A deletion of up to 1kb of genomic sequence downstream of the P{lArB}chbv40 insertion site. The insertion itself is incomplete lacking the ry gene.
chbP4 mutant embryos exhibit a moderate penetrance (38%) of ectopic midline crossing.
Homozygous embryos show ectopic crossing of the midline by axons in the central nervous system.
Third instar larval brains exhibit polyploidy and circular mitotic figures. Most cells show highly condensed chromatin. The most severe cases, cells show extensive polyploidy wit most chromosomes organised in a sphere-like conformation. Mutants have a mitotic index that is several times larger than seen in wild-type (9.3 compared to 1.14), almost all of which are arrested in metaphase or prometaphase. Circular mitotic figures are also seen.
chbP4 has abnormal neuroanatomy phenotype, enhanceable by Scer\GAL4insc-Mz1407/mspsd03376
chbP4 has abnormal neuroanatomy phenotype, enhanceable by Abl2
chbP4 has abnormal neuroanatomy phenotype, enhanceable by Abl4
chbP4 is an enhancer of abnormal neuroanatomy phenotype of Abl2
chbP4 is an enhancer of abnormal neuroanatomy phenotype of Abl4
chbP4, sli2/sli[+] has abnormal neuroanatomy phenotype
chbP4, sli2 has abnormal neuroanatomy phenotype
chbP4 has fascicle phenotype, enhanceable by Scer\GAL4insc-Mz1407/mspsd03376
chbP4 has larval neuron phenotype, enhanceable by Abl2
chbP4 has larval neuron phenotype, enhanceable by Abl4
chbP4 is an enhancer of larval neuron phenotype of Abl2
chbP4 is an enhancer of larval neuron phenotype of Abl4
chbP4, sli2/sli[+] has larval neuron phenotype
chbP4, sli2 has larval neuron phenotype
Expression of mspsd03376 in the nervous system under the control of Scer\GAL41407 in a chbP4 mutant background generate a severe ectopic midline crossing defect, often affecting numerous segments.
The frequency of axons ectopically crossing the midline in chbP4 Abl4 double homozygous embryos is substantially increased compared to the frequency seen in either single homozygote. The frequency of axons ectopically crossing the midline in chbP4 Abl2 double homozygous embryos is substantially increased compared to the frequency seen in either single homozygote. sli2 chbP4 double heterozygous embryos have axons ectopically crossing the midline. capt10 chbP4 double heterozygous embryos do not show a significant increase in axons ectopically crossing the midline compared to controls.
The effects on viability, mitotic phenotype and mitotic progression suggest an allelic series: chbEP3515 < chbv40 < chbEP3403 < chbP4.