The size of smo3
homozygous follicle cell clones in the germarium is significantly smaller than control clones; this phenotype is not associated with an increase in apoptosis (i.e. cDcp1-positive cells) in the germarium, as compared to controls.
homozygous somatic clones in third instar larval eye discs do not enter S transition during the second mitotic wave, except at the edges of the clones.
Homozygous mushroom body gamma neuron clones show normal axon pruning.
Homozygous clones in the eye induced using the ey-FLP/FRT system result in eyes that are smaller than normal with over-represented smo
Somatic clones of homozygous smo3
mutant cells situated close to the anterior side of the anterior-posterior compartment boundary, but not on the posterior side, can be observed to round off. In addition, a tendency of the smo3
mutant clones that immediately straddle the boundary to migrate from anterior towards posterior territory (but not in the opposite direction) is observed.
Cells in homozygous clones straddling the morphogenetic furrow in the eye disc can constrict apically and shorten along their apicobasal axis and can be part of a morphogenetic furrow, although the furrow in the mutant clone is often more posterior in comparison to neighbouring wild-type cells.
Homozygous clones generated using the eyFLP technique result in the occasional loss of one or both third antennal segments or maxillary palps.
In animals containing homozygous smo3
clones induced by eyFLP and with two intact antennae, homozygous Or42a
-expressing olfactory receptor neurons (ORNs) from the maxillary palp correctly target to their normal glomerulus. However, when both antenna fail to form in animals containing homozygous smo3
-expressing maxillary palp ORNs mistarget (7 out of 9 cases), The axons often mistarget to areas normally occupied by antennal ORN axons. Or23a
-expressing ORN axons from the antenna project to their normal glomeruli in animals containing homozygous smo3
clones induced by eyFLP and with no maxillary palp.
somatic clones that span the morphogenetic furrow, nuclei remain apical, rather than moving to the basal side of the cell in the furrow as wild-type cells do.
At least some of the cells in smo3
homozygous somatic clones in the eye disc go on to express markers consistent with normal differentiation of photoreceptors. However, they fail to re-enter the cell cycle at the second mitotic wave. These clones also show evidence of increased cell-death, including dysmorphic nuclei and expression of cell-death markers.
homozygous clones in the dorsal air sac primordium grow normally and populate the tip of the air sac to the same degree as wild-type clones.
The reduction in distance between wing veins III and IV and partial fusions of these veins proximal to the anterior crossvein that is seen in flies expressing smo5A.Scer\UAS.T:Zzzz\FLAG
under the control of Scer\GAL4C-765
are strongly enhanced by smo3
G1 arrest is often delayed by 1-2 cell diameters in smo3
eye disc cells.
S phases and mitoses of the second mitotic wave are delayed but not absent in smo3
mutant cells. However, if the cells immediately posterior are wild type, then smo3
mutant cells enter S phase at the normal time.
Unlike neutral somatic clones, smo3
homozygous somatic clones are rapidly lost from the somatic stem cell population of the germarium.
somatic clones in the scutellum differentiate microchaetes, indicative of transformation into scutum.
R8 photoreceptor differentiation is delayed in smo3
mutant somatic clones.
Somatic clones of smo3
in the ocellar triangle (ocellar cuticle) lead to reduced or absent ocelli. The medial ocellus is occasionally split in two.
Homozygous clones in the wing induced using Scer\FLP1hs.PS
can result in the disruption or partial duplication of wing vein L4, and it may be shifted posteriorly. In addition, double-row wing margin bristles occasionally appear more posteriorly along the wing margin than normal. More severe phenotypes show an increasing anteriorisation of the wing. Homozygous clones in the wing induced using Scer\FLP1Scer\UAS.cCa
expressed under the control of Scer\GAL4dpp.blk1
result in ectopic veins appearing between veins L3 and L4, but no displacement of L4 or defects of the bristle pattern are seen. Homozygous clones induced by using Scer\FLP1Scer\UAS.cCa
expressed under the control of Scer\GAL4dpp.blk1
result in defects in the thorax, head and legs that weaken the flies considerably. Homozygous clones induced by using Scer\FLP1Scer\UAS.cCa
expressed under the control of Scer\GAL4vg.int2.1
result in a wide variety of adult wing defects, but despite the disruption in wing patter, these flies are fully viable and do not show defects in other tissues.
Ommatidial rotation is normal in smo3
mutant clones (n = 53).
Homozygous mutant clones of glial cells do not migrate prematurely at second instar and are found exclusively posterior to the morphogenetic furrow.
