77E2;[>78A4]
77E2-77E4;78A2-78A4
bk1 << knrl << fng << bk2
In Df(3L)ri-XT1 mutant embryos, the developing small intestine and the rectum epithelia in the hindgut and the esophagus epithelium in the foregut start to lose integrity in mutants leading to a disconnection is seen of the hindgut and the midgut. Larger nuclei and larger cells are seen in the hindgut epithelial cells of mutant embryos.
The Df(3L)ri-XT1 chromosome does not act as a dominant suppressor of telomeric silencing (assayed using the effect of the chromosome on the eye colour phenotype of flies carrying "P{wvar}KR3-2", a stable "brown-red" variant of the P{3'WP-2,wvar}2Lt insertion).
Mutant embryos have defects in the visceral branch of the tracheal system. Only five tracheal metameres develop, and the tracheal cells do not migrate. When partially rescued with knitRa, segmentation is restored, but dorsal and ventral branches have breaks in the dorsal trunk. Embryos usually lack the visceral branches and if present they are very rudimentary.
Tracheal metameres in remaining 5 abdominal segments of homozygotes show much more disrupted phenotype than kni8. Rudimentary tracheal metameres invaginate but lack primary branching and interconnections. When combined with knitRa, dorsal trunk formation is similar to wild type, though dorsal outgrowth fails and lateral trunk fusion is only partial. Visceral and ganglionic tracheal branches fail to reach the gut and nervous system. Lack of tracheal branch formation is caused by failure of cell migration.
Homozygous embryos display abdominal segmentation defect. One copy of Res1r1 lacks the rescued abdominal segments.
Deletion of abdominal segments, severe head defect and absence of SNS. SNS defect can be rescued by expression of either the knitRa or knrlkni.PR construct. Phenotypic rescue with the knrl transgene is dose dependent, three copies provides an almost normal head as strong as that observed with two copies of kni transgene.
Mutant abdominal phenotype of Df(3L)ri-XT1 embryos can be rescued by P{kniSH} but only weak rescue of head defects.
The 77E1-4 quadruplet is attenuated, but a distal portion is still present. The 78A5,6 doublet is present, but the 78A1,2 doublet is absent.
Left limit of break 1 from polytene analysis (citation unavailable) Right limit of break 1 from inclusion of kni (FBrf0045941) Left limit of break 2 from inclusion of fng (FBrf0076041)