively low frequency); and (ii) the Nnd-1-dse mutation together with the 41 bp deletion within the N coding region described by Harding-Theobald et al. 2007 (FBrf0195930). A 'N[nd-1]' stock obtained from the Drosophila Stock Center (termed 'DSC N[nd-1]') contains only the chromosome containing both lesions. The Nnd-1-dse lesion appears to have been the original mutation, with 'N[nd-1]' flies originally containing this mutation alone. However, the chromosome containing both the Nnd-1-dse lesion and the 41 bp deletion within the N coding region has almost completely displaced the original chromosome in the 'SAT N[nd-1]' stock and has completely displaced it in the 'DSC N[nd-1]' stock.
FlyBase curator comment: The 'N[nd-1]' stock has been found to have acquired a second mutation in N over time (see FBrf0209477 for details). The Nnd-1-dse lesion (mutation in the Downstream Sequence Element of the consensus polyadenylation site) appears to have been the original mutation, with a 41 bp deletion within the N coding region occurring later. Data in FlyBase curated from individual papers using 'N[nd-1]' have been retained under the N[nd-1] allele record (FBal0012890), which represents the double mutant chromosome, unless it is clear that the chromosome being studied contains only the original lesion, in which case the data has been moved to the Nnd-1-dse allele record (FBal0282136). It is thus possible that some of the papers and curated data listed under N[nd-1] in FlyBase (especially information from older papers) describe experiments carried out using the Nnd-1-dse chromosome, but there is insufficient information to be sure. (date: 130225).