Large homozygous clones in the anterior tergite that abut the segment boundary and span the a1, a2 and a3 regions have completely normal polarity both within the clone and in surrounding wild-type cells. The a1 region shows transformation of the cuticle to a2 cuticle. Small homozygous clones in the anterior tergite entirely within the a1 region, and separated from the a2 region by a strip of untransformed a1 cuticle occasionally (2/13 cases) show altered polarity in 1 or 2 cells along the posterior edge of the clone.
Mosaic flies with eyes homozygous for smo3
(clones generated using the "eyFLP" system) have small eyes.
When somatic clones of smo3
are made in the developing eye, there is no significant reduction in the percentage of homozygous mutant cells, and the relative spatial distribution of the glia in the eye disc remains unaffected.
Photoreceptor development is blocked in the central regions of marginal homozygous clones in the eye. This effect is nonautonomous; photoreceptors develop along the outer edges of marginal clones and eventually, throughout internal clones in the eye.
Homozygotes embryos exhibit a lawn of denticles covering most of the ventral surface.
When analysed in clones in the developing eye the number of R8 cell precursors is reduced and their spacing is irregular. The timing of emergence of the mutant R8 cells is normal. Neuronal cells in clones autonomously suffer delay in differentiation. Packing in the ommatidial clusters is disrupted.
somatic clones (24-48hr after egg-laying (AEL)) in the female analia delete part of the dorsal anal plate but do not affect the ventral plate. Clones in the abdominal tergite 8 induce overgrowth. Clones in the perianal ring produce duplicated anal structures. The long bristle of the vaginal plates can also be duplicated. Small clones outside the A/P compartment border had no effect. Clones in male adult terminalia autonomously duplicate the structures close to the Antero-posterior border such as the genital arc, the claspers, and the hypandrium bristle. Large clones in the male analia delete most of the anal plate.
Cells in homozygous clones in the eye disc are capable of differentiating as photoreceptors. However, there is a significant delay - there is a clear posterior displacement in the onset of photoreceptor differentiation in mutant cells; differentiation is first seen at the posterior, and occasionally lateral, edges of the clone.
Denticle belts are made up of mostly type 5 denticles.
Clones induced in the embryo in the posterior domain of the A compartment make a3 cuticle. The most posterior clones move back, behind the twin clone. The mutant clone assumes a smooth elliptical shape. In the a3 territory the boundaries of the clone are wiggly.
clones induced before 72 hours development frequently produce regions of non-cuticular material, thought to be hindgut, in areas that are normally cuticular.
Homozygous clones that include the posterior margin of the lamina furrow lack S phase lamina neuron precursors (LPCs). The scattered S phase cells anterior to the lamina furrow, ad the distribution of S phase cells in other proliferation centres, such as the outer proliferation centre, are unaffected in homozygous clones.
Shows a weak dominant enhancing effect on B
Homozygous phenotype at 25oC is highly variable, ranging from almost wild type to the occasional partial fusion of denticle belts. At 18oC the denticle belts are completely eliminated and the ventral surface of the cuticle is covered in a continuous lawn of denticles of similar size and random polarity.
Clones of cells mutant for smo
redirect the A/P affinity boundary in the developing wing disc. They form a straight boundary when juxtaposed with sister smo+
A cells, but a wiggly boundary with neighboring smo-
cells in the P compartment. Similar results are seen in the adult wing. smo-
cells autonomously form anterior wing margin structures if they are derived from A cells, even when they are located in the domain normally occupied by P-compartment cells.
Clones in the anterior compartment of the adult abdomen develop normally when they arise in the middle of the anterior compartment. Clones that arise near or at the anterior/posterior compartment boundary are transformed, forming cuticle characteristic of a more anterior position within the anterior compartment. This transformation is autonomous. Hairs both within and surrounding the clone often have abnormal polarity, although mutant cells which lie very close to the boundary have hairs with normal polarity. Clones that arise in the a1 anterior region of the anterior compartment are transformed to make a2 cuticle.
Clones in the developing eye retard the progression of the morphogenetic furrow. Photoreceptor differentiation is retarded, but not prevented, concomitantly with furrow progression. Clones in the eye that lack both Pka-C1
behave like loss of function Pka-C1
clones. Clones show ectopic photoreceptor differentiation and eventually merge with the endogenous field of differentiation, show no retardation of the furrow, pass through a furrow fate and induce non-autonomous ectopic photoreceptor differentiation outside the clone.
Mutant embryos show a cold sensitive segment polarity phenotype. At 25oC segmental defects are mild whereas at 18oC embryos variably show a classic segment polarity cuticle phenotype.
Homozygous clones in the developing wing that arise distant from the A/P boundary develop normally. Clones that arise immediately anterior to the A/P boundary are associated with reorganised wing patterns to form a mirror symmetric double-anterior winglet and conversely the posterior compartment is severely reduced.