Ptp4E¹ Ptp10D¹ double mutants exhibit bubble-like cysts with an enlarged diameter in unicellular (lateral trunk, ganglionic branch) and intracellular (lateral ganglionic branch) tracheal branches, but not in multicellular branches (dorsal trunk) or intracellular fusion branches. This phenotype is significantly reduced by Scer\GAL4^btl.PS-mediated expression of exp^{B.Scer\UAS.T:Ivir\HA1}.

Unlike in wild type, stage 16 Ptp10D¹ Ptp69D¹/Df(3L)8ex25 double mutant embryos exhibit a Fas2-positive commissural tract with several distinct bundles, oriented perpendicular to the longitudinal tracts. The inner longitudinal bundle is present, but the outer two bundles are missing or fused with the inner bundle. No complete breaks are seen in the Fas2-positive longitudinal tract. The anterior and posterior commissures are fused into a single commissural tract.

Ptp10D¹ enhances the ectopic midline crossing phenotype that is seen in sas¹⁵/Df(3R)ED5221 mutant stage 16 embryos. Multiple Fas2-positive axon bundles cross the midline in each segment, and these are perpendicular to the longitudinal tracts. The inner Fas2-positive bundle is intact, but one or both of the outer longitudinal bundles are missing.

Ptp10D¹ enhances the ectopic midline crossing phenotype seen in homozygous sas¹⁵ mutant stage 16 embryos.

A Ptp10D¹ mutant background enhances the ectopic midline crossing phenotype seen in stage 16 embryos expressing sas^Scer\UAS.cLa under the control of Scer\GAL4^sim.PU. No effect is seen when sas^Scer\UAS.cLa is expressed under the control of Scer\GAL4^elav.PU.

A Ptp10D¹ mutant background enhances the ectopic midline crossing phenotype seen in stage 16 embryos expressing sas^Scer\UAS.cLa in glia under the control of Scer\GAL4^repo.PU. The inner Fas2-positive axon bundle crosses the midline, but the outer bundles usually do not. The pattern of glial nuclei is quite disorganised; the double row of nuclei along each longitudinal tract is replaced by aggregations of varying width, and there is no segmentally repeated pattern of nuclei near the midline.

Ptp10D¹ Ptp4E¹ double mutants die as hatched larvae with collapsed tracheae. The tracheae have large bubble-like cysts on select branches and dorsal tracheal trunk are serpentine (indicating an increased length). The overall branching pattern of the tracheal network is normal.

The junctions between the transverse connective and lateral trunk branches are enlarged in stage 14 Ptp10D¹ Ptp4E¹ double mutant embryos. The anterior branches of the lateral trunk (which have not yet fused across segmental borders) have large cysts and the ganglionic branches have small cysts, By stage 15, cysts are seen at all transverse connective/lateral branch junctions and along the lateral trunk and ganglionic branches in the double mutant embryos. The visceral branch also develops large cysts at this stage.

Ultrastructural analysis of sections through lateral trunk branches shows that the cysts seen in Ptp10D¹ Ptp4E¹ double mutant embryos have variable diameters, averaging around 4.6μm. Cysts and normal lumens are never seen in the same section, suggesting that cysts in unicellular tubes are expanded forms of lumen sealed with adherens junctions.

Cysts are seen in the ganglionic branches and the diameter of the ganglionic branches is larger than normal in Ptp10D¹ Ptp4E^KG02328 double mutant embryos.

Expression of Egfr^{2.A887T.Scer\UAS} under the control of Scer\GAL4^btl.PS enhances the tracheal defects seen in Ptp10D¹ Ptp4E¹ double mutant embryos; the increase in diameter of the transverse connective/lateral trunk junction is further enhanced, and cysts appear on all dorsal branches.

Ptp4E¹, Ptp10D¹/Y double mutant animals can hatch out into first instar larvae, but die immediately after hatching.

Ptp4E¹ Ptp10D¹ double mutants show mild central nervous system defects. The longitudinal axons appear wavy and the outermost longitudinal axon tract is discontinuous and often invades the middle (intermediate) longitudinal axon tract.

