embryos have disorganised and/or missing muscle fibers (lateral transverse muscles 3 and 4 and the segment border muscle).
embryos have a significantly reduced percentage presence of lateral transverse muscle 4 and a significantly increased number of nuclei in transverse muscle 4 compared to controls. In hemisegments with four LT muscles, mid1
embryos show a shift in fate of the LT4 muscle towards LT1-3: the most posterior LT muscle is no longer shifted dorsally and contains an increased number of nuclei compared to controls.
mutant embryos exhibit gonad development defects that are similar in penetrance and severity to midB23
An additional, ectopic eve
-postive neuron is observed within the nerve cord in 35-38% of hemisegments in ~14 hour-old mutant embryos. In midlos1
embryos, the ectopic neuron is seen in 30-39% of hemisegments; in mid2
embryos, the ectopic neuron is seen in 33-34% of hemisegments; in mid1
embryos, the ectopic neuron is seen in 63-66% of hemisegments. Further experiments suggest this is an ectopic RP2 (eRP2) neuron, resulting from the transformation of a wild type neuron termed the 'M-neuron', with an ectopic GMC-1-like cell and a RP2 sib-like cell also present. This extra RP2/sib lineage is formed 2-2.5 hours after the development of the bona fide RP2 lineage.
The longitudinal tracks are interrupted and the posterior commissures are thinner than normal in mid1
The RP1 and RP3 motor axons stall or follow longitudinal axons in homozygous embryos (in wild-type embryos they exit the central nervous system towards the periphery).
Sensory axons in the peripheral nervous system branch excessively or cross segment borders in mutant embryos.
mutant embryos show a significant loss of NB1-1 in the odd-numbered abdominal segments (77.3% and 80% loss, respectively) while the loss of NB1-1 in the even-numbered abdominal segments is minimal (6.8 and 5%).
Stage 17 mid1
embryos show a partially penetrant heart phenotype, in which some embryos show defects in the alignment of cardioblasts and pericardial cells.
Stage 16 mid1
homozygous embryos have a normal number of cells in the dorsal vessel, which has normal overall morphology. But they have increased numbers of elongated, putative ostia forming cells per hemisegment in the heart region and a corresponding decrease in numbers of dorsal vessel cells expressing cardioblast markers.
Homozygous larvae show loss of denticles predominantly in the ventral-most region of odd-numbered segments.
Denticle bands are defective in the ventral midline.