8kb genomic fragment carrying bcd.
embryonic neuroblast & abdomen
Only 50% of embryos derived from females carrying six copies of bcd+ (two wild-type genomic copies and four copies of bcd+t8) (6bcd embryos) hatch into larvae, and only 60% of these larvae survive to adulthood. The cephalic furrow is displaced posteriorly and the clypeolabrum is significantly larger in 6bcd embryos compared to embryos derived from females carrying four copies of bcd+ (two wild-type genomic copies and two copies of bcd+t8) (4bcd embryos). Clusters of free floating cells are often seen in the space around the clypeolabrum after stage 12 in 6bcd embryos. The more posterior the cephalic furrow is misplaced in individual 6bcd embryos, the lower the probability of hatching. 6bcd embryos that fail to hatch show five classes of phenotype: 37% (Class I) first appear abnormal during head involution (stage 14). Head involution is not completed, as the dorsal ridge cannot envelop the tip of the enlarged clypeolabrum, often resulting in a large mass anterior to the dorsal ridge constriction. Many of these embryos do not reach stage 17, due to abnormalities affecting posterior development. 27% (Class 2) show yolk leakage outside the gut into the head cavity or intervitelline space, usually during or after stage 12-13. 17% (Class 3) develop normally until stage 17. 10% (Class 4) cease development before completing germ band retraction in stage 12. These embryos develop a large void in the intervitelline space that contains many dead cells. 10% (Class 5) show unsynchronised cellularisation. 70% of 6bcd embryos and larvae have cuticle abnormalities, ranging from missing or fused abdominal denticle belts to grossly malformed denticles, or a failure to develop any visible cuticle segmentation. 55% of 6bcd embryos have abnormal mouthparts. 50% of 6bcd embryos have defects in the abdominal neuroblasts and in the peripheral neurons. There is an increase in cell death in the expanded head domain of 6bcd embryos compared to wild-type. 15% of 4bcd embryos have one missing or a pair of fused denticle belts.
bcd+t8 has increased cell death | embryonic stage phenotype, suppressible | heat sensitive | partially by MabiKK106905/Scer\GAL4hs.PB
+/Df(2L)ED784, bcd+t8 has partially lethal phenotype
MabiKK106905, Scer\GAL4hs.PB, bcd+t8 has lethal - all die during embryonic stage | heat sensitive phenotype
bcd+t8.7/bcd+t8 is a suppressor of embryo | anterior phenotype of trkunspecified
MabiKK106905, Scer\GAL4hs.PB, bcd+t8 has embryonic head | heat sensitive phenotype
A 1-hr heat shock during early embryogenesis in animals expressing MabiKK106905 via Scer\GAL4hs.PB in a 6x bcd (two inserts of bcd+t8, homozygous) background results in embryonic lethality and a significantly greater frequency of embryos with head defects (expanded head domains or abnormality in mouth hook formation, or both) than in controls. The increased cell death in the head domain of 6x bcd embryos is partially suppressed by expression of MabiKK106905.
The relative viability of Df(2L)ED784 heterozygotes (lacking the Mabi gene) is reduced in a 6x bcd (two inserts of bcd+t8, homozygous) background to about 60% of that in 2x bcd (wild type) background.
