14 days old hhhs.PI adult mutants (cultured at 29[o]C to activate expression) display locomotor defects and increased lethality compared to controls and also show lamellar inclusions in brain neurons.
Females in which hhhs.PI is expressed using heat shock twice daily for 3 days followed by a 3 day "chase" show excess follicle stem cell progeny in between egg chambers.
hhhs.PI animals that undergo heatshock during larval stages produce animals with severe head capsule defects.
Overexpression of hhhs.PI (using heat shock) results in an increase in larval eye neurons and optic lobe precursors. Optic lobe and Bolwig's organ tissue is induced in the head midline, resulting in a "cyclops" phenotype (the phenocritical period for this phenotype is between 2.5 and 5 hours).
Heatshock induced expression of hhhs.PI leads to excess follicle cell proliferation and the production of ectopic polar cells. Actin fibres are sometimes, though not always, seen to circle around ectopic polar cells.
Overexpression of hhhs.PI in females results in 87% of germaria having no visible fusome. No spectrosome is visible in early germ cells.
Heat shock treatment of flies carrying one copy of hhhs.PI during the first 5 hours after puparium formation (APF) has no effect on the abdominal cuticle. Heat shocks between 5 and 10 hours APF result in the transformation of posterior tergite microchaetae into macrochaetae. Flies subjected to a single 2-hour heat shock between 11 and 17 hours APF usually appear normal, although weak disturbances in bristle polarity are occasionally seen. Heat shock treatment between 18 and 35 hours APF results in an anterior expansion of the pigment band of the abdominal tergites without any effect on bristle pattern. Flies carrying two copies of hhhs.PI and subjected to three to four 2-hour heat shocks between 5 and 30 hours APF have compressed abdominal tergites which are approximately half their normal width, while the intersegmental membrane is considerably expanded. The polarity of structures in the anterior region of the tergite is sometimes completely reversed, and mirror-image posterior duplications are seen in many abdominal sternites.
Heat induced expression causes expansion of the germarium and excess follicle cells bud off newly formed egg chambers.
Ectopic hh product has little or no effect on smo mutants.
Ectopic activation of hh in the ovaries results in the overproliferation of somatic cells. Excess follicle cells fail to associate with germ-line cysts and accumulate between egg chambers, forming giant 'stalks' which are not formed by true stalk cells.
Heat shock applied for 1 hour twice a day over three days causes a dramatic increase in the number of somatic cells contributing to each ovariole, with excess somatic cells accumulating between the egg chambers. Terminal filament, cap cell and germaria region 1 look normal. Region 2 is swollen and densely packed with cells. Germaria containing hhhs.PI transplanted into non-transgenic hosts show the same effects on ovariole morphology. Chambers that have separated from the germarium are connected by giant stalks containing 25-130+ cells. Ectopic expression of hh affects the positioning of the oocyte within egg chambers and polar cell differentiation, but not the rate of germ line stem cell division.
Overexpression between 3-4 hours of development causes extensive hypertrophy of heart precursor cells.
Failed to induce programmed cell death (PCD) in Df(3L)H99 embryos.
Ectopic expression of hhhs.PI in the anterior compartment of the wing disc results in the duplication of anterior wing structures with mirror image symmetry.
Heterozygotes heat shocked for 5 minutes at 8 hours after egg laying show an increase in rows of 3o cell types at the expense of 4o cell types, with no change to the proportion of the segment made up of 2o cell types. Heterozygotes heat shocked for 20 minutes at 8 hours after egg laying show an increase in rows of 2o cell types at the expense of 3o, and some 4o, cell types. The row of 4o cells closest to the wg expressing cells are unaffected, indicating that they are not competent to respond to increased hh signal. By heat shocking homozygotes, the most extreme degree of transformation is achieved, with increasing levels of hh producing more proximal fates.
After heat shock individuals display abnormal denticle belts. Multiple heat shocks during third larval instar causes wing defects: disorganised wing veins in the anterior compartment and small expansion of the anterior-dorsal wing blade.