bk2 hits Tl
The 97D1-2 breakpoint is located in the 6.0 kb EcoRI fragment of the Toll clone (Hashimoto, Hudson and Anderson, 1988, Cell 52: 269-79)
Df(3R)Tl-X/Df(3R)ro-XB3 embryos show altered targeting of the ISNb pathway. The nerve endings at the cleft between muscles 6 and 7 are reduced in size, the nerve terminals synapsed to muscle M12 are greatly reduced and the nerve terminals synapsed to muscle M13 are expanded compared to controls.
Df(3R)Tl-X/Df(3R)ro80b animals fail to hatch, but have no obvious morphological abnormalities in the gut, nervous system or musculature. The unhatched larvae do not perform normal hatching behaviour; the frequency of head swinging is reduced by 97% compared to wild type and reiterated cycles of head swinging are almost never seen, in contrast to wild type. On mechanical removal from the eggshell at 36 hours after egg laying, the larvae appear normal in morphology and respond to a touch on the side by twitching their bodies and retracting their heads, as is seen for wild-type larvae, although some mutant larvae are slower to respond. Df(3R)Tl-X/Df(3R)ro-XB3 embryos hatch.
Df(3R)Tl-X/Df(3R)ro-XB3 transheterozygotes are Tl null embryos. RP3 motoneuron axon pathfinding is normal, but the growth cone often misinnervates non-target muscle cells. SNa growth cones develop normally but SNb growth cones lose targeting accuracy. SNb ending at muscle 15/16 cleft appear thicker than normal and innervation at muscle 6/7 cleft is often either missing or reduced in size.
In Df(3R)Tl-X/Df(3R)ro-XB3 embryos, 12.1% of hemisegments lack normal innervation of muscle fibers 7 and 6 (though innervation of muscles 15 and 16 is normal), and 29.4% of hemisegments have ectopic endings on muscle fibers 7 and 6 (compared to 0% for muscles 15 and 16). Aberrant numbers of RP motoneurons were detected in 15.5% of hemisegments per embryo, and the positioning of cells is noticeably more irregular than in wild type. The most common phenotype is a hemisegment missing one RP motoneuron in the position of either RP1 or RP4. 86% of mutant animals examined show this phenotype. Embryos and larvae (both Df(3R)Tl-X/Df(3R)ro-XB3 and deficiency heterozygotes) show an average of 46.1% of hemisegments per larva with one or more errors in the muscle pattern. Errors include duplications, missing fibers and misinserted fibers.
Heterozygosity for this deletion has no effect on the mutant ovarian phenotype of ovoD2.
heterozygous females viable heterozygous females fertile