tutl²³/tutl⁰¹⁰⁸⁵ and tutl⁰¹⁰⁸⁵/Df(2L)tutl larvae show a severe reduction compared to wild-type controls in changing moving direction in response to gentle touch at anterior segments. The number of exploratory head swings in response to the touch, and the time taken to select a new moving direction are increased. The withdrawal response to the gentle touch is normal.

Locomotory behavior in a stimulus-free condition is normal in tutl²³/tutl⁰¹⁰⁸⁵ larvae (number of contractions, average speed, number of turns and average turning angles have been analysed).

tutl²³/tutl⁰¹⁰⁸⁵ larvae show normal phototactic behaviour.

In tutl⁰¹⁰⁸⁵ embryos, the ISNb motor axons succesfully reach the vicinity of their respective targets. However, once there, many fail to send one or more of the final axon branches to contact their muscle targets. Around a quarter of the hemisegments also lack ISNd nerves.

Embryos trans-heterozygous for tutl^ex383 and tutl⁰¹⁰⁸⁵ have defects in commissures, longitudinal connective, and Fas2-positive axon tracts that maintain their relative distance from the midline, but that have axons emanating from all three fascicles bundle together as they cross the midline.

In tutl⁰¹⁰⁸⁵ eye-specific mosaic animals in which over 90% of R7 and R8 cells are homozygous for tutl⁰¹⁰⁸⁵, the R7 and R8 axons are disorganised, despite R7 and R8 terminal layers being evident. Many axonal terminals display abnormal lateral extensions and frequently fuse together, particularly at the R7 terminal layer. tutl⁰¹⁰⁸⁵ mutant R7 and R8 axons from the same ommatidium still associate with each other within the same column.

Single tutl⁰¹⁰⁸⁵ mutant R7 axonal somatic clones display abnormal lateral extension. Compared to wild-type, the frequency of fusion between a labelled tutl⁰¹⁰⁸⁵ mutant R7 axonal terminal and it's neighbors is increased by approximately 4-10 fold. Among them approximately 53% display a 'U-shape' tiling phenotype, in which a mutant R7 terminal branches out from its column at the R7 recipient layer, extend laterally and fuses with its neighboring R7 terminal. In addition, 47% of terminal fusions display a 'V-shape' phenotype in which a mutant R7 terminal appears to move away from its own column and fuses with its neighboring R7 terminal at the R7 recipient layer. Neighboring wild-type R7 terminals also display a similar degree of tiling defects. Many of them display abnormal lateral extension and frequently extend and fuse with their neighboring R7 terminals, indicating a cell non-autonomous tiling role for tutl between R7 terminals. The majority of defective wild-type R7 axons extend towards their neighboring tutl⁰¹⁰⁸⁵ mutant axons.

In the absence of neighboring R7 terminals, the tendency of a tutl⁰¹⁰⁸⁵ mutant axon to invade a neighboring column is decreased from approximately 33% for surrounded R7 terminals to approximately 15% for isolated R7 terminals.

Class I ddaE neurons in tutl⁰¹⁰⁸⁵/tutl²³ larvae have defects in their dendritic trees, including shortened interstitial branches and curled growth lacking directed orientation. There are also significantly more branch termini per neuron compared to wild type. The number of branch points on primary dendrites is unchanged compared to controls, but there is a clear increase in second and third order branch points in the mutant neurons.

tutl⁰¹⁰⁸⁵/Df(2L)ed-dp larvae show defects in the dendritic trees of class I ddaE neurons; there are significantly more branch termini per neuron compared to wild type, and although the number of branch points on primary dendrites is unchanged compared to controls, there is a clear increase in second and third order branch points in the mutant neurons.

Class IV ddaC neurons in tutl⁰¹⁰⁸⁵/tutl²³ larvae show numerous dendrite crossing points, in contrast to control neurons.

tutl⁰¹⁰⁸⁵/tutl²³ larvae show normal dendritic tiling among class IV da neurons (assayed by examining the borders between ddaC and v'ada neurons for dendritic overlap).

Lethal stage is during mid-eclosion. General morphology of the mutant larvae is normal. Mutant larvae respond to tactile stimulation at their anterior end by contracting at both ends and rocking back and forth in place. After a few seconds of this behaviour, the larvae cease this abnormal movement and return to a normal forward-crawling motion. This contrasts with wild-type larvae which respond by showing a characteristic escape behaviour of 1-3 reverse peristaltic movements followed by a lateral turning behaviour. tutl⁰¹⁰⁸⁵/Df(2L)tutl⁴ larvae have a severely compromised ability to roll over from an inverted position; the time required to right themselves is significantly longer than control larvae.

tutl⁰¹⁰⁸⁵/tutl[+] is an enhancer of abnormal neuroanatomy phenotype of Kap-α3^17-76

tutl⁰¹⁰⁸⁵ is an enhancer of abnormal neuroanatomy phenotype of Actβ^RNAi.HL.UAS, Scer\GAL4^GMR.long

tutl⁰¹⁰⁸⁵/tutl[+] is an enhancer of photoreceptor cell R7 phenotype of Kap-α3^17-76

tutl⁰¹⁰⁸⁵ is an enhancer of photoreceptor cell R7 phenotype of Actβ^RNAi.HL.UAS, Scer\GAL4^GMR.long

tutl⁰¹⁰⁸⁵ is an enhancer of eye phenotype of Scer\GAL4^hs.2sev, mbl^C.UAS