Recombination between the single FRT sites that are present on each of Dscam1ED69 and Dscam15'HR-6.5.9 has resulted a single copy of Dscam1 in which the genomic region encoding exons 3 to 16 has been replaced with cDNA sequences. This copy of Dscam1 encodes a single ectodomain isoform, containing the variable exons 4.6, 6.5 and 9.9. A single FRT site is present following the cDNA sequences.
Dscam3.31.8/Dscam6.5.9 and Dscam10.27.25/Dscam6.5.9 animals die in early larval development.
Over 75% of Dscam6.5.9/Dscam23 animals survive to late pupal stages.
Dscam3.31.8/Dscam6.5.9and Dscam10.27.25/Dscam6.5.9 embryos show defects in the organisation of the central nervous system, showing severely disrupted longitudinal tracts and aberrant midline crossing.
Dscam6.5.9/Dscam23 embryos show defects in the organisation of the central nervous system, showing disrupted longitudinal tracts.
Dscam6.5.9/Dscam- animals have a highly disorganised antennal lobe with no distinct glomerular structure and olfactory receptor neurons form many ectopic termini throughout the antennal lobe.
Almost all Dscam6.5.9/Dscam- mushroom bodies completely lack one lobe (typically the dorsal lobe is missing). Dscam3.31.8/+ animals also show defects in the mushroom body in approximately 90% of cases; either one mushroom body lobe is absent (approximately 60% of cases) or one mushroom body lobe is thinner than the other (approximately 30% of cases).