In mbt^P1/mbt^P1 eye discs of wandering third instar larvae ommatidia lose their cohesion posterior to row 10, while in more anterior row 5 ommatidia display significantly shortened CadN- and shg-immunopositive adherens junctions between photoreceptor precursor cells R3 and R4 and between R2 and R5, respectively.

mbt^P1/mbt^P1 somatic clones of photoreceptor precursor cells R3 and/or R4 (but nor R2, R5 and/or R8) in row 5 display a shortened CadN-immunopositive adherens junction phenotype between R3 and R4. While short adherens junctions occur more often in mbt^P1-null R3 cells, clones affecting R4 show ommatidial rotation defects.

Expressing mbt^UAS.cMa, mbt^K397M.UAS or mbt^H19,22L.UAS under the control of Scer\GAL4^hs.2sev in an mbt^P1/mbt^P1 background leads to the formation of a significant proportion of elongated CadN-immunopositive adherens junctions between photoreceptor precursor cells R3 and R4 in row 5 ommatidia of wandering third instar larvae.

In mbt^P1 hemizygous males have rough eye: the ommatidia contain a variable number of photoreceptor cells, which have misshaped rhabdomeres.

Mutant eyes show defects in the adult eye. A reduced number of rhabdomeres are seen. Those that remain show morphological defects. They are larger than normal, and unlike in the wild-type, neighbouring rhabdomeres often contact each other. Rhabdomeres are also twisted, fragmented and do not extend from the pseudocone to the floor of the retina. In mutant eye imaginal discs some irregularities are seen at the adherens junctions (AJs). In third instar discs the AJs of the developing photoreceptor cells appear disorganised. Frequently the AJs extend laterally. Defects become much more pronounced at pupal stages. At 37% of pupal development (p.d.) AJs fail to extend in the proximal-distal direction. At 50% p.d. AJs are fragments and form patchy and disorganised structures. Occasionally ommatidia contain fewer differentiating photoreceptor cells than wild-type.

Prominent reduction in the mushroom body neuropile size in the hemizygous or homozygous state: Kenyon cell number is reduced. The number of mushroom body neuroblasts is sometimes reduced or a complete failure of some neuroblasts to proliferate. Flies also exhibit a rough eye phenotype, a variable number of photoreceptor cells are missing, and bristle malformations.

mbt^P1 has abnormal neuroanatomy | wandering third instar larval stage phenotype, suppressible | partially by Src42A^26-1/Src42A[+]

mbt^P1 has abnormal neuroanatomy | wandering third instar larval stage phenotype, suppressible | partially by Src42A^k10108/Src42A[+]

mbt^P1 has abnormal neuroanatomy | wandering third instar larval stage phenotype, suppressible | partially by Src64B[+]/Src64B^ko

mbt^P1 has abnormal neuroanatomy | wandering third instar larval stage phenotype, suppressible | partially by Src64B^KG00213/Src64B[+]

mbt^P1 has abnormal cell adhesion | wandering third instar larval stage phenotype, suppressible | partially by Src42A^26-1/Src42A[+]

mbt^P1 has abnormal cell adhesion | wandering third instar larval stage phenotype, suppressible | partially by Src42A^k10108/Src42A[+]

mbt^P1 has abnormal cell adhesion | wandering third instar larval stage phenotype, suppressible | partially by Src64B[+]/Src64B^ko

mbt^P1 has abnormal cell adhesion | wandering third instar larval stage phenotype, suppressible | partially by Src64B^KG00213/Src64B[+]

mbt^P1 has abnormal size | wandering third instar larval stage phenotype, suppressible | partially by Src42A^26-1/Src42A[+]

mbt^P1 has abnormal size | wandering third instar larval stage phenotype, suppressible | partially by Src42A^k10108/Src42A[+]

mbt^P1 has abnormal size | wandering third instar larval stage phenotype, suppressible | partially by Src64B[+]/Src64B^ko

mbt^P1 has abnormal size | wandering third instar larval stage phenotype, suppressible | partially by Src64B^KG00213/Src64B[+]

mbt^P1 has adherens junction | wandering third instar larval stage phenotype, suppressible | partially by Src42A^26-1/Src42A[+]

mbt^P1 has adherens junction | wandering third instar larval stage phenotype, suppressible | partially by Src42A^k10108/Src42A[+]

mbt^P1 has adherens junction | wandering third instar larval stage phenotype, suppressible | partially by Src64B[+]/Src64B^ko

mbt^P1 has adherens junction | wandering third instar larval stage phenotype, suppressible | partially by Src64B^KG00213/Src64B[+]

mbt^P1 has photoreceptor R3 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src42A^26-1/Src42A[+]

mbt^P1 has photoreceptor R3 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src42A^k10108/Src42A[+]

mbt^P1 has photoreceptor R3 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src64B[+]/Src64B^ko

mbt^P1 has photoreceptor R3 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src64B^KG00213/Src64B[+]

mbt^P1 has photoreceptor R4 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src42A^26-1/Src42A[+]

mbt^P1 has photoreceptor R4 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src42A^k10108/Src42A[+]

mbt^P1 has photoreceptor R4 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src64B[+]/Src64B^ko

mbt^P1 has photoreceptor R4 precursor cell | wandering third instar larval stage phenotype, suppressible | partially by Src64B^KG00213/Src64B[+]

mbt^P1 has eye phenotype, suppressible | partially by tsr[+]/tsr^N96A