|Feature type||allele||Associated gene||Dmel\sca|
|Allele class||amorphic allele - genetic evidence, loss of function allele|
|Mutagen||PM hybrid dysgenesis, P-element activity|
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|Nature of the Allele|
|Mutations Mapped to the Genome|
|Associated Sequence Data|
|Nature of the lesion|
Deletion of the transcription start site.
2kb deletion at the 5' end of the gene, removing the first exon, including the transcription start site and the beginning of the open reading frame.
|Phenotype Manifest In|
adult thorax & macrochaeta
chemosensory ventral triple row & microchaeta | ectopic
dorsal triple row & microchaeta | ectopic
leg & macrochaeta
microchaeta & mesothoracic tergum | supernumerary | somatic clone
morphogenetic furrow & filopodium | somatic clone
scutum & macrochaeta
wing & macrochaeta
Mutant animals have eyes with bigger and smaller ommatidia.
Twinning of R8 photoreceptor cells is seen in mutant animals.
scaBP2 homozygous flies have extra dorsocentral, scutellar and recurved wing margin bristles (chemosensory ventral triple row + dorsal triple row).
Cytoplasmic extensions, extending from the morphogenetic furrow into scaBP2 mutant clones, follow convoluted paths rather than being straight and aligned with each other as in wild-type. Ommatidial clusters posterior to scaBP2 mutant clones that overlap the MF, display a severe over-rotation phenotype, often reaching 110o-120o. scaBP1/scaBP2 eyes and eye discs exhibit significant over-rotation of ommatidia.
scaBP2/sca1 animals exhibit abnormal patterning of the notal microchaetae. Instead of being aligned in five straight rows, as seen in wild-type, they are arranged chaotically. During pupal development from 13 to 24 hours post fertilisation, the sensory organ precursors (SOPs) in scaBP2 mutants are poorly aligned from early time points. They emerge in greater numbers and earlier than in wild-type. The order of appearance of the rows (1 and 5, then 3 then 2 and 4) is less strict than in the wild-type, although rows 1 and 5 do seem to appear first. The only row that displays, more or less, a correct initial alignment is row 1. The disorganised nature of the SOP pattern is never resolved during pupal development and becomes progressively more chaotic. SOPs move around even more than seen in wild-type but follow are complex roundabout path. The speed of movement, and orientation appear wild-type. Daughter cells are also frequently seen to move apart. When alignment is examined more closely, it is seen that mutant SOPs become less and less well aligned with time. scaBP2 somatic clones in the notum exhibit more bristles and the bristle organs move significantly more than those seen in wild-type. A greater proportion of mutant bristles are found on the borders of clones, suggesting a movement towards surrounding wild-type tissue.
40% of mutant ommatidia contain two or three R8s derived from the R8 equivalence group. R8s can be adjacent or not, indicating that selection may be stochastic.
Heterozygous mutant animals display a bristle density that is slightly higher than the wild-type. Homozygous mutants show a marked increase in density, as well as bristles that are less evenly spaced than wild-type: The acrostichal microchaetes also fail to align into rows. Despite this disorganisation, bristle organs are never adjacent, each bristle is surrounded by epidermal cells. Occasionally in homozygous mutants, double-bristle shafts and/or sockets are observed. These structures are due to abnormal fate assignments of the five cells of a single bristle organ. The precise consistent spatial arrangement of these cells in wild-type is lost, also cells from a single lineage are occasionally situated some distance from each other. Homozygous mutant larvae show an excess of more closely spaced microchaetae precursors. All of the precursors including the supernumerary ones, form together in a short period of time and by 15 hrs post pupariation. When homozygous mutant somatic clones are made in the notum the spacing between bristles is approximately wild-type. The epithelium of homozygous mutant animals is disorganised. The epithelium appears uneven, holes are visible between cells. The cuticle is thinner, deposited in irregular layers, and separated from the epithelium. Mutant cells are also often of irregular shape. Adherens and septate junctions are present in the mutant but are reduced in number and appear to be modified. Adherens junctions are often located less apically and septate junctions appear larger than normal.
Several bifurcated sensilla are seen on the third antennal segment.
Approximately 50% of ommatidia contain the normal number and arrangement of photoreceptor cells, although interommatidial spacing and orientation of individual ommatidia is variable. The remaining ommatidia contain more than one R8 cell and a variable number of other photoreceptor cells, in different arrangements. The number of R8 cells is increased in scaBP2/scaUM2 Nl1N-ts1 double mutants compared to Nl1N-ts1 single mutants, and no regular array of R8 cells can be seen.
Eyes have oversized facets with too many photoreceptors, or two or more normal R-cell complements enclosed by only one set of pigment cells. Some ommatidia have too few photoreceptor cells or altered orientation with respect to each other. Eye discs of mutants reveal irregular ommatidial spacing in the morphogenetic furrow. More than one cell per cluster can become R8.
scaBP2 has visible | recessive phenotype, suppressible | partially by Scer\GAL4sca-73-1/sca::Hsap\FGAScer\UAS.cLa
|Phenotype Manifest In|
|NOT Enhanced by|
scaBP2 has adult thorax & macrochaeta phenotype, suppressible | partially by Scer\GAL4sca-73-1/sca::Hsap\FGAScer\UAS.cLa
|NOT suppressed by|
|NOT Enhancer of|
|NOT Suppressor of|
The addition of Gp1503/Gp1504 has no effect on the scaBP2 eye phenotype. When scaBP2 is added to Gp150Scer\UAS.cLa, Scer\GAL4dpp.blk1 animals, no effect is seen on the Gp150Scer\UAS.cLa wing margin phenotype.
The increased bristle number in ed4.12; scaBP2 double homozygotes is consistent with an additive rather than a synergistic effect of the two muations.
sca::Hsap\FGAScer\UAS.cLa or sca::Hsap\FGBC286A.Scer\UAS expressed under the control of Scer\GAL4sca-73-1 partially rescues the scaBP2/sca73-1 extra thoracic bristle phenotype. sca::Hsap\FGGScer\UAS.cLa expressed under the control of Scer\GAL4sca-73-1 does not rescue the scaBP2/sca73-1 extra thoracic bristle phenotype and may increase the number of ectopic bristles compared to the number seen in scaBP2/sca73-1 flies.
|Complementation & Rescue Data|
|Fails to complement|
|Partially rescued by|
|Not rescued by|
|Stocks ( 1 )|
|Notes on Origin|
|External Crossreferences & Linkouts|
|Synonyms & Secondary IDs ( 1 )|
|Secondary FlyBase IDs|
|References ( 22 )|
|Generate a list of|
|List References by type|
|Recent research papers ( 2 )|