tkv8 clones generated from intestinal stem cell clones have significantly more cells than controls clones.
tkv8/tkvk16713 third instar larvae have a significant decrease in total boutons (and satellite boutons) at the neuromuscular junction, compared to wild type. tkv8/+ third instar larvae have similar numbers of boutons to wild type.
tkv8 mutant neuroepithelial cells in optic lobe clones form small ectopic clusters close to the proximal inner proliferation center (p-IPC).
Maternal effect tkv8 embryos (tkv8 mutant mothers crossed with wild-type fathers) appear to develop normally, as the primordial germ cells migrate to and coalesce properly with the somatic germ cell precursors to form an embryonic gonad. The spectrosomes in approximately half of these flies resemble wild-type, with a characteristic spherical shape. The remaining primordial germ cells display spectrosomes that are either bifurcated or have an irregular morphology.
Eight days after induction of intestinal stem cell (ISC) clones, the number of cells in tkv8 mutant clones is significantly higher than in wild-type clones. After injury by feeding bleomycin, mutant clones have more cells than both wild-type clones and mutant clones before injury.
Wild-type clones contain one stem cell, whereas approximately tkv8 mutant clones show a gradual increase in ISC number over time.
One-stem-cell tkv8 mutant clones contain more stem cells than wild-type clones, indicating that mutant ISCs divide more often than wild-type ones.
Clones of tkv8-mutant cells cause premature differentiation of the adult midgut precursor cells into large, polyploid, enterocyte-like cells compared with wild-type cells.
Clones of tkv8 homozygous cells in the pupal retina have defects in the apical profiles and packing of secondary pigment cells relative to tertiary pigment cells. Single, isolated tkv4 homozygous secondary pigment cells in the pupal retina have a restricted apical profile compared to neighbouring wild-type inter-ommatidial cells which expand apically to fill the unoccuppied space.
tkv8 mutant embryos show a delay in dorsal closure and rapture of the dorsal epidermis-peripheral amnioserosa interface, along with discontinuation of F-actin accumulation in the leading edge. The mutants also exhibit rupture of the amino serosa-dorsal epidermis interface.
In tkv8 mutants the F-actin cable is absent in the peripheral amnioserosa, suggesting that specification is incomplete. Time-lapse recording reveals that the progression and removal of the peripheral amnioserosa is delayed.
Somatic clones of tkv8 homozygous cells in the late third instar eye disc are much smaller than wild-type twin spots. However, many of the cells in these clones go on to express neuronal differentiation markers. Mutant cells enter the S phase in the second mitotic wave, but the G2/M transition of this mitosis is disrupted.
When neutral marked clones are induced in the ovary, the proportion of germaria carrying marked somatic stem cells 3 weeks after clone induction is around 70% of that seen one week after clone induction. For tkv8 homozygous clones, the equivalent figure is around 25%. However, the number of resulting clones in the ovarian follicle cells is only slightly reduced compared to controls and these clones have no fewer cells than their twin-spots.
Clones of male tkv8 homozygous germline stem cells are still present in only 1.3X% of testes one week after clone induction and none are present two weeks after clone induction. This is in contrast to wild-type control clones, which are present in 82% of testes one week after clone induction and 64% two weeks after clone induction.
tkv1/tkv8 animals show a significant reduction in neuromuscular junction (NMJ) size compared to wild type; the number of synaptic boutons/muscle surface area at muscle 6/7 is 71.6 +/- 1.9% of wild type. The evoked excitatory junctional potential (EJP) (measured at muscle 6 of segment A3) shows a decrease in amplitude in tkv1/tkv8 animals compared to wild type. Quantal content is reduced compared to wild type.
R8 photoreceptor differentiation is normal in somatic clones of tkv8 mutant cells.
Only 2.5% of ovarioles carry mutant tkv8 germline stem cell (GSC) clones, compared to 11.2% of ovarioles carrying wild-type GSC clones, and many tkv8 GSCs are lost before adulthood.
Homozygous clones in the adult abdomen do not show any effect on polarity.
Mutant embryos have a "dorsal open" cuticle phenotype.
Wing discs are lost completely and the number of proximal leg disc cells is reduced in mutant embryos. The leg phenotype is sometimes variable.
The dorsal branches of the tracheal system do not develop in homozygous embryos, and the more ventral branches are absent or severely affected. Some tracheal cells invaginate in stage 12 embryos but others remain in an intermediate position between the epidermis and the branches that are formed.
Homozygous embryos show a dorsal-open phenotype, with severe head defects and large holes in the dorsal cuticle.
Clonal analysis in the germarium reveals that mutant stem cells are lost more rapidly than wild type, though there is no effect on the formation of 16 cell cysts or their subsequent development. Stem cell half life is 0.69 weeks (wild type being 4.6 weeks). Stem cell division rate relative to control is 0.29.
Tracheal tree defects consisting mainly of a failure to develop some particular branches in the dorsoventral axis. Other tracheal branches form in the anteroposterior axis, though they display an occasional gap.
Embryos exhibit a partial dorsal closure phenotype, leading edge cells are extremely elongated but adjacent more ventral epithelial cells fail to stretch. Most dorsal cuticle is turned inwards and the mouth hooks are retained inside the embryo.
Dorsal branches of the tracheal system are lacking and ganglion branches and the lateral trunk are severely affected.
Mutant embryos show absence of the dorsal branch and lateral trunks. The visceral branch forms normally.
tkv1/tkv8 flies have variable thickening of the wing veins, particularly in regions close to the cross veins and at the distal ends of all longitudinal veins.
Small homozygous clones are observed in the adult eye; photoreceptor differentiation occurs relatively normally, 25% ommatidia are missing one or more photoreceptor cell and the normal precise hexagonal array of the ommatidia is disrupted in the clone and surrounding wild type tissue. Eye is significantly reduced in size or completely missing and the surrounding head cuticle is missing (loss of head cuticle is not caused by put clones).
Dorsal clones induced in second instar larvae in the tarsus convert dorsal cells to ventral or ventrolateral cell fates. Clones often produce outgrowths that include normal neighbours, some of which have been respecified to ventral fates. Ventral clones induced in second instar larvae in the tarsus produce excessive ventral-most structures (peg-like bristles). Tarsal clones cause polarity disruptions in neighbouring normal cells.
Embryos show a dorsal hole. Parts of the dorsal hypoderm in the trunk region are missing. Cephalopharyngeal skeleton is severely disrupted or absent and its remains are forced out of the body cavity. Embryos fail to form the second midgut constriction, and later the gastric caeca are missing. Visceral mesoderm of parasegment 7 is absent. Tracheal system shows a complete absence of dorsally directed trachea, ganglionic branches and lateral trunk. The remaining tracheal lumen is only established in a rudimentary fashion.
Homozygotes display dorsally open cuticle, severe defective head and contracted epidermis giving the cuticle a rounded appearance. Lethal when heterozygous with tkv6. Female transheterozygotes with tkv1 are viable and display a wing phenotype, wing veins are very thick and short along the proximal distal axis, transheterozygotes with Df(2L)tkv3 display extremely thickened wing veins. Adult Df(2L)tkv3/tkv8 females are very weak, possess atrophic ovaries and do not lay eggs in the few days they survive beyond eclosion.
Nondefective in gonad assembly.