Df(1)ovo4 Ptp10D¹ double mutants show mild central nervous system defects. The longitudinal axons appear wavy and the outermost longitudinal axon tract is discontinuous and often invades the middle (intermediate) longitudinal axon tract. A mild fraying of the longitudinal bundles is observed.

Ptp4E¹ Ptp10D¹ double mutant larvae have severe tracheal defects.

In Ptp10D¹; Ptp69D¹/Df(3L)8ex25 double mutant embryos, two longitudinal bundles are observed that sometimes fuse into one, and the ventral nerve cord is narrowed, suggesting that the outer bundle is missing. The mutant nerve cords also display occasional ectopic midline crossing defects by single axons in the posterior commissure. Ptp10D¹; Ptp69D¹/Df(3L)8ex25 double mutants have ISNb branches that fail to reach muscle 12 (stall phenotype), however, these branches maintain a growth-cone like appearance.

Ptp4E¹ Ptp10D¹; Ptp69D¹/Df(3L)8ex25 triple mutant embryos show midline crossing defects in the ventral nerve cord. There are always two, and sometimes three, longitudinal bundles in the triple mutant. The triple mutants have a stronger ISNb phenotype than any of the component double mutants. This is a "clump" phenotype in which 90% of ISNbs terminate in a darkly staining blob at the dorsal border of muscle 6. In cases where the ISNb passes this point, it is often misrouted, or bypasses the muscle field by growing along the ISN. The axons often ectopically project interiorly to muscle 12 from the ISN. In Ptp4E¹ Ptp10D¹; Ptp69D¹/Df(3L)8ex25 triple mutants, the ratio of very thin SNa nerves is increased, compared to Ptp10D¹; Ptp69D¹/Df(3L)8ex25 double mutants.

Ptp4E¹ Ptp10D¹ Ptp52F^18.3 triple mutants have stronger motor axon phenotypes than Ptp52F^18.3 single mutants. The triple mutants also exhibit an enhancement of the ISN truncation phenotype seen at the second branchpoint in Ptp10D¹ Ptp52F^18.3 double mutants.

bif^R47/+; Ptp10D¹/+ double mutants show clumps and breaks in the lamina, while neither single heterozygote shows this phenotype.

In Ptp10D¹ Ptp69D¹ double mutant late stage 16 and early stage 17 embryos longitudinal axons abnormally cross the midline.

Ptp69D^{ΔIg.Scer\UAS} driven by Scer\GAL4^elav-C155 rescues the Ptp10D¹ Ptp69D¹ double mutant ventral nerve cord phenotype.

Ptp69D^{wedge.Scer\UAS} driven by Scer\GAL4^elav-C155 rescues the Ptp10D¹ Ptp69D¹ double mutant ventral nerve cord phenotype.

Ptp69D^{DA1.Scer\UAS.T:Hsap\MYC} driven by Scer\GAL4^elav-C155 rescues the Ptp10D¹ Ptp69D¹ double mutant ventral nerve cord phenotype.

Ptp69D^{ΔPTP2.Scer\UAS} driven by Scer\GAL4^elav-C155 rescues the Ptp10D¹ Ptp69D¹ double mutant ventral nerve cord phenotype.

Ptp69D^{ΔFNIII.Scer\UAS.T:Hsap\MYC} driven by Scer\GAL4^elav-C155 fails to rescue the Ptp10D¹ Ptp69D¹ double mutant ventral nerve cord phenotype.

Ptp69D^{DA1DA2.Scer\UAS.T:Hsap\MYC} driven by Scer\GAL4^elav-C155 fails to rescue the Ptp10D¹ Ptp69D¹ double mutant ventral nerve cord phenotype.

In Ptp10D¹ Lar^5.5/Lar^13.2 Ptp99A¹/Df(3R)Ptp99A^R3 triple mutant embryos the two inner bundles of the ventral nerve cord are very similar to that of wild-type, but the outer bundle, which develops later, is often discontinuous.

Ptp10D¹ Ptp69D¹ Ptp99A¹/Df(3R)Ptp99A^R3 triple mutant embryos produce a phenotype in which the three longitudinal ventral nerve cord bundles are partially fused and many axons cross the midline.

The Ptp10D¹ Lar^5.5/Lar^13.2 Ptp69D¹ triple mutant embryonic phenotype involves ectopic midline crossing and longitudinal bundle fusion by the ventral nerve cord. The axons that abnormally cross the midline in the triple mutant embryos often grow diagonally to the other side without respecting the normal borders of the anterior and posterior commissures. In many cases, all of the connective axons appear to be rerouted across the midline, producing complete connective breaks.

Most of the ventral nerve cord axons abnormally cross the midline and the longitudinal bundles are almost absent in Ptp10D¹ Lar^5.5/Lar^13.2 Ptp69D¹ Ptp99A¹/Df(3R)Ptp99A^R3 quadruple mutant embryos. The longitudinal tracts are depleted of axons and the commissures are completely fused and much thicker than normal. No axons are ever observed to enter the ventrolateral muscle field in the quadruple mutant embryos.

In Ptp10D¹ Ptp69D¹ double mutant embryos, the normal SNa bifurcation is not observed in some hemisegments. The mutant SNa nerves either stall at the bifurcation point or, more commonly, have only one branch (either anterior or posterior) extending beyond this point.

In Ptp10D¹ Lar^5.5/Lar^13.2 double mutant embryos, the normal SNa bifurcation is not observed in some hemisegments. This phenotype is only observed at low frequency.

Approximately half of the SNa nerves fail to bifurcate in Ptp10D¹ Lar^5.5/Lar^13.2 Ptp69D¹ triple mutant embryos.

Approximately half of the SNa nerves fail to bifurcate in Ptp10D¹ Lar^5.5/Lar^13.2 Ptp99A¹/Df(3R)Ptp99A^R3 triple mutant embryos.

Approximately half of the SNa nerves either do not reach the bifurcation point at all or are very thin and wandering in Ptp10D¹ Lar^5.5/Lar^13.2 Ptp69D¹ Ptp99A¹/Df(3R)Ptp99A^R3 quadruple mutant embryos.

Only about 15% of the intersegmental nerves terminate at the first lateral branch point position and most of the remainder stop at the second lateral branch point in Ptp10D¹ Lar^5.5/Lar^13.2 Ptp69D¹ Ptp99A¹/Df(3R)Ptp99A^R3 quadruple mutant embryos.

Approximately half of the intersegmental nerves terminate at the second lateral branch position in Ptp10D¹ Lar^5.5/Lar^13.2 double mutant embryos. The remainder of the intersegmental nerves either terminate between the second lateral branch and the terminal arbor or make an abnormally small terminal arbor in these double mutant embryos.

The longitudinal axon bundles are irregular and often fuse to each other in Ptp10D¹; Ptp69D¹/Ptp69D^8ex25 double mutant embryos.

The outer Fas2-positive bundle is usually missing or reduced to

short, discontinuous Fas2-positive regions, and breaks in the inner

two bundles are also seen. Three or more Fas2-positive axon bundles

that cross the midline are seen within the commissural tracts of each

segment (this is not seen in wild-type embryos). Ptp10D¹; Ptp69D¹/Ptp69D^8ex25

embryos have broader commissures than wild-type embryos, and the intercommissural

space at the midline of the embryo is compressed along the antero-posterior

axis. Reduction in the longitudinal tracts is seen especially in the

intersegmental regions between the neuromeres. Diagonal crossing of

the midline is sometimes seen, with the axon bundle traversing the

intersegmental region between neuromeres where no axons normally grow,

and longitudinal bundles often stop abruptly, causing breaks in the

longitudinal tracts.

The longitudinal pioneer growth cones follow normal pathways in Ptp10D¹

; Ptp69D¹/Ptp69D^8ex25 embryos.

The midline glia appear normal in Ptp10D¹; Ptp69D¹/Ptp69D^8ex25

double mutant embryos. The MP1 and MP2 lineages are indistinguishable

from wild type and the median neuroblast lineage develops normally.

Fas2-positive axons are seen crossing the midline in 95.5% of segments

in Ptp10D¹/Ptp10D¹⁰¹; Ptp69D⁴/Ptp69D^8ex25 double mutant

embryos (this is never seen in wild-type embryos).

No central nervous system abnormalities (by Fas2 staining) are seen

in Ptp10D¹; Lar^5.5/Lar^13.2 double mutant embryos.

Ptp10D¹; Lar^13.2/Lar^5.5; Ptp69D¹ Ptp99A^R3/Ptp69D^8ex25

Ptp99A¹ quadruple mutants have severely disrupted longitudinal

tracts and most axons cross the midline. The bundles that cross the

midline do not respect the normal boundaries of the commissures and

the anterior and posterior commissures appear fused.

Ptp69D^unspecified in double mutant combination with either Ptp10D¹

or Ptp10D¹/Ptp10D¹⁰¹ results in alterations in many central

nervous system axonal pathways in the embryo. The contralaterally

projecting interneuronal axons of the NB 2-5 lineage cross the midline

and turn anteriorly in a normal manner, but then double back across

the midline after about two segments and grow posteriorly in the ipsilateral

longitudinal tract. The axons of the ipsilateral intersegmental neurons

grow anteriorly for a short distance and stop. The ISNd motorneuron

extends an axon toward the midline that stalls and never enters the

ISN root. In the NB 4-2 lineage, the RP2 axons stall before reaching

their target, and the CoR axons do not branch onto all of their target

muscles. The projection of local interneurons across the midline in

the anterior commissure appears wild type, except that the axons always

defasciculate into two bundles after crossing the midline. Ectopic

interneuronal projections form on the ipsilateral side, and project

across segmental boundaries in the anterior direction (these axons

never form in wild type). In the NB 3-1 lineage, the RP neurons (RP1,

RP3, RP4 and RP5) extend axons normally across the commissure and into

the ISNb nerve, although they do not form normal synapses. The interneuronal

projections are radically altered; they still cross the midline, but

do not form defined anterior and posterior projections in the contralateral

connective. Instead, they grow anteriorly in a circular path around

the neuropil, contacting the midline at the end of their trajectory.

No alterations in the numbers or positions of cell bodies of the progeny

of NBs 3-1, 4-2 or 2-5 are seen in these embryos.

Homozygous comm⁵ embryos lack commissural axons. Commissures are

formed in Ptp10D¹; comm⁵ Ptp69D¹/comm⁵ Ptp69D^8ex25

triple mutant embryos (in 37% of segments), and in some cases they

are as thick as in wild-type embryos.

Ptp10D¹; robo¹/robo¹; Ptp69D¹/Ptp69D^8ex25 triple

mutant embryos have a severe phenotype in which most Fas2-positive

axons converge on the midline. Some circles around the midline are

still seen, but many axons fasciculate into a single thick bundle that

extends along the midline. Vestiges of the lateral longitudinal pathways

are seen in some segments.

The Ptp10D¹; Ptp69D¹/Ptp69D^8ex25 double mutant phenotype

is significantly enhanced by one copy of sli²; more Fas2-positive

axons cross the midline, the longitudinal tracts move closer together

and more extensive commissural fusion is seen.

The age-progressive retinal degeneration characteristic for flies expressing Hsap\SNCA^Scer\UAS.cJa under the control of Scer\GAL4^ninaE.PT is significantly enhanced by combination with Ptp10D¹ and Ptp4E¹ in double heterozygous state, combination with single copy of each allele alone does not exacerbate the retinal phenotype.

Ptp69D^{EC.Scer\UAS.T:Mmus\Ptprm} driven by Scer\GAL4^elav-C155 fails to rescue the Ptp10D¹ Ptp69D¹ double mutant ventral nerve cord phenotype.